Water Journal October 2001

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Volume 28 No 7 October 2001 Journal of the Austra lian Water Association

Editorial Board F R Bish op, Chairman B N Anderson, R Considine, W J Dulfer, G Finke, G Finlayson, G A Holder, B Labza, M Muntisov, P Nadebaum,J D Parker, J Rissman , F Roddick, G Ryan , S Gray

CONTENTS

,._ Water is a refereed journal. This symbol indicates that a paper has been refereed.

2

FROM THE FEDERAL PRESIDENT: AWA Activities

Submissions

3

FROM THE EXECUTIVE DIRECTOR: A Legal Bent

Sub missions should be made to E A (Bob) Swinton, Technical Editor (see below for details) .

4

INTERNATIONAL AFFILIATES: WEFTEC 2001

6

OVERSEAS REPORT: On the beach .•. in London K O'Halloran

8

MY POINT OF VIEW:

Managing Editor Peter Stirling PO Box 84, Hampton Vic 3188 Tel (03) 9530 8900 Fax (03) 9530 8911

Where to Next on Water Quality Standards Dr Neil Byron

Technical Editor EA (Bob) Swinto n 4 Pleasant View Cres, Wheelers Hill Vic 3150 Tel/ Fax (03) 9560 4752 Email: bswi11to11@bigpond.net.au

12

CONFERENCE ROUNDUP

14

WATER AWARDS: Thiess Services Riverprizes

16

CROSSCURRENT: Water News Around the Nation

Crosscurrent Editor W (Bill) Rees PO Box 388, Artannon, NSW 1570 T el +6 I 2 9413 1288 Fax: (02) 94 I 3 I 047 Email: brees@awa.asn.au

FEATURES: GROUNDWATER AND SALINISATION

27

AWA Head Office PO Box 388, Artannon, NSW 1570 Tel +61 2 941 3 1288 Fax: (02) 9413 1047 Email: info@awa .asn .au

Water Advertising & Production Hallmark Editions PO Box 84, Hampton, Vic 3188 Level 1, 99 Bay Street, Brighton, Vic 3 I 86 T el (03) 9530 8900 Fax (03) 9530 89 11 Email: hallmark@halledic.com.au Graphic d esig n : Mitzi Mann

I Lambert, K Lawrie and C Pain

Catchment management requires information from deep down in the regolith.

30

Electromagnetic, Radiometric and Magnetic surveys map sub-surface salt

34

ABN 78 096 035 773

Federal President Barry Nonnan

Executive Director Chris Davis

...

AWA

New methods give better estimates of groundwater behaviour

Australian Water Association (AW A) assumes no responsibility for opinions or statements of facts expressed by contributor.; or advertiser.;. Editorials do not necessarily represent official A WA policy.

Advertisements are included as an infonnation se,vice to readers and are reviewed before publication to ensure relevance co the water environment and objectives of AW A. All material in Waler is copyright and should not be reproduced wholly or in part without the written pennission of the General Editor.

Subscriptions vVa1er is sent co all AW A member.; eight times a year.

It is also available via subscription.

Visit the A

oc at o

A regional-scale groundwater model estimates salt fluxes

41

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HOME PAGE

and access news, calendars, bookshop and over 100 pages of Information at

,] SALINITY ASSESSMENT WITH HARSD: LITTLE RIVER CATCHMENT, NSW S W Dav ies, D Poll ock, WA Milne-Home, RB Salama

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AUSTRALIAN WATER ASSOCIATION

!~l A FRACTURED ROCK AQUIFER: THE CLARE VALLEY PROJECT P Cook and A Love

is published eight times a year in the months of January, March, April, J une, July, September, O ctober and D ecember.

Australian Water Association

·,] AIRBORNE GEOPHYSICS: BETTER INFORMATION FOR LAND MANAGEMENT G Street

37

Water (ISSN 0310 - 0367)

MAPPING AND UNDERSTANDING SALINITY IN THE LANDSCAPE

•, AQUIFER STORAGE AND RECOVERY: REMOVAL OF CONTAMINANTS FROM STORED WATERS S Toze, P Dillon, P Pavelic, B Nicholson, M Gibert

An international project investigates quality changes underground

WATER 4S

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WATER AND WASTEWATER MINIMISATION: THE FISH PROCESSING INDUSTRY IN SOUTH AUSTRALIA B Dearman, N McClure and H Fa ll owfield

Simple changes to factory systems pay off handsomely

ENVIRONMENT SO

" DESIGNING AMONITORING PROGRAM FOR ENVIRONMENTAL REGULATION: PART 1 - THE OPERATING CHARACTERISTIC CURVE W Paul and N T Diamond

Compliance or non-compliance? You could be 50% out!

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MEMBERSHIP

S6

MEETINGS

OUR COVER: The Natio11al Actio11 Pla11 for Salinity and Water Q11ality was am101111ced last year, to the t1111.e of $700 M from the Co111 n1on.wealtl1. Salinity expresses itself at the su,jace, b11t its ca11ses lie deep 1mdergro1111d, and the Bureau of Rural Sciences is directing a Salt !Vlappi11g Program. Groundwater investigations no longer rely solely 0 11 datafro,n drillholes: techniques de11eloped for mineral exploratio11 are 110111 being applied.

Photo by Wayne Lawler courtesy of AUSCAPE.

FROM

THE

PRESIDENT

C ANRI: Co mmunity Access to Natural R eso urces Information, an initiative of the NSW Government, is an exciting new website. It contains a mu ltitude of information on NSW rive rs, catc hm ents, so ils, salinity, vegetation, wildlife, and mu ch more. It combines websites from a variety of sources including Government, local councils, non- profit groups and other organisations. Some of the data, such as river and water reservoir heights is very close co real time. It is also possible to add maps from your own organisation's website to CANRI.

AWA ACTIVITIES Dealing with Australia 's intractable water problems, including salinity, river health and better water allocation, is only going to be successful if there is a groundswell of public support. Driving one group into the ground simply doesn't work, because people defend themselves vigorously when their backs are to th e wall. To use the D eputy Prime Minister's words when he launched Ticky Fullerton's book, Watershed, earlier this month, we have to 'share the burden'. Partly, that means mechanisms chat help affected communities to adapt to a new order, but it also means having everyone pulling in th e same directi o n; having common goals and a shared understanding.

Step one, of course, is to have people understanding water issues better than they do now. We are already caking steps in that direction, with the We All Use Water project. In case yo u haven' t seen it yet, this is a Natural H eritage Trust Fund project that our Queensland Branch and the Sunshine Coast Environment Council canied out. It includes a folder liill of water information, a suite of flyers and a resource kit fo r trainers. C lare Porter (cp orter@awa.asn.au) in our office in Artannon is busy managing this proj ect and the m.anual will be out very soon.

