Wastewater Treatment and Management in Northern Canada - 2016 edition

January 2016 Edition

Iqaluit

Grise Fiord Technical Publications of Ken Johnson, MASc, RPP, PEng and and Co-authors ken.johnson@cryofront.com

Ulukhaktok

Fort Smith

Whitehorse

Wastewater Treatment and Management in Northern Canada Kugaaruk

Wastewater Treatment and Management in Northern Canada Technical Publications by Ken Johnson, M.A.Sc., RPP, P.Eng., and Co-authors 2nd Edition, January 2016 Table of Contents 1. Fifty Years of Wastewater Management and Improvements In Iqaluit. Published In Western Canada Water Magazine, Spring 2015. ....................................................... 1 2. The Challenges With Mechanical Wastewater Systems In The Far North. Published in The Proceedings of the Annual Conference Of Western Canada Water and Waste Association, 2014. ............................................................................................................ 3 3. Successful Lagoon Operation In Northern Communities. Published In Environmental Science and Engineering Magazine, October 2014. .................... 13 4. A Comparison of Water And Sanitation In The Canadian North And The American North. Published In The Proceedings of The Annual Conference of Western Canada Water and Waste Association, 2013. ......................................................... 15 5. CCC in The Close Quarters of a Northern Water and Sewer Access Vault. Published in Western Canada Water Magazine, Spring 2013. ................................................ 25 6. The Extreme Cost of Northern “Liquid Assets.” Published In Western Canada Water Magazine, Fall 2013. .................................................................................................... 27 7. City of Dawson Wastewater Treatment – Biosolids Management. Published in Western Canada Water Magazine, Fall 2013. .......................................................... 29 8. Innovation Gone Wrong – The Sh#%T Hits The Trailer Park In Yellowknife. Published in Western Canada Water Magazine, Winter 2012. .................................................. 31 9. Project Delivery In The Far North – Then And Now. Published In Western Canada Water Magazine, Winter 2011. ..................................................................................... 33 10. Wastewater Sampling Challenges In Grise Fiord and Other Northern Communities.

Published in the Journal of the Northern Territories Water and Waste Association, 2010. ............................................................................................................................... 37 11. Fort Resolution Wastewater Management Study. Published in the Proceedings of the Annual Conference of Western Canada Water and Waste Association, 2010. ........................................................................................................................................... 41 12. Giant Mine Water Management System. Published in the Journal of the Northern Territories Water and Waste Association, 2010. ........................................................ 51

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13. Utilidor Replacement in Inuvik. Published in the Proceedings of the Annual Conference Of Western Canada Water And Waste Association, 2010. ............. 55 14. Sewage Composting in Iqaluit Nunavut – Black Gold. Published in the Proceedings of the Annual Conference of Western Canada Water and Waste Association, 2009. ................................................................................................................................ 63 15. Dawson City Digs Deep For Sewage Treatment. Published in Western Canada Water Magazine, Winter, 2009. ................................................................................... 75 16. Diavik Diamond Mine Water Management Plan. Published in the Journal of the Northern Territories Water and Waste Association, 2009 .......................................... 77 17. Water and Sewer Challenges in Kashechewan, Ontario. Published in the Journal of the Northern Territories Water and Waste Association, 2009. ................................ 83 18. Infrastructure Serving Dawson City, Yukon – The New Klondike Gold. Published in the Proceedings of The Annual Conference Of Western Canada Water and Waste Association, 2009. .......................................................................................................... 89 19. Advancing Wastewater Treatment In Inuit Regions of Canada. Published in the Proceedings of the Annual Conference of Western Canada Water and Waste Association, 2008. .......................................................................................................... 97 20. A Brief History of The Past 60 Years of Northern Water and Waste. Published in the Proceedings of the Annual Conference of Western Canada Water and Waste Association, 2008. ........................................................................................................ 109 21. Cambridge Bay, Nunavut, Wetland Planning Study. Published in the Journal of The Northern Territories Water and Waste Association, 2008. ..................................... 117 22. Aerated Lagoon in the Canadian North – Fort Nelson Bc Facility. Published in the Journal of the Northern Territories Water and Waste Association, 2007. . .......... 121 23. The Social Context Of Wastewater Management in Remote Communities, Published in the Proceedings of the Annual Conference Of The Western Canada Water and Waste Association, 2007. ........................................................................ 127 24. Engineered Improvements to Sewage Treatment System In Cambridge Bay, Nunavut. Published in the Proceedings of the Annual Conference of the Canadian Society For Civil Engineering, 2007. ........................................................................... 137 25. Wetland System for Treatment of Landfill Runoff In Iqaluit, Nunavut. Published in the Proceedings of the Annual Conference of the Canadian Society for Civil Engineering, 2007. ....................................................................................................... 145 26. Water and Sewer Systems Serving Dawson City Yukon. Published in the Journal of the Northern Territories Water and Waste Association, 2007. ................................ 153

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27. Application of Large Scale At-Grade Sewage Treatment and Disposal in Fort Good Hope, Nt. Published in the Proceedings of the Annual Conference of the Canadian Society for Civil Engineering, 2006 .......................................................... 157 28. Integrated Waste Management in Iqaluit, Nunavut. Prepared for Consulting Engineers of Alberta Award Application, September, 2006. Received Award of Merit, Municipal Engineering Category. ................................................................. 165 29. Design and Winter Construction Of Sewage Lagoon Discharge Pipeline in Landslide Area Near Fort Smithy, Nwt. Published in the Proceedings of the Annual Conference of the Canadian Society for Civil Engineering, 2006. ..................... 173 30. Livingston Trail Environmental Control Facility, Whitehorse, Yukon. Published in the Journal of the Northern Territories Water and Waste Association, 2005. ............ 181 31. Performance and Potential Improvements to Anaerobic Sewage Lagoon in Fort Mcpherson, Nt. Published in the Proceedings of the 12th International Cold Regions Engineering Specialty Conference, 2004.. .............................................................. 187 32. The Future of Wastewater in a Global Water Shortage. Published in Environmental Science And Engineering. May, 2004. .................................................................... 201 33. Land Use Planning and Waste Management in Iqaluit, Nunavut. Published in Proceeding of the Annual Conference of the Canadian Institute of Planners. July, 2001. .............................................................................................................................. 203 34. Technologies For Use in On-Site Wastewater Recycling Within Cold and Remote Regions. Cryofront Journal of Cold Region Technologies. Published in 2000. ..... 207 35. Sewage Treatment Systems In Communities and Camps of the Northwest Territories, and Nunavut Territory. Published in the Proceedings of the 1st Cold Regions Specialty Conference of the Canadian Society for Civil Engineering, 1999. ......................................................................................................................................... 217 36. Evaluation of the Impact of Secondary Sewage Discharge on the Aquatic Environment of Kodiak Lake Near Ekati Diamond Mine, Nt. Published in the Proceedings of the 1st Cold Regions Specialty Conference of the Canadian Society for Civil Engineering, 1999. ........................................................................... 227 37. Design and Construction of Sewage Lagoon in Grise Fiord, Nunavut. Published in the Proceedings of the 7th International Conference on Permafrost, 1998. ..... 237 38. Preliminary EngineeringoOf Sewage Disposal System in the Community of Repulse Bay, Nunavut. Published In The Proceedings of the Annual Conference of the Canadian Society for Civil Engineering, 1994. ....................................................... 245

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39. Performance Evaluation of Primary Sewage Lagoon In Iqaluit, Nunavut. Published in the Proceedings of the 7th International Cold Regions Engineering Specialty Conference, 1994. ....................................................................................................... 255 40. Alternative Concepts for Water and Sewer Main Access in the Northwest Territories.

Published in the Proceedings of the Annual Conference of the Canadian Society for Civil Engineering, 1990. . ....................................................................................... 265 For more information about cold region technology contact: Ken Johnson, M.A.Sc., RPP, P.Eng. Senior Environmental Engineer and Planner Stantec kenneth.johnson@stantec.com.com T : 780 984 9085 www.issuu/cryofront www.youtube/cryofront

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TREATMENT PLANT UPGRADING

50 years of wastewater management and improvements in Iqaluit GLENN PROSKO, AND KEN JOHNSON, STANTEC CONSULTING, EDMONTON

In 1964, a water treatment plant was constructed beside Lake Geraldine above the community of Frobisher Bay. This facility set the stage for ‘modern’ water and sanitation facilities in the community – and what has become an infrastructure quandary for the community of Frobisher Bay, now the City of Iqaluit.

Directly to the ocean At the discharge end of the water system in 1964, the sanitary sewer outfall consisted of a five-pipe system that discharged raw sewage directly from a gravity collection system into the salt water of Koojesse Inlet. The community has led the way in many circumstances with innovation and leadership in advancing ‘standards and criteria’ for water and sanitation systems in the far north. At the same time, the community has been at the mercy of a variety of circumstances that have placed the community many steps behind in elements of the infrastructure expectations for what was a regional centre, and is now a capital city.

The shoreline discharge of raw sewage was maintained for the next dozen years until the construction of several lift stations provided the means to pump the sewage to a macerator system at the head of Koojesse Inlet. The macerator technology was constructed at six sites across the Northwest Territories

(NWT and Nunavut), and ultimately the technology failed at all of the locations.

The formal explanation for the failure was “vortexing problems with the bagged sewage in the hopper,” and the informal explanation was that the honey bags (plastic bags containing the sewage) were too strong and ultimately jammed the macerator.

The macerator experiment was probably the first experience that the communities of the north with ‘inappropriate’ large-scale water and sanitation technology.

Successful lagoon operation Concurrent with the construction of the macerator station in Iqaluit was the construction of a holding pond built on the tidal plain at the head of Koojesse Inlet. The lagoon was created by the construction of two berms, which connected the existing shoreline to an island.

This facility operated successfully for several decades, although several overflow and breaching events demanded improvements in the earth structures, and the perimeter drainage to the facility. The lagoon performed well as a primary treatment facility, with a continuous discharge, providing 10 to 15 days of detention time. The effluent quality from the lagoon systems varied significantly over the course of the year because the only process at work in the

The wastewater treatment facility in Iqaluit is situated at the head of Koojesse Inlet, beside a primary sewage lagoon that was used for many years.

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winter months was sedimentation, with biodegradation enhancing the process performance during the summer months.

Great expectations Expectations for improvements in the primary treatment system prompted Iqaluit in the early ‘90s to retain a consultant to complete an engineering feasibility study for improving the wastewater treatment system. The initial scope of work included only the consideration of improving the sewage detention capabilities, with the expectation that this would improve upon the overall quality of the primary effluent.

This scope of work was expanded to include options for a mechanical treatment system; these options included a rotating biological contactor (RBC), an extended aeration system (EA) and a sequencing batch reactor (SBR). These options were evaluated against nine lagoon options that included relocating the lagoon facility to other areas on the perimeter of the community. The highest rated scenario from a decision analysis evaluation was the construction of a new facility, consisting of a detention lagoon (primary treatment) west of the community, and the construction of an outfall into the deeper water of Koojesse Inlet; the capital cost of this option was estimated to be $5.7 million (1994 dollars). None of these options advanced beyond the feasibility stage.

Construction in 2005 provided preliminary and primary treatment to an MBR facility that was abandoned by a design build contractor.

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A design-build experience Regulatory pressure was placed upon Iqaluit to advance a system capable of producing secondary treatment effluent quality. Based upon a 1997 decision, a design-build request for proposals was issued, and a proponent was selected to build a secondary sewage treatment facility. A design-build contract was awarded in 1998, and the contractor selected a membrane bioreactor (MBR) process applying the Zeeweed membrane technology.

The inexperience of the design builder in northern wastewater treatment became evident by mid-1999.

Significant problems began to arise concerning the placement of concrete within the water retaining aeration basins. Upon filling the basins, major leakage was observed, in addition to deflections in the walls of the basins due to insufficient structural strength.

To effectively deal with the problem, Iqaluit suspended all construction activities, and retained the services of a third-party structural engineer to complete the necessary structural investigations and make recommendations for remedial work.

Remedial work was completed, and the water retaining aeration basins were determined to be structurally sound and waterproof.

At this point, the design builder effectively abandoned the project.

Iqaluit subsequently became aware of additional design and construction problems with the facility.

Evaluation of an un-commissioned facility An evaluation of the un-commissioned sewage treatment plant was completed in 2002, and included an accounting

Septage (trucked) sewage is currently dumped into the sewer system immediately upstream of the wastewater treatment facility.

of all the electrical, instrumentation, mechanical, structural, and architectural equipment or features found within the plant; and comparing this to the equipment and features presented in the design documents. This accounting identified significant deficiencies in both the design and construction.

These deficiencies were generally associated with the hydraulic capacity, process efficiency, overall durability against extreme cold weather conditions, and a corrosive plant environment.

As well, the deficiencies were associated with the ability of plant personnel to operate and maintain a complex and highly automated facility in a safe, efficient, and practical manner.

The evaluation presented recommendations to replace, or modify, electrical, instrumentation, mechanical, and structural elements of the existing facility. In consultation with Iqaluit, a remedial work plan was developed to utilize a conventional wastewater treatment process technology, and abandon the application of MBR technology.

Moving forward with secondary treatment The move forward with remedial work was presented in a phased approach recognizing that the financial capacity of Iqaluit may dictate an incremental approach. As well, a phased approach recognized the efficiency of expanding the facility with the population increase in the community.

The design of the remedial work incorporated the existing structure and process equipment as much as possible, which was a hallmark feature of the work. Phase 1 of the design

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proceeded to construction to complete a primary treatment system for a design population of 12,000. The treatment processes consisted of an auger screen from the original facility, and a primary screen (Salsnes Filter) housed in an addition to the original building envelope. This addition also provided a building envelope for the sewage lift station associated with the original work.

Phase 2 would include the design and construction of a secondary clarifier to match the hydraulic capacity of the aeration basins to be converted from the MBR process. The completion of new secondary clarifiers would provide for a fully functional secondary treatment plant capable of handling the flow for a population of 8,000.

A future Phase 3 for the facility would include the design and construction of additional aeration basins with the hydraulic capacity for a population of 12,000. However, the available funding for the project accommodated only the completion of Phase 1, and Phase 2 was shelved for implementation in the future.

Eight years after completion of the Phase 1 work, the project is proceeding and the City of Iqaluit has retained Stantec to provide wastewater and cold regions engineering expertise for the completion of the feasibility phase of a secondary sewage treatment facility. An important consideration for the facility is the influence of septage (trucked sewage) on the facility performance, which still accounts for about one-third of the flow into the facility. The feasibility stage of the project will make sure that “no stone is left unturned” regarding treatment alternatives, as the community embarks on the final chapter in a process that has been ‘in the works’ for 20 years.

Spring 2015

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TREATMENT PLANT UPGRADING

The wastewater treatment facility currently provides primary treatment, which discharges at the head of Koojesse Inlet. Work is proceeding to complete a secondary sewage treatment improvement to the facility.

Western Canada Water Conference and Exhibition September 23-26, 2014 Regina Saskatchewan

The Challenges with Mechanical Wastewater Systems in the Far North Ken Johnson, Stantec, Edmonton, AB Glenn Prosko, Stantec, Edmonton, AB David Lycon, Stantec. Surrey, BC ABSTRACT The consistent performance of wastewater treatment in the far north of Canada, in general, remains an elusive objective, and a frustration for engineers, communities, senior governments and regulators. Lagoon systems suffer from performance inconsistencies, and a significant scientific effort has been underway by the Government of Nunavut to study and predict the performance of lagoon systems. It has been pointed out that those systems which are technologically simple, and engineered for sufficient capacity tend to perform well, however lagoon systems are ultimately at the mercy of the natural environment, which is extreme in the far north. Mechanical systems do offer the opportunity to reduce the influence of the natural environment, however a multitude of other factors affect the design, construction, operation and maintenance of mechanical systems in the far north. As an opportunity to mitigate the challenges associated with mechanical wastewater systems, a synopsis of the community mechanical treatment facilities in the north has been compiled. Lessons learned from the challenges with mechanical wastewater systems in the far north have been catalogued as a legacy document to future project stakeholders. This compilation is a first attempt to provide a documentation to serve as a reference for improving the development, execution, and operation of future mechanical wastewater treatment projects, where this technical option is deemed appropriate.

INTRODUCTION Wastewater management practices in the Yukon, Northwest Territories and Nunavut Territory have undergone tremendous change over the past 40 years. These changes have been the most profound in the small communities, where the term “honey bucket” remains well known. The transition from the “honey bucket” to pressured water systems has meant that the management of community sewage has changed, in principle, from a

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solid waste to a liquid waste, which is now generated in relatively large volumes. To cope with these large volumes of liquid waste, most northern communities now use pond systems to detain or retain the volume prior to discharge. These pond systems are either natural systems or manmade systems.

Along with the technological transition has come a regulatory change with the development of regulatory requirements for the discharge of effluent from the sewage ponds. Before the creation of Nunavut, the Northwest Territories Water Board had the sole responsibility for dictating the discharge criteria from sewage ponds; the general criteria applied for effluent discharges were 180 mg/ L for BOD5, and 120 mg/L for total suspended solids (TSS). A detention lagoon with a continuous discharge providing around 10 days of hydraulic retention will generally meet this criteria, with the exception of BOD5, which may not be achieved in the winter because of the cold temperatures that adversely impact biological activity.

Most northern communities utilize either sewage detention (ponds with continuous discharge) or sewage retention (ponds with periodic discharge), and overall these systems perform well because of the simple technology. Exceptions to the application of sewage detention or retention have emerged due to site specific conditions that generally exclude their application because of topographic conditions, where terrain is too rough for the construction of a lagoon, or land use issues, where proximity to other development restricts the siting of a lagoon.

A significant intervening factor for wastewater management in the far north has been the Wastewater Systems Effluent Regulations, which have been developed under the Fisheries Act, to fulfill a commitment under the Canadian Council of Ministers of the Environment (CCME) Strategy for the establishment of national effluent quality standards.

The essence of the “harmonized� wastewater effluent criteria has been to standardize effluence quality targets of 25 mg /L for cBOD and 25 mg/L for TSS. Unfortunately these criteria are generally not appropriate for wastewater lagoon systems in the north, due to the harsh climate, and the seemingly perpetual winter. While only the Yukon has formally adopted these standards, the other territories and the northern regions of Quebec (Nunavik) and Labrador (Nunatsiaput) are attempting to work within the "spirit" of the regulations.

The consistent performance of wastewater treatment in the far north of Canada, in general, remains an elusive objective and a frustration for engineers, communities, senior governments and regulators.

PERFORMANCE OF LAGOON SYSTEMS Detention lagoons provide a continuous discharge, and retention ponds provide a periodic, usually seasonal, discharge. Overall these systems tend to perform well because of the simple technology, although there have been problems with undersized systems, maintenance deficiencies, poor construction, and poor operation practices.

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The performance data on lagoon systems (retention lagoon) in the north is limited, but indicates a BOD5 reduction in the range of 90 to 95 percent (BOD5 less than 150 mg/L and as low as 11 mg/L), TSS reduction in the range of 90 to 95 percent (TSS less that 80 mg/L and as low as 5 mg/L) and fecal coliform reduction in the range of 2 to 4 logs (fecal coliforms less than 2x106 and as low as 3x101). The influent sewage is estimated to be 600 mg/L BOD, 725 mg/L SS, and 107 coliforms/100 mL. The capital cost of lagoon systems in the north are highly variable depending upon the location, the availability of suitable construction materials, competitiveness, and contractor experience and confidence. The construction of any lagoon system in the far north is a multi- million dollar capital project.

The operation and maintenance of a lagoon system and the association sewage collection system is also highly variable. In Grise Fiord, the annual cost for water and sewer was approximately $2240 per capita; the sewage portion of this cost was approximately $670 per capita.

From an operational perspective, any sewage treatment system, particularly mechanical sewage treatment systems, have significant cultural and language barriers, which must be addressed on a daily basis. For example, the biological aspects of sewage treatment process are difficult to explain in Nunavut because the Inuktitut language has never historically had the need for words like clarifier or biomass.

NUNAVUT MECHANICAL TREATMENT SYSTEMS Only three communities in Nunavut, namely Rankin Inlet, Pangnirtung, and Iqaluit, use mechanical sewage systems. The system in Rankin Inlet is preliminary treatment to remove large solids by screening. The system in Pangnirtung is secondary treatment, which originally used a rotating biological contactor. The system in Iqaluit has preliminary and primary treatment for the removal of solids by screening. Although designs for secondary treatment systems have been completed in Rankin Inlet, and Iqaluit, construction of the advanced systems has not yet been authorized. All of these mechanical systems have significant operating challenges.

Rankin Inlet The sewage treatment system serving Rankin Inlet is a rotating drum screening plant.

Prior to 1996 and the construction of this system, Rankin was discharging into Johnston Cove immediately in front of the community. The discharge into the Cove had limited dispersion, therefore odour and sewage accumulation on the shoreline was a big problem.

The screening facility was originally constructed with a 0.3 millimetre screen size, however due to clogging of the screen associated with oil and grease, the screen size was changed to a 1 millimetre screen size.

Raw sewage enters the plant, and accumulates in a surge tank, before being pumped through the rotating screens. The treated sewage is discharged by gravity into Prairie

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Bay by way of a deep water outfall. A number of modifications were completed to the original installation due to site specific issues. The most significant issue was the sewage backup due to the tidal activity, which caused the discharge to back up into the plant during a high tide. This issue was solved with the installation of an air release valve on the outfall pipe.

Another issue was the accumulation of oil and grease on the rotating screen. This was partially addressed with the increase in the screen size, but ultimately a screen cleaning system using a surfactant, in combination with a hot water spray solved the problem.

Rankin Inlet has a completed design for a secondary sewage treatment system that is awaiting funding before proceeding.

Pangnirtung Pangnirtung utilizes a secondary sewage treatment process for the community’s wastewater. The facility was originally constructed as an RBC (rotating biological contactor system), but numerous problems with the process equipment prompted the community to adapt the system to a conventional activated sludge process.

Raw sewage enters the facility from a truck dump, and passes through a pre-screen that is maintained with raking by hand. This step removes towels, plastics, condoms, and other garbage, which are bagged and disposed of at the municipal landfill. From the pretreatment, the sewage enters a 190,000 litre aerator drum, which oxygenates the flow in advance of the bioreactors. In the bioreactors aerobic decomposition occurs, and the odor associated with this part of the process has been noted to be negligible. From the bioreactors the wastewater flows to a clarifier, which provides quiescent flow conditions to allow the biomass settle, and the clear effluent flows over the discharge weirs to the effluent outfall.

Biosolids from the various process segments are fed into a 90,000 litre anaerobic digester to stabilize the biomass. The biosolids from the digester are dewatered, mixed with a polymer and bagged in 23 kilogram containers for disposal at the municipal dump.

Iqaluit Iqaluit issued a design/build request for proposal (RFP) for secondary treatment in 1997 to replace the existing primary lagoon system. The terms of reference in the RFP were vague, but an underqualified British Columbia (B.C.) based company responded and captured the project. The main contract was not executed for a considerable time after the work had begun, therefore the work proceeded using rudimentary service contracts.

The contractor took advantage of this situation to maintain a comfortable cash flow without the technical substantiation normally demanded, since Iqaluit did not have an independent owner’s representative until well into the project. Unfortunately, Iqaluit expended the entire contract amount of $7 million without the substantiation that would later reveal that the facility did not meet code on many items, and the concrete aeration

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basins were grossly under designed (basin walls displaced upon filling with water), and poorly constructed (basins leaked significantly).

A consultant was retained in 2004 to complete the design for an extensive rehabilitation of the facility. The design was able to incorporate the existing facility, but required two additions to the building; one addition for primary treatment (completed in 2006) and another addition for clarifiers (still to be completed). The estimated capital cost for the additional work is $18 million ($3 million for primary treatment and another $15 million for the yet to be completed secondary treatment).

Iqaluit wastewater treatment facility in July, 2013.

NWT AND YUKON MECHANICAL TREATMENT SYSTEMS Only three communities in the Northwest Territories and the Yukon, namely Fort Simpson, NWT, Carmacks, Yukon and Dawson City, Yukon use mechanical sewage treatment systems. All of these facilities are secondary treatment systems with a disinfection process.

Fort Simpson, Northwest Territories Fort Simpson has been under the regulatory pressure since the 1980’s to construct a secondary treatment facility, in spite of the fact that the dilution rate in the Mackenzie River (sewage to river flow) is over 300,000 to 1 at the lowest possible river flow. Fort Simpson advanced a project for improvements in the early 1990’s with a building, and a treatment process using drum screens with the intent of adding a rotating biological contractor (RBC) process in the future.

Fort Simpson advanced a design/build proposal in 1997 to move to secondary treatment, and Proteus was the selected process with the low capital cost being the determining factor in the selection process. The Proteus system abandoned the drum screens in

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favour of a physical / chemical process. The system was commissioned in 2002, but it has experienced constant performance issues, and as a result, Fort Simpson has been to court several times with the contractor.

Fort Simpson has been able to maintain the operation of the Proteus system for almost a decade through their own ingenuity, however the regulatory demands for process improvements finally prompted the community to advance remedial work. The capital cost of the current remedial work on the WWTP is $3.7 million, which will retrofit the facility with a sequencing batch reactor (SBR) system fitting into an existing building.

Dawson City, Yukon Dawson City was charged under the Fisheries Act in 2002 for discharge of a deleterious substance, and a court order for the construction of wastewater treatment improvements followed. Dawson had been planning to construct an SBR facility, and a design was ready for tendering in 2002, but the annual operation and maintenance estimate of $600 thousand halted the project because it was thought to be too expensive.

A new project emerged with the objective of constructing an aerated lagoon just south of the community, and the project advanced to preliminary engineering in 2008.

Unfortunately, this project stopped dead in its tracks on a land use referendum because of the lagoon’s proximity to a residential subdivision. The Yukon Government then decided to advance a design/build proposal for a mechanical system, and a design/build contract for $25 million was awarded to a contractor in 2009 applying the Vertreat process (deep shaft technology).

The Vertreat process is a high rate aerobic process which utilizes two, one meter in diameter and 100 metre deep shafts as the aeration basins. The injection of air under high pressure (100 metres) increases the oxygen saturation to 4 times the normal levels and as the activated sludge is saturated with air, it floats in the clarifier. Startup of the facility occurred in August 2012, but the facility, as of mid-2014, has still not consistently met the performance criteria in the contract.

The estimated annual operation and maintenance costs for this facility may exceed $800 thousand.

Dawson City wastewater treatment facility during construction in February, 2012.

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Carmacks, Yukon The original Carmacks WWTP was commissioned in 1975, and the facility operated successfully for 35 years. In the 1990’s the facility was definitely showing its age, and some “hay wiring” was ongoing to keep it running. A planning study was completed in 2004 to look at various process technologies, particularly a lagoon system, but the topography around Carmacks is steep, so a significant pumping system would be required to convey the sewage to a lagoon site.

A design/build request for proposal was issued in 2005 for a mechanical system, but this process went sideways when the Yukon Government did not approve of the proponent “selected” by the community, which represented the GE Zeeweed membrane technology.

The Yukon Government was able to cancel the project for the GE system, and advanced a solution on a piecemeal basis to replace the existing system.

The project was advanced in several stages with the process procurement of an extended aeration activated sludge system as the first stage, followed by the procurement of the building system and the associated equipment. In the end, the overall cost of the facility exceeded the $6 million proposal submitted for a design/build project.

The facility has operated reasonably well since it was commissioned in 2009. A detailed inspection of the facility was completed in 2012, and recommended a number of improvements.

FACTORS INFLUENCING MECHANICAL SYSTEMS IN THE NORTH Natural Environment The natural environment will always have a great influence on the built environment which is associated with any mechanical WWTP in the north. The natural environment influences community access for construction, and operation and maintenance with weather extremes, and highly variable weather at times. This factor prevails whether a community has an all weather road, or if the year round access is limited to aircraft and relying on the annual sealift for the majority of the community resupply. Since the beginning of modern development over a century ago, the north has been a challenging environment for access, and this has not changed for the most part. A community such as Dawson City still remains a challenge for easy access a 115 years after the Klondike Gold Rush.

The climate segment of the natural environment in northern communities is extremely cold, with an average daily mean temperature of less than zero degrees centigrade for most of the far north. This propensity for cold means that all built infrastructure must be designed and constructed for protection against freezing, and in some cases be designed and constructed with provisions for thawing if the facility freezes.

The geography segment of the natural environment in northern communities generally creates great distances between the individual communities themselves, and between the

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communities and major centres further south. In the Yukon, most of the communities have all weather roads so access is simplified, however the road distances are great. In the NWT many communities have all weather road access, and the remainder of the communities have year round access by air, and seasonal access by winter road, or sealift.

In Nunavut, none of the communities have all weather road access, and rely solely on year round access by air, and resupply during the sealift period between late July and mid-October.

Design and Construction The design and construction of a mechanical WWTP in the far north should follow the well established procedures and practices, however these procedures and practices are frequently misunderstood or poorly managed, and the end result are facilities that do not perform. The selection of a WWTP process for the north should be carefully executed because the north is not an appropriate testing realm for new technologies or technologies that do not have a ”track record” of performance. An example of this is the selection of a membrane bioreactor in 1997 for the Town of Iqaluit, which was a process technology that was relatively new in southern Canada, and poorly applied to a northern situation.

The consulting resources applied to a WWTP in the north should have the appropriate northern experience and expertise in all of the technical disciplines associated with a WWTP, which includes wastewater process, structural, geotechnical, heating and ventilation, electrical, and instrumentation and controls. This experience and expertise must be demonstrated as part of the selection process during the request for proposals.

An example of the poor selection was the structure engineer's experience associated with the concrete aeration basins for the Iqaluit WWTP; the actual experience of the engineer was associated with concrete residential building foundations in the Okanagan region of British Columbia, and not water retaining structures in a northern environment. This same structural engineer also certified the electrical design drawings for the project.

The contractor experience applied to a WWTP should have the appropriate northern experience. Without this experience, the contractor will ultimately encounter problems at some point in the project. For example, the design build contractors for the Fort Simpson, Dawson City, and Iqaluit WWTP's had never before completed a project of a similar of size, and scope in the far north, and as a result, all of these projects encountered major problems in the project execution.

The attention to developing a comprehensive contract associated with the construction of a mechanical WWTP in the far north is an “up front” effort that pays off later on. A poor level of detail was apparent in the request for proposals on the Iqaluit design/build WWTP, which resulted in potentially fewer contractor responses, and greater uncertainty in the project deliverables.

Once a comprehensive contract is prepared, the execution of the contract itself must by completed with the same level of effort and attention to detail as the original contract. In spite of the most comprehensive contract prepared in advance of a project, the poor

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execution of the contract itself may significantly influence the outcome of a project. For example, the executed contract for Dawson City omitted the design drawings by mistake, which allowed the design build contractor additional unwarranted flexibility in the execution of the project. Another example is the Town of Iqaluit, which executed the initial part of the work without a signed contract, using simple service contracts to advance the administration for payment. This ultimately resulted in a WWTP project that expended $7 million, and was never commissioned in its original design.

The contract administration must have the resources in place to provide comprehensive contract monitoring, reporting, and responses from beginning to end of a WWTP project in the north. Without this dedicated resource, a project will deviate from the project objectives and may not recover. For example, the Town of Iqaluit did not retain an owner’s representative for the 1997 WWTP project until well over a year after the construction began, and ultimately this facility was never commissioned in its original design.

The transportation of materials to a site anywhere in the far north is a logistical challenge in each and every aspect of the process. These challenges include transportation scheduling, and maintaining the material integrity during transportation; the material may literally "fall off the wagon" during the transportation to the site. For example, the process tankage for the Carmacks WWTP fell off the truck during transportation to the Yukon, jeopardizing the commissioning of the project.

The opportunity for the preparation of construction materials on the site in a northern community may offer the potential opportunity for applying features that will improve the performance of the facility, or reduce the cost of construction. However, materials prepared on site, such as structural concrete, are a potential source of problems; for example, poor concrete used in the construction of the water retaining structures on the Dawson City WWTP has jeopardized the design life of the project.

Operation and Maintenance Operation and maintenance success of facilities in the far north has been suggested to be the ultimate indication of a project’s success. Operation and maintenance creates a legacy for community, which may last a generation (25 years), equating to the anticipated design life of a mechanical WWTP. The operation and maintenance itself, along with the operation and maintenance documentation and the operation and maintenance training, are distinct aspects of the overall operation and maintenance of a WWTP. Operation and maintenance considerations of a facility should begin at the same time as the process design, involving resources with operation and maintenance experience; these considerations should be revisited throughout the design process. If not, a facility may have chronic operational problems from the time of commissioning; for example the Dawson City facility process is still not successfully operational 2 years after “startup” of the facility in August 2012.

11

The documentation associated with the operation and maintenance should be a well defined part of the contract with significant monetary milestones for delivery. Without a monetary or some other incentive, satisfactory documentation may never be delivered on a project. An example of this is the Dawson City operation and maintenance documentation, which remains incomplete 2 years after facility startup.

The training and staffing associated with a mechanical WWTP are aspects of a project that may generally not "enter the picture" until the project is near completion. The challenges of training and staffing are compounded in the north as a result of general human resource issues, and therefore this aspect of a WWTP project should be started at the same time as the design, and be continually advanced throughout the project. Ideally at the time of the project commissioning, the training and staffing should be complete.

CONCLUSIONS In spite of the challenges that mechanical WWTP systems in the north, there are a few successes. The most significant success story has been the mechanical WWTP in the community of Pangnirtung, Nunavut, where the interest and efforts of the local operator have maintained the successful operation of the facility.

Mechanical WWTP’s have experienced many challenges in their application in the far north, however, they do offer the opportunity to reduce the influence of the natural environment. In considering a mechanical WWTP, the multitude of factors associated with the design, construction, operation and maintenance of these systems in the far north must be fully considered. The experienced technical disciplines must also be fully engaged for the duration of the project.

The consideration of operation and maintenance of a WWTP, and the engagement of the local human resources to be responsible for the operation and maintenance, cannot be over emphasized. A WWTP is a community legacy that will last a generation, and significantly impact the human and financial resources of the community.

The synopsis of systems presented in this paper from across the far north is complete in the facilities it has presented (6 in total), but is not complete in the presentation on each facility. This documentation will provide information to hopefully to mitigate many of the challenges associated with mechanical wastewater systems for future facilities.

However, each and every project in the north is unique, so ultimately there is no "recipe" for success, however with the communication of project experiences, the potential list of things that can go wrong when a project is underway may be greatly reduced.

12

13

14

Western Canada Water Conference and Exhibition September 17-20, 2013 Edmonton Alberta

A COMPARISON OF WATER AND SANITATION IN THE CANADIAN NORTH AND THE AMERICAN NORTH Ken Johnson, Stantec ABSTRACT The challenges associated with water and sanitation in the Canadian north (Yukon Territory, Northwest Territories and Nunavut Territory), and the American north (Alaska) are much the same with the extremes in climate, geography and socio-economics.

However, the water and sanitation approaches applied in each region have evolved with different technical approaches, administrative support, political, and socio-economic influences.

The current status of water and sanitation in the smaller communities of Alaska (excluding the North Slope) is that approximately 55 percent of the communities have piped systems (135 communities); 21 percent have onsite household systems (50 communities); 18 percent are unserved (45 communities) and 4 percent have hauled systems (10 communities). The unserved communities in Alaska have access to "washeterias", which are centralized water and sanitation facilities. In comparison with the Canadian north, only 18 percent of the communities are piped (16 of 85 communities) and the remaining 84 percent have trucked (hauled) water and sanitation.

This difference in service levels is a function of capital funding, but also the historical philosophy toward water and sanitation in each of the regions. The capital funding difference is that multiple funding agencies may provide independent dollars in grant funding. The philosophical difference is that no operation and maintenance funding has been provided for water and sanitation in Alaska, whereas considerable operation and maintenance funding is provided in northern Canada.

The anticipated outcomes of these different approaches to water and sanitation are the cause of considerable concern in both regions. In Alaska, the investment in capital projects has an associated concern for the necessary follow-through operation and maintenance. There are also public health concerns with the "user pay" approach in Alaska, which influences the household water and sanitation practices. In the Canadian north, the increasing high capital costs water and sanitation projects, and the unfolding

15

regulatory framework, particularly for sanitation, has created concerns for the costs, and the operation and maintenance legacies.

HISTORY AND CURRENT STATUS OF WATER AND SANITATION IN THE NORTH The history of water and sanitation in northern Canada may be followed back to the turn of the last century in the community of Dawson City, Yukon. The development of the industrial mining activity near Dawson, following the Klondike gold rush, included a large scale hydraulic project called the “Yukon Ditch” which conveyed water 110 kilometre for hydraulic mining. With this industrial scale of water conveyance, a modest water and sewer system was developed within the townsite of Dawson City. This system provided a continuous supply of water that was freeze protected by continuous bleeding to the river, and construction adjacent to steam lines. However, Dawson's system was unique, and other modest systems did not follow until the 1940's when Yellowknife and Aklavik installed seasonal surface distribution systems.

The construction of the Town of Inuvik in the late 1950's was the first modern water and sewer system in the Canadian north. Other piped systems were constructed in the 1960’s and 1970’s with the expansion of the community infrastructure in the communities of Whitehorse, Norman Wells, Fort Simpson, Fort Smith, Rankin Inlet, and Iqaluit.

However the majority of the water and sanitation infrastructure in the Canadian north has remained trucked water supply and trucked sewage collection. Of the 84 communities in the Yukon, Northwest Territories and Nunavut, only 16 of the communities (18 percent) have piped systems, and the remaining 84 percent have trucked (hauled) water and sanitation.

This history of water and sanitation in Alaska had a similar start with water systems constructed by the industrial activity associated with the Alaska Railroad. The original water system for Anchorage was constructed by the Alaska Railroad in 1917, and in 1921 the City of Anchorage purchased the water system and associated water rights. Fairbanks water and sewer system also grew from the industrial activity associated with the Alaska railway in the 1920’s. The capital city of Juneau developed its water and sanitation systems after it was declared the capital city of Alaska in 1906, although significant development did not occur until the late 1920’s.

The remainder of the Alaskan communities, numbering close to 250 remained essentially unserviced until the 1950’s. In 1950, fewer than 10 percent of Rural Alaska homes had modern sanitation. In 1954, when the U.S. Public Health Service created the Indian health program with a mandate to improve native Alaskan health; at the time infectious diseases were responsible for 46 percent of the deaths of Alaska Natives. Between 1950 and 1970 the improvements to the water and sanitation in the rural communities were modest, whereas the improvements to water and sanitation in the larger communities of Anchorage, Fairbanks and Juneau were significant.

In the 1970’s a concerted effort was made to provide centralized water and sanitation facilities to communities, with the objectives of 100 percent water treatment to full

16

regulatory compliance, storage of large quantities of water, distribution of treated water to individual homes through pipes or haul vehicle, and collection of household sewage for lagoon disposal. The achievement of this water and sanitation servicing object has been slow given the number of communities and the capital costs. Alaska today has a population of 730,000 people, of which 300,000 live in Anchorage and 30,000 each live in Fairbanks in Juneau. All of the remaining communities have populations of less than 10000 people. Approximately 70,000 of the estimated 120,000 Native Alaskans live in 170 rural villages with populations of less than 300 people each.

The current status of water and sanitation in the smaller communities of Alaska (excluding the North Slope) is that approximately 55 percent of the communities have piped systems (135 communities); 21 percent have onsite household systems (50 communities); 18 percent are unserved (45 communities) and 4 percent have hauled systems (10 communities).

CURRENT TYPES OF WATER AND SANITATION SYSTEMS IN THE NORTH In Alaska, the existing systems are comprised of washeterias and central water points, individual well and inground systems, water and sewer truck or trailer haul systems, and piped water and sewer systems.

Washeterias and central watering points are treated drinking water sources delivered to a single service connection and people must use their own containers to collect drinking water. This service level (referred to as "unserved") does not provide drinking water or wastewater removal from homes, which means that the basic health benefits of running water and flush toilets are not realized. Individual wells and septic systems make use of the favourable in-situ soil conditions, which includes the absence of significant permafrost. The concerns with this service level, is that the systems often do not meet the minimum separation distances for safety, for example wells can become contaminated with inadequately treated sewage if the proximity is too close.

