Charting a New Direction for Wastewater Treatment in Nunavut

WCW16 Annual Conference & Exhibition October 4-7 2016 Calgary AB wcw16.wcwwa.ca CHARTING A NEW DIRECTION FOR WASTEWATER TREATMENT IN NUNAVUT Kenneth Johnson, Stantec Consulting Ltd., Edmonton

ABSTRACT The so-called “leaky lagoon” was a generally accepted design concept for many years in the Nunavut Territory, formerly the Northwest Territories. However, because of the application of more stringent effluent quality standards, and the requirement of a controlled effluent discharge, this design concept is now unacceptable. The current design concept applied for lagoon systems in the far north is a retention lagoon with a seasonal discharge. In addition, the use of wetlands has emerged as a supplementary process for lagoon systems.

The construction of retention lagoons applies modern geomembranes in many cases because of the absence of fine soil materials for the construction of structures with low permeability.

New issues are emerging with the construction of these relatively complex earth structures because of the extreme cold climate, permafrost earth regime, and construction techniques.

The anticipated costs of remedial work to address these issues are in the order of ½ of the original capital costs of the original multi million dollar structures, which are beyond the available capital funding.

A much needed new direction is being charted based upon research to develop the northern science for wastewater treatment. This science is being communicated to the audience of regulators, as well as the communities to incorporate the “social science”, and “applied science” or engineering is also being incorporated. With this activity it is anticipated that a new, more appropriate direction for wastewater treatment may emerge for Nunavut.

Keywords: wastewater, Nunavut, lagoons, science, engineering

INTRODUCTION The so-called “leaky lagoon” was a generally accepted design concept for many years in the Nunavut Territory, formerly the Northwest Territories. However, because of the application of more stringent effluent quality standards, and the requirement of a controlled effluent discharge, this design concept is now unacceptable. The “leaky lagoon” had many positive characteristics regarding the treatment of wastewater.

The leaky lagoon provided the opportunity for solids settle in the lagoon, and thus potentially providing primary sewage treatment. The effluent would discharge from the lagoon by “seeping” out through earth berms, which would provide further sewage treatment by filtration. These systems were simple to construct, and could make use of whatever granular materials were available for construction. With long term operation the voids in berms would clog after several

years providing additional detention. A key element of the leaky lagoon was its capability to adjust to the dynamic earth environment which is prevalent in permafrost soils.

Figure 1: “Leaky” lagoon with adjacent wetland in Ulukhaktok, Northwest Territories

ENGINEERING THE RETENTION LAGOON SYSTEM Applied science or engineering 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.

The current engineering design concept applied for lagoon systems in the far north is a retention lagoon with a seasonal discharge. In addition, the use of wetlands has emerged as a supplementary process for lagoon systems.

Figure 2: Kugaaruk, Nunavut sewage treatment facility

As an example, the sewage lagoon serving the Hamlet of Kugaaruk is a granular earth berm structure, which was a reconstruction of an existing leaky lagoon that was previously used for wastewater detention. The lagoon has a rectangular configuration approximately 150 metres long and 90 metres wide, and an impermeable bentonite membrane integral within the berm structure.

The construction of the Kugaaruk lagoon applied modern geomembranes because of the absence of fine soil materials for the construction of a low permeability earth berm.

Containment is provided by an impermeable liner embedded within the berm. The base of the liner was anchored into bedrock at depth via a key trench with low permeability backfill or grout.

Larger rip rap stone provides erosion protection on the face of the berms.

Figure 3: Kugaaruk, Nunavut sewage lagoon berm profile.

RETENTION LAGOON PERFORMANCE Retention lagoons combined with supplementary wetland treatment may provide an excellent effluent quality with discharge in the late summer or early fall. The effluent quality may meet or exceed the CCME effluent quality standards of CBOD and SS below 25 mg/L. As good as the lagoon/wetland system may perform, the system is ultimately influenced by the weather in any particular year, and therefore the effluent quality may vary significantly from year to year.

The retention lagoon in Kugaaruk was designed for discharge through a pipe constructed into one of the berms, which discharges into a flow dispersion structure and ultimately into a wetland. However, this pipe system froze and the discharge is now completed by pumping over the berm.

Unfortunately, a seepage notable flow from the base of the lagoon has developed, which contravenes the operation of the facility as a retention lagoon. The flow originates from two general areas of the berm, and from specific flow points in each area. The regulators have advised that this condition is unacceptable for the lagoon operation, and the Government of Nunavut has initiated action to advance remedial work on the berm. Similar issues are occurring in other lagoons in the communities of Kugluktuk, and Cape Dorset. These are new issues that are emerging with the construction of these relatively complex earth structures that are influenced by the extreme cold.

