Water Journal September - October 2000

SEPTEMBER/OCTOBER 2000

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Volume 27 No 5 September/October 2000 Journal of the Australian Water Association

Editorial Board F R Bishop, Chairman B N Andmon, P Draayers, W J D ulfer, G Finlayson, G A Ho lder, M Kirk, 13 Labza, M Muntisov, N Orr, P N adebamn, J D Parker, M Pascoe, A J Priestley, J l<.issman, F R o ddick, EA Swinton I ·,

CONTENTS From the Federal President ...... .. .. .... .. ............... .. .. ..................... ... ................ 2 From the Executive Director ... ..... ..... ...... ........ ......... .............. ........... .... .. ..... 4 MY

POINT

OF

VIEW

Water is a refereed jo urnal. This symbo l

indica tes that a paper h as bee n refereed .

Submissions

Don't Complain with your Mouth Full ..... .. ... .. ......... ... .... ......... .. ...... ..... :... .... . 8 S Mi!Js

Submissions should be made to E A (Bob) Swinton , Feawres Edito r (see below for d erails).

General Editor Peter Stirling PO l3ox 84, Hampton Vic 3 I 88 T el (03) 9530 8900 Fax (03) 9530 89 I I

Features Editor EA (Bob) Swinton 4 Pleasant View C res, Wheelers H ill Vic 3 150 T e l/ Fax (03) 9560 4752 Email: bswinron@bigpond.net.au

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CSIRO

URBAN

WATER

PROGRAM

The Urban Water Program .............. ........... ....... .. ....... .. ......... ..... .......... ..... ... ... 10 A Speers Life Cycle Costing of Urban Water Systems ....... .... ........... .. ..... ........ .. .. .... 12 S N T ucker, V G Mitc hell and L S Burn UVQ: A Water and Contaminant Balance Model ................ .. ..... ................ 14 V G Mitc he ll and S R. Gray TAWS for Assessing Alternative Water Systems .............. .......... ..... ........ 16 S Mah eepala The Scenario Manager ....... ........ .. ....... ..... ... ...... .... .... .. ... .. ... .... ........... .... ....... ... 17 M R eed, J Coleman and C Zoppou Peak Levelling in Urban Water Reticulation Systems ............................ 19 R. J Shipton Peak Load Management at WWTPS ...... .... .. ......... .. ........... .. ... ........ .. ........... .. 20 N Booker Economic Scale of Greywater Reuse Systems ............ .. ... .......... .. ... .......... 22 N Booker Septic Tank Replacement ..................... ... ...... ....... .. .... ........... ............... ........ .. 24 S Gray, N Booke r

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WASTEWATER

Water (ISSN 0310 - 0367)

Water Recycling ........... ..... ........... .... ...... ... ...... .... ........ ... .. .. .... ..... ... ..... ..... .... 26

is published in January, M arch , May, July, Se pte mbe r and N o v ember.

J Anderson

Australian Water Association Inc ArU3N 054 253 066

Federal President A llen Gale

Executive Director C hris Davis

AWA :s-=..:. ~

•

AUSTRALIAN WATER ASSOCIATION

Australian Water Asso ciation (AW A) assurnes no respo nsibility for opinions or statements of fa cts ex pressed by con tri b utors o r advertisers .

Editorials do no t necessaril y represent offic ial AW A po licy. Advertisements are included as an information service to readers and are reviewed b efore publicatio n to en sure relevance to the water en viro nment and objectives of A WA . All m aterial in Water is copyright and should not be re produced wholly o r in part with out the written perm issio n of the General Edito r.

The Willunga Basin Pipeline - Stage 1 ... ... ... ........... ........................ .. ....... 27

J G ransbu ry Wastewater Reuse: A Practical Viewpoint . .... .. .. .. ... .. .. .. . .. . ... .. . .. . .. . . .. ... .. . 32 A Murphy and J M urtagh From Problem to Profit: The North Adelaide Plains Irrigation Project ....... 37 J Kell y and D Steve ns Australia's Largest Water Re-Use Projects .................... .. ... .... .... ... .. ....... 42 B Ellis Guidelines for Wastewater Irrigation ..... ...... .... .. .. .. .. .... ... ...... ... ... .... .... .. .. . 43 R Stande n Managing Effluent Irrigation: The Sodification Threat .......................... 45 P Donlon and A Surapaneni Spuds and Flowers: The Barwon Water Green Industry Probe .. .. ... .. ... 49 C H owi e ENVIRONMENT ·, A Future for Melbourne's Platypus ........... ...... ......... .. ........ .. ........ .. ...... 51 V P ettigrove DEPARTMENTS

Subscriptions i,Va rer is sent to all A\VA members six rimes a year. It is also available via subscription.

Visit the Austrail, Wate As oc1at101 HOME PAGE and access news, calendars, bookshop and over 100 pages of Information at

Aquaphemera ... .. .. .. .. ..... .. .. ..... .. .. ....... .. .. .. .. ....... .. .. .. .. .. ..... .. .. .. .. .. ....... .. .. .. ..... .. .. .. . 2 International Report ............................... ....... .......... ........... ....... .. ......... ...... ...... 6 State Report ..... .. .. .. ... .. .... .. ....... .. ....... .. .. ....... .. .. .. .. .. ....... .. .. .. .. .. ..... .. .. .. .. ..... .. .. .... 9 Membership ..... ..... ...... ..... ..... .... ...... ... ...... .... ............. .... ......... .... ....................... 55 Meetings .... ........ ...... ................................... ....... .... ...... ... .............. ............ ... ..... 56 OUR COVER: L11yi11g tl,e A BS pipe e11 ro11te to tl,e N ort/1 Adelaide P/11i11s irr(',/11tio11 project. P/1010 co11rtesy < if E11r11pipe Pty Ltd.

FROM

THE

PRESIDENT

VIABLE WATER UTILITIES M y recent visit to the USA highlighted th e range o f i nstitutional arrangements for th e w ater industry and the significant steps taken in so1ne parts of Au stralia over the last decade to co nsolidate and update past arrangem ents. T he si tuati on in th e USA, with a pletho ra o f small w ater utiliti es, and with nervousness abo ut take o ver from private "giants", is not a good lo ng term model. H ow ever, we sti ll ha ve a way to go before we can consider to have reached a stable situation.

T he pa tchw ork of institutional arrangements across Australia has yielded a range o f different models fo r running water utiliti es. Given that W estern Au strali a, So uth Australia, the N orthern T erritory and th e AC T all have single agencies responsible fo r water services, th ey are very unitary in the ir designs. In other states, though, things vary a great deal. Victoria, w ith 19 urban utilities (all state owned corporations) is o n e extrem e, w hi le Qu een sland , with so me 125 different local governme nts is at the other. NSW, w ith three statutory corporatio ns and over 120 local autho rities is mixed, as is Tasmania , w ith several differe nt models in ope ration.

A common attribute o f the lo cal go vernm ent- based models is that th ere are numerous small utilities, many probably belo w a critica l mass to ope rate for o ptimum tec hni ca l a nd ec on o mi c outco mes. T he Vi ctorian situation, hardwon over several yea rs, has aggrega ted a previou s 400 or to tin y utilities into the current 19, all much more viable . This model is provin g to be successful , w ith authoriti es havin g stron ger fin ancial and reso urce bases to provide a be tte r service to customers whil e having co mpetition by comparison .

Local go vern m ent agenc ies, pe rhaps w ie lding more po li tical clout than the erstw hil e Victorian water utiliti es, tend to defend their autono m y and indep endence, a natural reaction , but o ne that n eeds to be considered carefull y in the light o f cu rrent alte rnatives.

Nati o nal co mpetition policy and wate r refo rm have see n p rov id ers ge ne rall y se p arate d fr om regulators . T h e local gove rnment response to th ose agendas has ma inly been to create a bu sin ess unit fo r water services, but to keep it firm ly under co ntrol o f the loca l council. T hat may en hance tra nsparency, but does not gua rantee improved effi ciency. Fo r small local government agencies, in particular, it is ha rd (perhaps impossible) to assemble th e skills and resources to deli ver water and coll ect wastew ater at competiti ve rates, and to match th e se rvice standards that are bec om ing the norm.

2

WATER SEPTEMBER/OCTOBER 2 000

Allen Gale

Loo king at th e Non Major U rban W ater Auth ority Performance R eport 1998- 1999 that we have j ust published, and WSAAfac ts 99, fro1n th e Water Services Associatio n , it is instru ctive to note that th e average cost o f w ater delivery per property, fo r the 21 largest utilities, was around $164, whil e the 67 smaller utiliti es reported in N M U had a m edian cost of $187, ie 14% higher (if averages were compared fo r both , the disparity w ould be eve n large r). Imagine ho w mu ch higher the costs w ill be fo r really small authorities, since the NMU report cove rs th e mid-size d pla ye rs, se rvi ng between 10,000 and 50,000 co nn ectio ns.

There are a few options fo r addressin g this situatio n . O ne already in use in Australia in three states is to conso lidate water se rvices for a regio n and to establish a j oincly ow ned busin ess co serve multiple communities.

Another is to franchise out the op erations, so a pri va te player could deli ver services to multiple communities in a given regio n .

B ega Shire C ouncil o n the south coast of N SW has broken the ice in that respect and is, at the time of w ritin g, searchin g for a franchisee . The most drastic option would be fo r all small co mmunities in a region to sell off their e ntire water op eratio ns co the pri vate seccor. That is unlikely co be countenanced in Australi a, thanks to w idespread con cern over the loss of ownership of assets..

Th e opti on th at suits best will have co be developed in th e context of local co nditions and policies, as well as neighbouring circumstances. T here would probably be a different model fo r eac h situatio n, but it is impo rtant fo r the stakeholde rs to start chinkin g about th ese issues now. A plan imple me nted voluntarily and w ith du e co nsiderati on is going be lot more ame nable (an d probably more successful) than o ne imposed la ter on, in political circumstances.

Allen Gale

Aquaphemera O ve r rece nt iss u es Aqua ph e m e ra h as fo c u se d on Australian w ate r u se, a topi c bedevilled by a paucity of data the last compreh ensive national review was for the wate r yea r 1983/84 . The searc h fo r a n ew t h e m e mu se, h o w e v e r , b e p ostpon ed in order to report on Water account fo r Australia 1993/4 to 1996/97, published by the Australian Burea u of Statistics 111 M ay 2000.

T he major contribution is to present annu al w ate r use statistics by sector. The key finding to em erge is that irrigated wa ter for pasture has risen to nea rly 8,000 GL p er year, approximately 40% of total national wa ter use. In comparison, all ocher irriga ted uses total close to 6,000 GL. If these fi gures are co mpared to those for 1983/84, total national w ater use has increased by 50%, chat for agric ulture by a similar am ount, w hile pasture use has risen by a staggering 70%. In contrast natio nal h o usehold use has, ove r t h e thirteen y ears, inc reased by only 2%. In te rms of quantity, the additional an nual applica tion of irrigatio n water to pasture is do uble t hat used by the household seccor in a year.

The Bureau is to be congratulated on publishing data o n this long neglected topi c. However, the presentation of the data by State is to be lamented , the reason given is 'that spatially disaggregate d data [ic. by catchment] w as unavailable' . If nothing else, the last thirteen years have w itnessed the need fo r planning by ca tch111ent.

A thrust o f the study is to pr es ent a n 'e nvironme ntal accounting framework ' although th e de tailed data are restricted to Victoria. E ven this is far from satisfactory as th e 'stock tables' use id e ntica l a nnu al precipitation, evapo cranspiratio n and runoff data fo r all fo ur years!

I am cold that this first edition is a trial, and that the 2000-2001 editio n aims to tackle estimates at a more regionalised level.

Let us hope that the N ational Water Audit, to be presented later this year by LWR.RDC , using so me of the ABS statistics, is of m ore value . As rep orted w ith tedious regularity in this column, I fail to compreh end how th e nation can claim to have a w ater policy w hen it is not known w ho uses w hat, where or for w hat purpose!

Dingle Smith

STATE

REPORT

MINISTER ADDRESSES AWA The H on She rryl Garbutt MP , Ministe r fo r En v iro nment and C onservation was Guest Speaker at the AGM - Dinner of the Victorian Branch of the Australian Water Association where she addressed o ver 400 members and guests, following an introdu ction by Mike Muntisov, Branch President, who comme nted on the presence of some 19 CEOs of major water authorities at th e dinner. Minister Garbu tt gave a succi nct and positive message on the direction of the State Government. The succession of dry years in Australia, now in the 4th year, w ith no sign of biblical floods to reverse the situation and reservo irs at their lo west ever. She noted that getting M elbo urne consumers to save water is more difficult than Essendon losi ng the AFL Premiership, p erhaps just a touch of bias here.

Sherryl Garbutt went o n to say that t he Government is committ ed to managing water to ach ieve sustainable use of water and good water quality.

Action has been taken to implement COAG reforms, encompassin g bulk entitlem ents, environmental flows, farm

dams and groundwater management.

With 100 towns on water restrictions already, and the likelihood of restrictions spreading to M elbourne and other towns, there is a need to lift public awareness on water and its conservation. T here is a need to attribute the real va lu e of water and use it more efficiently. The aJlocation of$ 30mill ion over 3 years is to increase efficiency in the use of water and provide for economic growth and environmental improvements w hich is part of the Bracks Government commitment.

The second Government commitment is on Drinking Water Q uality and to this e nd D epa rtment of Human Services and D epartment of Natural R esources and E nvi ro nment, under th e ir res p ec ti ve Mini st e rs, M ess rs Thwaites and Garbutt have launched a consulta tive framework to ensure that drinking water is safely managed. The Minister hi ghlighted the need for reform and the community sensitivity to water quality, w hich necessitates the provision of drin king water standards fo r large service providers with some flexibility for small er com munities. In short the

provision of a single State wide regulatory system for dri nking wate r in w hich the risks wou ld be managed.

The Minister took the opportu nity at the dinner to deliver the inaugural launch of the Consultation Paper "A New Regulatory Framework for Drinking Water Quality in Victoria". The Minister invited responses from AWA members who had specialist kn owledge of drinking water quality and risk management.

T he closing date for comments on the document was 13 October 2000, after wh ich submissions would be analysed and thence followed by workshops fo r sta keholders. It was planned that proposals would be finalised and introduced to Parliament by March 2001.

• Writte 11 Comme11ts to Co 11sulta tio11 Paper close Friday 13 O ctober 2000 should be directed to: Drink ing Water Q u ali t y R eg ul atory Fra m e w ork Response to Co n su l tatio n P ap er: Direc tor, Water Sector Serl'ices, D ep artm ent of Nat ural R esources and E ,w ironmw t. Telephon e: 03 94 12 4020 Facsimile: 03 94 12 4360. Email: water.services@nre.vie.gov.au

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CSIRO

URBAN

WATER

PROGRAM

THE URBAN WATER PROGRAM A Speers In 1998 CSIR.O e mbarked on an ambitio us research progra m directed to improving the sustainability of Australia's urban water systems. T his ini tiative was strongly supported by th e Australian water industry, through the Water Services Association of Australia, the Australian Water Association and the Cou ncil of Austra li a n Governments (CO AG ).

Appreciation must also go to CS IRO's late C EO, Dr Malcolm MacIntosh, fo r his vision in supporting programs such as this, through a Special Projects Fund .

Known as the U rban Water Program (UWP), th e initiative has rece ntl y concluded its feasibility stage by ide ntifyin g the most promisin g opportuniti es to improve system performance and is now proceeding to the second phase ..

A fu ll description of the structure of the Urban Water Program appeared in the Septe m ber 1999 editio n of Water. T he fo llowing fea ture ou tlines the key research direc tio ns pu rsue d, and ve ry bri efl y summarises som e of the results

Essentially, VWP researchers from the CS IR O Di v isions of Buildin g, Construction and Engineering, Molecular Science, and Land and W ater have sought to identify oppo rtu niti es to im prove system sustainabili ty by analysing existing urban water, wastewater and storm water system s, the flow of water contaminan ts through them and the life cycle costs of these systems. This enabled the dri vers of system cost and design to be identifi ed and the impact of changes to system operation and configuration to be quantified.

"77w o~jea of l!fe cycle costi11,~ is to ide111{fy the 111osr eco110111ic overall choice. l11irinl wsts i11c/11de nit i1111es1111e11t costs directly relnred ro tire project, such as cosrs of pla1111i11g, desig11, co11stn1crio11 a11d i1wnllnrio11, fees n11d clin1gcs, m1df,11n11ci11g costs n11d_f,11111·e wsrs. F11111rc costs co111prise opernri11,~, 111ni111e11n11ce, re/1nbilirn1io11, de1110/i1io11 l rr111011nl costs, m,d property n11d cnpirn/ gni11s taxes". (Glossary of Australian 13uilding T erms) Identifying those factors havin g the greatest impact on capital and operating costs over time enables them to be amelio-

rated or en hanced. Accordingly, an extensive database has been created in the VWP through CS! RO 's own research, with the contribution from participating water companies, of lifccycle costs associated with all assets of water and wastewater systems from the off-take of water supply th rough to th e di sposal poi n t after wastewater treatm ent.

W ith regard to water and contaminant flows, patterns of water co nsumption and the flow of contaminants within systems were identified. Detailed analysis was co nducted inro patterns of domestic water consumption , using a select group of 720 households, and trends in water consumption in various oth er sectors (eg commercial industrial , parks and gardens etc) fro m cities throughout the counny.

An ex te nsive li terature review of contaminant loadin gs identi fied loads and load reductions at various points such as the hom e and in wetlands, treatment faci lities, etc. Contamin ant flow data was combined with water flow data in a

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10

WATER SEPTEMBER/OCTOBER 2000

ZEOLITE

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comprehensive water and contaminant balance model (UVQ Urban Yolume and Qua lity) . Th is model allowed co mpari ons to be made of the impacts o n flow~ of different ~y~tem configurations and under different demand and other scenarios.

For example the separate treatment of blackwater in lowdensity fringe areas was compared to existing septic syste ms and shown to produce a signifi cant reduction in nutrient discharge at on ly 40% of the cost of conventional systems.

Effort was directed to develo ping a method through which externaliti es co uld be identified and quantified and suc h a trial should soon proceed.

H aving characterised the existing system, effort was also directed to ide ntifyin g and quantifying the performan ce characteristics of alternative technologies. Treatment tec hnologies have been combined in a database as 'process trains' rather than individual technologies and data collated on pe rformance c haracteristics, cost and level of developm ent. Pipe line and pumping data includes information o n pipe mate rials and performance, cost , laying options and other focto rs.

This data was used in a process of 'sce nario' analysis whereby diffe rent system configurations were developed based on knowledge of system characteristics and future performance requirem en ts an d possibilities. T his alJowed comparison w ith co nventional system s.

Alternative water system con fig urations were not developed in isolation. From the outset it was co nside red important that com munity attitudes and acceptance be co nsidered. To this end, trends in community attitudes to alternatives were reviewed and en hanced through new research undertaken using the 720 ho usehold contro l group referred to earl ie r. The results of this anal ysis were used to shape the scenarios analysed in the UWP. For example, it was found, possibly unsurprisingly, that only I I% of people would suppo rt direct potable re use where treated e fflu ent was the water source. H owever 51% support reuse water fo r laund1y use, with a fu rther 20% feeling ambivalent about such an application . T his fi ndi ng suggests that non-potable reuse can be quite w idely applied, particularly as laundry use was fo u nd to be the second most significant in-house use of water.

In addition to social research, potential climate change scenarios were developed, to provide a broad pictu re, when combined w ith water use trends, co mmunity attitudes, and drivers of system design , of the future requireme nts that w ill need to be catered fo r.

The result of th e scenario analysis and on the models developed to man ipulate the data coll ected in the program appear in the brief sum m aries reported in this issue. M ost impo rtantly, these included TA WS (Iool for .6.ssessing W ater $.ystcms) alJowi ng cost comparison o n a Lifccycle Cost Basis of alternati ve systems and optim.isation of syste ms , and UVQ, m entioned earlier.

The result of the feas ibility stage of the UWP is that significant opportun ities wou ld appear to be available to increase system sustainability and reduce costs. These will be researched fu rther in fu ture. Key research areas w ill include: peak flow and pressure management; lifecycle analysis; externaliti es; low cost sewerage systems and their impacts and cusro m er preferences fo r leve ls of service. Impo rtantly, opportunities are being discussed to establish a large-scale demonstration site at w hich th e concepts can be implem ented.

Finally, thanks are offered tO AW A, WSAA and representatives of water compan ies for their contribution to the feasi bi lity stage ofth e UWP. Andrew Speers is the D irect0 r of the UW P . Ema il : andrew.speers@ dbce .csiro .au WATER S EPTEM BER/OCTOBE R 2000

11

CS IR 0

URBAN

WATER

PROGRAM

Life Cycle Costing of Urban Water Systems S N Tucker, V G Mitchell and L S Burn, CSIRO Building, Construction and Engineering Introduction

especially when connecting smaller systems that currently utilise septic Water, wastewater and stormwatanks. Fu rther work will aim at ter infrastructure has been traditionidentifying areas of m ost potential for ally costed from either a capital or savm gs operating cost point of view. The The most important action to be calculation of the full costs of the undertaken as soon as possible is the infras tructure (excluding externaliacquisition of an extensive database ties) associated with the provision of 1000 2000 3000 4000 5000 6000 7000 of all establishment, operating and water services over the full life cycle Capacity (megalltres) maintenance and replacement costs provides a fa irer basis fo r the comparison of traditional and alter- Figure 1. Relationship between annual operation to enable the cost functions to be determ ined with more confidence. A native approaches to water supply and mainte nance cost s and storage capacity of structure for collecting and collating and disposa l. Life cycle costing dams and reservoirs details of an urban water system will (L CC) involves combi nin g th e are as simple and generic as practically be designed and implemented. Essentially estimated capital, maintenance, operatpossible for the various items of the urba n this requires water authorities to collect ing, and replacement costs over the water system. For example, it would be wh ole life of an infrastructure faci lity into very desirable to have one functio n for all data in an appropriately disaggregated a single value, which takes into account pipes but in practice there is a comm on form instead of the traditional accounting expenditure occurring at different stages form of formula but with different coeffi- methods where breakdowns of costs into in the life of the in frastru cture. cients depen ding on pipe type. A typical infrastruc ture items are rarely recorded.

A full LCC model includes the costs An extensive review has found that cost function is shown in Figure 1. for of all impact5, both directly and in directly there is little published literature that reservoirs as a functio n of capacity . controllable by the water authorities, i.e. docu ments the application of LCC to the the coverage of the costs sho uld be total urban water cycle. Single compo- Life cycle cost modeling nents of infrastructure services in water A life cycle methodology for deter- extended to externalities (those impacts resu lting from water systems implem ensupply, wastewater, and stormwate r mining life cycle costs of urban water, tatio n that are not in clu ded in the services have been considered in isolation. wastewater and stormwater infrastructure au thorities' responsibilities or budgets).