Figure 1: “Washeteria� Facility in Buckland, Alaska Trailer haul systems, which are a scaled down version of a truck haul system, utilize 4 wheel all terrain vehicles (summer) and snowmobiles (winter) to pull specially designed

17

trailer mounted water or sewage containers. These systems have high operating costs, which are passed on to the residents without any subsidy. An outcome of this user pay approach is that the homeowners often self-limit water use and reuse the dirty water multiple times which leads to the spread of disease.

Figure 2: Flush Tank and Haul System in Alaska Piped water and sewer systems is the service level which provides centralized water and sewage treatment with the piped distribution of water and piped collection of sewage.

In Canada, the service levels are grouped into trucked services (water supply and sewage pickup) and piped services (pipe water distribution and piped sewage collection). A common denominator between the trucked and piped systems is the need for water and sewage treatment systems. The technologies for water treatment are ultimately site specific, but the water treatment processes generally strive for a multi-barrier treatment systems with disinfection upon discharge into the distribution system. The preferred sewage treatment system is a lagoon retention system with seasonal discharge, although there are variations on this system, and 6 communities in the Canadian north have mechanical sewage treatment systems.

Figure 3: Trucked Sewage Collection in Canada (Pangnirtung) This overall difference in types of water and sanitation systems in northern Canada and Alaska is a function of the design philosophy and site specific design criteria, and capital

18

funding, but also the historical philosophy toward water and sanitation in each of the regions. The capital funding difference is that multiple funding agencies may provide independent dollars in grant funding. The philosophical difference is that no operation and maintenance funding has been provided for water and sanitation in Alaska, whereas considerable operation and maintenance funding is provided in northern Canada.

THE TURNING POINTS FOR NORTHERN WATER AND SANITATION The relationship between water use and incidence of disease (more water use and less incidence of disease) has been a theory for more than 50 years, but with little or no scientific evidence of the relationship. In the Canadian north, research into this relationship was completed in the mid 1980’s, which ultimately provided a mathematical relationship shown in Figure 3, which suggests a decrease in the incidence of intestinal disease with water use levelling out at 90 litres per capita per day. This research was adopted into a water and sanitation policy that is applied in the Northwest Territories and Nunavut. Prior to this research, the policy for water supply in the Northwest Territories / Nunavut was 45 litres per capita per day.

Figure 4: Relationship between the Incidence of Intestinal Disease and Water Use in Northern Canada In Alaska, the absence of in-home access to safe drinking water and sewage disposal is a documented cause of high disease rates, including severe skin infections and respiratory illnesses. Several recent Alaskan studies found that a lack of in-home piped water service is associated with higher incidence of respiratory tract and skin infections among rural Alaska Natives. However, the Alaskan studies, unlike the Canadian studies in the 1980’s, did not relate disease rates to per capita water use, and their general conclusion is that there is no “magic number” for per capita water use and incidence of disease.

Consequently, Alaska does not have any particular policy on minimum water supply quantities.

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In Alaska, conventional, community-wide piped systems and truck haul systems are increasingly expensive to construct, maintain and replace. The available capital funding cannot meet the demand for new systems and rehabilitation of aging systems. As well, many communities cannot afford the high operation and maintenance costs associated with piped or haul systems. These emerging realities have prompted Alaska to embark on a significant program to develop and implement decentralized water and sanitation systems.

DIFFERENCES IN NORTHERN CANADIAN AND ALASKAN DESIGN CONSIDERATIONS The design considerations for northern Canada and Alaska are a function of the climate, geography, geology and populations, and design objectives of the various regions. The vast geography of the regions results in substantial differences in climate and geology, which manifests itself in the seasonal temperature extremes, the nature of the permafrost, and the nature of in-situ soils. These criteria directly influence the design considerations for water and sanitation in the north. Table 1 presents a specific comparison of design considerations that are applied in the Canadian north and Alaska.

Table 1: Differences in Design Considerations Component Source water preference

Canadian North Surface water

Alaska Ground water

Distribution system preference

Truck haul distribution

Piped distribution

Facility selection analysis

Low life cycle cost

Low operational cost

Community size

Larger average community size

Smaller average community size

More specific differences in the design considerations in the Canadian north and Alaska may be identified in a comparison of the completed infrastructure in Inuvik, Northwest Territories, and St. Michael, Alaska. In comparing the completed utilidor in Figure 5 (Inuvik), and the utilidor in Figure 6 (St. Michael), the Canadian system is more robust with independent water and sewer piping support by a steel pile system. The robust nature of the Canadian is reflected in the cost of $6,000 to $8000 per metre.

20

Figure 5: Canadian “Utilidor” System in Inuvik, Northwest Territories

Figure 6: American “Utilidor” System in St Michael, Alaska

DIFFERENCES IN CANADIAN AND ALASKAN POLICIES The policies concerning water and sanitation systems in northern Canada and Alaska provide another significant difference in the water and sanitation service level that is delivered to communities as presented in Table 2. The Canadian government policy of national health care provides an overriding objective for government assistance to water and sanitation, which translates into operation and maintenance subsidies, and specific policies for water quantity in addition to water quality.

21

Table 2: Differences in Administration of Water and Sanitation Services Component Operation and maintenance subsidies

Canadian North Operation and maintenance subsidies

Alaska No operation and maintenance subsidies

Government obligation

Provide healthy living conditions

Provide sanitation infrastructure

Health care system

National health care system

No national health care system

Water quality and quantity

Policy to provide quantity and quality to protect human health

Policy to provide quality to protect human health

DIFFERENCES IN CANADIAN AND ALASKAN FINANCIAL CONSIDERATIONS The financial considerations concerning water and sanitation systems in northern Canada and Alaska provide another significant difference in the water and sanitation service level that is delivered to communities as presented in Table 3.

Table 3: Differences in Financial Considerations Component Capital costs

Canadian North Invest in lower capital costs for trucked infrastructure

Alaska Invest in higher capital costs for piped infrastructure

Operation and maintenance costs

Range to be $200,000 to $400,000 for a community

Anticipated to be $100,000 for a community

Administration of service

Service not discontinued for non-payment

Service discontinued for non- payment

Dispersion of financial assistance

Only Territorial governments provide financial assistance

Difference entities provide independent financial assistance

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THE “PIPE” AHEAD FOR NORTHERN WATER AND SANITATION IN NORTH AMERICA In northern Canada there are three significant areas of concern and, in addition to the continuing overall concern about the capital, and operation and maintenance costs. 

Water treatment processes to respond to regulatory demands – the Guidelines for Canadian Drinking Water Quality have been adopted as law in the Yukon and the Northwest Territories, and may be eventually adopted by Nunavut, and with this legislation comes the demand for more sophisticated water treatment technologies.



Certification of water treatment operating staff to respond to regulatory demands – the Guidelines for Canadian Drinking Water Quality have been adopted as law in the Yukon and the Northwest Territories, and may be eventually adopted by Nunavut, and with this legislation comes the demand for operator certification to respond to regulatory demands



Wastewater treatment processes to respond to regulatory demands – the Canadian Council of Ministers of the Environment have developed a harmonized wastewater effluent quality guideline that has been adopted by the Yukon Territory, and could be adopted by the Northwest Territories and Nunavut, and with this legislation comes the demand for hundreds of millions of dollars in capital expenditures, and tens of millions of dollars in operation and maintenance expenditures.

In Alaska, cost is the overriding area of concern associated with water and sanitation.

More specifically the concern is associated with the large gap in capital needs and available capital funding, as well as the operation and maintenance costs for water and sanitation infrastructure. This concern is being addressed in principle by a program to develop and implement decentralized water and sanitation systems. The program recognizes that a decentralized approach provides small scale treatment at each home, and the potential for reduced capital and operation and maintenance costs. Alaska has stated the position that innovative technologies hold the most promise for use in delivering affordable water and wastewater services to rural Alaska.

REFERENCES Ritter, T.L. Sharing Environmental Health Practice in the North American Arctic: A Focus on Water and Wastewater Service. April, 2006.

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24

THEME:

CROSS

CONNECTION

CONTROL

CRYOFRONT: News, Views and Muse from the Far North

CCC in the close quarters of a northern water and sewer access vault

By Ken Johnson, Stantec

manholes were problematic from the start because this technology was not suited to the demanding environment of the active layer with the ground movement and the seasonal groundwater flow. Problems that commonly occurred included water infiltration into the vaults; physical and moisture damage to the internal urethane insulation; difficulty of access to appurtenances; and freeze breakage of piping and appurtenances.

The innovation to solve this problem in the 1980s was the introduction of the Access Vault as a replacement for manholes. The access vault provides access to both the sewer and water system, which are essential for maintenance activities of cleaning and the unique nothern requirement of draining and thawing. The proximity of the water and sewer provides a heat source from the sewer, but the sewer also creates the potential for cross connection. The cross connection potential demanded a robust mechanical design, which is a mechanical marvel. Another part of the use of these systems was the definition for regulatory purposes. Manholes were for sewage only, whereas access vaults, by definition could contain water and sewer lines. To ensure no cross connection can occur, the sewer lines are completely sealed within the vault and are only accessible through a normally bolted access

Inside access vault with hydrant (vertical section of pipe)

hatch, which is sealed with a flexible gasket.

Installation efficiency was also substantially improved with access vaults, and commissioning was less challenging as the vaults had been tested prior to shipment from the factory.

Studies have been undertaken to investigate alternate, less costly concepts to the insulated steel water and sewer acccess vaults used, however the robust design needed for the harsh arctic environment has not been matched. These design features include: access for sewer clean out; access for thawing sewer main; access for draining water main; access for thawing water main; access to operate, maintain and repair appurtenances; freeze protection for hydrants incorporated into vaults; resistance to all uplift forces; resistance to thaw settlement; and prevention of all ingress of water; and accommodation of thrust forces due to expansion and contraction of pipe.

The insulated steel access vault that is presently used has rectified all of these problems associated with the previous designs. However, these vaults may cost in excess of $100,000, which includes supply and installation of all fittings and appurtenances. The cost of the access vaults may represent 30% of the contract price for the piped utilities system, but the performance of the vaults over the past several decades has justified their expense.

Photos courtesy of Steve Burden, exp

C

ross connections may not have the same importance in the North by the fact that most of the communities do not have piped services. If my math is correct, of the 85 or so communities in the northern territories (Yukon, NWT and Nunavut), only 16 or 20% have piped systems. The remainder have trucked systems, which pose unique problems unto themselves.

Back in the 1960s, water and sewer mains were constructed using asbestos cement piping. The above ground portions were installed in sheet metal boxes, which were filled with vermiculite insulation. The innovation introduced during this iteration of servicing was the concept of recirculation and reheating. Heat was added at specific points in the system and recirculation was provided by parallel small diameter copper pipes.

The next great evolutionary step was the introduction of buried servicing. This innovation brought a host of benefits, most significantly the placement of the pipe in the constant temperature of the ground rather than the extreme cold of the winter air. Buried installation was possible due to improved materials such as piping that was pre-insulated with polyurethane foam.

Along with buried pipe came heated concrete manholes for system access. Concrete

Several access vaults awaiting installation

25 30 | Western Canada Water | Spring 2013

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26

Cryofront: News, Views and Muse from the Far North

The extreme costs of Northern “Liquid Assets”

By Ken Johnson, Stantec The extreme cost of northern water, for both capital cost and the operation and maintenance costs, is a reality that northern water practitioners are very familiar with and manage, as best they can, as part of their work in the north. However, periodic reality checks on these extreme costs even surprise the most experienced northern water practitioner. Such is the case with the recent tenders received for piped water and sewer replacement in Resolute, Nunavut (See Figure).

Resolute is the second most northerly community in Canada, situated on Cornwallis Island at 74°42’N and 94°50’ W. The community has a population of approximately 250, and is served by a shallow buried piped water and sewer system that was constructed in the mid 1970s. The climate in Resolute is particularly challenging, with the average annual temperature being a chilly -16.7°C, and the lowest recorded temperature being - 52.2°C. The permanent community of Resolute was established in 1953

76 | Western Canada Water | Fall 2013

as part of an effort to assert Canadian sovereignty in the high arctic during the Cold War, because of the area’s strategic geopolitical position. This led the Government of Canada to forcibly relocate Inuit from northern Quebec to Resolute, and also to Grise Fiord. Expectations of establishing a significant northern presence in the 1970s prompted the Government of Canada to establish a new Resolute townsite adjacent to the existing townsite with shallow buried piped water and sewer system. The expectation at the time was that Resolute would grow to a population of several thousand people; this growth never occurred, and Resolute has maintained a population of only several hundred people.

The water and sewer system has encountered operating challenges associated with freezing of the piping, and significant operating costs associated with high rates of water bleeding to prevent freezing. The steady deterioration of the system prompted the Government of the

27

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Northwest Territories (prior to the formation of Nunavut) to plan for replacing the system in the mid 1990s. The question of replacement of the existing piped system versus transition to a trucked delivery system has been studied numerous times since then. Currently, most of the communities in Nunavut are on a trucked water system, except for larger hubs of Iqaluit and Rankin Inlet.

The most recent study was not conclusive on the whether trucked services would in fact be cheaper than piped services due to the anticipated costs of retrofitting the buildings for trucked services. As well, there is a strong sentiment within the community that the piped delivery of water and sewer services should be maintained.

As presented in the News from the Field, the piped utility replacement project was put on indefinite hold after the lowest tender received for the project was $44.4 million. The lowest bid put the construction portion of the project approximately $18 million (70%) over the pretender construction estimate of $26 million.

As jaw dropping as capital costs can be in the far north, the operation and maintenance costs are, in some cases, even more astounding, as can be seen in the following tables for the remote communities of Whati, in the Northwest Territories, and Grise Fiord in the Nunavut Territory (See Figure). Grise Fiord is the northern most community in Canada.

Table 1. Whati, NWT Operation and Maintenance costs Year

Water $

Sewer $

Total $

2001

167,800

71,900

239,700

2002

184,600

79,100

263,700

In comparison to the cost of water in these communities, the cost of water is a mere 0.12 cents per litre in Edmonton. A quick mathematical comparison places water costs in Whati 13 times more expensive than Edmonton, and water costs in Grise Fiord a whopping 38 times more expensive than Edmonton.

The term “liquid asset” for water and sewer infrastructure takes on a whole new meaning in the far north, and will continue to provide financial challenges to both the capital, and operation and maintenance costs. Added to the financial challenges are the technical challenges of designing, constructing, operating and maintaining northern water and sewer infrastructure.

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Table 2. Grise Fiord, Nunavut Operation and Maintenance costs Year

Water $

Sewer $

Total $

2001

234,391

100,200

334,591

2002

255,959

109,696

365,655

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28

Fall 2013 | Western Canada Water | 77

Theme:

Biosolids

cryofront City of Dawson wastewater treatment – biosolids management Ken Johnson, NTWWA Director Once commissioned in 2012, the Dawson City, Yukon, wastewater treatment plant will produce primary washed screenings and biosolids. Both the screening, and biosolids will be periodically hauled to the municipal landfill referred to as the ‘Quigley Landfill,’ which is nine kilometres east of the town, for disposal.

In the summer, volumes may require one trip to the landfill every two-to-three days using a truck or trailer system. In the winter, little to no sludge will be removed from the plant.

Remediation and neutralization of the biosolids will take place in excavated trenches over a number of years, and ultimately the material may be used as cover material. The proposed management system combines the process technologies of air drying, freezing/thawing, anaerobic digestion and long retention times.

The biosolids disposal configuration at the landfill is the narrow trench method, and the biosolids will be disposed in the trench year

Trench excavation for Dawson City biosolids management system.

round. Water loss by trench disposal occurs by air drying (especially in the snow-free months), desiccation and draining over time once covered.

Drying and reduction of pathogenic microorganisms will be promoted within the portion of biosolids exposed to freeze-thaw action.

Four trenches will be developed over four years, and on the fifth year, the first trench, which has been covered for about three full years, will be excavated to provide a new

disposal trench. The excavated digested biosolids from the trench will be mixed with intermediate cover material and used for topsoil amendment in the final cover on closed areas of the landfill.

The trench method can be considered final disposal, if the solids are left in the trenches.

However, by excavating the stabilized biosolids from the trenches on a rotational basis, the amount of landfill area required to manage biosolids will be significantly reduced. Precipitation falling into the trench and water leaving the biosolids will infiltrate into the surrounding soil matrix. This water will be treated within the soil matrix system by natural biological and physical processes.

This simple sludge management system will be welcomed by the Dawson City staff since they are readying themselves for the operation of what will be a complex mechanical wastewater treatment facility.

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40 | Western Canada Water | Summer 2012

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30

THEME:

INNOVATION under pressure CRYOFRONT: News and Views from the Far North

Innovation gone wrong - the SH#%T hits the trailer park in Yellowknife

By Ken Johnson, NTWWA Director (From the memoirs of Jack Grainge entitled The Changing North. For many years, starting in the early 1950s, Jack worked with the Public Health Engineering Division of the Department of National Health and Welfare.)

Members of the crew took refuge in abandoned oil barrels that were lying on their sides near the shoreline. I stood on high ground about 50 metres away with my camera ready. Then the sludge blew. It rose about 35 metres high and the plume drifted about 40 metres downwind. It was then that I noticed that a slight breeze was blowing toward the nearby trailer park. The sludge made a layer of muck up to five centimetres thick. It stank horribly, a pigpen-like odour. The breeze was not strong enough to dilute the odour, but carried it gently toward the trailer park. The secretarytreasurer received a phone call from a lady in the trailer park, who asked, “How would you like to be served pooh for breakfast?�

The sludge plume was high, the stink was high, but it was not a highpoint in my career.

Over the years, the distance of the far-flung dung increased five-fold. One housewife claimed it landed on white shirts on her clothesline.

The following year, a backhoe was available and hired to excavate a deep hole at the sewer outlet. The algae green colour returned to the water in the lake. Nevertheless a larger lagoon was still necessary.

In all shallow lakes, dead algae sink to the

In 1964, the Niven Lake sewage lagoon in Yellowknife had lost its summertime algae-green colour for a wide area around the sewage inlet and become a drab, gray colour. Also, a 20-cm.- high island of sludge had developed near the sewage inlet. This part of the lake, only 200 metres from a trailer park, was beginning to stink. However, if a deep hole could be excavated to trap the sludge, the odour would be reduced. Unfortunately, there was no dragline in Yellowknife to excavate the hole.

The public works crew and I put our heads together, but this turned out to be a case where a few heads were not better than one. One of the crew had previously been a hard-rock driller at Giant Mine. He claimed that he could dynamite a deep hole in the bottom of the lake. He would drill and set the charges by the end of the day. I did not sleep well that night. I kept wondering how an ex-hard-rock miner had induced me to dynamite soft sewage sludge.

The next morning the crew gathered around the proposed blast site. I worried even more when I saw the ends of about 25 three-metrelong rods sticking up all over the island of sludge. I wondered how the shallow dynamite could create a deep hole. The driller maintained the dynamite would make a deep hole.

C H2O

Capital H2O Systems, Inc.

Sludge is launched 35 metres into the air by an explosion at the Niven Lake lagoon in 1964.

bottom, eventually becoming a thick layer of muck and the lake becomes a slough. During the 1970s, the heavy flow of nutrient-rich sewage caused this to occur at the lower end of Niven Lake. If the muck were excavated and allowed to decompose for two years, it would have made fertile soil for gardens, valuable in Yellowknife.

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32

THEME: Project Delivery

CRYOFRONT – News and Views from the Far North

Project delivery in the Far North - then and now

By Ken Johnson, NTWWA Director

A century after what many consider to be the greatest ‘event’ in the far north, the Klondike Gold Rush, it is interesting to reflect on the delivery of projects during that era, and in our so-called modern age.

A Gold Rush era project that is fresh in my mind, is the Yukon Ditch, which was a $3 million (1909 dollars), 115 km, flume, ditch and pipeline project designed to deliver 5,000 miner’s inches of water (3500 litres per second) for hydraulic mining. The following excerpts from a site visit in 1909 by an engineer, indicate the challenges with project delivery at the time.

“The magnitude of the work accomplished by the engineers of the Yukon Gold Co. may

be inferred from an enumeration of the tasks completed during the three seasons since the first surveys were finished – a power-plant of 2,000 HP, with 35 miles of main (power)line, 18 miles of branch, and 8 miles of secondary lines; 64 miles of main ditch, flume, and pipe. All this has been done 3,500 miles distant from manufacturing centres, with an inadequate supply of labour. Some of the machinery that arrived had been ordered 18 months previously. During the season of 1907, over 7,000 tons of material was received, and it was inevitable that some of the parts ordered in advance, for immediate operations, should be delayed in delivery despite every effort. A sufficient stock of parts

is carried, so as to obviate delays from slowness of transport. Maintenance of a proper commissariat for labourers required some generalship.

An effort was made to overcome the uncertain supply of local labour by importing 320 men from British Columbia. Of these, 20 deserted on the way.”

Dawson City and in fact much of the area ‘north of 60’ remains a project delivery challenge. This has been recognized by northern practitioners for over 25 years, and the cycle for project delivery is generally laid out in a 5 year ‘plan.’

The first year of a project is utilized for project planning. This is a necessary, but often time

33 48 | Western Canada Water | Winter 2011

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THEME: Project Delivery

consuming and expensive step to establish the required lines of communication between the various groups involved in the project, and to refine the project needs, and project resources.

The time and expenses are due to the isolation of project site, and the cultural differences of the project users. A simple visit to a project site may take a least a day or two of travel each way and cost thousands of dollars.

The second year of a project schedule is utilized for preliminary engineering and detailed design. These technical stages of the project may be characterized by the various technical activities with typical ‘southern’ engineering. However, the design criteria include careful consideration of cold temperatures, ice and snow, and how these are influenced by wind, darkness, and isolation.

The third and potentially fourth year of a project is utilized for project construction.

Construction of roads, pipelines, reservoirs, and lagoons is limited to a window between June and October. Construction before or after this period is certainly possible, but the cold temperatures often create problems, which may jeopardize the integrity of the project.

Projects in the coastal communities in the far north are faced with the problem that material and equipment supply cannot occur until late July, at the earliest. This is due to the fact that arctic waters are not free of ice until the mid-summer to allow the annual sealift to occur. Airlifting of materials and equipment is a last resort because it is extremely expensive.

Other projects, particularly in the western arctic, may have access to all-weather roads, or winter roads for material and equipment delivery. This allows for delivery during the winter months and for construction to begin as soon as temperatures permit.

The final year of the project schedule is post construction and warranty. This period of a project is not without its own particular problems, which may result from the ability of the contractor to complete deficiencies once his forces are demobilized, and the general ‘bugs’ that may have to be worked out of a newly completed project.

A century ago project delivery in the far north relied solely on water transportation for the delivery of construction materials. The SS Klondike plied the waters of the Yukon River until the late 1950’s delivering construction materials 800 km downstream to Dawson City. She is now a Parks Canada Historic Site in Whitehorse.

34 Click here to return to Table of Contents

Winter 2011 | Western Canada Water | 49

THEME: Project Delivery

IN THE NEXT ISSUE: Theme: SURFACE WATER MANAGEMENT In some respects, technology has not changed in 100 years because water transportation is still the only means of the construction material delivery in much of the north, as seen in the delivery of a package water treatment plant to the community of Taloyoak (Spence Bay), Nunavut. (Photo courtesy of BI Pure Water Inc.)

A significant portion of the Yukon Ditch was constructed using ‘steam’ shovels (see steam boiler in photo). These steam shovels were delivered in the vicinity of the project by sternwheelers and transported to the project site by horse drawn sleds (in many pieces of course). (Photo courtesy of Dawson City Museum.)

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Some fundamental aspects of project delivery in the far north have not changed in 100 years, although the technology applied in the project delivery has changed dramatically. Gone are the sternwheelers that plied the waters of the Yukon River to deliver construction materials and everything else to Dawson City and points in between. However, delivery by water, or ‘sealift’ remains a fundamental part of the project delivery process in the far north, particularly in Nunavut, where there are no roads providing access to the outside world.

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35 50 | Western Canada Water | Winter 2011

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36

Wastewater Sampling Challenges in Grise Fiord and Other Northern Communities Ken Johnson, M.A.Sc., P.Eng., AECOM Edited from 2007 2008 Summer Sampling Final Report, Canada Wide Strategy for the Management of Municipal Wastewater Effluent - Northern Research Working Group, Dillon Consulting Limited

Introduction The rollout of the Canada Wide Strategy for the Management of Municipal Wastewater Effluent continues to advance with the February 2010 announcement by Canada's Environment Minister that a draft of proposed municipal wastewater systems effluent regulations were available for public consultation. It was noted in the press release that "once in force, these regulations will set standards for the discharge from all wastewater facilities in Canada. Over time, wastewater facilities across the country will have to meet these national standards. It will no longer be permitted to directly release raw sewage into our waterways." The announcement failed to mention that the Northwest Territories and Nunavut did not endorse the legislation at the time of endorsement by the Yukon and the provinces in February 2009. A big gap remains in the practicality and fairness of this legislation for the far north regions of Canada, in particular the Inuvialuit Region of the Northwest Territories, Nunavut, the Nunavik Region of Quebec, and the Nunatsiavut Region of Labrador.

In fairness to the rollout of the legislation, a research program to quantify the performance of existing wastewater systems in the far north is on-going, and has a five year reporting mandate. However, in addition to the basic process performance challenges with northern wastewater treatment, the research program has identified a number of logistical challenges that may overshadow the actual implementation and monitoring of the legislation.

2008 Sampling Program Results The purpose of the 2007/08 sampling program was to identify the current wastewater treatment system configurations and performance in northern communities, where the proposed Canada Wide Strategy (CWS) for the management of municipal wastewater effluent may apply. The strategy includes national performance standards for the release of total suspended solids (TSS), and carbonaceous biochemical oxygen demand (CBOD) in wastewater effluent.

A total of 39 community were visited during the sampling program, 22 communities in the Northwest Territories, 13 communities in Nunavut, and 3 communities in the Nunavik Region of Quebec. In each community information was collected on the wastewater system, and wastewater samples were taken, when possible, in the various cells of the systems, and at the discharge of the system into the environment. These samples were tested for a full suite of chemical and biological parameters.

Sample results were analysed and compared to the proposed CWS effluent quality standards of 25 mg/L for TSS, and 25 mg/L for CBOD. The sampling results indicated that 16 of 25 wastewater effluent

37

samples collected (64 percent) DID NOT meet the proposed CWS standards for TSS, and 10 of 16 wastewater effluent samples (63 percent) DID NOT meet the proposed CWS standard for CBOD. A very interesting note to the sampling results is that the researchers identified that the "representative sites" should meet a variety of criteria which include:  

easy access to and from Yellowknife for prompt laboratory analysis of samples; and definitive and accessible sample locations for raw, primary secondary and final effluent

Sampling Timeframe and Temperature Challenges The report on the 2008 sampling program noted various challenges in acquiring representative wastewater samples in each of the communities of the study including meeting the laboratory "holding time" for time sensitive sampling, keeping the samples cool, access to the sampling locations and defining the location for obtaining representative samples, particularly the so-called "end of pipe."

"Holding time" is defined by the difference between the time of sampling, and the time at the beginning of the laboratory analysis. Bacteriological analyses must meet a maximum 24 hour holding time, and BOD and CBOD analyses must meet a maximum 48 hour holding time. Most communities in the NWT and Nunavut are difficult to access for the purpose of sampling because planes only fly and out on certain days of the week, and seasonal weather can isolate a community for days at a time. A related challenge to getting a sample back to the lab within the maximum holding time required by CBOD, BOD and bacteriological analyses is that samples sometimes need to be taken at odd hours of the day (or night) in order to "catch the plane."

Most water samples require cooling between the time of sampling and the time at the beginning of the analysis. The reason for lowering the temperature is to reduce any ongoing biological or chemical activity that would normally occurs in a sample, which will change the composition of the sample. By cooling the sample, the lab results should reflect the composition of the water sample at the time of the sampling. When samples arrive at laboratory, they are placed in a refrigerator holding room that is maintained close to 4 C. While in transit between community and laboratory, samples are placed in a cooler with ice packs to reduce the temperature.

In order to ascertain how consistently cold temperatures were maintained throughout the longest transit period in the 2008 study, temperature monitors called "thermistors" were placed in the sample coolers originating from Grise Fiord, Nunavut .

The temperature spikes that reached 10 C occurred when the sample cooler was opened to put in more waste water samples.

Sampling Access Challenges Accessing wastewater sampling locations was a definite challenge for the 2008 study . Many locations were either completely inaccessible or very difficult to access. Notably 22 % of the communities did not have access to the receiving water body of the wastewater system effluent.

In addition, the location of the end of pipe is still not clearly defined in CWS, and samples were taken at the likeliest location of the end of pipe. Many of the community samples had a wetland treatment as

38

part of their treatment process, therefore the end of pipe was not clearly defined, creating a challenge to identify and access to the final discharge point . For the majority of the samples taken from 39 community, there was not a clear a location for the end of the effluent discharge pipe.

Conclusions Biological systems at the mercy of the natural environment (such as sewage lagoons, and wetlands) are inherently variable regardless of latitude. If excessive cold temperatures are thrown into the mix, then biological systems are inherently unreliable for consistently meeting a prescribed low target, such as the CWS guidelines. The results from the 2008 sampling study clearly demonstrate this fact, with over 60 percent of the samples not meeting the CWS standards for TSS and CBOD. The logistical challenges for moving "stuff" around the north is intuitive for anyone who has done work in the north. A minimum 5 day timeline for transporting wastewater samples from Grise Fiord was documented. Temperature variations that "bounce all over the place", were also documented and these temperatures are well outside the criteria for valid process monitoring within the CWS framework.

This information alone challenges the validity of using the CWS standards in the north. Add to this mix the reality that only 50 percent of the sampling points are accessible, and the argument against the current CWS framework in the far north is strengthened.

39

Figure 1. Sewage lagoon in Grise Fiord, Nunavut – Canada’s most northerly municipal wastewater treatment facility.

Figure 2. Travel journey for wastewater sample from Grise Fiord temperature showing time and temperature.

Figure 3. Sewage lagoon in Ulukhaktok (Holman), NWT.

Figure 4. Accessibility of lagoon sampling points across the north.

40

WCW Conference & Trade Show  Calgary  September 21 – 24  2010

FORT RESOLUTION WASTEWATER MANAGEMENT STUDY Tricia Hamilton, AECOM Ken Johnson, AECOM ABSTRACT In response to concerns expressed by community members, community stakeholders, and regulatory authorities, the GNWT retained AECOM, to complete a wastewater management planning study in Fort Resolution. The concerns with the wastewater management were the capacity and environmental impact of the existing system, as well as the requirements and cost for improving and replacing the existing system.

The existing sewage lagoon system is a facultative/infiltration process consisting of six cells linked by channels. Wastewater ultimately percolates through the sandy soil in a northerly direction to the wetlands approximately 400 metres from site. Detention in the lagoon, and the infiltration process through the sandy soil provides treatment of the wastewater.

The sewage lagoon is approaching the end of its service life with its current configuration, as indicated by decreasing available freeboard. To meet the 20-year wastewater generation demand, a new lagoon should be constructed using the same facultative/infiltration process as the current lagoon. The volume of the new lagoon should be approximately 18,000 m³, with a depth of 3 metres. The cost of the new facultative/infiltration lagoon is estimated to be approximately $900,000.

COMMUNITY INFORMATION The community of Fort Resolution is geographically situated on Resolution Bay and immediately south of the Slave River delta. It is located at 61° 10' 16" N latitude and 113° 40' 20" W longitude, approximately 145 km southeast of Yellowknife. Fort Resolution is accessible by road, and is approximately 160 km by road from Hay River.

The community is located approximately 160 metres above mean sea level and 4 metres above the Great Slave Lake. The land to the east and south of Fort Resolution has a gentle slope towards Great Slave Lake.

The surficial soils are mainly deltaic, however, to the north of the community this pattern is interrupted by several massive outcrops of limestone bedrock. Fort Resolution is within the southern margin of the discontinuous permafrost zone, and as such, shallow permafrost is expected in undeveloped, forest-shaded areas. The climate in Fort

41

WCW Conference & Trade Show  Calgary  September 21 – 24  2010

Figure 1. Fort Resolution Area Resolution may be characterized by long cold winters and short cool summers. The daily average temperature is -2.9 C. The July mean high is 21.1°C and the mean low is 10.6 C. The January mean high is -18.4 C and mean low is -27.6 C. Fort Resolution currently uses a waste management site (sewage and solid waste) located approximately 1.5 km north of the community centre. This site is located approximately 0.9 km east of the Fort Resolution airport, and this present-day site was first put in use in approximately 1979.

Raw water is pumped from Great Slave Lake through a submerged intake line into a wet well beneath the truck fill station; the truck fill station is located on the northwest edge of the community. The raw water is treated with a package water treatment plant before discharge into the water trucks which delivers approximately 80 m³/day of potable water to the community.

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WCW Conference & Trade Show  Calgary  September 21 – 24  2010

Surface water runoff south of the airport ridge will likely discharge into Resolution Bay, and north of the airport ridge will discharge into Nagle Bay. Both bays ultimately discharge into Great Slave Lake.

A subsurface hydrogeological drilling investigation was conducted in the vicinity of the current waste site in 1992. Piezometers were installed to monitor and sample groundwater, and the water depth was found to be 1 to 2 metres below the ground surface. The soil characteristics were reported to be fine-grained sand for the first 3 metres below grade, sand and with silt layers to from 3 to 6 metres, and clay with sand and silt below 6 metres. The results of this hydrogeological investigation concluded that the groundwater flow gradient is toward the wetland located some 500 metres north of the waste site. The report also concluded that effluent flow from the lagoon into the groundwater system should take approximately 12 years to reach the wetland north of the waste site.

SEWAGE INFRASTRUCTURE The sewage collection in Fort Resolution is contracted out with an annual contract value of approximately $150,000. Sewage is collected from 225 buildings around Fort Resolution and trucked 1.5 kilometres to the current lagoon site. The sewage is then emptied into the laoon at the truck dump on the north side of the lagoon. Approximately 12 to 15 trucks with 9,100 litres of sewage are collected in the community each day, five days a week.

Fort Resolution's sewage lagoon operates as a facultative and infiltration (soil absorption) lagoon. In the warmer seasons, while retained in the facultative lagoon, sewage will undergo biodegradation by bacteria, algae and plants. Sun and wind-mixed oxygen near the surface of the lagoon permit photosynthesis and aerobic (oxygen-consuming) reactions. Anaerobic (oxygen-deficient) degradation can also occur in deeper areas of the lagoon.

Due to the porous, sandy soils around Fort Resolution's lagoon, sewage flows down into the soil matrix and may percolate through the unsaturated soil layer into the saturated soil (groundwater). The wastewater will then enter the groundwater flow. As sewage infiltrates through the soil, treatment occurs.

43

WCW Conference & Trade Show  Calgary  September 21 – 24  2010

Figure 2: Infiltration Lagoon The unsaturated zone is the layer of soil between the ground surface and the water table.

This zone has efficient treatment capabilities through filtration, biodegradation, absorption and adsorption; these processes will decrease coliform bacteria, biodegradable material, nitrogen and phosphorous. Studies suggest that the ideal unsaturated zone is between 0.9 to 1.2 metres of soil. However, a significant reduction of coliform bacteria has been measured in approximately 30 centimetres of unsaturated soil.

The saturated zone is the wet soil below the groundwater level. The saturated zone also facilitates treatment through filtration, biodegradation, absorption and adsorption, although not as efficiently as the unsaturated zone. In addition, denitrification may also occur, where organic carbon is available.

The groundwater table at the Fort Resolution site is very high; therefore the available unsaturated soil depth is limited. However, the saturated soil zone is extensive, both below the lagoon site, and to the north of the lagoon site toward the wetland area.

Ultimately, the saturated flow discharges to a wetland system approximately 400 metres north of the sewage lagoon over a time period of approximately twelve years. This wetland system ultimately discharges into Nagle Bay, and from there into Great Slave Lake.

Fort Resolution's sewage lagoon consists of a series of six cells. The first cell (the most northerly) was excavated in approximately 1979, and additional cells were sequentially excavated to the south during the history of the site usage (1979 – 1981, 1985 – present), whenever the lagoon appeared to be reaching capacity or when fill material was needed.

The cells were constructed using an excavator; after a cell was constructed, a channel was excavated to connect the cell to the rest of the lagoon system.

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WCW Conference & Trade Show  Calgary  September 21 – 24  2010

Figure 3. Fort Resolution Sewage Lagoon Configuration Based upon the population projection outlined, the generation of sewage waste is estimated currently to be 77 m³ per day and in 20 years the generation rate is estimate to be 84 m³ per day.

Wastewater generated in Fort Resolution is primarily domestic in source and characteristics. The wastewater quality from the community may be considered to be a "high strength" waste because of the use of a trucked sewage and water system. The "high strength" condition is typical for trucked sewage and water systems due to the low water usage, which results in a low dilution of the raw sewage.

45

WCW Conference & Trade Show  Calgary  September 21 – 24  2010

Table 1: Wastewater Characteristics of the Sewage Lagoon Fort Resolution Sewage Lagoon Parameter 5-Day Biochemical Oxygen Demand (BOD5) Total Suspended Solids E. Coli Total Coliforms Ammonia-N pH

Unit

Truck Dump (2008)

Cell 6 (2008)

mg/L

421

151

mg/L MPN/100 mL MPN/100 mL mg/L pH Units

224 1,600,000 >1,600,000 66 7.2

190 110,000 1,600,000 23.8 7.4

From the truck dump in Cell 1 to Cell 6, the sample analysis demonstrates a 93% reduction of E Coli; a 64% reduction in BOD5; a 64% reduction in ammonia; and a 15% reduction in suspended solids. The relatively low reduction in suspended solids is a result of the algae growth in the lagoon, which is responsible for the BOD5 and ammonia reductions.

These reductions in BOD5, suspended solids and coliforms demonstrate that the retention in the facultative lagoon contributes significantly to the overall wastewater treatment process.

A water sample was collected from standing water in the area north of the lagoon, prior to the wetland system, which may be representative of groundwater characteristics as the sewage lagoon effluent ultimately discharges into the wetlands. The laboratory analysis for this sample is presented in as "Surface Water Near Wetland".

The BOD5 and nitrogen (in the form of ammonia) concentrations for the truck dump and for Cell 6 are included in Figure 4 for comparison purposes, and are representative of the wastewater quality before the effluent infiltrates into the soil. The BOD5 and ammonianitrogen values may be indicative of the potential impact of the sewage lagoon on the groundwater system as the groundwater moves toward the wetland.

46

WCW Conference & Trade Show  Calgary  September 21 – 24  2010

450

421

Concentration (mg/L)

400 350 300 250

BOD5

Ammonia Nitrogen

200

151

150 100

66

50

24

36

19

0 Truck Dump (2008)

Lagoon (Cell 6) (2008)

Groundwater Average (1992)

4

0

Surface Water Near Wetland (2008)

Sample Location

Figure 4: BOD5 and Nitrogen in Ammonia Concentrations These results indicate a significant overall nitrogen removal from the lagoon system through the groundwater system, as well as significant removal from the groundwater average around the lagoon to the surface discharge near the wetland. The results also indicate a significant reduction in the BOD5 value from the groundwater average concentration to the surface water concentration, demonstrating that significant degradation occurs as wastewater travels down gradient with the groundwater.

It should be noted that these observations are based upon a very limited number of samples, two samples taken from the lagoon in 2008, an average of groundwater samples in 1992, and one sample of standing water (representative of groundwater conditions discharging into the wetlands) in 2008.

The existing sewage lagoon configuration is nearing the end of its operating capacity.

From site observations of freeboard (distance from the water level to the top of the lagoon pond) at the truck fill station on June, 2008, there was approximately 0.55 metres of freeboard remaining in the lagoon.

LAGOON DEVELOPMENT Fort Resolution’s current sewage lagoon is nearing the end of its capacity, and Fort Resolution requires a new sewage lagoon. While desludging the current lagoon would remove some biosolids, it would not effectively remove the interface of sludge

47

WCW Conference & Trade Show  Calgary  September 21 – 24  2010

preventing sewage from infiltrating into the ground. Excavating a new lagoon cell in the existing system will extend the life span of the current lagoon, but after that time infiltration rates will once again slow and the community will once again have to address this problem.

Fort Resolution’s sewage lagoon was excavated with limited engineering consideration.

Cells have been excavated when the lagoon nears capacity or when fill material is required. This is a problematic method of operating a sewage lagoon facility.