Another step is to read a book like Watershed, whi ch spells out the big issues and the alternative points of view. Every organisation with a stake in water really should be using these resources or son1ething similar to ensure that their local community, from schoolchildren to adults, is getti ng more water literate.

Step two, and probably much tougher in some ways, is to really engage the community in a disc ussion about w hat's going to happen about water. Although the concepts have been around for a long time, there is still a reluctance (more in some jurisdictions than others) to let the community in on anything big until the real consideration has been completed. To paraphrase the old joke about voting in Australia, 11ote early a,1d vote eften, we should be observing the rule of co11s11lt early an.d co11s1ilt eften. The Global Water Partnership , (www.gwpforum.org) has some good material abo ut achieving integrated water resource management. It repeatedly insists 2

WATER OCTOBER 2001

Aquaphemera

Barry Norman

that solutions must be affordable and ' owned' by the community. The TAC R eport no. 4 (p 17) says, 'a participatory approach is tire 011ly 111ea,1s.for reaching longlasti11g co11se11sus and co1111no11 agreement'.

The paradigm that prevailed when I first graduated as a civil engineer was that the experts knew what had to be done and everyone else had to go along with it.

Probably some e ngineers still fee l comfortable in that mould, but the fac t is the world has moved on. Nothing m uch can happen these days unless stakeholders ha ve genuinely been engaged in the dialogu e, before any decisions have been taken. Nothing antagonises poorly resourced co mmunity groups and volunteer representatives more than knowing they are being patronised by debating somethi ng chat has been predeterm ined.

I know several people, at the cutting edge in this field, who wilJ be saying to themselves, has Nor111a11 lost the plot? This is all old hat!. True, it should be old hat, but it's a hat many project proponents have not yet tiied on. I hope AW A, with active input from the converted , can work towards a goal of having every water organisation switched onto community and school education and effective communi ty participation. We are poised to help this happen and there has never been a greater need fo r both initiatives.

Barr)' Norman

This is a wonderful exa mple of making data, w hich is very exp ensive to collect, archive and manage, readily accessible to eveiyone. It means the benefits from collecting the data w ill be increased many fold and hopefully w ill encourage more extensive collection of data, so that better resource management decisions can be made.

Unfortunately, data collection has dropped off over the last decade or so, as commercialisation and budget cuts have taken their tolJ. In addition, as collection agencies sought to recover costs, demands for data declined as a direc t consequence of the cost and the difficulty in gaining access to the data.

CANRI is a maj or step in changing all this. T he N SW Government sho uld be congratulated on their efforts. The web address is www.canri.nsw.gov.au.

Another good news story is the rebirth of the Australian H ydrographers Association (AHA). This group is critical for the monitoring of Australia's water resources and has rejuvenated itself after many years of declin e, largely as an indirect co nsequence of the commercialisation of the government groups who were responsible for collecting most of the data. Those wanting to help or be a part of the new order, can contact The Secretaty, AHA, cl- 14 Kosciusko Street, T rara lgo n , 3844 or visi t http:/ / hydrographers.SOmegs.com. T he AW A is ve ry keen to assist the Hydrographers in getting back to their former glory and in assisting them in continually improving our knowledge of this essential reso urce.

Ross Knee

GROUNDWATER AND SALINISATION

MAPPING AND UNDERSTANDING SALi NITV IN THE LANDSCAPE I Lambert, K Lawrie, C Pain Introduction Australia's landscapes are an cient and deeply wea there d , reflecting t h e continent's geological stability. T he term. regoli ch is used to describe the layer of soil, weath ered materials and transported sediments that occurs above fresh bedrock.

The regolith common ly exceeds a hundred metres th ick in low reli ef cou n try.

T he regolith is now kn own to be a criti cal ele ment in dryland salinity. It conta ins va riable conce ntrations of sa lts that can be prefere ntially leached and transported in relatively permeable zones.

The salts have built up in the regolith over lo ng periods (h undreds of thousands of years) from rainfall , salt- laden dust storms an d roc k weath eri n g. Fu rthermore, regolith properties co ntrol water infiltration into the landscape.

So, w hi le sa linity is usually o nly a proble m w hen it expresses itself at and near the surface, its ca uses li e deeper within the landscape. T he concept of a rising water table bringing salinity to the su rface is too simplistic - there are co1nmon ly signifi cant salt stores and late ral fl ows of water th ro ugh relatively permeable zones in the regolith, some tens o f hundreds of metres deep, with m ajor infiltrations into the landscape.

Significant recent initiatives Th e National Action Plan for Sali n ity and Water Quality (NA P), anno unced by th e Prim e Minister in October 2000, is th e first com pre hensive national strategy to address salinity and water quality proble ms. Th e Co m monweal t h has committed $700 mi!J ion to this initiative and is seeking matchi ng state and territory fu nding. Th e NAP includes a Salt Mapping an d M ana geme nt Sup p o rt Program, directed by the Bureau of Rural Sciences, w hich encompasses studies in selected salinised agricultural areas.

The importance accorded to regolith science, both for land management and mineral exploration appl ications, has been grow in g rapidly, but rego li th expertise is not yet widely available. M ost resides within the recently established Coope rative R esearc h Ce nt re for Landscape Environments and Mine ral Explora t ion (C R C LEME), w hi c h

conducts regolith studies, education and training. Salinity studies are to be a m ajor focus of CRC LEME, which brings together experts fro m: • AGSO - Geoscience Austral ia - th e national geosc ience agency; • Bureau of R u ral Sciences (BRS), within the Common wealth D epartment of Agricu lture, Fisheries and Forestry; • CSIRO ; • SA D epartment of Primary Industries and R..eso urces; • NSW Department of Min e r a l R esou rces; and • va rious uni versities - ANU, Ca nberra, Adela ide and Curtin .

CRC LEME is providing a range of stud ies and services u nd e r the Salt M appi ng and Manage m e nt Su pport P rogram .

AGSO ( Geoscience Australia has been developing risk models fo r geological hazards (particularly landslides, earthquakes and fl oodin g) and conducting studi es of the risks th ese pose for selected urban centres. It is interested in expandin g these studies to cover environm.ental risk assessments, includin g salini ty in regional cities.

What stu di es are planned?

A better understanding of the key facto rs leading to sa linity req ui res g at h e r i n g i nformation o n rego lich properties - particularly in so far as these con trol major groundwater flows and infiltration zo n es - fr om fi eld and laboratory studi es. Targeted drill ing is needed to confi rm interpretations, and the n ew information should be integrated w ith other geologica l informat ion, including locati ons of fractures and ridges in bedrock w hich can foc us gro undwater flows.