We have d eveloped a life cycle has been developed and implemented as T he impact of technology and system m ethodology for assessment of urban part of a T ool for Assessing Water change and its effect on the level of water systems. T he methodology has Systems (TAWS) at the component level been applied to five classes of potable of these system s, to determine the fu ll service provided needs to be assessed. water assets: storage, transport, pumping, costs associated with the provision of T his is especially tru e in ligh t of the treatment and disposal. The life cycle costs urban water services over the required arbitrary methods of defining customer service contracts in Australia. T hese associated with each of these classes of assessment period. impacts can best be assessed utilising LCC asset were defined in three categories: The model has been structured to establishment, operation an d replacement enable other characteristics such as green- concepts, bu t in addition, incorporating the concepts of costs associated with risk costs. Each category was further subho use gas emissions, and embodied and (externalities). T his is necessary as water divided into several sub-categories (e.g. ope ratin g energy calcu lati o ns to be capital, installation, m aintenance, staff etc implemented over the w hole life of authorities become m ore focusse d on the as appropriate fo r the category) to enable infrastructure when need and resources cost effectiveness of th eir systems and explicit cost funct ions to be defined. allows selection of the highest quality allow. T he emission of G reenhouse gases, system at the lowest cost particularly CO , is a significan t measure 2 Cost Functions Another critical area is asset m anageof the impact on the environment of the P rovision of data for LCC models is construction and operation of an urban ment especially in the area of pipelines. often an enormous task. Urban water water system over its life cycle and attenAsset management, requires considerasystem models are no exception , with a tion needs to be given to the abatement tion of a large n umber of factors such as hu ge data load required fo r estim ating of the emission of CO 2 , especially fro m condition monitoring, probability and sufficiently accurate tota l costs, to enable wastewater treatment plants consequence of p ipe failure, the correct comparison of alternatives. se lection of pipe re h ab ili ta ti o n or Cost fu nctions are the most desirable Application and future replacem ent techniqu es and the developdevelopment meth od for providing this cost informament of planning models to allow correct tion. The establishment costs and operaCost functions have been utilised in decisions and timing of asset replacem ent tion and maintenance costs of the item of the planning model TAWS to allow or rehabilitation to occur. C urrently infrastructure are defined as mathematical optimisation and planning cost com par- decisions made on pipe replacement are functio ns of one or m ore variables relatisons between different scenarios fo r very subj ective and are based upon the ing to the p hysical size, nature, throughurban water system,. indicating that nu mber of failures that occur in the pipe put, cap acity or type of the infrastructure rather than on economic considerations. potential savings of up to 65% may be item. Efficiency of model.ling and data obtained by innovation in the installation In each of these processes LCC plays a entry requires as few cost functions as of U rba n P ota ble Wate r systems . critical part as these decisions need to be p ossible.

P reliminary analysis of sewer system s has made based on to tal life cycle cost impliT he cost functions so fa r developed cations. indicated that potential savings exist,

12

60

WATER SEPTEMBER/ OCTOBER 20 00

CS IR 0

URBAN

WATER

PROGRAM

UVQ: A Water and Contaminant Balance Model V G Mitchell, S R Gray, Building Construction and Engineering: Molecular Science Introduction A conceptual dail y urban water and co ntaminant balance m odel called UVQ (Urban Volume and Q ua]j ty represents wa ter and co ntaminant fl ows thro ugh the existing urban wa ter, was tewater and sto rmwater sys tem s, fr om so urce to disch arge p o int. T h e o u tput assists sce n ario an alys is b y assess i n g th e adequacy of urban wa ter resources fo r current and future water demands and provides data fo r assessing the lo ng-term enviro nmental impacts.

T h e m o d ellin g appro ac h is th e integration of the potabl e supply-was tewater disposal network and the rainfallrun off network into a single fra mework.

T his affo rds a hobstic view of the urban w ater system and offers the opportuni ty to investigate the effect of wa ter reuse .

Water Balance Component W o rk at t h e C R C C atc h m e n t H yd ro logy has developed a mo del, Aquacycle (Mitchell , 2000) which rep resents indoor and outdoor wa ter supply, st o rm wa t e r r u n - off, was t ewa t e r discharge and wate r reuse.

T o meet th e requirements of this study the fo ll owing new wa ter flow paths we re added and a contanun ant balance linked .

• A pathway between the gro undwa ter store and the previous soil store, r presenting garden irrigation using bore wa ter.

• Spoo n drai ns and infiltratio n basins where they are used to infiltrate runoff • On-site disposal units with leach fi elds, whi ch service a small propo rti o n of urban areas • Exfi ltration and o ve rflows from the ·was tewa ter system , th o ugh comparatively small fl ows, are important fo r the transportatio n of contanunants w ithin the urban wa ter system .

Contaminant Balance Component T he mapping of co ntaminants in the model coincides with the mapping for the wa ter balance, thus directly representing the way in which alterations in the w ater flows affect the movem ent and distribution of co ntanunants. It was also necessary because in m ost instances the contaminant loa d is expressed as an event mean co ncentratio n, and thus requires a flow of water fo r calculati on of the loa d.

T his approac h is appropriate fo r the wa ter supply system , fo r whi ch co ntaminant data is readi ly available and temporal variatio ns in quality are small.

14

Variabi]jty in the contamin ant loads in sto rmwa ter arises from land use and so urce c harac teristics. Fo r in stance, contamin ant profiles fo r ro of ru noff were charac terised acco rding to the reside nti al, industrial and conune rcial land uses, w ith a sub-charac terisa tio n into inert and galva nised roo f types. Fo r ferti liser applica ti on to gardens, sub-characterisa tion acco rding to housing density fo r res idential clusters was used . T his allows a coarse d scriptio n of the site to be incorp orated in to th e con taminant m odel. T his approac h reli es heavily o n ap propriate conta nunant proftles fo r each stream , and a considerable database of contanu nant pro fi les based on repo rted literature values was coll ected. T he contaminant loads fo r in- ho use wa ter uses w ere specifi ed as a load per person per day, allowing fo r va riations in wa ter quali ty ca used by demand manage ment techn iq ues and recycling of wa ter.

Spatial Scale UVQ uses several spatial scales to represent the components of an urban area . Three nested spatial scales have been selected, unit block, cluster, and estate . A unit block represents a sin gle property that can contain bu ilding(s), paved areas, and pervio us areas such as ga rden . A cluster i comp rised of a numb r of un it blocks as well as roads and pub]jc open space, representing a neighborhood o r local area . An estate is co mprised of a number of clusters that may or may no t have the sa me land use .

Treatments Wa ter q uali ty in fl ow strea ms is changed by treatment of the wa ter. T he UVQ model ca n use eith er of two optio ns fo r calculatio n of slud ge or residual co ntaminant; both are simple and data is readily available: • W ater quality in and o ut is specifi ed • T reatment efficiency is specified .

While igno ring the complexity of th e trea tment processes , tl1ey allow the user to make a coa rse assessm ent of contanunant bui ld up and identify th e areas w here furt her investi ga tio n of a wa ter sys tem co nfi guratio n is req ui red o r id entify w hat level of trea tm ent is required to ac hi eve a certain enviro nm ental outcome. Further enhancements to the m odel could allow mo re co mplex treatments to be m odell ed.

Water Supply, Disposal, and Reuse

WATER SEPTEMBER/ OCTOBER 2 000

in additio n to traditio nal reticulated

supply, alternati ve so urces as listed below were assigned potential uses, rangin g fro m kitc hen to ga rd en irri gati on .

• R eticulation • Ra in tank • Sub-surface greywater irrigatio n • O nsite trea ted was tewa ter • Gro und water bo re • Aq uifer sto rage and recovety • C luster stormwa ter store • Cluster was tewater store • Catchme nt stormwater store • Ca tchment wastewa ter store T he m etho d of descri bin g co ntaminant loads from sources also all ows di ffere nt systems to be analysed, as flows fro m va rio us sources can be combined, di verted or trea ted separately.

Outcomes T he U rban W ater Program has used UVQ to compare a conventio nal wa ter system and a system in which gre)'\¥ater and sto rmwa ter are used fo r non-po table applicatio ns (Mitchell et al, 2000) . UVQ has alJowed the availabi]jty of water fo r recycling to be assessed as well as the destination of contaminant loads to be co n sid e re d 111 th e co mp an so n.

Contanu nant loads at the discharge points within the system , such as ho usehold ga rdens or sewage treatment plant efilu ents, were estimated, enabling the identifi catio n of possibl e po ints of conta nunant build up . T he number of days that the concentratio n of to tal dissolved soli ds in th e recycle strea ms exceeds the level fo r unrest ricted irrigatio n use was also tracked, allowing th e suitability of recycle wa te r fo r sp ec ifi c p urp oses to be mo nito red. T he program pernu tted rapid analysis of alternative water supply and disposal systems to occur and incorp orates site specific charac teristics. Furth er use of UVQ will elucida te the strengths and deficiencies of th e model, highlighting the way in w hich the model can be further developed to extend its usefulness and capabi]j ties .

References M itchell V G (2000) Aquacycle User Man ual, CRC for Catchment H ycjrology, Monash University, Australia.

M itc h ell VG , Gray, SR. and Fa rl ey, T. , " Accou nting for Wa ter and Contam inants in Urban Areas", Proc. Xth World W ater Congress, Melbourne, l 1-1 7 March, 2000 Intern ationa l Water R esources Associatio n (IW R A), Assoc iation Inte rn ationa le des R.esources en Eau (AIRE) and AIR..E H .

CS IR 0

URBAN

WATER

PROGRAM

TAWS for Assessing Alternative Water Systems S Maheepala, CSIRO Building, Construction & Engineering A Decision Support System

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Pomp

Tank

Demandl

demonstrated. Howeve r, offsetting these savings is the cost of on-site storage tanks, which was not included in the ana.lysis.

TA WS (Iool for (A) (B) Assessing Water Systems) was develope d to an alyse alternatives to traditional Scenario 2 m ethods of providing urban The traditional materials water services . An ea rlier such as steel and rei n forced CS IRO model that was co n cre t e were compared Elkmbrook app lied in the Spe n ce r Henley with PN6.3 polyethylen e Brook Region of Sou th Australia pipes for reticu lation m ains h as b een e nhan ce d and s uppl y ing water w ith i n applied to a study area in clusters and 300 mm PN16 ~ 7 Mlddle Perth.

Ul Sw..in polyethylene fo r the distriThe T AWS model uses a bu tion ma ins, but with tradimod e lli ng fra mew or k , tional pipe mate ria ls fo r w h ic h integ r ates water larger sizes because th ere are su pply, wastewa t er an d curren tl y no cost data availstormwater se rvi ces into a able for larger size polythene single model. At the present Figure 1 . A schematic diagram of the water supply system in pipes. time , only the water supp ly the study area: (A) logical network and (B) physical network The capital costs, includcomponent of th e three ing laying, we re reduced to infrastructure needed, subj ect to water infrastructure networks is included in 95%, and operation and maintenance qua lity, hydrol ogic an d hydrau li c the integrated modellin g framework. costs reduced to 49%. H owever, beca use constraints.

The water supply system is represented the amortisation of capital costs was by a logical network, which defin es m ore significant the overall savings are Scenario Analysis conceptual flow paths, and a p hysical only abou t 8%.

The TAWS model was applied to a n etwork, w hi ch defin es the actual physidevelopment area of 422 km 2 in no rth cal paths that th e water can travel Conclusions east of Perth, whe re population was between nodes of the logical network .

Whil e the pre limina ry modelling This provides a flexible method for expected to in crease from 40,000 to results are site specific and subject to 100,000 by 2020. lt was assumed that specifying numerous ways of providing various assumptions and the quality of the stu dy area was a greenfield. Figure 1 water and assessing alternative water data used, the cu rrent analysi s has shows main localiti es in the study area systems in terms of in fras tructure costs . demonstrated potential cost savings in and the logical and physical water supply The TAWS model can be used in transpo rt costs that can be obtained by netwo rks in clu ded in the TA W S model. two modes. In the 'what-if mode, the levelli ng of peak water demand and Some scenari os analysed u sing the model analyses a given configuratio n to changing of materials used fo r pipes . Th e TAWS m odel were: determine supply reliability, simulated r es ults have d emonstrated that the Scenario 1. Levelling of pea ks on water and p eak flows in th e transport system, TA WS model 1s useful in exploring supply transport costs an d sizes and life cycle costs of infrasalt e rnativ es t o th e tra ditional tru cture items. In th e optimisa tion Scena rio 2. Cost implica tions of adoption approach es .. mode, a stochastic o pti misation of polyethylene pipes over conven tional techniq u e simulated annea ling Further reading materials augmented with heuristic ru les - is used Maheepala S, and Gibert J (1997) Opti111isa1io11Scenario 1 to searc h for a configuration that based 111odel for i11t(~1¡ated 1/Jater rcso11rce minimises the total life cycle cost of Figure 2 illustrates the impact of plm111illg, P roceedi ngs of the 24th H ydrology and Water R.esources Symposium, reducing peak demand from Auckland, New Zealand, 24- 27 November, 243 litres/h ousehold pe r lfr4)3CI of peak levelling on water supply transport cost (for a P ublished by Institu ti on of Engineers, hour down to 95 litres/ greenfield development in Perth NEC) Australia, pp. 456- 461. ho usehold per hour. This Maheepala S, Gibert J , and van dcr Wei 13 preliminary analysis su ggests (1999) To111ards cos1-~(fecti11e a/id s11stai11able that p ea k leve llin g may water reso11rce devclop111wt ;,, tlie Spe11cer Resim1 result in savings of the order qf S0111/i A11stralia, Proceedings of th e Water 99 Jo int Congress, Brisbane, Australia, 6-8 of 34% in the transport cost July, Published by Institution of Engineers, of water.

Australia, pp. 1198 1203. fm. l - ~---,---,--..--~-,----.--,---,- - - i l f data had been available 95 105 115 125 135 145 155 165 175 185 195 205 215 225 235 245 Maheepala S, and Zoppou C (2000) Derisio11 to calculate operation cost Peak Demand in VhMlr S11pport Syste111 for Assessi11g /11te.~rated Urba11 using both pipe length and Wat er Syste111s, Proceedi ngs of the Xth Figure 2. Cost savings offered by peak levelling in diameter, furth er cost World Water Congress, Melbourne, 12- 17 the water supply system savings would have been March, 2000.

~

16

WATER SEPTEMBER/ OCTOBER 2000

URBAN

CS IR 0

WATER

PROGRAM

The Scenario Manager M Reed, J Coleman and C Zoppou, CSIRO Land and Water, Canberra Introduction

• recove ry of on-site runoff in soil stores.

• contaminant build up.

• justify e n vironme ntal benefits of expens ive sewage treatmen t.

Effective evaluation tools arc essential for the analysis of emerging urban water tech n ologics and re-use options. The "Scenario Manager" has been designed to enable the evaluation of integrated urban wa ter systems, comprisin g water supply, waste and stormwater treatment and disposal infrastructure. The major advantage of the integrated approach is that it enab les assessment of inte rac tion s between these strea ms.

The Scenario Manager provides the use r- interfa ce to an interactive modelling framework that enables the effic ient exam ination of alternative scenarios such as: • diffe r en t waste water treatment processes, altered pipe pressure class and materials used in transport systems and different peak 0ow factors used in the design of infrastructure.

• increased or decreased demands from ri sin g or fallin g population.

• c hanges in regulatory requireme nts.

• recycling and reuse of grey water in the home.

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Scenario Designer

Modelling Framework The major com pon ents of the interactive modelling framework are shown in Figure I. Curren tly, it includes the (i)

sce11ario 111a11ager, (ii) sce11ario desig11er, {iii) sce11ario reporter, (i11) 110/11111e a11d q11ality model a11d (11) opti111isatio11 111odel.

Two models, described later in this feature, have been in corporated in the p r e liminary development of the modelling framework: The UVQ model and the TA WS mode l, w hich has an optim isation mode.

The Scenario Manager Interface

There are nu merous parameters and options available in these mode ls th at could be modified by the user. A sophisticated interface is provided for altering these parameters and options an d to manipulate the huge amounts of data required by the models with relative ease.

The Scenario Manager consists of a user-

u

Scenario Manager Scenario Reporter

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Optimisation Model - - - - - - - - '

Figure 1. Urban water system modelling

framework fri end ly interface w hich; (i) contro ls access to the models, (ii) enables the user to specify an infrastructure using the Scena ri o Designer, (iii) allows fo r the efficient creation of input da ta fo r the models, (iv) va lidates data and (v) facilitates comparison between scenarios using the Scenario R eporter.

Scenario Designer

The Scenario Designer enables the user to select and modify the attributes of objects. These objects can reside in one of five spatial scales used to represent the urban water system . A regio11 represents a

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study area. Within a region there are a number of estates that consum e water and p rodu ce w ate r o f various q ua lities.

Groups of estates are used to represent a collection of residential, industrial and agricultural areas.

An individual area withi n an estate is referred to as a c/11ster.

A cluster can o nly contain buildings of the same typ e, known as 1111il blocks, or represen t an industrial area or an agricultural area that consumes water of a particular quality. Attributes of water consu ming appliances wi thin a building on a unit block can be specified at th e i11door level.

The Scenario D esigne r can access attribu tes of obj ects from the estate to the indoor level. A scenario will include; (i) time series of climatic data (ii) the urban wa te r infrastructure (iii) the attributes of estates, cluste rs, garde ns and houses. The scenario designe r consists of four components; (i) 11ett11ork des(e11er, (ii) estate desig11er, (iii) duster designer and (i11) !to11se des(e11er.

An example of the network designer interface is shown in Figure 2. Tools are available fo r designin g the urban water supply and disposal network and to specify their attributes, such as pipe sizes and length .

T he interface of the house design e r is shown in Figure 3 . It allows the user to change the attributes of objects, such as

URBAN

WATER

PROGRAM

the type of water consuming appliances within th e hom e The Scenario Reporter

The design fo r the Scenario R eporter allo ws the user to compare scenarios both graphically and using summary statistics. It is not yet full y impleme nted.

Conclusion

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The fl ex ibilit y o f th e Scenario Manager allows other models to be readily included in Figure 2 . Urban water system specified using the modell ing framework. T he th e Network Designer types of mo dels that are thought to be importa nt in scenario a nal ys is include : modelling of exte rnali ties, QR--..:•tri. ,11 Q\11.....,._r....,.rflClll, models to estimate the cos t of infrast ru c ture lll:l!'l'l!i!I ,.."" ., c:=J : c::::J] , failure, a nd m o d e ls l•"""*'"'·B ,ffl.,..,,...,., ~ , ...1,,....." ;-.

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The Scenario Manager Gifdlrt.trfNl, q • ) ~ u,c.ld:po,ied ~ has been successfully used ~ dti,epoord . . ·, Q L'"4l(tl f ~ Q S~tc to a nalyse a ran ge of sce na rios for al te rn ate water suppl y strategies, Figure 3 . Attributes of a house that can be specifi ed based o n a case study area. using the House Designer

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Flexible Delivery Mode: • Distance Learning • Part-time

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The National Centre for Groundwater Management (NCGM) at t he University of Technology, Sydney is recognised by the Federal Government through the Land and Water Resources Research and Development Corporation as a National Centre for Training, Research and Consultancy in Groundwater and Environmental Applications.

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Study areas include: • Groundwater Contaminant Transport Modelling • Quality and Quantity Optimisation Strategies for Water Resource Development • Waste Management and Groundwater • Contaminated Land Evaluation and Rehabilitation • Bore Fouling and Maintenance • Practical Areas of Hydrogeology including Geophysics, Hydrogeochemistry and Microbiology aspects • Land and Groundwater Salinity For Applications and Information contact: Professor Michael J Knight, Director National Centre for Groundwater Management University of Technology, Sydney, PO Box 123 BROADWAY NSW 2007 AUSTRALIA Phone: (02) 9514 1984 Fax: (02) 9514 1985 E-mail: groundwater.management@uts.edu.au Website: http://groundwater.ncgm.uts.edu.au/ncgm/

Short course & Distance modes

~UTS U niversity of Techno logy, Sydney

CS IR 0

URBAN

WATER

PROGRAM

Peak Levelling in Urban Water Reticulation Systems R J Shipton, CSIRO Building, Construction & Engineering Introduction

Table 1. Effect of peak levelling on reticulation costs

The Urba n W ater Program 1s mvestigating the use of storage tanks located o n residential pro perties to effect peak levelling o f de111and and thus achi eve substantial cost savings in the reticulatio n syste111.

The demand for water in urban supply sys te m s is co ntinu o us and co nstantly changing. The largest compo nent of use is no rmally residential, for which races o f de m and vary seasonally thro ugho ut the yea r. De111and ranges fro111 low du1ing cool w et pc1iods co high during ho t dry pc1iods with occasio nal ve1y high peaks caused by ga rden and la wn watering.

Conventio nal reticulation systems arc desig ned to meet th e peak instant or peak ho urly rate of de111and at the end of the design perio d. A typical diurnal desig n curve of peak day residential use for a me dium to large syste m is shown in Fig ure I. The peak instant dc111and is 2.5 times the ave rage rate for the peak day.

The cost o f the reticulatio n system required to deliver water is hig hest when the capacity of the netwo rk is based on th e peak instant rate and would be significantly lower if based o n the average rate. This reduction in design race could be achieved using a s111all pump o n each property with a storage tank w ith sufficient balancing sto rage . This 111cans tint the pipes for new systems need no t be as large and that retrofi tting tanks into existing sysce111s wo uld allow substantial expansio n into frin ge areas witho ut having to upgrade the existin g tail works systc 111 . H oweve r, the additio nal costs for the tank, pump and associated pipes and fittin gs muse be added.

Cost advantage of using peaklevelling tanks The follo wing cxa111ple co111pares the alternatives of providing single pipe reticulatio n syste ms with and without peak levelling tanks. The 111ini111um pipe size fo r

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Figure 1. Typical diurnal curve of peak day residential demand

Scenario

A

B

Description flow

Design cost (L/ hh/ hr)

Retic'n Tank/ pump cost cost ($/ hh) ($/hh)

Conventional single potable supply (no tank) DN100 minimum pipe size

312

3300

Single potable supply (with tank) DN100 minimum pipe size

125

1900

th ese syste m s is D NI 00 co provide a fire pro tection sysce111 based o n street hydrants at about I 00 111 spacing (WSAA ( 1999) Wate r R.e ci culaci o n Code o f Australia (WSA 03- 1999) Part 1 D esign).

