Page 1

Volume 37 No 2

APRIL 2010

AWA JOURNAL OF THE AUSTRALIAN WATER ASSOCIATION

MANAGED AQUIFER RECHARGE • PIPES • STORMWATER HARVESTING


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Major water network operators like Brisbane City Council, ActewAGL Wate Division, SA Water, and Barwon Water all rely on Bentley products every day.


water

Journal of the Australian Water Association ISSN 0310-0367

RECLAIM Water: Research Results - see page 62

TECHNICAL FEATURES( ~

Volume 37 No 2 April 2010

contents

Urban Stormwater Supplies Drinking Water at Orange, NSW - see page 75

INDICATES THE PAPER HAS BEEN REFEREED)

DEMAND MANAGEMENT

Smart Water Metering in the Victorian Urban Water Sector The urban water corporations across Victoria are coordinating further analyses

P Harris, P Guttmann

44

P Dillon, D Page, J Vanderzalm, S Toze, J Ward

54

S Toze, E Bekele, Z Leviston, B Patterson

58

C Kazner

62

C Tanner, S Leinster, D Hamlyn-Harris

67

C Devitt

75

R Butler, A Sneddon, M Schwecke

80

MANAGED AQUIFER RECHARGE

[11 The Pathway from Boutique to Mainstream Water Supply A passing fad or here to stay? [i]

Recycling Water via Infiltration Galleries in Urban Groundwater Sustainable recharge in shallow aquifers can be achieved RECLAIM Water: Research Results Managed aquifer recharge can be safe and reliable for water recycling STORMWATER HARVESTING

Stormwater Harvesting as a Water Source for South-East Queensland Assessment demonstrates that stormwater harvesting is a feasible alternative

[Al

Urban Stormwater Supplies Drinking Water at Orange, NSW

The first scheme to harvest an urban catchment PUMPS & PIPELINES

[i] Pump and Heating Efficiency Solutions for High Rise Buildings Improving the water and energy nexus SKILLS SHORTAGES & EDUCATION

The H20Z Campaign: An Industry-Wide Response to the Skills Shortage in the Australian Water Industry

FMackenzie

85

S Rhodes, C Elston, C Neilson, D Hardy

87

Z Slavnic

94

PGriffiths

96

[I] SEQ Water Grid Strategy for Skills Formation Building institutional capacity through people WASTEWATER TREATMENT

Intermittently Decanted Aerated Lagoons - Improving Nitrogen Removal Better nitrogen removal achieved by modifying the aeration software

[I] Wetalla Plant Sets New Standards for EPBR Design and Operation Outstanding performance achieved through Alliance Optimisation WATER BUSINESS

New Products and Business Information

102

Advertisers' Index

112

2 APRIL 2010 water


water

Journal of the Australian Water Association ISSN 0310-0367 Volume 37 No 2 April 2010

contents REGULAR FEATURES From the AWA Chief Executive And Now for the Good News My Point of View

T Mollenkopf 4 T Priestly

Crosscurrent

5 8

Aquaphemera

R Knee 10

Industry News

13

AWA News

19

Events Calendar

22

Release of Fellowship Reports - see page 13

FEATURE REPORTS 0zwater'10 - Special Report EA (Bob) Swinton

26

Planning for the Future

32

Prime Minister Recognises Waterwise Businesses

34

AWA Awards the Best in the Sector

36

Defining Catchment Management Arrangements

40

AWA CONTACT DETAILS Australian Water Association ABN 78 096 035 773 Level 6, 655 Pacific Hwy, PO Box 222, St Leonards NSW 1590 Tel: +61 2 9436 0055 Fax: +61 2 9436 0155 Email: info@awa.asn.au Web: www.awa.asn.au DISCLAIMER Australian Water Association assumes no responsibility for opinion or statements of facts expressed by contributors or advertisers. COPYRIGHT AWA Water Journal is subject to copyright and may not be reproduced in any format without written permission of the AWA. To seek permission to reproduce Water Journal materials, send your request to media@awa.asn.au WATER JOURNAL MISSION STATEMENT 'To provide a journal that interests and informs on water matters, Australian and international, covering technological, environmental, economic and social aspects, and to provide a repository of useful refereed papers. ' PUBLISH DATES Water Journal is published eight times per year: February, April, May, June, August, September, November and December. EDITORIAL BOARD Chair: Frank R Bishop; Dr Bruce Anderson, AECOM; Dr Terry Anderson, Consultant SEWL; Michael Chapman, GHD; Robert Ford, Central Highlands Water (rtd); Anthony Gibson, Ecowise; Dr Brian Labza, Vic Health; Dr Robbert van Oorschot, GHD; John Poon, CH2M Hill; David Power, BEGA Consultants; Professor Felicity Roddick, RMIT University; Dr Ashok Sharma, CSIRO; and EA (Bob) Swinton, Technical Editor.

AWA

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EDITORIAL SUBMISSIONS Water Journal welcomes editorial submissions for technical and topical articles, news, opinion pieces, business

Ozwater'1 OReport - see page 26

information and letters to the editor. Acceptance of editorial submissions is at the discretion of the editor and editorial board. • Technical Papers and Features Bob Swinton, Technical Editor, Water Journal- bswinton@bigpond.net.au AND journal@awa.asn.au Papers 3,000-4,000 words and graphics; or topical articles of up to 2,000 words relating to all areas of the water cycle and water business. Submissions are tabled at monthly editorial board meetings and where appropriate are assigned referees. Referee comments will be forwarded to the principal author for further action. Authors should be mindful that Water Journal is published in a 3 column 'magazine' format rather than the full-page format of Word documents. Graphics should be set up so that they will still be clearly legible when reduced to two-column size (about 12cm wide). Tables and figures need to be numbered with the appropriate reference in the text e.g. see Figure 1, not just placed in the text with a (see below) reference as they may end up anywhere on the page when typeset. • Industry News, Opinion pieces and Media Releases Helen Kelton, Editor, Water Journal- journal@awa.asn.au • Water Business and Product News Brian Rault, National Sales and Advertising Manager, Hallmark Editions - brian.rault@halledit.com.au

ADVERTISING Advertisements are included as an information service to readers and are reviewed before publication to ensure relevance to the water sector and objectives of the AWA. Brian Raul!, National Sales and Advertising Manager, Hallmark Editions - brian.rault@halledit.com.au Tel: +61 3 8534 5014 AWA BOOKSHOP Copies of Water Journal, including back issues, are available from the AWA Bookshop for $12.50 plus postage and handling. Email: bookshop@awa.asn.au PUBLISHER Hallmark Editions, PO Box 84, Hampton, Vic 3188 Tel: 61 3 8534 5000 Fax: 61 3 9530 8911 Email: hallmark.editions@halledit.com.au

OUR COVER Not one picture can portray the magnitude and success of Ozwater. The images on the cover represent some of the activities that constituted Ozwater'10, which took place in Brisbane from the 8-10 March 2010. The theme for this year "Achieving Water Security" brought together water professionals from all over Australia and the world, and presented key note speakers from Australia, Uganda, New Zealand , and the UK. See page 26 for full report.

water APRIL 2010 1


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Defining Catchment Management Arrangements Catchment management in each state has a significant role within source water protection and hence, the delivery of safe public drinking water. Within each state, legislation and government departments provide statutory powers, responsibilities and functions which support catchment management. During Ozwater'10, AWA's Catchment Management Specialist Network ran a workshop to develop diagrams representing the catchment management arrangements within each state and to discuss the similarities and differences between states. By undertaking this process, those attending the workshop identified the common issues and instruments which can be utilised for management purposes. The commonalities between states will provide the AWA Catchment Specialist Network with topics for further discussions and initiate collegial relationships into the future. The breath of scientific and management disciplines within the area of catchment management is diverse and includes water resources, development planning, environmental protection, management of parks and reserves, agricultural and pest animal and plant control. In addition to these areas, consideration should also be given t o public water supply, public health and price regulation. Ensuring a current and accurate representation of these functions and linkages within a state can be challeng ing. The diagrams developed will support the understanding of the stakeholder relationships for those working

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in this area. The workshop was attended by 60 delegates, with representatives from the majority of states. Delegates included consultants, water supply companies, research organisations, and local and state government. This enabled the development of catchment management diagrams relevant to source water protection for each state. Delegates discussed that, whi le each state works across all or many disciplines of catchment management to achieve source water protection, the focus on each varies considerably. In those states in which the source water catchment is predominately privately owned, the focus is on minimising risks from agricultural and urban land uses, while those in closed catchments (owned by the state) focus on the management of these lands, which may include National Parks, forestry or mining leases. While the diagrams focus on the statutory arrangements of states, the role and importance of non-statutory bodies was also considered. Simon Warner, Executive Officer of the South East Queensland Catchments Ltd, presented the role of his non-statutory organisation. Mr Warner explained that SEQ Catchments Ltd delivered a program of activities in accordance with the regions Natural Resource Management Plan, and provided a direct link to the rural commun ity. The program has evaluated sub-catchments to identify priority properties for catchment improvement, funded by SEQ Catchment Ltd and external partners. Catchment improvements, co-ord inated by non-statutory bodies such as South East Queensland Catchments Ltd, ensure that state government plans are implemented at the local level and contribute significantly to source water protection. Once delegates had completed the review of their state diagrams, the workshop turned its attention to discussing the similarities and differences between state arrangements. Overall, there are many similarities in the needs of catchment management and the available legislative tools and state government functions. The differences mainly occur at the application level and are dependent on state policy, risk profiles and the resources available for implementation. One difference was highlighted by speaker, Rob Franklin, General Manager Sustainability at Western Water, who discussed the role of Western Water in a planning decision in relation to a housing development adjoining a reservoir in their catchment. Under the Victorian Planning and Environment Act, 1987, Western Water has referral powers to consider development applications within its catchment and may recommend refusal, with which local government must comply. Alternatively, water utilities in other states, such as South Australia and Western Austral ia, do not have statutory powers under their Development Acts and so can only provide comment to council if they become aware of a development with potential to impact on drinking water supplies. Delegates discussed the advantages and limitations of such powers in source water protection. The AWA Catchment Specialist Network intends to use the workshop discussion as a foundation for continued networking and the development topics for more detail consideration by the network in the future. For more information on the Network please contact Christabel Ferguson or David Sheehan at networks@awa.asn.au.

regular features


demand management

SMART WATER METERING IN THE VICTORIAN URBAN WATER SECTOR P Harris, P Guttmann Abstract Major smart electricity metering programs are underway in Europe, North America and Australia that are designed to support the efficient use of resources and investment. The state of Victoria has mandated the deployment of Smart Electricity Metering (SEM) to all residential and small businesses by the end of 2013. In Victoria, the issues of climate change, population growth, security of water supply and empowering customers have encouraged consideration of extending the use of Automated Meter Reading (AMR) or Smart Water Metering (SWM) to the Victorian Urban Water Sector. It is expected that leveraging the SEM network would lower the costs for a SWM implementation. To facilitate the Victorian urban water sector's analysis of smart metering, the Department of Sustainability and Environment (DSE) commissioned Marchment Hill Consulting (MHC) to investigate, with industry collaboration, whether smart water metering could benefit the water industry and community. The study demonstrated, via a cost benefit analysis, t hat AMR and SWM capability could provide quantitative benefits. This paper describes the collaborative approach adopted in the study, t he key findings, and the study recommendations.

Background Introduction The DSE commissioned a study to investigate the potential costs and benefits of implementing AMR or SWM in the Victorian urban water sector. This study was driven by:

The urban water corporations across Victoria are coordinating further analyses. 44 APRIL 2010 water

• An opportunity for the water industry to leverage Victoria's investment in S EM;

• Increased interest of many utilities across the world in smart metering; • Addressing the variety of challenges arising from climate change, population growth and security of water supply; • Continuing to improve delivery of potable water and associated services, and enhance other water efficiency initiatives; • Empowering customers to better manage consumption and providing valuable demand information t o water sector stakeholders; and • Stimulating innovat ion in water management to achieve long term Victorian wat er industry reform objectives. The study recognised the environment in which the urban water sector across Victoria operated, considered the relevance of smart metering to a future Victorian urban water sector, and analysed the quantitative and qualitative costs and benefits of AMR and SWM to determine their net benefit. The outcomes of this study will be used to stimulate policy discussion and consideration of next steps amongst a broad stakeholder community.

Victorian Urban Water Sector The Victorian urban water sector is facing a set of issues which, in aggregate, are unprecedented and are making the entire sector an area of public and community focus. These events include: • A prolonged period of decreased rainfall and changes in its patterns, significantly diminishing reservoir storage levels; • Extended, severe water restrictions imposed as t he primary tool to manage supply shortages; • Debate on the effectiveness of current tariff pricing regimes at driving efficient water use; and

• Increased scrutiny on bulk water planning, water restriction policies and the price of water. These events have driven interest in identifying the potential for AMR or SWM to benefit the water industry and community.

The Victorian Electricity AMI Program Major smart electricity metering programs being conducted in Europe and North America provided impetus for the Federal and Victorian Governments to conduct studies to determine the potential net benefits from implementing SEM to approximately ten million electricity customers across Australia. The Victorian Government subsequently mandated t he deployment of SEM to all residential and small businesses in Victoria by the end of 2013, and a set of minimum Advanced Metering Infrastructure (AMI) Services t hat are to be made available to these consumers. The Victorian AMI program has been established to deliver on these mandates. These meters include functionality supporting a home area network which connects devices on customers' premises, and allows communications between these devices and the electricity distributor. In the context of the Victorian AMI Program, a water meter cou ld be considered as a home area network device. Therefore, t he opportunity exists for the water industry to leverage this investment to deliver benefits to the Victorian urban water sector.

Approach MHC performed both a quantitative and qualitative analysis of the potential costs and benefits of AMR and SWM. Information was gathered through a literature review of international AMR and SWM initiatives. The literature review was supported by consultation and interaction with the Victorian urban water sector. The DSE facilitated the collaborative involvement of the Victorian water corporations and

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demand management

9 s,te v,s,ts • Quant,tat,ve Costs and Benefits Gathering • Ouailtative Costs and Benefits Gathering

Figure 1. Study Approach. key industry stakeholders (representing policy, regu lation and consu mer advocacy) to achieve broad consensus of the study fi ndings through: • Data collection - a series of workshops and interviews were held to validate and update cost and benefit data sets prepared by MHC; • Peer review - industry and academic peer review was provided at several stages throughout the study to ensure the validity of findings; and • Formal comment - key stakeholders were invited to a number of industry forums to provide comment and feedback at key stages of the study. Feedback from water corporations, academics, government and consumer representatives were addressed in the draft and final study reports. The approach to the study is outlined in Figure 1.

Metering Options

The differences in accumulation, pulse and interval metering are depicted in Figure 2. The Victorian electricity industry has decided on time-based measurement of consumption using interval metering. This decision is based on historical practices in remote metering of electricity consumption, and for alignment to the measurement standards of the national electricity market, which is % hourly based. Interval metering is crucial to the national electricity market for the following reasons: • Electricity wholesale market trading is conducted on a % hourly tariff basis. Therefore, measurement of customer energy consumption on a % hourly basis will facilitate wholesale market trading activities; and

supply and demand during these critical peak periods. The above practices and drivers of interval metering are not universally established within the water industry: • Water wholesale market tradi ng does not exist; • Water can be stored; and • Given recent changes in cust omer behaviour and decreases in water consumption resulting from prolonged water restrictions, periods of peak demand are now less of a problem in the water industry.

AMR and SWM Definitions

• Electricity infrastructure is constrained, particularly during periods of extreme heat. Half hour consumption data allows the grid manager to balance

Driven by electricity investment, metering in the past decade has evolved from interval meters with simple communications, to advanced or smart met ering with an increased range of metering and communicat ion functionality.

Types of meters To date, water meters in Australia have been accumulation meters, yielding a single value per read and being suitable for AMR. SWM could record consumption data in two ways, either: • Pulse: a metered consumption data point is recorded when a certain vol ume is consumed (e.g. 1L, 10L, 100L, and the time and date); or • Interval: a metered consumption data point is recorded at specific time intervals (e.g. 15 minutes, 30 minutes, hourly, daily, and the volume of water consumed to that point).

46 APRIL 2010 water

Accumulation Water Meter

®

Single meter read every meter reading period measuring accumulated consumption

Pulse Water Meter

Pulse meter where consumption is recorded when a certain volume is consumed e.g. 1L, 1OL and is time stamped when that quantum is consumed

Interval Water Meter

Interval meter where consumption is recorded at specific time intervals e.g. 15 minutes, 30 minutes, hourly, daily (and the volume of water consumed to that point}

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technical features


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demand management Smart metering for the water industry would extend beyond the capability of AMR toward SWM. SWM is expected to, at a minimum, establish more granular (within a day) water usage data, two-way communications between the water utility and the wat er meter, and potentially communications to the customer.

Smart Water Metering Elements

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• Remote meter reads, scheduled and on-demand. With respect to a customer's household, SWM could enable: • Recording of water consumption from a pulse or interval meter on a weekly or daily basis; • Identification of network and household leaks; • Remote meter reads, scheduled and on -demand; • Notification of abnormal water usage; • Control of water-consuming devices within a cust omer's premise; and • Messaging to the customer. Figure 3 depicts the high level relationships between customers, the household (or metered site), and water corporations for AMR and SWM. Options for the implementation of AMR or SWM arise through choices on: • Customer communications: The method of communicating consumption information to customers: either in a historical manner through bills or in real-time across a HomeArea-Network (HAN) and In-House Display (IHD); and • Water corporation communications: The method and frequency of data collection: either by drive-by data

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collection or by a formal communications network.

AMR and SWM implementation options

Six alternative metering implementation options were considered for the quantitative and qualitative analysis. These options were: Implementation Option 1: Weekly AMR services. This approach uses drive-by data collection technology, and accumulation meter reads from AMRenabled meters. Data is collected on a weekly basis.

Meters are read using RF or similar technology. A data collection device is attached to a vehic le which drives past each AMR-capable meter. This is commonly called a 'garbage truck scenario', as these trucks travel the routes likely to be required for meter reading on a regular weekly schedule. Only accumulation meter reads are collected (similar to what is currently co llected today). Th is reduces the costs associated with storage of data, before and after collection. Implementation Option 2: Weekly pulse meter data collection. This approach uses drive-by data collection technology and pulse meter data reads. Data is collected on a weekly basis. Meter reads are collected using RF or similar technology. Pulse metering allows the water corporation to accurately identify water consumption patterns. Pulses are configurable in discrete quantities (typically 1L, 1OL, 1OOL, et c) and a single pulse is generated when this quantity of water is consumed. Data logging connected to the meter records the date and time of each pulse generated by the meter.

As with Implementation Option 1, a device is attached to a vehicle which collects data as it drives past each pulse

meter. Collection of pulse meter data can approximate time-of-use metering through mapping the time-stamp of each pulse into discrete time intervals. Implementation Option 3: Weekly pulse meter data collection plus in-house display. This approach uses the same metrology and collection mechanism as Implementation Option 2, but includes a ZigBee™ commun ications module (or similar) in each meter to allow connection and delivery of meter data to an in-house communications device. The capabi lities provided to water corporations are the same as Implementation Option 2.

In addition, the customer can view unvalidated metering data directly from their meter, and use this data to make informed choices concerning their water usage. Implementation Option 4 : Daily pulse

meter data collection using electricity AMI plus in-house communications. This approach uses the same metrology as Implementation Option 2, however, data is collected by accessing the Victorian electricity AMI networks (operated by electricity distribution businesses). Under an Order-in-Council, the Victorian electricity distribution businesses are required to install an AMI communications network and provide a SEM for all small electricity customers (both residential and com mercial) in Victoria. The SEM contains ZigBee™ communication capability which potentially allows connection to other ZigBee™ enabled devices, including water meters. This approach assumes that commercial agreements between the water corporations and electricity distribution businesses exist to allow the water corporations to access the electricity AMI commu nications network , in order to collect water meter data and send messages to their customers.

technical features


demand management Using this communications network, collection of pulse meter data can occur as often as every day. The water corporation and the electricity distribution businesses would agree an electricity AMI network access fee for the daily use of th is service (determination of the magnitude of the network access fee was outside the study scope). Collection of metering data will require each of the water corporations to build an interface to at least one electricity distribution business. As an alternative option, creation of a new water meter data management business that can collect metering data from the electricity distribution businesses on behalf of the water corporations is possible (the cost benefit impacts of this alternative option were not considered within this study). Under this implementation option, the water corporation can send commu nications to cust omers (i.e. for improved management of network outage periods, water quality alerts, water usage analytics and alerts, customer education, etc), and customers can display unvalidated metering data from their wat er meter via the electricity AMI meter to make informed choices concern ing their water usage. Implementation Option 5: Daily Interval Meter Data Collection using electricity AM I plus in-house communications. This approach uses the electricity AMI communications network (including ZigBee™ enabled electricity meters) to communicate to an interval data enabled water meter. The water meter measures the water consumption in a specified (and configurable) period such as 30 minutes, 1 hour or daily. Using ZigBee™ communication and the electricity distribution businesses AMI commun ications network, collection of interval meter data can occur as often as every day. Like Implementation Option 4, this approach assumes that commercial agreements exist between the water corporations and electricity distribution businesses to allow the water corporations to access the electricity AM I communications network to collect water meter data and send messages to their customers.

Under this implementation option, the wat er corporation can send communications to customers, and customers can display unvalidated metering data to make usage decisions.

Results

Implementation Option 6: Daily Interval Meter Data Collection using water AMI plus in-house communications. This approach uses a standalone water AMI network to provide daily interval water metering data to water corporations. water AMI networks could be built by individual water corporations and operate independently of all other AMI networks. Alternatively, a shared approach to construction of a water AMI network involving all water corporations could be considered. The differences in cost for each of the water corporations for an individual or shared AM I network approach are minimal.

Existing arrangements in the urban water sector form the base case against which the six implementation options have been compared. Quantitative Results

The study considered key cost and benefit elements including: meter procurement, installation and maintenance; meter reading and communications; IT systems; customer service; and asset management. The quantitative analysis performed in this study assessed the change in the cost and benefit elements, when compared to a 'Do Nothing' scenario. Assumptions: A large number of assumptions were made in developing the model.

The water AMI communications network will consist of a number of district concentrators, which collect data from water meters, and backhaul communications mediums to transfer the metering data to the water corporation. Construction and operation of such a network can be costly.

Certain assumptions that serve as input variables to the cost benefit analysis have a particularly strong effect on the result of the analysis. These include:

Meter data collection depends on the construction approach of the water AMI network. Individual AMI networks would lend themselves to independent meter data management functions. A shared AMI network cou ld lead to the creation of a shared water meter data management function. The cost benefit analysis in this study considers the individ ual water corporat ion approach to AMI network construction and meter data management.

• Cost of procuring meters; • Cost of scheduled and special meter reads; • Cost of IT system integration; • Projected increase in water prices; • Reduction in network leakage; and • Improvement in capital efficiency. Annual Net Benefits: With increasingly complex implementation options come increasing upfront costs and a

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Naturally, there will be increased meter data management requirements for collection of daily metering data and collection of internal metering data, when compared to collecting a smaller number of data points on a weekly basis. As per Implementation Option 4, col lection of metering data will require each of the water corporations to build an interface

Under this implementation option, the water corporation can send communications to customers, and customers can display unvalidated metering data to make usage decisions.

to at least one electricity distribution business for collection of meter data.

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Figure 4. Summary of Quantitative Analysis.

water APRIL 2010 49


demand management lengthening period before positive annual net benefits are realised. All of the implementation options selected eventually show positive annual net benefits by Year 9 at worst, or near the completion of the first meter roll-out. In Implementation Options 1 to 4, positive annual net benefits are realised by Years 5 or 6. By Year 9, the ongoing net benefits for Options 1 to 4 are broadly similar at $15m to $16.5m per year. In Implementation Options 5 and 6, the positive annual net benefits take longer to offset the heavier costs of interval metering and AMI capability - by Years 8 and 9 respectively. By Year 9, the ongoing net benefits for Options 5 and 6 are $6.5m and $0.5m respectively. NPV - Base Case: The relative NPV for Implementation Options 1 to 6 are represented in Figure 4. The cost of meters (including commun ications infrastructure), along with the cost of IT systems to support them, increases with :

• Transition from accumulation meters to pulse meters, and then to interval meters; and • Transition from drive-by meter data collection to use of the electricity AMI network (Options 4 and 5), and then to a standalone AMI communications network for water (Option 6). The benefits derived from reduced meter reading costs are greatest if an AMI network is used (Implementation Options 4 - 6). The benefits from improved asset management (including leakage detection and improved leak management) are roughly constant for all pulse or interval data implementation options. The key findings of the quantitative analysis were: • NPV positive outcomes can be demonstrated for Implementation Options 1 - 4; • Collection of interval metering data via Implementation Options 5 and 6 is NPV negative - the meters and associated systems are more expensive and the information is no more valuable than the pulse information; • Variations of up to 30% in the cost elements (i.e. cost of meters, scheduled and special meter reads, and IT systems) were examined in a sensitivity analysis. These variations do not significantly impact any base case NPV results; and

50 APRIL 2010 water

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6

Dall y Interval Meter Data Collection using Wate r AMI plus In House Comms

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Figure 5. Summary of Qualitative Analysis.

• Variations in the benefit elements (i.e. price of water, rate of reduction in network and household leakage, and degree of improvement in capital efficiency) were also examined. In extreme cases, these variations did drive negative NPV results for Implementation Options 2 - 4.