Th e Sale M apping and M anagement Supp o rt Program includes d etail ed airborne surveys and co mplementary grou nd-based regolith studies in carefu!Jy selected areas where there is a sign ificant salin ity hazard. D etailed studies of priority areas will be integra ted with och er available information to draw conclusions on salinity so urces, mi gration paths and sinks throughou t each catchment, thereby underpinn ing catchm ent managem ent plans. As app rop riat e, geop h ys ica l

technologies to be used for sale mapping w ill encompass: • airborne electromagnetic (AEM) surveys • airborne magn etic surveys • airborne gamma-ray (rad iometric) surveys T o be e ffect i ve, ca t chme nt managem ent plans have to e ncompass salinity issues related to both agri cultu ral lands and regional cen tres. Regional centres contribute salinity by land clearing, engineering works, water supply and discharge or reuse of sewage effiuent.

These can resu lt in bui ld- ups of sa linity in and around regional cities, with consequent damage to infrastru cture and ho using.

Geophysical su rveys are oflimited use in built areas because of ' in terference' from infrastru cture. For regional centres, inform ation on sabnity migration and sinks w ill need to come from: • local regobth mapping supplemented by confi rmatory drill ing at selected sites; and • extrapola tio n fr om studi es in the su rround ing catchm ent.

Ri sk assessment studies can also help guide sali nity managemen t in regional citi es. Suc h studi es address potential infrastructure and soci al impacts, and costb e n e fi c m ode lli n g . Surveys u sin g h and-held co mp u ters with gl o b al positioning systems fo r direct entry o f data o n salinity impacts need to be interpreted in the li gh t of releva nt data on salinity processes.

It is important that all data and informatio n relevant to salin ity in a given catchment be captu red syste maticalJy in a geographic information system to faci litate integration and decision m aking .

The Authors Drs Ian Lambert, Ken Lawrie and Colin Pain are all geoscientists. Ian is G roup Manager, National Proj ects and Advice in AGSO(Geoscie nce Australia and spends 20 percent of his time in the Coope rative R esearc h Cent re for Landscape Environments and Mine ral Exploratio n (CR CLEME). Ken and Colin are also with Geoscience Australia, but work full time in C R CLE ME , where they are interim Program Leaders.

Contact lan. Lamberc@agso.gov.au WATER OCTOBER 2001

27

II

GROUNDWATER AND SALINISATION

AIRBORNE GEOPHYSICS: BETTER INFORMATION FOR LAND MANAGEMENT G Street 4. Airphotos 5.

Satellite data, [n areas of drylan d 6.

Airborne magneti c sa linit y a irborn e surveys geophysical data has been 7. Airborne radiometric p romoted as a new tool surveys for land management pl annin g . It mus t b e 8. Airborne electromagstressed however that the netic surveys geophysics itself will not 9 . Soils (whi ch can in part solve the problem and be derived from radio that appropriate metries) techn iques fo r extrac tion 10. Geology (Which can of the information from be derived from m agnetic the geophysical data are data) essential. These techniques 11. D rainage (derived from. can b e opt i m.i sed to DTM) deliver th e most suitable Figure 1. Airborne electromagnetic aircraft with loop strung around 12. Biodiversity data informatio n content from aircraft and receiver bird being deployed on cab le beneath. Normally 13. Water level data geophysics to land the bird trails some 100 m behind the aircraft (Street, 1995).

Some of these datasets managers. On a local scale The National Airborne Geophysics are already available. T his paper discusses geophysics can be used to map sa lt that airborne geophysical data and why it is a P roject (NAGP) completed in 1998 may impact on roads and oth er infrasdemonstrated the application of this valuable resource for land management tructure; choose optimum sites for dams; technology for salinity. Th e Minister for planning in rural areas. locate areas of high recharge close to Forests and Conservation has dubbed towns and map groundwater contamiSalinity these systems "the U ltrasound of the nation . In agricultural areas airborne Earth".

Salinity of agricu ltural land is a major geophysics can assist land managers to map en vironmental probl em in mu ch of T he airborne geophysical su rveys only soils in detail ; map areas of highest salt provide the basic data. T he interpretation Australia's cropping areas. The salinity is storage; and assess potential salt hazards as of the data yields information about often caused by rising watertables remobilwell as locating the most promising areas subsu rface processes, which can improve for bore establishment. ising and bringing to the surfa ce salts our knowledge about salinity causes. In stored in the regolith (weathered laye rs Introduction common with medical system s such as Xbetween surface and basement rock). rays and Ultrasound some interpretation Over the past ten years developments Salinity is a hydrogeological problem. of the data is obvious but detailed underin airborne geophysics have m ade these Local and regional ca uses of saline areas standing comes from. experience and instruments more applicable for land are often closely related to geology in the understanding of the technology involved management. Using geophysical instru sub-surface. Remedial measures based on plus in form ation obtained from co mple111.ents m ou nted in aircraft we can now the visual assessm.ent of surface salinity m entary datasets. T here are at least two rapidly: often fail because they do not address the stages to such an interpretation w hether 1. M ap sub-surface salt content in three causes. It is essential therefore to get some it is for a broken arm or potentially saline dimensions; understandi ng of subsurface structures, salt land .

2. M ap soils to incorporate detail not distribution and groundwater processes in 1. I can understand the problem previously possible; order to be able to predict and control 2.

I can see how to fix it 3. Locate areas of p o tential fresh and or groundwater rise and surface salini ty .

The existence of good geospatial data saline w ater resources; Traditionally groundwater has been coveLing agricultural areas should be a goal 4. Map geology in detail and determine mapped using drilJholes . However the for all governments in Australia. These whi ch geological structures are important level of detail and th e large areas involved data should include : for salinity; and m eans that drilling alone cannot be cost 1. C limate effective in providing th is information . [n 5. [nterpre t the geophysics to show areas 111.ineral exploration geologist routinely use 2. Cadastre of potential salinity hazard and defin e the geophysics to map the areas between drillca uses; 3. Digital terrain models (DTM)

Abstract

30

WATER OCTOBER 2001

GROUNDWATER

AND

SALINISATION

holes . Th e geophysics can provide three-dim ens ional variati ons in the physical properties o f the sub-surface and th e dri ll holes can be used to explain these variations in m eaningfu l terms.

Gro u nd geophy si cs has been widely used in salinity utilising Geoni cs style EM 38 and EM31 m eters. H oweve r the co st of ground operations can be almost 10 times that of airborn e m eas urem e nts. In addition the airborne system s can co ll ect significa ntly mu ch larger data volumes in on board computers.

and thorium. (Th) wh ich occur naturally in the ground surfa ce . Th e gamma ray receiver measures the full radioactivity spectrum and the peak responses due to K, U and Th are separa ted and measured to give concentrations. K is usually between 0 and 3%, w hile T h and U are in parts per million. Th e radiometric signal comes predominantly from the top 30cm up to 2m below th e surface. Simple classification tec hn iques can be used to divide the data into separate Figure 2. Electrical Conductivity of the ground in the region 2 to classes which can th en be 6 metres below the surface from an airborne electromagnetic related to detailed soil inforsurvey. Area is around 10 km across (Street and Pracilio , 2000).