Total

Saving

($/ hh )

($/ hh)

3300

900

2800

500

Tk â&#x20AC;˘ on-site tank, P â&#x20AC;˘ pump

arden

Figure 2. Single pipe supply to a dwelling with on-site tank and pump (scenario B)

For a typical design value fo r peak day residential consumptio n of 3000 L/ housc hold / day (L/ hh / d ), the peak instant design rate for the conventio nal syste m would be 3 000x2 .5/2 4 =31 2 L / /,i, / /,r(scenario A). A reticulation system supplying pea k levelling tanks with the sa me DN I 00 lower limit on pipe size w o uld have a d es ig n d e mand of 300012-1= 125 L//,/, / hr (scenario 13).

Mechanism for peak levelling The peak day demand o f each ho useho ld, for in- ho use and ex-house uses, is m et fro m th e tank, which is nicklc-filled fro m the reticulatio n system at a steady rate througho ut the d ay. The net effect of onsite storage is co reduce the peak flow design rate for the reticulation system by abo ut 60%, i.e. fro m a pea k factor o f 2.5 to l .0. A sche matic sho wing a typical tank and pump arrangem ent for a single pipe supply of po table water fo r all uses is shown in Figure 2.

The cost analysis (Tabl e I) is based o n supplying w ate r services to a cluste r o f 4000 ho useho lds in an area o f 3 km x I km using PN 16 class PE pipes. The potabl e water so urce was assum ed to be a service reservoir loca ted som e distance from th e cluster, with a supply hea d such that a head grad ient of about 4 111 pe r 1000 111 could be assumed for the dimibutio n and reti culatio n m ains fo r peak demand conditio ns. U sing a compute r program for h ydraulic analysis of water supply ne two rks, the pipe sizes w ere dete rmin ed to ensure, at peak demand , a minimum residual head of 15 111 (150 kPa) at th e lowest pressure no de within th e cluste r.

T he tan k and pump m odule has an estimated ca pital cost of $530, an annual cost of $62 includi ng ru nning costs, and an equi vale nt net present value of $900 usin g an effecti ve d iscount ra te of7% per annum.

The analysis shows u p a significant cost saving of $500/ hh or 15% fo r the pea klevelled system supplying 4000 houses, assuming cl1e installatio n is based on using standard trenching in sandy soil.

Discussion Further research is proposed to study the impact of peak-levelli ng fo r o cher situatio ns. It is to be expected chat the savi ngs will becom e greater as cluster size increases because whereas rank and pump costs are fixe d, disnibutio n coses arc higher, particularly w hen ground conditio ns are di fficult.

The cost benefi t of retro-fi tting tanks into existing systems co pe1111it network expansio n imo frin ge areas has considerable potential. The new fiinge area extensio ns would supply properties using peak levelli ng tanks, however, the pipe sizes could be limited co a minimum of ON lO0 with street hydra nts fi tted, o r, have no minimum pipe size limit and incorpo rate alternative arrangem ents fo r residential fire protectio n.

Additional savings could be made if a pressure reduction strategy was ad o pted for fringe area extensio ns that enabled the use of lower pressure class pipes.

The applicatio n of tanks to dual pipe system s may also be cost-effective , particularly if linked to the no n-po table lawn and garden wate1i ng supply.

WATER SEPTEMBER/ OCTOBER 2000

19

CS IR 0

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PROGRAM

Peak Load Management at WWTPS N A Booker, CSIRO Molecular Science The Challenge of Peak Flows

Technology

Sewage Optio ns to cope with peak flows Treatment Plant include: • impervious pipe systems: a high cost solution with minimal chance of short- term success.

• bypassing the treatment plant: low cost, but untreated sewage discharges Untreated Storm Bypass Flow to the environment Figure 1 . Conventional System • treating the peak flo w : low cost, bu t the biological processes are disrupted for long periods after the storm event.

• installin g ov e r-siz e facil iti es: expensive, with under-utilisation of invested capital.

• storing peak flows off line and treating them later: significant cost and aesthe tic implications.

• design ing processes to deal with the pea ks o nly, with lower capital Figure 2. Alternative Syst em but higher operational costs for those periods. react quickly to increased fl ows, and perhaps for seasonal peak flo ws, for This project aim ed to assess the example in tou rist towns. potential of high rate processes that can

Various au tho rs have proposed processes w ith t h at p o te ntial.

T hese include SIROFLO C™ (1), ACTIFLO™ (2), D ensadeg™ (3), CDS (4) and high rate filtration syst e ms (5). Th ey all rely on chemical coagulation, flocc ulation and rapid separatio n. They have effective hydrauli c loading rates 10 to 20 times faster than the 2m 3.m2. h- for co n ve nti o nal pri mary sed imentat ion and biol ogica l processes. C onsequen tly they have low plant size and capi tal costs, however, this is off-set by higher operating costs due to the use of chemicals.

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Cost Estimates The "conventional system" (Fig. 1) is usually designed to handle a flow equivalent to three times the average dry weather flow (ADWF) and comprises: screening, primary sedimentati o n , ext e nde d aerat io n , c h e mi cal phosphorus precipita tion, secondary clarifica tion, tertiary filtration and disinfectio n. Annual operating costs were based on a total flow to the plant of 1.2 times the ADWF. In the alternative approach (Fig. 2), the conventional plant is designed for the base flo w ADWF. A high rate physico-chemical process runs in parallel, sized to handle two times the ADWF, but operating, say, only 10% of th e t ime. It co mprises sc re e nin g, physico-chemi cal clarification , tertiary filtratio n , and disinfectio n .

Capital costs were estima ted for a range of ADWF plan ts under both systems and showed that the integrated biological and physico-c hemical system (Figure 2) could be constru cted for less than 50% of the cost of the con ventio nal biological plan t, per volume of w astewater treated. An analysis of the o peratin g costs sh owe d that th e 2.5 , - - - - - -- - - - - - ,

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40

60

ADWF (MUDay)

Figure 3. Cost of Treatment

20

WATER SEPTEMBER/OCTOBER 2000

80

integrated peak flow management system would cmt about 20% more to operate than the conventional system, per volume of ,vastewater treated.

It was assumed that capital costs could be amortised over 20 years at 5%. When this annual cost of capital was added to the annual operating cost, a cost to treat the sewage was calculated, as shown in Graph 1. As can be seen from this data, reductions of nearly 50% in the total cost of wastewater treatment were possible through the adoption of this integrated approach. The cost data represented in Graph 1 also shows that there is an effect of system size on costs, indicating that the maximum savings were for system sizes between IO and 40 ML/day.

Conclusions These results from the feasibility study show that there arc potentially large savings in the cost of wastewater treatment through the use of physico-chemical technology to cope with peak flows. These savings could be realised at new wastewater treatment plants, or where upgrades to existing treatment facilities arc proposed in order to cope with increased or seasonal hydraulic load.

It is proposed that these approaches be tested further through a demonstration study at a suitable, small sewage treatment plant. This would include: • Full evaluation of the technical and economic merit of the proposed approaches through the use of CSIR..O's design, flow and costing model.

• Assessment of the environmental outcomes of the bypass approach, compared to the construction and operation of a large plant that handles all the peak flow.

• Evaluation of existing technologies to suit the proposed applications • Modification or development of technology where current existing technology is shown to be inappropriate • Demonstration of existing and new technology options at a suitable test site The outcomes of this work will enable the water industry to utilise existing assets better and minimise the capital investment in new urban water infrastructure

References I 2

3 4.

5.

Booker, N.A. and Priestley, A.J. (1996): WaterTECH'96, pp 190-197 Guibdin, E., Ddsalle, F. and Binot, P. (1994): Chcmiral [Vatcr aud IVastcwatcr Trcatmcm - Ill, Proceedings of the 6th Gothenburg Symposium, Sept. 1994, pp307-316 Delporte, C., Pujol, R. and Vion, P. (1998): Http:/ /www.degremont.fr/ rd/proccdes/tech 7 .htm Becker, N.S.C., Booker, N.A, Davey, A., Gray, S.R., Jago, R. and Ritchie, C. (2000): Chemical Watl'/' and Wastcr11atcr Treat/II!'/// - VI, Proceedings of the 9th Gothenburg Symposium, October 2000. (in press).

Gray, S.R., Booker, N.A., Arid, R. and Lerch, A. (1999): Proceedings of the AWWA 18th Federal Convention, Adelaide, April 1999

CS IR 0

URBAN

WATER

PROGRAM

Economic Scale of Greywater Reuse Systems N Booker, CSIRO Molecular Science Communal systems The collection, treatment and reuse of greywater within the urban water environment has b ee n stud ied by num erous au thors. This desk study aimed at estimating the sca le at which communal greywater systems become eco nomically attractive, where the costs of treatment could be balanced by the costs of the distribu tion system, giving an overa ll minimum n et cost.

Method Five scales of greywater recycl e system were ana lysed, i.e. 12, 120, 1,200, 12,000 and 120,000 hou sehold connections. At each scale, a distribu tion network was design ed to collect th e greywater from each house and return the reclaimed water and a treatm ent process also designed to convert the greywater to a suitabl e quality for safe reuse. Th e general assumptions were: Households

• A household contains 4. 3 people • A p erson "produ ces" 150 L/ day of greywater and "consum es" 150 L/ day of reclaimed water (use d for toilet flushing, laundry and ga rden watering).

• A house hold is 15111 x 50111 i.e 750 1112 Greywater and reclaimed water distribution systems

• Greywater gravitated from a cluster of houses (4 or 12) to a storage tank. Tanks were pumped to the central treatment process, at a maximum head of 30111 with a peak capacity of 2 1n3 /h.

• Class PN12.5 PE pipe was used for all p ress uri se d g r eywa te r and tre ate d greywater pipes, pipe size determined by pressure drop and volumetric flow rate • Pipes were laid using plough laying tec hniques for pipe sizes from 25 111111 up to 150 111111. diameter. Larger PE pipes of 300 and 500 111111 diameter were assumed to be laid using conventional trenching.

• Each house had 10 111 of 25 111111 PE service pipe connecting th em to the reclaimed treated greywater mains.

Greywater Treatment

• Treatmen t of greywater was either by screen in g, chemical coagu lati on and tlocculation, sedimentation, sand filtration (CAS) , or by microfiltration (M F), both followed by UV disinfection and storage. Sludge was digested , pressed and 22

trucked off site . A number of scenarios were costed: Scenario 1. Greywater co llection in a separate trench to reclaimed water distribution. Trea tm ent of greywater by CAS. Scenario 2. As for Scenario l , except treatment by MF. Scenario 3 . As for Scenario 1, except the greywater co ll ec tion and recla imed water distribution Scenario 4. in the sam e p lo ughed trench.

Scenario 5. As Scenario 3, except the number of houses serviced by each greywa ter holding tank/ pump system was increased from 4 to 12 Scenario 6. As Scenario 4 except that MF was used for 12 and 120 household connections and at th e larger scales (1200 to 120,000) CAS was used.

Cost Estimation

techniqu es that allow two p ipes to be laid together in the sam e trench could result in lower costs.

Developing tec hno logy such as MF co uld move the cost minimum down to smaller scale system s. At th e larger end , eco nomies of scale for co n ventio nal processes beco me significant and treatment costs are reduced, per volume of water trea ted.

Conclusions T he minimum cost to opera te a reclaimed greywater water system , based on th e cost assumptions used in this s tudy , was ab out $0 .5/ m~ . Thi s compares favou rabl y wi th th e cost of potable water delivered to most homes in Australia n cities (eg. M elbourne $0 .7 to $0.8/111~). This ma y m ea n that co mm unal greywater recycle systems, design ed to service cl usters of 1,200 and 12,000 house holds, cou ld be econom ically viable. There are significa nt extra benefits, which have not been included in these costings i. e . reduced demand for potable water, and reduced flo w of sewage.

Further work is required to demonstrate that the treatment technologies proposed are capab le of m eeting the quality requirements of reclaimed water and to determine the net environmental impact of greywa ter recovery and reuse.

Figure 1 for Scenario 1 shows clearly that a minim.um total cost per household resulted from the balance between treatm ent and transport.

T he ope ratin g costs for th e five sce n arios were based on assumed maintenance rates for the pip e systems, power for pumping, and op eration and maintenance of the treatment plant. T he maintenance costs need to be verified from actual costs. T he capital for each system was amortised at 5% over a 20yea r period.

Dividing the annual cost by the vo lume of - -Transport -+-Treatment ...,.. Total water treated each year gave a theoreti cal cost for reclaimed water (Figure 2).

At th e scale where costs were a minimum, op e rating cos ts w e re distribut ed b e twee n distribution sys t em Number of connections maintenan ce (2 5 %), pump power (10%), treatFigure 1. Capital cost per household under Scenario 1 ment plant ope rat io n (10%) and amortised 8.00 ..--- -- - - - - - -- -- - - - - - - - - , capital (55%) . 'f 5.00 ___.. Scenario 3 Th e mi ni mum cos t ~ 4.00 comes for systems within J!! ; 3.00 the size range 1,200 to 12 ,000 co nnect ions . ~ 2.00 0 Above th is system size, 0 1.00 the transport costs were 0.00 1---- - - - - - - - -~---~-----i dominant, below about 1,200 connections treatNumber of connections m ent cos ts dominated In novative pip e laying Figure 2. Total cost of water for Scenarios 1 to 5

WATER SEPTEM BER/OCTOBER 2000

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CS IR 0

URBAN

PROGRAM

WATER

Septic Tank Replacement S Gray, N Booker, CSIRO Molecular Science Septic tanks have long been used for single dwellings and in small , dispersed communiti es, where connection to centralised sewerage systems was too expensive. Over time many of th ese co mmuniti es ha ve grown an d th e environm en tal effect of se ptic tank discharge has become an even greate r problem. In many locations throughou t Australia, such as rural Victoria and tow ns alon g the Hawkesbury-Nepca n River, septic tan ks are b eing replaced with conventional wastewater coll ection Th e Urban Water Proj ect syste ms.

(UWP) in vestigated wh ethe r alternative sewerage system designs cou ld produce the sa me or a better ou tcome at a lower cost.

Seven different wastewater coll ection and treatme nt syste ms were compared and cap ita l cost data collected for pi pe installatio ns and treatment technologies.

The nutrient lo ads disc harged co the e n vironm e nt were estimated from published data relati ng to nutrie nt loa ds from household sou rces and fro m the cffiuen t qualiti es of a range of differe nt treatm e nt technol ogies .

A hypothetical site of 10,000 people, o n the urban frin ge of a maj or city was considered . Th e c haracteristi cs of th e site are shown in Table 1.

Th e six system configurations considered in th e analysis and the assumptions mad e fo r eac h of che m arc shown in Table 2.

T h e qua lity of treate d e fflu e n t required fo r discharge was assumed to be <0.5 mg/L total- P, < 5 mg/ L tota l-N and < 150 cfu/ 100111I. Exfil trati on and sewer overflows were ignored in th e scenari os, and a peak flow facto r of 1.94 was used in sizing o f the pipes.

Table 3 shows cap ital cost estimates (transport and treatme nt} and th e nutrien t discharges of each approach. It was assumed that septic tanks had zero re moval e ffi c ie ncy fo r nitroge n and phosphoru s because in these system s th e main uptake of nu trie nts is by vegetative growth subsequent to the septi c tanks, w hich is an extremely variable and ineffi cient process.

All approaches are an imp rovement o n septi c tanks, with be tter than 90% of the nutrients removed in each case.

Localised treatment of sewage, eithe r as a combin ed strea m or as separate blac kwater/grcywater streams, was cheaper than the ce ntra lised approac h, in th is

24

instance. T he treatment of blackwater alo ne was very effec ti ve, wi th remova l efficiencies o f 92% N and 87% P predi c ted and at an estimated 40% of the capital cos t of th e co n ve ntional approach.

T he applica bility of each approach will be dictated by the lo cal co nditions, as it

Table 1. Hypothetical site characteristics Population Household connections

10,000 4,000

Average no. people/house

2.5

House density (houses/net ha)

16

Distance to centralised sewerage system (km)

20

Distance to local treatment plant (km)

1

Table 2. Scenarios considered and the assumptions made Scenario

Assumptions

1. Sewage is collected and transported to a large treatment plant 20 km away.

• Gravity sewerage system • Sewage treatment = screening/ primary sed imentation/BNR/chemical precipitation/sand filter/ UV disinfect • Sludge treatment = anaerobic digestion/ belt press • Existing central ised sewage plant was upgraded from 50 ML/day to 55 ML/day to accommodate the extra flow.

2. Sewage is transported to a small, local treatment plant and t he treated effluent discharged to the stormwater system.

• Gravity sewerage system • Sewage treatment = screening/primary sedimentation/BNR/ chemical preci pitation/sand filter/ UV disinfect • Sludge t reatment = anaerobic digestion/belt press • Capacity of the local treatment plant= 5 ML/ day.

3. Only blackwater is collected and treated at a local treatment plant, while greywater continues to be discharged as seepage on household blocks.

• Pressurised sewerage system with no infiltration • Blackwater treatment = anaerobic digestion/ chemical precipitation/ biofilter/sand filter/ UV disinfect • Sludge treatment = belt press • Capacity of the blackwater treatment plant= 0.4 ML/ day

4. Greywater and blackwater are collected as separate streams and are treated separately at local treatment plants. Separate pipes are used for the collection of greywater and blackwater.

• Pressurised sewerage system for bl ackwater & gravity sewerage system for greywater.

• Blackwater cost as for approach 3.

• Greywater trans port cost same as for case 2.

• Greywater treatment = screen/coagulationflocculation/ sedimentation/sand filter/ UV disinfection • Sludge treatment = belt press • Capacity of the greywater treatment plant = 4. 7 ML/day

5. Greywater and blackwater are collected as separate streams and are treated se parately at local treatment plants. A single pipe system is used but blackwater and greywater are kept separate by scheduling of f lows in the pipe.

Blackwater is collected in the existing septic tanks during the day and is pumped out at night during periods of low greywater f low.

6. Existing septic tanks where greywater and blackwater are treated on-site, and the septic tank discharge is via a sub-surface soakage pit.

WATER SEPTEMBER/OCTOBER 2000

• Treatment costs for bl ackwater & greywater t he same as case 4.

• Blackwater gravity collected in existi ng septic tank and pumped in to the sewerage system at night.

• No reduction in nutrient loads in septic tank system.

CS IR 0

URBAN

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Table 3 . Comparison of wastewater system configurations. (assumes 4 ,000 connections = 10 ,000 people) $/ house

N discharge (kg/ yr)

P Discharge (kg/ yr)

1. Conventional sewage treatment - remote from centralised sewerage system.

6,160

2,300

230

2. Conventional sewage treatment localised treatment.

5,450

2,300

230

3. Local ised biackwater t reatment

2,325

4 ,570

847

4. Localised blackwater and greywater treatment with each collection in separate pipes.

5 ,725

2,300

230

5. Localised blackwater and greywater t reatment with scheduled flows of blackwater

3,240

2,300

230

54,000

6,500

System

6. Septic tanks (no effective removal of Nor P).

* includes stormwater discharge

* assumes separate pipes for transport of greywater and blackwater.

+ assumes a single

pipe with scheduling of flows for transport of greywater and blackwater.

m ay be better to transport the effiu ent awa y rath er than discharge it to sensitive loca l en viro nm ents.

H o wever, the scenari o process allows the meri ts of each co nfi guratio n to be readil y assessed.

Th is work demo nstrated tha t there are lower cost altern ati ves to in- fill sewe rage sc he mes for frin ge urban areas th at are still o n septic tan k syste ms.

Th ese altern atives ca n achieve better

The Urban Water Program called on a number of CSIRO Divisions, and some projec ts have not been reported in this feature.

The principal researchers are: • Andrew.Speers@dbce.csiro.au , Pro gram Direc tor: North R y de,

NSW • Geoff.Syme@per. clw .csiro.au, D o mestic W ater U se Study, C hange Fa ctors, Barriers to Acc eptan ce: Floreac Pk, WA • Shiroma.Maheepala@dbce.csiro .au , Water Balance Study: Highett, Vic • Stephen .Gray@molsci.csiro .au, Con taminants & Nu t ri en t Flows: C layton , Vic • Stewart.Bum@dbce.csiro.au , Life C ycl e C os tin g, Wa t e r Sys t e m s Externalities: Highett, Vic

than 90% reducti on in the disc harge o f nutri ents to th e environm ent and w ill allo w fo r local reuse of treated effiuent.

Th ese co ncepts need to be tested at a ran ge o f system sizes and th eir en viron Further men tal impacts qu antified. wo rk is proposed that wo ul d allo w CS IR.0 and the w ater ind ustry in co llabo ration to refin e th e be nefi ts identifi ed here .

• Susan.Cuddy@cbr.clw. csiro. au, Model Development for Wastewater, Stormwa t e r Sce nari o M a nage r Software: Black Mountain, ACT • Bob.Ship ton@ dbce .csiro. au, Peak loads in the water distribu tion system: Hi ghett, Vi c • C hristopher.Zoppo u@cbr.clw. csiro.au , Scenario man ager software, Model Development for Wastewater, Stormwater: Black Mountain, ACT • Grace.Mitchell@dbce.csiro.au , UVQ developmen t: H ighett, Vic • Selwy n.Tucker@dbce .csiro. au, Life cycle costing: Highett, Vic • Mike .Young@adl.clw .csiro.au , Cos ti n g of e x ternaliti es : Gl e n O sm ond, SA

• N ic.Booker@ molsci.csiro .au , Alternative Approaches: Clayton, Vic

• Michael.Reed@cbr.clw .csiro.au, Scenario man ager softwa re: Black Mountain, ACT

• T ony.Priestley@molsci. csiro.au, Sce nario D e velopment, Sce nari o Analysis: C layton, Vic

• John.Coleman@cbr.clw.csiro.au, Scenario manager software : Black Mountain, ACT WATER SEPTEMBER/OCTOBER 2000

25

WASTEWATER

WATER RECYCLING J Anderson, National Convenor of the AWA Water Recycling Forum T he Australian water accoun ts, which th e Australian Bure au o f Stati sti cs released recently, sho w a big increase in the use of recycled water in Au stralia during th e 1990s. T he ABS w ater accounts for 1996/97 indicated reuse of 134,400 megalitres per annu m . The am o unt of reuse continues to grow .

R euse of trea ted w astewater for agricultu ral irri gatio n continues to be the largest category of reuse . The proj ects range fro m the very large, like the Vi rginia Pip eline Schem e in So uth Australia, to small local proj ects.

The arti cles commissio ned by Bob Swinton for this issue o f Water showcase just som e of projec ts. It sho uld be noted that these range fro m ' T o tal R e- use ' w here storage duri ng wet wea th er is a major issue (see Gardn er et al, " Water", May /Ju n e) to o pt io nal u se w h er e un used effiuent is discharged to receiving wa ters. Th ese are two different philosophies, but it is hoped that the latter will steadily shift to th e fo rmer.