Facultative / Infiltration Lagoon The efficiency of an infiltration sewage lagoon decreases over time due to sludge buildup. Solids settle in the bottom of the lagoon, forming a low permeability barrier that reduces the available surface area for wastewater to infiltrate into the surrounding soil.

The sludge should be periodically removed from the lagoon ('desludged') to allow better infiltration of the lagoon.

Figure 5: Two-Celled Infiltration Lagoon With Cobble Berm One method of reducing the impact of sludge build-up in a lagoon is to have a 'settling cell'. This is a lagoon system consisting of two engineered lagoon cells, where the smaller, first cell provides retention time for solids in the sewage to settle before flowing to the second cell, where infiltration occurs.

Due to the cold northern climate, having the cells be connected with a pipe or channel is problematic. A cobble berm separating two cell will reduce the risk of freezing blockage over winter. The top of the cobble berm will be below the outside perimeter, to allow sewage to travel over the cobble berm into the second cell should the permeability of the cobbles be reduced. This design will lessen the impact of sludge build-up on infiltration rates, and desludging may only be required in the first cell.

48

WCW Conference & Trade Show  Calgary  September 21 – 24  2010

A geotechnical and engineering investigation is required to determine the depth to groundwater and verify hydraulic loading rates. To allow for wastewater to percolate through the unsaturated soil matrix, the lagoon should not intersect the groundwater table.

The sewage lagoon should be at least 30 centimetres above the groundwater table. Thus, the lagoon may have to be extended above ground through use of berms.

Lagoon Sizing As infiltration rates are expected to significantly decrease during colder months, the lagoon must be sized to be able to retain the community’s wastewater production for seven months from October until April. Wastewater infiltration is expected to primarily occur in the warmer months from May until September, the projected 2027 sewage production of 30,702 m³ (2027 annual generation rate) must have the capacity to infiltrate into the soil over five months.

Thus, the lagoon must have a capacity of at least 17,910 m³ to be sized for 20 years (2027). For aerobic treatment of sewage while retained in the lagoon, the lagoon should be no more than 3 metres deep. As such, to provide a volume of 17,910 m³, an area of at least 5,572 m² is required.

The hydraulic loading rates of the soil at the Fort Resolution waste site was determined to be in the range from 1.7x10-5 cm/s (0.0147 m³/m²day) to 4.6x10-3 cm/s (3.97 m³/m²day). The average loading rate of 6.7 x 10 4 cm/s (0.58 m³/m²day) is used for this calculation.

Due to higher solids content, wastewater loading rates are estimated to be between 10%15% of hydraulic loading rates. An average of 12.5% of the hydraulic loading rate was assumed for the wastewater loading rate for Fort Resolution. Therefore, the wastewater loading rate is estimated to be 8.38 x 10-5 cm/s (0.0725 m³/m²day).

The annual loading rate is calculated by multiplying the wastewater loading rates by the number of days infiltration is anticipated to occur (May until September). Thus the annual loading rate is predicted to be 11.03 m³/m² year. Given that the annual sewage production in 2027 is predicted to be 30,702 m³, to provide sufficient infiltration capacity the lagoon must be at least 2,783 m².

A 3 metre deep infiltration lagoon with a volume of 17,910 m³ and an area of 5,970 m² should provide sufficient volume and area for cold weather retention and warm weather infiltration of Fort Resolution's wastewater.

If the settling cell is 10% the volume of the infiltration cell, the settling cell should have a volume of 1,791 m³ and an area of 597 m².

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WCW Conference & Trade Show  Calgary  September 21 – 24  2010

Thus, the size recommended is a 3 metre deep lagoon with a volume of 17,910 m³ and an area of 5,970 m². The actual length and width of the lagoon can be selected to best account for site conditions and tree clearing requirements.

CONCLUSIONS AND RECOMMENDATIONS Fort Resolution's sewage lagoon, composed of six cells excavated as required, is nearing capacity with very little freeboard. The current site has successfully operated for approximately 25 years and there is plenty of available land space in the area. A redevelopment of the current site and improved operation and maintenance practices may address community concerns regarding the site location.

Water samples were obtained during the course of this study, and it was observed that while retained in the lagoon there was a significant reduction of E Coli, BOD5 and ammonia concentrations. Groundwater and surface water samples suggest a significant reduction in nitrogen and BOD5 concentrations attributed to the infiltration process.

Wastewater from the lagoon experiences aerobic treatment while retained in the lagoon, infiltrates the sandy soil, where treatment occurs in the soil matrix, and enters the groundwater flow to the wetlands approximately 400 metres north. During retention time in the wetlands, further treatment occurs due to natural biological activity and settling.

As the soil in Fort Resolution is porous sand historically capable of handling the loading of the community's sewage which discharges with the groundwater into a wetland, a facultative/infiltration lagoon is recommended. A facultative/infiltration lagoon is also less expensive ($0.90 M) than a retention lagoon ($1.7 M).

50

Giant Mine Water Management System Ken Johnson, AECOM NOTE: This project received the prestigious Award of Excellence from the Consulting Engineering of Alberta as part of the Showcase Awards 2010 History of Yellowknife Gold Mining The history of Yellowknife is intrinsically linked to its start as a mining town. When gold was discovered on the shores of Great Slave Lake and the claims were staked, Yellowknife was born as gold mining boomtown. The two most longstanding and productive mines, the Con and Giant Mines, were a result of the original exploration. Con closed underground operations in 2003 after 65 years of production and Giant closed underground operations in 2005 after 60 plus years of production. Both mines have left significant legacies on the shores of Great Slave Lake.

The rock mined at Giant is rich in gold and arsenopyrite, a mineral that has a high arsenic content. The gold extraction process used at Giant required a „roasting‟ process to extract the gold from arsenopyrite rock. Arsenic trioxide dust was created during the production of more than seven million ounces of gold between 1948 and 1999. When the ore was roasted to release the gold, arsenic was also released as a gas. As the gas cooled, it became arsenic trioxide dust.

Over a fifty year period 237,000 tonnes of toxic arsenic trioxide was produced, which is still being stored to depths of nearly 250 metres (800 feet) below ground in various shafts and chambers.

Arsenic trioxide is water soluble containing approximately 60% arsenic, therefore it is critical to maintain the stored material “high and dry” to ensure that arsenic is not released into the environment. This effort requires that the groundwater be maintained below the 250 metre level through an automated dewatering pumping system.

Managing the Giant Mine Arsenic Trioxide Almost all of the arsenic trioxide at Giant Mine is stored in 15 underground chambers and stopes (irregular, mined-out cavities) cut into solid rock. Concrete bulkheads, which act as plugs, seal the openings to these chambers and stopes. The arsenic trioxide dust is totally surrounded by solid rock.

Due to the extensive mining, the permafrost around Giant thawed, and water began seeping into the storage chambers, becoming contaminated, with the potential of entering the groundwater systems. In response to this new issue, the water is pumped from the mine to a treatment facility on the surface. The contaminants in the water are removed through a treatment process before the water is released into the environment.

51

When this underground storage method was originally designed, it relied on the area's natural permafrost, which worked as a frozen barrier. It was believed that when the time came to close Giant Mine, permafrost would reform around the storage chambers and stopes, and seal in the arsenic trioxide. A 1977 report by the Canadian Public Health Association concluded that the underground storage of arsenic trioxide dust at Giant Mine was acceptable.

When the mine permanently closed some stakeholders wanted the arsenic trioxide removed from the mine and shipped elsewhere, away from Yellowknife's 18,000 residents. Citing risks to workers and the environment, INAC settled the solution of reestablishing the permafrost around the underground chambers and into a big deep-freeze, locking the dust into an eternal deep freeze. Integral to what is referred to as the "Frozen Block Alternative" is the automated dewatering pumping system to maintain the groundwater below the underground chambers.

In 2005, AECOM was retained by Public Works and Government Services Canada to provide planning and design of a new mine de-watering pumping system for the Giant Mine.

With the mine closure, cleanup and remediation efforts have been completed in the lower portions of the underground works and it is no longer necessary to keep the mine dewatered below the 850ft. level. Water enters the mine as groundwater seepage and surface run off. The mine water level is held at the 850 ft. level by the automated mine de-watering pumping system.

De-watering System Hydraulics and Pumping Mine de-watering is maintained by pumping the mine water from the 850ft level to surface at the historic Akaitcho headframe, in two separate pumping lifts. The lower lift portion of the pumping system uses a duty standby set of parallel submersible pumps installed within HDPE carrier pipes in an inclined mine shaft. These pumps lift water approximately 30 meters to a sump located on the 750ft. level of the mine. The sump is configured to provide “dirty” and “clean” cells by using a series of concrete weirs placed across an abandoned mine drift. This sump provides a suction volume to the high lift pumping system that moves water from the 750 ft. level to the surface in a single lift. Once at the surface the water flows to a retaining pond for subsequent treatment. The high lift pumping system uses a duty standby set of parallel 250 hp. multi-stage centrifugal pumps. Both the low lift system and the high lift systems are matched in pump capacity in order to provide a total de-watering flow rate of 275 cubic meters /hr.

Construction of De-watering System The mobilization of materials to the project site up to 850 feet below the ground surface was a major challenge, particularly since the mine is no longer in full operation The contractor responsible for the work was Deton Cho / Nuna. which also has the “Care and Maintenance” contract for the mine. Construction of the sloped sections of the water line from 850 feet to 425 feet would have been a routine exercise for pipe fitting contractors, however, the contracting resources available for the work were ex miners, therefore the work

52

proceeded slowly in the initial part of the project. As the work advanced, the contractor employed pipe fitting expertise and the work progressed much faster.

Construction of the vertical section from 425 feet to the ground level was difficult because it required construction from the bottom up, which meant that 6 metre pipe sections were lowered down the Akaitcho Shaft and sequentially added to the lower section and supported to the shaft wall. Access for this section of the work was challenging for the contractor because all of the steps and landing down to 425 feet were wooden construction dating back to the 1950â€&#x;s in some cases.

Commissioning the dewatering system was held to a critical milestone of catching the spring runoff inflow. The work was ultimately completed in November, 2008 for a total cost of $3,000,000 (CDN).

53

Figure 1. Akaitcho Headframe at the top of the Akaitcho Shaft where highlift pumping system exits mine

Figure 2. Access vehicle and access shaft to Giant Mine

Figure 3. Section of lowlift pipeline

Figure 4. Profile of Giant Mine water management system 54

WCW Conference & Trade Show  Calgary  September 21 – 24  2010

UTILIDOR REPLACEMENT IN INUVIK, NWT Ken Johnson, AECOM

ABSTRACT The Town of Inuvik is Canada’s largest community north of the Arctic Circle, and has a unique history as the first completely "engineered" northern community. According to some, there has never been a Canadian town so “pondered, proposed, projected, planned, prepared and plotted” as East-3, which was its original site identification back in the 1950’s. The notable aspects of Inuvik’s townsite that continue to challenge engineers include long, very cold winters, permafrost, and great distance from sources of supply.

The built environment of Inuvik must cope with the permafrost, and the extreme cold for buildings, water, sewer, roads and drainage; each of these elements requires unique design and construction considerations.

The water and sewer mains that service each building are aligned along the back of each lot; the cost of these services is about $50,000 per lot or about $5,000 per metre. The service connections exit above ground from each building and resemble a large “metal centipede” as they connect to the water and sewer mains. Much of the water and sewer infrastructure is now almost 50 years old, and is at the end of its design life. A program to replace the water and sewer has been ongoing for the past 15 years, and will continue for many years into the future.

BACKGROUND The Town of Inuvik is Canada’s largest community north of the Arctic Circle, (68° 22' N latitude, and 133° 44' W longitude) and has a unique history as the first completely "engineered" northern community. According to some, there has never been a Canadian town so “pondered, proposed, projected, planned, prepared and plotted” as East-3, which was its original site identification back in the 1950’s. Inuvik was planned and engineered by the Canadian government in the late 1950’s to replace the flood-prone Aklavik, 50 kilometres to the west, as the region’s administrative centre. Canadian Prime Minister John G. Diefenbaker dedicated Inuvik as "The first community north of the Arctic Circle built to provide the facilities of a southern Canadian town. It was designed not only as a base for development and administration, but as a centre to bring education, medical care and new opportunity to the people of the western Arctic."

The site for Inuvik was chosen for its elevation above the Mackenzie River flood zone, abundant gravel deposits, ample space for an airport, freshwater lakes and navigable waters. The community sits on a broad terrace between the East Channel of the

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WCW Conference & Trade Show  Calgary  September 21 – 24  2010

Mackenzie River, and the upland that forms the present-day Mackenzie Delta’s eastern boundary. The Mackenzie Delta is the largest delta in Canada; it is 210 kilometres long and an average width of 62 kilometres, occupying 13,000 square kilometres.

The July mean high and low temperatures in Inuvik are 19.7°C and 8.2°C. The January mean high and low temperatures are -26.1°C and -35.7°C. The average yearly temperature is -9.6°C. The total yearly precipitation average is 276 mm with 110 mm of this occurring as rainfall.

Inuvik originally developed with a reasonably compact and efficient downtown business core just east of the East Channel. Primary and secondary schools were located on large blocks of land between the downtown core and surrounding residential areas. A large regional hospital was sited at the south end of the townsite. The residential areas radiate outward from the central core area, and there is a considerable amount of undeveloped space between the current margins of developed residential districts and the perimeter collector road. Inuvik acts as its own developer of serviced land for townsite expansion, undertaking both financing and administrative work itself in order to supply serviced lots at the lowest cost reasonably achievable.

Inuvik grew steadily in the period of 1961 to 1986, from 1,200 people to 3,570 people.

The population increased significantly in the mid-seventies along with the gas and oil exploration at the time. When the exploration activity declined in the late seventies, the population also declined a bit from about 3,100 people to 2,900 people. In the period of 1986 to 2004, the population of Inuvik dipped to around 3,400, with minor fluctuations until returning to the 1986 population of near 3,600.

Figure 1: Original Metal Box Utilidor System in Inuvik

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WCW Conference & Trade Show  Calgary  September 21 – 24  2010

The original water and sewer servicing scheme used an above ground metal “box” or “utilidor” which housed water, sewer and a high temperature hot water heating system.

The utilidor was supported on timber piles.

THE ENGINEERING AND DEVELOPMENT CHALLENGES The notable aspects of Inuvik’s townsite that continue to challenge engineers include long, very cold winters, permafrost, and great distance from sources of supply. Inuvik depends on southern sources for materials of all sorts, with the exception of drinking water. The built environment of Inuvik must cope with the permafrost, and the extreme cold for buildings, water, sewer, roads and drainage; each of these elements requires unique design and construction considerations.

The problem with permafrost is that it never completely melts, however in the summer the top metre or “active layer” may melt with the warm temperatures. The permafrost ground below Inuvik also “ice rich”, which means that when it melts, the ground may settle by hundreds of millimetres to fill the voids left by the melting ice. This magnitude of settlement can cause major structural damage to buildings and pipes. The heat from houses and water and sewer pipes may also melt permafrost, therefore all of the buildings and pipes in Inuvik are built on piles to provide a “thermal break” between the building and the ground.

The water and sewer mains, and power poles that service each building run along the back of each of the development sites. In most cases the utilidor is positioned in a dedicated right-of-way, but in some cases no right-of-way exists. The cost of these services is about $50,000 per lot.

The service connections exit above ground from each building, and resemble a large “metal centipede” as they connect to the water and sewer mains. Road crossings of the utilidor create another challenge because the road must literally bridge the utilidor, at a cost of nearly $50,000.

Inuvik’s methods of development access and site preparation have also adapted to the extreme conditions. Roads are built above the natural grade, with embankments thick enough to provide an insulating layer to minimize permafrost melting. Road grades and building lots are never excavated for pre-grading purposes, to avoid the effects of continuing thaw settlement, which can continue for several years in the developed or disturbed areas. Building lots are often filled, to provide grading for drainage, and a drivable access to construction vehicles, as well as to reduce thaw settlement. Drainage runs on the surface, in ditches, except where it passes through culverts under roads.

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WCW Conference & Trade Show  Calgary  September 21 – 24  2010

Figure 2: Modern Utilidor System in Inuvik The utilidor creates unique development and planning challenges because it is above ground. The minimum floor level in a building must be high enough to drain by gravity to the sewer utilidor. Road crossings of the utilidor create unique humps in the streets.

“Open” back yards are not very common in Inuvik because the utilidor service connections usually fill a portion of the yard.

UTILIDOR DESIGN Inuvik’s ground is thaw sensitive (warm) permafrost, which means that the temperature of the permafrost is only a few degrees below zero, therefore small variations in the ground temperature caused by excavation will cause the permafrost to melt. In addition, the ground is also "ice rich", which means there are significant pockets of ice that may thaw causing significant slumping in the ground.

The thaw sensitive soil is the primary reason for the above ground utilidor system. The first generation of the utilidor was built with timber piles. It was expected that the timber piles would last indefinitely because of the cold air and ground conditions. However, timber will eventually deteriorate if exposed to warm temperatures even for brief periods

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WCW Conference & Trade Show  Calgary  September 21 – 24  2010

of time in the north. Steel piles have been used for the past 20 years to replace the deteriorating timber pipes.

Figure 3: Pipe Support for Modern Utilidor System in Inuvik Piles support the utilidor, and thermal stability is maximized by placing the piles to a minimum of 6 metres into the ground. The piles are coated with heavy grease and wrapped with polyethylene to maintain a non-bonding surface between the ground and the pile for inevitable shifting of the ground. The piles are backfilled with a sand slurry which helps the bottom section of the pile freeze into the existing permafrost regime.

The pipe used for the sewer and water system of the utilidor is an insulated steel pipe with a metal jacket covering the insulation. For the steel pile utilidor, the water and sewer pipes are structural beams which carry the gravity loads of water, cement mortar lining, the pipes themselves insulation, jacket, fittings and snow and ice. A standard space of 7 metres has been chosen as a reasonable balance between pile capacity, beam capacity and pile frequency. The pipes are specified Schedule 80 (12 mm wall thickness) to provide corrosion resistance, in addition to the cement mortar lining.

In addition to the thermal concerns in the vertical direction, thermal movement is also a concern in the horizontal direction. With an operating temperature range from minus 50°C to plus 30°C expansion, and contraction and expansion of the pipe is significant.

The thermal considerations for horizontal pipe movement include either a bend, or an expansion joint every 25 to 30 metres along the pipe. Each pipe support at the piles is a roller system to accommodate the horizontal movements. The movement of the pipe is also controlled with line anchors every 60 to 80 metres.

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WCW Conference & Trade Show  Calgary  September 21 – 24  2010

The ultimate objective of the utilidor system is to provide water and sewer connections to individual buildings. To accomplish this, a service box is attached to the utilidor near each building, and water and sewer services run into the box and ultimately into the building through a common carrier pipe. The service box provides easy access to the service connection or "utilidette", and also provides a common space where heat from the system may provide additional freeze protection. The common carrier pipe for the water and sewer services accomplishes the same freeze protection objective.

Figure 4: Water and Sewer Service Connection to Utilidor System A similar configuration is used for hydrant servicing along the utilidor with hydrant boxes placed at intervals along the utilidor. The hydrant boxes are painted red for easy identification.

UTILIDOR CONSTRUCTION Initial site work for the utilidor projects for both extension of the system or replacement of the system includes: clearing and brushing of the utilidor alignment, temporary removal and replacement of private installations (replacement only), excavation to the subgrade of the utilidor, preparation work pad and drainage related work.

The minimum width of clear working area needed for a utilidor project is about 5 to 6 metres. About 4 metres is needed along one side of the pipe centerline for vehicle movement as well as the utilidor installation.

Where the pre-existing ground is to be graded down by more than 250 mm, the standard practice is to sub-excavate by a further 200 mm, and install 100 mm of rigid close cell insulation and bring the ground elevation back up to grade. The width of the insulated area depends on the grading cross-section but typically would be at least 4 m.

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WCW Conference & Trade Show  Calgary  September 21 – 24  2010

The potential thaw of permafrost is always an issue with any excavation, but it is less of a problem in the built up areas of the community. The excavation in built up areas is not likely to cause any significant lowering of the permafrost table and the accompanying ground subsidence because the thermally protective organic cover material was removed long ago and the permafrost has established a new equilibrium. However, deeper excavation has the potential to cause subsidence problems even in built up areas.

The utilidor system (water and sewer mains, pile system, service connections, hydrants, etc.) have historically cost about $50,000 per lot or about $5,000 per metre. This compares to a buried “utilidor” system, such as the one in Iqaluit, Nunavut, which costs about $1,500 per metre. These costs were based upon a local contractor in Inuvik with a long standing success at capturing utilidor work. This contractor retired several years ago and the most recent costs for the utilidor (2010 construction season) are $7,500 per metre.

Figure 5: Temporary Sewer Service for Utilidor Replacement Some of the individual cost components are: Piles Water main Sewer main Hydrant box Expansion joint

$3,000 each $1,000 per metre $1,000 per metre $6,000 each $7,000 each

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WCW Conference & Trade Show  Calgary  September 21 – 24  2010

Figure 6: Completed Pile Construction for Utilidor and Marking of Sewer Invert CONTINUING UTILIDOR CONSTRUCTION Utilidor replacement in Inuvik is a continuing project which ultimately depends upon the available capital funding. It is a very specialized system, and the only similar infrastructure occurs in Norman Wells, NWT, which is serviced in a portion of the community by an above ground utilidor. The complete replacement of the original utilidor system in Inuvik may take decades to complete, with a price tag of over a hundred million dollars.

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WCW Conference & Trade Show ▪ Winnipeg ▪ September 20 - 23 ▪ 2009

Sewage Composting in Iqaluit, Nunavut – Black Gold Ken Johnson Cortney McCracken AECOM ABSTRACT In the Canadian north, municipal sewage sludge has been virtually ignored because of the predominance of lagoon wastewater treatment systems. The application of mechanical sewage treatment systems in Nunavut, and an increased regulatory scrutiny over the past 15 years have created a demand for sewage sludge handling, treatment, and disposal. The City of Iqaluit, Nunavut has been working toward the implementation of a secondary sewage treatment system since 1998, and with it the need for sludge management. This is an ambitious goal for the community considering the inherent challenges to the design, construction and operation of facilities in the harsh arctic environment.

Conventional municipal sewage treatment uses physical, chemical, and biological processes to separate solids and biological contaminants from municipal wastewater. Solids in the sludge are typically processed in a digester system, in which biodegradable materials are “digested” into stable organic matter. Sewage sludge may be further treated through dewatering, heat drying, alkaline (lime) stabilization, composting, or other processes.

Freezing and thawing, as an efficient method of sewage sludge conditioning, has been used for many years in cold climates. The final separation is achieved when the “released” water drains away from the solids after thawing, leaving a porous sludge with solids content of 20 to 30%. Following this dewatering and drying process, composting may provide stabilization and destruction of pathogens. The composting process requires the addition of bulking materials such as wood chips and cardboard pieces.

The City of Iqaluit landfill facility has been able to divert sewage biosolids from the first phase of the wastewater treatment plant. The process for the biosolids is to dry the solids throughout the long winter making use of Iqaluit’s cold dry weather, and compost the dried solids during the short warm summers to produce a cover material for the landfill. This process is attractive because the finished material is non-hazardous, and will reduce the use of precious granular material at the landfill - granular material may cost over $40 per cubic metre in Iqaluit.

Managing sewage sludge through freeze-thaw-composting is not without its challenges, but the City of Iqaluit has successfully completed a pilot program. Where other municipalities take for granted the technologies available to them, the arctic must re-engineer the process to suit the environment.

WCW iqaluit paper KJohnson CMcCracken 090630 Page 1 of 11

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WCW Conference & Trade Show ▪ Winnipeg ▪ September 20 - 23 ▪ 2009

INTRODUCTION The City of Iqaluit, Nunavut is in the process of upgrading to a conventional activated sludge wastewater treatment system for its municipal sewage. The first phase of the project (primary treatment) was commissioned in May 2006, and the second phase (secondary treatment) is planned for the next five (5) to ten (10) years. The design, construction, and operation of this facility present challenges that are unique to Iqaluit’s harsh arctic environment. One of these challenges is how to dispose of the sewage sludge produced by the sewage treatment facility.

Sewage sludge, produced as a waste product during modern sewage treatment, has specific handling, treatment and disposal requirements. Sludge has high levels of pathogens and high nutrient characteristics, so sludge must usually be treated before disposal in order to protect public health and the receiving environment. Most municipalities in Canada are aware of the need to treat sewage sludge before disposal.

However, sewage sludge treatment in the Canadian north is not well established.

Municipal sewage sludge in the north is hidden as an inherent part of a sewage lagoon.

Sludge essentially becomes part of the lagoon as it settles to the lagoon bottom, and only requires removal every 10 (ten) to 15 (fifteen) years. With such infrequent sludge disposal, it is easy to ignore municipal sewage sludge entirely. In addition, sludge management techniques used in more southern climates are not necessarily effective in the Northwest Territories and Nunavut because of the challenging environmental and social conditions.

The City of Iqaluit recognized the need for a sewage sludge management plan, and initiated a study to identify available sludge management technologies, and then apply screening criteria to produce a short list of technologies for detailed evaluation. These technologies were reviewed for their applicability in a northern context, and it was recommended that freeze-thaw dewatering and composting was the most appropriate choice for Iqaluit.

With freeze-thaw dewatering and composting selected as the sludge treatment processes, the City applied for funding to begin a pilot project in order to determine how effective the technology would actually be for Iqaluit's sewage sludge. The Federation of Canadian Municipalities (FCM) approved the City's grant application for equipment and testing. A pilot dewatering and composting facility was constructed next to the landfill in 2006.

Following through on the FCM grant the City of Iqaluit needed to determine the effectiveness of the sludge management pilot project. It was proposed to do this by analyzing samples of the compost and comparing these samples to the raw sludge. To this end, composted sludge samples were taken from the pilot sludge management area in October 2008, along with raw sewage sludge samples from the site. Samples of Iqaluit's raw sewage sludge were also taken in March, May and June of 2006.

WCW iqaluit paper KJohnson CMcCracken 090630 Page 2 of 11

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WCW Conference & Trade Show ▪ Winnipeg ▪ September 20 - 23 ▪ 2009

SLUDGE COMPOSTING PROCESS The sludge management facility is located next to the municipal landfill. Raw sludge is piled at the east end of the site, and four (4) composting piles (windrows) are established on concrete slabs towards the west end of the site. The area is fenced, with two gated entrances: one direct access through a gate from the road on the west side of the site, and an access road from the main gate at the landfill entrance.

Freezing and thawing is used to dewater the raw sewage sludge. During spring and fall months, the sludge freezes and thaws, which separates the solid sludge particles from the water. When complete thawing occurs from May to June, some of the separated water drains away. This freeze-thaw process produces a dryer sludge material available for composting.

To begin the composting process, dewatered sludge is mixed with wood chips (produced by shredding) at a ratio of approximately 2:1 wood: sludge, and piled in rows. The compost should be turned regularly to encourage aerobic conditions inside the pile. Over the summer months, composting will occur, and a "maturing" phase can occur over the following winter months.

SAMPLING RESULTS 2008 Samples On October 28, 2008 samples of raw sludge and composted material were collected from the City's sludge management facility. Figures 1 and 2 show the sampling locations.

Figure 1: 2008 Sample Locations

Sludge #1

Compost #1 Compost #2

Compost #3

Sludge #2

The sample results were received by AECOM on November 11, 2008.

Table 1 shows the results for the 2008 compost and sludge samples.

WCW iqaluit paper KJohnson CMcCracken 090630 Page 3 of 11

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WCW Conference & Trade Show ▪ Winnipeg ▪ September 20 - 23 ▪ 2009

Figure 2: Iqaluit Pilot Sludge Management Site Overview Table 1: October 2008 Sample Results Parameter

Unit

Compost #1

Aggregate Organic Constituents % 10.8 Organic Matter weight % 32.1 Water % 67.4 Solids % 0.68 Oil (dry wt.) % 0.46 Oil (wet wt.)

Classification 0.35 Nitrogen (TKN) % mg/kg 1620 Phosphorus Microbiological Analysis MPN/g <3 Total Coliforms 1

Compost #2

Compost #3

Sludge #1

Sludge #2

8.3

8.6

84.2

91

0.29 1410

0.32 1470

0.35 2090

0.28 1340

7

43

>1,100,00

23000

The low organic matter result for Sludge Sample #2 may be an anomaly.

WCW iqaluit paper KJohnson CMcCracken 090630 Page 4 of 11

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WCW Conference & Trade Show ▪ Winnipeg ▪ September 20 - 23 ▪ 2009

Parameter

Fecal Coliforms

Unit

MPN/g

Compost #1 <3

Physical and Aggregate Properties % 55.7 Solids (wet wt.)

Soil Acidity 7.4 pH 5.66 EC (sat. paste equiv) 2.75 EC (soil: water) Water Soluble Parameters mg/kg 3400 BOD (extractable)

Compost #2

Compost #3

Sludge #1

Sludge #2

23000

44.8

7

7

0 1,100,000

56.2

60.9

19.6

104000

2006 Samples Initial samples of raw sludge from Iqaluit (the WWTP or the sludge management site) were taken in March 2006, May 2006, and again in June 2006.

The conclusions from this sampling were: 1. Untreated Iqaluit sludge has a high concentration of total solids (around 20%) compared to typical primary sludge (around 6%).

2. Untreated Iqaluit sludge contains a high concentration of Total Coliforms and Fecal Coliforms, with >1,100,000 MPN/g measured for both parameters in both the March and June samples.

3. Untreated Iqaluit sludge contains a low concentration of metals compared to typical wastewater sludge.

The sludge sample taken in March 2006 was analyzed for many different parameters, including various trace metals. The results can be compared to those of the Compost #1 sample taken in 2008, as shown in Table 2.

WCW iqaluit paper KJohnson CMcCracken 090630 Page 5 of 11

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WCW Conference & Trade Show ▪ Winnipeg ▪ September 20 - 23 ▪ 2009

Table 2: Comparison of Compost and Sludge on All Parameters Parameter

Unit

Aggregate Organic Constituents Organic Matter % weight Water % Solids % Oil (dry wt.) % Oil (wet wt.) % Classification Nitrogen (TKN) % Metals Mercury mg/kg Aluminum mg/kg Antimony mg/kg Arsenic mg/kg Barium mg/kg Beryllium mg/kg Bismuth mg/kg Cadmium mg/kg Chromium mg/kg Calcium mg/kg Cobalt mg/kg Copper mg/kg Iron mg/kg Lead mg/kg Magnesium mg/kg Manganese mg/kg Molybdenum mg/kg Nickel mg/kg Phosphorus mg/kg Selenium mg/kg Silicon mg/kg Silver mg/kg Strontium mg/kg Thallium mg/kg Tin mg/kg Titanium mg/kg Vanadium mg/kg Zinc mg/kg

Compost (2008)

Sludge (2006)

10.8 32.1 67.4 0.68 0.46

NT 80.2 17.6 11 2.16

0.35

1.08

0.12 6190 3.1 5.1 69 0.2 3.3 1.11 27.7 17700 5.1 283 18800 87.9 3400 282 4 19 1620 0.6 680 1.4 64 <0.05 6 213 15.5 357

0.08 NT 0.4 0.4 24 0.2 NT 0.17 2.7 NT 0.2 170 NT 3.9 NT NT 2 2.2 1420 0.9 NT 1 NT 0.1 2 NT 1 200 WCW iqaluit paper KJohnson CMcCracken 090630 Page 6 of 11

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WCW Conference & Trade Show ▪ Winnipeg ▪ September 20 - 23 ▪ 2009

Parameter

Unit

Microbiological Analysis Total Coliforms MPN/g Fecal Coliforms MPN/g Escherichia coli MPN/g Physical and Aggregate Properties Solids (wet wt.) / Total Solids % Soil Acidity pH Water Soluble Parameters BOD (extractable) mg/kg *NT: Not Tested

Compost (2008)

Sludge (2006)

<3 <3

>1,100,000 >1,100,000 1,100,000

55.7

19.5

7.4

5.6

3400

39500

DISCUSSION Microbiological Content The composting process is reducing the number of total and fecal coliforms to a great extent. As shown in Table 3, the Most Probable Number of both total and fecal coliforms is very high in Iqaluit's raw sewage sludge; lower in a sample of sludge that has undergone a freeze-thaw dewatering cycle; and very low in the composting material. Both the 2008 and 2006 sample results were used to generate the averages in Table 3.

Table 3: Total and Fecal Coliforms in Iqaluit Sludge and Compost Units

Average Raw Sludge

Dewatered Sludge

Average Compost

Total Coliforms

MPN/ g

> 852,500

23,000

18

Fecal Coliforms

MPN/ g

> 852,500

23,000

6

The US Environmental Protection Agency (US EPA) classifies sewage sludge as either Class A or Class B with respect to pathogen content. Either of these classes of treated sludge can be land applied. Compost is considered Class B if the temperature of the compost is raised to 40˚C or higher for five (5) days or longer, and the temperature exceeds 55˚C for at least four (4) hours during this period. The operating temperature of Iqaluit's compost piles during the summer is unknown.

WCW iqaluit paper KJohnson CMcCracken 090630 Page 7 of 11

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WCW Conference & Trade Show ▪ Winnipeg ▪ September 20 - 23 ▪ 2009

Iqaluit’s treated sludge (compost) is either Class A or Class B with respect to pathogens.

One of the alternative ways for a treated sludge to be classified as Class B is if the average fecal coli form count of seven samples is less than 2,000,000 Most Probable Number per gram of total solids (dry weight basis). Iqaluit’s compost is well below this limit for fecal coliforms, so the compost is at least Class B. There are also several alternatives for a treated sludge to classify as Class A, such as having low test counts for certain pathogens.

This has not been examined in detail for Iqaluit’s compost.

Solids Content The freeze-thaw dewatering process, combined with the composting treatment stage, appears to be effective at increasing the solids content of the sludge material. Raw sewage sludge from Iqaluit's WWTP is about 20% solids. As noted in the April 2006 letter report, this is higher than typical for primary sludge which is generally about 6% solids. After the sludge undergoes freeze-thaw dewatering and is mixed with dry wood chip material, the average solids content of the composting material is 58%.

One of the October 2008 sludge samples appears to have advanced in the freeze-thaw dewatering cycle, since the solids content is 44.8%, while four other sludge samples have solids contents of 18, 19.5, 19.6 and 20.9% respectively. This could indicate that the freeze-thaw process is successfully dewatering the sludge. However, no firm conclusions can be made about the effectiveness of the freeze-thaw process due to the limited number of samples.

Figure 3: Solids Content

70.0

60.0

Solids Content (%)

50.0

40.0

30.0

20.0

10.0

0.0

Average of 4 Sludge Samples

Dewatered Sludge

Average of 3 Compost Samples

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WCW Conference & Trade Show ▪ Winnipeg ▪ September 20 - 23 ▪ 2009

Metals Content It was observed that the Iqaluit March 2006 sludge sample had low concentrations for several key metals. The following charts compare the metals concentrations in Iqaluit sludge and compost. The metals concentrations measured in the October 2008 compost sample were somewhat higher than concentrations in the March 2006 raw sludge sample.

A rational explanation for this increase may be the source of the wood waste, which is shredded wood products and contains metal associated with nails and fixtures.

Figure 4: Metals in Sewage Sludge Sludge Sample, March 2006

Compost Sample, October 2008 400

30

350

25 300 250 mg/kg

mg/kg

20 15

200 150

10

100 50

5

c Zi n

Le ad

n Ti

l

iu m Se le n

N ic ke

m en u ol yb d

M

M

er c

ur y

al t C ob

om iu m C hr

c

m iu m C ad

se ni Ar

Co pp er

0

0

The metals shown above have an impact on how a treated sludge (biosolid) may be used or disposed of. Except for tin, these twelve (12) metals are considered "of principle concern" in biosolids used for land application by the Ontario Ministry of Environment (1996). Ten (10) of them are regulated by the US Environmental Protection Agency (EPA) for sewage sludge to be used in land application.

USEPA pollutant limits for sewage sludge are shown in Table 4. Treated sludge must be below the Ceiling Concentration limits for any land application. For application on agricultural land, forest, a public contact site, or a reclamation site, the sludge must meet a more stringent Monthly Average Concentration, or else the application of sludge must be limited by a maximum cumulative pollutant loading rate in kilograms per hectare.

WCW iqaluit paper KJohnson CMcCracken 090630 Page 9 of 11

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Table 4: US EPA Pollutant Limits for Land Applied Sewage Sludge

Land Application2

Surface Disposal3

Pollutant

Units

Ceiling Concentration

Monthly Average Concentration

Maximum Concentration

Arsenic

mg/kg

75

41

73

Cadmium

mg/kg

85

39

Chromium

mg/kg

Mercury

mg/kg

57

Molybdenum

mg/kg

75

Nickel

mg/kg

420

420

Selenium

mg/kg

100

100

Copper

mg/kg

4300

1500

Lead

mg/kg

840

300

Zinc

mg/kg

7500

2800

600 17

420

Iqaluit’s sludge (treated and untreated) is well within the US EPA limits as shown in Table 4. Therefore, based on trace heavy metals content, the compost is suitable for land application.

CONCLUSIONS Based on the sampling to date, the freeze-thaw dewatering and composting processes are effectively treating Iqaluit’s sewage sludge. Compost samples showed a dramatic reduction in total and fecal coliforms compared to the raw sludge samples. As well, the solids content of compost samples and one partially treated sludge sample was much higher than that of the raw sewage sludge. The processes do not appear to have any significant impact on some contaminants, including metals, but this result is expected.

It is worth noting that the metals concentrations in Iqaluit's sewage sludge and compost are below the US EPA limits on sludge for surface disposal and land application. Iqaluit's treated compost has very low pathogen counts, and likely could be classified as Class B sewage sludge or even Class A. This means that the treated compost is suitable for land disposal and some types of land application.

2

Land applications are defined as the spreading of sewage sludge onto land to condition soil or fertilize vegetation.

3 Surface disposal is defined as placing sewage sludge on an area of land for final disposal.

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RECOMMENDATIONS It is recommended that the City of Iqaluit continue to use freeze-thaw dewatering and composting to treat the sludge from its Wastewater Treatment Plant. These processes are successfully reducing the microbiological content and increasing the solids content of the sewage sludge. In addition, the technology is cost-effective and requires a modest amount of work to operate and maintain, particularly when compared to other technologies.

Based on a cursory examination of US EPA sewage sludge use and disposal regulations, Iqaluit’s treated sewage sludge (compost) is suitable for use as a cover material at the landfill. With a potential savings of $40 to $60 per cubic metre by using composed sewage sludge instead of conventional granular landfill cover, Iqaluit’s compost may be considered black gold.

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Northern Systems Water Reuse & Recycling

Dawson City

digs deep for sewage treatment

By Ken Johnson, AECOM

There are strange things done in the midnight sun by the engineers who design for the cold, The arctic trails have their secret tails that will make your bid dollars explode, The arctic nights have seen queer sights, but the queerest they ever did see, Was the night on a nook of a Klondike brook there was a deep hole dug to treat Dawson “pee.”

(With apologies to Robert Service)

(Cartoon by Wyatt Tremblay was originally seen in the Yukon News. Used with permission.)

Sewage treatment in Dawson City, Yukon Territory has had an interesting history, and for the past 30 years a rather controversial one. Prior to 1979, sewage from Dawson discharged directly into the Yukon River, through a series of over a dozen independent wood stave pipe outfalls, without any treatment.

Sewage treatment entered the picture in 1979 with the completion of a “screening plant” that provided something better than preliminary treatment (the removal of two-by-fours and bicycles), but not quite primary treatment. This was a logical improvement to the sewage infrastructure serving Dawson City, and was followed by the replacement of much of the wood stave piping with insulated plastic (HDPE) piping.

From an environmental impact perspective, this improvement was not considered to be a significant improvement, but from an aesthetic perspective, the removal of the “floatable” component of the sewage was very significant.

As well, the sewage discharge configuration was changed from the many shore discharges to a single submerged discharge near the centre of the Yukon River. The relocation and opportunity for increased dispersion of the sewage, through the current mixing regime, provided a significant public health improvement to the shore discharges. Dawson was apparently left alone until 1983, when they were first directed, as part of their water licence compliance, that they would have to clean up their act if toxicity could be established – and 26 years later this controversy still rages on.

Limited arguments were made that preliminary treatment did not go far enough in 75

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Northern Systems

1979 to improve the effluent discharge into the Yukon. However, given the nature of the overall improvements at the time in Dawson’s water and sewer system (which included the complete replacement of all of the piped water and sewer and the elimination of the raw sewage discharges into the Yukon River) the improvements at the time were considered to be an appropriate increment.