Geophysical Methods mation . Thu s the Airborne Electromagnetic Surveys constant frequ ency is emitted by a transrelationships of these isotopes ca n be used mitter coi l a nd seco ndary curre nts Th e conce p t of using ai rborn e to improve so il mapping (Fi gure 4) . detected by a receiver coil. Both coils are geoph ysics for land ma nage me nt in areas Airborne Magnetic Surveys m ounted in a rigid boo m-like bird prone to salin ity has been aro und for M agn e ti c surveys map the tota l w hi ch is towed below and beh ind the aro und 15 years . It was pioneered in magnetic field of the earth. The variations helico pter. These systems do not get th e Victo ria and WA in late 1980s with due to distribution of magnetic mineral resolution verti cally that ca n be obtain ed analogue mineral explo ration airborne content in the rocks can be used to map with th e n ewer tim e domain systems. electromagnetic (AEM) systems. In more geology. In sa linity geological stru ctures However they do not have some of th e recent years EM syste ms have imp roved are often impo rtant in causing groundassoc iated problems inheren t in the in resol ution due advances in digital water leve ls to rise or f.low preferentially. aircraft syste ms due to the asym me try of proc essing tec hno logy .

In the deeply weath ered Australian th e receiver and transmitter.

In fi xed-wing, time-do main AE M the regolith and soi ls may often landscape The use of these electro magnetic syste m s a n electromagnetic pulse is be closely related to the underlying syste ms is no t con fi ned to sa linity. emitted into the ground approximately geology.

Street and Enge l (1998) found Em e rson et n/ (1999) used a n airborne every 15 m illiseco nds. This pu lse causes that condu cti vity was higher upslope of electromagn etic system along with other seconda1y electric currents to f.low in the geological structu res wh ich weath ered to data to defin e the controls o n potential grou nd. The electromagn etic fie ld of clays.

In addition these lower permeabili ty leakage fro m a liquid waste disposal site these c urrents ca n b e measured by th e zones result in slower groundwater f.low near Syd ney (Figure 3). very sensi tive receiver w hich is towed in and in effect act as underground dams and the 'bird' be hind the aircraft (Figure 1).

Airborne Radiometric Surveys ri sin g watertables. A co mbinatio n of The measurem ents of seco ndaty field are The airborne radiometric sys te m electro magnetic data and magnetic ca n stacked (o r averaged) and a m easurem ent m easures ga mma radiation (or radioacassist in de termining whic h geological taken every 1. 2 m etres alo ng lin e. Thus ti vity) fro m natural sources. Some of this stru ctures are significant. Th e geological the receiver m easures th e decay o f a is due to cosmi c radi ation but significant units w hic h weather to clays are usuall y electromagnetic signal as in moves down amo unts are due to th e radioactive the volcanic rocks such as basalts, dole1ite, th rough the ground. T his entails som e isotopes of potassium (K), uran ium (U ) greenstones etc. These are more magnetic 1. 500 separate measurements and thus easy to map w ith wh ic h ca n th en be used to mod ern instrum en ts. determine th e conduc tivity In ad diti o n m agn e t ic relationships benea th the surveys ca n be used to map ground surface at that point. fau lt zones. These may be T hi s co ndu ct i v it y mo re perm.eab le and ca n relationship is best defined direct groundwater fl ow. In in the zone betwee n 5 and areas of fres he r water th e 50 metres below the surface fractu red rock alo ng fault (Figure 2). Ground conduczones can b e important tivi ty is related to the aq uifers for small-scale local amount of water in the supplies (Figure 5). ground, its salinity pl us am ount of cations available for elec tri cal condu ction fro m clay material.

In he li copte r sys tem s (w hi c h a r e m ostly frequency d omain) a

Digital Terrain Model

Figure 3. Conductivity data overlayed on a shaded magnetic image around a liquid waste disposal site near Sydney (Emerson et al,

1999).

In addition the airborn e surveys can pro duce a digital elevation m odel using th e data from radar altimeters and C PS . T he accuracy of WATER OCTOBER 2001

31

GROUNDWATER

AND

SALINISATION

these data is around 5 metres. They record a measurement every 60 m etres (Figure 6) .

Interpretation The airborne geophysical data is normally translated into 2D and m ore recently 3D image maps. It does not have the detail of point measurements made on the ground but it can be used to extend detailed point information over much larger areas. Thus radiometric data can be classified into areas with sim ilar radiometric response. T hese can be field checked for soil characteristics and a soil map produced. Because of the spa tial detail in radiometric maps soil scientists are now using the data to extend other point information about soil characteristics such as soil leakiness (recharge rates) under crops which can then be extended to nu trient loss and soil profitabili ty (Pracilio and Cook, 2001) .

Airborne electromagnetic data maps the salt in the ground. H owever the presence of high salt in itself may not be a problem. Thus it is n ecessary to build up a model of how salt and water may interact with t h e s urroundin g environment including soils (from radiom etri c data), topography (from DTM), geology (from magnetic data), surface drainage (from DTM or airphotos) etc.

The pro cess of interpreting salt hazard sites or sites of po tential saline groundwater discharge was developed in the Broomehill Project in WA and refined under the National Airborne Geophysics Project (Street and Pracilio, 2000).

Figure 4. Radiometric ternary image (K=red; Th=green; U=blue) on left which has been used to create detailed soils map on the right . Some information is lost in the process particularly in regard to gradational boundaries. It is very difficult to map this level of detail using airphoto interpretation and field traverses (Street and Praci lio, 2000).

Individual landowners would then create fi les fo r their properties and access them at home using public domain software. Easily accessible digital datasets such as airborne geophysics datasets covering shires and the interpretation of such data would form the base data in such a project.

Conclusion

fa rm level. This p aper foc uses on airbo rne geop hysics as basic biophysical dataset that shou ld be available for land m anagem ent.

O n a local scale geophysics can be used to : • Map salt beneath roads and allow better forward planning for road maintenance • Locate potential areas of saline groundwater discharge • Choose optimu m sites for dams for local water su pply • Locate areas of high recharge close to towns.

• Map groundwater contamination I n agricu l tu r al a r eas air b or n e geophysics can assist land managers to : • Map soils in detail not previously possible • Locate areas of greatest likely nutrien t loss • Map areas of h ighest salt storage • Assess potential salt hazards T h us the ex istence o f g o o d geophysical datasets over a rural areas

Geographic Information Systems

T he advantage of having detailed geospatial data covering agricultural areas is the ability to make betterinformed decisions in land management.