W hen I served on the judging panel o f the Irrigatio n Association ann ual awards earlier this yea r, it struck m e that there is a largely- hidden world of water recycling w here som e quiet ac hi evers ha ve put together so me rem arkable success stories . No ne of the fo u r proj ects in the !AA awards was large. But coll ectively such projects ac hieve a substantial volume o f beneficial reuse and m ake an impo rtant contributio n to sustainable water managem ent. I suspect that m uch of this type of reuse is unrepo rted in the current Australian statistics on water recycling.

Water R ecycling Australia 2000, th e 1st Au s trali a n W a t e r R e cy cli ng Co nference, will be an opportuni ty to lea rn abo ut the latest and best wa ter recycling developmen ts in Australia.

The Conference w ill be held at the Rad isso n Pla y fo r d H o t e l, N ort h Terrace, Adelaide, South Australia, on 19-20 O ctob er 2000. T he C onference Th em e is R ecycled Water: A11 Essential R eso11 rce for the New l\llilleni11m . T here is a w o rld cla ss co nferen ce pro gram including a half day w o rksho p o n m anagem ent of hea lth risks, technical to urs of the Virginia pipeli ne schem e, residential water recycling and groundwater recharge proj ects. T he Keyno te Speaker is M r Keith Israel, General

26

M anage r o f the M o n terey Co un ty Authority an d driving force beh ind th e land ma rk M o nterey C ounty Wate r R ecycling Scheme w hich uses recycled water to irrigate S000ha area o f salad and vegetable crops in C alifo rnia 's Lower Salinas ValJey. T here are a fu rther 16 platfo rm papers and 21 poster papers spanning the bread th of w ater recycling activities in Australia.

Water recycling is just one aspect o f d eve lopm ents in sustainable w ate r managem ent in Australia. Ano ther is the development o f integrated urban water planning. T he flagship of this work is the landmark CS IRO U rban W ater Study.

Andrew Spee rs drew m uch fav orable comment with his presen tatio n at the rece n t In ternacional W ater Association C ongress in Paris.

In NSW, pilot studies o f integrated wat e r , s e w e ra g e a n d stormwa t e r

WATER SEPTEMBER/OCTOBER 2000

plan ning as part o f D LW C's W ater R efo rm i niti ati ves ha ve id e n tifi ed oppo rtunities w hich were not apparen t w hen separate strategies were developed fo r each service. T he result is better integrated, m ore sustainable and lower cost solutions.

A us tra li an wate r recyc ling an d sustainable wa ter managem en t initiatives are held in high regard overseas. M y recent elec tion as C hair of the IW A S p ec iali st Group o n W as t ewat er R eclamation , R ecycling and R euse is j ust o ne manifestation of this. But the real credit belo ngs with all the unsung local heroes who have persevered against the odds to deli ver their local wa ter rec ycl ing proj ec ts. What has bee n achieved collec ti ve ly o ver th e last decade is something of which we ca n all be proud.

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Paul Turner (08) 9220 9300 SA

Paul Lindon (08) 8271 2322

WASTEWATER

Abstract The Willunga Basin Pipe lin e in South Australia is a pri vate ly funded reclaim ed wate r scheme with so me innovative e n g in eerin g features. Stage 1 was co mpleted in 1999 and over the 19992000 season it has successfu lly serv iced th e 15 water users, mainly viti culturists, w h o fund ed the schem e . D espite the high cost of access ing th e wate r, and despite the fact that in Stage 1 the use rs have sa tisfied all th eir o n-fa rm water nee ds, provisions were in c luded for expansion . The fi rst of the expansio n phases is being impl emented in 2000.

Eventually the sc he m e may expa nd fi vefold, possibly closing down th e Christies Beac h effiu ent outfall to sea.

Introduction Th e Wil lunga Basin is imm e diate ly so uth of me tropolitan Adelaide, and is generally defined by the surface water ca t c h m e nt boundar ies t h at dra i n westward to the sea. The Willunga Basin is n oted for recreatio n and tourism associated with its vineya rds, almond orchards and beaches. It is home for 50 w in eries and th e world-renowned M c Laren Vale grape-growing region.

The C hri stie s B each W as tewate r T reatm ent Plant (CDWWTP) is 10 km north of the Willun ga Basin , and is one of 4 me tropo li tan trea tment works. Th e annual 'waste' flow to sea is greate r than th e annual abstraction of groundwater for irrigati on in th e B asin.

Th e Willunga Basin Water Company (WBWC) was formed from a number of

wate r use rs, who have fu nd ed th is schem e to all ow them to pursue their core business of irrigated hortic ulture (mostly viticu lture) . Based on proj ect p lan s provid e d b y H ydro - Plan the compan y has built a pipeline from CBWWTP to o utlets o n the farms, and w ill ow n and operate th e sc h eme themselves.

The Willunga Basin The Willunga Basin is bounded by th e Onkaparinga R.i ver to the north, and th e Sell ic ks Hill R.an ge to the south and cast.

Approxi mate ly 75% of th e basi n is elevated between 20111 and 100111 AHD. Th e remainin g 25% to the north-east is elevated be tween 100111 and 180111 AHD. R ai nfall is re liable in the Willunga Basin, and va ri es fr om 400mm to 700mm p.a. with averages around 550mm, being lower towards the coast. Evaporation varies from 1350111111 to 1850mm , w ith daily averages for J anuary around 9 mm.

Many so il types are found in the Basin, from red brown loa ms to gra velly ironstone, self- mulching crac kin g clays and sa nds over clay. T hese soil s support a w ide range of horti cu ltural crops.

The prim ary irrigati o n area o f the Willunga Basin was defin ed as 13,341 ha in a 1996 study by H ydro-Plan. About 48% of this area (6460ha) was used for grazing and c ro pping in 1993, and the maj ority of this would be suitable for irrigated horti culture. O f the 4107 ha licen sed fo r irrigation with groundwater in 1990, 69.1 % was for w in e-grapes and 17.7% for almon ds. There was sufficie nt

suitable land for n ew vineyards, but insu ffic ient w ater.

Regional Water Resources Groundwater is the most dominant water resource for t he region, and it is heav ily u tilised fo r irrigation. The grou nd water resou rce was pro claimed in 1990 under the Water R esource Act (1990) and licences to irrigate o n a crop area basis took affect fro m J anuary I, 1991. A crop-area licence limits the area but not the volume of groundwater use.

It is an inte rim m easu re successfull y used previously in South Australia to enable monitori ng and management initiatives time to wo rk .

The tough regulato ry decision needed to conve rt crop-area licences (ha) to vol um etric li ce nces (M L) has been delayed many tim es. Average groundwater use is higher than the sustainable yield of th e loca l aqui fers. The curre nt proposal is for a limi t of 1.1 M L/ ha (110mm per an num), which is considerably below what many wou ld like to use .

So w hilst othe r areas in Australia have ex pan de d r api d ly, irr igation u sing grou ndwater in the McLaren Vale region has been restricted to the 1990 level.

T his has crea ted a sharp awa re ness of the val ue of water, and pressure on all water resources.

Surface water is generally not accessible or not sufficien tly reliable in the Willunga Basin to be a signi fica n t resou rce . M ains wa ter access is very limited an d heavily utilised w herever it is available. With recent falls in groundwa-

WATER SEPTEMBER/OCTOBER 2000

27

WASTEWATER

seco n dary treatme nt . The treated wastewater is disinfected with chlorine prior to leaving the plant. After chlorination , the majority o f the flow is discharged to sea via a 400 metre outfall p ipe. The average discharge is approximately 26 ML/day or 9,500 ML per year.

A small quantity of water is used within the plant for flushing equipment and irrigation, and some is used to irrigate nearby council reserves and a school oval. SA Water has licensed the remaining flow to th e Willunga Basin Water Company.

Project Delivery Regional Map of the Willunga Basin Stage 1 area

ter level and quality, so me vineyards are buying mains water at $900/ML then ca rting it by tan ker. Th e small amou nt of reclaimed water available fro m a new wastewater treatment plant at Aldinga is barely sufficient water for one vineyard.

Reclaimed water co ll ec ted from Wi llunga, McLaren Vale and McLaren Flat townsh ips only amounts to abo ut 250ML per an num, and is mostly used on the Willunga Golf Course.

Table 1 draws from data in the Onkaparinga C at chment Water Manage me n t Pl an by PPK Environme ntal & Infrastructure for the On kap a r in g a Ca t c hm e nt W ate r M anagement Board. for th e Wi llunga ca tchm e nt. It demonstrates the degree of dependence on groundwater, and th e significance of the Willunga Basin Pipeline.

Christies Beach Wastewater Treatment Plant CBWWTP 1s a co n ven ti onal activated sludge plant, constructed in 1971 and extended in 1981 . Its design capacity is 110,000 equivalent perso ns (60g/ p/ d) and is ma tched by the current load. The actua l contributing populati on is approximately 13 5,000 persons in a catchment area of 13,000ha. H owever significant hydrauli c modifications, add itional air compressors and additional final c larifi e rs provid e suffici e nt additi onal ca pacity in th e short term. An en vironm en tal imp rovement program (E l P) has bee n prepared to upgrade treatmen t performance, including nitrogen removal , and is due for com pletion

by December 200 1.

Treatment includes sc re ening, grit removal, p re -aeratio n and primary se ttling , followed by co n ventiona l 28

The Willunga Basin Pipelin e shares many features with its predecessor, the 43km Langhorne C reek Pipeline which was co mple ted in 1995 to delive r 40ML/ d from Lake Alexandrina to 52 outlets in the Angus B rem er region near the R iver Murray mouth. Forty almond, grape and lu cerne growers of the region supplemented their degraded groundwater supplies by co nstru cting a jointly owned commun ity scheme .

1) A joint venture vehicle was used to maxim ise tax effectiveness .

2) The sc hem e is completely funded, owned and operated by th e water users.

3) All ou tlets can operate together.

4) Pumps and power su pplies are not needed o n- farm.

5) Water storage is not needed on-farm.

H ydro- Plan were the designers and project managers for both proj ects and work ed closely with a local champion, which fo r the Willunga project was Vi c Z erella of Tatachilla Winery.

As many peop le from the community must be brought together, it is important to have a simple 'ope n- boo k , not-forprofit' approach to project delivery, and tight budge t control. It was no accident that th e final cost was al most exactly equal to the original estimates.

It 1s a lso impor t ant to maximise the va lue and securi ty of th e water. From a water user's perspective, there is nothing better than being ab le to turn on th eir tap w hen th ey want.

Although the water users have fu n d e d 100% of th e $7.2m needed to bu ild the pip elin e, they have only all ocated themselves 25% of the water it can deliver, that is, the summer flows. This helps satisfy thi rd party access

WATER SEPTEMBER/O CTOBER 2000

requirements and allows for expansion to other areas in the Willunga Basin, without duplicating the main pipeline.

Th e surplus w ill continu e to flow to sea until others are prepared to expand the scheme . To do so will require storage of the winter flows, either above or below grou nd , and by extending the pipe network to the east and south.

Access to Reclaimed Water The first major obstacle w as obtaining access to the water. Government departments were unsu re w ho owned the water and how to make it available. After almost a year of plea ding to va rious agenc i es and interes t groups, the Government called tenders for the right to negotiate for the water on the basis that no Government fu nding would be available . H ydro-Plan developed the engineerin g concepts and a budget so that Vic Z erella could approach enough landholders and water users who were w illing to form a group and submit the successful bid. Four large firms in volved in out-sourced water projects were also asked to bid.

The lack of Government funding on this project contrasts to the Virginia reclaimed water schem e to the north of Adela ide where va rious Government entities have contributed over $40111. Vic Zerella notes with pride that he was one of ma n y growers at Virginia w h o attended reclaimed water m ee tings for 25 yea rs, but th e Willu nga Schem e was the first to pump water. Although the cost of accessing water is much higher than at Virginia, the proj ect proceeded quickly

Before

and after the new Virginia Pipeline.

For years, local farmers and market gardeners

at Virginia with 20 billion litres of Class A irrigation

h ave relied on ground water f or irrigation.

water each year. (An amount similar to current ground

Unfortunately, t his has impacted on supply and

water consumption and the equivalent of 50-70% of

increased salinity levels. Happily, the commissioning

the outflow from Bolivar Treatment Plant.) The net

of the largest wastewater reuse schem e of its

result will be a vastly reduced outflow of nutrients

type in Australia w ill reverse this trend .

from Bolivar into the sea, much lower demands

The new, sophisticated Dissolved Air Flotation Filtration treatm ent plant and the Bolivar to Virginia Pipeline Government of South Australia

are supplying market gardeners

on ground water resources and the prospect of growing a $250 million indust ry in the area.

' t SAWater

The Virginia Pipeline Scheme is a collaboration between SA Water, Water Reticulation Systems Virginia, the Virginia Irrigation Association, and the Government's Major Project Group.

WASTEWATER

infrastructure projects.

This was very helpful in that it provided a coord inated m echanism for each Catchment rainfall volume 159,600 ML r egulatory authority to Imported mains water for urban use 3,800 ML have their say, and for a Exported untreated effluent 1,500 ML whole-of-Governm ent Stream discharge to sea 12,000 ML approach to a project that Irrigation groundwater use 7,500 ML had virtually no preceIrrigation diversions from streams dents to work from.

1 ,000 ML Mains water used for irrigation 200 ML An Irrigation Managem ent Plan is a key part of Reclaimed water from Ald inga and Willunga 300 ML the appro val process for reclaimed water use in and the water users are in control of South Australia. The IMP is based on their pipeline. comprehensive guidelines, submitted to The user group won the right to the EPA and updated annually. Other negotiate with SA Water in October agencies such as Primary Industries and H ealth Commission are involved in the 1997, a year after first asking them to access the water. As a Governmentprocess. Th e objective of this owned corporation , SA Water rightly Irrigation Management Plan (IM P) is to has a charter to make a profit at every describe the sustainable management of opportunity. Negotiations took a further the reclaimed water irrigation scheme. It 4 months but a 40 year licence agreetakes into account the physical features ment was signed in January 1998. A of the sites to be irrigated, soil characteristics, impact on surface and groundfurther 6 months of n egotiations waters, and public health. followed to obtain design approval prior to tender, and then another 6 months In o rder to put the project off on the for construction approval for the interright footing, best irrigation practice was face at the water diversion point. Water adopted throughout. Detailed so il was pumped through the pipeline three su rv eys usin g backhoe pits were months later. conducted on a 75m grid for all irrigated areas. Hydro-Plan design ed new o nThe Willunga Basin Pipeline is delivfarm irrigation systems, reviewed existering benefits to SA Water by mitigating ing systems, and designed headworks. storm water flows, thus delaying th e urgency of upgradin g the ocean outfall.

Soil and crop managem ent reports were The pipeline is redu cing the discharge of commission ed and se mi na rs were pollutant load into th e Gulf St Vincent, conducted. thus helping to meet the commitments A detailed Deed and Permit was of their $2 10m Environm e ntal negotiat ed w it h the City of Imp roveme n t Program. SA Wate r Onkaparinga. This process included an needed to be confident that the scheme independent engineering design review . would be successful, and that appropriWhilst the pipeline mostly travels down ate standards were adopted. They also public road reserves, easem ents were se t required provisions for third party up on all Council and private land. access, water price escalation and indemEngineering Summary nity.

Th e pip e lin e is designed for Other Approval Processes 24ML/day, the minimum efflu ent flow The user group fo rmalised their joint in summer. All of this flow-rate is ve nture and formed the Willunga Basin committed to th e water users who own Water Company to build and operate the pipeline. The pipeline could deliver the scheme on their behalf. The concept all of the treated wastewater flow to the of 'a R ecycled Water Unit' was introWillunga Basin, thus alleviating pressure duced. This draws parallels to crop-area both on groundwater and pressure on water rights (lRWU is better value than the marine environment. a 1 acre groundwater licence), simplifies T o balance plant effluent flow during the basis of contribution (there are 1500 the day, a 6ML polyethyl ene lin ed dam R. WU 's in Stage 1) and represe nts the was built at th e Christies Beach wasterights to access flow-rate and annual water treatment plant. The plant is volume (1RWU=1.4ML/a). operated by United Water for SA Water Once the primary elem ents were in so joint access arrangements were develplace, an app li cation for planning oped. Water flo ws into the dam by approval was submitted through a fastgravity through a pipe which is just tracking process reserved for significant upstream of a simple weir constructed Table 1. Major Water Transfers in the Willunga Catchment, per annum

30

WATER SEPTEMBER/OCTOBER 2000

between the chlorine contact tank and the outfa ll. Any water not required by WBWC will spill over the weir out to sea as before.

The fi rst pump station has three ide nti cal Batescrew 9-stage vertical turbine pumps fitted with Teco 4-pole 150kW motors operating at fixed speed to fill a 12ML dam near Old Noarlunga which was constructed using the spoil from CBWWTP. This dam allows for off- pea k pumping, a buffer for maintenance o n the 10.5km. rising ma in through the built up areas, and opportunity for water quality management. The pumps operate at heads up to l000kPa as required by an algorithm that maximises pumping during off-peak power tariffs.

The vertical lift between dams is 52111, and the highest outlet is a further 30111 above the upper dam. The dams are 10.5km apart, and the first outlet is 15km from the source.

The main rises sharply by 48m in the first 1.2km so a one-way surge tower was located at the high point to reduce refilli ng cycle times. Following a requ est from Council, the initial proposal for a 2111 diameter 6111 hi g h tower in a Council park was re-design ed by H ydro-Plan. A buried horizontal tank made from 1.5111 concrete pipes with a 6111 high 300mm diameter vent pipe was co nstructed instead. T his 'tower' has low visual impact and because it was laid horizontally, was able to fit into a narrow median strip.

Multiple pumps in paralJel are used for reliability and effic iency. A computer automatically controls and monitors the system and dials off-site if a problem occu rs. The distribution pumps automatically respond to demand using variable speed co ntrols to maintain high energy efficiency. The distribution pump station at the base of the l2ML dam uses iden ti cal Batescrew pumps but with 7-stages and 132kW motors, and a 37 kW j acking pump , maintaining constant pressure by a PID drive on the speed of one pump. APC Systems E ngineering suppli ed the m otor drives, control and telemetry equipment and engineered the control system.

The pipe was manufactured by Iplex in Sydney usin g modified polyvinyl chloride (mPVC). T e nd e rers a lso proposed DIC L, ABS and MDPE pipes.

The total 24km long pipeline includes 20km of 450mm AS 1477 Series 2 (508mm. outside diameter) pipe in class 12 and class 9 to the far end, and 4km of Series l spur mains in sizes 300mm, 200mm and 150mm in class 12 and class 9. The pipeline is buried 0.8111 to 1.5111

WASTEWATER

b elow ground. It is ba ckfilled with compacted ,a nd , and h as a meta lli c 'warning tape' above it for lo ca ting it.

The pipe is colou red lilac (purple), th e international colour for reclaimed water, and it is labelled every few metres with 'Willu nga Basin Water Com pany ' . T he pipe has rubber ri ng pressure seal joints eve ry 6m to allow fo r temperatu re and so il changes. Fittings are made from stainless steel and ductile iron coated with nylon, and wrapped petrolatu m systems to specifications used by SA Water fo r service life beyond 100 years.

The fi ttings were supplied by Crevet.

CATCON con tra ctors co nstru cted the sch em e using a labou r fo rce of around 50 people in the six m o nths between Septem ber 1998 and April 'I 999 . The pipe was tested to pressures well above normal, and was operational in April 1999. The Govern o r of So u th Au stralia, H is Exce llency Sir Eric Neal, officia!Jy opened it on Au gust 27, 1999.

Al l of the 17 outlets can be fl owing at once, with enough pressure for growers to o perate their drip systems. Th is h igh leve l of se rvice avoids the ne ed for growers to store water in dams o n their own properties, and it avoids th e need for power and pumps at each ou tl et.

Water users provided their own equipm ent downstrea m of o utl ets, including automati c fil tration and backwash water manage ment system. Each ou tle t has a flow meter and data logge r to constan tly reco rd flo w. T he flow records are a valuable wa ter ma nage ment tool and a way o f sharing pu mping costs.

T he fi nal $7.2111 co nstru ction cost was right o n budget. Som e of the 850ha irrigated by Stage 1 were converted from mains water an d sali ne bo re water, but the majo rity were newly d eveloped vi n eyards. Th e pipelin e wo uld have in itiated tota l in ves tm ent of arou nd $30 111 when the new suppl y became assu red . In the first (1999-2000) growing seaso n 950 M L was pumped to growers at a cost of arou nd $300/ML. T he high initial cap ita l cost w ill be offset even tu ally by lower costs assoc iated with selfown ership .

T he Willunga Basin Water Company has a full time water supply officer to maintain and m o nitor the system and to meet the requirements of the EP A. He is equi pp ed with a laptop computer, water ana lysis equ ip men t and mobil e p hon e so he can access the SCADA system and ren10tely check on operations.

Expansion Plans Even as Stage 1 of the p ipelin e was

being com pleted , plans fo r Stage 2 we re being developed. But it is important to realise that those wh o finan ce d and built th e pipeline largely satisfied their own req u irem ents for water and have since become full y committed to developing th eir own new vineyards. N everth eless, a small expansio n before the 2000-2001 season w ill lead th e way for m ajor expansion soon after. All landowners in the Stage 1 area were given the opportunity to participate initiaLl y, b ut there were a few w ho were unable to participate at the time , but are now being conn ected befo re th e 2000-2001 season . This expansion has taken considerable soulsearch ing because th e initial 'group of water users' had to transfo rm into a 'water distribu tion company ' to ensure they do not j eopardise their own in vestment on-farm and off-farm . l t is hoped that between 10km and 20km more distribution pipes will be laid for the 2000-2001 season. Th e reve nue from sale of water wi ll be all ocated fo r a surface storage dam. Th e alternative o f aqui fe r storage and recovery may still be a possibili ty but is very dependent o n EPA approva ls. Pre li mi nary ind ications are that the cost of expa nsion wi ll be feasibl e but limited to larger growers.

H oweve r, if the Governm ent were to provide financial assista nce, it would be viable for more growers to j oin an expand ed sc he me . This would increase the am o unt of efflu ent re-use, redu ce po ll ution o f coastal waters, red uce the amount of water pumped from the Ri ve r Murray, and reduc e stress on gro u ndwater and surface water resou rces. U nless such assistance is timely and structu red productively, the opportun ity will be lost.

•

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Conclusion T his project has se t a ne w bench mark fo r irrigation proj ects in Australia . It demonstrates w hat ca n be achi eved when communities are gi ven the tools to solve their own probl ems, and that all water, incl udi ng 'waste' water has greatest valu e when it is delivered in an attractive manner.