Improvements to the Dawson City wastewater treatment system have been at various stages of planning over the past two decades, and the work advanced to the detailed design of a SBR system in 2003. However, the construction of this system was never tendered because the estimated operation and maintenance costs exceeded $600,000 per year – this was unsustainable for a community with a permanent population of less than 2,000.

On the regulatory front, the pressure was maintained, and it reached a climax with a police raid on the Dawson City municipal offices in 2003. Dawson was subsequently charged under the Fisheries Act for the discharge of a deleterious substance, and court order was placed on the community. A judge has been monitoring the progress of the work ever since.

From an engineering perspective, the project switched gears, and aerated lagoon technology entered the picture. Aerated lagoon technology has been operating successfully in Alaska and in the northern reaches of the provinces, so the process was a logical alternative to mechanical treatment. The main obstacle was the level land on which to build the lagoon.

At first glance, Dawson appears to have a relative abundance of land, in spite of the mountainous terrain. However, with placer mining claims and aboriginal land claims, the abundant land is reduced to mere morsels.

Ultimately, the lagoon option failed to advance when a land-use referendum vetoed the chosen site in 2008. The referendum put an end to the government’s proposed site for an aerated surface lagoon at the junction of the Dome Road and the Klondike Highway.

Instead of commissioning a consultant to complete yet another design, and then tendering it for construction, the Yukon Government charted a new course by issuing a design/build

request for proposals, where the solution and risk associated with the solution were put to the private sector. The outcome of the design/ build process was the selection of Corix Water Systems as a proponent for an innovative solution for Dawson City.

The key to the system proposed by Corix is the patented Vertreat process used by Noram Engineering. Vertreat is a technology that employs a “deep shaft” as the primary treatment vessel instead of the more common aerated basin at the ground surface. A similar system has been operating in Homer, Alaska for almost 20 years (see photo of Homer’s UV system above).

The advantages to the deep shaft version of an aeration basin were presented by Corix-Noram at a public information session in September in Dawson City. The system was described by Corix-Noram as being a good fit for an area where there are concerns about space limitations, extreme low temperatures, fluctuating sewage loads, seismic activity, and proximity to residential areas. Corix-Noram also claims that the Vertreat system uses about half the power of a conventional mechanical sewage treatment system.

In the operation of the Vertreat process, the influent is directed to a vertical 85 metre aeration shaft, where air is injected under high pressure, and supersaturates the influent with oxygen. From the aeration shaft the influent flows into a flotation clarifier, where the sewage sludge is separated before UV disinfection and discharge.

With the construction of the deep shaft, and the record setting capital cost of $25 million, Dawson City and the Yukon Government are “digging deep” literally and financially for the new wastewater treatment facility. In spite of the continuing controversy about wastewater treatment in Dawson City, Yukoners maintain their sense of humour. This was very clearly demonstrated by Wyatt Tremblay’s April cartoon in the Yukon News.

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Winter 2009 | Western Canada Water | 45

Diavik Diamond Mine Water Management Plan Ken Johnson Published in the Journal of the Northern Territories Water and Waste Association. 2009.

Dell Communications Inc. Ken Johnson - Editor Introduction The Lac de Gras watershed is a pristine region feeding into the Coppermine River which travels 850 kilimmetres to the Arctic Ocean at the community of Kugluktuk. This river is a world class Arctic Char fishery and a traditional harvesting are for the Inuit of the Kugluktuk Region.

Lac de Gras is 60 kilometres long, with an average width of 16 kilometres and 740 kilometres of shoreline. The average depth of Lac de Gras is 12 metres, with a maximum depth of 56 metres. As an arctic lake it is cold year round, with temperatures ranging from 0 to 4 C in the winter and 4 to 21 C in the summer. Lac de Gras freezes in October and spring breakup is in July and the average ice thickness is 1.5 metres. Typical of arctic lakes, aquatic productivity in the lake is low because of the relatively low concentrations of nutrient, low light level during winter months with the ice cover and low water temperatures.

The Diavik diamond mine is built on a large island in Lac de Gras, 300 kilometres northeast of Yellowknife, and has been operating since 2003. To prevent runoff from the site from entering the lake, the mine was constructed with an extensive water collection and treatment system. Through a system of sumps, piping, storage ponds and reservoirs, the mine collects run off water, which can be reused in processing or treated before being released back into Lac de Gras.

Plant and surface operations water management requirements include:  North Inlet Water Treatment Plant (NIWTP) and North Inlet containment and outfall  Surface runoff and seepage pond system;  Potable water, sewage treatment, raw water and fire water;  Recycling and raw water use associated with the Process plant and the Processed Kimberlite Containment facility (PKC).

North Inlet Containment and Water Treatment Plant The North Inlet Water Treatment Plant (NIWTP), North Inlet containment , and the North Inlet outfall have the fundamental objective of treating water to meet compliance requirements prior to discharge to the environment.

Waters directed to the North Inlet originate from:  Pit and underground inflows;  Surface runoff from North Inlet drainage basin;

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ď&#x201A;ˇ ď&#x201A;ˇ

Surface runoff from disturbed areas; and Water transfers from the Clarification Pond.

Water inflows are received at the North Inlet and then pumped to the NIWTP for treatment. The North Inlet has an estimated 2.5 million cubic metres of storage. The North Inlet provides surge storage capacity and allows some solids to settle before water is treated at the NIWTP. The NIWTP was designed to remove fine solids in cold water conditions.

Major system components include coagulant and flocculant preparation equipment, two high capacity clarifiers, and four deep bed sand filters.

The filters and pH-control system have not been required to achieve water license compliance, thus the NIWTP is operated with the clarifiers on a standalone basis. Bypassing the filters in the treatment circuit permits throughput to be increased from 20,000 m3/day to a maximum of 45,000 m3/day. Treated effluent is discharged into Lac de Gras via two submerged outfall and diffusers located 200 m offshore at a depth of 20 m.

Surface Runoff Management Surface runoff historically occurs over a five month period from May to September. Runoff volumes depend on the particular weather conditions, and Diavik selected 1 in 100 year return conditions for sizing surface runoff collection systems.

The surface runoff collection system consists of a network of ponds that collect runoff from the North Country Rock Pile, South Plant Site (Ponds 10, 11 and 12) and the PKC dam toes.

Pipelines are permanently installed to permit transfer of waters from the collection ponds to the PKC facility.

Collection ponds are designed to hold, without discharge to the environment, 100% of a 1 in 100 year return period freshet occurring over an 8 day period.

As pond watershed surface areas will change over the life of the mine, the maximum watershed area was considered during pond design.

Aircraft fueling and de-icing is performed on the airport apron, which is sloped toward the North Inlet. Fuel or de-icing spills would be directed to the North Inlet.

Pond 3, located west of the North Country Rock Pile, collects seepage from the North Country Rock Pile and can be used as temporary storage for mine water. If water quality meets discharge criteria, it may be discharged to Lac de Gras; otherwise it is transferred to the North Inlet or the PKC facility. The pond water collection system was designed to transfer pond waters to the PKC facility. If collected runoff waters meet the water license quality limits, they may be discharged directly to Lac de Gras.

Potable Water Supply and Sewage Treatment The potable water system consists of deep bed multi-media filters, polishing filters, and chlorine dosing. The raw water is supplied from the overall raw water supply system. The plant is sized to accommodate 800 persons.

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Raw and fire water are pumped from Lac de Gras through distribution systems servicing the south plant site. The raw water system has a design capacity of 250 m3/hour, plus standby capacity. Flow demands include the process and recovery plant; a mobile equipment wash bay; and the potable water. The fire water system has a design capacity of 454 m3/hour plus standby capacity.

The South Sewage Treatment Plant (SSTP) services the south plant site including operating facilities, the construction camp, and permanent accommodations. Sewage treatment capacity is designed to accommodate 800 persons at a design flow rate of 300 litres/person/day, for a total of 320 m3/day. The SSTP is an activated sludge system with tertiary filtration. Treated effluent is disinfected with chlorine. The WWTP discharge into the PKC system.

Processed Kimberlite Containment (PKC) Facility Key objectives of the PKC facility and Process water management system to provide storage of processed kimberlite (PK); act as an equalization reservoir for supernatant water and runoff water for process plant re-use; and provide recycled water to the Process Plant.

The Process and Recovery Plants are both the primary consumers and suppliers of water to the PKC facility. The plants consume reclaim water and raw water for ore processing, and generate coarse (1 mm to 6 mm) and fine (less than1 mm) PK. Coarse PK is transported by truck to the coarse PKC storage area, and fine PK is transported as slurry via an insulated pipeline to the PKC facility.

The Process and Recovery Plants are designed to maximize reclaim water recovered from the PKC pond to minimize raw water use. Reclaim water is used for essentially all process services in the Process Plant.

Conclusions The Diavik diamond mine is a unique world class operation, with world class water management systems. The water management demands on Diavik and the other diamond mines in the Canadian north have been high, but given the pristine nature of the environment, these demands were warranted.

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Figure 1. The Diavik diamond mine on Lac de Gras is the headwaters of the Coppermine River which flows past historic Bloody Falls on its way to the Arctic Ocean.

Figure 2. Diavik is located on an island within Lac de Gras, and mines from dyked Kimberlite deposits within the lake.

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Figure 3. The Diavik water management system schematic shows the extensive collection, reuse and treatment processes.

Figure 4. The Diavik water management system uses sumps, piping, storage ponds and reservoirs.

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Water and Sewer Challenges in Kashechewan, Ontario Ken Johnson Published in the Journal of the Northern Territories Water and Waste Association. 2009.

Dell Communications Inc. Ken Johnson - Editor Background Kashechewan is a Cree First Nations community of about 1,900 people, 10 kilometres upstream from James Bay on the Albany River in Northern Ontario. The community is located at 81 38 degrees west longitude and 52 17 degrees north latitude. The closest urban centre to the isolated town is Timmins, Ont., 400 kilometres to the south. The community lies on the flood plain of the Albany and many of its buildings are susceptible to flooding in the springtime.

The climate of the Hudson's Bay Lowlands is of long cold winters and short warm summers.

Permanent ice may appear between late Novembers and will provide cover until the end of April or early May. The terrain and vegetation are sub-arctic with a predominance of open cover of stunned black spruce and tamarack in the swamps and peat land. The banks of the Albany River, river in lands and tributary streams however, are forested with heavy cover of white spruce.

A new water treatment plant was built for the community in 1995 to replace an existing plant that was at the end of its design life. October 2005, high E. coli levels were found in the reserve's drinking water, and a major evacuation of the community occurred with about 800 community's residents airlifted to the northern Ontario communities.

Water Supply and Treatment The Kashechewan water treatment plant uses a surface source from Red Willow Creek. The creek feeds into the Albany River, which ultimately flows into James Bay. The water treatment plant is located at the mouth of Red Willow Creek. It is a conventional treatment plant with chemically assisted filtration and disinfection processes and is capable of producing approximately 1,400 cubic metres of treated water per day.

The raw water intake for the plant is a 200 mm diameter pipe that extends approximately 90 m into the creek. The intake crib is located in the vicinity of where the creek feeds into the Albany River at a depth of 4.5 m.

Water from the Red Willow Creek flows through the intake, and into a raw water intake well located on shore. From there, the raw water passes through a coarse screen to remove large debris or fish entering into the plant's low lift well. The water treatment plant intake in Red Willow Creek was positioned so that potential contamination from overflow of raw sewage from the sewage collection system into the Albany River would be minimized. Tides from James Bay do influence the flow of the Albany river, and in fact may cause some reverse flow in the river under certain circumstances.

83

From the low lift well, the water is pumped via two low lift pumps to the clarification treatment process in the plant. Coagulant chemical is added in the low lift well pump discharge pipe to aid in the settling of particulate matter in the raw water. Clarification water is pumped from the low lift well to the plant's single clarifier. A temporary polymer feed system is set up on the clarifier. Within the clarifier, the larger, heavier, particulate matter is allowed to settle to the bottom. The clarified effluent then flows into the plant's filtration system. Sludge at the bottom of the clarifier is discharged to the sanitary sewer.

The filtration system at the plant consists of two (2) sand and anthracite media gravity filters.

Water from the clarifier enters into a splitter box and proportionate water enters into each filter by gravity. The filtered water is chlorinated and flows into the plant's clearwell. The clearwell is comprised of two (2) separate cells, each with a volume of approximately 280 cubic metres. Treated water from the clearwell is pumped into the distribution system via five (5) high lift pumps. There is also one (1) fire pump for emergency services.

Sewage Collection and Disposal The Kashechewan First Nation sewage collection system includes gravity sewers, three sewage lift stations and forcemains. The main lift station pumps the sewage across Red Willow Creek to the sewage treatment facility. The main lift station has an overflow to direct raw sewage to the Albany River via the overflow sewer should the lift station fail.

The sewage treatment facility is located immediately north-east of the community, on the north-east side of Red Willow Creek. The community is located on the opposite shore. The facility consists of two individual lagoons. Lagoon 1 was constructed in about 1988, has an estimated working capacity of 83,000 m3. The working capacity of cell 2, constructed in about 2000, is approximately 104,000 m3. The lagoon cells were designed to discharge on a seasonal 7-day discharge basis, including one discharge period in the spring and one in the fall of each year. Treated effluent from the discharge chamber enters a ditch that leads to East Creek. East Creek flows in a north-easterly direction for a distance of approximately 8 km from the sewage lagoons towards James Bay. Concerns with Water and Sewer Infrastructure A comprehensive assessment was completed after the 2005 incident as a means to document the circumstances that lead up to the contamination event, and provide a framework for action to reduce the chances of a similar incident occurring in the future.

The following observations were made regarding the water system at the time of the incident: The water treatment system had inoperative valves, pumps and feed lines, including check valves on the supply piping from the low lift pumps; chemical metering pumps; and completely obstructed chemical feed lines.

84

There were no up-to-date record drawings available on site for either the water treatment plant or water distribution system, and there was no apparent documented procedure for the disinfection of drinking water at the water treatment plant.

An insecure bypass had been installed so that raw water could be directed around the clarifier to the filters and there were a number of potential cross-connections between treated and untreated process wastewater There was limited process instrumentation for monitoring the operation of the water treatment plant.

The following observations were made regarding the sewage system at the time of the incident: The overflow sewer was located adjacent to the shoreline of the Albany River, upstream of the surface drinking water supply intake within the Red Willow Creek.

Tidal influences experienced in the area could potentially transport contamination along the shoreline of the Albany River and near the drinking water intake.

There was no dedicated standby power supply for the sewage collection system. This circumstance increases the potential for raw sewage to overflow to the Albany River during an extended power supply outage.

Two of the three sewage lift stations were non-operational. Under these conditions, if the remaining sewage lift station failed, there was the potential of an overflow of sewage to the Albany River.

The overflow sewer and associated backflow prevention device were broken; this could permit water to enter the sewage collection system, resulting in flooding of the community during high water levels in the Albany River.

Conclusions The lessons learned from Kashechewan are not unique, in fact the elements of the Kashechewan experience have been evident in many of the communities across the north at some point in time over the past 20 years. What is unique about Kashechewan is that a series of circumstances lead to an outcome and an action that received national attention.

The Kashechewan story is far from over as the Federal government considers what long term action is needed to reduce the risk of an incident like this in the future, not only in Kashechewan, but other remote northern communities.

85

Figure 1. Community of Kashechewan and adjacent infrastructure

86

Figure 2. Kashechewan water supply and sewage treatment systems.

87

Figure 3. Schematic of Kashechewan water treatment processes.

Figure 4. Schematic of kashechewan sewage treatment system.

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WCW Conference & Trade Show ▪ Winnipeg ▪ September 20 - 23 ▪ 2009

Infrastructure Serving Dawson City, Yukon – The New Klondike Gold Ken Johnson ABSTRACT Dawson City’s water and sewer services are provided by a buried, insulated high density polyethylene pipe (HDPE) utility system which was completed around 1980. The water and sewer infrastructure is reasonably complex in both its construction and operation. Beyond the piping systems that are associated with the infrastructure, there are 12 facilities that are an integral part of the infrastructure. The facilities handle approximately 850,000 cubic metres (190 million Imperial gallons) each of water and sewage in a year.

Freeze protection for the water system is needed during the winter; the water in the pipes cools as it flows through the distribution piping, therefore additional heat is required to prevent the water in the pipes from freezing. The water is also re-circulated by pumping to confirm the water temperature in the pipe, and provide additional freeze protection.

Subsoil conditions in Dawson City typically consist of organic silts, and silts, and this layer has an ice content varying from zero to greater than 50 percent excess ice content. This area is in the widespread discontinuous permafrost zone, with mean ground temperatures in the range of -1.5 C, which is considered to be “warm” permafrost. Problems with respect to water and sewer systems in these soil conditions have caused ground subsidence due to thaw of the ice rich permafrost, seasonal frost heave of buried foundations and utility pipes, or groundwater conditions.

The soil conditions in Dawson City have required the development of unique and expensive water and sewer piping materials and installation techniques. The installation of the pipe requires consideration of the permafrost conditions to ensure that the area around the excavation is not significantly disturbed, particularly in areas where the permafrost has a lot of ice lensing.

Dawson City continues to incrementally address the challenges of operating and maintaining a water and sewer facilities in the heart of Klondike. Bleeder reduction has been a priority over the past several years and water metering has been implemented to reduce water down in the range of 500 litres/capital/day from winter extremes of 1500 litres/capita/day. A comprehensive water and sewer facility assessment was completed in 2006, which has provided Dawson with the framework for system improvements over the next 20 years. The most significant infrastructure improvement in the next several years will be an upgrade in the sewage treatment system, which will cost approximately $25 million.

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Introduction Dawson City owns and operates water, sewage and drainage infrastructure which serves the residents, and businesses of the community. This infrastructure is reasonably complex and requires a dedicated staff of 5 individuals to operate and maintain. A lot has changed for the infrastructure in Dawson over the past 4 decades; as recently as the mid 1970’s, the community was still using wood stave pipe for the delivery of potable water (See Figure 1).

Figure 1. Installation of wood stave pipe in Dawson City (circa 1975) Beyond the piping systems that are associated with the infrastructure, there are 12 facilities that are an integral part of the infrastructure (See Figures 2 and 3). These facilities include:       

Water well vaults (two) Well supply control building Backup well supply and building Water treatment and distribution pump house Valve chamber building Sewage lift stations (5) Sewage treatment plant

The facilities handle approximately 850,000 cubic metres (190 million Imperial gallons) each of water and sewage in a year (2005 estimate).

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Figure 2. Dawson City water infrastructure The age of these facilities ranges from approximately 15 years to almost 50 years, with the majority of the facilities being almost 30 years old (1979 construction). From a facility “lifespan” perspective, facilities that are over 25 years old are generally considered to be approaching the end of their service life. This is not to say that the facility needs to be replaced, but rather that the facility needs to be assessed, and major improvements may be required.

Description of Facilities Water System Dawson City’s water system facilities consist of the water source, the water storage, and the water treatment and distribution (See Figure 2).

The water source consists of a series of four wells located along the river bank, beside Front Street, at the junction of the Klondike and Yukon Rivers. The wells were drilled to depths of approximately 23 metres (80 feet), and each well is equipped with a 22 kilowatt (30 horsepower) submersible pump. One original well was installed in 1959 on Front St. and Craig St., near the power plant, and three additional wells were installed in 1991 on Front

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St. and Church St. to provide additional capacity. The newer wells are situated in concrete access vaults with an adjacent well control building. The original well is situated in a wooden building, and is generally used only as an emergency back up supply.

The water storage consists of two insulated steel reservoirs located on 5th Ave and Dugas St., beside the water treatment and distribution building. The two reservoirs have a combined storage of approximate 1300 cubic metres (290,000 Imperial gallons), which provides storage for drinking water supply and fire protection.

The water treatment and distribution consists of a building which contains various chemical, heating, pumping, electrical and piping systems for water treatment, freeze protection for the system, and water distribution. The water treatment consists of controlled chlorine gas injection into the water prior to distribution into the buried water systems; the chlorine provides disinfection to the water from the wells and a “residual” level of disinfection as the water is distributed throughout the community.

Freeze protection for the water system is needed during the winter; the water in the pipes cools as it flows through the distribution piping, therefore additional heat is required to prevent the water in the pipes from freezing. Heat from several oil fired boilers is injected into the water to maintain the water supply several degrees above zero. The water is also re-circulated by pumping to confirm the water temperature in the pipe, and provide additional freeze protection.

The pumping of water into the distribution piping systems utilizes 100 kilowatts (130 horsepower) of electric pumping capacity.

An additional 100 kilowatts (130 horsepower) of diesel pumping capacity is available to provide fire flow to the distribution system.

The water distribution system itself consists of 16 kilometres (10 miles) of insulated, buried water main, which has sizes between 150 millimetres and 250 millimetres (6 inches and 10 inches). The distribution system includes approximately 700 service connections to buildings and 85 on-line fire hydrants (See Figure 3). The system also includes a valve chamber building for controlling the flow of water.

Figure 3. On-line hydrant in Dawson City Page 4 of 7

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Sewage System Dawson City’s sewage system facilities consist of the five lift stations, and the sewage treatment plant (See Figure 4).

The sewage collection system itself consists of 16 kilometres (10 miles) of insulated, buried sanitary sewer, which has sizes between 150 millimetres and 250 millimetres (6 inches and 10 inches), and approximately 3.5 kilometres (2 miles) of buried force main from the lift stations.

The collection system includes approximately 700 service connections to buildings.

Figure 4. Dawson City sewage infrastructure.

The sewage lift stations generally consist of submersible pumping systems in wet wells, with control buildings either on top of or adjacent to the wet wells. Four of the lift stations may be considered “small” facilities, and the remaining facility may be considered a medium sized facility. Four of the lifts stations collect sewage from the developments along the Klondike Highway up to the Callison development. The force main from these lift stations discharges into a manhole at the top of Craig St. The sewage treatment facility consists of a primary screening operation using two 0.75 millimetre mesh rotostrainers controls, and backup power. The building has three levels; the upper level is at the ground elevation and provides space for the heating and ventilation equipment. The middle level provides space for the screening operation, and an adjacent operating area. The lower level provides space for the inlet and outlet pumps and piping.

The sewage discharges into the Yukon River, mid-channel 200 metres (650 feet) west of dyke for flood protection.

Concerns with Facilities With the age of these facilities ranging from approximately 15 years to almost 50 years, and the majority of the facilities being almost 30 years old, there is a concern that the facilities

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may be at the end of their service life. This concern is supported by the corrosion that may be observed in many of the facilities.

The facility operating staffs have been undertaking incremental measures to replace badly corroded components with new stainless steel components. This has been undertaken on a limited basis with the available human and financial resources.

The age of the facilities also suggests that improvements may be necessary so that the facilities are operating within the current applicable building and related codes. Of particular code related importance in the current operation water and sewage facilities is the “confined space” ventilation, which applies to chlorination of drinking water and processing of sewage (pumping, and screening); odour control is also another issue.

Challenges of Dawson City Water and Sewage System Subsoil conditions in Dawson City typically consist of a surface layer of common road fill 0.6 to 0.9 metres in thickness, underlain by organics, organic silts, and silts to a depth of 3 to 5 metres. This layer of silt and organic silt has an ice content varying from zero to greater than 50 percent excess ice content. Beneath this layer of organic silt, a layer of alluvial gravels has been deposited by the Yukon River; these gravels are relatively dense and thaw stable.

This area is in the widespread discontinuous permafrost zone, with mean ground temperatures in the range of -1.5 C, which is considered to be “warm” permafrost. Since the permafrost temperature is just below freezing, the permafrost may thaw or degrade very easily from disturbances such as the installation of underground utilities. Problems with respect to water and sewer systems in these soil conditions have caused ground subsidence due to thaw of the ice rich permafrost, seasonal frost heave of buried foundations and utility pipes, or groundwater conditions. In a two year period, in the mid 1980’s over 225 metres of polyethylene sewer pipe failed by ovalling or collapsing.

The problems due to frost action in the soils were compounded in the vicinity of hydrants, vertical risers and service connections because a vertical restraint is imposed on the piping system. At service connection locations, there were numerous examples of service risers causing a local collapse of the main because of the vertical load on the horizontal sewer main. Adjacent to hydrants and valves, pipe failures occurred at fusion weld joints because of bending or torque along the connecting pipe.

The unique soil conditions in Dawson City have required the development of unique water and sewer piping materials and installation techniques. Several studies in the late 1980’s compared pipe and bedding configurations, and developed the corrugated cover on insulated HDPE piping that is the pipe standard for Dawson City today (See Figure 5). The installation of the pipe requires consideration of the permafrost conditions to ensure that the area around Page 6 of 7

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the excavation is not significantly disturbed, particularly in areas where the permafrost has a lot of ice lensing.

Figure 5. Insulated piping in Dawson City with corrugated metal cover.

Future Water and Sewer Improvements Dawson City continues to incrementally address the challenges of operating and maintaining a water and sewer facilities in the heart of Klondike. Bleeder reduction has been a priority over the past several years and water metering has been implemented to reduce water down in the range of 500 litres/capital/day from winter extremes of 1500 litres/capital/day. A comprehensive water and sewer facility assessment was completed in 2006, which has provided Dawson with the framework for system improvements over the next 20 years.

Dawson is putting considerable effort into the operation and maintenance of its ground water supply system to ascertain if the wells are under the direct influence of surface water, and to characterize the ground water in regard to aggressive activity in metal pipes.

The most significant initiative in recent years has been the upgrading of the preliminary treatment system with a mechanical sewage treatment system. The process selection for the mechanical system applied a design/build competition, and the recommended process is a deep shaft activated sludge configuration. This process is somewhat unique; however a similar process has been operating successfully in Homer, Alaska for the past 16 years. The capital cost for the deep shaft technology will be approximately $25 million, with an estimated annual operation and maintenance cost of less than $300,000. With the high cost of infrastructure in Dawson City, the new gold in the Klondike may be associated with water and sewer not the nuggets of yellow metal.

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ADVANCING WASTEWATER TREATMENT IN INUIT REGIONS OF CANADA Ken Johnson Earth Tech Canada Abstract The Inuit regions of Canada include the Inuvialuit region of the Northwest Territories, the Nunavut Territory, the Nunavik region of Quebec, and the Nunatsiavut region of Newfoundland and Labrador, and comprise a land area totaling about 40% of Canada's total land area with a population of approximately 41,000 individuals living in one of 53 communities. The regions are represented on a collective basis by the Inuit Tapiriit Kanatami (ITK).

The continuing work the Canadian Council of Ministers of the Environment (CCME) on the Canada-Wide Strategy for Management of Municipal Wastewater Effluent has been largely ignored by the Inuit regions, not for a lack of potential interest, but for an absence consultation by the Federal Government. The ITK were finally brought into the fold of the consultation process in the fall of 2007 in advance of the stakeholder deadline of January 31, 2008. A flurry of activity occurred within the ITK and from various technical resources retained by the ITK in order to respond to this deadline with a meaningful and comprehensive position for the Inuit regions of Canada. The fundamental concern expressed by the ITK is that the strategy has a geographic and cultural bias that is inherent to the process of advancing from principles to practice in the proposed "roll out" of the strategy.

A position paper was prepared and submitted by the ITK on January 31, 2008 which identified many deficiencies in the strategy as it applies the Inuit regions and the north in general, and recommended realistic timelines, funding for research into the science, applied science (engineering) and social science of arctic wastewater treatment. The position paper also recommended specific actions and financial needs for wastewater characterization, incremental improvements to wastewater treatment processes, research into "best appropriate technology", establishment of a regulatory framework, education and training, public education, and community consultation. With this position paper, and the extensive supporting documentation, it is the intent of ITK to influence the Government of Canada in its decision making, so it does not leave a legacy that will impact the well being of the Inuit across Canada for generations to come.

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REGIONS AND COMMUNITIES Inuvialuit Settlement Region The Inuvialuit Settlement Region is located in the northwestern part of the Northwest Territories. The Inuit population is approximately 5,000 living in the mainland communities of Inuvik, Aklavik, Tuktoyaktuk, and Paulatuk and the two island communities of Sachs Harbour (Banks Island) and Holman (Victoria Island). Inuvik is the administrative centre for the region and has a total population of 3,400 of which 1/3 are Inuvialuit. Inuvik is the only Inuit community in Canada that has an all season connecting road to the south; the communities of Tuktoyaktuk and Aklavik have only a seasonal ice road. The communities of Sachs Harbour, Ulukhaktok, and Paulatuk continue to rely solely upon air and marine connections for transportation and supplies.

Nunavut Nunavut has an Inuit population of approximately 23,000 people living in the regions of Qikiqtani (eastern region), Kivalliq (central region), and the Kitikmeot (western region).

The territory's twenty-six communities generally have populations of around 1,000 or less. The regional administrative centres of Cambridge Bay in Kitikmeot, and Rankin Inlet in Kivalliq, have populations of 1,300 and 2,700 respectively. The territorial capital, Iqaluit, is the largest community with a population of over approximately 6,000.

The primary method of transportation between the communities and the south is via air and marine vessels.

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Qikiqtani Region of Nunavut The Qikiqtani region is located at the eastern part of Nunavut and includes Baffin Island, the eastern High Arctic Islands, and the Belcher Islands. The Inuit population of the region is approximately 12,000 living in 13 coastal communities: Iqaluit, Kimmirut, Cape Dorset, Hall Beach, Igloolik, Arctic Bay, Resolute Bay, Pond Inlet, Grise Fiord, Clyde River, Qikitarjuaq, Pangnirtung, and Sanikiluaq.

Kivalliq Region of Nunavut The Kivalliq region lies on the western coast of Hudson Bay and includes Southampton Island. Just over 6,000 Inuit live in seven communities: Rankin Inlet, Repulse Bay, Chesterfield Inlet, Baker Lake, Coral Harbour, Whale Cove and Arviat.

Kitikmeot Region of Nunavut The westernmost region of Nunavut has an Inuit population of 4,000 and includes the Boothia Peninsula and Victoria Island. The communities are Cambridge Bay, Kugluktuk, Umingmaktuuq, Bathurst Inlet, Taloyoak, Gjoa Haven and Kugaaruk.

Nunavik Region The region of Nunavik lies north of the 55th parallel in the province of Quebec. Nearly 10,000 Inuit call Nunavik home and live in 14 communities including: Kangiqsualujjuaq, Tasiujaq, Aupaluk, Kangirsuk, Quaqtaq, Kangirsujuaq, Salluit, Ivujivik, Akulivik, Puvirnituq, Inukjuak, Umiujaq, and Kuujjuarapik. Kuujjuaq is the regional administrative centre with a population of approximately 2,300 residents. With a lack of roads connecting the communities, the primary method of transportation between them and the south is via air and marine vessels.

Nunatsiavut Region Approximately 5,200 Inuit inhabit the five northernmost coastal communities of Labrador and the more southern communities of Happy Valley-Goose Bay, Northwest River, and Mud Lake. The coastal communities are Nain, Hopedale, Postville, Makkovik and Rigolet. Nain, with a population of 1,200, is the administrative centre for the northern coastal region. The primary method of transportation between the communities and the south is via air and marine vessels.

Northern communities and Inuit communities in particular, are unique in their "built environment" (see Figure 2). The communities have no road access (with the exception of three communities of the Inuvialuit region), limited access by water (during the ice

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free season), and year round access by aircraft only. The proximity of the various components of infrastructure creates unique interactions.

The size of the majority of the Inuit communities is "very small" with daily wastewater flows of less than 500 m3/day (Reference: Environment Canada. October, 2007, page 8). The populations vary from the largest community of Iqaluit (population of 6000) in Nunavut, to the smallest communities, of Sachs Harbour, Inuvialuit Region, Grise Fiord, Nunavut Territory, Aupaluk, Nunavik Region each with populations less than 200 people.1 Climate, Geography and Terrain The climate in the communities of each of the four Inuit regions is extremely cold, with the average yearly temperatures less than zero degrees C. The warmest average yearly temperate in the four regions occurs in Nunatsiavut region with a temperature of -3 C in Nain. The mean daily temperatures in July range from 5 to 10 C in the Inuvialuit Settlement Region, 5 to 10 C in Nunavut, 5 to 10 C in Nunavik and in the range of 5 to 15 C in Nunatsiavut.

The extremely cold weather may be described further by the number of frost free days in the communities (see Table 1).

Table 1: Average Yearly Frost Free Days for Select Inuit Communities Region Community Average Yearly Frost Free Days Inuvialuit Sachs Harbour 57 Inuvialuit Inuvik 107 Nunavut Resolute 40 Nunavut Rankin Inlet 102 Nunavik Kuujjuaq 115 Nunatsiavut Nain 126

1

The population of 1000 associated with a "very small" system is defined by the typical waste generation for a piped system (500 L/c/d), not a trucked system which is most commonly used in Inuit communities; based on a per capita waste generation of 90 L/c/d, a "very small" community may have a population of 5500 people.

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The geography of the communities in the Inuit regions generally creates great distances between the individual communities themselves, and between the communities and major centres further south. The traditional activity of the Inuit and the development of permanent settlements have placed all but three of the communities along the mainland or arctic island coasts.

The majority of the terrain in the Inuit regions of Canada is Canadian Shield, with smaller regions of Interior Plains and Arctic Lowlands. The Inuvialuit Settlement Region is primarily interior plains with a small area of Arctic coastal Plain. Nunavut consists of Canadian Shield and Interior Plains and Arctic Lowlands; the Kivalliq and Qikiqtani Regions are Canadian Shield terrain, and the Kitikmeot region is and Arctic Lowlands.

Nunavik and Nunatsiavut are located in the Canadian Shield.

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SOCIO-ECONOMICS Inuvialuit Region The Inuvialuit Region is a government region of the Northwest Territories; the government of the Northwest Territories (GNWT) is the senior government responsible for the delivery of services. Locally elected community councils oversee the administration and delivery of a wide variety of services to the hamlet residents in addition to the services delivered by the GNWT. The main employment in the Inuvialuit region is government related, however significant economic development has been provided by oil and gas activities.

Nunavut The Government of Nunavut has an elected territorial legislature representing 23 electoral districts. The legislative assembly operates as a consensus government; therefore the premier is elected by the members of the legislature.

Qikiqtani Region of Nunavut The economy of the region is based upon renewable resource harvesting including a commercial inshore and offshore fishery, arts and crafts, tourism, and the public and service sectors. The public sector is a major employer in the region.

Kivalliq Region of Nunavut Renewable resource harvesting is a primary economic activity and includes a caribou and arctic char processing plant. Tourism has grown substantially in the region and there is some growing interest in mineral exploration as well. The public sector is a major employer in the region.

Kitikmeot Region of Nunavut As well as renewable resource harvesting such as a commercial char fishery and musk ox harvest, the region has considerable mineral wealth that is in the process of being explored and developed. The public sector is a major employer in the region.

Nunavik Region Renewable resource harvesting, the Xtrata nickel mine, tourism, the public sector, transportation and the service industry are all important elements of the regional economy. Each community has its local administration provided by municipal councils

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as established by the Northern Village Corporation. Each Northern Village is part of the Kativik Regional Authority that oversees the administration of the region. The Kativik Regional Government is responsible for the delivery and coordination of municipal infrastructures and services, manpower and training, environmental issues and the coordination of economic policy.

Nunatsiavut Region Locally elected Inuit community councils oversee functions and the provision of services to the municipalities. Harvesting of land and sea resources continues to be an economic mainstay of the region with government employment, fishing, and the service industry being primary employers. The Voisey's Bay nickel deposit has greatly increased the economic activity of the region.

EXISTING WASTEWATER TECHNOLOGY, PERFORMANCE, COST AND OPERATIONS Only three of the 53 Inuit communities, namely Rankin Inlet, Pangnirtung, and Iqaluit, use mechanical sewage systems. The system in Rankin Inlet is preliminary treatment to remove large solids by screening. The system in Pangnirtung is secondary treatment using a rotating biological contactor. The system in Iqaluit has preliminary and primary treatment for the removal of solids by screening. Although designs for secondary treatment systems have been completed in Rankin Inlet and Iqaluit, construction of the advanced systems has not yet been authorized. All of these mechanical systems have significant operating challenges.

Historically, all of the mechanical systems used in Inuit communities have failed at one point or another and communities have fallen back on the use of the simpler technologies of wastewater detention or retention (lagoon systems).

Most of the remaining communities use lagoon systems which are either detention or retention ponds. Detention ponds provide a continuous discharge, and retention ponds provide a periodic discharge. Overall these systems tend to perform well because of the simple technology, although there are problems with undersized systems, maintenance deficiencies and poor operation practices. The five communities of Nunatsiavut directly discharge sewage into the ocean without any sewage treatment.

It has been reported that lagoons and natural lakes perform reasonably well. The data is limited but indicates a Biochemical Oxygen Demand (BOD) reduction in the range of 87% to 96% (BOD less than 150 mg/L and as low as 11 mg/L), Total Suspended Solids (TSS) reduction in the range of 90% to 93% (TSS less that 80 mg/L and as low as 5 mg/L) and fecal coliform reduction in the range of 2 to 4 logs (fecal coliforms less than

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2x106 and as low as 3x101). The influent sewage is estimated to be 600 mg/L BOD, 725 mg/L SS, and 107 coliforms/100 mL. The capital cost of lagoon systems in the Inuit communities are highly variable depending upon the location, granular materials available, competitiveness, and contractor experience and confidence. A lagoon constructed in Grise Fiord (population less that 200) in 1996 cost approximately $300,000; the current cost of this same lagoon would probably be closer to one million dollars In general terms, lagoon systems are multi-million dollar construction projects.

The operation and maintenance of a lagoon system is also highly variable. In Grise Fiord, the annual cost for water and sewer was approximately $2240 per capita (see Table 2); the sewage portion of this cost was approximately $670 per capita.

Year 2001 2002

Table 2: Grise Fiord, Nunavut Operation and Maintenance costs Water $ Sewer $ Total $ 234,391 100,200 334,591 255,959 109,696 365,655

$2,240 per capita per year in 2002 or 6.4 cents per litre for water and sewer Water use - 5,678,500 litres per year or 95 litres per capita per day From an operation perspective, any sewage treatment system, particularly mechanical sewage treatment systems have significant cultural and language barriers which must be addressed on a daily basis. The biological aspects of sewage treatment process are difficult to explain because Inuit have never heard words like clarifier or biomass.

DISCUSSION A significant number of documents and presentations have been prepared in association with the Canada-Wide Strategy for Management of Municipal Wastewater Effluent, and the proposed implementation strategy by Environment Canada. These documents include: • • • •

Canada-wide Strategy for the Management of Municipal Wastewater Effluents.

September 2007.

Proposed Regulatory Framework for Wastewater. October, 2007.

Review of the State of Knowledge of Municipal Effluent Science and Research: Review of Existing and Emerging Technologies; Review of Wastewater Treatment Best Management Practices. January, 2006.

Affordability of Wastewater Treatment Services in Canada. June, 2006

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The documentation provides a comprehensive basis for advancing the harmonization of sewage effluent standards, but in a context that is grounded in southern Canada, and in a non-Inuit cultural context. Elements in the documentation must be challenged in order the guide the any future implementation of the effluent standards in Inuit regions of Canada.

Canada-wide Strategy for the Management of Municipal Wastewater Effluents.

September, 2007.

• Key Element of the Strategy: sustainable funding strategy; facility size; wastewater facility monitoring. Challenge – given the capital, and operation and maintenance costs associated with sewage treatment in Inuit regions, a realistic and sustainable funding strategy would have to be supported by senior governments; Inuit living in communities such as Grise Fiord cannot afford the current sewage cost of $670 per person per year.

• "due to extreme climatic conditions and remoteness of Canada's arctic, alternative performance standards …will be proposed within 5 years" Challenge – data collection and compilation for sewage systems in Inuit communities has been very limited in the past decades for reasons such as cost, human resources and the simple fact that samples often cannot be transported to laboratories in a timely manner; these same conditions will exist over the next years and into the foreseeable future, therefore it is not realistic to state that the necessary science to support alternative performance standards for Inuit communities may be completed within the next five years.

• "all wastewater facilities are required to monitor their effluent discharge" Challenge – Inuit communities do not have the administrative, financial, and human resources to undertake data collection and compilation for sewage systems; this fact has been demonstrated over the past several decades for reasons such as cost, as well, samples often cannot be transported to laboratories in a timely manner.