Ensuring that the basic biophysical data sets are available for landowners is one way in which governments can assist in reversing the spread of salinity. State and federal governm.ents ha ve fo r ma ny years fund ed program s to collect and make available regional data such as topographic m aps, airphotos and satellite data. The collection of geophysical data has also been provided as a m eans of assisting the mineral exploration industty.

However much of this data has been vety regional and has limited use at shire to

Whil e most spa tial data can be created in map form, more information can be gained wh en it is used with complementary datasets in Geographic Informatio n Systems. T h e cost of purchasing G!S software may be too high fo r individual lan down ers o r land managers. Co uncils an d catc hm ent groups should consider purchasing a license and creating a GIS database in a cen tral location w hi ch can be booked and used by individuals.

Managem ent of this reso urce needs to be carefull y controlled to ensure the quality of d~ta on such a database is not compro mised. Guidelines shou ld be established and a database m anager appointed or a co nsultant used to manage the database externally. Extranet facilities provided by a consulting group could also be an option for database management.

Figure 5. Magnetic data enhanced with a first vertical derivative filter (left) and a simplified interpreted geology on right. Red are greenst one belts which weath er to clays and are likely to be barriers to groundwater flow. Ye llow are various basalt un its which often have an inter-flow weathered zone which can act as an aquifer.

Blue are more recent channel deposits probably laid down in creek channels and likely to be more perm eable to groundwater flow. The area is near Willaura in Victoria and covers 22,000 hectares (Street et al, 1998a).

32

WATER OCTOBER 2001

GROUNDWATER

AND

SALINISATION

Figure 6. Radiometric data overlayed on digital terra in model. Both datasets were derived f rom the airborne geophysical survey. Area is around 10,000 hectares (Courtesy UTS Geophysics). Some relationships bet ween topography and radiom etries wh ich relate to soil type changes are obvious. sho uld put it at an advantage to its neighbo urs in assistin g land managers to add ress salinity early Thus informatio n from geophysics can be used to : • D evelop remedial strategies that specifically address salinity; and • D evelop guidelin es for bu ilding etc dependent upon sal inity hazard • As a regional datase t use the geophysics co develop co o rdinated ap proac hes between ocher autho riti es. T hus governments should consider maki ng funds available co collect regional geophysical surveys in agricultural areas to allow land man agers to make b etter informed decisions. The precedent of supplying such information to mineral exploration companies has already been set.. The p rovision of a central GIS facility loaded with available digital data is a first step in rural areas in the development of a coordinated approach co salinity .

Management Centre NSW - An airbo rne electromagnetic study. Preview Australian Society of Explo ration G eophysicists.

Nulsen R A, Beeston G, Smith R , and Street G. 1995. Delivering a technically sound basis fo r c atchme nt a n d fa rm p la nning.

Proceedings W AL!S Forum '96 Perth WA. Pracilio G, and Cook S. 2001. Estimating the spatial distributio n of catch ment leakiness under cropping within a Western Australian catchment. Proceedings of Salinity, Land M an a geme nt and N ew T ec hn o logy Conference/ W orkshop, Bendigo 2001 . Aust.

Soc. of Exploration Ge ophysicists.

Pracilio G, Street GJ , N allan Chakravatula P, Nash C, O wers M , Triggs D, and Lane R .

19986. National D ryland Salinity program.

Airbo rne Geophysical Surveys to assist in planning fo r sali nity control - 3. Lake Toolibin SALTMAP Survey - Interpretation R epo rt - December 1998. (1 10 pages, plus appendices and maps.)

Street G 1995. SALTMAP: A sound technical basis for catchment and farm planning.

Proceedings 37th Australian Surveyors C onference. Perth WA .

Street G J , & Engel R 1987. T he use of ge ophysics in defining the causes of dryland salinity in sou t h - w es te rn Au str ali a .

Exploratio n G eophysics 18, 207-210.

Street GJ, Pracilio G , Owers M , Triggs D , and Lane R . 1998a. Natio nal D ryland Salinity program. Airborne Geophysical Surveys to assist in planning for salinity control - 1.

Willaura SALTMAP Survey - Interpretation R eport - June 1998 . (92 pages, plus appe ndices and maps.)

Street G., and Pracilio G 2000, Catchment reinterpretatio n T oolibin Lake. Project fo r Conservation and Land Management WA.

Thiess Services is supported by an innovative network of technical and human resources.

Professionals in the provision of municipal and infrastructure services, we offer: - Infrastructure maintenance seNices for water and sewerage reticulation systems;

The Author Dr . Greg Street i s S e nior Geo physicist with Sinclair Kn ight Merz Pcy Led, PO Box H615, Perch W estern Australia, 6001 , and a part- time lecturer and PhD student at the C urtin Universiry o f T ec h nology, B e ntl e y , WA. Gstre ec@skm.com.au

- Drainage maintenance seNices; - Wastewater t reatment seNices; and - Hydrographic seNices.

References Engel R , Mcf arlane D , and Street GJ , 1987. The influence of dolerite dykes o n saline seeps in south- western Australia. Aust J Soil R es 25 , 125- 136.

Emerson DW, Street G . D o broletj ,. Yang YP and Macnae J C. 1999. The conductive en vironment of the C astlereagh Waste

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GROUNDWATER AND SALINISATION

ml

A FRACTURED ROCK AQUIFER: THE CLARE VALLEY PROJECT P Cook, A Love Abstract The fractured rock aquifers in the C lare Valley of South Australia (Figure 1) have been extensively researched over the past four years. T he work has provided estimates of groundwater flu xes which will ensu re sustainable development of the expanding wine industry and protection o f the e n v ir on m e nt. The proj ec t has developed new tec h niques for estimating aquifer recharge rates and horizontal and vertical flow. These new methods have already been adopted by other fra ctured rock investigations throughout Australia.

T his paper presents some of the main findings of the study.

Integrated Model R esults from the C lare Valley study are discussed in reference to an integrated catchment model. Figure 2 is a schematic representation of this model showing the n1ain compo nents of the groundwater budget.

Aquifer Characteristics Groundwater in the Clare Valley resides in fractu red rock aquifers which were formed 600- 800 million Figure 1. Location of the Clare Va lley research years ago. Major rock units are sites. siltstone, shale, sandstone and quartzite.

The movement of groundwater predominantly occurs through fractures and joints, w hich occur throughout the region. The u n-fractured rock acts as a storage reservoir for imm.obile groundwater and salt.