SWM may also provide additional customer and/or water corporation benefits through innovative water retail tariffs , support for more frequent customer billing, or enhancing customer relationship management. The benefits in these areas were small in t he current water sector environment.

In summary, quantitative analysis has shown that Implementation Options 1 - 4 appear to provide the most viable cases for further consideration by the Victorian urban water sector.

Additional qualitative benefits may be realised through social equity, enhanced water policy development and reduced carbon footprint.

Qualitative results

The study considered customer, societal, policy and environmental qualitative impacts. The most significant qualitative customer impact co mes through enabling SWM customers to make informed, proactive decisions about using water, in particular through the ability to track water consumption against mandated targets. A survey of Australian consumers (Newton et al. 2001) highlighted their belief that ensuring adequate supplies of water for both consumption and the health of the environment is the most important issue in society. The same survey showed that 42% of individuals cannot determine whether they are effective in reducing their own water usage. Therefore, consumers are likely to benefit from technology that allows them to monitor and understand their water usage. By providing consumer education it may be possible to establish a generational and societal change in attitudes towards water efficiency and consumption. The second most significant impact is in allowing customers with pulse or interval metering to identify and rectify household leakages sooner than is possible with accumulation metering.

The aforementioned customer impacts applied in Implementation Options 2 - 6 (refer Figure 5), where the availability of more frequent pulse or interval data would allow customers to monitor their water usage and diagnose leaks. Providing information daily to the water corporation was also considered to improve benefits compared to a weekly basis. Accordingly, qualitative benefits increased progressively between Implementation Options 2 and 4 and then remained the same for Imp lementation Options 5 and 6.

Conclusions The DSE successfully facilitated the col laborative involvement of the Victorian water corporations and key industry stakeholders for data collection, peer review and formal comment to achieve broad consensus to the study find ings. The consolidated quantitative and qualitative results are contained in Figure

6. The desk top analysis has demonstrated that for a number of options, benefits exceed costs. Accordingly, there appears to be value for the Victorian urban water sector to further evaluate smart water metering. Importantly, such evaluation should not only develop the quantitative information available to hand , but also provide

technical

eatures


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demand management greater evidence of qualitative costs and benefits to improve understanding. On the basis of the quantitative analysis, it would appear that AMR services (Implementation Option 1) should be deployed. However, as demonstrated by the qualitative analysis, Implementation Option 1 would provide minimal customer, societal, policy and environmental benefits in comparison to the other SWM options. On the basis of the current costs of interval metering collection (including the cost of interval meters and the IT systems to support these meters) none of the SWM options involving the deployment of interval meters (Implementation Options 5 and 6) are warranted because the additional metering and IT system costs provide no additional qualitative benefit over pulse metering based SWM. Each of the SWM options involving pulse metering (Implementation Options 2, 3 and 4) warrant further detailed consideration by the water corporations. The NPV for each was positive in each case, and supported by qualitative benefits. Further, the sensitivity analysis for each of these implementation options

52 APRIL 2010 water

eekly

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2 Weekly

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Overall Quantitative Benefit (NPV) Overall Qualitative Benefit

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Figure 6. Consolidated Analysis. has demonstrated robust NPV values through variation of a range of input assumptions with respect to the: • Cost of procuring meters, scheduled and special meter reads, and IT systems; and • Price of water, the rate of reduction in network and household leakage, and the degree of improvement in capital efficiency. Given that the quantitative analysis was based on extrapolating the current sector environment over 30 years, and specifically excluded consideration of broader network and service enhancements, if further investigation of

these implementation options demonstrates a positive business case for SWM, then any consideration of cost and benefits of the implementation of such enhancements does not have to include SWM costs. Provided that any further analysis of the likely costs and benefits of Implementation Options 2, 3 and 4 continues to demonstrate a positive NPV, there is no need to consider the additional costs and benefits that would arise from the implementation of broader network and service enhancements, in any form, in the decision for whether or not to proceed with SWM.

technical features


Recommendations This study demonstrated that, on the basis of operational costs and benefits alone, the Victorian urban water sector should consider implementing SWM. However, ongoing industry support and additional information is required to ensure that any implementation delivers optimal benefits for customer, societal, policy and environmental consideration. An investment to deliver additional information on SWM wi ll help quantify the qualitative impacts and better define relative net benefits that could be achieved from each implementation option. The study recommended that in order to progress SWM in the Victorian urban water sector the following next steps be initiated: • Analysis of Pulse Base SWM - review the functionality, costs, and implementation models for successfully implementing pulse SWM; • ZigBeerM Smart Energy Profile - review and contribute to the development of Zig Bee™ as a potential communications protocol to support SWM; • Market Research - research the value that customers place on SWM and what their responses to different tariff pricing regimes might be; • Smart Water Metering Trials - commence coordinated SWM trials to validate the costs and benefits of SWM; • Policy Development - make available and use the data generated from market research , SWM trials or actual operation in the development of urban water policy to help address the variety of challenges faced with respect to climate change, population growth and security of water supply. A group representing the urban water corporations across Victoria is developing a plan for coordination of these next steps. MHC continues to take an interest in SWM and planning of the next steps beyond this study.

The Authors

Paul Harris (email paulharris@marchmenthill.com) is Managing Consultant with Marchment Hill Consulting, with thirty year's experience in electricity, gas and water, involved in studies with the Tasmanian, Victorian and Queensland Governments and water retailers.

Leading the world in the modernisation of Irrigation Infrastructure Rubicon is leading the world in the modernisation of irrigation systems. Total Channel Control• technology has set a new International benchmark of 90% distribution efficiency. The FlumeGate"' is the cornerstone of rec• and provides accurate flow measurement and control. Rubicon has worked with the University of Melbourne for over 10 years pioneering innovative approaches to water delivery technology. Rubicon is Motorola's Distribution Partner, offering MOSCAD and ACE RTU solutions for management and control of Water and Wastewater for urban and rural Utilities. • SCADAConnect"' • FlumeGate'" • SlipGate'" • SolarDrive'" • Total Channel Control• (TCC)• • FarmConnect'" • Australian Premier Distributor for Motorola MOSCAD and ACE.

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References Newton Wayman Chong & Associates, 2001 , System Security Standards Study Group: Customers Value Study - Quantitative Stage - A Research Report.

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~ r e f e r e ed p a p e r

managed aquifer recharge

THE PATHWAY FROM BOUTIQUE TO MAINSTREAM WATER SUPPLY P Dillon, D Page, J Vanderzalm, S Toze, J Ward Abstract Managed aquifer recharge (MAR) has been in continuous use in Australia for more than 40 years. Used to supplement groundwater supplies of irrigation water on the coastal delta of the Burdekin River, Queensland in the 1960s it was not until 1992 that it was first applied intentionally to developing supplies in urban areas, when stormwater harvesting for non-potable use began at Andrews Farm, South Australia. Since then, uptake has been geographically patchy, but where its value has been discovered, growth has followed quickly (Figure 1). The City of Salisbury is a stellar example where stormwater harvesting and aquifer storage and recovery is now providing 7 GUyear and 20 GUyr is targeted within a few years. At a larger scale the Water for Good Plan of the SA Government calls for 60 GL of stormwater harvesting via MAR in Adelaide and 15 GUyr in reg ional SA by 2050 (SA Government 2009). In addition, MAR planning and pilot projects are underway in three states (SA, WA, Vic) for subsurface storage of recycled water derived from sewage treatment plants, with a combined capacity of more than 30 GU yr. This paper outlines recent developments/initiatives that facilitate the national uptake of MAR and aims to answer the following questions. Why has the gestation period of this 'green' technology been so long before reaching its current popularity? And is this a passing fad or is it here to stay?

Aust ralian Guidelines for MAR The year 2009 was a turn ing point for the application of managed aquifer recharge (MAR) in Australia, and by example, elsewhere. Of primary importance, in August the Australian Guidelines for Managed Aqu ifer Recharge were published within the Australian Guidelines for Water Recycling as document 24 in the National Water Quality Management Strategy (NRMMC-EPHC-NHMRC 2009). These guidelines address protection of human health and the environment within a risk management framework consistent with ot her NWQMS guidelines. This bridged a gap for proponents and

54 APRIL 2010 water

Types of MAR In use In 2008 Northern Territory

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0

ASR reclaimed water

e ASR stormwater

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_.. Reservoir release South

Brisbane

O Pond infiltration 0 Soil aquifer treatment

0 Management of Aquifer Recharge in Australia

+ Melbourne

0

Teamanla~

Infiltration gallery (reclaimed water) Infiltration gallery (stormwater) ASR investigations

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Figure 1. Locations and types of managed aquifer recharge (MAR) in Australia in 2008 (from Dillon et al 2009). ASR = aquifer storage and recovery. regu lators of MAR projects, by providing a consistent scientific approach to regulation on water quality and environmental issues associated with MAR (Di llon 2009). Some states (SA and Vic) have already produced codes of practice under their environmental regulations that requi re proponents to adhere to the national MAR guidelines. Further assistance is being provided via a series of workshops (see Box).

MAR within Water Resources Management Policy Secondly, a document was produced for the National Water Commission to lay out a robust policy framework for MAR. Although the SA Government is well advanced in taking account of MAR in water allocation policies for individual projects, other jurisdictions had only just begun to consider the issues. These range from ownership of stormwater and rights to harvest, to arrangements for water banking and transfer of groundwater credits. As MAR develops further, there will be a need for holistic catchment- and basin-wide policies to enable MAR to contribute to efficient,

A passing fad or

here to stay?

equitable and secure economic development and environmental protection and restoration. The policy framework, reviewed by members of the National Groundwater Committee, is based on the National Water Initiative and the adoption of entitlements, allocations and use conditions for the taking of water for recharge, recharging aquifers and recovering water (Ward and Dillon 2009). Assistance regarding the MAR policy framework will also be provided t hrough workshops (see Box).

Knowing Where MAR can be Done Th irdly, the National Water Commission identified that knowledge of suitability of aquifers for MAR was needed to enable uptake. Unless there is an aquifer capable of accepting, storing and yielding wat er, MAR is not possible. Each State requires drillers to report basic hydrogeological information to a department responsible for maintaining a database. However, further simple interpretation is required to evaluate the prospects for water banking at any location. Previous studies in Perth, Adelaide and Melbourne have produced maps of the potential for subsurface st orage (see references in Dillon et al 2009). However

technical features


managed aquifer recharge

~ refereed paper

very little else of the cou ntry had been mapped at a scale that was likely to be useful for identifying opportunities for MAR. As part of the National Water Commission 's Raising National Water Standards initiative SKM and CSIRO undertook evaluations in South East Queensland (Helm et al 2009a) and on the central coast of NSW (Molloy et al 2009). Other work supported by NWC included assessments for more than 100 regional towns and cities, assessments for agriculture and feasibi lity studies in Sydney and Canberra, in total valued at about $6M (NWC 2009). A reassessment for Adelaide was also completed accounting for the availability of open space for surface detention storage prior to recharge of stormwater (Helm et al 2009b).

How MAR Compares with Alternative Supplies It was also identified that information on the economics of MAR in relation to alternative water supplies such as seawater desalination wou ld foster consideration and hence uptake. Consequently the National Water Commission published a lay-persons' guide to MAR as Waterlines Report #13 (Dillon et al 2009) including a review of the economics of operating projects. This showed that stormwater harvesting and aquifer storage and recovery (ASR) in SA occurs at less than half the levelised unit cost of desalination with only 3% of the greenhouse gas emissions. In places where storage is important, the use of aquifers for storage can be as little as 2% of the costs of the equivalent volume of storage tanks (Figure 2).

Figure 2. This ASR well in the foreground stores and recovers treated drinking water using the underlying aquifer at a depth of 100 to 130 m. The volume stored below ground during the low demand period and recovered in the high demand period at Cocoa, Florida, USA, is ten times the volume of the two tanks behind. The unit storage cost of ASR was less than 2% of the alternative cost of constructing additional tanks (from Dillon et a/2009). Other benefits include the reduced land area required, the ability to store locally rather than pumping at high-rate to dams outside the city, and the absence of evaporative losses, algal problems and mosquitoes. The water quality protection barrier that aquifers provide in water recyc ling (see e.g. Kazner 2010, Page et al 2010, Toze and Bekele 2010) is also valuable along with the public confidence this endows. Hence, determining the presence of a suitable aquifer can have a large impact on the economics of water supply and security of a region.

Levelised cost ($/KL) Including harvesting • Excluding harvesting

3.00 I!)

....I

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--

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1§1

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0.000

100

200

300

400

2000

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Figure 3. Levelised cost of water is shown in relation to the size of the stormwater aquifer storage and recovery (ASR) project. Economies of scale are observed between 15 and 75 ML/yr, and costs are relatively stable at larger volumes. Water harvesting costs (construction of wetlands and drain diversions) could not be separately identified at three sites. In all cases land cost is excluded as the wetland was required for flood mitigation. (Sources of data were SKM, AGT and City of Salisbury) (from Dillon et al 2009).

Drawbacks and Economic Size Subsurface storage also has limitations such as the constraints on rates of infiltration or injection and extraction imposed by local geological strata. For example, in some aquifers with st eep hydraulic gradients and containing brackish groundwater, recovering the stored fresh water cou ld be problematic. The aquifer itself, depending on its mineralogical composition, can in some circumstances deteriorate the quality of stored water (Vanderzalm et al 2009). However these and other issues are covered in the MAR guidelines, and require localised hydrogeological and water quality investigations to evaluate the measures required t o ensure safe and effective operation. Due to the cost of these investigations, in general ASR systems need to be larger than around 50 MUyr to be economically attractive. This is not to dismiss small scale systems, such as domestic roof rainwater recharge for irrigation supplies, that have inherently low risks where aquifers and their existing uses are well understood. The MAR guidelines address such cases through a simplified risk assessment process that does not inhibit viability.

Current Status of MAR Although Australian MAR started in agricultural supplies, the recent restrictions on supplies of urban water, higher price paid for supply, and the availability of urban runoff and treated sewage and water reclamation plants has led to the bulk of recent MAR projects

water APRIL 2010 55


~ refereed paper

managed aquifer recharge being in urban areas. Urban MAR supplies have been produced in three states and the Northern Territory and growth is expected to exceed the current Australian rural irrigation MAR supply of 45GUyr within a few years. However, where aquifers are unconfined, soils are permeable, and water is available to allocate to diversion for MAR, it is also likely that rural MAR could expand to increase security of rural groundwater irrigation supplies. The current costs of pond infiltration in the highly favourable conditions of the Burdekin Delta are $0.07/kl compared with in the order of $0.20-$0.40/kl for ASR with reclaimed water and $1.12/kl (capital $0.84/kl and operating expenditure $0.28/kl) average for stormwater ASR at eight sites in semi-arid Adelaide (Figure 3), where lack of availability of runoff limits asset utilisation.

Bright Future for MAR Making use of natural assets for water storage and supplies makes sense, whether in a developing or developed country. Why pay to construct a storage if you already have one? However exploiting storage capacity of Stateowned aquifers is not free, because there are investigation costs to determine viability and risks and how to manage them effectively. The Australian MAR Guidelines now provide proponents, regulators and the public the means to be confident in the sustainability of MAR operations. With increasing adoption of water sensitive urban design (WSUD) the quality of urban stormwater and the quantity harvestable will improve, and with tightening requirements on urban coastal water quality, investments in wastewater reclamation and recycling will make more water available for use and for storage to address counter-cyclic demand. The need for adaptation to climate change by replenishing depleted groundwater storages and freshening of brackish aquifers, safe from evaporative losses and protecting against rising sea levels using carbon-frugal technologies is intuitive. Local demonstration projects with technical and cost information made publicly avai lable are also central to further uptake of MAR, as with any emerging technology. Existing successful projects by innovative organisations and consortia should help to build confidence in market-follower organisations. CSIRO has assisted by conducting research in innovative projects or on project review or advisory committees, and disseminating new knowledge by leading

56 APRIL 2010 water

Workshops on support for implementing MAR Guidelines and policy framework - Autumn 2010 CSIRO has prepared for National Water Commission a set of case studies of demonstration projects with their risk assessments as would be required if those projects were developed in accordance with the Guidelines. This was prepared in consultation with project partners and the working group that oversaw the development of the MAR Guidelines and will be released in a series of workshops in autumn 2010 in states and territories that express interest in running a workshop. This document, which was requested at several public consultation meetings concerning the draft MAR Guidelines, is intended to be a companion document and support to the MAR Guidelines, to help proponents and regulators. Nine case studies are documented covering: • domestic rainwater ASR • stormwater ASR (2 sites) • reclaimed water ASR • reclaimed water infiltration galleries • reclaimed water soil aquifer treatment (intermittent infiltration) six national workshops on MAR. Several consulting organisations are developing significant portfolios of MAR projects demonstrating broad competence in investigations, design and construction. Several water utilities and local government bodies are gaining experience in operating MAR systems. Regulators and water resources managers in a number of jurisdictions have developed the knowledge to be competent in governance of MAR. Hence there is no substitute for the impact of demonstration projects on acceptance of MAR.

Remaining Barriers However more needs to be done to better integrate MAR into water resources management policies. Trad ing of groundwater credits, or finding ways of c onnecting recovered water to existing water reticulation systems will allow many more possibilities than the current emergent MAR which so far occurs only where the trinity of demand for water, temporary surface water excess and suitable aquifer storages coincide. Moves to recognise the connectedness of surface water and groundwater at an institutional level will help to unify

• groundwater ASR for drinking supplies • stormwater aquifer storage, transfer and recovery (ASTA) for drinking supplies • initially unintentional stormwater ASTA for drinking supplies (operational) In addition workshops on a robust policy framework for MAR are offered to coincide with the above workshops on MAR Guidelines and case study risk assessments. This will be an opportunity for water resources managers to discuss in-depth the suitability of such a framework and the possible pathways to implementation of MAR policies in those State, Territory, catchment or basin jurisdictions requesting such a workshop. Individuals and organisations wishing to express interest in attending a workshop, for MAR Guidelines support and/or for MAR Policy framework, are invited to register their interest with Vicky.Mackenzie@csiro.au (ph 08 8303 8425).

fragmented water resources management responsibilities within jurisdictions. Also , where a single utility is responsible for mains water, sewage and stormwater, integrated management of these three resources can be more easily implemented. Training programs for MAR operators will also be needed to ensure that systems are operated as intended, and contingencies are safely addressed. Further research on biogeochemical processes in aquifers including those affecting the fate of pathogens and trace organics and on clogging will help to widen the range of usable aquifers and reduce costs by tailoring engineered water t reatments to the aquifer and end use of water. Further progress with the National Water Initiative will see a holistic approach to developing futu re water supplies taking account of all the environmental, social and economic costs and benefits of each alternative. Under triple bottom line evaluations the environmentally friendly aspects of MAR will advantage it in relation to coastal water quality, greenhouse gas emissions, aquifer restoration and urban amenity. As information on the economics of MAR is

technical features


[lil

managed aquifer recharge

ref ereed paper

heard, aquifers will become better known, and where they are suitable MAR will become a mainstream contributor to water supplies.

International Information on MAR The International Association of Hyd rogeologists has a Commission on Managed Aqu ifer Recharge (IAH-MAR). This conducts international symposia on average every three years; the next one being in Abu Dhabi, 8-13 October 2010 (www.ismar7.org). The IAH-MAR website (www.iah.org/recharge) contains reports and brochures on MAR, a grey-literature dat abase, information about relevant conferences, innovative projects, research, and registration for a free email list to stay in touch with developments in this field .

Acknowledgments The work reported here was supported by t he National Water Commission through the Raising National Water St andards Program in the project entitled 'Facilitating uptake of recycli ng of st ormwater and treated effluent via aquifers', a project conducted by CSIRO with t he opportunity assessment component led by SKM.

The Authors

Ors Peter Dillon, Declan Page, Joanne Vanderzalm, Simon Toze and John Ward contribute to CSIRO Water for a Healthy Country National Research

Flagship, Urban Water Theme in the 'Stream ' Water Recycling and Diversified Supplies, led by Peter Dillon. Peter, Declan and Joanne are members of CSIRO Land and Water at the Waite Campus, Adelaide, Simon is with CSIRO Land and Water in St Lucia, Brisbane and John is with CSIRO Sustainable Ecosystems at St Lucia. Contact: Peter.Dillon@csiro.au, 08 8303 8714.

References Dillon, P. (2009). Groundwater Replenishment with Recycled Water - An Australian Perspective. Ground Water News and Views, Groundwater Journal, 47(4) 492-495. Dillon, P., Pavelic, P. , Page, D., Beringen H. and Ward J. (2009). Managed Aquifer Recharge: An Introduction, Waterlines Report No 13, Feb 2009. http://www.nwc.gov.au/www/html/996mar-an-introduction - -report-no- 13- feb2009.asp Helm, L. , Molloy, R., Lennon, L. , and Dillon, P. (2009a). Facilitating Recycling of Stormwater and Reclaimed Water via Aquifers in Australia - Milestone Report 3.3.2 - South East Queensland Opportunity Assessment. Water for a Healthy Country Flagship Report to National Water Commission, Apr 2009. http://www.clw.csiro.au/publications/waterfora healthycountry/2009/wfhc-MAR-policy-designmilestone3.3.2.pdf Helm, L. , Molloy, R., Lennon, L., Clark, R., Barton, A. and Dillon, P. (2009b). Facilitating Recycling of Stormwater and Reclaimed Water via Aquifers in Australia - Milestone Report 3.3.3 Potential for Harvesting Adelaide Stormwater via Managed Aquifer Recharge: Preliminary Assessment of the Influence of Urban Open Space. Water for a Healthy Country Flagship Report to National Water Commission, Apr 2009. http://www.clw.csiro.au/ publicat ions/waterfora healthycountry/2009/wfhc- MAR-policy-designmilestone3.3.3. pdf Kazner, C. (201 0), Reclaim Water: Research Results, Water 37(2) pp 62-66. Molloy, R., Lennon, L. , Helm, L. and Dillon, P. (2009). Facilitating Recycling of Stormwater and Reclaimed Water via Aquifers in Australia

- Milestone Report 3.3.1 - NSW Central Coast Opportunity Assessment. Water for a Healthy Country Flagship Report to National Water Commission, Apr 2009. http://www.clw.csiro.au/pu blications/waterfora healthycountry/2009/wfhc-MAR-policy-designmilestone3.3.1.pdf NRMMC-EPHC-NHMRC (2009). Australian Guidelines for Water Recycling, Managing Health and Environmental Risks - Managed Aquifer Recharge. Natural Resource Management Ministerial Council, Environment Protection and Heritage Council National Health and Medical Research Council. Aug 2009, 237p. http://www.ephc.gov.au/taxonomy/term/39 NWC (2009). National Water Commission Annual Report 2008/09. Appendix D. http://www.nwc.gov.au/www/ html/2491annual-reports.asp?intSitelD=1 Page, D., Dillon, P., Toze, S, Bixio, D., Genthe, B., Jimenez-Cisneros, B. , Wintgens, T. (2010). Valuing the subsurface pathogen treatment barrier in water in recycling via aquifers for drinking supplies. Water Research 44, 184152. SA Government (2009). Water for Good - SA's water management plan to 2050. http://www.waterforgood.sa.gov.au/2009/06/ water-for-good-sas-water-management-planto-2050/ Toze, Sand Bekele, E. (2010). Recycling Water via Infiltration Galleries in Urban Environments, Water 37(2) pp 58-61. Vanderzalm, J. , Sidhu, J. , Bekele, G-G., Pavelic, P., Toze, S., Dillon, P., Kookana, R. , Hanna, J., Barry, K., Yu, X., Nicholson, B. , Morran, J., Tanner, S. and Short, S. (2009). Water Quality Changes During Aquifer Storage and Recovery. Water Research Foundation. Denver, USA. Ward, J. and Dillon, P. (2009). Robust Design of Managed Aquifer Recharge Policy in Australia. Report to National Water Commission. CSIRO, Water for a Healthy Country National Research Flagship Report to National Water Commission, Apr 2009. http://www.clw.csiro.au/ publications/waterfora healthycountry/2009/wfhc-MAR-policy-designmilestone3.1.pdf

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water APRIL 2010 57


~ ref ereed paper

managed aquifer recharge

RECYCLING WATER VIA INFILTRATION GALLERIES IN URBAN GROUNDWATER S Toze, E Bekele, Z Leviston, B Patterson Managed Aquifer Recharge (MAR) is a technique that has great potential for assisting the uptake of water recycling in urban environments. To further determine the applicability of MAR in urban environments a research project was undertaken on the Perth Coastal Plain to cover a number of issues considered important for MAR, namely setting up and operating a MAR scheme; the persistence of trace organics and enteric pathogens in groundwater; the social attitudes to water recycling, in particular those relating to MAR; and the exposure risks from pathogens and trace organics in water recovered from MAR schemes. This paper provides a summary of the research findings. The full report can be obtained from the CSIRO publications web site (Toze and Bekele, 2010).