• "the term arctic is still under discussion…defining arctic include number of growing degree days, mean annual near surface ground temperature and number of ice-free days" Challenge – climatic conditions are highly variable across the arctic, particularly with the onset of climate change; rather than a climatic base for defining the arctic, a geographic base should be used for defining the arctic, which includes the Inuit regions of Canada.

Proposed Regulatory Framework for Wastewater. October, 2007.

• "authorize maximum effluent discharge levels of 25 (BOD and TSS)" Challenge – Inuit communities cannot consistently meet the effluent discharge levels of 25 mg/L for BOD and TSS with the lagoon technology that is the most appropriate to the various conditions in the Inuit regions.

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•

•

•

"timelines to achieve effluent discharge levels in regulations" Challenge – an extended timeline is not going to change the reality that Inuit communities cannot afford the capital, and operation and maintenance costs of any advanced sewage treatment technology without significant and sustained financial support from senior governments. "threshold acute concentration of ammonia versus pH" Challenge – temperature also influences the toxicity of ammonia and lower temperatures reduce the toxicity of ammonia; the low temperature environment of the arctic should be integral to the toxicity considerations for ammonia. "certain wastewater systems have constraints …. due to the extreme climatic conditions and remoteness of Canada's arctic" Challenge – climate and remoteness are only two of many constraints associated with the Inuit communities of Canada's arctic; the decision making must be made on the basis of science, applied science (engineering) and social science (administrative, financial and human resources).

Review of the State of Knowledge of Municipal Effluent Science and Research: Review of Existing and Emerging Technologies; Review of Wastewater Treatment Best Management Practices. January, 2006.

• "the operating an maintenance costs for mechanical treatment systems in the north are substantially higher… such consideration make these treatment process less acceptable to small/remote and northern communities" Challenge – operating and maintenance costs are more than "substantially higher"; the costs are potentially an order of magnitude higher than the south, and Inuit communities cannot afford these costs.

• "considerations in treatment level required include: habits, attitudes and social patterns of the residents of the community" (USEPA documentation) Challenge – these social science aspects of wastewater treatment are not an integral part of the considerations for the Inuit regions and should be.

• "case studies for small central US municipalities; recommendations include: develop in house training; form partnerships with larger regional cities; implement modest but consistent rate increases" Challenge – these recommendations do not apply to Inuit communities.

• "smaller and rural communities may have difficulty in attracting and employing dedicated wastewater treatment operators" Challenge – Inuit communities do have difficulty in attracting and employing operators particularly resources from outside the community.

• "it may be possible to retain private firms to offer operating and maintenance services" Challenge – private firms are not an option for operating and maintenance services in Inuit communities for the reasons of cost and retaining operators.

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•

"many technical resources are available through technical associations, government agencies and internet portals" Challenge – Inuktitut remains the first language of many residents of the Inuit communities, therefore the technical resources are not available to the communities, and may not be available for many years.

Affordability of Wastewater Treatment Services in Canada. June 2006 • "the average annual wastewater charge per household was calculated to be $185.35" Challenge – the value of $185 does not include any consideration of the costs in the Canadian arctic; the costs in the Canadian arctic are potentially an order of magnitude higher.

• "average annual household wastewater charges in Canada appear to be 'affordable' when compared against median annual household income" Challenge – the costs in the Canadian arctic are potentially an order of magnitude higher; Inuit cannot afford these costs without significant and sustained funding from senior governments.

CONCLUSIONS Inuit communities have limited resources available to them, and the reality of sewage treatment in the Inuit regions of Canada is that most communities can only make incremental improvements to their community sewage treatment infrastructure. Those systems which are technologically simple, and engineered for sufficient capacity tend to perform well.

The majority of communities of the Inuit regions of Canada are "very small", very remote, and very cold; therefore the sewage treatment technology must be appropriate to these conditions and must be applied in the context of these conditions. The knowledge of the appropriateness and context for arctic sewage treatment may only gained through research in science, applied science and social science.

Unless significant resources and commitment are applied the research into all aspects of arctic sewage treatment the Canada-wide Strategy for Management of Municipal Wastewater Effluent will have significant impacts and produce significant hardship on the Inuit regions of Canada. These impacts will be financial (capital cost and operationmaintenance cost), human resource, and administrative.

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RECOMMENDATIONS • • • • •

The Canada-wide Strategy for Management of Municipal Wastewater Effluent must include a geographic definition of the arctic instead of climatic definition, which should include the Inuit regions of Canada.

The Canada-wide Strategy for Management of Municipal Wastewater Effluent must have a realistic timelines, and funding for research into, and implementation of the science of arctic wastewater treatment.

The Canada-wide Strategy for Management of Municipal Wastewater Effluent must have timelines, and funding for research into and the implementation of the applied science (engineering) of arctic wastewater treatment.

The Canada-wide Strategy for Management of Municipal Wastewater Effluent must have a realistic timelines, and funding for research into and the implementation of the social science of arctic wastewater treatment.

The Canada-wide Strategy for Management of Municipal Wastewater Effluent must have sustained funding for implementation of wastewater improvements based upon the science, applied and social science research.

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A BRIEF HISTORY OF THE PAST 60 YEARS OF NORTHERN WATER AND WASTE Ken Johnson Earth Tech Canada ABSTRACT Over the course of the past sixty years water supply and waste treatment in Canada has changed dramatically, however the most dramatic changes have occurred in the northern regions of Canada. Sixty years ago much of northern Canada, particularly the smaller communities, were still based upon a subsistence economy and not a wage economy, therefore the infrastructure for water and sewer was essentially non existent. A select few communities, such as Dawson City, Yukon and Yellowknife, NWT had infrastructure in place as a result of the mining boom in each of these communities.

The water and waste practices in the early days of small northern communities were very simple. Water was brought in by hand, from the nearest water source, "outhouses" were used for sewage waste, grey water was dumped adjacent to the houses, and garbage was burned in individual barrels near each household. One of the most significant infrastructure milestones in decade following World War 2 was the development of the community of Inuvik and its above ground piped water and sewer system, which was initiated by the chronic flooding and limited capacity of the nearby community of Aklavik. In 1957, John Diefenbaker's once-famous "northern vision" policy inspired the nation, and advanced further initiatives in northern infrastructure.

Water and waste infrastructure in northern communities continued to make incremental improvements in the 1960's and 1970's as the subsistence lifestyles continued to decline, and more people moved to permanent settlements. Water and sewer tanks were becoming more common, along with indoor plumbing, but these were still limited, and there remained a significant need for engineered water supply and wastewater disposal systems. One of the most significant policy decisions concerning water supply infrastructure occurred in the mid-1980's with the recognition that intestinal disease could be correlated to water use. As a result, a policy was put in place that water supply infrastructure would be required to deliver a minimum of 90 L/c/d in each individual in a community. This policy initiated a concerted effort to provide indoor plumbing to each household, and phased out the use of honey bags for sewage disposal.

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The turn of the 20th century in the north has brought regulatory demands into the forefront of community infrastructure, for the better and worse of northern communities.

Continuing incremental improvements in water and waste infrastructure as a result of regulatory demands have benefited communities. On the other hand, regulatory scrutiny has placed many communities in positions where they have neither the financial nor human resources to address the regulatory demands.

BEFORE 1948 Northern Canada has remained first and foremost the homeland for aboriginal peoples and a pristine environment. Attachment to the land and dependence on local resources for physical and spiritual sustenance are deeply rooted characteristics of the aboriginal cultural heritage. Each of the aboriginal groups identifies with a traditional territory, shaped by thousands of years of continuous occupation.

The land mass itself is immense, covering almost 45% of Canada's land mass that stretches 4500 kilometres along the 60th parallel and 2800 kilometres north from the 60th parallel to the edge of the Ellesmere Island, which is just 800 kilometres south of the north pole.

Until the 1800's and into the early the 1900's, the economy was based solely on traditional activities of a nomadic lifestyle following an annual cycle set by the weather and the wildlife. This subsistence economy began to shift with the advent of whaling activities in the eastern Arctic, and the expansion of the fur trade into the North, making cash and trade goods important commodities for the aboriginal population. The shift continued with the establishment of permanent communities first by traders, and then missionaries; ultimately government institutions established a presence in the communities.

In the mid 1940's the citizens of Yellowknife and Aklavik installed surface water distribution systems to supply water to their houses during the summer. This was luxury for them, for the rest of the year they had to haul or carry water to their homes, and for rest of the communities of the Northwest Territories even summer only piped water system was a "pipe dream". In most of the communities, the people threw waste water on the ground near their doorway, and discarded toilet water and garbage a distance away to be disposed of by gull, raven and scavenging dogs. In a few larger communities toilet waste and garbage were hauled to isolated places nearby. Such were water, sewage and garbage serving in the Northwest Territories 60 years ago (from the Changing North by Jack Grainge, 1999).

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DAWSON CITY INFRASTRUCTURE One community was the exception to the rule regarding modern water and sewer infrastructure. Dawson City, Yukon was the largest city west of Winnipeg at the turn of the 19th century, and in spite of its extreme isolation had many amenities, including a piped water and sewer system. The engineering and construction resources for this infrastructure may be attributed to the placer mining resources in the community at the time. Dawson was in fact building extraordinary hydraulic projects as the need for water was driven by the placer mining activity.

The date of construction of the first components of the Dawson City water and sewer system is not known precisely, however, it has been recorded that Dawson had a water and sewer system in operation as early as 1904. A description of the system operation in 1911 states that "only three or four houses in Dawson were equipped with year-round running water. To prevent their freezing in winter, the water pipes had to be linked to parallel pipes of live steam which must be kept constantly hot. In addition, the water must be kept moving through the pipes continually and thence through an insulated outlet all the way to the river." The original pipe installations were wood stave construction, and this piping continued to be used until the 1970's (see Figure 1).

Figure 1: Wood Stave Piping Replacement in Dawson City Yukon (Circa 1970) INUVIK INFRASTRUCTURE One of the most significant infrastructure milestones in decade following World War 2 was the development of the community of Inuvik and its above ground piped water and sewer system, which was initiated by the chronic flooding and limited capacity of the nearby community of Aklavik. In 1957, John Diefenbaker's once-famous "northern vision" policy inspired the nation, and advanced further initiatives in northern infrastructure.

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In 1953, federal government survey teams fanned out across the Mackenzie Delta looking for a new spot on which to build the settlement that would replace Aklavik. They narrowed the choice to six on the east side and six on the west side of the delta. In November 1954 they picked East Three on the East Channel of the Mackenzie Delta, about 120 kilometres south of the Arctic Ocean. The large, flat area had a navigable waterway, room for expansion and wasn't subject to flooding each spring.

Construction of Inuvik began in 1955 and federal officials expected the town to be built by 1961 or 1962. It was the first time in Canada that a community would be built from scratch, giving new meaning to the term "government town."

Building on permafrost proved to challenge engineers and architects. They expected to find a metre of permafrost, but discovered that Inuvik sits on 350 metres of ground that is frozen year round. To prevent heat from warm buildings thawing the permafrost and causing them to sink, most structures sit on pilings drilled five metres into the ground with about half to one metre of space between the ground and the bottom of the building.

Inuvik's utilidor was originally constructed in one single enclosed conduit supported on wood piles; the utilidor included a dedicated pipe carrying high temperature hot water for buildings and freeze protection of the water and sewer mains (see Figure 2).

Figure 2: Inuvik Utilidor System (Circa 1960)

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INCREMENTAL IMPROVEMENTS The water and waste practices in the early days of small northern communities were very simple. Water was brought in by hand, from the nearest water source, "outhouses" were used for sewage waste, grey water was dumped adjacent to the houses, and garbage was burned in individual barrels near each household. Water supply advanced to the use of summer water points during the warmer months instead of bringing water by hand from a lake or stream (see Figure 3).

Figure 3: Summer Water Point In Rae Lakes, NWT Water and waste infrastructure in northern communities continued to make incremental improvements in the 1960's and 1970's as the subsistence lifestyles continued to decline, and more people moved to permanent settlements. Water and sewer tanks were becoming more common, along with indoor plumbing, but these were still limited.

Newer homes were equipped with wastewater holding tanks located on or beneath the floor of the house into which drained household waste from kitchen sinks, laundry, bathroom and toilets would drain by gravity. These tanks were normally larger than the water storage tanks, with a minimum tank size of 1200 litres..

Trucked delivery for water and sewer was the standard level of service in all but a few communities. A handful of larger communities started to develop piped systems, and this started the process of advancing water and sewer technology specific to cold region conditions with the application of shallow bury, insulated pipes and recirculating water systems (see Figure 4).

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Figure 4: Insulated Water and Sewer System in Rankin Inlet, Nunuvut (Circa 1980) One of the most significant policy decisions concerning water supply infrastructure occurred in the mid-1980's with the recognition that intestinal disease could be correlated to water use. As a result, a policy was put in place that water supply infrastructure would be required to deliver a minimum of 90 L/c/d in each individual in a community. This policy initiated a concerted effort to provide indoor plumbing to each household, and phased out the use of honey bags for sewage disposal. Keeping up with the ever increasing water demand were engineered water supply and sewage treatment facilities.

Water is an abundant resource in the north except for the fact it may remain frozen for over 6 months of the year. Access to a year round supply of water was a significant problem across the north which engineers solved by building large reservoirs with enough depth so the water would not completely freeze, and enough volume to accommodate what could be a nearly 2 metres of ice on the surface. The reservoirs were constructed of earth and lined with impermeable materials. Pumping systems adjacent to the reservoir fed truck fill points for distribution to the residents; chlorination equipment was provided as part of the truck fill station infrastructure.

Sewage treatment and disposal followed suite with water supply, and sewage lagoons became the technology of choice because of low cost and ease of operation and maintenance. The application of mechanical sewage was very limited, and in fact the only one community, namely, Carmacks, Yukon had a mechanical treatment system until the 1990's.

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THE FUTURE OF NORTHERN WATER AND SEWER The turn of the 20th century in the north has brought regulatory demands into the forefront of community infrastructure, for the better and worse of northern communities.

Continuing incremental improvements in water and waste infrastructure as a result of regulatory demands have benefited communities. On the other hand, regulatory scrutiny has placed many communities in positions where they have neither the financial nor human resources to address the regulatory demands.

Mechanical systems are becoming more common for water treatment, as senior governments work to meet national guidelines for drinking water quality. The continuing success of mechanical systems, particularly in small communities remains a function of the technical assistance provided by the senior levels of government. Small communities have limited financial and human resources for the operation and maintenance of complex water treatment systems.

Lagoon systems remain the most common form of sewage treatment, in spite of demands for more sophisticated technologies. Improving upon the performance of lagoons is occurring with the application of wetlands for tertiary treatment.

The key elements with the future of northern water and sewer are "appropriate technology", applied in a "northern context", and scheduled in an "incremental" timeframe.

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Cambridge Bay, Nunavut, Wetland Planning Study Robert H. Kadlec, PhD., P.E., Wetland Management Services, Chelsea, MI Ken Johnson, M.A.Sc., MCIP, P.Eng., Earth Tech Canada Cortney McCracken, EIT, Earth Tech Canada Published in the Journal of the Northern Territories Water and Waste Association. September, 2008.

DEL Communications Inc. Ken Johnson â&#x20AC;&#x201C; Editor.

Introduction Cambridge Bay, Nunavut has been planning for upgrades to the sewage lagoon systems, which includes a wetland area. As part of the design stage, a wetland planning report was prepared to estimate the water quality improvement that this engineered wetland project would achieve.

The study provides a unique look at wetland water treatment in cold climates. Treatment in a wetland is generally the result of a number of processes, such as settling, filtration, and bacterial action. These are aided by the presence of wetland vegetation, which is expected to be relatively sparse at the Cambridge Bay wetland; however, such vegetation does now exist in the depression ponds within the proposed wetland footprint. Some of these processes (mainly biological) occur much more slowly in cold temperatures, and the calculated water quality improvement was based on information and models from more southern climates. However, it is possible to predict the biological treatment efficiency of the Cambridge Bay wetland by applying temperature coefficients, and using very low rates for biological processes, compared to rates used in warmer climates.

Proposed Lagoon and Wetland System In 2005, the sewage treatment facilities at Cambridge Bay consisted of three natural lagoons totaling about 71,800 m3 capacity, and a limited wetland area. The Government of Nunavut realized that this existing sewage treatment system would not meet the needs of the projected population in 2020, and decided to investigate potential improvements to the lagoon system. Earth Tech Canada was retained for this planning related work.

The proposed configuration for the lagoon systems includes primary and secondary retention lagoons with 120,000 m3 storage volume, and constructed wetlands which will convey and further treat the water before discharge to the north arm of Cambridge Bay. The 2.93 ha wetland will be constructed by berming the flow path from the lagoons to the sea, and excavating to remove existing land features as needed. Discharge from the lagoons will be continuous during the summer season, of Figure 1. Cambridge Bay sewage lagoon and wetland.

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approximately three months duration. During this time, the 3 hectares of wetland in the flow path of the effluent (estimated to be at a mean depth of 30 cm) will provide about two weeks of detention in the wetland (See Figures 1 and 2).

Wetland Forecasting Procedure Constructed treatment wetland design generally involves three elements: hydrology and hydraulics; consideration of the pollutant and hydraulic loadings; and first order removal models.

The Cambridge Bay forecasting Figure 2. Cambridge Bay sewage wetland. calculations were implemented via spreadsheets on a desktop computer, because of the level of detail required in the modeling procedure.

The first step in predicting the wetland performance was a seasonal water budget calculation to examine how much water is present at various points in the wetland. This procedure took into account variables such as rainfall, evaporation, and plant transpiration, as well as the inlet water flow.

The next step was a review of the influent contaminant loads based on data taken in prior years at the lagoon discharge point. The wastewater from the community is high strength, due to restricted use of water; however, the water reaching the wetlands will have much lower contaminant concentrations due to extended lagoon treatment. The contaminant removal achieved by the wetland was calculated using pollutant mass balances, which required the selection of removal rate coefficients for each contaminant.

Contaminant Removal Rate Coefficients Suspended Solids A major function performed by wetland ecosystems is the removal of suspended sediments from water moving through the wetland. These removals are the end result of a complicated set of internal processes, and some of these processes such as resuspension and â&#x20AC;&#x153;generationâ&#x20AC;? of suspended material may increase the suspended solids at any point in the wetland. Temperature has little effect on suspended solids wetland treatment.

Accordingly, an estimated rate coefficient of 50 m/yr was chosen, which is sufficiently high to drive the wastewater TSS down close to the background value of 10 mg/L. Figure 3. Cambridge Bay CBOD performance.

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Carbonaceous Biochemical Oxygen Demand The Cambridge Bay wetland is expected to receive moderate incoming CBOD5. As temperature effects have been found to be minimal, the rate coefficient was selected as 30 m/yr, which is the 40th percentile of the distribution across other wetlands. This rate coefficient is sufficiently high to drive the wastewater CBOD5 down to 9 mg/L under current conditions, and 16 mg/L for future flows in 2025 (See Figure 3).

Nitrogen There appears to be little or no temperature dependence of organic nitrogen k-values. However, ammonia nitrogen removal in Cambridge Bay is likely to be achieved primarily by microbes which are very temperature sensitive. Therefore, relatively low rate coefficients were selected for nitrogen processing. The result is that the Cambridge Bay wetland shows lower TN removals than the comparison database, which reflects more southerly, warmer conditions (See Figure 4).

Phosphorus Phosphorus is a nutrient required for plant growth. There are two direct Figure 4. Cambridge Bay nitrogen performance effects of vegetation on phosphorus processing and removal in treatment wetlands: the plant growth cycle seasonally stores and releases P, thus providing a â&#x20AC;&#x153;flywheelâ&#x20AC;? effect for a P removal time series; and new, stable residuals are created, which accrete in the wetland (these residuals contain phosphorus as part of their structure, and hence accretion represents a burial process for P).

As most phosphorus removal is due to the burial of plant residuals, it is dependent on the size of the plant growth cycle, which is anticipated to be rather small for this far northern site. Accordingly, there will be a lower phosphorus removal at Cambridge Bay compared to southern wetland systems.

Pathogens Wetlands have been found to reduce pathogen populations with varying, but significant degrees of effectiveness. Bacteria in wetlands can be killed by ultraviolet radiation, eaten by nematodes, rotifers and protozoa, or removed along with particles in settling and trapping. Based on currently available treatment wetland data, pathogen removal is apparently not dependent on season or temperature.

Estimated Wetland Water Quality Improvements The new wetland system in Cambridge Bay is expected to complement the proposed lagoons, and provide good water quality improvement, especially for CBOD5 and TSS. Because of Cambridge Bayâ&#x20AC;&#x2122;s northern climate, CBOD5 and TSS removal are likely to be comparable to wetlands in other climatic regions, but nutrient removal will be less. Some removal of pathogenic organisms is anticipated, as there will be ample sunlight to promote UV disinfection in the wetland, as well as die-off due to cold temperatures. A two-log reduction (99%) is expected.

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The forecasts for water quality at the downstream end of the wetland are given in Table 1.

Table 1. Expected Water Quality into and out of the Treatment Wetland at Cambridge Bay Current Conditions

2025 Conditions

From Lagoons

Wetland Outlet

From Lagoons

Wetland Outlet

TSS

mg/L

50

13

75

18

BOD

mg/L

30

9

50

16

TP

mg/L

2.5

2.1

2.5

2.2

Org-N

mg/L

5

3.1

5

3.5

NH4-N

mg/L

10

9

10

9

NOx-N

mg/L

0.5

2.7

0.5

2.2

TN

mg/L

15.5

14

15.5

15

TKN

mg/L

15

12

15

13

FC

#/100ml

1,000

70

1,000

100

Conclusions The water reaching the Cambridge Bay wetland will have been subjected to very long detention in the lagoons, which will provide a good degree of water quality improvement. The wetland will then provide further water quality improvement, with particularly good results (results typical of southern treatment wetlands) predicted for CBOD5 and TSS removal.

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Aerated Lagoons in the Canadian North – Fort Nelson Facility Ken Johnson, M.A.Sc., P.Eng., Senior Planner and Engineer, Earth Tech Kriss Sarson, P.Eng., Program Manager, Community Services, Government of the Yukon Published in the Journal of the Northern Territories Water and Waste Association.

September, 2007. DEL Communications Inc. Ken Johnson – Editor.

Introduction Research on the application of aerated lagoons in the far north has been non-existent since facultative (non aerated) lagoons are the sewage treatment process of choice for most northern communities because of the cost effectiveness, simplicity of operation, and abundance of space available to most communities. This situation has been changing over the past decade as regulators have lobbied Water Boards, and pressured communities to improve effluent quality by applying conventional “southern” mechanical technologies.

This evolution has exhibited mixed results with “new” mechanical systems operating in the northern communities of Fort Simpson, Rankin Inlet, Iqaluit and Pangnirtung. Although it may be said that these systems are generally operating in compliance with the water licence parameters, the communities are faced with a legacy of sustaining these processes with limited financial and human resources. New challenges are emerging for these communities because of the demands for managing the significant biosolids waste stream produced by the waste treatment process.

Interest in the application of aerated lagoon systems in the far north is gaining momentum as regulators and senior governments recognize that this is appropriate technology based upon the successful operation of aerated lagoon systems in Alaska and the northern reaches of the provinces. The aerated lagoon system in Fort Nelson is one example of an aerated lagoon system operating in the near north, as well as aerated lagoon systems operating in northern Alberta, near Fort McMurray (See Figure 1)

Figure 1. Aerated lagoon near Fort McMurray.

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Aerated Lagoon Process and Configuration The aerated lagoon is a fairly straightforward, easy to operate technology that has been successfully used in cold climates. In the past, there was a degree of resistance to aerated lagoons in the North, primarily due to the higher energy costs and lack of appropriate cold climate aeration technology. Though higher energy costs are still a feature of operating costs in the North, aeration systems have been advanced sufficiently to allow for effective treatment in the North.

Throughout the past forty years, a number of process models have been advanced that describe the overall size and treatment efficiency of aerated lagoons. For the most part, they rely upon first order kinetics, and are therefore dependant upon the correct selection of the values for k and θ. For lagoon applications, the value of k can range from 0.14 to 0.3 and θ can range from 1.06 to 1.12. The size of the lagoon cells is also a function of the influent and effluent Biochemical Oxygen Demand (BOD) concentrations, along with the influent flow rate. Combined, these factors equate to the overall BOD load being “processed” by the lagoon.

The general configuration in an aerated lagoon uses a combination of completely mixed and partially mixed cells. A typical three cell aerated lagoon configuration is comprised of a completely mixed cell, followed by a partially mixed/plug flow cell, and then finally by a combination partially mixed/plug flow cell with a quiescent settling zone. The advantage of a three cell configuration versus a two cell system is process flexibility. It is advantageous to have the operating flexibility to take one cell out of service, while still maintaining effluent quality. This will become critical 20 or more years down the road, when cell desludging may be required.

The process concept of an aerated lagoon system allows for a significant portion of the organic load to be taken up in the first cell (completely mixed), so for this reason a slightly higher reaction rate constant may be applied to this cell, and a more modest one for the subsequent partially mixed cells. With this type of model there is a degree of variability, and the effluent BOD values for each of the cells are approximated, along with the appropriate size of the cells.

Other factors have to be considered with respect to the layout of the facility, such as subsurface conditions, site topography, ease of geo-membrane liner application, and the treatment plant building layout.

In a conventional mechanical secondary wastewater treatment plants, aeration requirements are dictated by the process air requirements and not mixing requirements. However, in an aerated lagoon application, the opposite is true. The aeration for the lagoon cells is generally supplied by a fine bubble aeration system supplied by a defined number of process air blowers.

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Performance of Fort Nelson Aerated Lagoon The aerated lagoon system serving the community of Fort Nelson is example of the successful operation of an aerated lagoon in a cold climate (See Figure 2). The average performance for the aerated lagoon over the past 7 years (2000 to 2006) has maintained BOD and Total Suspended Solids (TSS) removal greater that 80 percent (See Table 1).

Average effluent BOD5 and TSS has been less than 25 mg/L for both parameters for the years 2004, 2005, and 2006; average effluent fecal coliforms have been less than 40,000 CFU per 100 mL (See Table 2).

Figure 2. Fort Nelson aerated lagoon system.

Table 1. Average Yearly Performance for Fort Nelson Aerated Lagoon Year 2000 2001 2002 2003 2004 2005 2006

Average % BOD Removal 79 68 82 83 83 83 88 Average 81

Average % TSS Removal 86 92 86 84 81 88 90 Average 87

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Table 2. Average Influent and Effluent Quality for Fort Nelson Aerated Lagoon Year

2004 2005 2006

Influent BOD5 mg/L 140 115 133

Effluent BOD5 mg/L 24 19 17

Influent TSS mg/L 147 197 200

Effluent TSS mg/L 22 22 19

Influent FC CFU/dL 3.0x106 2.9x106 2.0x106

Effluent FC CFU/dL 17.1x103 37.4x103 1.3x103

Winter performance during the months of December through March (2000 to 2006) has produced an average BOD5 removal in the range of 70 to 93 percent, and an average TSS removal in the range of 72 to 98 percent.

Table 3. Average Winter Temperatures in Fort Nelson

Average Temperature (degrees C)

November -13.0

December -19.9

January -21.2

February -16.1

March -7.7

Advancing Applications of Aerated Lagoons in the Far North In 2004, Dawson City and the Government of the Yukon evaluated the application of aerated lagoon technology for producing a secondary non-toxic effluent compliant with the Fisheries Act, Water License and the Court Order. This work included a preliminary site selection and costing along with an aerated lagoon pilot test. Initial sites were selected for a 3 cell system comprised of 2 aerated cells (15 day retention each) and one facultative cell (60 day retention). The pilot plant results confirmed that an aerated lagoon had the potential to produce a non-toxic secondary effluent without the need for a facultative cell. This work was advanced to the preliminary engineering of an aerated lagoon system to serve Dawson City, and design work may proceed in 2007, with anticipated construction to be completed by 2010.

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Figure 3. Aerated lagoon pilot program in Rae, Northwest Territories.

Independent aerated lagoon research by Environment Canada is also underway in the community of Rae, Northwest Territories. The research is focusing on the application of submerged and surface aeration systems, and the performance of these systems during the winter months.

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THE SOCIAL CONTEXT OF WASTEWATER MANAGEMENT IN REMOTE COMMUNITIES Ken Johnson, M.A.Sc., MCIP, P.Eng. Earth Tech Canada Abstract The development and sustaining of infrastructure in remote communities has always been influenced by a variety of factors. Over the past decade, the complexity of these factors has increased substantially with changes to the available financial resources, the administrative structures, the operational responsibilities, and the regulatory environments. Many of these changes have increased the overall complexity of infrastructure development, and sustainability in remote communities, particularly at the community level. Many communities are finding the demands of these complexities to be well beyond their financial and administrative resources, and as a consequence are placing themselves in very undesirable situations with regard to community funding and regulatory compliance.

The challenges associated with wastewater management in remote communities occur in the areas of science, applied science, and social science. The science of wastewater management, particularly northern communities, remains incomplete, and consequently the regulatory frameworks are not realistic. The applied science or "engineering" of wastewater systems in remote communities should follow the key principles of appropriate technology, community context, incremental improvement. The social science associated with wastewater management in remote communities presents a multitude challenges which include, administrative, financial, and human resources.

The ecosystems of the remote regions of Canada are unique and fragile, and must be protected.

However, to date, the protective measures for these ecosystems have not been developed or implemented based upon the necessary northern science, applied science, and social science information.

Introduction On a political scale the remote areas of Canada constitute as much as 45% of Canada's land mass, including the regions of the Yukon, Northwest Territories, Nunavut, Nunavik (northern Quebec), and Nunatsiavut (northern Labradour) are included (see Figure 1). By contrast this vast region is populated by a mere 100,000 people occupying 90 communities. Which is an average Figure 1. Remote areas of Canada

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Figure 2. Defining remote areas by temperature – arctic region is defined by 10C isotherm. population of 1100 per community. In fact the communities of Whitehorse (24,000), Yellowknife (19,000) and Iqaluit (7,000) account for about half of the population making the average population for realistically less than 600 people per community.

The remote areas of Canada, and the world are most often defined by temperature, as well as geography. In a North American context, all of Canada, with the exception of the west coast, is considered very cold, and in fact, the United States considers the cold region to be the northern portion of the lower 48 states, rather than the state of Alaska (see Figure 2). The subarctic and arctic regions of Canada are considered to be beyond "very cold". The scientific approach defines the Arctic as the area where average temperature for the warmest month of the year (July) is below 10°C (50°F).

This macro scale for remote areas is very different from the micro scale that most remotes communities must function within. The limits of remote communities are often defined by the all weather road system that provides access to facilities such as the airport, the water source or the waste management area (see Figure 3). The interactions between these built infrastructure features of remote communities have positive and negative interactions within themselves, as well as the built features associated with human habitation.

The development and sustaining of this infrastructure in remote communities has always been influenced by a variety of technical, financial, administrative, operational and regulatory factors.

Over the past 10 years the complexity of these factors has increased substantially with changes to the available financial resources, the administrative structures, the operational responsibilities, and the regulatory environments.

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Many of these changes have increased the overall complexity of infrastructure development, and sustainability in remote communities, particularly at the community level. Many communities are finding the demands of these complexities to be well beyond their financial and administrative resources, and as a consequence are placing themselves in very undesirable situations with regard to community funding and regulatory compliance.

Figure 3. The opportunities and constraints of remote communities The challenges associated with wastewater management in remote communities occur in the areas of science, applied science, and social science.

Science of Wastewater Management The science of modern wastewater treatment systems may be described by a number of unit processes. Each process provides an increasingly higher quality of sewage effluent applying various physical, chemical and biological actions. The unit processes include: • • • • • •

preliminary treatment primary treatment secondary treatment tertiary treatment disinfection residuals management.

Preliminary treatment is a physical process which may be described in the exaggerated, but very simple terms of coarse screening of the sewage influent to remove “two by fours” and

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“bicycles.” This exaggeration has occasionally been known to be true, but in a generally expected scenario, the preliminary treatment would remove large objects such as rags or toys.

Preliminary treatment may also include such processes as communition, flow measuring, and pumping. Primary treatment is a physical process of suspended solids reduction by either sedimentation or fine screening. The sedimentation process uses gravity in a quiescent basin to settle out the solids, or a fine screen to block passage of solids. The solids, either settled or screened, are removed and processed further as part of the residuals management.

Secondary treatment is a biological process of enhanced biodegradation of sewage to reduce the biodegradable material within the sewage. The enhanced conditions for biodegradation include increased availability of oxygen, and an increased number of organisms in the treatment basin.

The organisms within the basins may be either suspended in the sewage or attached to a fixed media. Tertiary treatment may be either a chemical or biological process of phosphorus removal, ammonia removal, or other enhancement to remove sewage constituents such as solids or biodegradable material.

The removal of any remaining pathogenic organisms in a sewage effluent is the primary purpose of disinfection. The common processes used in disinfection are chlorination, ultraviolet radiation, and ozonation. These methods of disinfection operate on the principles of either direct oxidation of the pathogenic organisms (chlorination or ozonation) or mutation of the organism to kill it (ultraviolet radiation).

Residuals management involves a biomass reduction and disposal. The first stage in residuals management is to condition or stabilize the biomass by further biodegradation or digestion employing either an aerobic process (air supplied) or an anaerobic process (no air supplied). The second stage is to reduce its volume by removing the liquid from the biomass by either a physical process or a drying process. The stabilized biomass may also be disposed of directly by application to agricultural land, if it is available.

Biodegradation, in addition to sedimentation for solids reduction, is a fundamental process for any wastewater treatment process beyond primary treatment, and is an essential process to produce effluent quality appropriate to minimizing public health and environmental impacts.

Biodegradation is, however, significantly reduced by cold temperatures, which is an important factor for the performance of lagoon systems. Fortunately, there are bacterial called Psychrophiles, which are cold-loving, and have optimal temperature for growth at about 15°C or lower, and a maximum temperature for growth at about 20°C, and a minimal temperature for growth at 0°C. In the summer months the warmth and sunlight promote the greatest biodegradation activity in lagoon sewage treatment systems, and the systems must be operated accordingly. The general operating scenario for lagoons in cold regions is a 365 day retention followed by an annual decant.

During the winter months with the absence heat and sunlight, the primary process for sewage treatment in lagoons is sedimentation. Sedimentation is also influenced by the cold. Settlement

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velocity depends on the viscosity of the water it; increased water viscosity implies a slowing of the settling process by a factor of 1.75 for water at 1 C compared to water at 20 C. The science of wastewater management (treatment and disposal) in remotes areas, particularly northern regions, remains incomplete, and consequently the regulatory frameworks are not generally realistic. For example, the practice of just wastewater sampling has inherent problems in the north from the seemingly simple process of getting a water sample to "the lab", to the inability to represent a source environment in a laboratory conditions.

Applied Science of Wastewater Management Applied science is the process of taking the science and applying it to specific applications.

Thinking outside the “box” is necessary for applied science in remote communities in response to the challenges of extreme cold, very limited access, extraordinary costs, and scant resources.

These are a few of the “routine” challenges that engineers, as well as suppliers, contractors must face in designing and constructing wastewater treatment facilities for remote areas.

The applied science or "engineering" of wastewater systems in remote communities should follow the key principles of appropriate technology, community context, incremental improvement. These principles have been applied inconsistently to projects in remote communities, and consequently a significant number of projects are not meeting the performance expectations of the communities, and the regulatory authorities.

Appropriate technology suggests that whatever process is being applied for wastewater treatment must consider the biophysical context of the project site, which includes location, climate, landforms, and possibly the native vegetation. Cold weather and distance are the two major factors in the consideration of appropriate technology. Although engineering designs may take into account measures to prevent wastewater facilities from freezing, it is also prudent to design the means to “thaw” a facility in the event it does freeze; in fact it may be appropriate to state that it is not a matter of if the facility freezes, but when it freezes.

Distance is the second factor influencing appropriate technology. Remote communities, by definition, are located at a great distance from what would be considered the “normal” amenities available to a community. Consequently, the resources available for routine operation, and maintenance may not be available at the facility site, and may be not be available for days or more,and may cost extraordinary amounts of money to mobilize.

Appropriate technology for wastewater treatment in remote locations may in fact make use of the extensive cold and limited warmth. One particular application is the concentration of sewage biosolids through the freeze-thaw process, and subsequent composting through the limited summer months. This process is just beginning to be applied in the community of Iqaluit, Nunavut.

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The community context of a wastewater treatment process has some overlap with the biophysical context of “appropriate technology”, but it is specific to the built environment of a community.

A remote community of 100 people has a very different “community” in comparison to a remote community of 500 people. One would expect that the smaller community would have significantly less human resources for the project implementation as well as the operation and maintenance of any wastewater facility. The smaller community would also have less resources for the construction of a wastewater facility.

Incremental improvement to wastewater treatment is simply a remote context of the phrase that “Rome was not built in a day”. Project planning is an inherent part of any facility implementation, and in a remote context it is has been recognized that at least a 5 year cycle from planning through to project completion is needed. Year one of the cycle occupies consultation with the community. Many remote communities are aboriginal and consequently may a different cultural perspective on wastewater treatment. Efforts to consult and education communities on the benefits to wastewater treatment are sometimes difficult, but the return on this benefit is significant. Year two of the cycle occupies the technical activity of “engineering” the facility along with continuing community consultation. Years three and four occupy construction, which has a limited window of the year because of the material supply, and cold weather. Year five occupies the critical post construction period where the facility becomes operational; this period may in fact “make or break” the project because the community must take ownership of the functional, as well as the physical attributes of the project.

The other benefits of incremental improvements apply to the financial planning and community employment. A multi-year implemental allows the community to reduce the cash flow requirements, and provide longer term employment opportunities for the residents of the community.

Social Science of Wastewater Management The science and applied science of wastewater treatment are subjects that need more attention, but attention has been given to these important factors over the past several decades. The social science of wastewater management in remote communities has, however, received much less attention. Even the term “social science” may not be a particularly all encompassing phase to apply to “all of the other stuff” associated with wastewater management in remotes communities, but it is a start.

The social science associated with wastewater management in remote communities presents a multitude of challenges which include, administrative, financial, and human resources. Any remote community, regardless of size, has the need for a fully funded, fully staffed, and fully trained community administration; however, this is seldom the case.

The administrative challenges include multiple levels of government; limited resources; and changing rules. The multiple levels of government in remote communities may include several levels of local representing the aboriginal community, as well as the non-aboriginal community;

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WCWWA 2007 Conference & Trade Show October 23 – 26, 2007 Edmonton, Alberta

the territorial government, as well as the land claim by the aboriginal community; and the federal government, which may have several departments working independently to represent their own mandates. In some communities the various levels of government may number 6 or more.

The resources available to communities have been a dynamic environment for remote communities over the past several decades. The “devolution” of responsibilities has been ongoing in response to demands for autonomy from some communities, as well as the downsizing of territorial governments. The devolution process has had varying degrees of success. The latest chapter in the Northwest Territories is the so-called “New Deal” which was implemented in 2007, and provides a block funding to all communities. Some communities are “running” with the opportunity and other communities are overwhelmed. The “New Deal” is a good example of the changing rules that remote communities must cope with. In spite of the best conceived and comprehensive “roll out” possible, the “New Deal” will fail in some communities, as this change in the rules, along with other changes associated with many other administrative aspects of the community, are beyond the community’s capacity.

The financial challenges include financial management; capital funding; and operation and maintenance funding. Financial management is a challenge for any community, and represent a continuing challenge for many remote communities. Every remote community has a community budget that is proportionately larger than what would normally be expected in a southern geographic context, and the financial management of this budget requires skill and training that many communities do not possess. Funds for capital, and operation and maintenance from the senior governments have diminished significantly over the past decade, and communities are being encourage to be more self sufficient for financial resources.

The human resources challenges include hiring staff; training staff; and retaining staff. Human resources may, in fact, be the most challenging aspect of the social science of wastewater management. People represent a very dynamic environment, which has been plagued with a chronic lack of resources for hiring, training, and retaining.

An eye opening example of the financial challenges faced by remote communities is presented with the operation and maintenance costs for water and sewer in the remote communities of Whati, in the Northwest Territories, and Grise Fiord in the Nunavut Territory; Grise Fiord is the northern most community in Canada.