Hydraulic testing has indicated that the aquifer can be divided into two broad zones: a relatively perm eable zone in the upper 20-40 m, and a deeper, lowpermeability regional zone. Fracture mapping of rock exposed at the surface and drill core indicate that fractures are closely spaced (generally less that 1 m ) in the upper zone. The movem ent of Figure 2. Conceptual block diagram of water depends upon not onJy the fracture groundwater flow systems in the Clare spacing, but also on their size and Valley. R denotes groundwater recharge, Q co nnection. The size of the fractures tends to decrease with depth. Wei] testing is horizontal flow for the upper system, B is bas indicated that hydraulic conductivity groundwater baseflow to creeks, q is varies by many orders o f magnitude, but horizontal f low for the lower flow system and r denotes minimal connection between generally decreases with depth. The deeper flow system becomes progressively the upper and lower flow systems.

34

WATER OCTOBER 2001

isolated fro m the upper system due to a decrease in fract ure density.

Groundwater salinity in the Glare Valley is highly variable ranging from 500 mg/L to 7000 mg/L. The upper flow system often has better quality water, which becomes more saline w ith increasing d epth. We have measured groundwater salinity stored in the rock matrix from leaching experim ents to be in excess of 10,000 mg/L. This high sali nity water in the rock has the potential to mix with the more mobile water in the fractures.

Recharge Prior to the clearance of nati ve vegetation, grou ndwater rec harge rates in many parts of Australia were much lower than th ey are today. W e ha ve es timated the p re-clearin g rec harge rate in the Clare Valley to be < 5 mm/yr from chloride mass balance methods. This is due to a greater proportion of annual rainfall being utilised by native vegetation compared with current land use. As a result of lower recharge rates, the recharge water was m ore saline pre-clearing.

Groundwater wells throughout the C lare Valley show large seasonal fluctuations in water level, indicating that som e recharge occurs in most years.

Estimating the magnitude ofinclividual rec harge eve nts from w ater tabl e responses to rain fall in fractured rocks is not possible w ithout a more detailed understanding of the properties of both the fractures and solid rock, than is possible to obtain.

In this study we have obtained estimates of recharge rates at Pearce Road and Wendouree sites using a combination of aquifer properties and groundwater dating with a suite of environmental tracers (chlorine-36, carbon-14, chlorofluoro carbons (CFC's) and tritium) . At each site recharge rates were determined to be in the range 50-75 111111/yr. In other areas of the Clare Valley, where mean annual rainfall is less, we would expect lower rates of annua l recharge .

Groundwater dating has also revealed rapid chan ges in grou ndwater age over short vertical distances in the aquifer.

GROUNDWATER

3H (TU)

0 20 40 60 80 100 0

0.5

SALINISATION

This suggests that the upper and lo wer flo w systems are relatively isolated from each o ther (Figure 3) .

Groundwater Dating 14c (%MC)

AND

1.5

2

0

Horizontal Flow

Identi fying flow systems and rates of ho ri zontal flo w is notoriously I difficult in fractured rock aquifers, as I m ost o f th e underground flow 40 occurs in a small section of th e :[ geological fo rmatio n. The proj ec t £0. 60 I Q) team ha s d ev elo p ed tw o n ew a I techniqu es (well dilution and R adon) 80 I for lo cating the maj o r flo w zones as well as providing es timates o f 100 ho rizontal flow rates.

200911-003 Figure 4 is an example of the well 120 dilution method at the W endo uree Figure 3. Results of groundwater dating fi eld site. As can be seen , under natural from piezometers at Wendouree Winery. conditions, Electri cal Conducti vity (E C, The presence of Tritium (3 H) and a measurement of sa linity) increases w ith Carbon14 (14C) > 70% MC indicates that depth in the well. Th e EC increases in a water must be less tha n 50years old. step-like manner at 38 m and 70 m (solid Relative ly high concentrations of both blu e line) . These rapid in creases in EC at 3 H and 1 4 C in th e top 40 m indicates th ese locatio ns represe nt large fractures rapid movement of wat er to this depth . intersecting the well. In order to determine Decreased concentrations below 40 m how fast water is moving through the well, indicates red uced movement of water we mixed th e well column and observed the changes in the E C profile over time. and isolation of the upper and lowerflow zones.

Th e well was mixed by placing a pump I

I

20

at approximately 90 m and circulating salty water fro m this depth into the to p o f th e we ll. Th e mixed profile is m onito red at different times as it re-equilibrates. The time that it takes fo r th e mixed profile to return to the original profile is proportional to the flow rate. A striking feature o f the mixed profile is the distin ctive troughs in th e upper part o f the well. T hese troughs represent the location of active hydrauli c fractures where th e m.ixed profile has been diluted w ith lower salinity water from the aqu ife r.

Horizontal flow rates ln the upp er 38 m o f the well are clearly much higher than flo w rates deeper in the well, reflecting the two general zones of groundwater flo w .

Flow rates estimated from this method range over four orders of magnitude fro m 1 mm / day to 10 m / day througho ut the well column.

T he radon meth o d is based o n the differ en ce b etwee n di sso lved radon co nce ntrations in th e w ell 111.easured befo re and after pumping. R ado n is gen erated from th e decay of uranium within the aquifer matrix, and so is naturally present in all groundwaters. It has a hal f life o f 3 .8 days. If the flow rate through the well is very low, then the

Electrical Conductivity (mS/cm)

01

2

3

4

5

6

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Figure 4. Results of the Well Dilution experiment at Wendouree winery for May 2000. The solid dark line (C 00) is the measured concentration in the we ll before mixing and Co (broken green line) represents the concentration immediately after mixing. The th in dashed lines represent the different monitoring times . while the arrow denotes increasing time since the we ll was initially mixed.

Phone HARALD BECKER on 02 97 48 1788 or fax your inquiry to 02 97 48 1878 REHAU Pty Ltd, 91 Derby Street, SILVERWATER NSW 2128 WATER OCTOBER 2001

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GROUNDWATER

water m the well w ill be stagnant, and most o f its radon w ould have decayed to zero. Significan t rado n concentrations sho uld be present in w ell water only if there is sufficient flow into the well to replenish the radon fas ter than it can decay. C omparing the radon concentrations at a particular d epth b efo r e an d aft e r pumping, enables estimates of the ho rizontal flo w rate.

T he range of groundwater flow rates obtained using this approach was w ithin the range of those obtained using the well dilution m ethod .

AND

SALINISATION

Maximum groundwater discharge rate is the total streamflow rate when aquifer water levels are highest

"Cl

: -: ,!!

¡§. <

Minimum groundwater discharge is a percentage of streamflow rate (0% in this case) when aquifer water levels are the lowest

Discharge to streams

Jan

Feb

Mar

Apr

May

Jun

Jul

Sep

Oct

Nov

Dec

Figure 5 . Schematic representation of the mode l used t o determine annual groundwater discharge to st reams. In this example, at the t ime of minimum and maximum groundwater discharge rates, there is 0% and 100% groundwater in t he st ream respectively.