Author John Gransbury, since graduating from Adelaide in 1979, has designed and supervised large irrigation projects in the Midd le East and S E Asia as well as Australia. He started H ydro- Pl an in 1986 and now has offices in Adelaide, Perth and Sydney. 7 / 62-66 G len O smo nd Road , Parkside SA 5063. T el (08) 8373 4949 email us@hydroplan.co m .au

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WATER SEPTEMBER/ OCTOBER 2 000

31

WASTEWATER

WASTEWATER REUSE: A PRACTICAL VIEWPOINT A Murphy and J Murtagh Abstract T his paper summarises a practical vi ewpoint aimed at stimulating disc ussion and lists a nu mber of points which shou ld be reviewed, early in the feas ibility p hase, by mode lJers, designers, agricultural specialists and most importantly persons w ith practi cal experience and potential operators.

The points may seem insigni ficant in isolatio n but in practice they may have major impacts on t h e long-te rm v iab ility an d environmental sustainabili ty of wastewater reuse proj ects and must be seriously considered in a w elJ -planned and coordinated manner.

Keywords: E ffiu ent reuse , waste water management, irrigation strategy, efil uent storage manage m ent, soil moistu re deficit, practical implem entatio n

Introduction O ne of th e main challenges fo r wastewater re use by irrigation is to e ffectively manage these sch em es over the long term . A review of many studies and formulation of acti on plans fo r their implem entation has highlighted several short-com ings in the preparation of the studies.

This paper discusses the impact (from a practical viewpoint) that the folJowing key design factors have on waste water systems and highlights th e critical need fo r an integrated approach to such design.

Factors

• Irri ga tion system s must be designed around th e param eters used for the hydraulic design to avoid overload in practice and w hat irrigation fr equ ency and strategy is best.

• lf night-only irrigation is to be recomm ended, has its impact been conside red PRIOR to modelli ng and design?

• ls the schem e to be managed by experien ced wastewater man age rs o r leased or agisted to surrounding farmers what are the major consequences?

• ls full contract managem ent an option ' • What capacity must a system have to enable correct operation?

• Ho w sho uld w e t weathe r storage ponds be managed?

32

Irrigation Scheduling and Hydraulic Impacts

• W et weather storage ponds sho uld normalJy be dry! H as erosion abatement been designed properly?

• Ho w much automatio n is too much?

• H as the efil ue nt quality aspect allowed for com plications suc h as grease, gums, fi ne clay?

The main problem seems to be a lac k of com mun ication or int egra t ion between the diffe re nt gro ups or indi viduals carrying o ut differe nt sectio ns of these studies (such as hyd ra ulic balance or water budgeting, irrigation design, and the management recommendations) .

A hypothetical example would be: a) A hydraulic balance is prepared on a standard 20/30111111 soil moistu re deficit basis (or based on the EPA guideli nes), by one group or sec tion . b) A separate group or section then produ ces an irrigation design, w hich, from an irrigatio n point of view, seems feas ible, however it uses travelling irrigators applying 70mm each wate ri ng. c) During the discussion secti on o n the system managem ent, it is reconrn1ended that irrigation occurs only at night.

This lack of integrated design can have major impacts on the systems via bility. If the irrigati on system is design ed to appl y 70111111 each irrigati o n then the hydraulic balance should have been calculated on a 70/80 basis, not a 20/30111111 basis. The area and storage volume require ments wo uld need to be significantly higher and if a 70/80 irrigation schedule were used on a 20/30 designed system, then it would be grossly overloaded and would not be sustainable. Irrigation on ly at ni ght w ill more tha n dou ble the requ ired system capacity and increase area and/ or storage volume.

WATER SEPTEMBER/OCTOBER 2000

It is now comm on to base the hydraulic sizin g and design of wastewater sc hem es on a daily water balance w ith a soil m oistu re deficit t ri gger p o in t. Mo st models com mon ly use a 20/30mn1 strategy.

In simpl e terms this means that 20 mm o f irri gatio n sh o uld be applied when th e soil has dried out sufficiently and has a capacity to absorb 30111111 of moisture, leaving a deficit of 10111111 to absorb the first rainfall and surface nutrients follo w ing a rainfa ll eve n t th us min i misi ng the quantity and en hancing the quality of runoff Over recent yea rs, we have worked to explore th e practica l impl ication s of vary ing the trigger deficit p oin ts in line w ith the ca pabi li ties of specific irrigation eq uipm ent. T able 1 .is based on an operation in central western NSW which deals w ith an average of 762K L/day of hi gh strength efilu ent. Irrigatio n is o n a mix of red bro wn soils common to the area .

As can be see n fro m the table, the impact of an irrigation system realistically capable of frequent low applications of 5mm compared to one designed to apply 70111111 is considerable . If the hydraulic balance had been calculated on either a 5/15 or 20/30 trigger de fici t and then the irrigation had been designed around 70mm appli cations, th e results would have been disastrous. Com mun ication and co ordination between tea ms or individuals wo rking on hydraulic balances and irrigation design etc is essenti al.

Night-Only Irrigation

A statement such as "To minimise publ ic concern , irri gati on should be conducted at night onl y" seems reasonable. However, if irrigation hours are halved by restricting daylight irrigation, then the irrigation area, storage volume and irrigati on system capac ity w ill have to be increased.

In order to maximise the re use every advan tage sho uld be taken , incl ud in g maximising the evaporation losses, wh ich can be ve ry sign ifica nt if irrigation equipm ent is ca refu ll y selected and designed.

Night-time irrigation reduces this evaporation fro m operating irrigation syste ms.

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WASTEWATER

Table 1. Effect of varying soil moisture deficit trigger points Irrigation Strategy

70/80 20/30 5/15

Irrigation Area (Ha)

Storage Volume (ML)

Reuse Percentage

41.7 70 41.7 70

System overload

65 94

41 .7

128 128

70

110

Managed Waste Water Reuse Vs Farmer Use

W aste-water reuse and co nventional irriga tio n fa rming are worlds apart and are o ften in conflict.

T he aim of a designed waste-water reuse system is to utilise maximum wastewater with balanced optimised levels of nu trient rem oval and export, in a long term en viro nmentally accepta ble and sustainable manner. The body generating the efflu ent, w hether a co uncil sewage treatment plant, an abattoir, a starch plant, paper mill or the like, needs to retain a high level of co ntrol o ver the operation of such a schem e, to ensure that its obligations and responsibiliti es under its EPA li cence are maintained.

W e often refer to waste-water reuse as " Farming Backwards" as you aim to maximise irrigation losses (ie waste the water through evaporation as well as evapo-transpiration) and maximise nutrient rem oval by growing crops, i. e by raping th e soil of nutrients, both of which are against good fa rm manageme nt practice.

A fa rmer's main aim is to maximise his pro d uc ti o n , wh e th e r from g ra zin g animals, crops o r pastures for fo dder, against the time and dollar costs o f labo ur and energy . With crops and pasture growing well, why would a farm er need or want to expand time and m oney to start irrigating unless it was going to show a significant addition to the bottom lin e of his in come?

As an exa mpl e, we approached one of the m ost progressive dairy fa rmers in th e Shoalhaven area of N SW. H e utilises some of the efflu ent fro m th e Nowra STP fo r irrigation to m aximise his production .

By discussion and working thro ugh his electricity accounts it was established that fro m J uly 1 1996 to Ju ne 30 1997 he irriga ted fo r some 1104 ho urs or 46 days.

This is co nt rasted to the Mani ldra Groups, Shoalha ven Starches p lant, waste water reuse farm (only some 5km away) who irrigated 297 days over th e same p eriod, due to the differen t aims of the two operatio ns. â&#x20AC;˘ The time, labour and energy cost o f irrigating restrict the viability o f irrigatin g in m oist conditi o ns.

34

270 142

94 94 94 94

â&#x20AC;˘ In a high rain fa!J area, if the dairy fa rme r irrigated too mu ch and rain fo llowed , the gro un d w ould quickly saturate and there would be nowhere to graze the cows w ithout serious bogging and pugging, w hich effects milk produ ctio n and destroys the pastu res .

Th e ratio of reuse via the two types o f managem ent will decrease as you move inland to lower rainfall areas, where irrigation water has a greater importance and value placed on it. How ever, there will still be a marked difference between the levels of reuse achieved. Few farmers can see any eco nomical sense in watering during winter. lf supplementary irrigation is to be accommo dated then the effects must be factored into hydraul ic modelling and will result in a signi ficant increase in th e area and or storage volume req uired and hence require considerabl y more capital inves tment. The impact between the two m ay be likened to the difference between the 5/ 15 w aterin g strategy co mpa red to the 70/80 discussed earlier (see Tabl e 1).

Full Contract Management

T h e full contract ma na gem ent o f waste-water reuse proj ects by experienced and suitably qualified persons or companies is an optio n worthy of consideration. Depending on the scale of the proj ec t either a full or part time working manager would be placed on the project by the contractor with an experien ced and m ore senior person overseeing the managem ent and m onitoring work.

For a contra ct fee, the managin g company w ould operate the reuse fa rm using contractors for major farm op eratio ns such as culti va tio n, seeding and hay and/ or silage m aking, and would carry out the day-to-day operation and maintenance o f the irrigation including the daily record keeping and monito ring requ ired by the EPA licence . A special fee stru cture may be included in the contract as an incenti ve to ma ximise the reuse and share in the environmenta l resp onsibility.

The income from the sales o f fodder produ ced (or produ cts from other enterprises) would usually be directed to th e effluent generating company to off-sec the operation and managem ent costs.

WATER SEPTEMBER/OCTOBER 2000

Maximum reuse will not usually be ach ieved if the seemingly soft option of leasing or agistment agreem ents with local fa rmers is adopted.

Irrigation System Capacity

A waste-water reuse irrigation system must have sufficient capacity (ie litres/ second irrigated) to irriga te the average daily flo w as well as draw a signifi cant amo unt fro m storage to enable the storage to be emptied and take m aximum advantage of each hour of available irrigation tim e. 1 have seen a feasibility study of a proposed waste water system that only had th e capac ity o f the daily flow.

What happens to stored efflu ent?

T h e id ea l vi ab le c ap ac i ty li es som ewhere between th e average daily flow o f efflu ent generated , and the peak water requirem ent o f the particular crop under the specific site conditions, and would normally be at least twice the average daily effluen t flow .

If you apply the foll o wing rationale, ie there are only so many days per year availabl e for irrigation , and you have an annual ave rage vo lume of generated effluent to reuse (ie average daily x 365) then your irrigation capacity muse be mo re than sufficient to irrigate this annual volume in the ava ilable days suited to irri ga tion (ie daily flo ws and storage).

Ho wever, in o rder to p rovid e a m argin (all owing for unpredicted wet weather ingress, carry o ver storage, lost irrigation due to shift changes, breakdowns, delays in fo dder harvesting and o ther managem en t problems) and to ensure that the ponds can be clea red ready for winter I believe you should design with a capacity well in excess of this figure and believe it should be in th e order of 1.5 to 2 times the calculated figure.

Further modellin g has established chat 2 to 3 times th e ADWF is necessary depending on climate .

This capacity bec omes very important when you have a high volume o f storage relative to your irrigatio n area (say m ore than 100 days storage) and should see the full storage pond capacity cleared in 50 80 days o f irrigation. If this is no t the case than th e hydraulic balance should be carefull y reviewed.

Managing Volumes in Storage

Althou gh it is tempting to look at a large storage po nd with the attitude th at " th ere is plenty of capacity and it w ill never fi ll up" and th en decide to have a few days o ff fro m irrigatio n here and th ere and "just put it into storage", th is practice will somewh ere down the track lead to problems with possible enviro nmental consequ ences (including storage pond o ver topping and ex cessive irriga-

WASTEWATER

tion to try to avoid overtopping) .

M any designers of waste-water reuse system s seem to have a vision of storage ponds "near full" with du cks paddling on top and fish swimmin g below . This is NOT SO for wet weather storage ponds as they shou ld be dry and empty as much as possible, and chis facto r requi res good man agement.

An ope rato r (and desig ner) mu st understand chat every opportun ity fo r irrigation must be taken to maximise the volume reused and minimise the volume in storage. T here will undoubtedly be som e unplanned loss of irrigation time which is hard enough to make up.

In most areas of Southern Australia (Tropical Australia differs as winters are usu al.ly dri er and summ ers wetter) there will be less irrigation opportunity in winter so it is normal for most storages co hold a reasonable volume at the end of winter.

Th e aim should be to have your storages predominantl y empty prior to C hristmas. It may be reasonable to ease irrigation if your storages are below 20% fu ll by November to try to best distribute the waste-water over summ er to maintain vegetation cover. Howeve r, the aim is to have empty storages by February/M arch co prepare fo r winter.

Wh en designing erosion abatement on storage ponds, the fact that th ey will be emp ty mu ch of the time should be considered. I have seen several ponds with erosion control around top water level, and nothin g m ore. This is totally impractical fo r waste-water wee weath er sto rage pon ds.

Treatment Ponds are not Storages

Treatm ent ponds such as anaerobic ponds, aeration pond, maturation ponds etc are part of the treatm ent process and are usually maintained at constant levels using ove rflows. These ponds should not be considered as wee weather storage volume when calculating a hydraulic balance! As they will normally never be empty (unless cleaning out) and cannot accept extra volume in wee weather they are no t part of the wee weather storage equation.

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Although the latest technology in wea ther, soil moistu re, ground water mon itoring and satellite positioning etc are valuable management and m onitoring tools, too much reliance ca n be afforded to such automation with waste-wa ter irrigatio n. Waste-water projects cannot be effe ctively run from a control room and muddy boots are an essential part of a well operated and monitored proj ec t.

B asic irrigation automation and safety controls are essential, however, daily infie ld inspec tions are required to full y assess

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WATER SEPTEMBER/OCTOBER 2000

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WASTEWATER

moisture condi tions (portable moisture probes etc may be used if required) as we!J as crop conditions, growth stage, insect pest populations, weed co mpetition etc. Irrigation equipment also needs regular insp ection to ensure it is operating to maximum efficiency (eg blocked nozzles etc). This is especially important with under-tree sprinklers as a ruptured submain would not usually trigger a low pressure shut down , and if not located promptly co uld cause runoff.

With larger scale projects using larger irrigators such as pivots of, say, 100ha, even a large number of m oisture readings will not usually present a true picture of paddock condi tions, so regular fi eld inspection is essential.

Often the reliance on the automation (ie. infrequent field inspections) have caused problems of env ironmental concern.

Effluent Quality The nature of the eillu ent can also have a signifi cant impact on the practical operation of a waste- water reuse project.

EPA guid elines address factors such as nutrient levels, sa linity levels, h ydrau li c loadings, BOD etc but the actual nature of the eilluent is not usually addressed.

The following factors need consideration: • Grease levels , w hich lead to fouling of soil porosity and impeding of infiltration (from abattoirs, dairy factories etc) .

• Sticky gums causing surface sealing and dramatically effecting infiltration and evaporatio n (from starc h and foo d processing plants).

• Fine suspended clay particles fo ulin g soil porosity impeding soil drainage.

• A lgal growth (alive and decaying) causing odour and filtration problems (especially with d rip or m icrosp ray irrigation).

Although an experienced manager can work around such probl e ms (with practices such as frequent low applications of irrigation and regular surface soil aeration) they do dramatically effect the systems ability to utilise the e illuent load and allowance should be factored into hydraulic modelling and balance studies.

ti on strategy allows a manager to better farm the top 20cm of soil which helps mi nimise the nutrient percolation issues.

Another aspect of frequent low applications is the labour cost of achieving it.

T his aspect has been modelled (Murtagh 1996) and the extra cost of labour and energy hig hligh ted. H owever, these cost impacts are directly related to the irrigation type utilised. It is, for example, very difficult and extremely labour inte nsive to apply less than 20mm each irrigation with travelling irrigators, or 75mm w ith flood irrigation and tota!Jy impractical to irrigate less than these rates with this equipment.

On the other hand, correctly designed and set-up pivot irrigation (ie specifically for waste-water) is practically capable of these low applications (say 5mm each rotation) and economic on both labour and energy terms as it vircua!Jy costs no more to operate a pivot whether applying 5, 50 or 100mm each rotation.

Although pivots do not suit all locations they are fast becoming the standard for waste-water reuse .

Frequent Low Irrigation Applications

As shown above, major advantages lie in the adoption of more frequent lowe r irrigation applications (ie the 5/ 15 strategy in Table 1) both from an irrigation area vs storage perspective and also from a practical in-field operation perspective.

H owever, due to its benefits more waste-water wi!J usually be applied to each hectare and the implications of increased percolation need to be considered in nutrient balancing.

From a practica l viewpoint this irriga-

36

WATER SEPTEMBER/OCTOB ER 2000

Conclusion Issues including irrigation design , day and/or night operation, level and type of management planned, irrigation system capacity and the degree of au tomation must a!J be considered and factored into hydraulic modelling and feas ibility assessment in o rder to ensu re that proposed projects are practical to implement and realistic to operate, providing long term sustainable outcomes.

References Murtagh GJ (1996) Differences in strategies for effiuent reuse and production irrigation of crops.

NSW EPA draft guidelines "The utilisation of treated effluent by irrigation" February 1995.

Authors Allan

Murphy 1s Manager, E n viromnental Services, for Hassall & Associates , PO Box 1170, Dubbo, NSW 2830 and specialises in setting up wastewater irrigation schemes. Email amurphy@ hassall.com.au. Dr J Murtagh is a consu ltant in agricultural water management.

Email: lansci@ turboweb.net.au

WASTEWATER

FROM PROBLEM TO PROFIT: Wastewater Reclamation and Reuse on the Northern Adelaide Plains J Kelly and D Stevens Abstract

discharge to marine environments and an alternate method of disposal, or much higher quality and prohibitively expensive treatment, was required.

This paper describes a major scheme which has turned an environm ental problem into an economic success. Huge areas of horticultural produce on the North ern Adelaide Plains, SA, are irrigated with Class A reclaimed water fron1. Adelaide's maj or wastewater treatment plant through a 100 km pressu re reticulation scheme, thereby utilising the water profitably and reducing discharge of efiluent to the sea.

The Reclamation Scheme

Introduction The Northern Adelaide Plains (NAP), a horticultural region 30 km north of Adelaide has been described as the 'Vegie Bowl' of South Australia . It has 1200 growers (pers. comm . C raig Feutrill), with an estimated annual turn over in fresh and processed horticultural products of $160 million (pers. comm. Venton Cook), supplying produce to local, interstate and international markets. Further development and ongoing sustainability horticultural use of the area has been hampered by the availability of suitable quality grou ndwater for irrigation. For the past 28 years, in order to overcome water limitations some growers have irrigated with water sourced from the Bolivar Sewage Trea t men t Plant o utflow channel. This water was secondary treated efflu ent of Class D (An on, 1999a), suitable for restricted crop irrigation. Recently a high quality water reclamation and reticulation scheme has been co mmissioned to sup pl y ove r 200 growers with reclaimed water of Class A, sui table for unrestricted crop irrigation (Ano n , 1999a; H uijbregsen et al, 1999).

Several agronomic and environmental issues that relate to the scheme are briefly su mmarised below.

The Driving Force Behind Implementation of the Reclamation Scheme Two main forces have driven the reclaimed water project o n the NAP. These are the demand fo r an alternative water source of suitable quality for horticul tural irrigation o n the NAP and the

environmental degradation caused by dumping our wastewater into Gulf St. Vincent (Huijbregsen et al, 1999) . At the current rate of use grou ndwater on the NAP is being mined, with a drawdown of 28 GL/yr and an annual replenishment estimated to be between 6-10 GL/yr (Anon, 1996). The over use of groundwater on the NAP has seen a decline in water quality to the extent in some areas that ground water is now unsuitable for irrigation of horticultural crops. Prior to the commissioning of the reclamation scheme (described below) Bolivar Sewage Treatment Plant was discharging 40-50 GL/y into the ocean.

The re is strong evid en ce that this discharge has been a major contributor to destruction of hundreds of hectares of sea grass and mangroves (Anon, 1996; Huijbregsen et al, 1999). South A u stralian Gove rnment policy is designed to restrict sewage effluent

T he Bolivar Sewage Treatment Plant is Adelaide's major efiluent treatment plant with the capability to produce an outflow of 135 ML/day (Marks et al., 1998). The Bolivar/NAP water reclamation project is the largest high quality reclaimed water scheme in Australia (Marks et al., 1998). South Australia (SA) Water has built a tertiary treatment plant, which uses Dissolved Air Flotation and Filtration (DAFF) and disinfecti on by chlorination to provide C lass A Reclaimed Water (Anon, 1999a). Water produced by the DAFF plant mee ts some of the most stringent Australian and In ternational guid elines an d is suitabl e for unrestricted use for agricultural irrigation (as classified by the SA D epartment of Human Services and EPA), in pa rticular for unrestricted spray irrigation on all frui t and vegetables including leafy salad lines (Anon, 1999a).

Euratech Limited has laid some 100 km of pressure piping to reticulate this water to horticulturists on the NAP. The scheme has the capabili ty to supply up to 30 GL/annum to over 200 su bscribers/growers. This project has cost investors $45 million and was finis hed in late 1999 (Wright, 2000).

The reclaimed water reticulation scheme was commissioned to provide customers w ith a minimum daily flow rate equal to 0.54% of their annual allocation. Water Reticulation Systems Virginia Pty Ltd

Table 1 Bolivar reclaimed water rates per KL Spring

Summer

Autumn

Winter

Initi al contracts

$0.075

$0.090

$0.075

$0.050

Later cont racts <20 ML 20-49M 50-100M

$0.195 $0.152

$0.283 $0.222

$0.177

$0.124

$0.230

$0.138

$0.097

$0.180

$0.127

$0.185

>100M

$0.110

$0.160

$0.115 $0.100

$0.081 $0.070

$0.150 $0.130

Flat rate

WATER SEPTEMBER/OCTOBER 200 0

37

WASTEWATER

Table 2. Water Qualit y of Class A and D Reclaimed Water and a major aquifer used for irrigation on the Northern Adelaide Plains .

Parameter pH na TDS (mg/L)

CDRW

CDRW

CARW

T2 Aquife r

1975-1978

1994-1997

9/ 1999-4/ 2000

1999

na

7.0±0.2 1215±87 2.1±0.2

1 217±1 25

1345±111 2.4±0.2 na na na 10.7±1.2

EC (dS/m) TKN (mg/L) Total P (mg/ L) E. col i (1100ml) SAR Cl (mg/L) Cd (mg/L)

na na na 8.5±0.6

na na

na na

7.7±0.1 2.0±0.2 1 5.5±10.3 0.7±0.5 2.9±3.0 8.4±0.3 407±39 <0.0002

985±314 1.8±0.6 <0.2 <0.005 na 6.8±2.2 389±162 <0.0002

T2 Aquifer (Stevens et al., 2000a). CARW = Class A Reclaimed Water produced by DAFF plant (WRSV). CDRW = Class D Reclaimed Water (SA Water). TKN = Total Kjeldahl Nitrogen. na = not available. SAR = Sodium absorption ratio. Error± one standard deviation from the mean.