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WCWWA 2007 Conference & Trade Show October 23 – 26, 2007 Edmonton, Alberta

Figure 4. Location of Whati, NWT, and Grise Fiord, Nunavut

Table 1. Whati, NWT Operation and Maintenance costs Year Water$ Sewer $ Total$ 2001 167,800 71,900 239,700 2002 184,600 79,100 263,700 $580 per capita per year in 2002 or 2.3 cents per litre for water and sewer Water use: 11.5 million litres per year or 70 litres per capita per day Table 2. Grise Fiord, Nunavut Operation and Maintenance costs Year Water $ Sewer $ Total $ 2001 234,391 100,200 334,591 2002 255,959 109,696 365,655 $2,240 per capita per year in 2002 or 6.4 cents per litre for water and sewer Water use - 5,678,500 litres per year or 95 litres per capita per day In comparison the cost of water is 0.12 cents per litre in Edmonton.

Conclusions Lagoons have been the sewage treatment process of choice for most remote communities because of the cost effectiveness, simplicity of operation, and abundance of space available to most communities. This situation has been changing over the past decade as regulators have lobbied Water Boards, and pressured communities to improve effluent quality by applying conventional “southern” mechanical technologies.

This evolution has exhibited mixed results with “new” mechanical systems operating in the northern communities of Fort Simpson, Rankin Inlet, Iqaluit and Pangnirtung. Although it may be said that these systems are generally operating in compliance with the water licence parameters, the communities are faced with a legacy of sustaining these processes with limited

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financial and human resources. New challenges are emerging for these communities because of the demands for managing the significant biosolids waste stream produced by the waste treatment process.

The ecosystems of the remote regions of Canada are unique and fragile, and must be protected, hence the need for wastewater treatment. Public health must also be protected, and wastewater treatment must serve this purpose as well. However, to date, the protective measures for these ecosystems and public health have not been developed or implemented based upon the necessary science, applied science, and social science information.

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CSCE 2007 Annual General Meeting & Conference Congrès annuel et assemblée générale annuelle SCGC 2007

Yellowknife, Northwest Territories / Yellowknife, Territoires du nord-ouest June 6-9, 2007 / 6 au 9 juin 2007

Engineered Improvements to Sewage Treatment System in Cambridge Bay, Nunavut Ken Johnson and Michelle Yu, Earth Tech Canada Navjit Sidhu, Government of Nunavut Abstract The existing sewage facility serving the community of Cambridge Bay is a typical northern lagoon system developed through a system of natural ponds, and refined with limited containment and control structures.

All of the improvements to the pond system were essentially not engineered and as a result, the system has been a continuing source of concern for both the community and the regulatory organizations.

A planning study was undertaken to try and identify a number of new locations for the community to relocate the sewage lagoon system, however, none of the proposed sites have presented a satisfactory alternative in terms of community, environmental, or financial impact. As an alternative to the development of a new site, “engineered” improvements to the existing site have been developed.

The engineering of improvements to a natural system originates from the analysis of the system process and system capacity, and the identification of elements that may enhance the process and capacity. In the case of the Cambridge Bay facility, the existing pond system has the inherent facilitative process to treat sewage, and may be redeveloped to provide the appropriate long term capacity.

A series of site investigations including wastewater sampling, and a topographic survey provided the basis for making these conclusions. The next step in the process is the engineering and implementation of the necessary improvements. A key to the engineering is the identification of appropriate materials and methods to carry out these improvements. The use of available soil materials from the community provides the basis for implementing the improvements in an economical and incremental manner.

1. Introduction A series of potential waste management areas for the community of Cambridge Bay were identified based upon the community’s interest in relocating the exiting lagoon facility. The planning analysis of the potential new sites included a "proximity" analysis of human activities and natural features; an analysis of potential road access to each site; an estimate of capital and operation and maintenance costs; and general site development configurations for the sites.

Water sampling of the existing waste management facilities was also carried out to provide additional information to the existing sampling studies. A report suggested that the lagoon system of treatment is working satisfactorily to reduce the concentration of sewage contaminants to the acceptable level prior to discharge into the environment. Based upon the input from the community, and the direction provided by the Government of Nunavut, preliminary engineering for redevelopment of the existing sewage treatment

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proceeded. It is anticipated that the preliminary engineering information will provide a basis for a submission to the Nunavut Water Board for approval of the improvements. Community stakeholder consultations on the redevelopment of the existing site will also continue.

In support of advancing the redevelopment of the existing waste management sites, a topographical survey, and a geotechnical investigation of the sites were undertaken. The topographic survey generated accurate contour information for the lagoon pond areas, and the discharge stream; the geotechnical investigation provided information on the soil conditions around the sites, and information on the soil materials around the community that may be used for the construction of any redevelopment work.

2. Community Information The community of Cambridge Bay is the largest community in the Kitikmeot Region of Nunavut, and is geographically situated on the Dease Strait between the Queen Maud Gulf and the Coronation Gulf in the North West Passage. It is located on 69° 07' N latitude and 105°03' W longitude, and it is approximately 960 air km north east of Yellowknife. It is one of the most westerly communities of Nunavut, with a population of 1,609 in 2006. Recent population figures for the community point to higher than normal growth.

The Hamlet of Cambridge Bay is situated in an area of sags and swells, dry debris-strewn knolls, and moist depressions, with limited vegetation. The climate can be characterized by long cold winters and short cool summers, and the daily average temperature is -14.4°C. The average total annual precipitation is 13.9 cm, consisting of 82.1 cm of snowfall and 7.0 cm of rainfall. The July mean high is 12.3°C, and the mean low is 4.6°C. The January mean high is -29.3°C, and mean low is -36.3°C. According to the 2004 Hamlet of Cambridge Bay Community Economic Development Plan, Cambridge Bay is a very progressive community with unlimited potential. It is expected that, being the hub of Kitikmeot Region, the community will experience a substantial economic growth in future years. The proposed Bathurst Inlet port, road, health center projects, and mining ventures, will increase social and tourism activities in the community, and will also place a significant burden on the existing infrastructure.

3. Existing Services The water use and waste disposal in the Hamlet of Cambridge Bay is regulated by a Type B Water License. The present source of the community's potable water source is Water Lake located approximately 3 km north of the community (see Figure 1). Water trucks are used to distribute water to houses in the community; water uptake from Water Lake totals approximately 20 truckloads per day 3 (12000 L per truckload). The current water consumption is approximately 87,600 m /year, although the 3 current water license allows for the removal of 70,000 m of water from Water Lake annually.

Sewage is collected from the community by sewage trucks, and discharged into a sewage lagoon system, which is used to treat wastewater for the community. Currently, on average 16 truckloads (12,000 L per truckload) of sewage are discharged into the lagoon each day. The existing lagoon is located approximately 1.5 km north east of the community, and has been in use for over thirty years. The system consists of several natural ponds connects in series, with a volume of approximately 72,000 m3 based on the normal operating level in the lagoon ponds.

The sewage is discharged into the first pond of the lagoon at truck discharge site. The treated sewage the lagoon is ultimately channelled into Cambridge Bay. Currently, there is no discharge control structure in the lagoon, therefore, sewage effluent from the lagoon is discharged continuously. The lagoon is annually flooded due to the spring runoff from the adjacent catchment areas into the lagoon.

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Figure 1. Cambridge Bay water and sewer facility locations.

There are several issues of concern with the system. The main concern is the influence of large spring runoff flows into the lagoon, which reduce the storage and treatment capacity of the lagoon due to the magnitude of the flows. The other concerns with the system include the ultimate treatment capacity of the lagoon, and the discharge point of the lagoon, which is within 450 metres of the community.

The results of limited effluent sampling suggest that the concentration of all the effluent discharge parameters (contaminants) collected from sampling points were below the respective Municipal Waste Water Effluent Guidelines. The overall sampling results suggested that the lagoon system of treatment is working satisfactorily to reduce the concentration of sewage contaminants to the acceptable level prior to discharge into the environment (Cambridge Bay).

4. Sewage Characteristics and Quantity Wastewater generated in Cambridge Bay is domestic in source and characteristics. The wastewater quality from the community may be considered to be a "high strength" waste because of the use of a

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trucked sewage and water system. The "high strength" condition is typical for trucked sewage and water systems due to the low water usage, which translates into low dilution of the raw sewage.

The Hamlet of Cambridge Bay's current water license stipulates the effluent requirement. The current water license came in effect on September 1, 2002 and expires on August 31, 2007. The conditions applying to waste disposal are stipulated in Part D of the license and presented in Table 1.

Table 1. Effluent Quality Standards Parameter Faecal Coliforms BOD5 Total Suspended Solids Oil and grease pH

Maximum Average Concentration 1 x 106CFU/dl 100 mg/L 120 mg/L No visible sheen Between 6 and 9

Based upon population projection by the Nunavut Bureau of Statistics, the generation of sewage waste is estimated for the next 20 years (starting from 2006). Table 2 presents the summary of sewage generation in the next 20 years.

Table 2. Estimated Sewage Waste Volume Generation for the Hamlet of Cambridge Bay, 2007 to 2025

Year

2007 2010 2015 2020 2025

Population

Daily Flow

Yearly Flow

m3/day

m3/year

1,642 1,752 1,939 2,137 2,360

230 356 271 299 330

83,906 89,527 99,083 109,201 120,572

Notes: 1. Population projection data (2020-2025) based on 2% growth rate (determined from GN population projection data).

2. Population projection data (2020-2025) extrapolated by Earth Tech.

3. Average daily sewage waste generation rate per person is 140 litres.

5. Sewage Lagoon Improvements The lagoon sample results indicates that the concentration of the effluent discharge parameters is below the concentration required by the water license. The sampling results suggest that the lagoon system of treatment is working satisfactorily to reduce the concentration of sewage contaminants to the acceptable

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level prior to discharge into the environment. The existing lagoon system may still serve the Hamlet as a sewage treatment facility for next 20 years with the improvements that appropriately address all the issues of concern.

Table 3. Sewage Lagoon Design Criteria Design Treatment Capacity: Design Effluent Quality: Faecal Coliforms BOD5 Total Suspended Solids pH Lagoon Pond Area: Average Depth: Storage Volume: Freeboard: Discharge: Supplemental Treatment:

120,000 cubic meters per year (20 year horizon) 1 x 106CFU/dl 100 mg/L 120 mg/L Between 6 and 9 14.8 hectares 0.81 meters 120,000 cubic meters 1 metre Annually Wetland

The current sewage generation rate is approximately 70,080 cubic meters per year. The existing high water level of the lagoon is approximately 8.85 metres above sea level. On the basis of hydraulic retention time (HRT), the current lagoon may achieve a HRT of approximately 375 days based on the current sewage generation rate. This is based on a rough volume estimate of 72,000 cubic meters for the existing lagoon storage. This HRT achieves the maximum benefit from retention during the limited summer season.

By the year of 2025 the sewage generation rate would be approximately 120,000 cubic meters per year.

The HRT would be reduced to approximately 219 days based upon the current capacity. A 219 day HRT may not achieve the maximum benefit from complete sewage retention during the limited summer season (June, July, and August) resulting from solar energy, and biological activity. The lagoon volume may be increased by increasing the high water level. A water level elevation of 9.5 metres will provide a lagoon volume of 119,000 cubic meters, and the HRT will be approximately 360 days. The increased water level of 9.5 metres would be achieved by construction and reinforcement of berms.

5.1 Primary Cell In order to improve the lagoon performance and to extent the lifetime of the lagoon, a primary cell is proposed at northwest side of the main pond. A submerged berm is proposed to separate primary cell and secondary cell (see Figure 2). The sewage would then be pre-treated, and much of the suspended solids would be settled out within the primary cell before sewage enters the secondary cell. The sludge settled in primary cell could be removed on a period basis.

A truck discharge flume will be located at the west end of the primary cell. The sewage truck will use the discharge flume to deposit raw sewage into the lagoon. There would be a treated lumber wheel stop and bollards at the edge of the pad to prevent the truck from backing into the sewage lagoon. From the truck pad the offload chute consisting of an 800 millimetre diameter nestable culverts will run down the inside slope of the berm to the rip rap area at the bottom of the primary cell.

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Figure 2. Submerged solids retention berm 5.2 Decant System A mobile decant system will be located at the opposite end of the lagoon to the truck discharge flume.

The lagoon will be annually discharged by pumping effluent into the receiving environment from the lagoon using a powered pump. Given the maximum annual sewage volume of 120,000 m3, a mobile decant facility which includes a diesel engine driven self priming pump is proposed to decant the lagoon annually over a period of three weeks.

5.3 Spillway A spillway is proposed in order to control the lagoon high water level in the event of an extreme runoff situation. The spillway route would be same to the discharge route as the existing lagoon system. Any water about high water level (9.5 metres) would overflow through the spillway on the proposed retention berm.

5.4 Supplemental Wetland Treatment An engineered wetland is proposed to further treat the effluent from the lagoon system. Water quality improvement is improved through a variety of natural processes that occur in wetlands. The technology of seasonal discharge from a lagoon to wetlands has been demonstrated to provide significant sewage treatment capabilities. Using natural filtration, sedimentation, and physical or chemical immobilization, the soil and plants of wetland systems effectively absorb and retain suspended solids, carbonaceous and nitrogenous components of BOD, nutrients (including phosphorus), pathogenic organisms including coliforms, and other pollutants. Although there is a limited wetland downstream of the existing lagoon, the performance of this wetland may be greatly enhanced by constructing an engineered wetland to optimize the flow and vegetation.

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Figure 3. Lagoon Improvements and discharge.

5.5 Discharge Point The effluent will be diverted around an existing the bulky metal dump site with a pumped decant system.

The effluent would enter the engineered wetland before crossing the existing road to the south. Twin 500 mm culverts running under the road will be required. From this point, the effluent will flow into the bay.

The proposed discharge point would 420 metres east of the existing discharge point, and 675 metres east of the community. This changed point would avoid the conflict with the discharge proximity to the community.

5.6 Runoff Diversion One of the major concerns regarding the existing lagoon is the spring runoff flows into the lagoon, which influences the performance and capacity of the lagoon. Consideration of this concern suggests that runoff diversion berms would be required. The proposed runoff diversion berms are identified based on the watershed contours. The runoff diversion berms would divert most of the runoff around the lagoon either to the east or west.

5.7 Capital Cost The cost of a new lagoon site would be more than $3.7 million. In comparison, it would cost approximately $1.8 million (Class C estimate) to improve the existing lagoon.

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6. Conclusions and Recommendations The existing lagoon system appears to be functioning to reduce the concentration of sewage contaminants to the acceptable level prior to discharge into the environment. Therefore, it is feasible to use the existing lagoon site with improvements regarding the current concerns. Redevelopment of the existing site is the more cost effective option if all the concerns regarding to the existing lagoon site configuration and operation are addressed properly.

The improvements to the existing lagoon system can be planned and constructed in an incremental fashion according to the priority of each component of the improvement. This will give the community a funding and manpower flexibility regarding the ultimate development of the lagoon improvements.

The recommended construction priority would be as follows: 1.

2.

3.

4.

5.

6.

Improve flow under the road along the existing discharge channel by replacing culverts.

Construct runoff diversion berms to divert runoff around from the lagoon.

Construct retention berms and submerged berms related to capacity increase.

Purchase decanting equipment.

Extend access road and build the truck discharge flume.

Construct the engineered wetland and the new discharge point.

7. References

Earth Tech, February 2006, Hamlet of Cambridge Bay Integrated Sewage and Solid Waste Facilities Design – Progress Report No. 1 (Research Report).

Earth Tech, July 2006, Hamlet of Cambridge Bay Sewage and Solid Waste Facilities – Planning Report.

Earth Tech, August, 2006, Cambridge Bay Waste Facility Improvements Sewage Analysis – Summary Report.

Earth Tech, April, 2007, Cambridge Bay Waste Facility Improvements, Preliminary Engineering Report for Redevelopment of Existing Sewage Lagoon.

Inuvialuit Environmental and Geotechnical, October 2005, Cambridge Bay Municipal Sewage Lagoon and Waste Facilities Assessment (GN Project No. 04-4807).

Municipal and Community Affairs, GNWT, April 2003, Guidelines for the Planning, Design, Operation, and Maintenance of Sewage Lagoons in the Northwest Territories.

Northwest Territories Water Board, 1992, Guidelines for the Discharge of Treated Municipal Wastewater in the Northwest Territories.

Nunavut Bureau of Statistics http://www.stats.gov.nu.ca/statistics%20documents/pop_projections_by_comm.pdf

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CSCE 2007 Annual General Meeting & Conference Congrès annuel et assemblée générale annuelle SCGC 2007 Yellowknife, Northwest Territories / Yellowknife, Territoires du nord-ouest June 6-9, 2007 / 6 au 9 juin 2007

Wetland System for Treatment of Landfill Runoff in Iqaluit, Nunavut Ken Johnson, and Dong Li, Earth Tech Canada Geoff Baker, and Mark Hall, City of Iqaluit Abstract The City of Iqaluit produces approximately 10,000 m3 of compacted waste, which enters the landfill each year, and includes residential, commercial and industrial wastes. The City’s landfill operation uses the area method, which involves placing waste above grade against a berm, compacting the waste using a wheeled loader, and covering the waste using a wood mulch material.

A landfill expansion has been an expected part of the continuing operation of the existing site for the past 6 years, and the implementation of the expansion is an absolute necessity to properly manage the site.

With the expansion comes the necessity to manage the runoff in and around the site in order to minimize the impact of contaminated runoff that is inherent to any landfill operation.

Innovation is coming forward from the City with the consideration of wetlands to provide “treatment” to the runoff before it is discharged into the environment. Wetland treatment systems have been applied to municipal wastewater treatment in the north for the past decade, but landfill runoff has not been considered in the application of this process. Regulatory scrutiny and incremental improvements by the communities has made landfill runoff treatment a new priority for water licence compliance.

The City of Iqaluit is continuing to take significant steps to improve its waste management practices. The City is devoted to being environmentally responsible, and compliant with the regulatory requirements of the various local, territorial and federal agencies. The City is not only responding to the current needs of the community, but is also committing to solid waste planning for the future.

1. Introduction The City of Iqaluit produces approximately 10,000 m3 of compacted waste, which enters the landfill annually, including residential, commercial and industrial wastes. The landfill site relies on the local permafrost regime to provide a low permeability barrier to control the subsurface runoff.

The on-site surface runoff is comprised of contaminated surface runoff originating from the melt water from the spring freshet and runoff from summer precipitation. The surface runoff sampling results in June 2006 suggest that the landfill runoff needs to be appropriately managed, and direct discharge into the environment should be controlled.

The average monthly temperatures in Iqaluit vary from 2.2 to 7.7 degree Celsius from June through September and -4.4 to -28 degree Celsius from October through May. The average annual precipitation is 198 mm of rainfall and 236 cm of snowfall for a mean annual precipitation total of 412 mm.

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Landfill runoff sampling at the landfill site was completed in 2004 and 2006. The major parameters exceeding the Guidelines for the Discharge of Treated Municipal Wastewater in the Northwest Territories (1992) in 2006 sampling event are Biochemical Oxygen Demand (BOD5), Total Suspended Solid (TSS) and metal contents including Aluminum, Iron, Copper, Lead, Manganese and Zinc.

Four drainage control ponds are located in the landfill area at West 40 Landfill site. An existing pond was augmented by three new ponds in 2006. A runoff retention pond was also constructed in 2006 as the area where accumulated runoff in the control ponds may be pumped to. The runoff retention pond was constructed in original ground with a compacted base. The base materials are typically loamy sands based on the grain size distribution. The loamy sand is a poorly graded material with limited permeability, and has significant fractions of silt and gravel sized materials A proposed wetland treatment area is located east of the runoff retention pond. The slope in the proposed wetland location is generally from west to east, which provides a positive drainage slope by gravity for the proposed wetland.

2. Wetland Systems Both natural and constructed wetland systems have been used to treat a variety of wastewaters including runoff from landfills. The use of constructed wetland, rather than natural wetlands, may be preferred because constructed systems may be specifically engineered for the particular wastewater characteristics. Constructed wetlands allow a greater degree of control of substrate, vegetation types, flow characteristics, and flexibility in sizing. Constructed wetlands are engineered systems that have been designed and constructed to utilize the natural functions of wetland vegetation, soils, and their microbial populations to treat contaminants in various wastewater streams.

Constructed wetlands are categorized into two main groups: surface flow (SF) and subsurface flow (SSF).

Factors to be considered include land area availability, capital cost, runoff composition concentrations, and the potential public health risks. Unlike a natural wetland system in which hydrology is largely fixed by the tolerance limits of the existing plant community, a constructed wetland may be designed to regulate water depth and retention time based on the influent quality.

A constructed SF wetland is a shallow, engineered pond (about 30 cm deep) that is planted with local emergent and rooted vegetation. Runoff is introduced at one end and flows across the wetland area to the discharge point. The emergent plants of SF wetlands are not harvested to remove nutrients. Instead, the natural assimilative capacity of the microbial flora (bacteria and fungi) that attach to the plants, provides efficient and reliable removal of biodegradable organics and nitrogen (ammonia and nitrate).

Metals and phosphorus may be sequestered in plant materials and wetland sediments. Most of the treatment is a function of the microbial, physical and chemical action rather than plant uptake; therefore, these processes may occur during cold weather.

SSF wetlands are gravel or organic soil based systems, in which the wastewater substrate passes through the permeable media. The flow is subsurface in and around the roots of the wetland plants.

Flow through the media may also be horizontal flow, referred as subsurface horizontal-flow wetland; or vertically downward, referred as subsurface vertical-flow wetland. The large surface area of the media and the plant roots provides sites for microbial activity, and SSF systems use many of the same emergent plant species as SF systems.

SSF wetland systems have better performance in cold weather because most of the treatment occurs below the ground surface where the treatment processes are less affected by cold air temperatures. In addition, media based systems have relatively low in maintenance requirements and are less likely to have odor and mosquito problems in comparison with SF wetlands. When properly designed, media based wetland systems have high removing efficiency rates for biodegradable organic matter and nitratenitrogen. Another consideration that makes the SSF system attractive is the reduced potential for human contact with partially treated wastewater, which reduces public health concerns.

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There are some general considerations for the design of a constructed wetland, and every wetland system is site-specific and the assistance of an experienced wetland designer is critical to the success of a wetland project. Some key components to consider are: • • • • • • • • •

Available land area Available vegetation Available soil materials Contaminant removal objectives Operating window dictated by freezing conditions Hydraulic retention time (HRT) Gravity flow availability Nuisance controls (i.e. mosquito and odour control) Maintenance and self-sustainability.

To meet the perspective discharge criteria, it is important to design the wetland system with a hydraulic retention time (HRT) sufficient to reduce the organic contaminant and nitrogen concentrations under cold water temperature conditions. This will require additional land area as compared to a system operated with a warmer water temperature. The minimum HRT is 7 to 10 days for SF wetlands and 2 to 4 days for SSF wetlands. Based upon this criterion, the land area required for a SF wetland system will be at least twice as large as a SSF wetland system.

The porous media of SSF wetland will provide more contact area between contaminants and microbes/medium particles. The contaminants will first partition from the liquid phase into the solid phase, and then be absorbed by the plant roots. The SSF wetland systems have a higher removal efficiency for biodegradable organic matter and nitrate-nitrogen than SF wetland system in comparing the areal removal rate constant.

Considering the advantages and disadvantages, and the local conditions in Iqaluit, a SSF wetland system is recommended for Iqaluit landfill surface runoff treatment process.

3. Design Criteria for Wetland System Wetland performance may be characterized by contaminant concentration reduction, by mass reduction or by areal load reduction. There are no guidelines for treated landfill surface runoff in Nunavut. The benchmark conditions on the treated discharge are the discharge limits for Sewage Lagoon effluents of the City of Iqaluit Water Licence.

Suspended solids are principally removed in a wetland system by physical filtration processes.

Subsurface flow (SSF) wetland systems effectively remove suspended solids from contaminated water.

Suspended solids within SSF system may block the pores or bedding media, and as a result, will decrease the hydraulic conductivity or the flow through the system, especially near the inlet. Organic matter is removed in the wetland systems by deposition and filtration for settleable BOD, and by microbial metabolism for soluble BOD. The removal efficiencies for BOD5 vary significantly depending on the organic loading rates, dissolved oxygen concentration, water temperature, bedding media and plant species.

Metals are removed by cation exchange to wetland sediments, precipitation as insoluble salts and plant uptakes. The major concerned metals are Iron, Zinc, Copper, Aluminum and Lead in Iqaluit, based on the 2006 sampling results. The average removals of these metals were reported in the range of 50 to 90%. The reduction of nutrients, nitrogen (N) and phosphorus (P) requires the longest hydraulic retention time of any of the anticipated pollutants. The phosphorus concentration measured in 2006 sampling event was 0.8 mg/L, which is lower than the Canadian Guideline 1.0 mg/L. For most wetland treatment, P is not regarded as an important pollutant; however, P is a required supplement to support biological processes.

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The retention pond provides storage for runoff generated from landfill site during the period of October through May (See Figure 1). It is anticipated that the wetland treatment for the retention pond accumulation will be operated during the frost free period of June through September.

Hydraulic retention time for constructed wetlands is typically in the range of 1 to 10 days. The HRT for the proposed SSF wetland system is 4 days to maximize the removal of the contaminants based on the local conditions.

Hydraulic loading rate is a primary design factor for constructed wetlands. The selection of an appropriate design loading rate should be based on several factors, including treatment objectives, wetland used for levels of treatment, wetland types, and safety factors. Since constructed wetlands technology is a variable science, the facility may be conservatively designed with low loading rates. The average loading rates for wetland treatment of municipal wastewater is approximately 3 cm/day.

Considering the cold climate and runoff parameters at the landfill site, the proposed design hydraulic loading rate is 2.5 cm/day.

4. Conceptual Design of Wetland System The design of the wetland will include the sizing of wetland, a pumping system to pump runoff from the retention pond to the wetland, the plant selection suitable for the local climate and removal of contaminants, bedding materials, and the reduction of suspended materials in the retention pond.

The proposed approach to the facility design is to complete a pilot study to determine the performance of the wetland system. A series of sampling tests will be needed to determine the surface runoff water characteristics in the retention pond and the wetland itself over the duration of the wetland operating 3 3 season. The estimated surface runoff volumes are 7,700 m from November to May and 6,600 m for June to October. Runoff testing to meet the guidelines of NWT, may provide some flexibility in the discharge strategies. The potential total runoff treatment needs for the wetland may be up to 14,300 m3 per year.

The proposed wetland will be a subsurface flow wetland with permeable soil matrix growing medium as discussed in Section 2. Runoff will be introduced via perforated head pipe to a gravel flow dispersion trench (See Figure 2). Runoff will permeate through the side of the flow spreader trench, through a peat bed, then into the permeable medium. The sacrificial peat bed will buffer the wetland against spike concentrations of contaminants. Since there is a slope from the inlet to the discharge point of the proposed wetland area, the SSF will be designed as a horizontal subsurface flow. The design slope will be calculated based on the anticipated hydraulic conductivity of available materials for the bedding media.

At the outlet of the wetland, another gravel trench will be placed with a perforated pipe. The treated runoff may then be discharged to a stream on the northeast corner of proposed SSF wetland.

The ability of wetlands to remove contaminants from water relies on the emergent plants, which play a key role in a wetland treatment process. Plants provide an oxygen source to help sustain aerobic conditions in the wetland, and plant roots provide passages for water to filtrate through the bedding media.

As water slowly flows through a wetland, pollutants are removed through physical, chemical, and biological processes. The physical processes include entrapment, sedimentation and adsorption. The biological processes include nitrification and denitrification, the uptake of nutrients and metals by plants, and by organisms that occupy on the bedding media. The different species of organisms and plants may have markedly different success depending on factors such as type and toxicity of individual pollutant, water level and temperature.

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The performance of a constructed wetland for contaminant removal often depends on the proper interaction among hydraulic retention time (HRT) and flow, contaminant compositions, vegetation and seasonal temperatures. It is difficult to determine the exact area needed for effective treatment of runoff since specific hydraulic and pollution fluctuations, as well as varying local climatic conditions have to be taken into consideration. There are two methods to estimate the preliminary area for the constructed wetland. One method is to use the model based on reaction kinetics; the other method is to calculate the land area required using the selected hydraulic loading rate.

The reaction kinetics model to determine the preliminary area requirements is based on desired effluent quality, first areal rate constants and background limits of the contaminants. To achieve a conservative estimate of land area required, modeling was conducted on BOD and TSS. The other factors can be used in modeling are TP, TN, ammonia, and organic nitrogen. However, the sampling programs conducted in 2004 and 2006 show that the results of these parameters are below the guidelines of NWT, 1992. The land area calculated is 840 m2 to meet the BOD discharge guideline 120 mg/L. Should the BOD discharge concentration be 45 mg/L (as in 2005 Yukon Interim), the area required is 2,070 m2.

The hydraulic loading rate is assumed to be 2.5 cm/day (0.025 m3/m2/day) for optimal removal efficiency (as discussed in Section 3). Therefore, the area estimated for surface runoff treatment during an average 105 frost free days, to treat 7,700 m3 of surface runoff, is approximately 2,940 m2.

Comparing the reaction model method with hydraulic loading rate method, the difference for the calculated land area to treat the same runoff volume is significant. The calculated land area by the reaction model method is the area required to treat BOD to meet the effluent guidelines, BOD is the governing parameter based upon its larger area requirement.

The rate constant and temperature coefficient in the calculation are based on the broad range of study results, not specifically for the cold climate. Therefore, these parameters may not represent the actual biochemical reaction and rate constants in the proposed wetland system, particularly the temperature coefficient, θ.

The land area requirement calculated from hydraulic loading rate is much larger than the land area calculated from the reaction model. In order to be conservative, the larger land area requirements will be applied to the proposed wetland system during the conceptual design. The pilot study results will allow for an optimization of the wetland system based upon the local conditions.

5. Recommendation and Implementation Iqaluit may develop the wetland system for the treatment of landfill on-site surface runoff. It was recommended that the subsurface flow wetland system be designed to treat the surface runoff from the landfill site of Iqaluit. During the pilot operation, by collecting the water quality parameters of the wetland influent and discharge, the operation of the wetland treatment system will be monitored and evaluated for the need to expand the system.

The conceptual design for Iqaluit West 40 Landfill site surface runoff provides a practical and valuable solution for the management and protection of water bodies surround the landfill site. Following the recommendations made within this report, the next steps are: 1.

2.

3.

4.

5.

6.

Submission of the conceptual design for regulator review; Monitoring the quality of runoff contained in control ponds and the retention pond; Completion of preliminary engineering for the pilot program for the proposed wetland treatment; Completion of detailed design and tendering for construction; Operating the facility and monitoring performance; Planning for facility optimization based on performance.

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6. References Alberta Environment (AE). Guidelines for the Approval and Design of Natural and Constructed Treatment Wetlands for Water Quality Improvement. March 2003.

Donald A. Hammer. Constructed Wetlands for Wastewater Treatment: Municipal, Industrial and Agricultural. Lewis Publisher, Michigan, 1990.

George Mulamoottil, Edward A. McBean and Frank Rovers. Constructed Wetlands for the Treatment of Landfill Leachates. Lewis Publishers, New York, 1999.

Ken Johnson, Role of Saturated and Unsaturated Zones in Soil Disposal of Septic Tank Effluent. Master of Applied Science Thesis, University of British Columbia, 1986.

Keith D. Johnson, Craig D. Martin, Gerald A. Moshiri, and Willian C. McCrory. Performance of a Constructed Wetland Leachate Treatment System at the Chunchula Landfill, Mobil County, Alabama.

Lewis Publishers, New York, 1999.

MACA, NWT. The Guidelines for the Discharge of Treated Municipal Wastewater in the Northwest Territories, 1992.

Nunavut Water Board Water Licence: City of Iqaluit, No.3AM-IQA0611 TYPE “A”, issued by Indian and Northern Affair Canada, 2006.

R.H. Kadlec and R.L. Knight. Treatment Wetlands. Lewis Publishers Co. 1996.

R.H. Kadlec. Constructed Wetlands for Treating Landfill Leachate. In Chapter 2 of “Constructed Wetland for the Treatment of Landfill Leachates,” edited by George Mulamoottil, Edward A. McBean and Frank Rovers. Lewis Publishers, New York, 1999.

United States Environmental Protection Agency (USEPA). Design Manual: Constructed Wetlands and Aquatic Plant Systems for Municipal Wastewater Treatment. EPA 625-1-88-022. U.S. EPA Office of Research and Development, Center for Environmental Research Information. Cincinnati, OH, 1988.

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Water and Sewer Systems Serving Dawson City, Yukon Norm Carlson, Public Works Manager, Dawson City, YT Ken Johnson, Senior Engineer and Planner, Earth Tech, Edmonton, AB July 2007 Introduction Dawson City, Yukon Territory is a community of approximately 1,500 people, located in the mid-western section of the Territory, in an area of discontinuous permafrost. The Town’s water and sewer services are provided by a buried insulated high density polyethylene pipe (HDPE) utility system which was completed around 1980. The water and sewer infrastructure is reasonably complex in both its construction and operation; the operation alone requires a dedicated staff of 5 individuals.

The date of construction of the first components of the Dawson City water and sewer system is not known precisely, however, it has been recorded that Dawson had a water and sewer system in operation as early as 1904. A description of the system operation in 1911 states that "only three or four houses in Dawson were equipped with year-round running water. To prevent their freezing in winter, the water pipes had to be linked to parallel pipes of live steam which must be kept constantly hot. In addition, the water must be kept moving through the pipes continually, and thence through an insulated outlet all the way to the river.” The original pipe installations were wood stave construction, and this piping continued to be used until the 1970’s (See Figure 1).

Beyond the piping systems that are associated with the infrastructure, there are 12 facilities that are an integral part of the infrastructure. The facilities handle approximately 850,000 cubic metres (190 million Imperial gallons) each of water and sewage in a year (2005 estimate).

Dawson Water System Dawson City’s water system facilities consist of the water source, the water storage, and the water treatment and distribution. The water source is a series of three wells located along the river bank, near the junction of the Klondike and Yukon Rivers (See Figure 2), drilled to depths of approximately 23 metres (80 feet). One original well was installed in 1959, and three additional wells were installed in 1991 to provide additional capacity. The newer wells are situated in concrete access vaults with an adjacent well control building. The original well is situated in a wooden building, and is generally used only as an emergency back up supply.

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The water storage consists of two insulated steel reservoirs beside the water treatment and distribution building (See Figure 3). The two reservoirs have a combined storage of approximate 1300 cubic metres (290,000 Imperial gallons), which provides storage for drinking water supply and fire protection.

The water treatment and distribution consists of a building which contains various chemical, heating, pumping, electrical and piping systems for water treatment, freeze protection for the system, and water distribution. The water treatment consists of controlled chlorine gas injection into the water prior to distribution into the buried water system.

Freeze protection for the water system is needed during the winter; the water in the pipes cools as it flows through the distribution piping, therefore additional heat is required to prevent the water in the pipes from freezing.

The water is also recirculated by pumping to confirm the water temperature in the pipe, and provide additional freeze protection – on-line hydrants are a feature of this type of recirculating system (See Figure 4). The water distribution system itself consists of 16 kilometres (10 miles) of insulated, buried HDPE water main. The distribution system includes approximately 700 service connections to buildings and 85 fire hydrants. The system also includes a valve chamber building for controlling the flow of water.

Dawson Sewage System Dawson City’s sewage system facilities consist of the five lift stations, and the sewage treatment plant. The sewage collection system itself consists of 16 kilometres (10 miles) of insulated, buried sanitary sewer, and approximately 3.5 kilometres (2 miles) of buried forcemain from the lift stations. The sewage lift stations generally consist of submersible pumping systems in wetwells, with control buildings either on top of or adjacent to the wet wells. Four of the lift stations may be considered “small” facilities, and the remaining facility may be considered a medium sized facility. Four of the lift stations collect sewage from the developments along the Klondike Highway along the access highway into Dawson City.

The sewage treatment facility consists of a primary screening operation using two 0.75 millimetre mesh rotostrainers housed in a multi level building (See Figure 5). The sewage discharges into the Yukon River, mid-channel 200 metres (650 feet) west of perimeter dyke that surrounds the community.

Challenges of Dawson City Water and Sewage System Subsoil conditions in Dawson City typically consist of a surface layer of common road fill 0.6 to 0.9 metres in thickness, underlain by organics, organic silts, and silts to a depth of 3 to 5 metres. This layer of silt and organic silt has

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an ice content varying from zero to greater than 50 percent excess ice content. Beneath this layer of organic silt, a layer of alluvial gravels has been deposited by the Yukon River; these gravels are relatively dense and thaw stable.

This area is in the widespread discontinuous permafrost zone, with mean ground temperatures in the range of -1.5 C, which is considered to be “warm” permafrost. Since the permafrost temperature is just below freezing, the permafrost may thaw or degrade very easily from disturbances such as the installation of underground utilities. Problems with respect to water and sewer systems in these soil conditions have caused ground subsidence due to thaw of the ice rich permafrost, seasonal frost heave of buried foundations and utility pipes, or groundwater conditions. In a two year period, in the mid 1980’s over 225 metres of polyethylene sewer pipe failed by ovalling or collapsing.

The problems due to frost action in the soils were compounded in the vicinity of hydrants, vertical risers and service connections because a vertical restraint is imposed on the piping system. At service connection locations, there were numerous examples of service risers causing a local collapse of the main because of the vertical load on the horizontal sewer main.

Adjacent to hydrants and valves, pipe failures occurred at fusion weld joints because of bending or torque along the connecting pipe.

The unique soil conditions in Dawson City has required the development of unique water and sewer piping materials and installation techniques. Several studies in the late 1980’s compared pipe and bedding configurations, and developed the corrugated cover on insulated HDPE piping that is the pipe standard for Dawson City today (See Figures 6). The installation of the pipe requires consideration of the permafrost conditions to ensure that the area around the excavation is not significantly disturbed, particularly in areas where the permafrost has a lot of ice lensing.

Future Water and Sewer Improvements Dawson City continues to incrementally address the challenges of operating and maintaining a water and sewer facilities in the heart of Klondike. Bleeder reduction has been a priority over the past several years and water metering has been implemented to reduce water down in the range of 500 litres/capital/day from winter extremes of 1500 litres/capita/day. A comprehensive water and sewer facility assessment was completed in 2006, which has provided Dawson with the framework for system improvements over the next 20 years.

The most significant initiative has been the replacement of the preliminary treatment system with an aerated lagoon treatment system, which is scheduled for completion in 2010.

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Photo 2

Photo 1 Photo 3

Photo 4

Figure 5

Figure 6

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The 2006 Annual General Conference of the Canadian Society for Civil Engineering 2006 Congrès général annuel de la Société canadienne de génie civil

Calgary, Alberta, Canada May 23-26, 2006 / 23-26 Mai 2006

Application Of Large Scale At-Grade Sewage Treatment And Disposal In Fort Good Hope, NWT Kenneth R. Johnson1, Amir Agha2, and Mukesh Mathrani1 1 Earth Tech Canada Inc., Edmonton, Alberta, Canada 2 Department of Municipal and Community Affairs, GNWT, Norman Wells, NWT, Canada Abstract: The Charter Community of Fort Good Hope, NWT continues to use an exfiltration trench for disposal and treatment of domestic wastewater. This community of 550 people is located just south of the Arctic Circle, in the continuous permafrost region of the north. Sewage volumes are expected to increase with the community population over the next twenty years, and the existing exfiltration lagoon configuration will ultimately not have the capacity for the increasing volume. A study was completed to evaluate the capacity and efficiency of the existing system, and the opportunity to maintain, or improve this unusual application of at-grade sewage treatment and disposal. Based upon the available site information and the performance of the existing system, it was concluded that the process has the hydraulic and treatment capacity to meet the community’s demand and maintain regulatory compliance.

1.

1.1

INTRODUCTION Community Environment

The Charter Community of Fort Good Hope (K'asho Got'ine) is a Dene community in the Sahtu Region of the Northwest Territories, located at 66º 15' N and 128º 3' W. The community lies on a peninsula at the confluence of Jackfish Creek, and the east bank of the Mackenzie River (See Figure 1). The town site is 27 kilometres south of the Arctic Circle, about 805 kilometres northwest by air from Yellowknife, and 145 kilometres northwest of Norman Wells.