Design and Operation of Infiltration Galleries and Water Quality Changes This research focused on investigating the ability to recharge treated wastewater to a superficial aquifer using infiltration galleries and the movement of the recharged water through the aquifer; assessing changes in the quality of the recharged water during its residence in the aquifer; and identifying any management and operational issues that might be encountered in operating such a MAR scheme. The scheme was operated on the Floreat site of CSIRO, in a shallow unconfined sand-limestone aquifer. (Toze, Bekele, 2009). While there is a range of MAR methods and types of source water, it was decided that infiltration galleries using secondary treated wastewater was the most appropriate method to test for the current project. Infiltration galleries have the advantage of being cheaper, less sophisticated to operate and are potentially less prone to clogging than well injection systems. Infiltration galleries also have potential advantages over MAR systems that use ponds (such as pond infiltration and soil aquifer

58 APRIL 2010 water

TOP VIEW

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4m

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Figure 1. Schematic of the covered infiltration galleries as originally installed at the Floreat site.

treatment methods) in that they are located below ground and thus do not take up the valuable ground area that pond systems would (Figure 1). There is also considerably less pot ential for unsupervised access to the recharging water by the community, domestic animals or w ildlife. In addition, the lack of exposed water means that there is no chance for mosquito breeding in the ponded water prior to recharge . The research outcomes demonstrated that treated wastewater can be efficiently and sust ainably recharged to the superficial aquifer in urban areas on the Swan Coastal Plain using infiltration galleries. Due to clogging , the use of

Sustainable recharge in shallow aquifers can be achieved.

gravel-filled trenches was not as effective or sustainable as the Atlantis Leach SystemÂŽ for infiltrating large quantities of secondary treated wastewater. Using a three-dimensional MODFLOW-MODPATH simulation, an estimation of the minimum residence time in the saturated zone at the Floreat Infiltration Galleries site was determined to be approximately 70 days between the galleries and the extraction bore. Based on a conservative transport model calibrated with chloride data, the estimated maximum proportion of infiltrated water in the water recovered at the extraction bore (with a pumping rate of 250 KUday) was 20%. A comprehensive investigation of water quality during recharge and movement through the aquifer indicated that changes occurred for most of the tested analytes in the recharge water. Testing of the decay of selected enteric

technical features


~ ref ereed pape r

managed aquifer recharge

microorganisms demonstrated that the aquifer had a treatment capacity to remove pathogens (Figure 2). In addition, extensive sampling of the recharged water/groundwater from monitoring bores along the transect of the MAR scheme showed that enteric viruses and bacteriophage could not be detected in the aquifer further than 1 metre from the infiltration galleries. Removal of nutrients and trace organics during passage through the unsaturated zone was assessed by comparing the concentrations in the treated wastewater entering the infiltration galleries with water sampled from monitoring bores located around the galleries. Significant declines in phosphate were ob served within a few metres of the inf iltration galleries. There was no evidence of attenuation or removal of nit rate due to the aerobic nature of the aquifer preventing denitrification from occurring. The concentrations of the pharmaceuticals carbamazepine and oxazepam, and to a lesser extent temazepam, were observed to reduce in monitoring bores down-gradient from the recharge source, possibly d ue to dilution. Based on mass recovery rates , no degradation of these compounds was observed. The concentrations of these compounds in the recycled water were only in lg/L concentrations which were assessed be not be of concern for human health when the water is to be used for nonpot able purposes. The assessment of operational and management requirements of MAR schemes, such as infiltration galleries, using treated wastewater as a source water identified a number of issues for consideration. It was shown that the Atlantis Leach SystemÂŽ gave a superior performance to the use of gravel in the co nstruction and operation of the infiltration galleries indicating t hat care is needed in the original design of MAR syst ems, with the preliminary t esting of any previously untested systems and d esigns being strongly recommended. Ongoing monitoring of the performance of the infiltration gallery system determined that monitoring various parameters and analytes and undertaking targeted hydrogeological experiments were invaluable in gaining a better understanding of t he movement of t he water through the unsaturated zone and the aquifer. Other issues relat ed to factors such as the initial design and set up of the MAR schemes; the reliability of the supply and the

(a)

0

2

4

6

8

10

Time (days)

(b)

0

1+rrTTTT~TTT'"TTT'"TTT"'"TTT"l~'TT"n'"'TT'.......,.........,

0 5 10 152025 30 35 40 45 Time (days)

Figure 2. Examples of assessment of pathogen decay at the infiltration gallery MAR scheme where (a) is E. coli, and (b) is Cryptosporidium sp oocysts.

influence this may have on the day-today operation of the MAR scheme; the influence of dissolved iron on the quality of the recovered water; the appropriate installment and protection of t he pipe system delivering the treated wastewater to the infiltration galleries; the clogging potential of the infiltration galleries and the associated appropriat e monitoring techniques; and the appropriateness of the monitoring and analysis equipment used to monitor the operation of the MAR schemes were also fou nd to be important.

Fate of Trace Organics Using Laboratory Column Experiments The presence of trace organics in the water used as a source for recharge and their behaviour and fate in the aquifer was studied to determine the potential persistence of a range of trace organics under different conditions expected to occur in the d ifferent aquifers on the Swan Coastal Plain. The fate of specific trace organic compounds was investigat ed under laboratory cond itions in large-scale columns. Experiments were conducted testing different aquifer sediments, redox conditions and types of recharge water. Nine trace organic compounds used in the research were bisphenol A (BPA) , 17~-estradiol (E2), 17a-

ethynylestradiol (EE2), oxazepam (OXAZ), carbamazepine (CARS), N-nitrosodimethylamine (NOMA), Nnitrosomorpholine (NMOR), iohexol (IOX) and iodipamide (IDP). The behaviour and persistence of each trace organic under the different redox conditions and water types in the Leederville and Spearwood sediments were assessed based on their chemical retardation coefficient (R) and degradation half-life, determined from the experiment al data. In Spearwood sediment, which has a low organic carbon content, none of the trace organics were retarded, indicating that these compou nds would travel at near groundwater velocities in the Tamala aquifer. Degradation of E2, EE2, SPA and IOX was observed , however the other t race organics tested were not degraded. Therefore, concentrations of the nitrosamines (NOMA and NMOR), pharmaceuticals (OXAZ and CARS), and the x-ray contrast medium (IDP) were determined unlikely to be substantially reduced during MAR under these aquifer cond itions. In contrast, in the relatively high organic carbon content Leederville sediment, all the trace organics tested except the nitrosamines and IOX showed substantial sorption to the aquifer material. This suggest s that these trace organics would have slow migration rates in the Leederville aquifer. Rapid degradation of E2, EE2, BPA and IDP were observed in the col umns containing the Leederville aquifer material, however, none of the other trace organics were degraded. Therefore, concentrations of the nitrosamines, pharmaceuticals, and IOX are unlikely to be reduced substantially during aquifer passage associated with MAR in the Leederville aquifer. Geochemical changes as a resu lt of the injection of aerobic reverse osmosis (RO) treated water into the red uced Leederville sediment were also observed. These changes included rapid oxygen consumption with the production of sulphate (suggesting pyrite oxidation); and increases in selected anions and cations, suggesting mineral dissolution of possibly gypsum, dolomite and ankerite. Despite these observed geochemical reactions, however, no increase in the concentration of heavy metal(loids) was observed. As determined in the infiltration galleries, nitrate is persistent in the

water APRIL 2010 59


managed aquifer recharge superficial aquifer due to the aerobic nature of the aquifer. Experiments undertaken in the large-scale columns investigating the potential for inducing denitrification within the recharge zone of MAR schemes to remove the nitrate from the recharged water demonstrated that removal of nitrate from the recharged water was possible during aquifer passage through the use of ethanol carbon-dosing. An additional benefit of inducing denitrifying conditions using the ethanol dosing method was that t he reducing conditions resu lted in enhanced degradation of iodipamide (IDP).

Community Attitude and Behaviour Research Until recently, very little has been known about the social acceptability of recycling water via MAR. As a result, research was done which explored community perceptions, attitudes and intended behaviour towards MAR for a range of fit-for-purpose uses. An initial research project had shown that the vast majority of those surveyed supported MAR for the recycling of wat er in general (Po et al., 2005), however, less was known about how this support could change if the recycled water used had been treated to potable standards for high level usage such as indirect potable recycling. It was considered that testi ng community attitudes to these high end uses would be useful to further test the preliminary findings of Po et al. (2005) on the factors driving community acceptance of recycling via MAR and the efficacy of the preliminary models. To test these models the research was undertaken via a behavioural modelling survey of 500 Perth householders on their acceptance of MAR for assisting indirect potable reuse. The results obtained from the survey found that there was a high level of support for MAR for the recycling of water. The results also showed however, that while over half of respondents intended to support a MAR scheme in Perth, a significant proportion (one-fifth) of this half were not forming strong convictions about the scheme, expressing moderated responses in relation to intended behaviour towards MAR. Approximately one-quarter of respondents gave responses that indicated refusal to support the scheme.

60 APRIL 2010 wat er

The results also showed that there were no statistically significant differences observed based on education levels, income levels, family unit and age. In contrast, the research showed that males' behavioural intentions toward the MAR scheme were significantly more positive than females. The resulting developed behavioural model showed that emotion and subjective norm had the strongest direct influence on intended behaviour in relation to an indirect potable MAR scheme. Fairness, trust, and perceived health and system risks also had significant influences. A notable exception was that knowledge consistently failed to contribute significantly to the prediction of intended behaviour. The social investigations have shown that there is a range of planning implications that are important to consider in relation to the potential introduction of MAR in urban environments such as Perth. These include dealing with the impacts of trust, risk and uncertainty; the importance of providing credible alternatives as well as information and discussion on the complexities relating to the different water recycling options available; the need for transparent and open decision-making processes; and ensuring that communities are involved in the decision-making processes.

Health Risk Assessment The health risk assessment research work investigated the human health risks of using recycled water via MAR for irrigation purposes. An initial assessment determined that while both microbial and chemical contaminants are major health concerns raised by the public for the reuse of recycled water, in the case of irrigation applications using water recovered from a MAR scheme, microbial hazards are the major concern. The microbiological risk was assessed using a Quantitative Microbial Risk Assessment (QMRA). This model used pathogen occurrence data in treat ed wastewater from the scientific literature, decay data from the in situ experiments at the infiltration gallery site, the hydrologeological assessment of residence times in the aquifer, and a number of d ifferent exposure scenarios involving irrigation to

[I]

refereed paper

determine the risk to human health. Based on the accept able risk standards in the Australian Guidelines for Water Recycli ng, the exposure risk for Cryptosporidium and rotavirus in the recovered recharged water was found to be marginally above the Guideline values for achieving an acceptable health risk under the experimental conditions used at the research infiltration gallery site. The QMRA modelling indicated that increasing the residence time of the water in the aquifer to approximately 150 days would enable the recovered water to meet the acceptable health risk standards for recycled wat er used for non-potable purposes. This research demonstrated that Quantitative Microbial Risk Assessment can be an effective method to assist in designing sustainable MAR schemes (Toze et al. 2010).

Conclusions The research undertaken has demonstrated that MAR can be successfully used in an urban environment such as Perth. Infiltration galleries are a MAR method that can successfully combine the advantages of surface infiltration along w ith the benefits of being below ground, thus preventing uncontrolled access. When appropriate materials are used to construct the infiltration galleries, the research has shown that sustainable recharge using recycled water can be achieved. Recycling water through the subsurface and through the aq uifer can improve the quality of the water and achieve recycled water that can be free of health risks to the community when used for non-potable purposes such as irrigation . Environmental risks can also be managed, however, the research demonstrated that it is very important to ensure that potential environmental hazards are assessed and MAR schemes such as infiltration galleries are designed appropriately to mitigate these hazards, achieve maximum sustainability and optimum water quality improvements. Finally, this research project has shown that using MAR as a mechanism to assist water recycling can receive community support. This support, however, is dependent on the processes involved being seen to be

technical features


transparent and open. In addition, the research has demonstrated that it is vital that the developers and operators of MAR schemes work to develop trust with the community.

Acknowledgments This project was made possible through funding from the WA Government Water Foundation, CSIRO Water for a Healthy Country Flagship and the Water Corporation of Western Australia. In Kind support was also provided by the research partners, CSIRO, Water Corporation, ChemCentre, Curtin University and University of Western Australia.

The Authors

Drs Simon Toze, Elise Bekele, Zoe Leviston and Bradley Patterson are all members of the CSIRO Water for a Healthy Country Flagship, Urban Wat er Theme. Simon , Elise and Bradley are also members of CSIRO Land and Water and Zoe is a member of CSIRO Sustainable Ecosystems. Simon is based at St Lucia, Brisbane whi le Elise, Zoe and Bradley are based at Floreat, Perth. They were the project leaders for the WA Water Foundation Project "Determining Requirements for MAR in Western Austral ia" and this paper is written on behalf of the research team (See the final report Toze and Bekele 2010 for full details on the project group).

References Po, M ., Nancarrow, B.E., Leviston, Z., Porter, N.B., Syme, G.J., and Kaercher, J.D. (2005) Predicting community behaviour in relation to wastewater reuse: What drives decisions to accept or reject? Water for a Healthy Country National Research Flagship, CSIRO Land and Water, Perth. Toze Sand Bekele E (2009) Managing Aquifer Recharge with Secondary Treated Wastewater. Water, 36, 2. March. Toze Sand Bekele E (2010) Determining R equirements for Managed Aquifer Recharge in Western Australia. WfHC Report http://www.csiro.au/ resources/Publications.html. Toze S, Bekele E, Page D, Sidhu J. Shackleton M (2010). Use of static Quantitative Microbial Risk Assessment to determine pathogen risks in an unconfined carbonate aquifer used for M anaged Aquifer Recharge. Water Research 44(4): 1038- 1049.


managed aquifer recharge

RECLAIM WATER: RESEARCH RESULTS C Kazner This article is a precis, prepared by the Editor, of the paper presented by Kazner et al at the AWA Water Reuse Conference, Brisbane, September 2009. The original contains far more detail, and cites 35 references.

Managed Aquifer Recharge: A European Commission Project

Table 1. Water reclamation schemes investigated in RECLAIM WATER. Test Site

Managed Aquifer Recharge (MAR) is receiving growing attention in water recycl ing because it features advantages such as storage capacity to buffer seasonal variations of supply and demand, additional natural treatment as well as mixing with natural water bodies which promotes the acceptance of further uses, particularly indirect potable use. For urban supply there is concern about potential presence of microbial pathogens and trace organics such as pharmaceuticals and endocrine disruptors. The technology for purific ation of the wastewater and the extent to which storage and passage throug h the subsurface can attenuate or even remove such contaminants is a vital area of research. In some cases, the aquifer may even have some deleterious impact on the recovered water, eg . mixing with an existing brackish water, or adding iron and manganese. "RECLAIM WATER" was a Specific Targeted Research Project supported by the European Commission under the Thematic Priority 'Global Change and Ecosystems' of the Sixth Framework Programme. The project started in October 2005 and ran till December 2008. The project consortium c onsists of universities, research and technology institutes, as well as technology providers and water utilities, with a total number of 20 partners from 16 countries (European Union Member States, plus Australia, China, Israel, Mexico, Singapore and South Africa).

Full Scale Studies The majority of the data was generated in a set of globally distributed case studies (Table 1 ). These also served as a basis to validate technical and managerial concepts, and prove their practicability and effectiveness, account for a variety of types of treatment

62 APRIL 2010 water

Injected source

Advanced water treatment

Recharge method

Recharge rate 3

Salt intrusion barrier + drinking water source

UV+ Chlorination

19,000 m3 /d (2006)

Public park irrigation Street cleaning

Soil Aquifer Treatment a) Infiltration ponds b) dug well

Intermediate chlorination against blofoullng In SAT conveyan ce pipe

339,000 m3 /d (full site)

Irrigation (accidental drinking water quality)

Chlorination,

2.5 Mm3/y

Sustainable groundwater management Potable water supply

350·500 m3/d

None (pilot site)

2.7 Mm'/y

Potable water supply

950m3 /d

Intended Irrigation, industrial use and drinking water production

2.16Mm3/d

Industrial use. Domestic use. Potable water production. Irrigation

chlorination

Injection

Sabadell SPA IN

Secondary effluents (activated sludge + nutrient removal)

none

Infiltration through river bed

Shafdan ISRAEL

Secondary effluents (activated sludge + nutrient removal incl. Bio·P)

a) full scale: none

via a sinkhole

b) pilot unit: Ultrafiltration

Torreele/ Wulpen BELGIUM

Tertiary effluents (low loaded pre· denitrificatlon activated sludge system+ simultaneous chemical P· removal)

Ultafiltration + chlorination + reverse osmosis

Dune infiltration

Gaobeldlan CHINA

Secondary effluents (activated sludge + nutrient removal)

coagulation + sand filtration + ozonatlon + slow sand filter

Well Injection

Atlantis SOUTH AFRI CA

Secondary effluent (nitrificationdenltrificatlon steps (anaerobic-anoxlc· aerobic) mixed with Urban stormwater runoffs

none

Infiltration ponds

Salisbury AUSTRALIA

Urban stormwater

Wetlands, (in· stream basins + holding storage basins+ cleanslng wetland)

Aquifer storage transfer and recovery (ASTA)

Tula Valley MEXICO

Raw wastewater mixed with stormwater and natural surface water

none

Irrigation (atypical SAT)

processes, recharge methods and end uses of water, and in degree of economic development. As can be seen in Table 1 , treatment of wastewater before recharge ranged from none (Mexico), to conventional secondary treatment, to advanced treatments such as membrane filtration.

Managed aquifer recharge can be safe and reliable for water recycling.

Reuse purpose

4.4 Mm /y (average)

Secondary effl uents (conventional activated sludge + biological treatment plant)

Nard6 ITALY

Post treatment

3

- 120m /d (pilot site)

aeration, rapid sand filtration + UV disinfection prior to distribution

Ion exchange+ Chlorination

Chlorination (only for drinking water production)

The Australian contribution came from a project to improve the quality of harvested stormwater using a multi-well system, conducted by CSIRO, United Water and City of Salisbury in partnership with SA Water and th e SA and Commonwealth Governments (Rinck-Pfeiffer et al (2005), Dillon et al (2008b)).

Results from case studies Microbial contaminants

Besides the standard indicator parameters for microbiological water

technical features


managed aquifer recharge quality such as total coliforms, E. Coli, Enterococci and Clostridium spores, an enhanced spectrum of parameters was considered including parasites, protozoa, pathogenic bacteria and viruses as well as antibiotic resistance genes. It could be confirmed that advanced treatment schemes, e.g. those utilising membrane filtration, could readily remove pathogens. For other feedwater qualities, sub-surface processes can significantly attenuate them. Risk assessments at four sites showed the value of aquifers in pathogen attenuation (Page et a/ 2010). Bulk organics

Dissolved organic carbon {DOC) was measured at several points in each MAR system as an indicator of water quality im provement. The organic matter was characterised using size exclusion chromatography (SEC), fluorescence (excitation emission measurements, EEM) as well as UV detect ion. The average content of bulk organic carbon (DOC) in the secondary effluents and stormwater ranged from 5 - 15 mg/L and in the final groundwaters from <1 5 mg/L. In all cases, except for recharge of very highly treated water in Belgium, aquifer residence measurably red uces DOC. In the Mexican case study, where raw wastewater mixed with stormwater is used as irrigation water, passage thro ugh the soil and an aquifer leads to a significant DOC decrease from 40 45 mg/L to 15 - 5 mg/ L.

City of Salisbury's stormwater harvesting facility at Parafield airport. Reedbeds are used to improve water quality prior to recharge. They are covered to avoid attracting birds to the airport. (Visiting student from Toulouse Univ, Sarah Kremer, taking samples.) Photo: Karen Barry, CSIRO.

Organic micropollutants

The resu lts for the fate and behaviour of selected refractory pharmaceuticals during d ifferent treatment steps and different SAT retention is of specific interest. As an example, carbamazepine (an antiepileptic drug) was found in all secondary effluents, except from one {where it is obviously not prescri bed), varying from 60 - 1,400 ng/ L. Carbamazepine was found in groundwat ers recharged with treat ed effluent but at much lower concentration

{10 - 600 ng/ L). Due to its high mobility and non-biodegradability carbamazepine is therefore identified as a wastewat er indicator. In general, iodinated contrast media (ICM) contri bute to the highest share of single substances in domestic effluents as well as in recharged groundwater, especially diatrizoate, iohexole and iopamidole which were detected at Âľg/ L range and are also regarded as tracers of sewage. No clear correlation was identified between the conte nt of ICM's and the bulk parameter absorbable organic iodine values (AOI), which varied between 10 and 30 Âľg/ L in abstracted groundwaters. The effluent concentrations of the investigated sulfonamide and macrolide antibiotics (sulfamethoxazole, sulfamethazin, clarithromycin, roxithromycin, erythromycin and trimethopim) varied from 50 1,300 ng/ L, depending on the degree of treatment. In the abstracted groundwat er significantly lower concentrations were detected, depending on the SAT conditions, ranging for single compou nds from O 300 ng/ L. Temperature, retention time and the specific redox conditions in the aquifer are important factors for effective removal of each biodegradable pharmaceutical.

Injection well head at Parafield Gardens aquifer storage transfer and recovery site, with cover folded back. Each well is completed at an interval between 165 and 182m in the T2 Tertiary limestone aquifer. Photo: Karen Barry, CSIRO.

Nine different N-nitrosamines in secondary effluents have been detected where disinfection is applied. Concentrations varied between 0.5 55 ng/ L, with large fluctuations

water APRIL 2010 63


managed aquifer recharge measured at each site. The resu lts suggest the potential for optimisation of disinfecti on practice. In recovered groundwater only two nitrosamines compounds were found at one site at a very low concentration. Other trace organic com pounds have been measured and detected mainly in effluents and first treatment st eps such as bisphenol A, estrone, ibuprofen, diclofenac, naproxen, benzafibrate, benzotriazole and t olyltriazoles.

Table 2. Overview of the treatment trains investigated within RECLAIM WATER for wastewater sites. Main Objective

Effluent type

Treatment steps

APT

-

CAS wetland .

SAT' MBA

wetland CAS

Aquifer material column (fractured aquifer)

.

MBA

Water reclamation technologies Parallel to the investigation of the full scale case studies, the effectiveness of both natural and tech nological water reclamation options which can be applied prior to aquifer recharge has been assessed in extensive pilot and lab scale tests (Table 2). The investigations included constructed wetlands, slow sand filt ers, advanced primary treatment in a developing co untry context as well as advanced options such as membrane bioreactors, dense membrane processes, ozonation and process combinations also for treatment of process-derived waste brines, e.g. utilising biological activated carbon treatment plus membrane fi ltration prior to capacitive deionisation. The results from RECLAIM WATER (cf Table 2) can be summarised as follows: Soil and sub-soil passage

Micropollutant removal by sorption as well as by degradation was observed during soil passage. Degradation of ph armaceuticals does not necessarily correspond to a full-fledged mineralisation, but may be incomplete, leading to one or several transformation products with mostly unknown toxicological characteristics. The degree of removal was shown to depend on : • the compound: soil and aquifer passage feature a general degradation capability which is related to the hydraulic residence time, which is generally much higher than in engineered systems such as activated sludge treatment plants • organic c ontent of the soil with degradation and sorption increasing with higher organic content • the availability of an electron acceptor; degradation being comparable under aerobic and anoxic

64 APRIL 201 0 water

(Sub-) Soil columns (different material types)

Ozone

(Sub-) Soil columns

Perozone

(Sub-) Soll columns

Ozone

(Sub-) Soil columns

Perozone

(Sub-) Soil columns

CAS

Chemical oxidation

MBA UV

-

MBA UV/H2O2

brine treatment with reed bed CAS

MF+RO

brine treatment with ozone brine t reatment with GAC + MF

Brine treatment CAS

MF +RO

brine treatment with BAC + UF + CDI brine treatment with BAC + CDI

NF MBA

brine recycle direct into MBA Ozone+ NF

NF/AC hybrid processes

PAC+ NF CAS

Sand filtration NF +GAC

Decentralized treatment

MBA

Reed bed

partial domestic water reuse infiltration

• Abbreviations: APT = advanced primary treatment, BAC = biological activated carbon, CAS = conventional activated sludge treatment, CDt = capacitive delonisation, GAC =granular activated carbon, MBA =memb<ane bloreactor, MF = microfiltration, NF = nanofiltration, PAC =powdered activated carbon, RO = reverse osmosis, SAT = soil aquifer treatment, UF = ultrafiltration, UV = ultraviolet light

conditions but lower under anaerobic conditions for many, but not all, pollutants • compou nd concentration levels: e.g. degradation of antibiotics is significant after adapt ation to concentrations >0.1 mg/ L • moisture c ontent (e.g. in soil with 2% humidity primidone was removed after sufficient contact time) • mat ching tech nological treatments to aquifer capabi lities for treatment can lead to cost - and energy-efficient attainment of water q uality requirements for reuse (Dillon et al 2008a) Some compounds, e.g. carbamazepine and diatrizoate were persistent in the subsurface and therefore are suitable as wastewater tracer compounds.

Ozonation of effluents

Ozone removes a broad range of compounds. The removal of the parent compounds result s in the format ion of oxidation products of which some are reactive and toxic (e.g. aldehydes). Since the initial, fast ozone depletion in wastewater is accompanied by OHradical formation (cat alyzed by the organic matter present), ozonation in this matrix may be regarded as an advanced oxidation process.

Membrane treatment Porous membranes do not ret ain dissolved compounds but improve the hygienic quality of the effluent and also retain antibiotic resistance genes (Bockelmann et al., 2009). The retention of dense membranes is strongly dependent on t he compo und and the type of membrane. RO membranes retai n most organic compounds to a

technical features


managed aquifer recharge high extent. Known exceptions are NDMA and benzotriazole. The increased removal by the combination of dense membranes with sorption on activated carbon was demonstrated (Kazner et al., 2007).

V

....