(WRSY) m anages th e pipeline and the su pply of reclaimed water to g rowers.

WR.SY mu st al so co mply with th e V irginia Pip e lin e Sc h e m e Irri gation Management Plan as comm issioned b y the SA Gov e rnm e nt to c r ea t e a co mm ercial viable and eco logi c ally susta inable schem e (Anon, 19996) .

farm storage for two main reasons. Firstly, to supply a b reak in the supply chain to prevent bac k flu shes into th e primary distribution network. Secondly, in the event o f major problems with the DAFF plant, on -fa rm storage must have the capacity to store a minimum vo lume equivalent to 1 da y at the guaranteed supply rate . WRSV recommen d that R eclaimed water supply contracts with growers w ith bore water backup install an WR.SY requ ired that g rowe rs build o non-fa r m st orage fac ility equal to 3 days at the gu arant e ed supp ly rate "TODAYS' TfCHNOLOGY PROTfCT/NG TOMORROWS' fNV!RONMfNr' and 7 da ys for those without bore back u p (A n o n , 1998) . D epending on the irrigatio n systems used and area irrigated there are al so o th e r agronomic considerations for t h e d esign of on-farm storage fac ilit ies.

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South Australian Water has set onfarm p rices for th e reclaimed w ater, as s ummari sed 111 Table 1.

Agronomic Research Three ex tensive studies covering all areas of th e reclam ation and reuse sc h e me we r e co mple ted befo re th e sc h e m e was app roved (Hod gson, ·1966; Anon,

1976; Anon, 1995). Additi o nal studi es to assess the s h ort and lo n g-te rm agronomic m anagement of the reclaimed water to ensu re it is sustainable are cu rre ntly be ing co nducted by th e University of Adelaide/CS IRO Land and Water and Primary Indu stry and R esources South Au stra li a (PIRSA) R.ural Solutions. T hese research proj ects a r e fund e d b y th e H o rt i cul tur a l R esearc h and D evelopment Corporation (HRDC) and the National H eritage T ru st / Landcare, respec tively .

Some g ro wers have used class D reclaimed water for up to 28 yea rs and th is has provid ed researche rs w ith an opportu n ity to study th e long -term effects of irrigatio n w ith this c lass o f reclaimed water. C lass A recla ime d water now available to g rowers on the NAP is of a sli g htly better quality chemi cally for irrigation pu rposes than th e class D reclaimed water initiall y used (T able 2), and of muc h highe r microbial quality than the Class D re claim ed water previo usly used (Table 2).

R esea rc h by t h e University of Adelaide/CS!RO Land and Water has focused in pa r t on th e ch anges in physico-chem ical p roperties o f soils fro m irri ga tion wi th reclaimed water. Paired so il sa mpl es we re ta ken fr o m sit es irrigated w ith class D reclaim ed w ate r, bore wa te r and soils no t irrigated and used to assess p h ysico-chemi cal c han ges from irrig atio n w ith re claimed water (Steve ns ct al., 20006). Other research assessed nutritional benefits of N and P contained in the wa ter; sodium and c h loride toxic i ty; mobili sation of ca dmi u m; so di c ity and sa linit y; pathogeni c contaminatio n o f produ ce; algae in o n-farm storage; and soil boron levels. A reference manual for using recla imed water o n the NAP is curren tly be in g compil ed to assist growe rs, horti c ultural advisors and co nsulta n ts in m anaging recla im ed water o n th e NA P. The paired site study has sho w n w hen using reclaimed water in the long- term ( 15-28 yea rs) there are in sig n ifican t c hanges in so il pH; sm all m easurable in creases in sodicity (S AR.) ; no measurable changes in so il sa linity; and so il boron levels ha ve increased , but not to p h y totoxic levels. Current m anagem ent practices, w h ich add calcium amendm e n ts to soils, shou ld maintain soil p h ysico-chemica l prop erties off-setting the sli ght sodic (increased SAR) effects of the reclaimed water. Good irrigati o n manag e m e nt s hou l d pr eve nt th e accum ulati on o f salts in surface soils.

Field tria l and marke t baske t surveys of pro du ce i ndic ated no in c r e a se in

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WASTEWATER

cadmium uptake by plants due to reclaimed water use. As expected, when using such high quality water, there has been no reported pathogenic contamination of produce from irrigation with reclaimed water. Several methods for controlling alga e have been assessed and further research is required to identify cost effective methods of algae control.

Further research is also required to better assess hydrological changes on the NAP .

Education and Adoption of Reclaimed Water T he success of the NAP reclaimed water project is underpinned by the successful adoption of class A reclaimed water and its use in the production of produce for human co nsumption. T o succeed produce must be accepted by the prod u cer and consumer.

Consequen tly, an important part of the research projects on the NAP has been extension to increase grower awareness by providing them with the facts abou t reclaimed water management. Similar to the M on terey Wastewater Reclamation St u dy we have a lso found that inn uendo, rumours and negative pub lic relations could be contained by the

disse m ination o f factual information (Asano, 1998).

A recl aimed water info rmation package was recently produced collaboratively between PIRSA, The University of Adelaide and CS IRO. The package addressed issues raised by growers and advisors, and con tained up -to-da t e research info rmation. The aims of the information package were to enable decisions to be made on scientific fact and not district gossip, and to prevent growers unknowingly producing crops of poor quality, inadvertently leading to bad public relations for reclaim ed water.

The information package covered several areas: controlling algae in farm dams; soils on the NAP and their intera ction with reclaimed water; saline and sodic soils; irrigation scheduling; cleaning irrigation e q u ipme nt ; c hlo r ide in reclaimed water; long-term effects of reclaim ed water on soils; managing cadmium concentrations in produce; water q uality; food quality; the environm ent. In addition to the information package, tra ining programs have been planned by PI RSA and the loca l Land Management Group for: soil testing and fertility; leaf analysis and plant n utrition; soil salinity; irrigation; best managem ent practice for soils and irrigation in horticulture.

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Problems with alga e growth in on-farm storage have bee n a major concern for some growers. Alga e can ca use blockage of irrigation e quipm e nt and potentially lower produce qual ity as a result of algae contamination . summer H ot periods, co mb i n ed with the nutrient loading of the Class A reclaimed wate r (Table 1) and the residence tim e of water in dams crea t e th e id ea l environment for algal blooms.

H owever, th ese problems are not co mpletely

isolated to reclaimed water alone and can be found, to a lesser extent, in som e bore water dams.

Major problems reported by users of reclaimed water this irrigation seaso n were associated with irrigation. Filters and micro/drip irrigation systems became clogged with algae, effecting irrigatio n efficiency an d distribution uniformity of water. T here have been no reported issues relating to produce quality and market rejection of produce due to contamination fro m algae contai ned in reclaimed water.

However, in so m e situations algae growth has increased in frastructure and maintenance costs.

Growing Horticult ural Crops: Some Case Studies Growers are cu rrently using class A reclaimed water on a large range of vegetables and irrigated horticultural crops, including some crops sensitive to salin e conditions (e.g. potatoes, vines and almonds). There have been isolated problems o f so il sa linity on crops irrigated with recla imed water. For example, after 25 years of reclaimed water use, one grower needed to use bore water late in the growin g season to overcome salinity stress on the crop. It is difficult to assess whether this salt stress was because of reclaimed water use, excessive fertil isation o r inadeq uate leac hing. Like any water so urces, class A reclaimed water needs to be assessed for its suitability fo r use with specifi c crops.

The adoption of good agronomic practice with effective leaching fra ctions and the maintenance o f soil structu re enables users to stop the accumulatio n of damaging sa lts in th e so il. Like any water source its quality m ust be matched with the soi ls and plants to be grown.

C lass A reclaim ed water has been approved for use in Certifi ed Organ ic production. What is believed to be one of the largest orga nically certifi ed horticultural properties in the Pacifi c regio n has been established on the NAP, with over 1338 ha avai lab le for o rgan ic production . T he company is certified by the Organic Food C hain Pty Ltd, an Australian Quarantine and Inspection Service (AQ IS) accredited organic certifying bod y . T he co mpa n y grows produce that is both organic and nongenetically modified . To date th ey ha ve produced potatoes, broccoli, ca rrots, lettuce, celery and ca uliflower irrigated Nutrie n ts w it h reclaimed water. contained in the water are seen as an advantage in the nutritional management of organically grown crops.

WASTEWATER

Conclusion T h e NAP water reclamation sc hem e has the potential co tu rn an environmental li ability into an economic success. Full scale long-term use of reclaimed water and im.pl em encacio n and adoption o f appropriate m an agem ent practi ces, cu rrentl y being developed by resea rch projects above, sho uld ensure this potential is met .

The Authors and Research Team Jim Kelly is a R esea rch Officer w ith the University of Ade laide, Department of Soil and Water (08 83037398), and Dr Daryl Stevens a R esea rch Scien tist with CS IRO Land and Water, Adelaide (P hone 08 83038533). T hi s work is funded by the H orticultu ral R esea rch and D evelopment Corporation . W e would also like to rec ogn ise th e scie ntifi c and techni cal ad vice and assista nce of Dr Mike Mclaughlin, Dr Gary Owens, Ms Michelle Smart and other casual workers who have made major contributions to th is research, and th e cooperation and support of th e growe rs on the NAP.

References A non ( 1976). Use of Boliva r effiu e nt for irrigat ion o n the N o rthern Adelaide Plains. Kinn aird H ill , de R.o han Yo ung Pry, Ltd .

Anon ( 1995). Virginia Pipeline Comm ittee. Bo li var - Virginia R..euse P roject. r~ogc rs Sto kes an d Associates in associat ion with Gutteridge Haskins & Davey Pty Ltd. Adelaide/M elbo urne .

Anon ( 1996). Virginia Pipeline Scheme T reated W at er Smdy Final l"l...eport. W ater D ivision o f Kinhill Engineers Pry. Ltd., Parkside, Adelaide.

Anon (1998). W ater - the profit opportunity, Virginia Pipelin e Scheme. W R.S(V), Virginia SA. Anon ( 1999a) . R eclaimed W ater G uidelines . Department o f Hu man Services and Environment Prot ection Agency, Govern m en t o f South Australia, Adelaide, South Australia.

Anon ( I 9996) . Virginia Pipel ine Sche me . Irrigation M anagem ent P lan . D epa rtm ent for Adm inistrative and Inform ation Services, SA Government, Adelaide.

An o n (1999c). Cost of algal blooms, Final 11,epo rc. l"l...ep. No. 26/99.

Land and Water l<.escarc h and D eve lopment Corporation , C anbe rra .

Asa n o T ( 1998). W ast ewater reclamation and reuse. Vol. JO, pp . 11528. Technomic Publishi n g Compan y, I nc., Lancaster, P e nnsylva nia, U SA. H odgson HJN ( 1966) l"l...eport of the Comm itt ee of Enquiry into t he Utili zation of Emucnt from Bo li var Sewage T reatment Works .

Adelaide: Sout h Australian Government Print er.

H uijbregsen C, Yerrcll K. Bashe r C, Sickerdick L ( 1999) Bo livar DAFF plant - Australia's largest reclaimed water t reatment plant.

Aust ral ian Water and Wastewater Association (A WWA) Inc. J 8th Federal Conventio n , Adelaide, A ustralia .

M arks I<., Wright C, Kracman B, Thomas R. ( 1998) D evelopm ent of A ust ralia's largest high quality effiuent reuse scheme - Boliva r, S.A. In I Ith IWSA-ASPAC R.egio nal Conferen ce. pp. 564- 570, Sydney.

Sheikh B, Cort R., Cooper l"l..C, J aques R.S (1998) Tert iary-Treated Reclaimed W ater fo r Irrigation of Raw-Eaten Vegetables in W astewater reclamation and re use . ed Asano T. Vol. I 0, pp. 1- 1528.

T ech no mic Publishi ng Company. Inc ., Lancaster, Pennsylvania, USA. Stevens, D. P. , L. Starcic. N . Gerges, Z. C h en , R.. Kookana, and M .

M cLa ughlin . (2000a). Aquifers o f the Northern Adelaide Plains. A water quality basel in e study. Adelaide, Australia. Northern Adelaide and tlarossa Water Catchment Manage ment Boa rd.

Stevens DP, M cLaughli n MJ , Smart MK (20006) Is lo ng-term reclaimed water use detrimental to soil ' Sou th Australia's experie n ce o n the Northern Adelaide Plains. Sub mitted NZSSS & ASSS C onfe rence, New Z eala nd.

Wright CA (2000) E xperience of distribution of grey wate r for u nrest ricted agriculmral use in Som h Australia. In Irrigat io n A sso c iation of A us tralia , 2000 National Co nfe rence and Exhibit ion. pp. 561-564. Irrigation Association of Australia, M elbourne.

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WASTEWATER

AUSTRALIA'S LARGEST WATER RE-USE PROJECTS B Ellis The North Adelaide Plains Project The "Virginia Irrigation" scheme, the largest water reuse system in the Southern H emisphere, took 20 years to initiate, 2 .5 years to negotiate and 18 months to construct . As described by Kelly & Stevens in this issue, It is a groundbreaking project for Australia.

The $22 million BOOT project is operated by Water Reticulation Systems Virginia (WRSV), a w holly owned company of Euratech Pty Ltd. WRSV will operate the scheme fo r a period of 20 years when it will be transferred to SA Water.

It delivers Class A standard trea ted water - an essentia l ingredient of the scheme as it allows unrestricted irrigatio n use.

To provide a buffer between th e treatment plant and the WRSV pump station a 10ML polybutylene lined dam was built, providing a 2 hour balancing storage at the sumn1.er peak demand of 11 0 MI/ day. The rema inder of the plant flow continues down the origi nal outfall channel to the sea.

A single pump station operates five Kelly and Lewis centrifugal pumps, each with a capacity of 3001/sec, powered by 250 kW motors operated with variable speed drives. A telemetry system continuously feeds back flows and pressures to the pump station's PLC. Pump speeds are adjusted to maintain the designated pressure. If a fault occurs the system dials out to an emergency response team.

The system consists of two distinct trunks, one supplying the channel north of the triangle the other the north east side to Angle Vale.

Two pumps provide flow to eac h main with one pump as a commo n spare . The maximum vertical lift of 35 metres occurs on the Angle Vale trun k.

The WRSV project incorporates a network of over 105 kilometres of ABS pipe supplied by Eurap ipe, part of the Euratech group, and lin ks over 230 horticultural properties in the Virginia Triangle. Pipe sizes range from 0 826 mm down to 0 100 111111 with pressure classes from PN4.5 up to PN6.5. T he

42

pipes were laid at a minimum depth of 750111111 and joined using solvent ceme nt weld ing or by rubber ring j o int.

Pipelaying was split in to 4 separate contracts each of 25 Kms. The sc hem e became operational in November 1999 in time fo r the summer growing season.

Melbourne's Eastern Treatment Plant Irrigation Scheme Looking to the future, Euratec h and Multiplex have formed the Aquaforte Joint Venture, and have completed the feasibility study for an irrigation scheme using water from M elbourne Water's Eastern Treatment Plant (ETP) at Carrum.

T he majority of the current outflow from this plant is pumped 56 km from Carrum to an outfall in to Bass Strait.

The Aquaforte study looked at the potential to take part of this flow and distribute 'A' grade treated water to horticultural custo mers in a region to the south east of ETP. The study is now with Melbourne Water for evaluation.

The feasibility stud y looked closely at a number of key issues: Water Treatment: Review of the current ETP water quality and the EPA 'Environmental Guideline for the use of Reclaimed Water 2000' : The treatment technologies required for me eting EPA and marketin g n ee ds: Th e relative capital and running costs of treatment.

Pipelines and distribution system: Design based on demand models and

WATER SEPTEMBER/OCTOBER 2000

market locations. Selection of routes to minimise pipelines to access ible demand, disruption to property and environment: Access for construction and maintenance: Capacity of the system to expand over the projected life.

Demand for water: Curren t supply situation (rainwater, bore water etc): Water qua lity: Ground water salinity and changin g weather patterns . Demand versus pricing and seasonal capacity.

Economics and fonding: T hese issues are the key to these schemes. Aquaforte JV have carried out an extensive study of sources of funding for capital investment, income, project structure and ownership (BOOT, BOT etc) and li fe of the sc heme.

Conclusions T he feasibility studies findings were very favorab le to the establishment of a financially viable scheme taking over 5GL per annum. Vital to the scheme is state government funding. H owever, the economic and env ironm ental benefits of the schem e proposed significantly outweigh these costs.

Author Bernard Ellis is Manager, Victoria, for Eurapipe Australia, a Division of Euratech. He is a mechanical engi neer with over 25 years' experience in pipes and pumping .

Email ellisb@ eu rap1pe.co111.au

WASTEWATER

GUIDELINES FOR WASTEWATER IRRIGATION R Standen Introduction R e nde ll M cG u c ki a n h a ve b ee n wo rkin g w i th th e V ic t o r i a n En viro nme nt Protection Auth o rity (Vi c EPA) to pro du ce t he Best Prac tice En viro nme n tal M anage m ent G uidelin es (l3 PEMG) fo r W astewater Irrigation, part ofa sui te ofBP EMG. Th e W astewater Irrigatio n BPEMG is sp ec i fi c all y a b o u t irri ga tion w ith w as t ew ate r a nd co mp le m e nts th e broader En viro nm ental G u ide lin es for the U se of R eclaimed W ater. T o ga in Vi c EPA approval fo r irrigating with w aste wate r, a propo ne nt mu st be able to d em o nstrate that t he o utcom es liste d in th e Wastewater Irri gation BPEM G can be ac hieved At th e time of pre paratio n of this pap e r, th e BPEMG fo r W as tewate r Irrigation was in draft fo rm . Du e to t his timing, the details in th e g uide lin es m ay

c hange sli ghtly. T h is pape r is to explain ho w to use th e m w hen they appear. T his paper is no t to be used , o r quo ted , as t he g uid elin es the m selves.

Approach to the Guidelines: Outcomes Focussed

ti o n has been de fi ned as th e need to : "u tilise th e available wastewater as a resource that is consiste nt w ith th e users busin ess o bj ectives a nd in a m anner th at is ecologically susta inable" .

So m e exa m p les o f p e r fo r man c e o u tcom es that ensure no ad verse impac t resulting from surfa ce water m o ve m ent are that

A cl ear foc us on the o utcom es to be ac hieved by using waste w ate r fo r irri gati o n was th e startin g po int in writing the • "wate r does not flow on to t he irrigag uidelin es. Identifying t he o ve rall o bj ec tive Table 1. Elements in sustainabl e wastewater irrigation and th en de fin ing t he Protection of Be neficial Use performance o utco m es Using Wastewat er that must be in pla ce to • wastewater volume • soil ac hi eve th e sustainable • nutrients • surface water irriga tion w ith w aste• sa lt and sodicity • groundwater wa ter we re the first • human and stock health • viability steps.

• public amenity • othe r toxicants The overall o bj ec• native veget ation t i ve w he n u sin g • cult ural heritage wastew ater fo r 1rn ga-

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Outcomes to be achieved through wastewater irrigation under 12 elements Nutrients

Volume of Wastewater

\ Viabilit y '

t

SalV Sodicity

I

Other Toxicants

Practices - determined by risk level

/

Irrigation System Site Treatment Water Irrigation Type +-Risks --+ Plant Type +-Risks --+ Management

Cultural Herita g e -

-

s oil

t

Nativ e / Vegetation Public / Amenity

Risks

~

,I.

+

Human & Stock Health

\

Surfac e Wat er

Groundwater

Figure 1. Irrigati on system pract ices, risks and performance outcomes

tion site causing a reduction in plant growth or irrigation water use" • off-site drainage does not contain any matter that adversely impacts o n the receiving water (or land) • applied wastewater m ust not d irectly enter drainage lines or waterco urses All people considering wastewater irrigation, those managing the irrigation and those responsible for monitoring and reviewing t he perfo rma nces of the irrigation system will need to understand how to achieve the outcomes in the guidelines.

Content of the Guidelines T he gu idelines have several sections that are listed here. Only the components of th e schemes and the elements contribu ting to the sustainable use of the wastewater are discussed in this paper.

The sections to be included in the guidelines are: • the statu tory framework fo r irrigating w ith wastewater • principles of wastewater irrigation • components of wastewater irrigation sch emes • the elements contributing to sustainable wastewater irrigation that include: - the performance outcomes for each element - issues relating to that element - the situations leading to differe nt risk levels - practices to use (dependent on risk level) and - a monitoring and review process • enviro n me n tal improvem en t plan framework • a check.list • roles and responsibilities

44

Components of Wastewater Irrigation Systems There are five main components of an irrigation system . T he five components are: • treated water (water quality) • site • plant type • irrigation type • management Each of t h ese compone nt s 1s described, including some exam ples of the suitability of diffe rent situations to use wastewater for irrigation and some of the issues involved in assessing the situation. An outline of options is given for each compo n en t , w h ere th ese options are best suited, w here they are not suited and w hat the bounda ries are .

Elements Contributing to Sustainable Wastewater Irrigation Twelve elements w ill be described in the guidelines and they all need to be considered when developing appropriate management practices for irrigating with wastewater.

T hese elements are listed in Table 1 in two groups. The first five relate to using wastewater (operator foc ussed) and the next seven are about protecting the beneficial use. Each element has its own set of performance outcomes that are needed to achieve the overall objective for wastewater irrigation.

To use the guidelines, the foJlowing steps are advised: • check each element • recognise the desired outcome • determine the risk level associated w ith the element

WATER SEPTEMBER/ OCTOBER 2000

• select an approp ria t e action (or practice) to achieve the outcome, given the existing risk level.

T he situation that exists for each compo nent of the irrigation system determines the risk level for irrigating w ith wastewater. T hese risk levels (high or low) lead to the selection of the most appropriate practice that will achieve the relevant pe1formance outcome.

T his process is repeated for each of the twelve elements. As practices impact on several elements, practices (for a given risk level) that are selected to meet a performance outcome fo r one element will impact on the capaciry to achieve performance o ut comes in another element.

Each element can be worked through in turn, but the requirement to meet all outcomes means there is interaction between the elements. T herefore an iterative approach is needed to develop the final set of practices fo r the irrigation and land use system .

H ow the components of the irrigation system come together and relate to the performance outcomes that m ust be achieved when irrigating with wastewater, is shown in Figure 1.

Conclusion T h e B PEMG for Wastewater Irrigation has been written w ith a focus on clearly understanding the ou tcomes to be achieved for sustainable irrigation w ith wastewater. T his is supported with explanations of risks and what constitutes high and low risk levels that lead the operators and managers to the most appropriate practices.