Summary

Discharge to Streams All streams in the C lare Valley are ephem eral and only flow for three to fo u r months each year. Stream flo w comprises surface w ater ru n- off and baseflow from grou ndwater. W e have used a surface water-gro undwater chloride mass balance m e thod to sho w that groundwa te r

PACIFIC

discharge to the Eyre C reek is < 10 mm/year. W e have also develop ed a me th o d of estimati ng gro u ndwate r d isc harge to strea m s, w hic h utilises seasonal fl uctuations in aqui fe r wa ter level data to separate stream fl ow data. The general approach in Figure 5, assumes that the groundwater d ischa rge rate into stream.s is greatest when aquifer water

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WATER OCTOBER 2001

levels are highest and equal to the total stream flo w at that time of the year.

Minimum gr o u ndw ater discharge rates occur when aquifer w ater levels are lowest and the rate is 20 to 40% of the stream flo w at th a t tim e (a ltho u g h c urr e n t p robl e m s associated with recording high stream flow events n1ay r es u l t in hi gh e r values) . R esults obtained using thi s approach were co mp ara bl e t o t h ose obtained using chlo ride mass balance.

We have obtained estimates of groundwater flow velocity, recharge rates and grou ndwa ter disc harge to streams using a nu mber of established and new m ethods.

M ean annual rec ha rge rate has been estimated to be up to 50- 75 nm1/yr at tw o sites, however these values maybe lower in areas of lower m ean ann ual rain fall and diffe r e n t so il a nd land - u se ty p es .

Grou ndwater discharge to creeks has been estimated to be less than 10 mm/yr in the Lyre C reek catc hment . C urrent gro undwa ter extraction for irrigatio n is less than 10 mm/yr over the entire C lare Valley.

Th e rem aining 30 to 33-m m recharge leaves the C lare Valley as lateral groundwa ter flo w .

Acknowledgments T h is proj ect was fu nded by major c ontrib u ti o n s from t h e R esource Assessment Divisio n of the D epartment fo r Wate r R esources (fo rme rly P IRSA , Groundwater Services) and Land and Wa ter Australia (fo rm erly Land and Wa t e r R es ources R e se a r c h and D evelopment Corporation). W e gratefu lly ack nowledge the contribu tion fr o m overseas sc ientists who participated in vario us com ponen ts of this proj ect : Dr Rip Solomo n (Un iversity of Utah), Dr.Todd H alihan (U niversity of Texas) and D r Bill Sanfo rd (Colorado State University); Flinders University of Sou th Australia and the Viticultural lndustty have provided additional support.

The Authors Dr Peter Cook is a hydro geologist w ith CS IRO Land and Wa ter, Glen Os m o nd , SA. E m a il Pe t er. Co ok@ adl. clw.csiro.au . Andrew Love works fo r th e South Australian D epartmen t of W ater R eso urces, R esource Assess ment, R esearch and D evelopment Gro up .

II

GROUNDWATER AND SALINISATION

SALINITY ASSESSMENT WITH HARSD: LITTLE RIVER CATCHMENT, NSW S W Davies, D Pollock, W A Milne-Home, R B Salama Abstract T h e HA R. SD m e th o d (H y d ro geomorphic Analysis o f R egional Spacial D ata) was applied for salin ity assessm ent of the 1,075 krn 2 Little River Catchment, M acq uarie Valley, NSW. Au tomated terrain classificatio n was performed using a 25 111 resolution Digital Elevation M odel (D E M ) and p o te ntial gro und wate r disch arge sites were identifi ed fro m a regio nal-scale hydrau li c h ead surface (H H S) co nstru c te d fro m spa rselydistributed boreh o le data using GIS and hyd ro logic t ec h niq ue s. These sites co mp ared fav o urab ly w ith m ap p ed sali nity in the southern area, but less so elsew h e re . T ran smissivity, spatiall y distribu ted recharge and the H H S fo rmed in pu t to Flown et An alysis Software (FAS) , a steady-state groundwater model asso ciated with HARSD , to pro vide pr e lim in ary g r ou n dw ate r and, b y in feren ce, sa lt fl ux estimates fo r the 735 km 2 Buckinbah C reek subcatchm ent.

Phase-II w ork will investigate salinity in a h igh - risk subcatc hment o f Buckinbah C ree k , usin g h ydrologica l, h ydro ecological and rem.ote sensing techniques.

Introduction Salinity is now recognised as o ne o f th e m o st p ervasive and po tentiall y damaging p ro blems threa tening ri ve rine an d terrestri al environments throu gh out the Murray Darling Basin (MDB) . The severi ty and scale of th e problem is do cum.ented in recent fi ndings fro m both th e M urray Darling Basin Ministerial Cou nci l's Salinity Audit (MDBMC, 1999) and a report to the Prime Minister's Scien ce En gin eerin g and Innovatio n Coun cil (PM SEIC, 1999) . T h e Audit iden tifies the M acq uarie, B ogan and Castler eagh regio ns o f Central W est N SW as high-risk areas and foc uses, in part, o n the Little R iver and T albragar catc h1nents of the upper Macqu arie Vall ey w here salini ry is particu larly seve re . T h e Central W est Catchment Managem ent Co mmittee (CW C M C) T his paper was presented at the 8th M urray Darling Basin Groundwater Workshop, 4-6 September, 2001, Victor Harbour, SA.

recognises the impo rtance of salinity in t he r egion a n d in 19 9 8 a jo in t commitment to develop a planning framework fo r the future management of sa lini ty was esta bl ish e d w it h th e D e p a rtm e n t o f L an d and W at e r C o nservation (DLWC) .

T h e curre nt study was initi ated through DLW C Proj ect H ydrological Actionsfor Ce11tral 1-1/est Com1111111ity Salinity Pla1111ing1 . Partners in the proj ect include the DLWC - C entral W est R egion, the Littl e Ri ve r L a nd ca r e S t ee r i n g C ommittee and the N atio nal C entre for G roundwater M anagement, University of T echnology, Sydn ey. Th e study ex tends the sco pe of p revio us work in the area by applying HARSD , a G IS-based m eth od fo r H ydrogeo mo rphic Analysis o f R egional Spacial Data. T he principal aim o f th e study was to develop a regional-scale groundw ater m odel with reliable predictive cap abili ty. T he model will assist land and resource managers in the selection and siting of appropriate managem ent op tions d esigned co lower grou ndwater levels and opti mise the benefits of expenditure during remed iati on and preventio n of d ryland salinity in the regio n.