--

Transport modelling of pollutants and pathogens Flow and transport models were developed for fou r RECLAIM WATER sites covering various MAR systems in different hydrogeological and hydroclimatic contexts. Taking into account conservative transport of dissolved species (salinity in particular) and pathogens as well as pathogen and contaminant attenuation, which requi res combined/integrated models. Organic cont aminant attenuation was modelled at laboratory and field scale for the Wulpen and Shafdan sites. Inorganic contaminant (manganese) release from the aquifer matrix was investigated for the Shafdan site, taki ng into account the flow in the unsaturated and saturated zone, the kinetics of organic matter breakdown

Inj . Well Rec. Well Fresh Mixture Saline

Diagram derived from groundwater flow and solute transport modelling of the salinity of water in the aquifer at the ASTR site. Four outer injection wells surround two inner recovery wells. The original brackish aquifer was freshened by injecting reedbed treated stormwater initially into the inner wells and subsequently into the outer wells for routine operation. This configuration gives adequate residence time of water in the aquifer for treatment while ensuring recovered water is fresh for intended uses (from Pavelic et a/2004).

induced by bacterial activity in the aquifer and, the resulting redox zoni ng in the aquifer. The injection of reclaimed freshwat er into a saline multilayer aquifer system was modelled for the Adelaide case study, aiming to meet the

constraints on recovery salinities and residence time (Kremer et al 2010). Pathogen transport and attenuation in the fractured/karstified carbonate aquifer of Nardo was simulated, allowing for pathogen deposition on fracture surfaces

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-

--=-~--~~


managed aquifer recharge using a combination of an analytical approach with numerical flow modelling and particle tracking.

~ Balancing ~storage

Wetland

Injection

Recovery

well

well

Conclusions The RECLAIM WATER project has provided an integrated assessment of different water reclamation and managed aquifer recharge methods and technologies covering a broad range of water quality parameters (including pathogens, antibiotic resistance genes and emerging contaminants), different pre-treatment and infiltration options, different end-uses (potable and nonpotable), raw water sources for replen ishment (from untreated wastewater to highly treated tertiary effluent and wetland-treated stormwat er). The results underline that managed aquifer recharge can be safe and reliable for water recycl ing and assist with adaptation to climate change. Technologies and methods can be tailored to the different socio-economic circumstances. In the context of developing countries' de-intensified natural systems, in particular soil aquifer treatment (SAT) , may also potentially provide a useful water quality at very low costs.

Acknowledgments The European Commission is acknowledged for co-funding the RECLAIM WATER Project under Contract No. 018309 in the Global Change and Eco-system sub-priority of the 6th Framework Programme for Research and Technological Development. The Australian component of RECLAIM WATER, 'Aquifer Storage Transfer and Recovery Project- Stormwater to Drinking Water', was supported by the Australian Government Department of Innovation, Industry, Science and Research through its International Science Linkages Programme. The ASTR project was also supported by the South Australian Premiers Science and Research Foundation and the Australian Government National Water Commission through the Water Smart Australia Programme commitment to Water Proofing Northern Adelaide Project. The Australian partner organisations are CS/RO (Water for a Healthy Country Flagship Program), United Water International, City of Salisbury, SA Water and the Department of Water, Land and Biodiversity Conservation. Contributors to original Reuse09 paper: T. Melin (RWTH Aachen University Germany), M. Ern st, A. Hein, M. Jekel (TU

66 APRIL 2010 water

settlement of gross pollutants and fines

• • • •

filtration aerobic degradation phyto remediation volatilisation

.. C Copyright CSIRO Land ,ndWattr

• anaerobic degradation • pathogen attenuation

Diagram of Parafield stormwater harvesting and aquifer storage transfer and recovery that has been shown to produce water that meets drinking water guidelines through passive treatment only, including storage within an initially brackish aquifer (from Rinck-Pfeiffer et al 2005),

Berlin, Germany), A. Joss, M. Krauss, J. Hollender, J. Asmin, C. McArdell (Swiss Federal Institute of Aq uatic Science and Technology), V. Tandoi (Water Research Inst itute (CNR-IRSA) Italy) , K. Le Corre, P. Jeffrey (Cranfield University, United Kingdom), T. Ternes, J. Benner, G. Fink (Federal Institute of Hydrology (BFG) Germany), M. Sa/got (University of Barcelona, Spain), W. Kloppmann (BRGM France), G. Amy, S. Sharma (UNESCO /HE , Delft, The Netherlands) and T. Wintgens (University of Applied Sciences of Northwestern Switzerland). Cocontributors to current paper: R. Swinton (AWA), A.Regel, S. Rinck-Pfeiffer (United Water), and P. Dillon (CS/RO).

The Author C Kazner is with the Department of Chemical Engineering at RWTH Aachen University in Germany. He points out that the original paper list ed 20 co-authors, representing the inputs to RECLAIM WATER from around the globe. Email: ch ristian.kazner@avt.rwth-aachen.de

Selected References (Note, the original paper cites 35 international references) Dillon P., Page D., Vanderzalm J., Pavelic P., Toze S., Bekele E., Prommer H., Higginson S., Regel R., Rinck-Pfeiffer S., Purdie M., Pitman C., Wintgens T. (2008a). A critical evaluation of combined engineered and aquifer treatment systems in water recycling. Water Science and Technology, 57(5), 753-762. Dillon, P ., Page, D., Pavelic, P., Toze, S., Vanderzalm, J., Barry, K., Levet t, K., Regel, R., Rinck-Pfeiffer, S., Pitman, C. , Purdie, M. , Maries, C., Power , N. and Wintgens, T. (2008b). City of Salisbury's progress towards being its own drinking water catchment. Proc. !WA Intl Water Conf, Singap ore, 23-27 Jun 2008. Kazner C., Fink G., Ternes T., Wintgens T., Melin T. (2007). Removal of organic micropollutants

by nanofiltration in combination with adsorption on powdered activated carbon for a rtificial groundwater recharg e with recla imed wastewater, Proceedings of the 5th /WA Micropol & Ecohazard 2007 conference, 17 20 June 2007, DECHEMA e.V., Frankfurt/Main, Germany, 259-265. Kazner C ., Lehnberg K., Kovalova L., Wintgens T. , Melin T. , Hollender J., Dott W. (2008). Removal of endocrine disruptors and cytostatics from effluent by nanofilt ration in combination w ith adsorption on powdered activated carbon. Water Science and Technology, 58(8), 16991706. Kazner C., Fink G., Ternes T. , Wintgens T., Melin T. (2009). Removal of selected pharmaceutica ls by NF/GAC from effluent s as high quality pretreatment for mana ged aquifer recharge, Proceedings of the Xenowac conference, 11 - 13 March 2009, Paphos, Cyprus Kremer, S. , M iotlinski, K ., Barry, K., Dillon, P. and Levett, K. (2010). Revised Flow and Solute Transport Modelling for ASTA Operations, South Australia. Water for a Healthy Country Flagship Report, Jan 2010. Le Corre, K., de Heyder, 8 ., Masciopinto, C., Aharoni, A., Cikurel, H. , Zhao, X., Salgot, M., Ayuso Gabella, M.N., Saperas, N., Cartmell, E., Jefferson, B ., Jeffrey, P . (2008) . Managed aq uifer recharge with reclaimed wastewater: a compari son study of eight operational case study sites. Proceedings of the 12th Annual Water Reuse and Desalination Research Conference 4-6 May 2008, Denver, USA. Page D., Dillon P., Toze S. , Bixio D., Genthe 8. , Jimenez Cisneros B.E., Wintgens T. (2010). Valuing the subsurface pat hogen treatment barrier in water recycling via aquifers for drinking supplies. Water Research, 44, 184152. Pavelic, P. Dillon, P. and Robinson, N. (2004). Groundwater modelling to assist well-field design and operation for the ASTA t rial at Salisbury, South Australia. CS/RO Land and Water Technical Report 27/2004. Sept 2004. http://www.c lw.csiro.au/publicat ions/technical 2004/tr27-04.p df Rinck-Pfeiffer, S., Pitman, C. and Dillon, P. (2005). Stormwater ASR in practice and ASTA (Aquifer Storage Transfer and Recovery) under investigation in Sal isbury, South Australia. p151-159 in Proc. ISMAR5, Berlin, June 2005.

technical features


stormwater harvesting

STORMWATER HARVESTING AS A WATER SOURCE FOR SOUTH-EAST QUEENSLAND C Tanner, S Leinster, D Hamlyn-Harris Abstract

200

Recent droughts in South-East Queensland (SEQ) and other Australian cities have driven investigations into alternative sources of supply to assist with water security. The capture and use of stormwater is one source t hat can be used to replace potable supplies and thereby take pressure off central supplies. At the same time the environmental impact of urban run-off has led to improved stormwater management practices. These two drivers are leading to new practices and design approaches for stormwater management. To facilitate the uptake of stormwater harv esting the Queensland Water Commission (QWC) commissioned a consultancy to investigate Stormwater Infrastructure Options to Achieve Multiple Water Cycle Outcomes. Through assessment of case studies in SEQ, the consultancy provided: • Cost and performance details of stormwater infrastructure for key types of greenfield developments to meet supply, quality and flow outcomes • Analysis of the influence of key variables on cost and performance of infrastructure such as slope, rainfall, development type/intensity, demand , and storage • Identification of development sc enarios where supp ly volumes beyond the water savings target could be achieved.

Introduction The Queensland Water Commission (QWC) has released the SEQ Water Strategy, which sets out the means to ensure a secure water supply over the

Assessment demonstrates that stormwater harvesting is a feasible alternative.

Rainfall Patt erns in Aus mm/month

180 160 140 120 100 80 60 40 20 0 January

February

March

-

Brisbane

April

May

Sydney

June

Adelaide

July

Perth

August

September October November December

Melbourne

Hobart

Figure 1. Rainfall Patterns in Australian cities. next 50 years, supporting our lifestyles and providing for our water use needs as well as those of the environment. The Strategy includes a water supply guarantee which is to be met by a range of water sources, such as dams, seawater desalination and purified recycled water, as well as an ongoing demand management program. The SEQ Water Grid links all treated water sources; a separate pipeline supplies raw water from Wivenhoe Dam to Toowoomba. Following the release of this strategy, and in the light of recent decisions regarding the Traveston Crossing Dam in SEQ, interest in stormwater harvesting as a potential significant decentralised water source has increased. Stormwater harvesting could reduce demand from the major water infrast ructure allowing deferral of t he necessary investment in that infrastructure. One key mechanism to improving the security of water supply is the mandat ing of local supplies to be provided as part of new developments. The Water Savings Target under the Queensland Development Code requires the substitution of town water supplies by

alternative sources supplying 70,000 litres per year per house and 42,000 lit res per year per townhouse in South East Queensland (different volumetric targets apply in other Queensland climate zones). Alternative sources cou ld include rainwater, stormwater, and recycled wastewater. Another important policy init iative was the Draft Implementation Guideline No. 7 Water Sensitive Urban Design Objectives for Urban Stormwater Management (SEQ Regional Plan, 2005-2031) released by the Queensland Government Department of Infrastructu re and Planning (DIP) in December 2008. This guideline provides the requirements for managing the environmental impacts of stormwater runoff from developments. Guideline No. 7 outlines three criteria: • Manage stormwater quality: to protect receiving water by reducing the percentage of sediment, phosphorus, nitrogen and litter in stormwater runoff generated by urban development, compared wit h that in untreated runoff • Improve waterway stability: to reduce exacerbated in-stream erosion downstream of urban areas by

water APRIL 2010 67


stormwater harvesting controlling the magnitude and duration of sediment transporting flows • Manage the frequency of flows: to protect in-stream ecosystems from the effects of more frequent runoff by capturing the initial runoff from impervious areas. In developed catchments, this will ensure that the frequency of hydraulic disturbance will remain similar to what it was before development. The third criterion is the most significant with respect to stormwater harvesting because it creates the opportunity for capture and beneficial reuse of frequent flow events. The Queensland Water Commission commissioned Bligh Tanner (sustainable infrast ructure) and Design Flow (sustainable water systems) to conduct "The Stormwater Infrastructure Options to Achieve Multiple Water Cycle Outcomes" consultancy. It was commissioned to address the lack of basic information on stormwater harvesting relating to infrastructure needs, cost effectiveness, scheme viability and other considerations for stormwater, such as water quality and flow.

Figure 2. Case Study Location. The consultancy considered two case studies in SEQ, however the methodology and outcomes are thought to be applicable across Australia. Rainfall in SEQ follows a subtropical pattern, with a well defined wet season between October and March, followed by a drier

season. It could be expected that regions with a less seasonal rainfall pattern may experience an increased yield from stormwater harvesting schemes, and better reliability of supply (Figure 1).

Methodology Selection of development sites

Table 1. Stormwater Scenarios. Scenario

2

Name

Stormwater Management Measures

Traditional

• • • • • • •

Current

3

WSUD

4

Stormwater Harvesting at Allotment Scale

5

Stormwater Harvesting at Catchment Scale

6

Stormwater Harvesting to an External Demand

Normal Conveyance Flood Flow Rate Mitigation Traditional, PLUS Queensland Development Code: Water Savings Target Stormwater Quality Management Measures Current, PLUS SEQ Draft Implementation Guideline No 71

• WSUD, PLUS • Stormwater Harvesting at an Allotment Scale • Only investigated for Sippy Downs and reuse was for irrigation only • Same as no 4, but catchment scale stormwater harvesting • Sippy Downs included rainwater tanks and reuse was for irrigation only • North Lakes considered 3 sub-scenarios: - No rainwater tanks, dual reticulation to allotments only - No rainwater tanks, dual reticulation to allotments and public open space - Rainwater tanks and public open space irrigation • Catchment scale stormwater harvesting with a connection to an external demand equivalent to collection and reuse of the runoff from rainfall events up to 15mm • Similar to the above the Sippy Downs scenario included rainwater tanks and North Lakes did not.

1 Since completion of this investigation, the Queensland Government has released the State Planning Policy for Healthy Waters and the SEQ Implementation Guideline No 7. These guidelines confirm the requirement for managing the environmental impacts of stormwater runoff from developments.

68 APRIL 2010 water

The consultancy identified and assessed stormwater infrastructure options for new broad scale developments, based on case studies for real sites at North Lakes and Sippy Downs in Queensland (refer to Figure 2). • North Lakes - Large greenfield development site north of Brisbane situated on moderate topography (rolling hills). Most of the development has been designed and constructed. Within the development site the following development parcels were selected for case study assessment: - 20ha low density residential, 11-12 dwellings per ha - 100ha low density residential, 11-12 dwellings per ha - 500ha low density residential , 11-12 dwellings per ha - 20ha industrial • Sippy Downs - Medium density development proposed for the Sunshine Coast. The layout and infrastructure associated with the development has been designed and implementation is progressing at the time of this assessment. The following case study options were assessed:

technical features


stormwater harvesting - 40ha residential, 100 dwellings per ha

Yield kl/ha/day

- 40ha residential, 40 dwellings per ha.

16.0

T hese developments were selected for case study assessment for the fo llowing reasons:

14 .0

• they provide a representative mix of land use, scale, density and topography

10.0

• they provide a mix of alternative stormwater infrastructure • the developments are considered to be r epresentat ive of the bulk of development that will occur in SEQ

12.0

8.0

6.0 4.0 2.0 0.0

+

W SU D/CURRENT

---, SWH TO SITE

• they address greenfield and infill development

Figure 3. Stormwater Harvesting Yield (Average).

Stormwater infrastructure scenarios

Storage

Each of the case studies was investigated across a range of stormwater scenarios. The scenarios represent the range of possible approaches t o stormwater fro m the trad itional focus on flow conveyance and flood mitigation to the contemporary best practice incorporating water sensitive urban design (WSUD) and stormwat er harvesting. General descriptions of these are provided in Table 1.

Storage is required to buffer the episodic nature of stormwater runoff and ensure end use demands are met. The size of storage is dependent on reuse demand and the desired wat er supply reliabi lity. In the past, the storage size required to attain a high reliability has been viewed as a major constraint to the widespread application of stormwater harvesting. However, in the urban context, stormwater harvesting may be adopted

The Stormwat er Harvesting Guidelines will assist you in the planning, design and implementatlon of stormwat er harvesting schemes - focu sing on developing localised stormwater harvesti ng in urban areas, harvest ing st ormwater from local cat chments an d reu sing it within t he local comm unity.

SWH TO EXT

to supply non-potable end uses using modest storage sizes to achieve moderate water supply reliability, with mains supply as a back-up if necessary. A large constant demand delivers the most cost efficient stormwater harvesting scheme with the highest yield. This is because the higher the demand for stormwater, the more rapidly the storage is drained, thereby creating space to capture the next rainfall event. The volume of the storage for each case

Download here! www.waterbydesign.com.au/guidelines This guideline is complement ed by a one day t raining course.


stormwater harvesting study and scenario was est ablished based on the economic limit of

Levelised Marginal Cost $/ML (Capex. O&M)

performance of t he storage (i.e. the diminishin g rate of return on the storage versus demand met curve).

S25,000 $20,000

Treatment for reuse The existing draft Australian Guidelines for Water Recycling: Stormwater Harvesting and Reuse (Phase 2) (EPHC ,

$15,000 $10,000

NHMRC, & NRMMC 2008b) do not define specific water q uality classes for stormwater uses. Instead, the gu idelines

so

provide Log Reduction targets for various uses for virus, parasite and bacteria concentrations. To assist in defining treated water quality requ irements, the follo wing quality levels have been defined (Draft Stormwater Harvesting Guidelines, Healthy Waterways Partnersh ip 2009): 1. Primary Contact (PC) - for uses such

...

$5,000

r-WSUD/CURRENT

SWH TOSITE

SWHTO EXT

Figure 4. Levelised Marginal Cost of Stormwater. Table 2. Marginal Cost. Capital and Ongoing Cost (incl Land) $NPV/dw Sippy Downs Sippy Downs North Lakes North Lakes North Lakes 100 dw/Ha 40 dw/Ha 20Ha Res 100Ha Res 500 Ha Res

Scenario Description

as community swimming pools 2. Non-Potable High Contact (NP HC) -

I

Traditional 2

Current

$500

$800

$4,400

$4,500

$3,500

$500

$800

$4,400

$4,500

$3,500

$8,800

$6,300

$5,900

for uses w here t here is a high probability that people w ill come into contact w ith the water during u se , e.g. toilet fl ush ing,

3

WSUD

4

$1,200

$2,400

private garden watering , high use public facilities

WSUD + SWH (Allotment Scale)

5a**

$1,200

$2,300

3. Non-Potable Medium Contact (NPMC) - for uses where there is a moderate probability of contact d uring use, e.g. low

WSUD + SWH (Catchment Scale, Dual Retie to Lots)

5b**

WSUD + SWH (Catchment Scale, POS irrigation, Dual Retie to Lots)

$9,100

$6,800

$6,100

4. Non-Potab le Low Contact (NPLC) - for

5c*

WSUD + SWH (Catchment Scale,

$8,600

$6,500

$5,100

use s w here there is a low probability of contact, e.g. industrial uses or where public access is effectively restricted

6**

WSUD + SWH to External $1 ,300

$9,600

$5,200

$2,600

use public facilities or dust suppression

POS irrigation only} $2,700

during irrigation.

*RWT all cases, •• Sippy Downs RWT were allowed, at North Lakes RWT were not allowed In general, with appropriate levels of treatment, harvested stormwater is co nsidered to be suitab le for all uses which could be supplied by treated recycled water, including toilet flushing, garden/landscape wateri ng, general maintenance and car wash ing.

Levelised Gross Cost $/ML (Capex, O&M) S50,000 $45,000 S40,000 S35,000

Results Select results are presented in the following charts. The charts have been formulated as fo llows:

• "WSUD/Current" represents Scenarios 2 and 3

• "SWH to Site" represents Scenarios 4

$30,000 S25,000

+ - - - --I--- - - - - - - - - - - - - - - - - - -

t -+-- - - - - - -,--- - - - - - - - - - -

S20,000 S15,000 Sl0,000 S5,000

+--------------------,

so

------,-

WSU 0/CU RRENT

SWHTOSITE

and 5

• "SWH to Ext" represents a yield

----,

r SWHTO EXT

Figure 5. Levelised Gross Cost Stormwater Infrastructure.

generated by co llecting and reusin g the whole of the frequent flow objective to capture and reuse the runoff from impervious areas and all rai nfall events up to 15m m • Bars represent the highest and lowest values estimated

70 APRIL 2010 water

• Dots represent the median of the values estimated

1. The progression from WSUD/Current to SWH to Ext shows a steady rise in the median yield

Yield estimates from the various scenarios are shown in Figure 3. The following observations can be made:

2. The med ian yield is 3.6 kUha/day for SWH to Site, an d 9 kUha/day for SWH to Ext.

technical features


Costs were determined on a stand-alone basis for al l the stormwater and rainwater harvesting opt ions (marginal costs), as well as including all stormwater costs (gross costs). The standalone basis is presented first, as this represents the marginal costs of stormwater and rainw ater harvesting.

BECAUSE WATER IS CRITICAL TO THE LIFE OF YOUR PLANT

Figure 4 shows t he levelised marginal cost per megalitre of water supplied. Table 2 provides t he same costs per dwelling served. The following observations can be made: 1. T he levelised marginal cost of stormwater (based on capex + O&M) for WSUD/ Current is $5,595/ ML, for SWH to Site is $5,631 / ML, and for SWH to Ext is $2,535/ ML 2. Costs of any of the stormwater harvesting options on a per dwelling basis are significantly lower for the medium density cases, i.e. at Sippy Downs, than for the low density development at North Lakes. 3. Medium density cases on ly represent a relatively small cost increase over and above the Current/WSUD options. To provide context for the above, the total costs of all st ormwater conveyance, peak flow mitigation, water quality management, rainwater and stormwater harvesting have also been estimated (Figure 5). These results suggest the followi ng: 1. The WSUD/Current scenario shows a wide spread of costs, due to the low demands and yields for t he industrial estate case study 2. The median value of the cost decreases consistently for the three groupings from $23,000 per ML, to $15,000 per ML, to $5,000 per ML.

Discussion The yields from the schemes investigated provide a range for stormwater harvesting to site uses of 4 to 5 kUha/day. Where there is a large external demand the yield is about double this, i.e. 8 to 10 kUha/day. This indicates that if stormwater harvesting was adopted on a significant scale in SEQ, it may have the potential to reduce the demand on current or other planned infrastructure. The assessment has found that stormwater storages vary in size depending on the reuse situation but remain relatively small to achieve a yield of approximately 70-75% of total demand. For stormwater harvesting within a site (i.e. capture stormwater from a catchment t o supply demand within the same catchment) the storage size is around 60-80 kUha and to an external demand is around 90 kUha. The investigation has confi rmed that stormwater harvesting can play a role in protecting downstream aquatic ecosystems. The introduction of impervious surfaces can lead to significant changes to hydrology and increased pollution, which in turn can result in irreversible impacts on sensitive aquatic ecosystems. Stormwater design objectives have been established to manage t he impact of t hese changes as outli ned in the Implementation Guideline No 7 Water Sensitive Urban Design (SEQ Regional Plan 2009-2031 ). The water balance assessments confirmed that t he pre-development hydrology is preserved for Scenario 6 where t he first 15mm of flow from impervious surfaces is captured and reused (i.e. strict compliance with frequent flow objective). The other stormwater harvesting scenarios (Scenarios 4 and 5) go some way towards re- establishing the pre-development hydrology, however , the smaller demand associated with reusing water within the catchment means reuse of the fu ll 15mm of stormwater from impervious surface is not achieved.

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stormwater harvesting A number of factors can have a significant influence on the costs of a stormwater harvesting scheme. The obvious ones are things like conveyance costs , storage costs, environmental mitigation costs, treatment and distribution costs. This study has found that the opportunity cost associated with the use of land for stormwater harvesting uses, and in turn whether or not stormwater harvesting infrastructure is above or below ground has a significant influence on cost. Additionally, at a small scale, treatment (filtration and disinfection) requ irements tend to dictate cost whereas at a large scale the distribution network dictates costs. To satisfy the provisions of the Queensland Development Code most developments implement rainwater tanks. To reflect this practice all scenarios except the Traditional, North Lakes Scenarios 5a and 5b and Scenario 6 included rainwater tanks. The North Lakes scenarios 5a and 5b do not include rainwater tanks because it was considered that if stormwater harvesting was to provide source substitution in accordance with the Queensland

Development Code, and a dual reticulation system back to allotments was provided then rainwater tanks wou ld essentially be doubling up on infrastructure at a significant cost. The results suggest that the levelised cost of harvested stormwater is around $1,000 to $5,000 per ML, which is at the lower end of the range of costs presented for rainwater tanks. Stormwater harvesting appears to be c omparable in costs to other options such as Purified Recycled Water and Dual Reticulation Recycled Wat er, slightly higher in cost than the water from the Gold Coast Desalination Facility, and significantly higher in cost than those anticipated for water from the Traveston Crossing Dam. All of these options have different drivers, advantages and disadvantages, and it is not the purpose of this study to make indepth comparisons between the options. The key difference is that stormwater and rainwater do not provide the same level of reliability.

Conclusions The findings of the study provide insight into when st ormwater harvesting is a

viable water supply option, and the key factors affecting this viability.

Supply/Yield • Yield is maximised when there is a large demand (or large storage such as aquifers) which allows for storages to be drawn down and readily fill at the next rainfall event • This reduces the levelised cost of the water, and reduces the environmental impact of stormwater flows • To achieve this in pract ice it wi ll be necessary to have high density development, or a large external water user • A supply reliability of 70-75% has been designed for: improved reliability can be achieved through larger storage size but this leads to a worsening cost to supply ratio • The yields from the schemes investigated provide a range for st ormwater harvesting to site uses of 4 to 5 kUha/day • Where there is a large ext ernal demand the yield is about double this, i.e. 8 to 10 kUha/day.