Previously wastewater practice guidelines have had less foc u s on r isk management. T hese guidelines address that deficiency, will be robust, but can be flex ible in determining how each of the requ ired outcomes is achieved.

Al] Victorian producers and users of wastewater for irrigation should get a copy of t h e n ew BPEMG for Wastewater Irrigation when they are completed .

Author Roger Standell is an Agricul tural Scientist with twenty years experience in irrigation and natural resource management and is a Principal Consultant with Rendell M cGuckian, Agricultural and Ma n agemen t Co nsu ltants, Be nd igo.

Phone:(03) 5441 4821 Email rogers@ rendellmcguckian.com.au

WASTEWATER

Abstract Irriga tion with recycled eilluent ca n be an effective economic and environm entally sound solution to upgrading wastewa ter treatment plants . However a number of issues in relation to management of the irrigation site must be addressed . This includes initial assessment of effiuent quality, soils and appropriate wa ter and nutrient balances. Sodium salts in effiuent can also lead to sodicity, which over a period of yea rs can result in maj o r loss of soil stru cture and consequent poor plant growth. Sodicity therefore needs to be assessed over the long term . Appropri ate indu strial waste policies to minimise sodium should be int roduced an d fa rm m anage m e nt practices altered to minimise the sodicity risk. Long term monitoring of the soil needs to be carried out to assess the effectiveness of these managem ent ac tions.

Introduction Effiuent irriga tion is w idely prac ticed in northern Victoria, being the preferred requirem ent in the State Environment Pro tection Policy - W aters of Victoria.

The Victorian Environment Protection Authority (EPA) also actively promotes irrigatio n as a re-use option. As a consequence there is an increasing number of Victorian wa ter authorities adop ting this practice.

Effiuent irrigation has a number of advantages, as well as disadvantages .

Secondary level treatment is generally sufficient for common irriga ti on re-use requirem ents, leading to potential savings in treatment costs w hen compared to tertiary treatment plants required for discharge to receiving waters . Depending on land pri ces or land irrigation arrangements, the cost for re-use onto land is also moderate.

However, before adopting land base re-use, it is imperative that water authorities have a good understanding of the charac teristics of their soils and effiuents to ensure long term sustainability of the re-use system.

In various EPA guidebooks (EPA 1991, EPA 1996), the issues of water and nu trien t balances are addressed at length.

M anagement and regulatory authorities generally have a reasonable appreciation of the requirements for balancing these materials. However few wa ter authorities, regulatory agencies or consultants understand the longer term threat of soil sodification . It is only som e years down the track, when soil problems arise, that the water authority comes looking for answers. There is a particular risk as relatively few effiuent re-use schem es on sensitive soils have been in operation for lengthy periods.

Like many water authorities, Goulburn Valley W ater has a number of wastewater p lants situ ated on n onoptimal irriga tion land, many containing soils with a high clay content. These are

precisely the soils that are at th e m ost risk of sodificatio n. As a co n se qu e n ce, Go ulburn Va ll ey Water h as b ee n working w ith Agric ultu re Victoria T atura for a number of yea rs to identify the risks to its land based sites, monitor changes in soils and to implem ent appropriate management practices.

This paper outlines som e of the issues encountered by Go ulburn Valley Water, reviews some long term monitoring and discusses management arrangem ents to mitigate future problems with sustainability. The threat of soil sodification is specifically addressed.

Effluent and Soil Quality on Goulburn Valley Water Sites Go ulburn Valley Wa ter's strategic direction is to maximise land based reuse of effiuent. At present, Go ulburn Valley Water operates 25 was tewater treatment plants in central Victoria, of which 21 practice full irrigation and 3 partially irrigate. The largest facility, Shepparton, now has some 400ha under irrigatio n. Our assessment indicates the capital cost of development and the ongoing operational costs are significa ntly lower in mo st ' cases when compared to full tertiary treatment.

The range of plants grow n a t Go ulbu rn Valley Water sites includes perennial pasture (ryegrass/ clover), crops (m aize, oats, lucerne, barley, sunflower) as well as a variety of tree species includ-

WATER SEPTEMBER/ OCTOBER 2000

45

WASTEWATER

Table 1. Effl uent Quality at Se lected Goul b urn Vall ey Water STP Sites Units

Euroa

8.3

8.5

9.1

8.7

8.4

8.8

8.5

9.0

8.0

uS/cm

855

766

832

1,904

417

1,233

1,454

2,937

1,850

Total Dissolved Sol ids (Gravimetric)

mg/ L

506

524

460

1 ,084

370

848

848

1 ,690

1,080

Sodium Adsorption Ratio (SAR)

me/ L

4.9

6 .7

9.0

7.2

3.6

11.0

5.1

18.3

9 .1

Biochemica l Oxygen Demand (5 day)

mg/L

18

68

53

64

28

54

70

99

300

Fi ltered BOD5

mg/ L

8

21

20

16

10

13

16

26

87

Suspended Solids

mg/ L

23

60

115

95

51

65

94

169

190

Total Kje ldah l Nitrogen

mg/ L

6 .9

9.0

12.9

23.1

4.9

14.7

15 .2

25.8

54.8

Ammonia

mg/ L

3.2

2 .9

8.4

10.4

3.6

2.6

3.6

26.2

Nitrate

mg/ L

0.8

1 .6

0.2

0.4

3.1

1.6

1 .5

1.2

6.8

Total Phosphorus

mg/ L

7.1

11.9

4 .7

5.8

3.1

3.5

3.5

5 .9

26 .0

pH Elect rica l Conductivity

Kyabram

Nathalia

Nagambie

Numurkah

Shepparton Tatura (1 > Tongala (2 )

Cobram

(1 ) Tatura Effluent is shandied 2 .5 to 3:1 with freshwater (200uS/ cm EC) (2) Tonga/a Effluent is shandied 1:1 with freshwater (200uS/ cm EC)

ing eucalypts and casuarinas.

The qu ality of eillu ent used for irrigatio n va ries as do the soils under irrigati o n. T ables l and 2 provide an indicatio n of m ean eillu ent and soil qualities at selec ted w as te water treatment plant (WWTP) sites, respecti vely.

The maj o ri ty of the soils in th e table are the heavier clays o r clay loams, however the N athalia and Euroa sites ha ve sandy loam soils.

Water Budget s It is obviously impo rtant to match wa ter need to a plant's requirements.

This water requirement va ries in differ-

ing cbmates and also depends on the p a rti c ul ar pl a nt und e r irri ga tion.

Guidelines (EPA 199 1) can assist in calcul ating water demand.

In Goulburn Valley Water northern plants (Shepparton Region) for perennial pas ture productio n, approxim ately 8001000111111 of wa ter is required per annum (8- l 0M L/ ha) . In areas so uth of the Divide (Seym o ur R egio n), this requirem e nt drop s to 40 0-600 mm (4 6ML/ ha/ annum).

O ve r- irriga ti o n ma y res ult w hen th ere is in adequ ate efflu ent storage ca pacity or too little land. This may kill pasture and will ultimately damage soils

leadin g to problems of salinity, sodicity a nd c ontamin a t e d g round wa t e r .

Appropriate water budgets are therefore important.

Nit rogen and Phosphorus EPA has promoted a nitrogen and phospho rus balance as being essential to sustain able irri gatio n . T hat is, the applied nitrogen and phosphoru s should match the nitroge n and phosphorus utili sed by the plant. EPA often requires these nutri ent balances to be calculated and adh ered to .

For no rmal levels of phospho rus and nitro ge n in seco ndary e fflu ent (8-

Table 2. Soi l Chem istry Resu lts f rom se lect ed Gou lburn Va ll ey Wat er WWTP sites (Mean values f rom a number of topsoi l samp les, 0 -0 .2m) Parameter

Unit

Cobram (18)

Euroa (25)

Kyabram (1 7)

Nagambi e (6 )

Nath alia (21)

Numurkah ( 27 )

Shepparton (1 0)

Tatura (0)

7.2

5.8

6 .5

6.2

5 .6

7.4

8.0

6.0

6.5

dS/ m

0.23

0 .08

0.08

0 .19

0.24

0.29

0.45

0 .23

0 .70

Bicarbonate

mg/ kg

1140

145

353

200

1570

1150

187

388

Olsen P

mg/ kg

38 .5

38.2

15 .8

3.5

78.8

8.9

15 .3

11.0

24.2

Total Kj eldahl Nitroge n

%

0.13

0.07

0.19

0.11

0.19

0 .09

3.8

0.14

0.18

Oxidisab le Organ ic Carbon

%

1.36

0.81

0 .96

0 .75

1.60

0.90

1.23

1.46

1 .17

Clay Dispersion

%

7.4

4.7

7.1

9.0

5.7

7 .4

7.3

11 .0

4.2

Total Cation Concentration

meq / L

9.1

1 .3

2.4

3.1

2.7

13.6

7.7

Ch loride

meq/ kg

81.9

30 .1

13.1

57.7

92.8

128

198

229

314

pH (CaCl 2 ) EC1,s

Tongala (1 7)

6.4

Exc h. Ca lcium

meq/ kg

65 .7

12.7

27 .2

26.7

28.5

69.3

45.9

32.4

55

Exch. Potassium

meq/ kg

7.2

2.2

4.2

3.3

7.8

7.4

8.5

5.9

10.7

Exch . Magnesium

meq/ kg

73.2

11.9

35

26.8

27.9

58 .2

33.7

32.3

72.5

meq/ kg

33 .

3.6

2.3

8.9

7.8

42 .1

17.7

6 .9 ,

28.4

0.9

1.1

0.8

0.8

1.0

1.0

0.9

1.0

0.8

meq / L

1.6

0.9

0.9

1.7

1.0

2.5

3.5

1.8

5 .3

%

18.7

10.5

3.5

12.0

12.0

25.0

15.7

8.7

16.5

Exch. Sod ium Ca lcium:Magnesium Ratio Sod iu m Adsorption Ratio (SAR1:5) Exchangeable Sod ium Percentage (ESP)

Note: Figures in brackets are years irrigated with effluent. Eg Shepparton (10) has been irrigated for 10 years.

46

WATER SEPTEM BE R/OCTO BER 2000

WASTEWATER

400 -. . - - - - - - - - - - - - - - - - - - - - - - - - ~

Sodicity

Sodicity is ca used 350 by the presence of 300 250 so dium attached to 200 clay in soil. A soil is 150 co n sid e r e d so di c 100 w h e n th e so dium 50 reac h es a c riti ca l 0 concentra tion where Freshwater Irrigated Dry Pasture (Non Irrig ated) Effluent Irrigated it starts to affect th e soil 's stru cture . T he Figure 1. Nitrogen removed kg/ ha/ annum sodiu m wea kens the b o nds be twee n soil 50 pa rti cles when we tted , resulting in 40 the clay swelling and 30 o ft e n b ecom in g 20 detached. When this h app e n s, th e cl ay 10 particles spread out or Dry Pasture (Non Irrigated) Freshwater Irrigated EHluenl Irrigated disperse making the so il wa te r cl o ud y .

Figure 2. Phosphorus removed kg/ ha/ annum T h e di sp e rsed clay 10m g/ L P and 20-30 mg/ L N , respecparticles then m ove thro ugh the soil, tively), this issue is not critical. Research clogging pores . B oth swelling and disperwo rk carried out on perennial pas ture at sio n redu ce infiltrati o n and drainage and Shepparton has shown that nitrogen is lowe r th e ve ry imp o rtan t leac hing deficient w hile phosphorus is in balance. fraction of the soil.

T he wo rk also showed that efflu ent The result is hard setting, impermeirriga ted pasture had sup erio r nu trient able clays . T hese effects result in such uptake when compared to fres hwa ter problem s as poo r wa ter infiltrati o n , irrigated pas ture and dry pasture (Kerry et redu ctions in plant available wa ter capacal. 1995) (Figures 1 and 2) ity, poor seedling em ergence, poo r In addi tion , it should be noted that in ae rati o n and h ence poo r roo t developthe clayey soils of the Go ulburn Valley, m ent. Poor leaching, leading to perch ed soil phosph o rus bindin g capacity is very wa ter tables and an associated buildup of high and capable of adsorbing phosphotoxic elements can also resul t. T hese rus fo r ma ny decades. Provided runoff to effects lower plant growth rates and may external wa terways is largely prevented, rapidly lead to salinity . very little phosphorus w ill reach the It sh ould be noted that salini ty (too gro undwater. As nitroge n is utili sed by mu ch salt affecting the plant) is very plant gro w th, little risk o f nit roge n different to sodicity, which affects the contaminated gro undwa ter is present. structure of the soil. Sodicity can take a If nutrient rich industrial was tes are number of yea rs to develop and w hen present in substantial quantities (eg m ea t present can lea d to salinity (a nd o ther) processing was tes), careful assess ment of problems. nutrient levels in soils and gro undwa ter Sodicity is insidi ous, as it is often not will be required. noticed during efflu ent irrigation season while the electrical conductivity of the Plant Growth Rates irrigati on water is relatively high and In discussions w ith fa rm ers utilising exceeds the threshold condu ctivity levels. efflu ent fo r irrigation of pas ture, their Sodic effects m ay however result w hen co mm en ts ar e in va ri a bly sirn.il a r. w inter rainfall lowers this soil EC levels.

Comments such as " my pas tu re looks healthi er" o r " the paddocks are greener Effluent and Sodicity than they we re w ith channel wa ter" are T he risk of sodicity is high with many com111011. efflu ents as high levels of so dium based T hese types of comments are also salts are often present due to industrial supported by resea rch. O n a well- managed wastes, gro undwater infiltratio n, and salt site, pasture growth ra tes at Shepparton present in do m estic was tewater. have bee n de m o nstra ted to be 32% W hen combined with clayey soils, superior to pastures itTigated only with these efflu ents can ca use so di city to freshwa ter (Figure 3). T his has been develop over a period of yea rs. attributed to the nitrogen-phosphorusT his effect is shown at a resea rch site potassium balance in the efflu ent and in Shepparton w here soils have been possibly other constitu ents such as organic m o nito red over a period of 10 yea rs and matter fro m algae (Kerry et al. 1995).

the accumulation of sodium is apparent.

(Figure 4) . It is noticeable that w hile topsoil sodium has stabilised over the las t 5 years, subsoil sodium is still increasing.

T his is possibly due to the additio n of gypsum. During this later 5 yea r period the EC l :5 has been stable w hile the soluble chlo ride has decreased in the topsoil and increased in the subsoil.

Efflu ent charac teristics fo r Shepparto n we re shown in Table - .

It appears that sodium and chloride are leaching thro ugh to the subsoils. At the present stage plant resp onse to these changes are not m arked at this permanent pasture site. R yegrass pasture yield still appears sup erio r to channel irrigated pas ture.

Management of Soil Sodicity The m anagem ent of soil sodicity can be divided into two areas - m anagem ent of efflu ent quality and fa rm manage m ent wo rks.

Effluent Quality Efflu ent quality can be impac ted by wa ter authori ty policies. A clear example of this is the introdu ction of strong trade was te policies by Go ulburn Valley Water to mini m ise so diu p1 in in d u stri al discharges. This includes regulation of sodium and salt loads from industries, encouragem ent of waste minimisatio n prac tices in industry and m ost imp ortantly, the introdu ction of charges fo r sodium on an ongoing basis . Sodium is also a co mp o n en t o f was t ewa t e r headwo rks charges for these indu stries .

T hese policies are refoc ussing industry in the Go ulburn Broken R egion on the mini misation of salts harmful to irrigation. Maj or foo d processing industries are now abandoni ng the use of ca ustic soda in some produ ction lines and introd ucing caustic soda recovery systems fo r areas w here the chemical ca nnot be eliminated.

Works to prevent saline gro undwa ter infiltration to sewer have, to date, only been m oderately successful, and the high cost of minimising gro undwa ter infiltrati on is also a si g ni fica n t iss u e .

Neverth eless, sewer subcatchments are assessed fo r high condu cti vity rea dings to better target rem ediation wo rks.

Farm Management Practices Despite a soil being assessed as by chemi cal analysis as sodi c (ESP >6), the physical effec ts o n th e 'soil ca n be minimised by adopting som e of the fo llowing fa rm prac tices .

T he m ost recommended practice is generally the use of gypsum (calcium sulphate) . Positively charged calcium ac ts by being strongly attrac ted to negatively

WATER SEPTEMBER/ OCTOBER 2000

47

WASTEWATER

Finall y, th e r e now appears some 50 evidence that the l! addition of organic 40 i~ matter to soil retards 30 t the development of i! 20 structural problem s § 10 in so dic so il s.

Experim e nts with th e r e tention of -:,'b<fO:,~-l':,~'l>.i.:,0:," -:,'30:,~0.,~?,\'b<::-o.,'l,~?J:'b"O:,'l, -:,-YrJ},cl'o.,~.:,,?J\'b<fo.,~-l'>:'1>"0:,"J ':,~o.,:,jfo.,:iS''?J\~°"'~~'*~,, "'"" stubble (rather than --e-Effluent Irrigation ~Freshwater Irrigation -+-Dry Pasture (Non Irrigated) burning it) , particuFigure 3. Cumu lative pasture production l arl y w h en co mbin e d with charged clay particles and displa cing gypsum resulted in significant improvesodium. This causes the soil to more m ents in soil physical and chemical freely drain. The sodium then leaches to properties (Valzano et al. 2000). As many · the deeper subsoils beyond the root zo ne water authorities have significant quantiof the plant. ties of biosolids from treatment plant In many instances gypsum works well, processes, these biosolids may well prove but there is now some overseas evidence beneficial in rem ediation of sodi city that unless the sodium can be leached affected soils. deep into the subsoil and/ or externally The Challenges for Long Term drained, eventually salinity may result Sustainability of Effluent (Gafni and Zohar. 2000). Work carried Irrigation out by Agriculture Victoria Tatura at one of the Goulburn Valley Water irrigaAs can be seen from the exchangeable tion sites indicates gypsum is effective for so dium graph above, the chemi cal topsoil but little impact is seen on subsoils changes in a soil can take many years to where sodium continu es to acc umulate develop . It is important for a w ater (Surapaneni et al. 2000) . authority to initi ate a lon g te rm It also appears that farm practices that monitoring program for key indicators minimise the disruption to soils are also and monitor ch emical changes in the beneficial to maintaining adequate leachsoil. These soil results need to be ing capabilities and reducing sodicity combined with a regular assessment of e ffec ts (Issac Sh ainberg, personal plant growth trends and soil characteriscommunication) . This includes the utilitic assessments. sation of perennial pasture w here good In addition, water authorities need to root growth is maintained. Animals adopt policies that minimise sodium salt should also be removed during periods ingress into sewer systems. This includes when the soils are wet (eg after irrigation strong industrial waste policies directed at or heavy rainfall). waste minimisation and so dium salt In cropping situations, minimum redu ction along with groundwater infiltillage should be practiced to restrict soil tration prevention programs. disruption. There is now also overseas W e also need to adopt appropriate evidence that watering systems that result farm management prac tices, which take in slow we tting of the soil (< 10mm/ hr) into acco unt current Australian and minimise structural changes to the soils, overseas research on eillu ent irrigation despite the soil being chemically sodic. and its effects on soils.

This includes the use of microsprays and Given these constraints, there is no dripp ers (Oster and Shainberg 2000, reason why eilluent irrigation cannot be Shainberg et al. 2000). carried out sustainably for the long term and there are goo d reasons for the 30~--------------------~ expansion of eilluent 25 irrigation . This is / parti cularly important, as wa ter 1s no w a scarce commodity rn th e Murra y Darling Basin.

60

,,

References Start

Year 2

Year3

Year 5

-Topsoil -Subsoil

Figure 4. Soi l exc hangeable sod ium with t ime

48

WATER SEPTEMBER/OCTOBER 2000

Year 10

Environment Protection Authority Vi cto ri a (1991) Guidelines for Wastewater Irri gation,

Publication No 168 Environment Protection Authority Victoria (1996) Guidelines for Wastewater R e-U se, Publication No 464 Kerry P.J. , C raig A.J. , TisdallJ.M. , White R.E. , Gardner B ., Ugalde T.D. (1995) Fate of Nutrients Supplied in Wastewater Used to Irriga te Pasture. Murray Darli ng Basi n Commissio n NRMS Project V144 .

Gafni A. and Zohar Y., (2000) - Bio-drainage and Sodicity in Israel In: Sodicity Issues in Agricultural Industries C urrent Research a nd Futur e Directions. Inte rnational Conference held at Tatura. 28 Feb 1 M arch 2000.

Shainberg I, Levy G.J. , Goldstein D., Letey J. (2000). Effect of Prewetting R ate o n the Prop e rti es (Hydrau l ic H y dra uli c Condu ctivity and Infiltration Rate) of Soils.

In: Sodicity Issues in Agricultural Industries C urrent Research and Future Directions.

Intern ation al Conference held at Tatura. 28 Feb 1 March 2000.

Surapaneni A. , O lsson K. A. , Burrow D. P (2000). A R eview of Sodicity Research in Irrigated Pastures. In: Sodicity Iss ues in Agricultural Industri es C urrent R esearch and Future D ir ec tions. Int ernational Conference held at T atura. 28 Feb 1 M arch 2000.

O ster J.D. , and Shainoerg I. , (2000). Soil Response s to Sodicity and Sa linit y : C hallenges and Opportunities. In : Sodicity C urrent Issues in Agricultural Industries R esea r c h a nd Futur e Directions .

International Conference held at T atura. 28 Feb 1 March 2000.

Valzano F.P. , Rengasa my P. , Green R.S.B. , Jarwal S. Murphy B.W. (2000). The Long Term Effects of Gypsum and Stubble M anagement on the C hemical and Physical Properties of a Sodic Grey Vertisol. In: Sodicity Issues in Agric ultural Industries C urrent Research and Future Direc tions.

International Conference held at Tatura. 28 Feb 1 March 2000.

Acknowledgments Considerable work on Goulburn Valley Water sites has been carried out by a number of staff at Agriculture Victoria - Tatura. Vanessa H ebbard and George Wall from Goulburn Valley W ater have also assisted greatly.

Authors Peter Don lon is Environmental Services Manager at GotJlburn Valley Water (P .O. Box 185, Shepparton, 3632 (email peterd@gvwater.vic.gov.au) . Dr. Aravind Surapaneni is a senior research scientist at Agriculture Victoria -Tatura.

(Ferguson Rd . Tatura , 3616 (email aravind.surapaneni@nre.vic.gov.au)

WASTEWATER

SPUDS AND FLOWERS: THE BARWON WATER GREEN INDUSTRY PROBE C Howie produ ced in rotation . The grower B ar wo n W at er's l ar ges t currently has a 12 m onth agreem ent sewage treatment plant, Black with Barw on Water for a reclaimed Ro ck , is loca t e d b e twee n water supply.