The terrain surrounding Fort Good Hope generally consists of muskeg, swamp, and areas covered with trees ranging in size from stunted growth up to 12 metres in height. However, several significant glacial and fluvial deposits surround the community, and provide one of the few nearby community deposits of concrete gravel in the NWT. Fort Good Hope is situated within the continuous permafrost zone; the active layer penetrates 0.5 to 1.2 metres below the ground surface in the summer.

The community receives a total annual precipitation of 267 millimetres, with an average of 150 millimetres of rain and 132 centimetres of snow each year. Mean high and low temperatures vary between 22.6 and 9.9ºC in July and between -27.5 and -35.0ºC in January. Prevailing winds are from the east and average 9.5 km/h annually.

Sewage collection in Fort Good Hope employs sewage pumpout tanks. Pumped out sewage is trucked to an exfiltration trench located at the waste disposal facility about 3.5 kilometres north of the community.

The estimated monthly volume of pumpout sewage discharged to the exfiltration trench is 1.6 million litres, which is approximately 140 litres per capita per day (550 estimated population). The exfiltration trench is GC-###--1 157

approximately 98 metres long, 12 metre wide and up to 3 metres deep; the approximate working volume of the trench is 1500 cubic metres.

Figure 1. Fort Good Hope site plan.

1.2

Existing Sewage Exfiltration Area

The 9.0 hectare waste disposal site (240 metres wide by 375 metres long), and is part of a 90 hectare glacial outwash plain located between the townsite and the Hare Indian River. The average depth of the glacial outwash plain is approximately 10 metres, and the deposit contains approximately 9 million cubic metres of poorly graded gravel. The glacial out wash place is one of a series of granular deposits around Fort Good Hope.

The deposit is comprised of medium grained gravel that ranges in soil classification from "poorly graded gravel, gravel-sand mix, little or no fines" to "poorly graded sand, gravelly sand, little or no fines". The gradation of the gravel in the area ranges between 20% and 95% sand, 2% and 7 9% gravel, and 1% to 14% silt-clay. The high permeability of the gravel results in good drainage within the area, and the water table in this area appears to be deeper than 15 metres, while the depth of the sewage trench is up to 3 metres deep.

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The exfiltration trench does not have any "controlled" discharge system. Upon discharge into the trench, the sewage flows by gravity to fill the entire trench to a level surface. The sewage then "exfiltrates" from the bottom and sides of the trench into the glacial outwash plain deposit, and then "percolates" downward through the deposit (unsaturated flow) until the groundwater table, and then flows into the groundwater (saturated flow).

The exfiltration trench in the glacial outwash plain is situated at an elevation of approximately 230 metres, which is about 225 metres above the Mackenzie River elevation of 75 metres (See Figure 2). The exfiltration trench is about 1200 metres from the Mackenzie River. The exfiltration trench and the outwash plain are both oriented parallel to the Mackenzie River.

2.

SYSTEM OPERATION AND PERFORMANCE

The Water Licence issued to the Charter Community of Fort Good Hope by the Sahtu Land and Water Board refers to an appended "Surveillance Network Program" (SNP) when outlining the effluent quality standards required for compliance of the sewage trench seepage. However, the SNP information does not include any specific discharge criteria; historically, many northern communities have been required to meet the discharge parameters of effluent 120 mg/L for Biological Oxygen Demand (BOD5), and 180 mg/L for effluent Total Suspended Solids (TSS).

The exfiltration trench treats the sewage in a much different way than the more conventional sewage retention lagoon. A retention lagoon uses the elements of nature at the earth's surface including heat, sunlight, wind and surface vegetation. An exfiltration trench uses the elements of nature in the available soil "matrix", and the processes of biodegradation, filtration, adsorption and absorption to remove the contaminants in sewage.

The trench is currently capable of accommodating the volume of sewage produced by Fort Good Hope based upon the community observations; in fact, the sewage percolates quickly into the gravel. However, the community has observed that the level of liquid in the trench has been steadily increasing with time, which is an anticipated part of the performance of an exfiltration process. Sewage solids accumulate with time over the bottom of the trench, and reduce the permeability of the soil; at the same time, this reduction in permeability also reduces the flow through the soil, and enhances the processes removing the contaminants in the soil.

Sampling was performed in the months of June to August 2001 on the seepage that is believed to originate from the sewage exfiltration trench. The samples were taken from a stream of water between the exfiltration trench and the Mackenzie River, with the assumption that the groundwater flows toward the Mackenzie River. The results of the sampling analyses indicated that the BOD5 ranged from less than 2 to 7 mg/L, and that the TSS ranged from less than 3 to 6 mg/L. This limited sample data indicates a very high quality of effluent treatment within the soil matrix beneath the exfiltration trench; this effluent quality may be equated to a tertiary level of treatment.

In comparison the commonly used water effluent parameters in northern community water licenses, as discussed previously, the BOD5 measured at Fort Good Hope is well below the target of 120 mg/L and the TSS analyzed was well below 180 mg/L.

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Figure 2. Fort Good Hope site plan and profile.

3.

WASTE GENERATION AND SYSTEM CAPACITIES

The production of sewage in Fort Good Hope is expected to increase substantially in the next 20 years.

Statistics from the Government of the Northwest Territories projects that aboriginal populations may increase at a rate of 0.5 % annually. Based on the estimated population of Fort Good Hope in the year 2003 of 550, and a water consumption volume of 140 litres (0.140 m3) per person per day (April 2004), an estimated 25,000 m3 of domestic sewage will be produced annually by the year 2015, and 32,000 m3 by the year 2025.

The existing exfiltration trench has never overflowed, however, the community is concerned that the trench is filling up higher than it ever has before and could overflow in the near future. The ultimate capacity of the existing system is impossible to calculate given the many factors that influence the hydraulic capacity GC-###--4 160

of the trench. These factors include the granular material in the base and side of the trench, the solids accumulation in the base and sides of the trench, the influence of seasonal frost in reducing the soil permeability, and the influence of permafrost on the soil permeability. The best indication of system capacity are site observations on the rate of exfiltration from the trench; this activity is essentially a "percolation test" of the soil.

From a design perspective, the general operational range or hydraulic loading for a "rapid infiltration" system such as this is 6 to 125 metres per year. The estimated loading rate of the Fort Good Hope 3 exfiltration trench is about 20 metres per year based upon sewage generation of 50 m per day, and an 2 estimated infiltration surface of 900 m .

4.

SOIL EXFILTRATION TREATMENT PROCESSES

Soil exfiltration of wastewater uses the elements of nature in the available soil "matrix", and the processes of biodegradation, filtration, adsorption and absorption to remove the contaminants in sewage. A soil matrix approximately 30 centimetres (12 inches) thick may adequately remove the contaminants in sewage, if it is appropriately engineered and operated. All soils have a natural capability to "filter" contaminants because of the inherent biology, and chemical activities that occur in soil.

A soil exfiltration system may produce a tertiary quality effluent if engineered and operated properly. The anticipated effluent characteristics are presented in Table 1.

Table 1. Anticipated Effluent Characteristics Effluent Parameter BOD5 TSS Total Nitrogen Total Phosphorous Fecal Coliforms

< 5 mg/L < 2 mg/L < 10 mg/L < 1 mg/L < 10 FC/100 mL

The wastewater contaminants that have been most widely studied for removal by a soil matrix are coliforms, biodegradable material (measured by BOD5), nitrogen and phosphorous. Coliforms and other pathogen organisms are removed by physical straining, and "die off" as a result of the harsh environment of the soil. This harsh environment includes the temperature, the absence of any nutrients for the coliforms, and the natural antibiotics in the soil.

Biodegradable material is removed by the bacterial metabolism with the "living filter" of the soil â&#x20AC;&#x201C; the natural or introduced bacterial literally consume the biodegradable material as it flows through the soil.

Nitrogen compounds, primarily in the form of ammonia, undergo a series of reactions with a soil profile resulting in the transformation, and potentially the complete removal of nitrogen from the soil or the storage of nitrogen in the soil. From a biochemical and chemical perspective, the nitrogen removal occurs as a result of nitrification, denitrification, volatization or chemodenitrification. Within a gravel soil profile the nitrogen transformation may be limited to nitrification and the formation of nitrates, which may occur to an extent of 80% within a 1 metre depth of soil. Phosphorous compounds are "retained" by soil through either a chemical reaction or an adsorption reaction.

In the application of these "processes" in the natural environment, there is a recognition that the process occurs at different rates in "unsaturated" and "saturated" zones in the soil (See Figure 3). The saturated and unsaturated zones are defined by the position of the groundwater table â&#x20AC;&#x201C; the unsaturated zone is the region above the groundwater table and the saturated zone is in the region below the groundwater table.

The efficiency and rate of the various biochemical and chemical processes is substantially higher in the unsaturated zone, and this fact is recognized in most regulations governing the use of soil for effluent disposal, where a minimum unsaturated depth of soil is required for complete treatment to occur. These GC-###--5 161

depths vary from as little as 30 centimetres for well graded sand to about 1 metre for other soil types.

However, the saturated zone still has "treatment" capabilities that are significant.

Temperature may have a significant influence on the biochemical and chemical processes within the soil; however, biochemical and chemical process still occur at cold temperatures, but at slower rates. In practical terms, slower rates demand either a lower sewage application on a given soil profile, or an increased soil profile to achieve the same level of treatment.

Figure 3. Soil exfiltration treatment processes.

5.

CONCLUSIONS AND RECOMMENDATIONS

The existing sewage exfiltration trench in Charter Community Fort Good Hope is an appropriate sewage treatment technology for this community based upon the technical process information, and the limited performance data. The process is capable of providing a very high quality sewage effluent before discharge into the receiving environment.

A number of improvements may be made to the existing process, both in the construction and the operation and maintenance. The capital improvements include: 1. Constructing an erosion protected discharge into the trench to reduce the accumulation of rocks and sediment in the trench.

2. Constructing an engineered discharge structure beside the trench.

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3. Constructing a perimeter fence to isolate the trench.

4. Constructing a water level monitoring post in the trench.

The operation and maintenance improvements include: 1. Undertaking regular sampling of the representative discharge from the trench at the base of the granular deposit.

2. Undertaking regular monitoring of the water level in the trench.

3. Undertaking periodic “resting” of the trenches (summer only), where a second trench is needed to meet the treatment capacity for the community.

The capacity limitation of the existing trench is difficult to determine, therefore the regular monitoring of the water level will provide the necessary data to determine the timeframe for increasing the capacity of the sewage exfiltration system. When a second trench is required, it should be constructed beyond the existing trench, and not parallel to the existing trench, in order to take advantage of additional treatment capacity in the granular deposit.

The design criteria for the trench should include a long narrow excavation with a minimum depth of 3 metres in order to minimize the surface area exposed to the atmosphere, and to maximize the heat retention.

6.

REFERENCES

Dillon Consulting Limited. 2003. Fort Good Hope Water Licence Application.

Ferguson Simek Clark. 2000. Draft Report: Engineering and Environmental Services Fort Good Hope – Sewage and Solid Waste Assessment.

Ferguson Simek Clark. 2000. Sewage and Solid Waste Management Site Operations and Maintenance Manual.

Johnson, Kenneth Robert. 1986. Role of Saturated and Unsaturated Zones in Soil Disposal of Septic Tank Effluent.

Johnson, Ken and Wilson, Anne. 1999. Sewage Treatment Systems in Communities and Camps of the Northwest Territories and Nunavut Territory. Proceedings of the 1st Cold Regions Specialty Conference of the Canadian Society for Civil Engineering.

K’asho Got’ine Chartered Community Council. 2005. Annual Report for Water.

Reed, S.C., Crites, R.W., and Middlebrooks, E.J.1995. Natural Systems for Waste Management and Treatment.

Terriplan Consultants Ltd. and Ferguson Simek Clark. 2001.

Zoning By-Law Background Report.

Fort Good Hope Community Plan and

Thurber Engineering Ltd. 1995. Granular Inventory and Management Plan – Community of Fort Good Hope, NWT.

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Integrated Waste Management in Iqaluit, Nunavut Ken Johnson, P.Eng., Earth Tech Canada Glenn Prosko, P.Eng., Earth Tech Canada Prepared for Consulting Engineers of Award Application, September, 2006 Received Award of Merit, Municipal Engineering Category Background Since the application of modern sewage treatment technologies in the past century, municipal sewage sludge has been an inherent part of overall waste management practices.

It was traditionally considered a waste product, and disposed of like any other waste.

Ultimately, however, the high nutrient characteristics and pathogens in sewage sludge were identified, and over the past 30 years sewage sludge has been recognized as a waste material that requires specific handling, treatment and disposal practices.

Sewage sludge also has beneficial uses which have been covered by government regulations since the early 1990’s. These regulations discourage the disposal of untreated sewage sludge on agriculture lands or in landfills. Most municipalities in Canada recognize that sewage sludge presents treatment and disposal challenges, and that care is needed to protect public health and the environment.

In the Canadian north, municipal sewage sludge has been virtually ignored because of the predominance of lagoon wastewater treatment systems. In a lagoon system, sewage sludge essentially becomes part of the lagoon itself as it settles to the bottom. Only when the performance of a lagoon starts to decrease substantially is it deemed necessary to remove sewage sludge. This periodic exercise may occur every 10 to 15 years.

The application of mechanical sewage treatment systems in the Northwest Territories and Nunavut, and an increased regulatory scrutiny over the past 15 years have created a demand for sewage sludge handling, treatment, and disposal. Landfilling of sewage sludge is a “tried and true” technology because of its limited requirements for planning, engineering and regulation; however, regulatory demands have been increasing, and sludge management in an engineered context is a necessary part of any new mechanical sewage treatment system.

The City of Iqaluit, Nunavut has been working toward the implementation of a secondary sewage treatment system since 1998. This is an ambitious goal for the community considering the inherent challenges to the design, construction and operation of facilities in the harsh arctic environment.

After an initial membrane treatment project failed to be commissioned in 2000, the City Figure 1: Trucked Sewage Discharge Iqaluit WWTP Phase 1 in background

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Integrated Waste Management in Iqaluit, Nunavut chose to pursue a conventional activated sludge process: the first phase (primary treatment) of this project was commissioned in May 2006; the second phase (secondary treatment) is scheduled for implementation within the next 5 years.

Community Characteristics Iqaluit is the largest community and the capital city of Nunavut, located in the southeast part of the Baffin Island, at 63° 44’ N latitude and 68° 31’ W longitude. Iqaluit is 2300 kilometres east of Yellowknife, and 2800 kilometres northeast of Edmonton. Located at the head of Frobisher Bay, the community was established in 1949 as the community of Frobisher Bay. It became a municipal hamlet in 1971 and the capital city of Nunavut in 1999. The Government of Nunavut population projection for Iqaluit was 5,600 in 2005 and the community is expected to grow to Figure 2: Iqaluit WWTP Phase 1 over 8,000 in the year 2020. Approximately 60 percent of the community is presently aboriginal. Land area within the municipal boundary is 52.3 square kilometres.

Iqaluit’s location is above the tree line and within the continuous permafrost zone of Canada. The terrain surrounding Iqaluit is “rolling”, and the region generally consists of glacially scoured igneous/metamorphic terrain. The overburden consists of silty-sand, sand, gravel and boulders, which varies in depth up to 18 meters. For 8 months of the year, the average daily temperature in Iqaluit is below freezing. The January high and low mean temperatures are -21.5 °C and -29.7 °C, respectively, and the July high and low mean temperatures are 11.4 °C and 3.7 °C, respectively. Annual precipitation is 43.0 cm, and is made up of 19.2 cm of rainfall and 25.5 cm of snowfall.

The community operates both a piped sewage system and a trucked sewage system. The pipe sewage system serves approximately 65 percent of the community, and the remainder of community is served by trucks which pumpout individual tanks in each home.

Solid Waste Management Practices The City produces approximately 10,000 cubic meters of compacted waste, which enters the landfill each year, and includes residential, commercial and industrial wastes. Recycling is currently limited to the collection and diversion of aluminum cans. The City’s landfill operation uses the area method, which involves placing waste above grade against a berm, compacting the waste using a wheeled loader, and covering the waste using a mulch material.

The waste is covered once per day during the summer and once per week during the winter.

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Integrated Waste Management in Iqaluit, Nunavut

Figure 3: Iqaluit Landfill

City of Iqaluit landfill staff have taken significant steps in attempting to reduce the amount of waste entering the existing operational cell. Shredding the waste was identified as a significant volume reduction measure, as the resulting mulch may be used as a waste cover material. The amount of waste deposited at the Cityâ&#x20AC;&#x2122;s landfill which is available for reuse as cover material is approximately 20% of the total annual volume. This waste for reuse consists mainly of select construction debris, furniture, cardboard and plastic. The waste is segregated from the general waste stream and stockpiled in a specific area of the landfill.

Limited compaction is then used to prepare the waste material for loading in the 120 hp shredder.

Figure 4: Shredder Operation at Iqaluit Landfill Raw material on left and finished product on right

Once these materials have been properly shredded, the material is stockpiled and used for landfill cover, local road building (within landfill), and berm reinforcement during the winter months.

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Integrated Waste Management in Iqaluit, Nunavut Sewage Sludge Composition and Volumes The sewage sludge waste streams from the wastewater treatment plant (WWTP) will have 3 distinct components: the first will be fine screening, the second will be sludge from the primary filter, and the third will be sludge from the waste activated treatment system.

The first phase of the WWTP project will incorporate only sludge streams for fine screening and the primary filter. The fine screening is accomplished utilizing screens salvaged from the original un-commissioned construction; the primary sludge is produced form a newly installed Salsnes filter. The Salsnes filter is a relatively new process with its origins in Norway, which applies a moving fabric with a nominal opening size of 300 microns to filter the sewage. The daily mass of screenings and primary sewage sludge produced from a future population of over 8,000 (in the year 2020) is Figure 5: Phase 1 Filtration expected to be approximately 1,700 kilogram (a volume Systems - Fine Screen and of approximately 1.8 to 2.0 cubic meters). With these Primary Filter quantities, the primary sewage sludge trailer would have to be unloaded once every two days. With the current population of 5,600, the sludge trailer is unloaded every two or three days.

Figure 6: Sludge from Primary Filter (Salsnes filtration unit)

Figure 7: Sewage Sludge Trailer

Environmental Planning for Sludge Management The potential land base available to the City of Iqaluit is very large at over 50 square kilometers, particularly in comparison to the population base of approximately 6,000 people.

However, the potential area for sewage sludge management is very limited by the existing road network. Building any new access road is very expensive, with a capital cost in excess of $500,000 per kilometer in addition to significant operation and maintenance costs.

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Integrated Waste Management in Iqaluit, Nunavut

Figure 8: Development Setback Envelope for Waste Management

Figure 9: Land Use in and around Iqaluit

One of the primary regulations governing the development of any waste management site is a 450 metres setback from residential or commercial developments. Based on the current development limits of the City, a 450 meter setback creates a significant limitation on sludge management.

The City of Iqaluit has a comprehensive community plan which stipulates land use designations and identifies existing land uses of interest or concern to future land development. Of particular interest and concern are the open space areas, and a significant number of old waste disposal sites.

Applying the environment planning information produced three potential locations for potential sludge disposal locations.

Transportation from the WWTP to two of the sites posed a potential concern because the access routes go through the community.

Based on the environmental planning exercise, the existing landfill site was recommended for sludge management.

Figure 10: Three Potential Locations for Sludge Management Sites.

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Integrated Waste Management in Iqaluit, Nunavut Process Review for Sludge Treatment and Disposal Conventional municipal sewage treatment uses physical, chemical, and biological processes to separate solids and biological contaminants from municipal wastewater. Solids in the wastewater are removed through primary treatment (primary sludge), and biological contaminants are removed through secondary treatment (secondary sludge). Solids in the sludge are typically processed in a digester system, in which biodegradable materials are â&#x20AC;&#x153;digestedâ&#x20AC;? into stable organic matter.

Sewage sludge may be further treated through dewatering, heat drying, alkaline (lime) stabilization, composting, or other processes. Regardless of the treatment technology, there are limited options for end use or ultimate disposal of sewage sludge, especially in a harsh arctic environment. . In Canada, approximately 388,700 dry tonnes of biosolids are produced every year. About 43% of the sewage sludge is applied to land, 47% is incinerated, and 4% is sent to landfill, with the remainder used in land reclamation and other uses. Land application has been increasing in recent years as many municipalities move away from incineration and landfill disposal due to environmental concerns with these processes.

There are a variety of conventional as well as modified, patented, and proprietary sewage sludge management technologies available, and many of these technologies are not necessarily "appropriate" for the City of Iqaluit given the extreme operating conditions inherent the climate and location of the community. A comprehensive process was applied to provide a sewage sludge management plan to the City of Iqaluit. The process involved the following steps: 1. Identifying all available sewage sludge management technologies.

2. Establishing and applying screening criteria to all available sewage sludge management technologies to produce a short list for detailed evaluation.

Figure 11: Sewage Sludge

3. Establishing and applying Freeze-Thaw Drying detailed evaluation criteria to screened/short listed sewage sludge management technologies to determine the preferred technology.

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Integrated Waste Management in Iqaluit, Nunavut 4. Reviewing preferred sewage sludge management technologies in the northern context.

5. Recommending the “most appropriate” sewage sludge management technologies.

6. Developing means of implementing recommended (or most appropriate) sewage sludge management technologies.

Additional research of the published literature on “air drying” in cold climates suggested that a “freeze thaw” process may provide an optimization consistent with the cold climate of Iqaluit. The particular climate “attributes” of Iqaluit are: 1. Extreme winter cold, with a record low of -46°C in February 1967.

2. Moderate summer warm, with a record high of +26°C in July 2001.

3. Limited moisture, with an average rainfall of 200 mm per year.

Freezing and thawing, as an efficient method of sewage sludge conditioning, has been used for many years in cold climates. An important aspect of this process is that the separation of sludge particles and water is generally irreversible. The final separation is achieved when the “released” water drains away from the solids after thawing, leaving a porous sludge with solids content of 20 to 30%.

Following this dewatering and drying process, composting may provide stabilization and destruction of pathogens. The composting process will require the addition of bulking materials such as wood chips and cardboard pieces.

Composting of Sewage Biosolids The City of Iqaluit landfill facility has been able to divert sewage biosolids from the first phase of the WWTP. The process plan for the biosolids is to dry the solids throughout the long winter making use of Iqaluit’s cold dry weather, and compost the dried solids during the short warm summers to produce a cover material for the landfill. This process is attractive because the finished material will be non-hazardous and will reduce the use of precious granular material at the landfill - granular material may cost close to $40 per cubic metre in Iqaluit.

The timeline for freeze-thaw-composting will be a two-year cycle: freezing will occur from September to May; thawing from May to June; and composting from June to September.

The compost would then “mature” from September to May, with the total process taking 20 months from start to finish.

This innovation follows in the steps of groundbreaking work by the Bill MacKenzie Humanitarian Society, which proved that composting is feasible in Iqaluit. The innovation captured the attention of the Federation of Canadian Municipalities, which approved a grant application from the City for equipment and testing.

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Integrated Waste Management in Iqaluit, Nunavut

Figure 12: Composting of Household Organics Material in Iqaluit

Compatibility of Sludge Management with Improvements to Landfill In 2006 a major expansion of the City landfill was completed. Sludge management was a significant part of the expansion with a dedicated area developed for sludge freeze-thawcomposting. Overall improvements included on-site and off-site drainage management, and fencing to essentially double the operating footprint of the landfill, providing sufficient capacity through the year 2011.

Although the landfill site has a finite capacity, the integrated waste management approach by the City of Iqaluit has provided the means to divert the biosolids waste stream from the landfill and create a product useful to the ultimate decommissioning of the landfill site.

Managing sewage sludge through freeze-thaw-composting is not without its challenges, but the City of Iqaluit, through its progressive management of its utilities, is succeeding.

Where other municipalities take for granted the technologies available to them, the arctic must re-engineer the process to suit the environment.

Figure 13: Sludge Freeze-Thaw-Composting Area of Landfill Expansion

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The 2006 Annual General Conference of the Canadian Society for Civil Engineering 2006 Congrès général annuel de la Société canadienne de génie civil

Calgary, Alberta, Canada May 23-26, 2006 / 23-26 Mai 2006

Design and Winter Construction of Sewage Lagoon Discharge Pipeline in Landslide Area Near Fort Smith, NWT Kenneth R. Johnson Earth Tech Canada Inc., Edmonton, Alberta, Canada

Abstract: The Town of Fort Smith, Northwest is situated on the bank of the Slave River on the 60th parallel. This community of 2500 people serves as the administrative centre for the Fort Smith Region of the Northwest Territories. The banks of the Slave River are prone to landslides, the most serious of which occurred in 1968, and caused the death of one individual, and the abandonment of a portion of the community. Another significant landslide occurred in August 2004, covering about 500 metres along the river bank, and destroying the community’s sewage discharge pipeline. Resources were immediately mobilized to start the process of replacing the discharge pipeline. These resources included heavy machinery to stabilize the river bank, and engineering resources to investigate the landslide, and design a new discharge pipeline. The design of a new discharge pipeline included several unique characteristics to absorb future movement in the river bank, recognizing that the slide area would continue moving in the future. Construction of the new discharge pipeline occurred over the winter of 2004/05 and, included a number of cold region construction techniques. The new discharge pipeline was commissioned in June of 2005.

3.

Introduction

Fort Smith is located at 60o 00'N latitude and 111o 53'W longitude, and is the southernmost community in the Northwest Territories. The town is situated on the shore of the Slave River, south of the "Rapids of the Drowned" and immediately north of the NWT/Alberta border. Fort Smith is 322 air km southwest of Yellowknife. The banks of the Slave River are prone to landslides, the most serious of which occurred in 1968, and caused the death of an individual.

Another significant landslide occurred in August 2004, covering about 500 metres along the river bank, and destroying the community’s sewage discharge pipeline. The slide mass is located along the west bank of the Slave River immediately north of the Town, and close to the town's sewage lagoons. The discharge line from the sewage lagoons was located within the slide mass, and was severed when movement occurred (See Figure 1). This catastrophic event caused no injuries; however it destroyed the sewage lagoon discharge pipeline, which is a significant element of the Town’s waste management system. It was immediately recognized that the uncontrolled sewage discharge created by the landslide would require immediate attention in the form of stabilizing the slide area, and retaining the resources to design and complete construction of a new pipeline discharge system (See Figure 2).

Resources were immediately mobilized to start the process of replacing the discharge pipeline. These resources included heavy machinery to stabilize the river bank, and engineering resources to investigate the landslide, and design a new discharge pipeline.

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Limit of Landslide

Figure 1. Fort Smith landslide area.

Figure 2. Fort Smith sewage discharge pipeline after landslide.

The slide mass was about 650m wide, at the edge of the river and about 350 m wide in the crest area.

The length of the slide, from the scarp crest to river edge, was about 190 m. It was estimated that about 15 to 20 m (horizontal) of failed slope crest material was deposited on the upper portion of the lower slope area, and that about 15 to 25 m of material was pushed out into the river at the slope toe.

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Within days of the slide the Town of Fort Smith completed a temporary gravity discharge pipe (flexible hose) attached to the severed end of the original pipeline. The Town also began grading of the slide area to a depth of about 10 m below original grade, and the excavated material was pushed down slope into the slide zone. The purpose was to provide local stability in the escarpment, and to construct a uniformly graded access vehicles across to the edge of the river. The excavated area was about 100m wide and was sloped down at about a 6 percent grade. The base of the excavation intersected the original ground surface about 200 m behind the slide escarpment. This activity represented about 100,000 m3 of material that was excavated and replaced on the slide area.

2.

Geotechnical Assessment

Based on the historical information, the riverbank prior to the landslide was considered to be zone of marginally stable colluvium; the slope was about 35 m high, with an overall angle of about 13.0 degrees.

The ground surface was extremely rough which indicates ongoing movement and localized soil exposures.

The riverbank surface also contained numerous springs, surface erosion features, and ponds at various locations.

The depth to bedrock in the vicinity of Fort Smith is about 50 m below the ground surface. The materials immediately above the bedrock generally comprise clay layers, which are overlain by varying thickness of sand, silt and clay layers. The uppermost unit is comprised of sand layers with a thickness of 10 to 20 m; the thickness of the silt and clay layers is between about 15 and 40 m.

The slide originated in unconsolidated clay sediments above the bedrock surface near, or slightly below the level of the river. The slide is probably the result of both groundwater level fluctuations in the slope and on-going erosion at the toe in the river. The on-going erosion of the toe takes place over several years or decades and gradually reduces the bank stability to a state of eventual failure. The slide essentially adjusted the internal slope stability by creating a flatter profile. The process then repeats itself with alternating periods of marginal stability (on-going creep movements) and large slides.

In addition to continuing slide movement in the slope, the upper fill area of the slide, which was created by the Town immediately after the slide, will be prone to fill settlement. This may result in eventual total settlements at ground surface in the range of 450 to 750 mm in this area, however, the settlement is expected to occur over several years. Part of the settlement could occur quickly or suddenly if the loose fill becomes saturated. Settlement will be less in areas with thinner fill and will likely be almost zero at the edges of the fill mass, near the escarpment excavation and the middle of the lower slide mass.

In the lower slide mass, the ongoing slide movement will be primarily horizontal at probable rates of about 50 to 200 mm per year. As with the upper part of the slide, mass the rate of movement over the short term is likely greater than the long-term rate. Table 1 presents a summary of expected order-of-magnitude displacements in these two general slide areas.

Table 1. Summary of Expected Displacements.

2004 (mm) Slide Zone Upper Slide Zone Lower Slide Zone

Vertical 350 Near 0

Horizontal 200 200

After 2004 (mm/year) Vertical 350* Near 0

Horizontal 50 - 200 50 - 200

* Assumes maximum settlement from fill prorated over a period of about 5 years. When fill settlement slows the expected ongoing vertical movement rate will be similar to the horizontal rates for this zone after 2004.

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3.

Pipe Replacement Options and Related Issues

Given the magnitude and complexity of the ground movements in the slide area it was obvious that a buried replacement pipeline would not be an appropriate solution the problem. Two above ground solutions, based upon different pipe materials, (High Density Polyethylene (HDPE) and steel pipe) were developed and considered, along with an appropriate anchoring system, outfall structure and erosion control features.

3.1

HDPE Pipe on Ground Surface

The main advantage of installing of a flexible, insulated HDPE pipe directly on the ground surface is that it may accommodate the potentially complex movement patterns and magnitudes expected from the slide mass. Overall, the slide movement will tend to apply tensile forces to the pipe through lateral displacement toward the river and ground surface settlement. This could result in the pipe losing contact with the ground in some locations in the upper slide area and/or increased stresses in over bend areas in the lower slide areas. Periodic soil excavation and/or placement beneath the pipe will be required to maintain relatively uniform contact areas between the pipe and the ground surface, and to manage pipe stresses and strains due to pipe curvature.

3.2

Steel Pipe Supported On Sleepers

The main advantage of installing of rigid, insulated steel pipe supported on adjustable sleepers or cribs is that the need for periodic earthworks is generally eliminated. However, the locations and elevations of the sleepers will have to be adjusted periodically to maintain appropriate span lengths between support points and curvature of the pipe for proper stress conditions in the pipe. The support points should be placed directly on the ground surface to reduce the potential for induced stresses points due to twisting, leaning, or bending of elevated supports.

3.3

Outfall Structure

Movement at the toe of the slide mass could be significantly greater than the movement in the fill area.

Any outfall structure will move relative to the pipe and apply tensile stresses to the pipe unless a flexible connection is designed. An appropriate solution is comprised of a rock filled trench about 3.0 m deep with a sloped base to promote drainage toward the river, to reduce the potential for freezing in the winter, and to allow for annual fluctuations in the river elevation. The trench should be lined with a layer of woven geotextile to prevent migration of fines into the large void spaces of the rock trench.

3.4

Erosion Control

The sand in both cut and fill sections is prone to erosion from moisture and wind, and requires protection to limit the formation of ruts and gullies, and loss of material. Small drainage diversion berms/swales should be constructed at about 40 m spacing on the slope surfaces to direct runoff to areas away from the pipe and access road. In addition to diversion berms and grading for erosion protection, surface vegetation should be encouraged to regenerate in areas with exposed mineral soils to provide additional protection against erosion due to surface runoff and wind effects.

4.

Detailed Design

Based upon the geotechnical information and consultation with the Town, a replacement pipeline design was developed to address four specific design zones which included: stable ground; the upper slide zone; the lower slide zone, and the pipeline discharge zone (See Figure 3). The design criteria for the replacement pipeline included:

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Figure 3. Slide zones and anticipated slide movement

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1.

2.

3.

4.

5.

Pipe vertical stability in each zone; Pipe horizontal stability in each zone; Pipe Anchoring in the stable ground; Freeze protection of the entire pipeline; and Suitable discharge configuration.

Applying the experience that the Town has accumulated with a water supply pipeline in similarly unstable ground along the Slave River, two support configurations were developed for the pipeline replacement.

The upper support system consists of an I-beam â&#x20AC;&#x153;on edgeâ&#x20AC;? structure that cradles the pipe, and anchors it to the upper stable portion of the slide area; the I-beam is in turn supported by wood sleepers resting on the ground (See Figures 4 and 5). The lower support system consists of wooden sleepers with restraints bolted to each side (See Figure 6).

Figure 4. Pipeline support in upper slide zone.

Figure 5. Detail of pipeline support in upper slide zone.

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Figure 6. Pipeline support in lower slide zone.

The anchoring of the entire pipeline was accomplished by tying the I-beam into the base of a new manhole at the top of the slope, and tying the pipe itself to the I-beam. The lower support system is a series of wooden sleepers with blocks bolted to each side for horizontal constraint. Overall freeze protection was accomplished with a urethane foam insulating layer protected by a metal jacket (See Figure 7).

Figure 7. Detail of pipeline insulation

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5.

Construction and Commissioning of Pipeline

The design, and regulatory review of the late summer slide necessitated that the project be scheduled for winter construction in order to replace the pipeline as soon as possible. Consideration was given to postponing the construction until the following summer; however this was ultimately rejected because of the unknown performance of the temporary discharge during the very cold midwinter temperatures, and the availability of the emergency funding from the territorial government. It was recognized that the above ground configuration of the replacement pipeline would accommodate winter construction.

The insulated HDPE pipe was pre-purchased by the Town in order to advance the construction schedule as much as possible. The construction work was undertaken by a local contractor, and proceeded slowly, but steadily over the course of the winter. The most significant construction issue was the connection of the HDPE pipe on site. HDPE pipe is manufactured in discrete lengths and connected on site using butt fusions technology (heating and connecting of pipe ends). Problems were encountered with the butt fusion machinery, therefore the contractor elected to use electro fusion technology (couplers that adhere to pipe end using internal heat coils).

The strength and flexibility of the pipe system was put to the test in the spring of 2005 with an exceptionally high spring runoff in the Slave River, which pushed the pipe 20 to 30 metres downstream.

This occurred before the placement of the outlet anchoring system for the pipeline. The pipe length remained intact without any serious damage, and was pulled back into position and anchored The pipeline was commissioned in June of 2005. The total cost of the pipeline replacement (engineering and construction) was approximately $400,000.

6.

Conclusions

The design of the project was based upon the experience of the geotechnical consultant, the design engineers, and the operating staff of the Town of Fort Smith. This combination of experience has provided the Town with a very robust and timely solution to this catastrophic event.

Winter construction of civil related projects in the far north is generally expensive because of extreme temperatures and darkness that will significantly reduce working efficiencies. Frozen ground may also make excavation expensive and time consuming. This particular project was successfully executed during the winter because the majority of the construction was above ground, and the limited excavation was completed in very dry sandy soil.

7.

References

AMEC Earth and Environmental. 2004. Geotechnical Evaluation of Fort Smith Sewage Discharge Landslide.

AMEC Earth and Environmental. 2004. Preliminary Engineering Evaluation of Fort Smith Sewage Discharge Landslide.

Earth Tech Canada. 2004. Detailed Design Submission for Replacement of Sewage Discharge Pipeline.

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Livingstone Trail Environmental Control Facility (LTECF), Whitehorse, Yukon By

Ken Johnson, MCIP, P.Eng., Senior Engineer, Earth Tech Canada Glenn Prosko, P.Eng., Project Manager, Earth Tech Canada

Published in the Journal of the Northern Territories Water and Waste Association.

September, 2005. DEL Communications Inc. Ken Johnson – Editor.

Lagoons are the most common type of sewage treatment in Canada, and are often the treatment process of choice for small and medium sized communities because of their very low operating costs, and proven capability to achieve high quality effluent. This is particularly true for high latitudes where for the costs, and operation challenges of mechanical systems are magnified several times.

The City of Whitehorse used a four cell primary sewage lagoon system for may years, which provided appropriate technology for this community located at 60°34' N 135°4' W in the Yukon Territory.

In the late 1980’s regulatory demands for a higher quality effluent prompted the City to investigate options for achieving a secondary quality or better effluent. A number of studies were completed in the late 80’s and early 90’s considering mechanical and lagoon systems.

In the end, the terrain of an area to the north of the City, near what is called the Livingstone Trail, was able to accommodate a large lagoon system.

In 1994, work began on the Livingstone Trail Environmental Control Facility (LTECF) to serve the 18,000 people living in the City of Whitehorse.

The LTECF includes the following major detention and retention components (See Figure 1).

Figure 1. Livingstone Trail Environmental Control Facility (LTECF) 1

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• • •

Two 115,000 cubic metre primary lagoons with a combined retention time of 20 days Four 293,000 cubic metre secondary lagoons with a combined retention time of 100 days One 5.813 million cubic metre Long-Term Storage (LTS) pond with a one-year retention time.

The primary cells can fill to a depth of 6.2 metres and the secondary cells to a depth of 2.3 metres. The long-term storage area, a wetland three kilometres long and two kilometres wide, can fill to a depth of six metres. The flow between the lagoons is controlled by a variety of flow control structures (See Figure 2).

Figure 2. Flow control structure for LTECF. The facilities were constructed over a period of 2 years, and the work also included clearing and extension of the Marwell forcemain from the old Whitehorse primary lagoons to the LTECF, and upgrading of the other facilities associated with the collection system (See Figure 3). The completion of the work in September 1996, allowed the City of Whitehorse to end the direct discharge of primary treated sewage effluent into the Yukon River. The total capital cost of the LTECF was approximately $20 million ($1996), which was a cost of about $1,100 per resident.

The initial design of the facility included a discharge structure from the LTS for a seasonal discharge into the Yukon River. However with such a high quality effluent anticipated from the LTS, the City started considering an opportunity that would accommodate no direct discharge to the Yukon River. Adjacent to the LTS is a glacial pothole lake formation, which lies 16 metres below the level of the surrounding lakes, and lies less than a decimetre above the level of the Yukon River itself. The materials in between the pothole lake and the river are sands and gravels.

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Figure 3. Facilities associated with LTECF. The City applied to the Yukon Territory Water Board to obtain an additional Class A water licence for a trial discharge of up to two million cubic metres of fully treated effluent into the pothole lake. The discharge would gradually seep into the groundwater, along with other water from the lake, and very slowly make its way to the river. The trial discharge into Pothole Lake (PHL) was a success, and every fall since 1998 treated effluent has been discharged from the LTS pond into the lake (See Figure 4).

Time, wind and sunlight do most of the work at Whitehorse's new sewage lagoon. In a typical July, this City receives approximately 256 hours of bright sunshine and has an average daily temperature of 14°C; the average annual precipitation is 269 mm. The LTECF is designed to hold the sewage for at least 360 days at optimum capacity. During that time, the wind stirs the holding cells and puts oxygen into the system, helping microbes and natural

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Figure 4. Pothole Lake discharge for LTECF. chemical processes to break down the sewage contaminants. The only addition to the system is biological enzyme which enhances biodegradation.

By mid May of each year the secondary lagoons are generally "ice-free" and algal blooms quickly develop, significantly increasing the pH levels (maximum 11.3) and dissolved oxygen concentrations (maximum >20 mg/l). The elevated pH levels promote the volatilization of ammonia, reducing levels to below detection (0.005 mg/l) within 5 weeks of becoming icefree.

The City is generally pleased with the operation of the facility. The water licence states fecal coliform levels in effluent from the system may not exceed 2000 counts per 100 millilitres.

Tests of the new system have found fecal coliform counts ranging from less than 3 per 100 millilitres to a high of 240 per 100 millitres. The old system would discharge over 100,000 counts per 100 millilitres.