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11eeca Cost • The 'add on' costs for stormwater harvesting are not large compared to overal l infrastructure costs • Stormwater harvesting has the potential for greater water supply yields at lower costs than rainwater tanks, particularly for large developments, or where high water demands can be supplied • A key cost issue is the cost of land for stormwater infrastructure (and in particular storage), where infrastructure leads to reduced lot yield the cost increases significantly • Storage in an existing drainage reserve or a suitable aquifer for storage greatly reduces the cost of stormwater harvesting • Draining catchments to a si ngle location (or smaller number of discharge points) results in lower costs of storage, treatment and distribution of stormwater. This can readily occur in moderate to steep catchments (2 - 10% slopes) rather than flat sites where catchments are typically split to avoid large pipe drainage infrastructure • La rger scale development appears to reduce the costs on a levelised and per ha basis. The minimum scale t hat should be considered is around 20 ha, but 100 ha or more is desirable • Low density development provides a lower levelised cost per ML for water, but higher density development provides a lower cost per dwelling for water.

Environmental • A stormwater harvest ing scheme with a high yield has the potential to significantly contribute to improvement in downstream aquatic ecology.

Factors for successful stormwater harvesting The following factors were identified as contributing to a successful stormwater harvesting scheme: • Large scale development • High demands (from high density) • Moderate slopes which drain to single/few points • Cheap storage. It is stressed that this study has fou nd a significant spread in the results, albeit with some clear trends. This indicates that there is w ide variability in the way a stormwater harvesting sc heme should be conceived and implemented, so every harv esting system should be considered on its merits and optimised to suit t he situation in hand.

General • Stormwater infrastructure can achieve a number of outcomes (e.g. water quality, supply and environmental flow) and therefore cost efficiencies do occur • In a number of development scenarios stormwater harvesting can deliver water supply to meet and exceed t he water savings target at a cost comparable to rainwater tan ks, and in some cases cheaper • Stormwater harvesti ng should be the means of meeting the Water Savings Target under the Queensland Development Code for certain developments • There are likely to be many areas identified for development in the SEQ Regional Plan 2009-2031 that w ill be suitable for c ost effective implementation of stormwater harvesting

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stormwater harvesting • If wide uptake of stormwater harvesting to exceed the water savings target occurs further reductions in demand on central supplies may be achieved, further delaying the need to build new infrastructure. Future work

A range of other factors requires consideration in the implementation of stormwater harvesting systems. These are not the subject of this study, but nevertheless, a list of these issues has been compiled to provide some context to this work. Issues for further consideration are as follows: • Developing the information from this consultancy and other documents (such as the Healthy Waterways Partnership Draft Stormwater Harvesting Guidelines) into information products and workshops for local government and developers • The findings of this study could be applied to future development areas identified under the SEQ Regional Plan to map areas where viable stormwater supplies can be harvested • Further analysis will allow for an estimation of stormwater supply volumes • How the costs of stormwater harvesting are assigned is a key question - for example charging on a volumetric basis would lessen the cost burden on house price (currently the costs of rainwater tanks are incorporated into the house price)

• Ensure that local and State government legislative approvals are sufficient to ensure schemes are effective but are not overly burdensome • Clarify the impact of land costs on stormwater harvesting systems • Review the impact of rainwater tanks on t he effectiveness of stormwater harvesting systems • Identify the advantages and disadvantages of a stormwater harvesting scheme, including community benefits, environmental benefits, water security etc.

Recommendations This study provides a strong basis over a range of scenarios and development types for the co nsideration of stormwater harvesting as a source of water for SEQ. The modelling and analyses herein have been undertaken with rigour, providing a set of results that can be used with confidence. The results demonstrate that stormwater harvesting is a feasible alternative to a range of other alternative water sources. It is recommended that the results of t his study be used to underpin a study into the broader application of stormwater harvesting in SEQ.

The Authors

• Who owns and manages a scheme needs to be addressed to ensure efficient and effective operation and to inform pricing frameworks • Incentives for stormwater harvesting could be considered

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Wed 27, Thurs 28, Friday 29 October 2010 Civic Theatre, Wagga Wagga The strength of Pipes Wagga is to provide • presentation of quality papers • live field demonstrations • experienced on site trade personnel • "real life matters" shared & resolved Pipes Wagga challenges the roles of pipe assets to gain integrated solutions and efficiencies to help resolve the major water industry issues. Pipes Wagga is hosted by Wagga Wagga City Council and Riverina Water County Council and supported by AWA, Water Directorate & Engineers Australia

All enquiries: Conference Coordinator Penny Lamont 02 6924 6311 0427 433 795 penny@pipeswagga.com.au www.pipeswagga.com.au 7 4 APRIL 2010 water

Chris Tanner and David Hamlyn-Harris are Directors of Bligh Tan ner Consulting Engineers in Brisbane, with a focus on sustainable urban development and minimisation of the ecological footprint of development. Chris has a broad grasp of land development issues, and integration of civil engineering solutions with the environment. David has a particular interest in integrated water management, including rainwater tanks, stormwater harvesting and water recycling. Email: chris.tanner@blightanner.com.au Shaun Leinster is an Environmental Engineer with DesignFlow, a team of stormwater professionals who draw heavily from natural systems in their approach to collecting, fi ltering, reusing, conserving and enjoying water in urban spaces. Email: shaun@designflow. net.au

References Natural Resource Management and Ministerial Council {NRM MC), Environmental Protection and Heritage Council {EPHC) and National Health and Medical Research Council {NHMRC) 2008, The Guidelines for Augmentation of Drinking Water Supplies Natural Resource Management and Ministerial Council {NRMMC), Environmental Protection and Heritage Council {EPHC) and National Health and Medical Research Council {NHMRC) 2009, The Guidelines for Stormwater Harvesting and Reuse Healthy Waterways Partnership, Draft Stormwater Harvesting Guidelines 2009 Department of Infrastructure and Planning, Queensland Development Code Department of Infrastructure and Planning {DIP) 2008, South East Queensland regional plan 2005-2026 Implementation guideline No. 7 DRAFT: Water sensitive urban design - design objectives for urban stormwater management. Department of Infrastructure and Planning {DIP) 2009, South East Queensland regional plan 2009-2031 Implementation guideline No. 7: Water sensitive urban design - design objectives for urban stormwater management. Department of Environment and Resource Management {DERM) 2009, Draft State Planning Policy for Healthy Waters.

technical features


stormwater harvesting

[-;;] refereed paper

URBAN STORMWATER SUPPLIES DRINKING WATER AT ORANGE, NSW C Devitt Abstract Orange City Council in central NSW has been the first Council in Australia to implement intentional urban stormwater harvesting for drinking water supplies. Furthermore it has done this making use of engineered treatment processes and an existing water supply dam. Council received the necessary authorisation from OWE in July 2008 to commence construction under an emergency approval. Construction work began in September 2008 and is about to commence operation in continuous mode. This project has evolved from concept to operational reality within 18 months at a cost of $5 million involving extensive consultation with the comm unity and government authorities. Resu lts of the first stage of commissioning are summarised in this paper.

Introduction The city of Orange is located approximately 250km west of Sydney in the Central Tablelands of New South Wales. Challenges in operating a water supply system for the population of 38,000 are attributed to the city's location high in the catchment, the lack of any substantial river system and limited groundwater supplies. The city therefore relies on a network of creeks wh ich traverse the rural areas to fill local water storages. Continued dry conditions over the past few years and subsequent well below average runoff saw the city's water supply levels gradually drop. Level 5 water restrictions were imposed in May 2008 and in August 2008 Council's two supply storages dropped to less than 25% capacity. Without significant storage inflows, the city had approximately one This paper was prepared by the Editor based on the original presentation at REUSE 09, together with updates and data supplied by the listed author. At Ozwater'10 the project was announced as Highly Commended in the AWA Infrastructure Project Innovation Award.

LEGEND

r:J lAFAAMlNG â&#x20AC;˘

. -

1C RURAL RESIOEHTIAL

7 UMRONMENT PROTECllOH WATER CAOASTRE IN.ACKMAN$ SWNAP CREEK CATCHMENT

-Figure 1. Blackmans Swamp Creek Catchment. year of water supply remaining. With the real potential of restricted water access the future growth and development of Orange was facing challenges. In response, Orange City Council began pursuing an integrated package of both non-structural and structural programs to help secure the city's water needs. Non-structural measures aimed at reducing the water demand included the introduction of water restrictions, a leak detection and pressure reduction program, a rainwater tank subsidy, an exchange program for showerheads, the installation of water saving devices in all Council buildings, liaison with large water users to reduce consumption and extensive commun ity education including t he 'Watertight' program supported by local media where 1O households competed to achieve the lowest water usage per capita. As a consequence of these initiatives water usage in Orange dropped from a high of 7,100ML in 2002 to 4,100ML in 2009, during which time the city experienced sustained growth. Structural initiatives considered included reconnecting historical water supplies, groundwater investigations,

extraction from disused mines, connection with adjacent local water utilities, stormwater harvesting from upstream and downstream catchments and regional water security initiatives. Stormwater harvesting emerged as the most viable option worthy of detailed investigation. The first stage of such harvesting has concentrated on Blackmans Swamp Creek, which drains the highly developed southern and eastern part of the city, including a mix of rural , residential, industrial and commercial areas, representing 70% of the city's urban footprint (Figure 1).

Blackmans Swamp Creek Harvesting Project The Blackmans Swamp Creek Stormwat er Harvesting Scheme captures and transfers a portion of the urban storm flow from Blackmans Swamp Creek into the city's main water storage, Suma Park Dam, where it supplements the city's raw water supply. The scheme

The first scheme to harvest an urban catchment. water APRIL 2010 75


~ refereed paper

stormwater harvesting is capable of providing 800M L to 1,200ML of additional water into Orange's raw water supply each year; this is up to 30% of the city's current average annual emergency water demand. Key infrastructure elements of the scheme will allow future harvesting schemes on other urban creek catchments to add additional water to the system, potentially up to 40%, further securing the sustainability of Orange's water supply. A number of key elements make this system viable.

Infrastructure These include the close proximity of Blackman 's Swamp Creek to Suma Park Dam, the availability of key existing infrastructure and the very high level of treatment provided by Council's main water filtration plant at lcely Road , which treats the raw water from Suma Park Dam. This includes ozone treatment to destroy pathogens and Biologically Activated Carbon Filtration to consume the remnants of the compounds destroyed by the ozone. The regularity of flows in Blackman's Swamp Creek was also a key element. Because of the large impervious areas in the urban catchment reliable runoff occurs after every rainfall event.

The offtake weir.

Environmental Factors

(Orange City Council) without consent on any land. Whilst development consent was not required to construct or operate the scheme, Council had an obligation under Part 5 of the NSW Environmental Planning and Assessment Act, 1979 to consider the environmental impacts of the activity. A Review of Environmental Factors (REF) (Geolyse, 2008) was prepared to assist in the determination process.

The scheme was defined as a stormwater management system under NSW State Environmental Planning Policy (Infrastructure) 2007 that could be carried out by or on behalf of a public authority

The REF provides a comprehensive outline of the project and concluded that the construction and operation of the scheme is unlikely to result in a significant adverse environmental impact.

Odour Control New Generation Photoionisation - Technology

NEUTRAL OX

• Waste Water Treatment Plants • Pump Stations

An integrated daily water balance model was developed to assess the stormwater harvesting scheme and other water augmentation schemes being considered.

• Thickener and Storage • Working at the Odour Source • Low Maintenance • No Water, no Chemicals • Low Power Consumption

76 APRIL 2010 water

This resulted in a series of operating rules involving establishing flow trigger points when harvesting can commence, maintaining base flows , clearly det ermining t hat the project wil l not cause undue impact to the downstream environment. On the contrary the work actually improves the existing situation through the removal of suspended solids via a series of Gross Pollutant Traps (GPTs), as well as reducing peak flow levels thus reducing the likelihood of erosion and damage during high flow events. Ongoing stakeholder engagement continues as the scheme operates.

Water Quantity

• Sludge Treatment Processes

Please contact: Industrial Plant & Service Australia Pty Ltd 99a South Creek Road, Dee Why NSW 2099 Tel: 02 9981 2000 Email: eroth@ipsaus.com.au

It is acknowledged that taking water out of the system must have a downstream impact. The challenge was to adaptively manage the scheme's use so that this impact is not significant and that the needs of downstream users and the aquatic environment are not compromised (Geolyse, 2008).

Pump Station Odour Control

The model used 120 years of daily rainfall data (1888 to 2007). Catchment runoff calculations were used to generate a daily stream flow series which was used as inflow to t he various storages in the system.

technical features


~ refereed paper

stormwater harvesting Water Quality Water quality is a critical factor in the success of the harvesting scheme. Urban stormwater can include a range of pollutants that left untreated or unmanaged, could pose a threat to the city's raw water supplies. Water quality risk management has been formalised through the implementation of the Framework for the Management of Drinking Water Quality (NHMRC & NRMMC, 2004).

The first release of harvested stormwater flows into Suma Park Dam on 21 April 2009. Model results indicated that the average catchment runoff passing the stormwater harvesting location was approximately 11,870MUyear and ranges from 3,000 to 25,000MUyear. The average monthly flows show wi nter dominance.

Modelling indicated that, on average, 10mm of rainfall across the Blackmans Swamp Creek catchment can produce about 140ML of runoff, but this can range from 90ML to 220ML depending on antecedent conditions and rainfall patterns.

Pipe Lining & Coating PTYLimited

The harvesting scheme has been designed with an integrated suite of catchment, system and operational barriers to manage water quality and the risk associated with using stormwater to supplement the water supply. These barriers include: â&#x20AC;˘ Catchment level - implementation of plans and policies to protect stormwater quality including a Stormwater Management Plan, a Sewer Asset Management Plan and a Trade Waste Policy. The scheme provides an opportunity for community education regardi ng stormwater and


~ r e f ereed pape r

stormwater harvesting catchment management. The primary Gross Pollutant Trap (GPT) was installed in a prominent location where residents can observe functioning and downstream benefits. Interpretative signage was installed at key locations throughout the scheme. • System level - a treatment train approach incorporating a series of system components designed to remove pollutants in the stormwater.

Table 1. Main Harvested stormwater quality targets. Total suspended solids Salinity pH Biochemical oxygen demand Total Phosphorus Total Nitrogen

EColi

• Operational level - operation of the system in a manner that optimises the quality of the stormwater.

Iron

• Finally, the advanced treatment system provided at the lcely Rd WTP, involving ozone and BAC.

Oil and grease

Community Consultation Community resistance to the concept of drinking stormwater was initially thought to be a significant challenge. However, through community education on the treatment processes and the necessity for securing the future of Orange's water supply, community acceptance was achieved relatively quickly and easily. Local and national media coverage, community information session, on-line surveys and explanatory signage at key locations were important factors in ensuring the concept of adding stormwater to the potable supply was widely accepted by residents. The predominant response was not one of concern about water quality but one of urging Council to get on with the work as soon as possible.

Scheme Layout, Operation and Monitoring Major components of the harvesting scheme include: • Two large Gross Pollutant Traps (GPTs); • A harvesting weir (3ML) and Pump Station 1 with a capacity of 450Us; • A 200ML holding pond that is used to balance harvested stormwater flows with the treatment system; • Pump Station 2 with a capacity of 150Us to transfer water from the holding pond through the treatment system to the batch ponds; • A treatment shed; • Two 1 ?ML batch ponds; and • Pump Station 3 with a capacity of 150Us to transfer treated stormwater to Suma Park Dam. The treated stormwater is transferred through an

78 APRIL 2010 water

< 50 mg/L < 20 NTU < 300 µS/cm 6 to 9 < 30 mg/L < 0.5 mgP/L < 5.0 mgN/L

Turbidity

< 10,000 CFU/lOOmL < 2.0 mg/L

Lead Manganese Total Petroleum Hydrocarbons

< 1.0 mg/L < 1.0 mg/L < 10 mg/L < 1 mg/L

existing main towards Suma Park Dam with an extension allowing discharge to the dam . Flows in Blackmans Swamp Creek respond quickly to rainfall and when runoff from the city causes the flow to reach 1OOOUs, Pump Station 1 activates and draws water from the harvesting weir at a rate of 450Us. The operating rules require that a base flow immediately downstream in the creek must be maintained. Harvested stormwater is transferred to the 200M L holding pond where some settling takes place. Water is extracted from the holding pond by Pump Station 2 at a rate of 150Us, through the treatment shed. A flocculant (aluminium chlorohydrate) is added before being pumped into one of two 1?ML batch ponds. In Stage 1 of the project (Batch Mode) samples were taken from two depths in each batch pond for quality analysis. If sample quality met the target values (Table 1), water was then transferred to Suma Park Dam. The combined water is then treated at Councils advanced water treatment facility (ozone and biolog ically activated carbon filters) before being pumped into the city's potable supply system.

Results Water Quantity The first transfer of 12 ML to Suma Park Dam was achieved on 21 April 2009. As at March 2010, 32 harvesting events have been undertaken in Batch Mode, yield ing 525 ML of water, some 15% of the total flow of the creek.and more than 13 % of the city's current demand. Co nti nuous Mode commissioning has now commenced.

Water Quality In batch mode of operation, water was only t ransferred to Suma Park Dam once the water quality analysis passed all the target criteria that had been developed in consultation with Geolyse. Over 130 targets have been set for the water quality of t he batch ponds, the main ones being summarised in Table 1. Sources utilised in setting the targets included the Australian Drinking Water Guidelines (NHMRC & NRMMC, 2004), t he Australian and New Zealand Guidelines for Fresh and Marine Water Quality (ANZECC & ARMCANZ, 2000), Australian Guidelines for Water Recycling (EPHC et al, 2008) and Australian Runoff Quality: a Guide to Water Sensitive Urban Design (Engineers Australia, 2006). Due to various test methods employed by laboratories, over 230 analytes are being reported. It is envisaged that at the end of the commissioning phase and full review of water quality results that some analytes will be removed from the standard analysis sweep (i. e. those that have not been detected) and only tested for periodically.

Quality summary as at 20 January 2010 Pesticides and herbicides • From all samples from Blackmans Swamp Creek (BSC) and the batch ponds there has been no detection of: - Organochlorine pesticides (OCPs) - Organophosphorus pesticides (OPPs)

Following successful operation for ten months, the system will move into Continuous Mode. This involves a continuous cycle of pumping harvested stormwater from the holding pond to Suma Park Dam via the batch ponds, with a turbidity probe providing a continuous indicator of water quality backed up by water samples being taken on average from every 8 ML of water.

• In Batch Po nds t here has also been no detection of: - Glyphosate • Phenoxyacetic acid herbicides: concentrations with in the batch ponds d id not exceed the set target criteria.

PCBs, hydrocarbons, Phenols, voes • From all samples from BSC and the batch ponds there has been no detection of:

technical features


L~ refereed

stormwater harvesting

paper

- Polychlorinated biphenyls (PCBs) - Phenolic compounds - Volatile organic compounds (VOCs); Trihalomethanes, Halogenated aromatic compounds, Halogenated aliphatic compounds, Sulfonated compounds , Oxygenated compounds, Monocyclic aromatic compounds - Asbestos • TPH: was detected within the first sample only from the batch ponds. This did not exceed the target criteria (< 1 mg/L). Physical and chemical

• Turbidity: A strong correlation was found between turbidity and aluminium (r = 0.85), and turbid ity and iron (r = 0.91 ). Turbidity probes have been installed at the surface monitoring point for continuous mode with a target value of < 2 NTU. • Cadmium: One batch pond was resampled due to a cadmium excedence in October. The second sample met criteria for subsequent transfer to Suma Park Dam.

& Grease excedences were within the absolute limits and more than 95% of samples have achieved the target criteria. Water was transferred to Suma Park Dam. Nutrients

• Phosphorus: has not exceeded target criteria for the batch ponds. • Nitrogen: More than 95% of samples from water transferred to Suma Park Dam have been within set target criteria. An excedence occurred with the first batch pond for total nitrogen of 2.7 mg/L, although this was within the target criteria which were set at the time (Version 3, target < 5 mg/L) . Bacteriological

• E. coli, Somatic coliphages, and Clostridium perfringens: No samples from the batch ponds have exceeded set target criteria. The average of E. coli concentrations in the batch ponds has been reduced to 0.2% of the BSC concentrations, S. coliphages to 4.5%, and C. perfringens to 0.3%.

Water, NSW department of Health, and DECCW (EPA), the scheme has moved into "Full Production" . This stage requires different monitoring regimes as confidence is increased in the system. The extension of harvesting to other urban creeks is under consideration with the potential to provide some 50% of current demand.

Acknowledgment The successful development and implementation of th is project has resulted from a very effective collaboration between staff at Orange City Council and Geolyse, Consulting Engineers of Orange, led by Martin Haege. In addition the involvement and assistance from the NSW Office of Water has played a key role in the delivery of the project.

The Author

Conclusions and the Future

• Total Manganese: Four samples Chris Devitt, BE Civil, is Director The first ten months of commissioning reported above the target criteria at an Technical Services, Orange City Council. have demonstrated that urban run-off average of 0.253 mg/L. The 95%ile for Email cdevitt@orange.nsw.gov.au can be harvested and treated to be a manganese in the Batch ponds and Refe rences safe addition to potable supply. Suma Park Dam both exceed the Geolyse Ply Ltd (2008). Blackmans Swamp Creek target criteria. Investigations have After the commissioning period, with Stormwater Harvesting Review of found Suma Park Dam to have joint consideration from NSW Office of Environmental Factors. Orange City Council. naturally occurring manganese which increases in concentration during summer. Subsequent sampling now includes soluble manganese analysis as water quality objectives for the Water Filtration Plant have a target of Reliable Quality and Service from a Company with more than < 0.02 mg/L of l 00 years of expertise in the manufacture of Coa l and Carbon soluble manganese Products for Au stralian Industry of the raw water.

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• BOD and Oil & Grease: Ponds sampled on the 21 / 12/09 reported excedencesforone sample for BOD at 1 4 mg/ L (target < 10 mg/ L), and one sample for Oil and Grease at 5 mg/L (target < 2 mg/L). These BOD and Oil

C&S BRAND GRANULAR & POWDERED ACTIVATED CARBONS JAMES CUMMING & SONS PTY LTD 319 Parramatta Rd, AUBURN NSW 2144 Phone: (02) 9748 2309 (02) 9648 4887 Fax: Email: jamescumming@jamescumming.com.au Website: www.jamescumming.com.au

I

Quality 1S0 9001

............

llc No, 1&28

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water APRIL 2010 79


~ refe r ee d p aper

pumps & pipelines

PUMP AND HEATING EFFICIENCY SOLUTIONS FOR HIGH RISE BUILDINGS R Butler, A Sneddon, M Schwecke Abst ract The use of water flow monitoring data to assist in leakage reduction and to apportion water usage in complex sites has been well documented. However, this flow monitoring data can also be used to improve the energy efficiency of water distribution systems in high rise apartments, hotels and commercial buildings. Sydney Water's Every Drop Counts Business Program is running a pilot program assessing high rise residential buildings, to identify water efficiency improvements. Sydney Water engaged BMT to conduct this pilot. Sixteen high rise buildings have been assessed with more than 600kUday water savin gs identified to date.

Introduction Water flow monitoring can quickly identify issues with existing sites by showing real time usage and quantifying usage rates accurately. This data is then used to generate a water balance from where the first cut of areas to investigate potential water efficiency improvements can be made. For example, in comparison to billing data, which arrives monthly or quarterly, real time monitoring wi ll show exactly where and when a leak or excess use is occurring immediately. This can save large volumes of water and money for little expense. It also allows for accurate sizing of elements of the hydraulic system, especially important when proposing water recycling systems and justifying the capital expense against the water savings. In addition to water savings, the optimisation of hydraulic systems can be improved in relation to energy efficiency, space use efficiency and heat transfer. These are the added benefits to water use efficiency, and are only now beginning to be realised. Flowrate data can be used to assist in resizi ng and reconfig uring pumping

80 APRIL 2010 water

Basement Pump Efficiency with Varying Flowrate

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Figure 2. Head vs Flow (H-Q) curves for motor speeds between 30 Hz and 50 Hz. systems and also to assess the feasibility of heat recovery schemes. This helps to reduce costs from water use, energy use, infrastructure works and ongoing maintenance costs.

Improving the water and energy nexus.

technical features


~ refereed paper

In both retrofit and new development situations, accurate water demands and modelling help to design the optimum system for the end use, and provide a sound basis for when it is necessary to choose projects based on capital expense. This can be done on a range of scales, with the level of detail required proportional to the size of system.

Energy Savings Efficiency Through Correct Pump Sizing Monitoring of water flow rate in a 26 storey apartment building revealed that the maximum flow rate required was well below the design level for the pump set. The basement pumping system consisted of two vertical multistage pumps with variable speed control which pressurised the reticulation system to a pressure setpoint. A second pump set was also located midway up the building to pressurise the top half of the building. There was no header tank. Pump efficiency curves were obt ained from the manufacturers and the data indicated that the pumps were operating inefficiently, despite the use of variable speed cont rol.

pumps & pipelines reduce power consumption significantly as the flow rate decreased.

consumption remains high across all flow rates encountered at this site.