Torqu ay and Barwo n H eads, on Vi ctoria's Surf C oas t. Blac k T his is likely to b e extended in R ock trea ts the maj ority of Septemb er this year. Potato growing sewage fr o m th e G ee lo n g in the Geelong region has had varied region and produces good Class su ccess in the past due mainly to C reclaimed wa ter suitable for uncertain rainfall. For several yea rs, reuse . reclaimed wa ter has been recognise d B arwo n W ater h as b ee n as a potential solution to address the developing ben efi cial use of wa ter deficit. P ro duction of potatoes reclaimed water from this IDEA Initial trials on the potato patch (utilising reclaimed wa ter irrigation) plant, believed to be the largest in th e T o rqua y ar ea b ega n in been successfull y grown using Blac k of its kind in the world. Black Rock D ece mb er, 1999, and foll owe d an Ro ck reclaimed wa ter. T o date, the r e cl aim ed wa ter h as an el ec tri ca l ex tensi ve r esea rch trial condu cted gro we r has leased land fo r on e crop per conductivity gen erally in the range 1700 yea r with cereal/summer crops being betwee n February and'June, 1999 .

- 2300 µmh os/ cm , but is currently ave raging about 1900 µmh os/ cm .

While land disposal to w oodlots is in op eration at some smaller sewage trea tm ent plants, the Green Industry Prob e is an extensive feasibility study into furth er developing the utilisation of Bl ac k Ro ck r e cl aim e d wa t e r for commercial uses.

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Sandy- type soils are well suited to both horticultural production and irrigation with reclaimed water. In their natural state, sandy soils ca n b e infertile .

However, this is addressed via application of organic manures (poultry shed was te) and fertilisers .

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The trial was conducted by tanking wa ter to the site, but infras tru cture has n ow been ins talled .

T he trial, co nd ucted in partnership be twee n NRE , Barwo n Wa ter and growers, was undertaken to : • Address the lac k of scientific info rmatio n regarding the use of high nutri ent wa ter fo r potato produ ction • Confirm the sui tability of the po ta toes fo r human co nsump tio n • Inves tiga te th e affec t o n growth of the plant itself • Analyse th e impac t on yield (comparing with fresh wa ter irriga tio n , and no irrigation).

A fu ll repo rt has been prepared by NRE and is expected to be released soo n. In essence , it fo und that potatoes irriga ted w ith recl ai m ed wa ter are suitable for hu man consumptio n . As a preca utio nary meas ure, N R E stipulated a chlorinated was h before processing and packa ging and that sa mpl es be taken fo ur wee ks befo re harvesting, and analysed fo r E .coli and salm o nella.

O ther existing users of reclaimed wa ter in the area include vineyards, turf produ ction and golf co urses . A tri al of growing hydroponic tom atoes also is being condu cted.

T h e k ey p rin cip les in B arwo n W ate r's re-use policy are:

• R eclaimed wa ter has a commercial value • Any re-use projec t must be commercially viabl e • An y reuse p roj ect m ust be environm entally and technically sustainable • R isk must be 111..ini mised with Risk Strategy and an EM S • Infras tru ctu re costs to be m et by users (beneficiari es) • Use r-pays based o n a volume tariff, but w ith disco un ted start- up charges

Author Cameron Howie is R euse O ffice r at B arwo n Wa ter. E m ail ca m e ron h@ barwo nwa ter. vie.gov .a u

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This will include liaising with senior industry staff to identify, develop, fmance and undertake innovative R&D projects that will bring substanti al benefits to Singapore based industry.

T hi s pos ition requires a hi gh degree of technica l experti se, ex tensive experience in the deve lopment and appli cation of modern wastewater treatment technologies, and a demonstrated capacity fo r inn ovation. It will also require effecti ve tea m-management experi ence.

Requirements: You should have a PhD in Chemi ca l Engineering/Che mi stry or equ ivalent. Yo u should have a mi nimum of 15 years' ex perience in app li cati on of membrane techn ology (MF/UF/RO) to industri al wastewater and recycli ng. In add iti on, you should de monstrate strong abi lity to conce ive and manage signific ant R&D programs as well as demonstrate good people management ski ll s in the R&D environm ent. You shoul d also have excell ent communi cation skills in written and spoken English.

Job Duties: T he successfu l candidate will develop proj ects, plan and supervise laboratory test work programs, des ign and co mmi ss ion pi lot plants and prepare proj ect reports. This will require industri al experience of modern waste water treatment techno log ies and demonstrated project management skills. It will also require cl ose interacti on with Singapore industrial sectors.

Requirements: You shoul d have a PhD in Engineering (Chemical/Environmental), Chemistry or equi valent. You should have at least 5 years of experience related to wastewater treatment R&D. Substantial experience in the application of membrane technology (MF/UF/RO) to indusuial wastewater recycling and proven ability to unde1take economic evaluations of alternative technologies is pre-requisites. In addition, you must al o be competent in both written and spoken English.

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WATER SEPTEM BER / OCTOBER 2000

Industrial Research· Scientist Electrochemistry/Wastewater Treatment Job Duties : The successfu l candidate will develop projects, plan and supervi se laboratory test work programs des ign and co mmiss ion pilot pl ants and prepare project reports. T hi s will requi re in du stri al experi ence of modern wastewater treatment techn ologies and de monstrated project management skills.

It will also require close interaction with Singapore indu stri al sectors.

Requirements : You shoul d have a PhD in Chemi stry, Engineering (Chemica l/Environmental) or equi va lent. You should have at least 5 years ex perience related to wastewater treatment R&D . Substanti al ex perience in the appli cation of electrochemi cal techn iques to industrial wastewater treatment and a proven ability to undertake economic evaluati ons of altern ative technologies are pre-req uisites.

In add itio n, you must also be competent in both wri tten and spoken Engli sh.

Suitable candidates are invited to apply . Please state the post you are interested In on the application letter . We will offer an attractive remuneration package to the successful candidate . Log on to http://www.eti.org .sg for more details on ETI. Please write in with detailed resume , stating current and expected salary and a nonreturnable photograph to : The Human Resource Manager, Environmental Technology Institute Innovation Centre (NTU) Blk 2, Unit 237 , 18 Nanyang Drive , Singapore 637723 Email: ETIDEPT@eti.org.sg

ll1

ENVIRONMENT

Summary Th e Urban Plat y pu s Pro g r a m cond u c t e d b y M e lbourn e Wat e r Corporation (MW) illu strates th e need for waterway managem ent age ncies to develop clear goa ls for protec ting and e nhan cing e n vironme ntal val ues in waterways. One goa l in MW 's management of M elbo urn e's wate rways is to ens ure that viable platypus populations occur in strea ms capable of supporting th em. An integrati ve approach occurs thro ughout MW's activities to ac hi eve this goal. R esearch is condu cted o n pl atyp us distribution, ab undance and population dyna mi cs, and to identify those environmental issues that most effect platypus. Findings from current resea rch are appli ed to work programs that ca n enhance and protec t platypus.

A review of work practices in bed and bank stabi li za ti on , willow removal and we tland co nstru ction has also bee n co nd uc ted to e nsure that minimal destru ction of platyp us habitat occurs durin g works and , if possible, to predict how the completed works will ass ist th e long term viability of platyp us.

ar e monitor e d fo r wa t e r qualit y, toxican ts in sed im ents, E. coli, litter an d biota. Biological monitoring primarily in volves the use of aq uatic m ac roinve rtebrates, altho ugh fi sh, platypus, benthic diatoms, blu e-green algae and m ac roalgae are often surveyed in ca tchment studi es (MW, 1998a) . Platypus are an important valu e, ye t we had no information regarding w here they occ ur in the G reater Melbo urne regio n , nor w hether o ur waterwa y mana ge m ent activities were effecting platypu s.

The Urban Platypus Progra m , w hich is a joint initiati ve between MW and the Au strali an Platypus Conservancy (APC) , co mm enced in J anuary 1995 . The aims

of this program are to: • determine the current distribution and ab undance of platypus in M elbo urn e's waterways, • identify tho se fa ct~rs w hi ch limi t platyp us distribution and abundan ce in urban wa terwa ys, • mana ge M elbourn e's waterwa ys in a manner that w ill protect sustainable pl atypus populations, and • edu cate the p ubli c about wate rway issues .

The Urban Platypu s Program has assisted in developin g fo cused managem ent obj ec tives for M elbourne's aq uatic ecosyste ms and has become the fla gs hip for th e Healthy Waterwa ys Program ,

Why study platypus for waterway management?

M e lb o urn e Wa t e r Co rp oratio n (MW) condu cts a variety of wo rks to improve wa ter quality, physical stream condition and supp ort h ealthy aqu atic ecosystems in th e greater Melbo urne region (MW, 1997). A broad spec trum of environmental data is collected to assess th e state of wa terwa ys and how th ey are changin g over tim e. W aterways

0

e-

I

10

20 3

Kilometres

Figure 1. The distribution of platypus in t he Greater Melbourne region , based on surveys conducted by the Au stra li an Platypus Conservancy since 1995. Platypus occur in tho se waterways denoted by a thick light blue li ne and were not co ll ected in waterways denoted by a red line. Surveys were not conducted in areas with a fine dark blue line.

WATER SEPTEMBER/ OCTOBER 2000

51

ENVIRONMENT

and an important vehicle for publi c education about the numerous wa terway iss u es th at o cc ur in th e M elbourne region . R esearch gen erated from the APC and from the MW environmental programs have been used to modify waterway m anagem ent activities . With rare exceptions, MW wo rk programs are not primarily intended to protect or enco urage platypus populations, but are intended to mitigate flooding, improve wa ter qu ality, reduce stream erosion or remove exotic willows. Even so, this pap er illustrates how minor modificati on s h ave bee n m ade to work programs to redu ce impac ts on platypus, and in some instances, provide new habitat that may assist in establishing healthy populations.

Platypus T h e pl atypu s (O rn ithorh ynchus anatinus) is an unusual and secretive egg-laying mammal. After hatching, the young are fed on milk and remain in a burrow dug into the stream banks for about three to four months (Serena, 1993) . Platypus are n octurnal animals that usually spend the day in a bu rrow.

At night, platypus fo rage fo r mac roinvert e bra t es and oth e r foo d usin g electroreceptors located on the end of their bills (Grant, 1989) . M ales appear to compete to hold a breeding territory, which may extend ove r several kilometres of waterway . Platypus have been recorded travelling up to 10 km (males) and 4 km (females) during one night (Serena et al., 1998) .

Platypus are widespread and co mmon residents of perman ent wa terways in Tasmania, Victoria, N ew South W ales and Qu ee n sland , as fa r n o rth as Cooktown. T hey have also been introdu ce d to Kan garo o Island , South Au stralia in 19 40 (G r ant , 1992) .

Anecdotal evidence suggests that platypus numbers have declined in some regions, notably in the Murray River downstrea m of Echu ca, and urb an wa terways in M elbourne and Sydney (G rant, 1992) . The reason fo r this decline in urban wa terways has been attributed to "changes to rivers, including the constru ction of dams, rive r improvement and channelisation and the effec ts o f eros io n " (Grant , 1989).

Populations in headwater streams may also become isolated as lowland wa terways become polluted or degraded, or large on-stream barriers are constru cted (p erso n al ob se rvation ). P o or wa ter quality may not directly affect platypus, but p oor wa ter quality can reduce the

52

fa ctors influencing platypus distribution and abu ndance in urban wa terways, and to develop work programs that wo uld minimize impac ts.

Urban Platypus Program

Geoff Williams of the Australia Platypus Conservancy and Caroline Carvalho, an environmental scientist with Melbourne Water, set up a tunnel net used to trap platypus.

amount and type of foo d resources, and therefore indirectly influence the distribution of platypus (G rant & Carrick, 1978) . A maj or aim of this platypus program was to establish the maj or

WATER SEPTEMBER/ OCTOBER 2000

Since 1995, platypus surveys have been condu cted in virtually all streams in the Greater M elbourne R egion .

Consequently, aycurate info rmation has been gathered on the distribution and abundance of platypus in the region (Figure 1).

These surveys provide a detailed distribution map of platypus in the M elbourne region. R egular surveys are now being conducted along many wa terways to gather long-term info rmation about population dynamics and stability.

Information has also been ga thered on the fac tors that influ ence the distribu tion and abu ndan ce of platypus in the study area. As part of the surveys co ndu cted during 1995 and 1996, details w ere gathered on the enviro nmental conditions inhabited by platypus (see Pettigrove, 1999, for further details).

Platypus, in the greater M elbourne area, tend to occ ur in stream reaches that have

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blackberries alon g th e banks, where th e banks are ve rti cal or undercut, where there is a large amount of snags , and w here the water is well oxyge nated wi th low levels of fa ecal contaminants and there is no stream sediment odo ur.

Similar correlations between platypus and invertebrate famili es suggest that the presence of riilles and runs is an important factor influencing platypus in the M elbourne region , as th ese habitats may provide a better source of food than pools in som e waterways (Pettigrove, 1999) . The importance of riilles and runs is also supported by observations that platypus tend to locate burrows near these habitats and that platypus spend a larger proportion of time fora ging in riilles and runs than in pools (Serena, personal communica tion).

Protecting the platypus A large proportion of platypus captured during surveys were tangled with litter, including fishing line and elastic bands, which in many cases wo uld lead to life threatening injuries (Serena & Willi am s, 1998a).

Th e refor e, the control of litter through public education and stormwater mana ge m e nt program s w ill assist in protecting platypus in receiving w aters.

Platypus may be resilient to stream works if approp riate measures are taken (Serena & Williams, 19986). MW has de veloped standard work procedures for bed and bank stabilization (MW, 19986) .

These procedures provide options for minimizing environmental impacts on platypus and oth er biota. They are considered to be working do cuments that will be upgraded as additional information arises . Both procedures recomm end several practices if platypus are known to occur at a site w here works are . planned . To reduce the chance of platypus burrows collapsing from works: • th e u se of h eavy machin e ry is restricted along strea m banks; • soils removed as part of works are stored more than 10 m from the stream banks, and • wa terway works usually do not occur betwee n October to January, when platypu s are breeding and juveniles are confined to the breeding burrows.

MW will ow remo va l gu id elin es (MW, 1998c) also recommend: • using appropriate methods in areas of high environmental sign ifi cance, such as hand work in preference to the use of m ac hinery, or using special ma chinery that can remo ve trunks from a safe distance from the waterway, and

• re tainin g so me w ill ows or d ea d remnant trees, or phasing removal of willows to provide interim habitat, if little or no other habitat is present.

Radio-tra cking studies have demonstrated that many barrier structures are not impassible to platypus. For example, a male platypus in Monbulk Creek has been found to move through a drop structure; a pip e 45 m long and 1.35 m internal diameter, at a gradient of 1 in 87. During normal feeding activities, platypus tend not to pass over barriers, possibly beca use they require considerable energy or the y ma y be exposed to predators (Se re na et al., in press) .

Although many on-stream barriers are not impassible for platypus, they are impassible for many native diadromous fish , and are still being remo ved as part of the MW works program .

Undercut banks are often considered to be a feature that contributes to poor stream condition and therefor e will score low in many stream assessment methods (e .g. Ladson & White, 1999). As undercut banks are a sign of bank instability, they are often prioritized for removal in stream impro vem ent programs (MW,

1998b). Y et, our current understanding of platypus requirements challenges these perceptions.

In past decades, many of Melbourne 's waterways were completely stabilized using concrete or large rocks. Undercut banks were remo ved, by the banks being cut back to more gentle slopes. In recent yea rs, MW stream stabilization involves o nl y a small proporti 1 of w aterways undergoing works, with drop structures, or riffles being constructed at strategic locations . This approach would greatly redu ce the chance of platypus burrows being damaged. Approximately 20% of banks and channel within a 1.1 km long section of the Diamond Creek had extensive reshaping and stabilization with the use of large rocks. Within this section, only two of the known 27 platypus burrows were destroyed as a result of these works (Serena & Williams, 1998b) w ithout any loss of platyp us. In contrast, pas t practices may have resulted in the destru ction of all burrows.

These results challenge p erceptions abo ut undercut and other steep banks as being undesirable, as they can provide secure platypus burro""(S and therefore

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ca n be an important habitat contributing co health y waterwa ys. This has encouraged MW waterwa y engineers not to remo ve undercut banks per se, but only w hen w arranted by other issues .

The amount and type of riparian vege tation cover also appears to be important co protect pl atypu s from potential predators such as dogs and fo xes (Grant, 1989). Large revegetation program s of riparian zon es initially involve clearing w eeds and it n1.ay take several yea rs befor e new vegetation provides adequate cover for platyp us. As a result, efforts are made to stage revegetation along portions of a reach , to provide some areas of refu ge for platypus.

Creating platypus habitat Platypus appear to be opportunistic animals that w ill qui ckl y coloni ze suitabl e habitats. For exa mple, bed and bank stabilization w orks we re condu cted in the Mullu m Mullum Cree k, a small urban trib utary of the Yarra R ive r.

Soon after completion of the works, a juve nile male platypus was captured near this site, more than 1 km upstream of pr ev iou s pla ty pu s e n count e rs (Williams et al. , 1998). The opportunistic behaviour of platypus has encouraged MW to consider whether constru ction w o rks can be design ed to provid e suitable habitat.

A lack of flows in the Diamond/ Arthurs Creek during a large proportion of the year was identifi ed as the major reason limiting platypus and other bio ta in thi s sys tem (P e tti grov e, 19 98) .

En vironmental flows have since been released by MW during periods fro m a small reservoir in the headwaters of Arthurs C reek. These flows, and the subsequ ent creation of a less stressed aquati c ec o sys tem is prob ably th e primary reason w hy platypus have since returned to some upper sections of this ca tc hm ent (Williams & Serena, 2000).

Are platypus indicators of stream ecosystem health?

In recent yea rs, ecological indi ca tors (ma croin vertebrates and native fi sh) and o bj ecti ves ha ve been included in th e Vi ctorian State Environment Protection Policy (SEPP) , W aters of Victoria , but complian ce monitoring is not required for platypus. E ven so , MW is monitoring platyp us, as it is a direct m easure of how successfu l environmental mana gem ent can be in supporting a viable population and it is an important environmental valu e that can readily be

54

appreciated by th e ge neral co mmunity .

Platypus are an impo rtant indicator of ec osys tem h ealth, as th eir viabili ty appears to be affected by water and sediment quali ty, flo ws , instream and riparian habitat and th e amount of available food. Our und erstanding of platypus requirem ents can help M elbourne Water focu s on the most important environmental issues that will produ ce tangible outcomes .

Anoth e r m an age m e nt approa c h would be to improve compliance with SEPP environmental qu ality obj ectives .

For example, millions of dollars ma y be all ocated to red uce suspended solids c onc e ntration s 111 a wa t e rwa y .

However, such expenditure may only be worthwhile if it redu ces risks to human health, or results in impro ve m ents to significant environmental valu es, rather than just improving the level of compliance to SEPP obj ec ti ves .

Application to other waterway authorities This program illustrates the need for w aterw ay authoriti es to ensure that goals are clearly established for improving w aterways . Thi s ca n h elp age ncies develop a more fo cused strategy to identify primary environmental issues, identify what research is required, help id entify re h abilitatio n proj ec ts and refl ec t on th e adequ acy of current programs to achi eve e nvironmental goals.

Acknowledgments The platypu s distribution map was prepared by Rhys C oleman . Thanks to Bob Swinton, P eter Scott and Kevin Wood for editorial comme nts and M elody Serena and Geoff Williams and other APC staff for their excellent platypus studies .

References Grant, T.R. and Carri ck, F.N. (1978) Some aspects of th e ecology of th e pl atypus, Omit/, or/1 yc/,11u s a11a ti11 us, in th e up pe r Shoalhaven Ri ver, N. S.W. A ustralianJournal of Ecology 4: 171-179.

Grant, T.R. (1989) The platypus- a uniqu e mamm al. N ew So uth W ales Uni versity Press (seco nd edition) .

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R oyal Zool ogical Society of N ew South Wales, M osman , N SW. M elbourn e W at e r Co rp o rat io n ( 199 7) M elbourn e W ater: managing o ur water resources. Annu al report 1996/ 97 .

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& W estern Port catchm ents: ann ual stream

h ea lth m o nit o ri n g re p ort 1997 .

(Eds .Coleman, R , Batty, M and Petti grove , V).

M elb o urn e Wat er Co rporat io n (1998 6) Standard works procedure #9. W illow control & managem ent.

M elbo urn e W ater Corporati on (1998c) Aspect improvement plan #2 . Bed and ba nk stabi lization .

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In 'Co mprehensive Storm water & Aquati c Ecosys te m M an age m e nt - Co n fe re n ce Papers', Volum e 1, pp.223-231.

Serena, M . (1993) Platyp us - helpin g chem in the w ild. Land fo r Wildli fe note no.27.

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Serena, M. and Willi ams, G.A. (1998a) Rubber and plasti c rubbish: a summ ary of th e haza rd posed to platypus Or11ir/,orhy11c/111s a11ati1111s in suburban habitats. T/,e Vicroria11 Na t11 ralis1 115(2): 47-49.

Sere na, M. and W illi ams, G .A. (19986) Effect of stream stabili zati on works on platypus be haviour alo ng Diamond Creek (Yarra l:i...iver catchment). R eport to M elbo urne Water. Australi an Platyp us Conse rva ncy: Whittl esea.

Serena, M ., Thomas, J.L., Willi ams, G. A. and O ffi cer, R .C.E . (1998) Use of strea m and ri ve r hab it ats b y th e pl a t ypu s, Or11ithorh y11c/111s a11ati1111s in an urban frin ge environm ent. A ustralia,, j o11rnal of Zoology 46: 267- 282.

Vi ct or ian Gove rnm e nt Gaze tt e (1999) Vari ati o n of t h e Sca ce Env iron m e n t Protection Policy (Waters of Victoria) inserti on of Schedule F7. W aters of th e Yarra Catc hment. N o S 89 Tu esday 22 Jun e 1999.

W illi am s, G. A. and Seren a, M. (2000) .

Distribu tion of platypus in th e M elbo urn e m e trop o lit an are a. S urvey res u lts, 1999/ 2000. A report to M elbourn e W ater.

Au str alian Plat ypu s Co n se r va n cy : Whittl esea .

Willi ams, G.A., Serena, M and Th omas, J.L. (1998) Distribu tio n of pl atypu s in the Mel bo urn e metro politan region . Survey results, 1997 / 98. A report to M elbourn e Water (Waterways & Drainage Group).

Author Vincent Pettigrove is Principal Li mno l o gist with Wat e rw ays & En v i ronm e nt, M el bourn e Wat e r Corporation, Locked Bag 4280, East R ichmond , Victoria , 3121 , Australia.

T el. (03) 9235 2106 Fax 9429 71 74 Email v in.p e tti g ro ve@ melbw a t e r. com.a u