Options for remedial work on the Kugaaruk lagoon have been developed, and include remedial work to eliminate the seepage, and remedial work to manage the seepage. The remedial work to eliminate the seepage has capital costs in the range of $1 million to $4 million. A zero cost option was identified to eliminate seepage by the accumulation of sewage sludge, however, this option would have a very low probably of success,. The remedial work to manage the seepage has capital costs in the range of $640,000, to $1 million.

Figure 4: Seepage flow from sewage lagoon in Kugaaruk, Nunavut.

The anticipated costs of remedial work to address these issues are up to ½ of the original capital costs of the original multi million dollar structures.

SCIENCE AND SCIENTIFIC STUDY OF NORTHERN WASTEWATER 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.

To advance the science of wastewater treatment in Nunavut, Dalhousie University was retained by the Government of Nunavut in 2012 to study local wastewater systems and monitor performance. The study determined that in most cases for communities in Nunavut, the volume of wastewater is very low, on average, 100 litres of water per person per day, compared to 300 litres per person per day for the average Canadian. In addition, all of the communities are located on the ocean, which as a receiving environment for a lagoon discharge quickly dilutes and disperses the effluence discharge.

The study monitored the lagoon/wetland process, which operates by a discharge at the end of summer, after the ground has thawed, and solids in the lagoon have settled. The discharge from the lagoon is released into a wetland tundra area, where plants, soils and naturally occurring bacteria filter out or consume bacteria such as E. coli. It was noted in the study that the effluent discharge should ideally flow through the wetland for a minimum 14 days for sufficient treatment.

Figure 5: Sampling of discharge area of sewage lagoon in Coral Harbour, Nunavut The study included the community of Pond Inlet, Nunavut, which has only a lagoon, and not wetland. The discharge at the end of the summer is released over a rocky embankment, which leads directly to the ocean. It was observed that the environmental impact on the ocean is “minimal.

THE SOCIAL SCIENCE OF NORTHERN INFRASTRUCTURE 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 government representing the aboriginal community, as well as the non-aboriginal community; 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, and departments may number 6 or more. The resources available to remote communities have been challenged over the past decade in this multifaceted, dynamic and demanding environment.

This science of wastewater treatment in Nunavut is being communicated to the audience of regulators, and to some degree to the communities to incorporate the “social science” into the design and regulatory processes. Accounting for the community’s interest in water and sanitation is not a new phenomenon in the far north, but it is a phenomenon with a renewed importance in the delivery of water and sanitation projects. Community residents are usually initially interested in improving services, but are often confused and frustrated by the long planning process, and detailed technical and economic evaluations that are conducted to rationalize the simple improvements they want.

Engineers often set up community meetings with a tight time schedule, residents spend a great deal of time telling stories before getting down to business, and the engineer may leave the meeting frustrated because little was accomplished. Listening to the community takes more time than what has been traditionally' allotted, and “telling stories” is an important method for indigenous people, particularly elders, to make comments and answer questions. The engineer

must listen closely to these seemingly irrelevant stories, for often they will contain key opinions concerning the subject at hand.

The technology and the planning process may be new to residents, so planning process also has an educational role. The issues, data, analysis and technologies must be presented in ways and language which the residents understand. It is a challenge to integrate the knowledge of the engineers with the traditional knowledge and values of aboriginal residents. In the past, most decisions were made primarily by a senior government, so truly active participation in planning is a new process in many communities. Both the community and the engineer must recognize this, and face it as a learning experience, listening to one another and remaining flexible in the methods of execution.

POTENTIAL FOR A NEW DIRECTION The application of science for wastewater in a northern context is still a work in progress, but major progress has been made over the past several years with the research by Dalhousie and others. A key next step in for the Government of Nunavut needs to draft design standards to make sure that the systems across the territory are designed, upgraded and operating to the same level of service.

In the design of a lagoon system, the key principles of appropriate technology, community context, incremental improvement have been applied inconsistently to projects in remote communities. As a consequence of not following these principles and other issues, a significant number of projects are not meeting the performance expectations of the communities, and the regulatory authorities.

Nunavut communities have a direct interest in all of these principles, and their associated outcomes because the wastewater facility will ultimately become a community legacy, which may impose health and safety, financial, and human resource conditions on a community for a generation into the future.

The science, applied science, or engineering, and social science all have roles to play in the Nunavut dialogue, and the ultimate objective to improve wastewater management. With this dialogue, it is anticipated that a new, more appropriate direction for wastewater treatment may emerge for Nunavut.

REFERENCES Jamieson, R. 2016. Understanding and Optimizing the Performance of Municipal Waste Stabilization Ponds in the Far North.

Johnson, K. 2007. The Social Context of Wastewater Management in Remote Communities, Proceedings of Western Canada Water Conference.

Johnson, K. 2015. Water and Sewer Infrastructure in Cold Region Communities, Unpublished Report.

Stantec Consulting Ltd. 2015. Kugaaruk Sewage Lagoon Study.