The reason why the pump power consumption does not decrease as the flow rate decreases can be seen in the H-Q performanc e curves in Figure 2. These show that the actual performance of the pump is well outside the preferred operating range. In order to maintain the delivery pressure at the desired set-point of 60m head, the motor speed can only vary marginally over the operating range, from 37 Hz to 40 Hz. This is in the dotted-line area of the performance curves, indicating the pump is operating inefficiently. As a result, power

Similar inefficiencies were also identified for the upper floors pump set. Resizing both pump sets could result in a reduction of energy of around 330 kWh/d , saving around AUD$13 ,000 per year in energy costs. Over the life cycle of the pumps, around 10 years, the savings are estimated at AUD$170,000. The cost for purchase and installation of replacement pumps was estimated at between $50k and $65k, resulting in a payback of 4 to 5 years. The pumping system presented was not uncommon and preliminary

Power consumption in both pump sets was monitored, along with the flowrate, to confirm the pump efficiency. Monitoring indicated that power consumption did not vary significantly as the flow rate varied from peak flow in the mornings to low flow rates overnight. As a result, the pumps were operating with very poor efficiency. Figure 1 shows the relationship between flow rate and pump efficiency based on flow and energy monitoring data for the basement pump set. The red line in Figure 1 is pump efficiency and should be in the vicinity of 50-80% for a system well matched to the duty requirements. Instead, the efficiency rarely exceeds 10%. The power consumption in the pumps only varied between 12 and 15 kW while the instantaneous demand varied from 0.1 Us up to 5.5 Us, indicating that th e variable speed control was not able to

water APRIL 2010 81


~ refereed paper

pumps & pipelines investigations indicate that similar savi ngs are available at many high rise sites. These findings are currently being used to better match the pump size with expected water demand for buildings in the design phase.

Hydraulic Design

Cooling Towers

Pressurised supply

When considering the power consumption in high rise pumping systems, some observations on hydraulic design may be made. Many high rise hydraulic systems cou ld be modified at the design phase to enable a more efficient pumping system to be installed. For example, one high rise building in Sydney on which BMT WBM has worked has a variable speed pump wh ich delivers water to a tank on top of the bui lding with a smal l branch off the pressurised line to supply the top 5 floors, as shown in Figure 3.

~ Hot Water top 5 Floors

The pump set up required for the hydraulic system shown in Figure 3 is difficult to design in an efficient manner. High flow rates near 7 Us are requi red when fill ing the tank but the supply flow rate will be very low overnight as t he t ank will be mostly f ull. Overnight demand w ill be only t he top 5 f loors at a rat e of less than 0.3 U s. Also, if the cooling tower make up line has a slow dribble, as many do, the pump wi ll have to supply very low flow rates all of the time. Th e pump system needs to handle a head of near 80m while pumping at a rate well below its designed optimum range. In order to design an effic ient pumping system in this case, a small pump would have to be coupled with a larger pump. A spare large pump may also be required to allow for maintenance. Any sizing errors made in the design phase wi ll be compounded due to the high pumping head required . The pumping design cou ld be simplified and the efficiency improved by modifying the schematic as shown in Figure 4. The efficiency of the pumping system could be improved by drawi ng the supply for t he t op five floors from the gravity line downstream from the tank. A small variable speed pump or a fixed speed pump with press ure reservoir could be used to boost the pressure. The sizing of this pump is not as critical as that for the basement pump as it will not be doing much work due to t he low flow rates and low pumping head. The basement variable speed pumps cou ld be replaced with fixed speed pumps or set to operate at only one speed which w ill transfer the water efficiently at intermittent periods. These pumps should be easy to size as the requi red pumping head shou ld be accurately determined by the hydraulic designer.

Gravity! Header Tank

Cold Water top 5 floors

Low Rise Hot Water

Low Rise Cold Water

Large Variable Speed Booster Pumps

Figure 3. Simplified hydraulic schematic for a high rise building in Sydney.

Cooling Towers

Gravity f ed Small Variable Speed Booster pump

Hot Water

top 5 floors

Header Tank

/

Cold Water top 5 Floors

Low Rise Hot

Low Rise Cold

Water

Water

Implications for Fire Systems Some header tanks utilise the lower portion of storage for fire sprinkler water. This type of system s hould not be ret rospectively changed to have smaller pumps as the pumps were probably set to provide the flow rat e needed to run all t he sprin klers at once. Most bui ldings wi ll have a separate fire system which branch before the main meter and this is t he recommendat ion in AS2304.

82

APRIL 2010

water

Fixed Speed Pumps

Figure 4. A more efficient hydraulic schematic for a high rise building in Sydney.

technical features


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Figure 5. Location of warm condenser water pipeline in relation to cold water feed to the boiler for a high rise building in Sydney.

Heat Recovery from Cooling Towers Another innovative solution to optimising hydraulic systems is to exploit the synergistic benefits of cooling towers and water boilers. Cooling towers are designed to transfer heat from the build ing to the atmosphere, while boilers are used to heat water either through gas, solar or electric means. In high rise residential apartment buildings, the volumes and demands of hot water and cooli ng water can provide an elegant solution to assist both. Many high rise residential buildings in Sydney utilise packaged air conditioning units which reject thei r heat into a water circuit, the condenser water. Th is heat is then discharged to the atmosphere through a cooling tower. It is common for the cooling towers to be located adjacent to the boilers, usually on the rooftop . A good example of the proximity of the cooling tower to the boiler is given in Figure 5. Many of these syst ems run continuously over a 365 day period. Wh ilst the energy in the condenser water is low grade, there is still potential for significant energy recovery. The warm condenser water transporting heat from the building t o the cooling tower can be directed through a heat exchanger to preheat the water going to the boiler. The schematic layout is shown in Figure 6. This reduces the energy requirement of the boiler and reduces the heat load on the cooling tower. Monitored data from a sample of high rise buildings indicated a feed range of 12 to 65 kUd for boilers located adjacent to cooling towers. Using a conservative assumption of 26°C for the average c ondenser water temperature and 17°C for the town water supply, the energy available for recovery is 400 to 2, 100 MJ/d. This equates to a cost saving estimate of $2,300 to $12,500 p.a. A plate heat exchanger can be purchased for around $5,000 and it can be sized using the flow monitoring data and condenser pump specifications. Once installation is included, the payback for this investment will range from 1 t o 5 years (sites with higher hot water usage have the potential to recover more energy and will have shorter paybacks). Maintenance requirements for this system are minimal: the heat exchanger should require cleaning after around 5 years and the pump used to return condenser water exiting the heat exchanger back into the condenser circuit wi ll requ ire occasional servicing.

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water APRIL 2010 83


~ refereed paper

pumps & pipelines Challenges for Implementation Approval for capital works in high rise buildings must be obtained from the owners ' corporation. Unfortu nately, many high-rise buildings are saddled with significant maintenance issues such as lifts, plumbing and air-conditioning. As a result, fu nding for efficiency projects can be difficult to obtain, despite their attractive paybacks. Water and energy efficiency is now an important consideration during the design phase of new high rise buildings. Increasingly, developers are taking the extra step and applying to have their buildings certified under the "Green St ar" system. However, it should be recognised that there is a large stock of high rise buildings that have ample opportunities for improvement in efficiency. Trial sites for efficiency retrofits are needed to demonstrate the benefits of simple changes such as appropriate pump sizing and heat recovery. Successful trial sites can be used to encourage conservative and cash strapped owners' corporations t o invest in improving their buildings effic iency.

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system using available technologies can have profound cost impacts and should be tested in future building designs.

Acknowledgment The authors appreciate t he involvement of Melanie Schwecke from Sydney Water and the Sydney Wat er Every Drop Counts Business Program for their initiative to target this sector and financial contri bution to completing th is pilot and the constructive comme nts by t he reviewer, David Power, Technic al Manager, Hydraul ics , Beca.

Cold water supply to hot water system (12 to 65 kUday, 14-23°C)

monitoring and implementation. They have been involved in the field for over ten years and through innovations such as those described in this paper are producing wat er and energy savin gs for a wide range of clients. They are both part of the Sydney Office of BMT WBM P/L, Email reid.butler@bmtwbm.com.au. Melanie Schwecke is a project officer with the Sydney Water Every Drop Counts Project.

References AS 2304 and DR 073087 Water Storage for Fire Protection Systems Cartwright T, Moore C, Senathirajah K (2009) Demand data capture program for water efficient multi-units - present ed at IWA Efficient 09

The Authors

Cartwright T. (2008) Driving demands down BASIX and water usage in multi-unit developments - presented at IWA Efficiency 08

Reid Butler and Ashley Sneddon are environmental and chemical engineers specialising in water efficiency

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ADELAIDE

PeterE-Mlst

Owen Jayne 08 8348 1687 ojayne@wigroup.com.au

039883 3535 peverlstOwlgoup.com.au

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water

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Figure 6. Concept diagram of heat exchange between cooling tower water and hot water feed .

The advances in water efficient appliances and mandated water efficient fixtures in high rise apartments as a result of BASIX (in NSW) are leading to lower flow rates in the main hydraulic systems of these buildings. Design guidelines for pumping systems need to be reviewed to compensat e for the red uced flow demand so that pumps are not oversized and operating inefficiently. The results of this study revealed th e t rue rate of inefficiency found in one typical apartment building. The ramifications in t erms of energy and costs are large but simple changes t o the hydraulic planning and an understanding of the water demand in an efficient building wi ll inform future designs.

84 APRIL 2010

System

Hot water to the building

Warm condenser water from building to the _ cooling tower (24-35°C)

Conclusions

Another synergistic solution to energy loss was presented showing a way of using waste heat going to the cool ing towers to pre-heat boiler water. Again, simple adjustments to the hydraulic

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ITT Pump Efficiency Curves (2009) Seneviratne M. (2007) A Practical Approach to Water Conservation for Commercial and Industrial Facilities, Elsevier.

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technical features


skills shortages & education

THE H2OZ CAMPAIGN AN INDUSTRY-WIDE RESPONSE TO THE SKILLS SHORTAGE IN THE AUSTRALIAN WATER INDUSTRY Fiona Mackenzie, Industry Programs Coordinator, Australian Water Association The Australian water industry is facing a significant skills challenge. Research suggests that there could be a shortage of up to 40,000 workers by 2018 if this challenge is not effectively dealt with (ICEWarm, 2008). This situation has come about for a number of reasons including an increased demand for skills, an ageing workforce, increased complexity of water management technologies and a general lack of awareness about the career opportunities available in the sector. The critical nature of this issue is augmented by other challenges facing the industry in relation to water supply and climate change. These are issues which demand the attention and expertise of a robust workforce.

To address the skills challenge, there needs to be a dual focus and solutions via attraction and recruitment strategies combined with the retention and skills development of the existing water workforce. In the last few years, the water industry has initiated many national and state based and funded committees and projects. This article focuses on the implementation of the unique H2 0z careers in water campaign whilst the following paper by Sean Rhodes outlines a state based initiative: the SEQ Water Grid's Skills Formation Strategy. These represent a couple of case studies as to how the industry can mobilise industry efforts towards the crucial goal of maintaining ski lled water workers.

H2Oz careers in water campaign Australia faces a particularly high degree of labour shortage, however developed economies internationally are also affected (Zaidi and Cohen, 2003). Given international population growth, increased urbanisation and climate change considerations, skills shortages in water sectors around the world are particularly concerning. The H2 0z campaign is therefore internationally significant because it provides a concrete example of an innovative and visionary coordinated industry approach to a skills shortage. Propelled by industry and government research, support and consultation, there was a strong impetus to develop a business plan and budget for a new

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skills shortages & education representation from small councils to global consultancies to participate and benefit from the project. As a consequence, H2 Oz has the support of 30 organisation subscribers contributing over $300,000 in fu nding. Furthermore the importance and need for this initiative was formally recog nised when the Coalition of Australian Governments (COAG) cited the H2Oz campaign as 1 of the 3 fu nded initiatives within the National Water Skills Strategy produced in December 2009.

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water industry brand in June 2008. It was proposed that AWA manage the 3 year implement ation and promotion of a national H2 Oz careers in water campaign.

Th e structure included a dedicated AWA project manager, a reference group and a tiered organisation size funding model. This model encourages equitable

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The core of the H2Oz campaign is the website www .h2oz.org.au. The call to action ' it's great to work in water' underpinning all marketing activity is to encourage people to find out further details by visiting the website. The site contains: information on the Australian water industry, a comprehensive list of possible careers within the industry along with information on how to pursue such careers , job vacancies submitted by subscribing members, and a variety of other material such as interviews and vi deos designed to inform visitors about career opportunities in the water sector. The site is visually engaging, easy to navigate and contai ns a wealth of information about careers in the industry. For a new websit e, the website's traffic data is promising with over 13,000 visitors to date with a peak of 340 visitors on launch day. On average, visitors are spending over 4 minutes on the website which is also a solid indicator that the public are finding new or interesting information and exploring numerous pages on the H2Oz website.

Summary

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86 APR IL 2010 water

The H2 Oz campaign was the product of a great deal of intra-industry support and collaboration. Though the campaign is in its infancy - having been officially launched in mid -October 2009 - it has received very positive feedback from the industry and stakeholders so far as wel l as achieving greater media interest and coverage than expected. Whilst combatting a looming skills shortage of such magnitude and across an entire industry is no mean feat, if the water industry and government support for combined efforts cont inue, we are capable of rising to the challenge.

Bibliography International Centre of Excellence in Water Resources Management (ICEWaRM) National Water Skills Audit. June 2008. Zaidi, M. & Cohen, M. 'Globalization, skill shortages and surpluses in the new economy' , 13t h World Congress of the International Industrial Relations Association, Berlin, 2003.

technical features


~ refereed paper

skills shortages & education

SEQ WATER GRID STRATEGY FOR SKILLS FORMATION S Rhodes, C Elston, C Neilson, D Hardy Abstract This paper presents a work-in-progress case study of how a group of new water entities in a unique water supply arrangement in South-East Queensland are developing a joint response t o managing the transition to a new environment and tackling common workforce issues. The Water Grid is viewing its workforce challenges as an opportunity to demonstrate the strength of it s integrated model as a collective employer and build cooperation and comm itment among the Water Grid participants. The content of this paper is a sum mary of an investigation conducted for phase 1 of this joint response; the Wat er Grid skills formation strategy. The conclusions drawn from this initial phase will inform the project plan for phase 2 of the Water Grid skills formation strategy.

Introduction Queensland's solution to immediate and long-t erm water shortage issues in the State's south-east has involved rad ical reor ganisation of the region 's water sector to focus on building its institutional capacity to ensure wat er supply. The SEQ Water Grid (the Water Grid) is an int egrated syst em that has been est ablished to secure and efficiently manage South East Queensland 's water supplies. Th e four State-owned organisations involved are still adapting to this complex transformat ion, with capacity building as the goal at both an individual level and as an integrated supply chain. Li ke the rest of the Australian wat er sector, the welldocumented problem of skills shortages is an emerging risk for the Water Grid. Whi le extensive resources have been invested in physical assets, regulation and policy for the Water Grid it is timely to refocus on the Water Grid's most important assets its people. The Water Grid is viewing its workforce challenges as an opportunity to demonstrate the strength of its integrated model as a collective employer and build This paper was presented at Ozwater' 10.

cooperation and commitment among the Water Grid participants. Phase 1 of the skills formation strategy is now complet e. It involved analysing the workforce skills and demographic profile of the four St ate-owned entities of the Water Grid to identify the factors impacting skill req uirements for the Water Grid over the next five years, while also taking into consideration the broader impacts of the significant reform program on the affected organisations.

Project Background and Strategic Context Reform of the urban water supply arrangements in South-East Queensland

example of this is engaging Veolia Water to operate WaterSecure's advanced water treatment plants. This is another way to build capacity by importing expertise. About 2000 employees of State and local government-owned water businesses are in some way affected by the reforms. Many of these staff are transitioning from an established model of water service delivery to a new and very different one. The creation of four standalone statutory authorities, through mergers and new start-ups, has created opportunities but also some challenges and tensions. Successfully transitioning the workforce is critical to build the institutional capacity that policy-makers and stakeholders are seeking (Bridges, 2003).

In May 2007, on the back of the State's worst recorded drought, the Queensland Water Commission (QWC) announced the most significant changes to water management in the St ate's history. In its final report to the Queensland Government: Urban Water Supply Arrangements in South East Queensland, the QWC identified serious systemic weaknesses in the institutional arrangements for urban wat er supply in South-East Queensland (SEQ). The report indicated that these deficiencies were d irectly impacting on the ability of the water system to meet the needs of the SEQ community. Consequently, the State Government decided to introduce reforms to the way water services were provided in SEQ. The ensuing structural and regulatory reform culminated in the creation of the Water Grid. The Water Grid provides South East Queensland with climate dependent and climate resilient water sources, managed efficiently with a strong conservation focus. The focus has been on the transformation of the institutional arrangements, organisational structures, processes and systems that govern how urban water supplies in SEQ are managed. An aspect of the new arrangements has involved operations and maintenance agreements for specialist functions within the Water Grid. An

Water Grid skills formation strategy project: background and drivers In September 2008, shortly before the commencement of the new bulk water supply and interim pricing and operating arrangements came into place, the board chai rs and ch ief executive officers of the new State-owned water entities acknowledged the issue of widespread skills shortages in the water sector and the potential impacts of this on the institutional capacity of the Water Grid. In December 2008, the State-owned entities approved a proposal to implement a skills formation strategy for the Water Grid. The skills formation strategy is aimed at mitigating skills shortage risk and improving whole-of-Grid workforce capability. The anticipated benefits to the Wat er Grid are the improved management of risk and efficiency gains, while maintaining or increasing reliability of service. To be implemented over several phases, the skills formation strategy is designed to achieve this goal by gaining a commitment to whole-of-Grid skills formation; engaging in research to examine the effect of workforce capability on a secure and efficient water supply;

Building institutional capacity through people. water APRIL 2010 87


[Ill

skills shortages & education understanding workforce ski lls requirements at a whole-of-Grid level; identifying appropriate capacity-building initiatives to mitigate potential skills shortages in the Water Grid; and evaluating operating data to promote training improvements across the Water Grid. The scope for phase 1 of t he skills formation strategy project only included the new State-owned entities in the Water Grid. The second phase of the institutional reforms, involving the formation of new distribution and retai l entities from ten SEQ regional councils, is sti ll in progress. Given the relative immaturity of the three new distribution/retail businesses at the t ime of this study, they were not included in this initial phase of work.

Methodology To implement a ski lls formation strategy for the Water Grid, understanding the type of workforce required now and in the future is critical. Accordingly, a key process is to understand current and emerging business issues and the impli cations of future scenarios for each of the new water entities and the Water Grid as a whole. This project undertook an investigation of these issues by adopting a mixed method research approach including a literature review, archival document analysis and quantitative field research. The literature review focussed on themes in the literature about institutional reform and capacity bui lding with an emphasis on the water sector. The research was drawn from a current doctoral study at Queensland University of Technology to frame the implications of the institutional reforms on capacity building requirements. An analysis of secondary data sources provided recent information about the broader skills outlook of the water sector in Australia and factors impacting workforce supply. This was to provide a broader frame of reference for the project and underpin the development of some workforce assumptions about the Water Grid. The third technique applied in the investigation involved a human resource (HR) profiling survey of the State-owned entities in the Water Grid. The following sections outline the findings and analysis of this investigation. These provided a theoretically and empirically sound basis for the conclusions which will drive the scope and deliverables of phase 2.

88 APRIL 2010 water

refereed paper

SEQ WATER GRID MANAGER The SEQ Water Grid Manager is a Queensland Government-owned statutory body, responsible for managing the strategic operations and wholesale customer service for urban sector water, while balancing the needs of the community and the environment. The SEQ Water Grid Manager is one of the seven new water entities that replace the 22 t hat previously delivered water services in South East Queensland. The seven new entities include three council-owned businesses, to manage the retail supply of water t o customers (Queensland Urban Utilities, Unitywater and Allconnex Water) and four Queensland Government-owned bodies, to manage bulk water supply, treatment, storage and transport infrastructure (the SEQ Water Grid Manager, Seqwater, WaterSecure and LinkWater). The SEQ Water Grid Manager, which owns the regional water entitlements, buys water services from the following statutory bodies: • storage and treatment of bulk water from Seqwater • production of desalinated and purified recycled water from WaterSecure • transportation of bulk water from LinkWater. The SEQ Water Grid Manager sells raw, potable and recycled water products to councils, power stations, rural and industrial wholesale customers ensuring service requirements are accurately reflected in contracts and delivered to specification. In addition to this, the SEQ Wat er Grid Manager also: • manages catchment to tap water quality across t he entire Grid,

Review of the Literature on Capacity Building Institutional capacity building has been regarded by researchers and practitioners of natural resource management as an approach for mobilising change across a range of contexts and disciplines (van de Meene, 2008). Driven by the National Water Initiative, Australian states and territories have initiated substantial reforms of water management arrangements. However, the institutional reform and changes to the arrangements including wholesale changes to governance and ownership structures,

optimising control and monitoring at a system wide level • sets the whole-of-Grid asset performance standards to ensure all service provider assets function as designed • manages all financial transactions between service providers and w holesale customers • manages a risk management framework in partnership with Grid Participants • fosters and implements whole-of-Grid improvement projects in partnership w ith Grid Participants. Current SEQ Water Grid bulk water assets include: • 12 connected dams • 10 connected drinking water treatment plants • 3 advanced water treatment plants producing purified recycled water

• 1 desalination plant • 28 water reservoi rs • 22 bulk water pump stations

• 535 kilometres of potable bulk water mains South East Queensland's population is predicted to grow to 4.4 million by 2031. This , coupled with the effects of climate change, will impose heavy demands on water supply. The SEQ Water Grid Manager's holistic view of the water supply chain and wholesale customer needs means it can effectively maintain regional water security and quality, ensuring the region's water supply now and into the future. new performance measurement standards and systems and changes to management arrangements - have in themselves challenged the institutional capacity of affected agencies (Hillman & Howitt, 2008). According to the United Nations Development Program (2000), the quality of institutions is a key fact or influencing the impact of capacity building interventions. However, organisational transformation initiatives can therefore only be as good as the absorptive capacity of the affected organisations. That is, the organisations' ability to value,

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Figure 1. Percentage of workforce by job family (n=435 FTE). assimilate and apply new knowledge (Cohen & Levinthal, 1990) and commensurately, ski lls. Therefore, developing the capacity of the organisation to absorb and respond to change is a necessary instrument of institutional reform. The challenges to the institutional capacity of agencies and organisations impacted by reforms could go some way to explaining why the significant investment by governments in urban water reform have not delivered the expected dividends (van de Meene, 2008). Poor results from the reform of urban wat er supply arrangements in these other Australian case studies may in part be attributed to the scope or direction of capacity-bu ilding efforts. In the field of sust ainable urban wat er management, institutional capacity has been described as "the ability of the instit ution, from individuals through to organisations and legislative and policy instruments used, to undertake a task" (van de Meene, 2008, p.3). A five year study of institutional and organisational development of local government organisations in metropolitan Sydney found that the traditional approach of the State directing change through policy and regulatory reform did not lead to transformative and sustainable change in the implementation of sustainable urban water management (Brown, 2008). Brown (2008) concluded , that for widespread change to occur, effective institutional reform also needs to work on areas such as the cultural aspects of the institution.

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Figure 2. Percentage of workforce in each age category (n=435 FTE). Accordi ng to the Commonwealth Department of Education, Employment and Workplace Relat ions (DEEWR), (2008), the strength of the Australian labour market has contributed to skill shortages across many trades, professions, associate professions and management occupations. Occupations or ski lls in shortage that have implications for the water sector includes: engineers, ICT skills, engineering trades, electrical/electronics trades and construction trades. In 2005, the International Centre for Excellence in Water Resource Management conduct ed some industry research on behalf of the National Water Commission. The purpose was to identify gaps in current water management skills, training and education services and highlight where solutions were needed

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Another study in New South Wales found that the accumulated loss of key personnel during the institutional change process adversely affected the achievement of effective natural resource management. The loss of the knowledge, skill, physical and intellectual capacity was one of the attributes leading to the limited success of the reform (Hillman & Howitt, 2008). The findings of these few studies support a number of conclusions made about institutional capacity building in the areas of natural resource management and urban water reform. Most prominent is the view that while reform efforts to date have mostly focussed on policy and institutional structures, institutional capacity building needs to be broader in its approach and account for interdependencies between institutional reform , organisational strengthening and human resource development (Brown, 2008).

Water Sector Research This element of the investigation involved analysing recent labour market statistics around the broader context of the water industry, and a review of some industry sponsored workforce studies.

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Figure 3. Age profile by job family (n=435 FTE). to meet the needs of the Austral ian water industry, government and commun ity over the next decade. The study found an overall shortage of technical skills in the industry and further, due to wider portfolio responsibilities, a range of new skills was required. It also concluded t hat emerging water industry professionals may require training across a broad mix of discipli nes, but more so, to achieve a fu lly capab le workforce a range of nontech nical skills including communication, customer service, problem solving and the acceptance of 'life-long learning', are essential (National Water Commission, 2005). More recently, the Water Services Association of Australia (WSAA) sponsored an assessment of the ski lls shortage in the urban water industry. Based on a sample of 18 urban water utilities, the study determined that the most critical challenges for the urban water industry over the next ten years included: future workforce shortfall, ageing workforce, professional staff turnover, emerging skill req uirements, and remuneration (WSAA, 2008).

families and roles, and the age and gender profile of the workforce.