In 2003 approximately 3,770,000 cubic metres of sewage were received at the LTECF. In 2003 discharge of treated effluent from the LTS into PHL commenced on August 1, 2003 and ended on October 31, 2003, a total of 92 discharge days and a total of 3,374,660 million cubic meters of treated effluent was discharged into the Pot Hole Lake (See Table 1).

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Table 1. Discharge Effluent Quality Water License Max. limit for Constituent discharge of treated effluent BOD 45 mg/L Suspended Solids 60 mg/L Oils and Grease ** 5 mg/L PH 6-9 Ammonia N/A 2000 Faecal Coliforms MPN/100mL 2000 E.Coli MPN/100mL Giardia N/A Total Phosphorus N/A Dissolved Oxygen N/A 96-hour static LC50 100% (< symbol) less than detection limit

2003 Tests Effluent Quality data from LTS <4 <1 <1 7.8 <0.05

<1 0 3.32 2.1 100

The Livingstone Trail Environmental Control Facility is a showcase project demonstrating the opportunity for a sewage lagoon system to produce a very high quality sewage effluent at high latitudes in Canada, and essentially have a zero impact on the receiving environment.

Certainly it must be recognized that the surrounding natural features have a significant role to play in the treatment processes, and that the end product comes with a significant price tag in capital costs.

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PERFORMANCE AND POTENTIAL IMPROVEMENTS TO ANAEROBIC SEWAGE LAGOON IN FORT MCPHERSON, NT

Ken Johnson, Earth Tech Canada, Edmonton email: ken.johnson@earthtech.ca John Bulmer, Department of Public Works and Services, Government of the Northwest Territories, Inuvik email: John_Bulmer@gov.nt.ca Ron Rusnell, Department of Municipal and Community Affairs, Government of the Northwest Territories, Inuvik email: Ron_Rusnell@gov.nt.ca Michel Lanteigne, Earth Tech Canada, Yellowknife email: michel.lanteigne@earthtech.ca

ABSTRACT The Hamlet of Fort McPherson is a Gwich’in community located at 67o 27’ N and 134o 53’ W in the Northwest Territories. The main residential sanitary sewage system of the community consists of a trucked pickup, and a lagoon treatment system. Effluent from the lagoon is discharged once or twice a year, and enters a wetland, and stream system that ultimately discharges into the Peel River.

The area of the lagoon is approximately 1.81 hectares, and the estimated volume is 100,000 cubic metres. The performance of the sewage lagoon displays the characteristics of an anaerobic lagoon. The effluent suspended solids are in the range of 51 to 150 mg/L, and the effluent BOD5 is in the range of 17 to 70 mg/L. The effluent ammonia concentration is in the range of 11 to 34 mg/L. The sewage lagoon has sufficient hydraulic capacity for the next 20 years, and the However, concerns effluent quality is well below the existing water licence criteria. have been raised by regulatory agencies with the toxicity of the ammonia concentrations in the effluent. The “anaerobic” nature of the lagoon may not easily facilitate nitrification without some mechanical process addition.

An overview of the downstream wetland areas, and the quality of the discharge into the Peel River suggests that the wetland areas may have capacity for treating the ammonia in the seasonal lagoon discharge. With the support of additional biophysical studies, the sewage treatment “system” for the lagoon discharge could be expanded in the future to include the downstream wetland areas.

KEY WORDS: sewage treatment, cold regions, anaerobic lagoon, wetland discharge

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INTRODUCTION Background The Hamlet of Fort McPherson is a Gwich’in community located at 67o 27’ N and 134o 53’ W in the Inuvik Region of the Northwest Territories. The community is located on a high point of land on the east bank of the Peel River about 38 kilometres upstream from its confluence with the Mackenzie River. The level hill where the settlement is located is about 1.9 kilometres long by 0.8 kilometres wide, and is 15 to 21 metres above the summer water level of the Peel Channel. The townsite is 1100 air kilometres northwest of Yellowknife, and the Dempster Highway connects Fort McPherson to Inuvik, 220 kilometres to the northeast, and Whitehorse, Yukon 1200 kilometres to the southwest.

Fort McPherson experiences an average of 260 days with frost per year. The mean daily temperature in January is –29 °C, and in July, the warmest month, the mean daily temperature is 15 °C. About 115 mm of rain falls each year, and the the mean annual snowfall is 222 cm (Government of the Northwest Territories, 1982).

The sanitary sewage treatment and disposal system for the Hamlet of Fort McPherson is comprised of the trucked sewage system (approximately 85 % of effluent) and a piped sewage system (approximately 15 % of effluent). The trucked sewage system consists of a lagoon constructed in an abandoned shale borrow pit approximately 4 kilometres northeast of the community centre (See Figure 1) (Reid Crowther & Partners Ltd., 1997).

The piped sewage system consists of a lake discharge (“Sewage Lake”) immediately to the northwest of the developed community boundary. Effluent from both sewage systems enters a stream system that ultimately discharges into the Peel River, which is 2.5 kilometres downstream of the community centre (Earth Tech Canada, 2002).

In 2002 the Hamlet used a total of 39,596 m3 of potable water; the estimated water use is 114 L/c/d, based upon an estimated population of 945 people in 2001 (Government of the Northwest Territories, 2003). The monthly and annual quantities of all wastewater discharged is not metered, but is estimated to equal the quantity of potable water.

Approximately 33,300 m3 of wastewater (based upon average operating conditions) was trucked to the sewage lagoon, and the remainder of approximately 6,300 m3 flowed into Sewage Lake (Hamlet of Fort McPherson, 2003).

Trucked Lagoon Operation The lagoon is discharged in either the early summer or the fall, depending upon the water level in the lagoon. The discharge timing depends upon when the water level rises within about 1 metres of the top of the lagoon. The lagoon has a limited operating capacity because of a fixed culvert discharge, which limits the operating level variation of the lagoon to about 1.5 metres or 25,000 cubic metres of retention volume.

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The lagoon is discharged through the culvert, on the south side of the lagoon, into a 2 kilometre lake. The flow is controlled with a valve which is attached to the end of the culvert on the lagoon side of the culvert (See Figure 2) (Earth Tech Canada, 2003).

The flow discharges from the lake approximately to 2 kilometres from the lagoon, and flows into a wetland area before entering a stream that flows another 2 kilometres before discharging into the Peel River (See Figure 1).

System Characteristics and Performance Characteristics of Trucked Lagoon The impoundment receiving the sewage is an abandoned gravel quarry, which is generally a rectangular shaped impoundment with an overall length of 190 metres and an overall width of 90 metres; one small area at the north end of the impoundment is approximately 130 metres wide (See Figure 2) (Earth Tech Canada, 2003). The depth of lagoon various significantly, with depths ranging from 5 to 7 metres below the discharge culvert invert elevation. The area of the lagoon is approximately 1.81 hectares, and the estimated volume of the lagoon is 100,000 m3 (Earth Tech Canada, 2003).

The sewage treatment and disposal systems operate under the following water licence parameters: • • • • •

Effluent Faecal Coliforms Effluent BOD5 of seasonal discharge Effluent Suspended Solids of seasonal discharge Effluent pH of seasonal discharge Freeboard minimum in lagoon

106 CFU/100mL 120 mg/L 180 mg/L 6 to 9 1.0 metres

Anearobic Performance of Trucked Lagoon The effluent measurements over the past 7 years (See Figures 3 and 4) (Earth Tech Canada, 2003) demonstrate that the trucked sewage lagoon is well within the water licence parameters (Earth Tech Canada, 2003). The trucked sewage lagoon is a relatively deep (5 to 7 m) manmade impoundment, which operates as an anaerobic lagoon based upon its physical characteristics. The threshold depth for an aerobic pond is less than 1.5 metres, and the threshold depth for an anaerobic pond is greater than 2.5 metres (Metcalf and Eddy Inc., 1979).

Very little performance data exists for lagoon systems in the far north. The best comprehensive compilation of performance data has been compiled for lagoons in northern Alberta. The performance characteristics of the Fort McPherson lagoon fall outside the performance characteristics for facultative lagoons in northern Alberta lagoons (less than 2.5 metres deep) (Smith, 1996). The measured range of effluent values for BOD5 (17 to 70 mg/L – 7 year range) in Fort McPherson is above the compiled information for 12 month storage lagoons in northern Alberta (12 to 25 mg/L). The

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measured range of effluent values for suspended solids in Fort McPherson (51 to 177 mg/L â&#x20AC;&#x201C; 7 year range) is above the compiled information for 12 month storage lagoons in northern Alberta (45 to 80 mg/L).

The effluent ammonia concentration in the trucked sewage lagoon remains high, averaging 23 mg/L over 7 years, with a range of 11 to 34 mg/L. These high values suggest that the influent undergoes little or no nitrification.

Seasonal Performance of Trucked Lagoon The trucked sewage lagoon is discharged in the early summer and late fall, depending upon the water level in the lagoon. If the lagoon water level rises above the 1 metre freeboard elevation during the winter storage operation, the lagoon is discharged in the spring. Figures 4 and 5 suggest that different effluent characteristics may be expected for spring (before June 30), and fall (after June 30) discharges. A fall discharge may produce higher suspended solids ( 4 year average of 109 mg/L, and a range 46 to 138 mg/l) than a spring discharge (4 year average of 71 mg/L, and a range 42 to 138 mg/L). A fall discharge may produce lower BOD5 (4 year average of 36 mg/L, and a range 22 to 40 mg/L) than spring (4 year average of 51 mg/L, and a range 29 to 88 mg/L).

The higher seasonal values for suspended solids in the fall may be attributed to the more quiescent settling conditions in the winter and spring, and the algae growth in the summer months. The lower seasonal BOD5 in the fall may be attributed to the increased biological activity during the summer months.

The performance difference for spring and fall discharge has also been documented for the Yellowknife sewage lagoon system. Significant improvements were noted in BOD5 (greater than 85 % removal) and fecal coliforms (less than 1000 CFU/100 mL) in the period following the middle of June where the ambient air temperature reached its warmest for the year (Soniassy, R.N. and Lemon, R., 1986).

Characteristics of Peel River Discharge The discharge from both the trucked sewage lagoon (seasonal discharge) enters the continuously flowing small stream that discharges into the Peel River (See Figure 6).

The stream near the Peel River has a very small summer discharge (September 2003 observation), but occupies a reasonably large channel with significant stream debris (Earth Tech Canada, 2003). The mean flow in the Peel River itself ranges from 750 to 2000 cubic metres per second during the period between May and September (Environment Canada, 1997).

Water samples taken from the stream in early September, 2003 produced the following values (Earth Tech Canada, 2003): â&#x20AC;˘ â&#x20AC;˘

Suspended solids average of less than 5 mg/L; BOD5 average of less than 4 mg/L;

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â&#x20AC;˘ â&#x20AC;˘

Fecal coliforms average of less than 10 CFU/100 mL; Ammonia average of 0.28 mg/L.

There is little visible evidence that this stream is a receiving a sewage discharge based upon the limited inspection completed in September, 2003. Although the stream receives a periodic discharge from the trucked sewage lagoon, it also receives a continuous discharge from the piped sewage lagoon (See Figure 1). A fish was also observed in the stream at the time of the inspection.

Waste Generation and System Capacities The current sewage generation is estimated to be 114 litres per capita per day based upon the most recent water licence reporting (Hamlet of Fort McPherson, 2003). Of this generation, approximately 85 percent (33,000 m3 in 2002) is trucked sewage, and 15 percent (6300 m3 in 2002) is piped sewage. It is anticipated that these proportions may remain reasonably constant because the servicing strategy is expected to maintain the majority of the community on trucked services, and just the community core on piped services.

Table 1 presents a preliminary 20 year estimate of sewage generation based upon the GNWT population projections and the 2002 per capita estimate of sewage generation.

Table 1. Future Sewage Generation (Government of the Northwest Territories, 2003) Year

Population

2004 2009 2014 2019 2024 2029 2034 2039 2044

982 1,009 1,030 1,055 1076 1097 1119 1141 1164

Sewage Generation (m3) in Given Year (114 L/c/d or 41.9 m3/c/year) 41,150 42,280 43,157 44,204 45,084 45,964 46,886 47,807 48,771

The estimated volume of the lagoon is 100,000 m3, which provides enough capacity for 12 months of retention beyond the year 2044. It is assumed that 41,000 m3 of trucked sewage will be generated in 2044, which is 85 percent of the total 48,771 m3 estimated in Table 1.

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System Improvements and Future Expansion The existing sewage trucked sewage lagoon has sufficient hydraulic capacity for the next 20 years, and beyond, and the effluent quality is well below the existing water licence criteria.

The effluent quality could be expected to remain below the existing water licence criteria until the sludge accumulation begins to build up, and ultimately reduces the effluent quality.

The addition of primary sewage cells, to reduce the sludge volume in the lagoon, is not a necessary design practice for trucked sewage systems in the far north. Northern retention lagoons are commonly designed with a sludge zone to provide a region for sludge accumulation.

Concerns have been raised with the effluent toxicity from the ammonia concentrations in the lagoon influent. The general â&#x20AC;&#x153;anaerobicâ&#x20AC;? nature of the lagoon may not easily facilitate nitrification without the additional of some form of mechanical equipment to the lagoon such as aeration, therefore high ammonia concentrations may be anticipated in the future.

The addition of mechanical equipment to the lagoon system is not appropriate technology for the Fort McPherson lagoon because of the northern location of the community, and the distance from the community to the lagoon. The only source of electrical power is in the community itself, which is 4 kilometres away from the lagoon.

In anticipation of future demands for effluent quality improvements in toxicity and other parameters, the sewage lagoon system could be expanded to incorporate the downstream water bodies, and wetland areas as part of the overall treatment system (See Figure 6) (Earth Tech Canada, 2003). A preliminary review of these areas (shallow lake area and wetland area), and the discharge quality of the stream into the Peel River suggest that these downstream areas are already providing some degree of treatment to the lagoon discharge.

Seasonal wetlands in cold regions have very significant wastewater treatment capabilities. A wetland system in Repulse Bay reduced ammonia concentrations of 50 to 95 mg/L to less that 0.10 mg/L (Johnson, 1994). It would be reasonable to expect that the lake and wetland downstream of the Fort McPherson lagoon could achieve a significant reduction in ammonia concentration; a complete biophysical characterization of the lake and wetland system would be required to estimate the potential reduction.

The discharge operation of the trucked sewage lagoon utilizes a culvert with a fixed elevation, which restricts the operating levels in the lagoon to about 1.5 metres (25,000 m3). Future discharge operation of the lagoon should utilize a pumping system in order to draw down the lagoon for a 12 month retention, and a fall discharge (after June 30th).

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Conclusions and Recommendations The sewage treatment and disposal facilities for the Hamlet of Fort McPherson have sufficient hydraulic capacity for the next 20 years. In the operation of the lagoon, a fall discharge (after June 30th) may provide an overall higher quality effluent because of the additional retention (12 months in total) over the summer months. To achieve a 12 month retention period, the discharge control culvert may have to be abandoned in favour of a pumping system over the lagoon berm, which would accommodate a greater drawdown in the lagoon water level.

The downstream lake and wetland to the lagoon may provide additional treatment of the lagoon effluent with regard to nitrification of the wastewater. Therefore, in responding to existing environmental concerns, and in anticipation of future environmental concerns, and more stringent regulatory guidelines, a biophysical study of the downstream lake and wetland should be undertaken in provide a basis to incorporate the downstream water bodies, and wetland areas as part of the overall treatment system.

References: Earth Tech Canada, Fort McPherson Waste Study - Draft Report. October, 2003.

Prepared for the Department of Public Works and Services, Government of the Northwest Territories. October.

Environment Canada. 1997. Canadian Hydrological Data, Station: 10MC002 RIVER ABOVE FORT MCPHERSON.

PEEL

Government of the Northwest Territories, Bureau of Statistics. 2003.

Government of the Northwest Territories, Bureau of Statistics. December, 1982.

Community Water & Sanitation Services. Inuvik Region, Northwest Territories. .

Hamlet of Fort McPherson. April, 2003. 2002 Fort McPherson Annual Water Licence Report.

Johnson, Kenneth, R. June, 1994. Preliminary Engineering of Sewage Disposal System in the Community of Repulse Bay. Proceedings of the Annual Conference of the Canadian Society for Civil Engineering.

Metcalf and Eddy Inc. Wastewater Engineering. 1979.

Reid Crowther & Partners Ltd. September, 1997. Operation and Maintenance Manual, Trucked Sewage and Solid Waste Disposal Facilities for Fort McPherson, NWT. Smith, D.W., Technical Editor. 1996. Cold Regions Utilities Monograph, Third Edition, American Society of Civil Engineers.

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Soniassy, R.N. and Lemon, R. 1986. Lagoon Treatment of Municipal Sewage Effluent in a Subarctic Region of Canada (Yellowknife, NWT). Water Science Technology, Volume 18, PP 129-139.

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Fort McPherson, NWT Sewage Treatment and Disposal Systems Figure 1 195

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Mean Yearly Variation in Effluent Parameters 160 147 140 131 120

120

mg / L

100

95 88

87

80 70 60 51

57

40

20

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35

40 31

17

0 1997

1998

1999

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Year Total Suspended Solids

Biochemical Oxygen Demand

2002

2003

Figure 3

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Mean Yearly Variation in Total Suspended Solids for Spring and Fall Discharges 140 131 120

120 106

100

96 87

84

mg / L

80

60 52 40

42

20

0 2000

2001

2002 Year

Fall Discharge

Spring Discharge

2003

Figure 4

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Mean Yearly Variation in BOD5 for Spring and Fall Discharges 80 71

70

60 55

mg / L

50

40

30

49

37

40 35 31

29

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0 2000

2001

2002 Year

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2003

Figure 5

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LAND USE PLANNING AND WASTE MANAGEMENT IN IQALUIT, NUNAVUT Ken Johnson Engineer, Planner, and Surveyor UMA Engineering Ltd. ken.planner@home.com The City of Iqaluit, Nunavut, Canada’s newest Capital City, is unique in its location, its culture, and its infrastructure. Its place in Canada is even more interesting given the population of Iqaluit is less than 6,000 people. Its infrastructure not only includes specialized systems for water and sewer delivery and collection, but also special considerations for waste management. The waste management in Iqaluit includes both sanitary sewage treatment and disposal, and solid waste disposal. Both of these waste streams have had significant influence on the development of Iqaluit in the past, and will continue to have significant influence on the development into the future.

History of Waste Management The City of Iqaluit has had a continuing problem with solid waste management and sewage treatment and disposal within the community. The history of waste management in Iqaluit has evolved no differently than most remote communities, with convenience and low cost being the original criteria for waste management systems.

For solid waste management, this problem began with the use of multiple solid waste disposal sites by various military organizations in the 1950s and 1960s; the problem continued after the military left Iqaluit. The use of the military dump sites, and additional unorganized sites by the community continued. The end result has been a total of six known community solid waste disposal sites, none of which have incorporated proper waste management techniques, or proper site reclamation.

The sewage treatment and disposal systems for the City have also been problematic, however, prior to 1978, raw sewage was discharged from a number of pipes along the shore. The primary sewage lagoon system which presently serves the City of Iqaluit was a major improvement to sewage treatment in 1978.

The location of the sewage lagoon has been a concern of the community for many years because of its proximity to the community core and the airport. This proximity has raised concerns from the perspective of aesthetics, public health, and public safety.

The lagoon operation has operated to the general satisfaction of the regulatory authorities, however, it has suffered from a number of catastrophic failures of portions of the dike structure. These failures have been attributed to both tidal action at the toe of the dikes, and surface runoff intrusion and overflows to the top of the dikes.

These failures have been documented in the years 1981, 1984 and 1991.

The City of Iqaluit retained consulting expertise in the early 1990s to provide preliminary engineering for improvements for solid waste management and sewage treatment and disposal. The engineering work has also included work for the cleanup of the existing solid waste disposal sites within the community.

The consultant’s work on solid waste management produced a new landfill site that was placed in operation in 1995. This site represented a significant step forward in waste management because the site was planned and engineered to include landfill design parameters such as on-site and off-site drainage control, access control and engineered roads, appropriate consideration of setbacks, and operation and maintenance planning. The engineering of the new landfill also received the appropriate regulatory scrutiny and approvals in advance of its operation.

The preliminary engineering on sewage treatment and disposal produced several recommendations for system improvements in consideration of the current effluent quality standards, and improved effluent quality standards.

In implementing improvements to sewage treatment and disposal, the City chose to pursue a design build approach to a sewage treatment facility.

The spatial relationships for waste management and development are now reasonably well defined by the regulatory framework currently in place, with considerations of setbacks for residential and commercial development, natural habitat, and transportation.

However, the waste management practices of the past continue to influence development in Iqaluit because many of these setbacks were not been applied or enforced.

The waste management activities in and around the City include five abandoned solid waste sites and a primary sewage lagoon.

Landfill Practices and Spatial Framework in Cold Regions Landfills in cold region communities are evolving from waste management of convenience to engineered landfill sites. The evolution of waste management sites from the so-called “dump” to the engineered landfill sites has occurred over many years, and is far from finished.

Many landfills remain very unsatisfactory to regulatory officials from public health and environmental impact perspectives. The reasons behind the remaining

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2001: A Spatial Odyssey/Odyssée de L’espace poor waste management practices are many, and include insufficient resources for waste management to an incomplete understanding of what appropriate waste management should include.

The landfills utilized in the cold regions may be generally categorized into four different types of “depression” types, “embankment” types, “mound” types and “excavation” types. The depression and embankment types represent landfills developed from convenience rather than design. The mound and excavation types represent engineered landfills that cold region communities now strive to construct and maintain. Many local factors ultimately determine the ultimate configuration and location of the landfill in a community.

The lining of community landfills in cold regions with an engineered material has never been undertaken and is unlikely to be undertaken in the foreseeable future given the added cost and the limited community capital budgets.

The spatial framework for landfills is governed by several pieces of legislation, the most significant of which is the Public Health Act, and the associated Public Health Regulation. The General Sanitation Regulations to the Public Health Acts in Nunavut are intended to address the public health and safety aspects.

The Regulations state that no building used for human habitation shall be: • nearer than 450 m to a waste disposal ground; or • on any site, the soil of which has been made up of any refuse, unless the refuse has been removed from the site or has been consolidated or the site has been disinfected in every case and the site has been approved by a Health Officer.

Although the regulation conveys some discretionary authority by the Health Officer, in practice, the regulators have not exercised any discretion with regard to setbacks.

As well, the Regulations also state that every waste disposal ground shall be: • located at least 90 m from any public road allowance, railway, right-of-way, cemetery, highway or thoroughfare; and • situated at such a distance from any source of water or ice for human consumption or ablution that no pollution shall take place.

Other agencies that are part of the spatial and regulatory framework include: the Nunavut Water Board; the Territorial Department of Renewable Resources; the Territorial Department of Community Government and Transportation; Transport Canada; Indian and Northern Affairs Canada; the Department of Fisheries and Oceans; and Environment Canada. Each agency has a regulatory influence in the form of the operations, maintenance, environmental impact or spatial relationship.

Sewage Treatment Practices and Spatial Framework in Cold Regions A variety of treatment options for wastewater treatment and disposal are available for cold region communities, however, the ultimate choice for a community depends upon technology which is appropriate to the location. The treatment technologies available may be categorized into the two general areas of mechanical and non-mechanical treatment, which describes the mechanism by which the sewage treatment is completed.

Mechanical treatment may be characterized by the need for a power supply, construction to accommodate devices imported to the community, and a reasonably sophisticated operating system. A common example of a mechanical system is a rotating biological contactor (RBC).

Non-mechanical treatment may be best characterized by using the very common example of a sewage lagoon.

This system often does not require a power supply, and may be constructed using mainly local materials. Sewage lagoon systems may be constructed systems or existing natural impoundments of a natural depression or lake system.

Mechanical treatment systems have not been widely utilized in NWT or Nunavut communities. The use of mechanical systems in the NWT has, in a number of cases, been unsuccessful. Lagoon systems for cold regions may be categorized as continuous discharge (short detention and long detention), intermittent discharge, and zero discharge.

The regulatory framework for sewage treatment and disposal is similar to that for solid waste, with similar agency involvement and similar setback requirements.

Land Use Bylaws and Waste Management The Town’s General Plan Bylaw was developed with sections to specifically address waste management past, present, and future in the context of land use planning.

The specific wording in the Bylaw includes the following passages devoted specifically to waste management: 1. The City will continue to evaluate options for long-term sewage treatment, including the relocation of the lagoon, or tertiary sewage treatment at the present site. The evaluation will consider cost-effectiveness, the degree of environmental protection and the land use implications.

2. The City will reserve a site in West 40 (west limit of the community) as shown on the Future Land Use Concept as a potential site for the relocation of the sewage lagoon. If another option for sewage treatment is adopted; then other potential uses for that site will be considered.

If the best solution is the relocation of the sewage lagoon, the existing site will be restored and consideration given

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2001: A Spatial Odyssey/Odyssée de L’espace to a second or relocated road link between West 40 and the rest of Iqaluit.

3. The City shall continue to evaluate all possible options for an integrated waste management system, including the suitability of the new landfill suit for long-term use and also considering complementary strategies such as source reduction, reuse, and recycling of waste materials.

4. The City shall continue to encourage the responsible federal, territorial and other agencies to assist in the clean up and restoration of the six landfill sites which are the legacy of fifty years of indiscriminate waste disposal. The City shall seek suitable end uses, such as recreational use, for these restored sites.

Future Waste Management This national spotlight for the City of Iqaluit has given rise to an increased awareness in many aspects of the community’s infrastructure, particularly waste management. Although the current practice of landfilling and open burning in an engineered landfill site is the status quo for most of northern Canada, this is no longer a desirable practice in the City of Iqaluit, particularly at the current landfill site in the West 40 area.

A sitting study was recently completed to position the City of Iqaluit to proceed with the implementation of a new waste management plan.

The siting study encompassed the entire area within the Municipal Boundary in order to satisfy any potential criticism in the siting process. Clearly, distance to a site becomes a significant factor from the onset given that the capital cost of an access road may exceed $250,000 per kilometre, and that operation and maintenance costs in the winter would be very expensive as well.

Ultimately implementation of a site will be based upon environmental and land use criteria, technology, and stakeholder and community consultation to gain acceptance of a site. The criteria for an environmental assessment of any particular site will also vary depending upon the site. The City of Iqaluit is suggesting that it will pursue the implementation of a solid waste incineration system to be located in the industrially zoned area. The implementation of this technology will ultimately depend upon available capital funding (in excess of $3 million), and sustainable operation and maintenance funding (in excess of $300,000 per year).

The City Iqaluit is also working toward the start-up of a new tertiary sewage treatment plant which may provide high quality treatment to serve the City well into the future. This $7 million capital project, with an operation and maintenance demand in excess of $400,000 per year, is awaiting completion of project deficiencies.

An interesting opportunity has emerged for some

residents in the Apex neighbourhood of Iqaluit. A technology known as wastewater recycling has received funding for a trial program for an 11 house cluster. This system would take wastewater from each house and complete a tertiary treatment process before pumping it back to be used to flush toilets and do laundry. Residents would still get a fresh supply of water for drinking and bathing. The water system is an innovative environmental project the City is banking on to conserve Iqaluit’s water supply Recycling wastewater is expected to reduce water consumption (from 1,825,700 litres a year to 912,850 litres a year) and cut down the number of water deliveries to households (4,000 to 100 per year).

The growth in Iqaluit over the past three years has put a tremendous strain on the City’s waste management systems. This, in turn, has placed demands and expectations on the City’s land use planning efforts related to waste management.

These improvements to the current waste management practices in the City of Iqaluit will improve the presentation of the community as a Territorial Capital, and also improve the development situation with regard to regulatory setback requirements for public safety, public health, and environmental protection.

Biography Ken Johnson is an engineer, planner and surveyor from St. Albert, Alberta. Ken’s formal training includes a Bachelor’s Degree in Civil Engineering, a Master’s Degree in Civil Engineering, and Certificates in Site Planning and Survey Technology. Ken is a registered Professional Engineer in the Yukon, Northwest Territories, and Nunavut, and the Province of Alberta.

Ken is also an Associate Member of the Alberta Land Surveyors Association, a Provisional Member of the Alberta Association of the Canadian Institute of Planners, and past Chair of the Cold Region Engineering Division of the Canadian Society for Civil Engineering.

Ken’s professional experience in the Canadian north spans a period of 14 years; during 5 of these years he spent some time as a resident of each of the 3 Territorial Capitals. He has worked as far north as Canadian Forces Station Alert, and to the eastern and western limits of the Canadian north. Ken has provided consulting expertise in the areas of cold region municipal engineering, cold region environmental engineering, and land use planning in remote communities. His current areas of interest and study are land use planning and climate change in cold regions, on-site wastewater recycling in cold regions, and land use planning and waste management in cold regions.

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IQALUIT SEWAGE LAGOON Site Plan

Figure 1 257

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IQALUIT SEWAGE LAGOON Effluent Suspended Solids mg/L

Figure 2

Effluent Suspended Solids

Average Influent Concentration

Date

IQALUIT SEWAGE LAGOON Figure 3

Effluent BOD5

Effluent BOD5 mg/L

Average Influent Concentration

Date

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IQALUIT SEWAGE LAGOON Figure 4

Effluent BOD5 mg/L

Tr e nd in

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Effl uen t BO D5

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IQALUIT SEWAGE LAGOON Figure 5

Effluent Fecal Coliforms

Effluent Fecal Coliforms (col/100 mL)

Average Influent Concentration

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IQALUIT SEWAGE LAGOON Figure 6

Effluent Fecal Coliforms (col/100 mL)

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Effluent FC vs Air Temperature

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ALTERNATIVE CONCEPTSFOR WATER AND SEWER MAIN ACCESSIN THtr NORTHWEST TERRITORIES K.R. Johnson,IJMA EngineeringLtd. (kjohson@uma$oup.com) B.C. Grieco,tlMA Engineering Ltd. (bgrieco@umagoup.com) ABSTRACT A studyto investigatealtematelesscostly accesssystemsfor below ground water andsewer main servicingwasundenakenby UMA EngineeringLtd. on behalfofthe Govemmentofthe NorthwestTerritories. The systemmost commonlyusedin permafiostareasofthe Nofihwest Territoriesis a buried insulatedsteelaccessvault.

The studywasbasedon a decisionanalysisofa numberofaltemative concepts.lnfbrmation for the conceptswasbasedon a surveyof inftastucture accesssystemsin Aiaska, the yukon Territory, the Northwest Teritories and the Nunavut Tgrritory. Theseconceptswere then refined,andcombinedto provide a largenumberofpotential accesssystems.

A total of l7 altemativeswere evaluatedusing a Kepner-TregoeDecislon Alalysis. The evaluationindicatedthat the threehighestruking altemativesfor accessto sewerandwater mains(in decreasingrar*) are: .

Commonbelowgroundmainswith insulatedsteelaccessvaults.

.

Commonbelow groundmainswith insulatedHigh Densitypolyethylene(HDPE) access vautts.

Separatebelow groundmainswith shallowinsulatedHDPE water accessvaults, (requiringa portableshelter),andinsulatedHDPEseweraccessvaults.

265

1.0 INTRODUCTION altemate,less costlyconcepts to theinsulated steelwater A studywasundertaken to investigate andseweraccess vaultcurrentlyadoptedby theGovemnentofthe NorthwestTerritoiesfor water and sewer main servicingin theNWT. buied Altemativeconceptswere developedand assessed using the Kepner-Tregoe methodof DecisionAnalysis.Thismethodrequiresthata hierarchyofobjectivesbeestablished, against whichthe altemateconceptsareevaluated.

The currentdesignwhich utilizesa corDmoninsulatedsteelaccessvault for bothwaterand sewersystems is theresultofnearly20 yearsofdesignevolution.Prcblemswhichcomrnonly vaultsincludedwaterinfiltration occunedwith the earliersystems ofwater andseweraccess insulation,difficultyof intothevaults,physicalandmoistuedanageto theintemalurethane access to appurtenances, andfreezebreakage ofpiping andappurtenances.

The insulatedsteelaccessvaultwhich is presentlyused,hasrectifiedall oftheseproblems with the previousdesigns.However,thesevaultsmay costin excessof$39,000. associated ofall fittingsandappurtenances, butdoesnotinclude Thiscostincludes supplyandinstallation ofthe mobilizationand demobilization.The costofthe accessvaultsmay represent30o% contractp ce for the pipedutilitiessystem.

2.0 METHODOLOGY The data collectionwas basedon a surveyof accesssystemsin Alaska and the Yukon. otherthanwaterandsanitationdepartments suchastelephone utilities Govemmentagencies were also co[tacted. None of the groupscontactedhad developeda specialdesignfor permafiostareas;rather, they usedstandardprefabricatedconcreteor metal sections. waterandsewermainswâ&#x201A;Źredevelopedthroughgroup Thealtemativeconceptsfor accessing in coldregion,municipal,andmechanical engineering. discussions ofUMA staffexperienced ofthe AdditionalinputwasobtainedfromtheMunicipalandCommunityAffairs Department NWT eovemment.

3.0 ALTERNATIVE CONCEPTS 3.1

AccessFrom Wilhin A Structure

withinthisgroup,assumnrarized in thefollowingTable1, maybe Thealtemative concepts accessed furtherclassifiedashavingfittingsandappurtcnanccs in a belowgroundstructure, andfittingsandappu enances accessed in an abovegroundstructufe.

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3.2

DirectBuriedAccess

Thedirectburiedconceptinvolves fittingsandappurtenances whicharcindividuallyinsulated and individuallyaccessed.Methodsfor insulatingand accessingthe variousfittings and appurtenances arcdescribedin thefollowinssections.

3.2.1 WaterMain Appurtenarces Thethawaccess for watermainwouldemployathawlanceto watermainsin eitherdirection.

Thestructurewouldbe built from two backto back45olaterals.Freezingofthe watetrn the lateralsmay occur,however,expansion ofthe ice wouldtakeplacelowe;own in thelateral, sothatdamagefiom freezeexpansion wouldbe rmlikely.

The drain for water main would employoneoftwo systemsto drain a direct buriedwatermain withoutaccess vaults.Thethawaccess shownin Figures2 and3 could beusedto gainaccess for pumpingoutthesystem.Altematively,a drainandvalvecanbeplacedat low pointsin the systemwith the dtainpipeextended to a ditchor naturalwatercourse.

Thefire hydrantwould becoveredwith field sprayedinsulationandsheetmetal. Altematively, thehydrantandteecouldbecoveredwith preformedurethanehalvesandpreformedgalvanized sheetsteelsplit covers.The hydrantbanelwouldbe filled with propyleneglycol antifteeze.

Themethodofinsulationandcoverfor thevalvewouldbe the sameasfor thehvdrant.

3.2.2 SewerMain Appurtenances The surfacecleanout andthaw accessfor sewermain shownin Figue 3 may be utilized asa sewermaln thaw accessandcleanout. A secondarrangement, shownon Figure2 mayalso beusedfor sewerthawandcleanout. With thisaltemative, morepipingis required,however, only onecleanout coveris available/requited for access.

Themanholefor thesewermainwould employanuninsulatedbody (standardprecastconcrete) anda fabricated, insulated, removable covermadeto suiteachmanlolepipeconfiguration, and all piping would be insulatâ&#x201A;Źd.A secondt)?e of manholewould utilize a small,shallow manholewith access to thesewerlinesfromthetop ofthe manholeonly. Themanholewould be insulatedon theinteriorandthemanholewouldbe watertisht.

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4.0 DECISIONANALYSIS The Kepner-Tregoâ&#x201A;Ź methodof DecisionAlalysis involvesthe systematicevaluationof a numberofdeveloped feasiblealtematives againstahierarchyoffrxedobjectives.Any feasible altemativeis subsequently adjudicated intems ofthepossibleadverse consequences ofusing thealtemative.

4.1

Must Objectives

Must objectivesarc defined as thoseobjectiveswhich must be met for an altemativeto be coNideredfurther.The list ofmust objectivesweredeveloped in consultation with all those involvedin theprojectasfollows: . . . . . . . . . . . .

Accessfor sewercleal out; Accessfor thawingsewermain, Accessfor draining water main, Accessfor thawing water main; Accessto operate,maintain andrepair appurtenances; Hy&ant drain and hydrantcontentsdo not freeze; Resistarce to all uplift forces; Resistanceto thaw settlement; Preventsall ingressofwater; Minimum20 yearlife; Prctectionagainstfreezedamageby utilizing theheatwithin the waterard sewermain; and Accommodates thrustforcesdueto expansion andcontractionofpipe.

4.2

WantObiectivâ&#x201A;Źs

The want objectiveshaveweights assignedto themwhich indicatestheir relativeimportance.

All altematives aresubsequently ratedasto how well theysatisfyeachwart objective.The useofwant objectivesprovidesfor a comparison ofalternatives.

Capital CostObjectives ' Low fabricationcost; .

Low installationcost; .

Easyshippingandhandlingfor groundor seatansportation;and .

Minimizedfield installationwork.

Maintenance Objectives .

Maintenance wo.k to bedonein a sheltered portableenvironment with powerfacilities for heatandlight; .

Spillsor leakageto be easilyremoved;

269

for knownoperatingconditions; Durableconstruction Vandalismresistance; andrepairsdoneusinglocalresources; Maintenance Minimurn but adequatespaceto perfom r€pair; and Easylocating and accessingunderpoor w€atherconditions.

Other Objectives .

Competitiveproductionin theNWT; . possiblefor unplanned futue extensions; Field modificationsor alterations .

Minimum tumaroundfor manufactureofcomponentsin system; .

Easyrcmovaland/orrcplacement; .

Minimumpotentialofcontamination ofwatermainfrom sewermainor othersources; .

Original groundthermalregimemaintained;and .

OccupationalHealth and SafetyStandaldsmet.

4.3

Analvsis

Thewater andsewermain accessconc€ptsandsystemswerc rcfined andcombinedto produce analysis,someof all possibleaccess systems.Beforesfaxting with the formalKepner-Tregoe the more impractical altemativeswere removedAom the listA total of 13 accesssystemsmet all l2 must objectivesand were analyzedusing the 18 weightedwantobjectiveslisted.Theaccess systems with theirindividualweightedscoresfor eachobjective,subtotalweightedscoresfor eachofthethreecategories ofobjectives,andtheir totalweightedscoreswerecalculated. with theirsubtotalandtotal weightedscoresare: Thethr€emostpr€ferredaccess systems, 1.

Commonbelow groundmainswith insulatedsteelaccessvaults(existingsystemTable1 - AlL 1, Figure1) CapitalCostScoreSubtotal Maintenance ObjectivesScoreSubtotal OtherObjectivesSubtotal Total WeightedScore

537 1,350 994 2,881

Commonbelowgroundmainswith insulatedHDPE accessvaults(TableI - Alt. I, Figure1) Capital Cost Subtotal MaintenanceObjectivesSubtotal Other ObjectivesSubtotal Total Weighted Score

800 I,032 918 2,750

270

3.

Separate belowgroundmainswith shallowinsulated HDPEwateraccess vault,which requiresa portableshelter,andinsulatedHDPEsewetaccessvault (Tablet - Alt. 7, Similarto Figure3 exceptwith separate seweraccessvault in placeof surfacesewer cleanouts) CapitalCostSubtotal MaintenanceObjectivesSubtotal OtherObjectivesSubtotal Total WeightedScore

692 |,046 850 2,588

5.0 CONCLUSION As a resultofthis studyandDecisionAnalysisofaltemativemethodsofaccessingwaterand sewermains,thteeimpotant conclusions canbe drawn. The conclusions are: 1.

At thistimetheexistingburiedinsulated steelaccess vaultis thehighestrankingdesign for accessing belowgroundwaterandsewermains andappurtenances in theNorthwest Territories,for thepurposeofopention, maintenance andrepair.

2.

The buriedinsulatedHigh DensityPolyethylene (HDPE)commonaccessvault is a potentiallowercostaltemativeto theinsulatedsteelaccess vaultwhichmaybesuited for cetain applications.The suitabilityof the HDPE accessvault requiresmore investigation beforeit canbe considered for installationin the NorthwestTenitories.

3.

A systemincludingan insulatedHDPE sewer(only) accessvault and a separate shallowinsulatedHDPE water (only) accessvault is also a potentiallower cost altemative, althoughlesspromisingthanothers,to theinsulatedsteelaccessvault.

The suitabilityof the HDPE accessvault requiresmore investigationbeforeit canbe considered for installationin theNorthwestTerritories.This systemutilizesa portable shelterwhich also requiresinvestigationand designwith input from experienced specialists.

271

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