Sample The survey was limited to the Stateowned entities: Seqwater, LinkWater, WaterSecure and the SEQ Water Grid Manager. To varying degrees, all of the entities had a combi nation of "payroll' (permanent/part-time/casual) and workers engaged t hrough alliances or contract arrangements. Therefore two separat e surveys were conducted. The survey of "payroll-only" staff captured 435 full-time equivalent (FTE) employees. A second survey incorporated LinkWater All iance workers wh ich was an additional 65 FTEs. 70 Veolia staff working as operators for Wat erSecure were not included in this survey. For the intent of this paper a selection of the fi ndings of the "payroll-on ly" survey are outlined.

• Science and technical paraprofessionals (environmental, microbiology, chemist) represent the smallest occupational group at two per cent of the workforce. Age profile

Figure 2 present s the age profile of the FTE emp loyees in the survey. Key find ings: • More t han 56% of the FTE employees captured by this survey were aged over 40. • More than 28% of the FTE employees were aged 51 or above. Age profile by job role

Figure 3 displays the age profile of FTE employees for each job role in t he survey. Gender profile

A data collection tool in the form of a spreadsheet using a similar job role framework applied by WSAA (2008) was

Figure 4 displays the gender profile of FTE employees in t he survey. Key findings: • At nearly 73%, the gender profile of FTE employees is heavily skewed towards males.

Purpose

90 APRIL 2010 water

• 'White co llar' (administrative) roles (management, business support) make up nearly 38% of the total workforce.

Data collection

SEQ Water Grid Survey The third element of the investigat ion for phase 1 involved a HR profiling survey of t he State-owned ent ities. The purpose of t he survey was to enhance understanding of and compare findings from other research on workforce demographic characterist ics including distribution of employees across job

• Water industry operators (construction and maintenance, treatment plant operators) comprise the largest job family representing 32% of the total workforce, closely foll owed by those in management and business support roles.

Figure 5 presents a breakdown of the gender profile by job family in the survey.

Analysis of Phase 1 Investigation Male 72.82%

Figure 4. Gender profile (n=435 FTE).

Analysis of the primary data co nfirms that the State-owned entities, and likely the entire water sector in SEQ, face wh at

technical features


~ refereed paper

has been found in similar investigations: a significant ageing of its workforce. A number of key occupations in the Wat er Grid were found to be 'at risk' in terms of attrition over the next five to 10 years due to the high proportion of employees aged 51 or over. These included workers in the job roles of mechanical para-professionals, environmental engineers, electrical tradespersons, construction and maintenance and water treatment plant operations. This finding is all the more significant because they are based in core ope rational areas.

Workforce supply The study ascertained the proportion of the current workforce that will be employed within the Water Grid from 2009-2014 based on current headcount and projected resignation and retirement rates. This was calcu lated by ext rapolating workforce statistics from the primary and secondary data sources. Since accurate details of resignation or retirement rates were not available to this study, the calculations were based on

skills shortages & education assumptions applied in the workforce supply forecasts in WSAA's (2008) study, as outlined below. Forecasting assumptions

Utility resignation rates are lower than the Australian norm, with a uti lity median of 8. 1% compared with an all-Australian 2006 median of 14.7% (WSAA, 2008). In the WSAA survey, respondents said they expected their utility's resignation rate to remai n the same or increase slightly over the next few years. For the purpose of this project, the industry median resignation rate of 8. 1% has been assumed. According to WSAA (2008) a proportion of all resignees are likely to remain within the wat er sector. This is known as 'churn '. Another proportion of resignees will exit the sector entirely, known as ' leakage '. This investigation treated 20% of all resig nations as leakage, simi lar to the WSAA survey. WSAA's (2008) study reported an average retirement age of 60.5 years, which was consistent with an all-industry median of 60.1 years for 2006. Taking into account the impacts of the global financial crisis on superannuation funds

and plans by the federal government to lift the pension eligibility age to 67, th is project assumed an average retirement age of 63.5. Supply forecast to 2014

Figure 6 presents the workforce supply forecast to 2014 based on the assumptions described above. The key findings of this supply forecast suggests within five years (2014), approximately 23-24% of the Water Grid workforce will have retired. Although the turnover rate due to resignations is low in utilities compared to other sectors, it was estimated that by 2014 only 45% of the current Water Grid workforc e will still be employed in t heir original organisation.

Workforce demand A key facet of the dat a analysis involved estimating the size and profile of the workforce required by the Water Grid in the future taking into account predicted changes to the business and environmental factors. To accurately form these future business scenarios requires the input of leaders and key stakeholders. As this process had not commenced when

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skills shortages & education phase 1 of the project was being undertaken, the scope of demand forecasting was limited. Consequently, the project identified a preliminary set of business issues, or demand factors, which they believed were likely to influence workforce requirements in the Water Grid over the next five years.

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I40% It was determined by the - ,_ 1 - 1 - - · - - I35% project team that towards 30% 2014 the shape and context ,_ 25% of the industry will change: 1--1- · - - t - - - 1- 1 - - - 1 - - 1 - 1- ,- - - ,20% 1 - - 1 - - - - 1 - - 1 - - - 1the population wil l continue t o 1 - - 1 . - J I- I15% ,_ I- ~ - - >--- , Igrow; demand for water 10% >--I5% services will contin ue to 0% ..µ....__.........L.L,..L..L~'--1--'--'.........L.J..,-....a-,__,_....,_,...............................,,_.a...J..............._ .........L,-J,........L.L,..L..L~L..,-~ expand; organisations wi ll have to pursue new models of value creation; Government i I and the commu nity wil l expect more timely and l I detailed information; the impacts of 'climat e change' related policy wi ll need to be Figure 5. Gender profile by job family (n=435 FTE). met; energy red uction, water security, quality and Shared attraction, sourcing and human response, risk management and water environmental requirements will continue quality. resource development programs co uld to increase in scale and sophistication; also allow the State-owned entities to Initiatives such as whole-of-Grid productivity improvements wi ll be take advantage of collective 'purchasingprofessional and para-professional required as an alternative to a power', economies of scale, and further graduate (and undergraduate) programs diminishing existing labour skills supply; leverage this collaborative approach to could also improve attraction and and innovation in engineering and faci litate inter-entity transfers and crossretention of employees in the Water Grid technology must be leveraged to training programs. by enabling candidates to gain exposure maximise Water Grid efficiency and and training across all areas of the water To meet cu rrent and emerging return on the $6.2 billon+ investment. supply chain. business req uirements it was identified Over time, each Grid participant will Discussion that the State-owned entities cou ld likely make significant investments in implement joint training initiatives. This section discusses the implications developing the capability of its people. Options cou ld include development of for the Water Grid skills formation As partners in a non-competitive induction and training programs in strategy based on the investigation integrated supply chain, a joint approach common areas such as emergency conducted in phase 1 of the project. I-

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Th e findings from phase 1 of this project and similar workforce studies suggest the effects of diminishing labour supply requ ires a concerted effort and investment in the attraction, recruitment , development and retention of workers. The Water Grid faces the possibility of a large decrease in net workforce supply over the next five years. Accordingly, th e Water Grid must address the real issue of an increasing net shortfall in workforce supply. A whole-of-Grid approach to attraction, development and retention could reduce competition between the State-owned entities for human resources. Offering a critical mass of water industry jobs, industry skills development and research opportunities could optimise retention.

92 APRIL 2010 water

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Figure 6. SEQ Water Grid-state-owned entities: cumulative supply forecast to 2014.

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~ refereed paper

to capacity-build ing cou ld be a costeffect ive strategy for these four Stateowned entities. For each of the initiatives, further analysis is required to understand the requ irements, scope, deliverables, resource requ irements, implement ation and staging, coordinat ion, logistics and overall 'valueadd' to each organisation and the Wat er Grid.

Emerging demand The SEQ water sector is on a journey of major change. Over the next five years, fact ors that will drive business demand will include (although not excl usively): maturity of t he Water Grid, level of integration within the su pply chain, status of the institutional reforms, fi nal institutional model, risk management focus, st akeholder expectations, technological innovat ion, financial constraints, and government policy and legislation-specifically in relation to qualificat ion requirements, the indust rial relat ions environment and responses to cli m ate change. As the business d rivers change and the Water Grid evolves there will be requirements for new or improved ski lls, or enti rely new job roles. Planning for emerging workforce demand needs a medium to long-term operating vision and plan that includes a definition of stag es of maturity across the strategic, organisat ional and operational dimensions of the Water Grid. This is a crit ical prereq uisite for a properly al igned skill s formation st rategy.

Capacity for change Whi le the impact of t he institutional reforms on the workforce and demand factors for the individual State-owned ent it ies are not yet fully understood, the organisational environment in which t heir employees work is new or different as a resu lt of t he reforms. Successfully aligning the State-owned entities and their workforce within the new supply-chain model of the Water Grid is c ritical to t he success of the new mod el and achieving the level of inst itutional capacity that policy-makers and stakeholders are seeking. Implementing recruitment, t raining and other whole-of-G rid capacity-bu ilding initiatives will help facilitate necessary orga nisational and cultural changes.

Conclusions The f indings from phase 1 of the Water Grid skills format ion strategy project highlight that the Water Grid is presently,

skills shortages & education or will experience workforce challenges that mirror those in the broader water sector and ot her industries in Australia. The most pressing issues facing the State-owned sector of the Wat er Grid include an agei ng workforce, a diminishing supply of suitably skilled employees in high-growth occupations, the impacts of significant organisational changes resulting from the institutional reforms, changing jobs and emergi ng ski ll requirements and increasing levels of stakeholder and commu nity transparency and accountability. By acting collectively and co llaboratively, the State-owned entities have an opportunity to leverage w hat is an Australian first in water management, to attract workers in t he sector, and promote t he development of ind ustry skills, ed ucation and t rain ing offerings and investment in research. The ongoing development and implementation of a skills fo rmation st rategy for the State-owned entities offers benefits including a more highly skilled workforce across the water supply chai n, economies of scale and costsavings, accelerated adopt ion of new water supply arrangements and operating protocols, increased Water Grid resilience and risk prepared ness, and improved capacity to manage change. Investing in its people can help t he Water Grid realise the fu ll benefits of t he institutional reforms.

Acknowledgments Th e authors gratefully acknowledge the Chief Executive Officers of the Stateowned entities in the SEQ Water Grid for supporting and championing and this project.

The Authors

Sean Rhodes is the Prog ram Manager for Organisational Change and Capabi lity Development with the SEQ Water Grid Manager. Sean has more than 15 years experience in organisat ional development over a w ide spectrum of industry. He is presently completing a doctorate in organisational change and leadership t hrough the Centre for Learning Innovat ion at OUT. This work has provided some of the content for t his article.

Chris Elston is t he Organisational Development Manager for Seqwater. He has 30 years experience as a senior OD/ HR practitioner and has worked across a number of Industry Sectors including Fire Services, Energy, Flour Milling, Underground Mining and Health & Community Services. Chris Neilson is t he Human Resources Manager for LinkWater. Chris has over 10 years experience as a HR Manager in a range of industries including Const ruction, Telecommunications and Man ufactu ring. Dionne Hardy was formerly Corporate Development Manager for WaterSecure. She has over 10 years experience in Human Resources Management and Communications, in both operational and corporate environments

References Brown, R. R. (2008). Local institutional development and organizational change for advancing sustainable urban water futures. Environmental Management, 41 (2), 221-233. Bridges, W. (2003). Managing Transitions: Making the Most of Change. Cambridge, MA: Da Capo Press. Cohen, W. M., & Levinthal, D. A. (1990). Absorptive Capacity: A New Perspective on Learning and Innovation (Vol. 35, pp. 128152). Department of Education, Employment and Workplace Relations (2008). Australian Jobs 2008. Canberra, ACT . Hillman, M. , & How itt, R. (2008). Institutional change in natural resource management in New Sout h Wales, Australia: Sustaining capacity and justice (Vol. 13, pp. 55-66). National Water Commission (2005). Gaps in skills, training and education in water management, preliminary report, October, 2005. International Centre for Excellence in Water Resource Management: Canberra, ACT Mitchell, V. G. (2006). Applying integrated urban water management concepts: A review of Australian experience (Vol. 37, pp. 589-605). Queensland Water Commission (2007). Final Report to the Queensland Government: Urban water supply arrangements in South East Queensland (SEQ). Retrieved January, 2008 from http://www.qwc.qld.gov.au/ Urban+Water+Supply+Arrangements+Report van de Meene, S. (2008). Institutional Capacity Attributes of a Wat er Sensitive City: t he Case of Sydney, Aust ralia. Paper presented at the 11th International Conference on Urban Drainage, Edinburgh, Scotland, UK, 2008. Retrieved May, 2009 from: http://www.urbanwatergovernance.com/pdf/ 11 ICUD-vandeMeene-300331 a.pdf United Nations Development Programme (UNDP) (2000). 2000 Annual Report: Building Human and Institutional Capacity for Sustainable Development. Retrieved April 2009 from http://st one.undp.org/maindiv/bdp/dl/view.cfm ?Docld=177 Water Services Associat ion of Australia (2008). An assessment of the skills shortage in the urban wat er industry. WSAA Occasional Paper No. 21. March. Retrieved October 2008 from: https ://www. wsaa. asn. au/Pu bl icat ions/Pages/ OccasionalPapers.aspx.

water APRIL 2010 93


wastewater treatment

INTERMITTENTLY DECANTED AERATED LAGOONS IMPROVING NITROGEN REMOVAL Z Slavnic Abstract Intermittently decanted aerated lagoon (IDAL) is a technology employed to treat municipal wastewater. The technology is characterised by biological carbonaceous and nitrogen removal , while low phosphorus levels, when required , are usually accomplished by addition of chem icals. This paper will focus on improving biological nitrogen reduction, in partic ular the denitrification process.

Introduction Water corporations and local counci ls in Australia frequently employ IDAL technology to treat wastewater. With this technology carbonaceous pollutants as well as nitrogen are removed biologically, while the addition of chemicals ensures required phosphorus (P) removal. Proper oxygen control is essential in ensuring low ammonia and total nitrogen (TN) levels in the final effluent. This paper will address dissolved oxygen (DO) control during the IDAL's aeration cycles in order to improve overall removal of nitrogen, which is a key nutrient that causes eutrophication of receiving waters.

Nitrogen in Wastewater Nitrogen is a common pollutant present in domestic wastewater. It exists in the following forms: • Organic nitrogen: micro-biologically converted to ammonium form in the process known as ammonification. • Ammonium form (N Hi NH4 +): microbiologically oxidised to nit rite/nitrate in the process known as nitrification. • Nitrite (NO 2-) and nitrate (NO3-): microbiologically reduced to nitrogen gas (N2 ) in the process know n as denitrification. Nitrogen is a key macronutrient, and as such is responsible for overfertilisation of receiving waters. This is manifested by excessive plant and algal growth (eutrophication), in particular during warm seasons. In addition, ammonia depletes oxygen concentration,

94 APRIL 2010 water

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and in higher concentrations is toxic to many aquatic species. For those reasons, nitrogen removal from wastewater is these days commonly req uired before the effluent can be discharged into the environment.

IDAL Operation The IDAL process is characterised by three intermittent operating cycles, i.e. aeration, settling and decanting, all taking place in a single tank. Therefore, the tank performs a function of a bioreactor as well as of a secondary clarifier. The aeration phase provides necessary oxygen for BOD/COD removal and biological oxidation of ammonia (NH 3) into nitrites (NO2 ) and nitrates (NO3) by nitrifying micro-organisms (nitrifiers). As a rule of thumb, the DO concentration required to be maintained throughout the aeration phase is 2 mg/L. Switching off the aerators (surfac e or diffused) at the end of aeration cycle marks the start of settling phase. Th is allows the biomass to settle, hence the IDAL tank serves as a secondary clarifier separating solids

(biomass) from liquid. The clear supernatant is then decanted by lowering decant troughs (decanting phase) and further treated, e.g. tertiary clarification for further P reduction, fi ltration, disinfection, etc. During the settling/ decanting phase anoxic conditions are created (i.e. absence of dissolved or free oxygen) allowing denitrification to take place, that is nitrites/nitrates are biologically converted into nitrogen gas (N 2) which bubbles to the surface and into the atmosphere. Upon completion of the decanting phase, aeration is restarted and this cycli ng is repeated throughout the 24 h period. Duration of a complet e cycle (aeration, settling and decanting) can vary, but there are typically 6 to 8 cycles per day (Figure 1), w ith aeration being 50 % of a single cycle's duration. The influent is fed conti nuously into the IDAL tank and waste activated sludge (WAS) is usually removed during the aeration phase, as that ensures uniform wasti ng of the excess biomass.

Conventional Aeration Phase

Better nitrogen removal achieved by modifying the aeration software.

With the conventional aeration phase, the aeration is contin uous, i.e. once started, the aerators are kept running all the time till the end of the aeration phase, as can

technical features


wastewater treatment be seen from Figure 2a). Obviously, the DO concentration is always > 0 mg/ L and typical ly ranges from 1 to 3 mg/ L, depending on the aerators control. For example, using surface aerators with variable speed drives can maintain DO levels around 2 mg/ L and ensure unhindered nitrification.

35 3

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Modified Aeration Phase 15

Given that during the aeration phase ammonia is fully nitrified , i.e. almost non-existent, it is obvious that if improvements in the TN concentration are t o be gained, one needs to focus on nitrites/nitrates reduction. One way of doing this is to modify the aeration phase in order to facilitate denitrification, hence achieve fu rther reduction in nitrites/ nitrates concentration without impacting on ammonia removal (i.e. nitrification). This has been successfully implemented by Julian Briggs, CH2MHill's Principal Technologist, at t he Sydney Water's West Camden STP (Note: The author is not aware of any other IDAL plant where this strategy has been put in place). The difference between the conventional aeration phase and modified aeration phase can best be seen from Figure 2. Un like the conventional aeration phase (Figure 2a), with the modified aeration phase (Figure 2b) the aeration is ceased on two occasions for a short period of time (i.e. 0 - 15 minutes, depending on the di urnal flows). Th is allows the biomass to consume free oxygen, as can be seen by the DO levels quickly dropping down to O mg/ L, hence creating anoxic conditions necessary for the onset of denitrification. With this modification nitrate concentration in the IDALs effluent was lower by 2-3 mg/ L when compared with the effluent with

05

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Figure 2a. DO Profile - conventional.

conventional aeration phase. Naturally, this reduces the TN levels for the same amount, as there was no observable impact on the ammonia co ncentration, i.e. the ammonia levels remained unchanged (virtually zero) irrespective whether the aeration was continuous or not. Another way of improving removal of nitrates in the IDAL plants, in the author's opinion , is to modify the settling/ decanting phase. This would involve restarting the aeration for a short period (e.g. 30 or so seconds) during the settling phase to resuspend the settled biomass and bring it again into contact with nitrates. Namely, as the biomass settles two distinctive layers are formed within a short period of ti me, i.e. clear supernatant and sludge blanket (settled biomass). Virtually, denitrification cannot continue in the supernatant layer due to the absence of biomass, w hich has already settled. Resuspending the biomass by a short re-aeration, a techn ique sometimes employed in

sequential batch reactors (SBRs), eliminates this problem. Obviously, implementing this option will req uire modifying the duration of settling and decanting times to ensure the biomass had sufficiently settled to prevent its carryover once the decanters are lowered. As is the case with the modified aeration, experience suggests this t o be feasible during the off-peak cycles only.

Conclusion The modified control of aeration phase has resulted in superior nitrogen removal than the conventional IDAL aeration control, as 2-3 mg/ L of additional reduction in nitrates was consistently accomplished at West Camden STP. Another strategy for improving nitrogen removal involves resuspending the biomass during a settling phase. It is therefore suggested that IDAL processes should be designed in the first instance to incorporate either feature (or even both). As there is no additional equipment requ ired th is can also be implemented at the existing IDALs plants with minor costs associated with software modification.

The Author 2.5

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Dr Zoran Sl avni c (PhD, MBT, MEngSc, BMechEng) has 29 years experience in design, construction, commissioning , O&M and asset management in the water industry. He is Commissioning Manager with Laing O'Rourke (Australia). Email: zslavnic@laingorourke.com.au

water APRIL 2010 95


wastewater treatment

[ii

refereed paper

WETALLA PLANT SETS NEW STANDARDS FOR EPBR DESIGN AND OPERATION P Griffiths This paper, originally titled "Innovation during the optimisation phase of an alliance - identification of new technologies and improved control for BNR plants" won the Michael Flynn Award for best platform paper at Ozwater'10.

"You can wait a very long time to do a great project with a great team. I don't have to wait any longer, this experience has been the best thing in my career" The optimisation phase of an alliance provides incentive and opportunity for improvement and innovation. Most importantly, it provides you the time to identify and achieve these objectives. Then all you need is the right Team that provides the encouragement and support. Peter Griffiths

Abstract Many recent wastewater treatment projects within Austral ia are delivered under the Alliance type delivery model. Most of these Alliances include a two year optimisation period. The optimisation period presents tremendous opportunities to further develop, refine and research the treatment processes involved resulting in improved design of future plants or potential development of new technologies. The Wetalla Water Alliance was chartered with providing a 120,000 Equivalent Person (EP) Biological Nutrient Reduction (BNR) Plant. The final plant incorporated biological treatment for nitrogen and phosphorus removal , gravity thickening of waste activated sludge, aerobic digestion, solids dewatering and solar drying of dewatered biosolids. There was therefore

Outstanding performance achieved through Alliance Optimisation. 96 APRIL 2010 water

Figure 1. Original Stage 4 (left) and new Stage 5 (right) with the aerobic digester integrated into the bioreactor structure for the Stage 5 plant. The two small gravity thickeners are adjacent to the Stage 4 Bioreactor. The new solids dewatering building and solar drying hall are top left with the lime clarifier. considerable opportunity to refine and develop a range of wastewater treatment technologies and their integration into a plant. A number of the refinements developed were unexpected and have identified opportunities for more sustainable treatment plants. Other refinements, such as low nitrous oxide emissions, although not specifically designed for, were not unexpected once demonstrated.

Introduction The adoption of a two year process optimisation period for All iance type projects in the wastewater treatment industry provides the opportunity for designers to confirm or modify their design assumptions, further refine their understanding of the biological processes involved, gain a greater understanding of the interaction and

operation of critical mechanical equipment and review, refine and optimise automated control functions. The Wetalla Water Reclamation Facility (WRF) upgrade project was undertaken as an alliance between Toowoomba City Council (now Toowoomba Regional Council} and the CH2M HILUBarclay Mowlem (now Laing O'Rourke Australia) Joint Venture. The lessons learnt from the Wetalla WRF Optimisation period provided details for improved design and performance of BNR plants in conjunction with simplified operation. The project resulted in a low capital cost plant achieving very low effluent nutrient concentrations without supplemental chemical dosing and demonstrating highly energy efficiency with very low nitrous oxide emissions. Operation is very simple with minimal adjustments to aeration control parameters, sludge

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wasting and disinfection. Considering these factors and the high influent nutrient concentrations treated, the plant potentially represents the current "state of t he art" for BNR technology and provides the basis for future development and refinement.

Table 1. Influent Characteristics (2008/2009)

Project Description

Phosphorus

The project involved the optimisation of the existing 120,000 EP Stage 4 BNR Plant (commissioned 1995) and augmentation of capacity with the Stage 5 120,000 EP BNR Plant. The intention was to provide an integrated 240,000 EP Plant meeting stringent effluent quality guidelines of 5 mg/ L Total Nitrogen and 1 mg/L Total Phosphorus. As the plant receives trade wastes with elevated concentrations of non-biodegradable Total Kjeldahl Nitrogen (TKN), the effluent Total Nitrogen requirement was modified for the competitive alliance tender phase of the project to 3 mg/L nitrate-nitrogen plus nitrite-nitrogen plus ammonianitrogen. Post award of the project, the alliance has strived (and substantially succeeded) to meet the target of 5 mg/ L Total Nitrogen although not directly within t he Alliance Scope. This has proven to be a major benefit to Toowoomba Regional Council (TAC) as the expense of implementing methanol dosin g and the ongoing costs to be incurred have been avoided. Similarly, the plant employs Enhanced Biological Phosphorus Reduction (EPBR) technology to eliminate alum or ferric dosing.

B0D5:TKN

The influent characteristics to the plant are heavily influenced by trade waste discharges including those from a tannery and from a yeast manufacturing plant. Typically, the waste is approximately twice the strength of domestic sewage however it shows considerable variation. The range of influent characteristics experienced are summarised in Table 1. The influent TKN concentrations were considerably higher then initially

Parameter 5 Day Blochemlcal Oxygen Demand (B0D5) Chemical Oxygen Demand (COD) Total Suspended Solids (TSS) Total Kjeldahl Nitrogen (TKN)

Median

Range*

550 mg/L 1125 mg/L 550 mg/L 109 mg/L

429-700 mg/L 894-1663 mg/L 398-685 mg/L 82-126 mg/L 10.6-15.4 mg/L 4.0-6.8

13.2 mg/L 5:1

• Range given as 5th percentile to 95th percentile composite samples anticipated (average of 80 mg/L originally projected). Furthermore, during the design and construction period, the dairy and the abattoir closed down removing sources of organic carbon waste loads t hat would aid denitrification.

Plant Description The original Stage 4 Plant was a BNR plant based on the Variation on the Modified University of Cape Town (Variation on MUCT) process configuration (Griffiths and Tonkovic, 1990) with the process design originally undertaken by the author. The design incorporated gravity thickening of waste activated sludge (somewhat unconventional for a biological phosphorus reduction plant), aerobic digestion of thickened waste activated sludge, belt filter press dewatering and lime treatment of dewatering filtrate to remove phosphorus released during the aerobic digestion process. Final effluent disinfection was by gaseous chlorine. Although the Stage 4 plant had some limitations in performance due to selection, configuration and operation of some items of mechanical equipment, the process design review some ten years later demonstrated that the basic infrastructure in terms of major process units and mass fractions provided were still the most appropriate. The Stage 5 plant was therefore principally a duplication of the Stage 4 plant with some modifications. The major modifications were:

• Provision of dedicated blowers for the aerobic digesters • Replacement of diffused air aeration with submerged turbine "Oki" aerators • Replacement of Waste Activated Sludge centrifugal pumps with rotary lobe pumps. • Provision of scum harvesters • Provision of a solar drying hall • Provision of updated control philosophies. The plant is shown in Figure 1 with the process configuration shown schematically in Figure 2. Raw sewage is discharged directly to the anaerobic zone without primary sedimentation or pre-fermentation. Due to the high influent TKN concentrations, it was considered essential at the time of design to provide an internal recirculation rate (A Recycle) of the order of 50 t imes ADWF in order to achieve the required effluent total nitrogen concentrations. Such high internal recirculation rates had been identified as being permissible in BNR plants based on the revised denitrification models developed (Griffiths, 1994) fol lowi ng on from the investigations carried out by the University of Cape Town (Clayton et al, 1989). The revised model was first applied and confirmed at the Merrimac Stage 4 plant in 1995 where A Recycle rates of 20 times ADWF were successfully used to achieve an effluent total nitrogen concentration of less t han 3 mg/L (Griffiths, 2009) with stringent dissolved oxygen control.

Optimisation and Lessons Learnt A Recycle

A1

Retum Activated Sludge Recycle

Figure 2. Process Configuration of Bioreactors showing Variation on MUCT (Pre-anoxic zone in R Recycle stream) and Low DO/ De-aeration Zone on A Recycle.

Nitrogen reduction - low dissolved oxygen (de -aeration) zone The high internal recirculation rate utilised at Wetalla of 50 t imes ADWF introduced its own problems. Based on experience at the Bendigo and Merrimac BNR plants, it was identified that a high dissolved oxygen concentration of the order of 2.5 to 3 mg/L was required at

water APRIL 2010 97


wastewater treatment the end of the aerobic zone in order to achieve good enhanced biological phosphorus reduction. However, recirculation of 50 times ADWF with a DO concentration of 3 mg/L to the anoxic zone would theoretically aerobically consume over 450 mg/L of biodegradable COD and this wou ld no longer be available for denitrification. As it had been previously identified that an ascending dissolved oxygen profile appeared optimum for the enhanced biological phosphorus removal process, it was determined for the Stage 4 plant that the A Recycle would be drawn from a lower dissolved oxygen zone as shown in Figure 3 (Cell A3 of the aerobic zone), passed to a further aeration zone (Cell A4) with a similar dissolved oxygen concentration to the lower dissolved oxygen zone (Cell A3) prior to discharge to the anoxic zone. The main flow to the clarifiers passes from the lower dissolved oxygen zone (Cell A3) to a high dissolved oxygen concentration zone (Cell AS) where phosphorus uptake is maximi sed. The process configuration as adopted for Stage 4 was a compromise. Any ammonia not oxidised to nitrate by the end of the low dissolved oxygen concentration zone (Cell A3), would be passed to the high dissolved oxygen zone (Cell AS) and would be oxidised to nitrate without any opportunity to denitrify this material. This became a major consideration in optimisation of the Stage 4 and Stage 5 plants. During the initial operation of the Stage 4 plant, the plant Superintendent, Mr John Paulger, identified that the cell prior to the anoxic zone (Cell A4) could be operated at very low aeration inputs; just sufficient to maintain solids in suspension; without inducing phosphorus release. This went against the experience at the Merrimac Stage 4 BNR plant where a drop in dissolved oxygen concentration along the aeration train appeared to either induce phosphorus release or inhibit phosphorus uptake resulting in elevated effluent phosphorus concentrations of the order of 5 mg/L. It was t hought that operation of the initial aeration cells at Wetalla at dissolved oxygen concentrations of the order of 1 to 1.5 mg/L, resulted in only a low level of phosphorus uptake and thus any potential for release in the low dissolved oxygen concentration Cell (A4) was minimised. This hypothesis was tested at the Morpeth BNR Plant which does not have a de-aeration zone. At Morpeth, the first three of the four aeration cells were operated with an ascending DO profile of

98 APRIL 2010 water

[ml

refereed paper

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Figure 3. Effluent Nitrate Nitrogen concentrations demonstrating impact of reduced dissolved oxygen carryover when internal recirculation adjusted. 1.5, 2.0 and 2.5 mg/L. The fourth aeration cell was then operated with sufficient air flow to just keep solids in suspension. In this configuration, the performance improved and achieved effluent phosphorus concentrations of less than 0.5 mg/L. This was contrary to the theory that release would be minimised if only low level phosphorus uptake had occurred. Clearly this area of operation of biological phosphorus reduction systems requires further research. Based on the operational experiences of Mr Paulger, aeration cell A4 was operated with no aeration and functioned purely as a de-aeration zone. The retrofitting of "Oki" submerged turbine aerators to the Stage 4 plant, permitted both the Stage 4 and Stage 5 plants to operate with the de-aeration zone completely un-aerated. To minimise the potential for ammonia bleed through to Cell AS, the sludge age was increased slightly from the design value of 15 days to 17 days. Full nitrification was then achieved by the end of aeration Cell A3 thus maximising the nitrogen removal potential. Operation of Cell A4 as a de-aeration zone resulted in reduced dissolved oxygen carry over to the anoxic zone and improved nitrogen removal. Although the nitrogen removal was very good given the high influent TKN concentrations, effluent Total Nitrogen concentrations remained in the range of 5 to 8 mg/L.

Nitrogen reduction - independent control of inte rnal recirculation rate (A-Recycle) This internal recirculation rate of 50 times ADWF made allowance for diurnal

nitrogen load variations. However, continuous on-line monitoring of effluent nitrate concentrations at the Morpeth BNR Plant had demonstrated that diurnal variations in the effluent nitrate concentrations were minimal. This is attributed to " load equalisation" in the main anoxic and aerobic zones where the detention time based on ADWF is of the order of 18 hours. With the high internal recirculation, the combined anoxic and aerobic zones approach "complete mix" conditions thus achieving effective load equalisation. Based on the presumption that the internal recirculation rate was only requi red to address average daily influent nitrogen loads rather than peak diurnal nitrogen loads, it was determined to turn off one of the four A-Recycle pumps in Bioreactor 1. Based on grab samples, Bioreactor 1 had continuously demonstrated higher nitrate concentrations than Bioreactor 2. The impact of turning off the A Recycle in Bioreactor 1 is presented in Figure 3. The fourth A Recycle pump in Bioreactor 1 was turned off on 22nd June 2008. The nitrate concentration in the grab sample for Bioreactor 1 decreased to similar concentrations as Bioreact or 2 and then continued to decrease to be consistently less than Bioreactor 2. Based on the improved performance for Bioreactor 1, it was determined to turn off the fourth A Recycle pump in Bioreactor 2. This was undertaken on 13th August 2008 with improved nitrate removal in Bioreactor 2. The overall 24 hour composite samples for the plant also demonstrated a marked improvement and far more stable effluent concentrations.

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[i]

wastewater treatment

refereed paper

The reduction in A Recycle enhanced biological 0.3 phosphorus reduction. The flow rate from approximately 50 ..J Variation on the Modified UCT times ADWF to less than 40 010.25 E times ADWF and the process configuration has C 0.2 improvement in effluent nitrate therefore proven very robust .2 ~ 0.15 and effective in protecting the nitrogen concentrations achieved C 0.1 anaerobic zone from nitrate demonstrates the impact of GI () leakage. dissolved oxygen carryover even S 0.05 with a de-aeration cell provided. 0 Solids settling 0 This supports previous research a, a, a, a, a, a, a, a, a, 0 0 0 0 0 0 0 0 0 The solids settling that found that there are 0 0 0 0 0 0 0 0 0 £:! £:! £:! £:! £:! £:! £:! £:! £:! characteristics achieved has a considerable advantages in ~ ii; (D ;::: co en 0 ~ r-1 major impact on capital costs being able to independently (secondary clarifier size control the A-Recycle separate 1......- Effluent Total Phosphorus (Composite) required) and operating costs from aeration input (Abusam et (return activated sludge al, 2002). With this independent Figure 4. Effluent Phosphorus ex Clarifiers. pumping required). The Wetalla cont rol it has been possible to BNR Augmentation was control effluent nitrate Plant when strict attention was paid to designed specifically to achieve good concentrations lower levels with effluent calibration of the dissolved oxygen solids settling based on the principles ammonia nitrogen concentrations probes; particularly for the calibration of outlined previously (Griffiths and Stratton, continuously less than 0.05 mg/L. This the "zero" reading for the probes as 1997) that followed on from the work has been achieved without the need for against the usual calibration at done by the University of Cape Town supplementary substrate dosing. saturation. The use of dissolved oxygen (Casey et al. 1993). In order to achieve However, variations in influent BOD 5 to probes based on the galvanic cell good solids settling, it was considered TKN ratios due to trade waste principle that have a very stable "zero" essential to minimise ammonia fluctuations still impact on performance. reading has aided the excellent level of co ncentrations in the A Recycle. Biological phosphorus reduction Adjustment of the sludge age and the phosphorus reduction achieved at Biological phosphorus reduction has dissolved oxygen concentration set Wetalla. been excellent since commissioning points in Aeration Cells A1, A2 and A3 The low effluent phosphorus permitted this objective to be met. Both (Figure 4). Generally the effluent Total concentrations have been consistently Bioreactors at Wetalla have Phosphorus concentration has been less achieved providing confidence in the demonstrated consistent and very good than 0.2 mg/L. The filtered orthoprocess to provide robust biological phosphate has been measured on two solids settling with SSVl's of less than phosphorus reduction particularly given 100 mUg compared t o more typical occasions and was less than 0.05 mg/L. the variability in influent phosphorus values of 120 mUg or more Similar This suggests that the inclusion of concentrations. Periods of increased results were previously demonstrated at tertiary filtration at the Wetalla WR P effluent phosphorus concentrations have the Merrimac Stage 4 BNR plant where would result in an effluent phosphorus been experienced and these were ammonia concentrations of less than 0.1 concentration close to the limit of associated with either prolonged power mg/ L were continuously achieved in the biological availability (approximately failures or prolonged periods of wet A Recycle. 0.035 mg/ L as phosphorus). This weather flow. excellent performance can be attributed With this good solids settling, the plant to the high dissolved oxygen cell at the A further attribute of the plant in could theoretically accommodate rise end of the aerobic zone. The findings achieving a high degree of biological rates of over 1.6 m/hr. However, based here that elevated dissolved oxygen phosphorus reduction is the process on the existing inlet pipe and outlet pipe concentrations of the order of 2 to 3 configuration adopted. As demonstrated hydraulics for the Stage 4 secondary mg/L are required at the end of the in Figure 3, periodic high effluent nitrate clarifiers, the plant throughput has been aerobic zone in order to achieve levels of up to 8 mg/L were experienced. limited to approximately fou r times consistent low effluent phosphorus Similar nitrate concentrations would have Average Dry Weather Flow (ADWF) and concentrations of less than 0.3 mg/L is been experienced in the Return Activated this results in a rise rate of 1.2 m/hr. The supported by recent overseas research Sludge flow as the plant is operated with plant has, in reality, operated at slightly (Johnson et al. 2006). higher rise rates without exceeding its minimal if any sludge blanket in the effluent solids limit of 15 mg/L. Operation secondary clarifiers. The return of this It is worthwhile noting that similar at these high rise rates permits high effluent phosphorus concentrations were concentration of nitrate directly to the throughputs for clarifiers and reduces if achieved at the Merrimac Stage 4 BNR anaerobic zone would completely inhibit

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water APRIL 2010 99


wastewater treatment not eliminates the need for raw sewage or screened and degritted sewage bypass. An inflow of greater than 4 times ADWF is projected to occur less than 4 hours per year. Thus a high degree of environmental prot ection can be provided without excessive capital cost or area requi rements.

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Each bioreactor at Wetalla has its own dedicated aerobic digester. The digesters are both divided into four approximately equal sized compartments. The digesters are operated on a "fill and draw" basis to compensate for periods when the dewatering facility is not operating.

Nitrous oxide emissions

To minimise the recirculation of nitrate and/or ammonia from Nitrous oxide is a greenhouse the aerobic digestion process gas with approximately 31 O times Ammonia Nitrogen -+- Nitrate Nitrogen ..,._ Phosphorus back to t he main treatment the impact of carbon dioxide. process, each cell of the aerobic The nitrous oxide emissions at Figure 5. Aerobic Digester Nutrients. digester was operated with the Wetalla WRP were intermittent aeration . By independently measured (Foley hydrophobic substrates from the influent, providing accurate aeration control, the 2009) and found to be equal lowest of ammonia nitrogen concentrations in the the formation of biological foams cannot the plants measured in Australia at 0.006 filtrate from the last cell of the aerobic be prevented given adequate sludge age. kg Nitrous Oxide per kg nitrogen digester can be controlled to generally Seasonal variations in the severity of denitrified (range for the plants measured within the range of 0.2 t o 0.3 mg/L w ith foaming will generally be experienced was 0.006 to 0.235 with an average of nitrate nitrogen controlled to less than 0.035 kg). due to variations in hydrophobic 0.2 mg/ L (Figure 5). interactions. Although the nitrous oxide emissions The major finding from operation of the were very low, it was not completely The foam forming bacteria therefore aerobic digester with accurate aeration unexpected. The Wetal la Plant was actually fulfil an ecological niche in the control was that, not only were nitrogen designed to minimise filamentous bulking treatment process in that they remove in the filtrate from the end concentrations and the presence of filamentous bulking and degrade fats, oils and greases that of the digester controlled to very low bacteria has been associated with nitrite would otherwise be discharged in the levels, phosphorus concentrations were formation (Casey et al 1993). In turn, the effluent. The issue then becomes not one also controlled to very low levels of less presence of nitrite has been associated of controlling the formation of biological than 2 mg/L phosphorus, (equivalent to with the generation of nitrous oxides foams rather one of managing the an increase in the raw sewage influent (Alinsafi et al, 2008). Thus, the lack of biological foams. phosphorus concentration of less than nitrite at the Wetalla WRP suggested that 0.06 mg/L). This was a major and A foam barrier was provided between low nitrous oxide emissions co uld be extraordinary finding. The find ings were expected and were, in fact, achieved. aeration cell A3 and aeration cell AS. This even more startling given the good diverted separated foam into cell A4; the Waste activated sludge wasting and Volatile suspended solids (VSS) de-aeration zone. A foam harvester was thickening destruction of 30% (average) during provided at the end of this cell to remove d igestion. In general, the literature has the separated foam. The foam is recommended against the use of gravity Modelling of the plant suggested that removed at approximately 2.5% w/w thickening of the waste activated sludge approximately one third of the solids and pumped to the aerobic from enhanced biological phosphorus phosphorus removed would be released digester. Foam that passes to the reduction systems (WAC, 1984). during the aerobic digestion process. secondary clarifiers is collected using However, it was determined that if the During periods prior to implementing conventional skimming mechanisms with thickener was operated as a clarifier accurate aeration control, phosphorus submerged beaches. The separated and (continuous feed and with continuous concentrations of over 300 mg/L have collected foam is pumped back to the and rapid solids removal using a tapered been experienced (theoretical maximum bioreactor where it is removed as a much spiral scraper) thus preventing generation if all phosphorus released of 500 mg/L). thicker product by the foam harvester. of a sludge blanket, then the system The minimisation of phosphorus should operate without release of The use of the foam harvester release was not due to struvite formation phosphorus. This has proven to be the dramatically red uces the mass of or calcium precipitation (lime dosing to case and the overall system has proven biological foam discharged to the the digester during a period of high very effective and reliable. secondary clarifiers and maintains it at phosphorus release was trialled with no levels that the scum beaches on the Biological foam management benefit-Figure 5). From microbiological clarifiers can effectively remove. This analysis, it appears that residual polyThe generation of biological foams in prevents foam accumulations on the in the phosphorus hydroxy-alkanoates activated sludge plants that achieve secondary clarifiers and therefore accumulating organisms may be nitrogen removal is inevitable. The foam eliminates the laborious task of hosing consumed during aerobic digestion forming bacteria have a hydrophobic down the surface of t he secondary thereby taking up phosphorus released surface layer and thus utilise clarifiers with the resultant increased by the death and lysis of some of the hydrophobic compounds such as fats, phosphorus accumulating bacteria and discharge of solids to downstream oils and greases as substrate (Stratton et other organisms. al., 1998). As it is impossible to remove facilities or the environment.

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100 APRIL2010

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technical features


wastewater treatment

~ refereed paper

With retention of phosphorus in the digested solids, lime dosing of the dewatering filtrate could be eliminated thus reducing operating costs and significantly simplifying operations. Odours associated with the lime dosing and dewatering of lime sludges were eliminated. Recovery of phosphorus in the biosolids provides additional benefits for agricultural reuse as all of the phosphorus is available for crop uptake. Chemical precipitation of phosphorus that would otherwise be used tends to limit the bio-availability of phosphorus for agricultural purposes.

Power consumption Power consumption has been very low at the plant. This can be attributed to several factors. Provision of the high dissolved oxygen zone at the end of the bioreactor minimises aeration demand by providing this high dissolved oxygen concentration where oxygen demand is lowest. The submerged turbine "Oki" aerators are usually high power demand devices as, during periods of low air flow, the impeller is mixing a high water content mixture rather than a high air content mixture. The turbines were fitted with variable speed drives and operated for constant torque thus minimising power demand under low air flow conditions. Power consumption was monitored at less than 2.4 kWhr per kg BOD5 including aerobic digestion. This compares favourably with less complex plants where power consumption in the range of 3 to 4 kWhr/ kg BOO5 have been monitored and the industry "good practice" of 2.5 kWhr/ kg BOD5 . The only difference if treating "domestic strength" sewage at Wetalla would be the operation of two additional secondary clarifiers and associated Return Activated Sludge pumps that would increase power consumption by less than 2%.

Summary and Conclusions The process optimising period for the Wetalla Plant has demonstrated a number of key factors for the performance of EPBR plants. They include: • A very high degree of nitrogen removal can be achieved to approximately 2 mg/ L nitrate plus nitrite nitrogen even with high influent TKN concentrations of twice the strength of typical Australian domestic sewage. Lower concentrations would be achieved with more favourable influent BOD5 to TKN ratios more typical of domestic sewage.

• Very low effluent phosphorus concentrations of less than 0.2 mg/ L can be consistently achieved without chemical dosing. • Gravity thicken ing of EPBR waste activated sludge can be carried out without phosphorus release. • Operation of the aerobic digestion process to minimise nitrogen return to the main process can also result in minimal release of phosphorus eliminating the need for lime treatment of filtrate and enhancing the value of the biosolids for reuse - a major finding and benefit. • EPBR plants can be operated to achieve very good solids settling eliminating the need for bypass or permitting the use of much smaller secondary clarifiers. • EPBR plants can be operated to minimise the formation and release of the green house gas, nitrous oxide. • EPBR plants can be designed for "industry best practice" power consumption of less than 2.4 kWhr/kg 8OD5 including aerobic digestion. To realise these benefits, it is recommended that: • Provision be made for a de-aeration zone prior to the main anoxic zone. • Provision be made for a high dissolved oxygen post aeration zone. • Provision be made for accurate control of aeration for the main bioreactor and the aerobic digester. • The internal recirculation should be controllable to minimise dissolved oxygen carry over whilst achieving the necessary recirculation for low effluent nitrate concentrations. The Alliance Optimisation Period has been completed however, further investigations continue with the Wetalla Plant. As chemicals for nitrogen and phosphorus removal have been eliminated and power consumption is very low, the focus is on the minimisation of solids production and improvements in dewatering. These investigations are showing promise and, if successful, will further enhance the standing of the Wetalla AWTP as a highly efficient and low impact plant.

Acknowledgments The assistance and support of the Wetalla Alliance Management and team members is gratefully appreciated. The ongoing support of Toowoomba Regional Council and the Operations Staff of

Wetalla WRF in the subsequent optimisation and research has been generous and extremely supportive.

The Author

Peter Griffiths is a Principal Technologist with CH2M HI LL (Aust) Pty Ltd Queensland Office. He has worked on improvements to BNR plants for 25 years. Email: peter.griffiths@ch2m.com.au

References Ab usam , A. , Keesman, K.J ., Spanjers. H., van Straten, G., Meinema, K. 2002. Effect o f oxidation ditch horizontal velocity on the nitroge n remova l p rocess. European Wate r Management Online. Alinsafi, A., Adouani, N ., Seline, F., Lend ormia, T., Limousy, L., S ire, 0 . 2008 Nitrite effect on nitrous oxide emission from denitrifying activated sludg e. Process biochemistry 2008, vol. 43, no 6. Casey, T.G., Eka ma, G.A., Wentzel, M.C. a nd Marais, G.v.R. (1993) An hyp othesis for the causes and control of lo w F/M fil amentous organism bulking in nitrog en (N) and nutrient (N & P) removal activated sludge systems. Proc. of the IAWQ First Int. Cont. on M icroorganisms in Activated Sludge and Biofilm Processes, Paris. Clayton J .A., Ekama G.A., Wentzel M.C. and Marais G.v.R. 1991 Denitrification kinetics in b iological nitrogen and p hosphorus removal activated slud ge systems treating municipal waste waters; Wat. Sci. Tech. 23. Foley, J . 2009. Life cycle assessment of wastew ater treatment systems. Ph D Defence. University of Queensland. Griffiths, P ., Tonkovic, Z. 1990. Optimisation of flow configurations for biological removal of nitrogen and p hosphorus. AWA IAWPRC, First Australian Conference on Biological Nutrient Removal, Bendigo, Victoria. Griffiths, P. , 1994 Modification to IAWPRC Task Group General Activated Sludge Model. Water Research Vol 28 No 3. Griffiths, P., Stratton, H. M., Brooks, P., Seviour, R.J., 1997. Problem organisms in activated slud ge-causes and cures. AWWA 17th Federal Convention, Melb ourne, Victoria. Griffiths, P., Daigger, G., 2009. Leading Edge Nutrient Removal-design and operating development und er string ent Australian conditions. WEFTEC 2009 Johnson, B .R., Narayanan, 8. , Baur, R. , Menge lkoch, M., 2006. High-level b iological phosphorus removal fai lure and recovery. WEFTEC 200 6. Stratton, H.M., Brooks, P.R. and Seviour, R.J. (1998). Activated sludge foaming: What ca uses hydrophob icity and can it be manipulated to control foaming? Water Science and Technology, 37(4-5) 503-509. WRC; 19 84 Theory, design and operation of biological nutrient removal activat ed sludge processes; Water Research Commission; P.O Box 824, Pretor ia 0001, South Africa.

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INNOVATIVE DECENTRALISED SEWERAGE SOLUTION Yarra Valley Water (YVW) has recently awarded lnnoflow Australia/Orenco Systems Inc the contract to supply interceptor tanks and effluent filtration/ pump packages for the first known community STEP (Septic Tank Effluent Pumped) wastewater collection system in Australia. The system will be installed at Kinglake West - Kinglake was one of the five Victorian towns severely damaged by bushfires early in 2009. YVW with the support of the Victorian Water Trust, has developed an all encompassing and innovative sewerage solution (which has been in planning since 2006) that wi ll deliver environmental benefits. YVW and lnnoflow will work closely with Murrindindi Shire Council, with GHD which has been awarded the effluent sewer design contract, and with Schultz Plumbing which has been awarded the installation contract.

Water Business aims to keep readers alert to business news and new product releases within the water sector. Media releases should be emailed to Brian Rault at brian.rault@halledit.com.au or Tel (03) 8534 5014.

AWA wishes to advise readers that Water Business information is supplied by third part ies and as such, AWA is not responsible for the accuracy, or otherwise, of the information submitted.

topography in Kinglake West, adaptability is crucial to a successful project. The interchangeable nature of the effluent pumps along with t heir ability t o operate effectively over a wide range of system pressures makes design of STEP collection sewers significantly easier. Systems can also be designed with more confidence when the fibreglass tanks are used as a result of reduced potential for infiltration."

discussion from local residents. We made the decision to go with fibreglass in the end as the tanks are more lightweight and maneouvrable, and potentially more watertight." Chris Chivers of Schultz Plumbing commented that "Aft er having installed the first delivery of tanks we have found them quite easy to work with. I initially had reservations about the fibreglass tanks, but have since found them easier to work with than concrete. We have some site access issues at Kinglake and with the fibreglass tanks t hey are easily manoeuvred around with our machine and into situations that we would otherwise strugg le to get a crane truck in for the concrete tanks."

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NEW RDO METERS The new Thermo Scientific Orion Star RDOÂŽ series of optical dissolved oxygen meters now available through Thermo Fisher Scientific are designed to ensure the best accuracy with the least amount of maintenance.

The first fibreglass on-l ot intercept or tanks were installed mid-February 2010. Rita Narangala, the Manager - Backlog Planning for Yarra Valley Water said that "My view of the fibreglass tanks so far is that they have been very easy to move around the sites, many of which are small blocks with limited space and other building works taking place concurrently." "A side benefit is the distinctive appearance of the t anks which has certainly generated interest and

Ben Asquith, Senior Environmental Scientist, BMT WBM Pty Ltd (and a peer reviewer for the Kinglake West Sewerage Project) added that "Given the limitations to sewerage system design posed by

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102 APRIL 2010 water

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Water Journal April 2010  

Water Journal April 2010