Background to HARSD T h e H AR S D p ro ce dure s we re develo ped by Salama and co lleagues (Salama et al., 1999), CS IRO, Lan d and W ate r, Perth, WA fo llowin g recent ad v an ce m e n ts i n Geo gr ap h i ca l Information Systems (G IS). HARSD is a suite of methods and m odels designed to provide hydrogeological in ferences for small and large catchments. In general, it uses param eters develo ped fr om spatial and tempo ral G IS datase ts co model landuse scenarios aimed at controll ing sali nity (Salama et al. , 1997). H ARSD comprises a suite of three main procedures (Salam a et al., l 996) inco rporati ng: • A11 to111ate d T errai 11 Classificat io11 (H ydrogeomorphic C lassifi cation) of Catc hmen ts. This step involves th e d e ri va ti o n o f prim a ry to po grap h ic attributes fro m a hi gh resolution DEM, statistical and graphi cal analysis o f these va r i a bl es a nd c l ass ifi ca tio n o f Hydrogeomorphic Units (H GU' s), or

do mains w hich are expected to operate u niqu ely and have similar aquifer p rop e rt ies and r ec h a rge/ d isc h ar ge behavio ur.

• Generatio11 of a H ydraulic H ead Suiface (HHS) that uses two alternative hydroge ologica l tec h niq u es. In t he fi rst technique a least-squares regression is derived between the reduced water leve ls and sur fa ce el ev ati on. T h e developed regressio ns are then used in a GIS en vironment to prep are water level maps. In the second techniqu e a land unit classification based on the hyd rogeomorph ic characteristics of the catch men t is used to de fin e th e depth to wa ter in each zone using regressio n. The H HS can also be used to identi fy potential groundw ater discharge sites.

• Flownet Analysis Seftware (FAS), a steady-state gro undwater m o del that r eq ui res inp u t fr o m tran smiss ivi ty es ti mates, spatia!Jy distributed recharge and the H H S co derive grou ndwater flux and, by associatio n, sa lt fl ux. T he flownet ca n also mod el gro undwate r level response to various climatic or landuse change.

The H ARSD m ethod uses geomo rphological theory and experience to infer spatial codependen ce am on g aquife r parameters and oth er controls on grou ndwater be haviour. T he approa ch asserts chat, at least in erosional landscapes, surface topography reflec ts th e spatial c o ev o l ucio n o f t he se p r o p e rti es .

Co mb in ed wi t h some h ydro logical understandin g and even very sparse hydrol ogical data, the techniqu e offers a more effi cient, obj ective and constrained p a ra m e ce r isa tio n t ha n cont inuum mechanics-based gro undwater m odels.

T he H AR.SD pro cedure maintains chat th e shape o f a landscape is a fu nction of climate and geology, resu ltin g in slopes w hich, together with geology, control the movement o f groundwater through their mutual influ ence on transmissiviry and hydraulic gradient. The resulting HHS is largely a subdu ed and smooched reflection of topography (Salama et al., 1996a).

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WATER OCTO BER 2001

37

GROUNDWATER

AND

SALINISATION

The mean elevation is 447 m.

The terrain is characterised by undu lating and hilly landform N with break of slope features developed at all elevations.

The mean and maximum slopes in the study area are 3° and 36° respectively.

Hydrology: The area is largely drained by th e maj or, northward- flowing Buck.inbah Creek. This system drains into Little River which enters the M acquarie River at the O 5 ,o-. northern end of the study area at a point downstrea m fron1 ~~ Wellington and upst rea m. from Dubbo, Narromine and the environmentally significant M acquarie Marshes. Previous 700000 workers have identified local and intermediate (fractureFigure 1 . Location of Little River Study Catchment controlled) flow systems in the area and establi shed that groundwater mixing between the two HARSD technology was successfully applied to the Axe Creek Catchment, regimes is restricted (Callan , 1995 and Victoria (Salama et al., 1997). The Kazemi, 1999) . geology of Axe Creek is similar to Little Landuse : Primary landuse typ es in the River and the study is regarded as an study area are dominated by mixed appropriate comparison. Water level pasture (61 %) and cropping (34%) . maps generated by HARSD were used Timber covers a total area of -5% and to map flow regimes, delineate areas of contribu tes to a very high Landuse groundwater recharge, transmission and H azard Rating (Humphries, 2000). discharge and simulate the impact on Slope Hazard: T he study area has a high groundwater discharge under different Slope Hazard R ating and is typified by land management options. Other studies major elevation and slope variation, include those for th e Upper Kent River medium to high energy drainage lines and Catchment, Western Australia (Salam.a et significant break of slope formations. A al., 1997a) and the Leddon and Campaspe slop e ca tegory/land capability m ap catchments, northern Victoria (Salama et produced for Little River shows hi gher al., 1999a) . angle slopes asso ciated mainly with Catchment Description intrusive rocks.

Erosion and Salt Occurrences: The Location: The 1,075 km 2 Little River Little River area has a very high Salinity study catchment is situated on the H azard Rating (Humph ries, 2000) lower-western flanks of the Great reflecting a large salt store in the Dividing Range in the central-eastern landscape, a high recharge potential from portion of the MDB. The area is located highly complex rocks and a landscape in the Upper Macquarie Valley, Central W est Catchment, N SW (Fig. 1). which promotes salinisation at su rface.

H umphries (2000) estimates that the total Climate: The area has a temperate area affected by salinity in the catchment climate with four well defined seasons. has increased 24% from 1,200 ha to 5,000 The annual m ean minimum and ha in the past ten years. Over 42% of the maximum temperatures are 10.4 and 22.5° C respectively. The mean annual study area is affected by erosion. Sheet rainfall (604 111111) is evenly distributed erosion is the most widespread rype with throughout the year, however slightly a surface expression of 448 km2 . more rain falls from O ctob er to January.

Geology: The Little River study area Rainfall and evaporation data infer that occurs within th e northeastern portion recharge is maximised in June and July. of the Lachlan Orogen, a composite General Morphology: The catchment Orogenic Belt that developed during the is elongated N-S wit h maximum Palaeozoic Era on the eastern margin of orthogonal dimensions of 72 x 26 km. th e Australian Plate. This Orogen is one Local relief ranges from 265 111 ASL in of the most complex geological systems th e north to 740 m ASL in the south . associated wi th dryl a nd sa linit y .

A

I

i

-~=~ /;;;;

38

WATER OCTOBER 2001

•ORANGE

Stratigraphic sequences in the Orogen have sustained several deformation events resulting in the formation of meridional structural packages rypified by intense folding and multiple thrust sheets. The intense fracturi ng has promoted the development of salinity and resulted in the study area being assigned with a very high Geological Complexity rati ng (Humphries, 2000). The geology of the Little River area is detailed in the Dubbo 1:250,000 Explanatory Notes (AGSO, 1999) and summarised in Davies (200 1).

Local lithologies range in age from Mid Ordovician to the Cainozoic. M afic to felsic volcano-sedim.entary Formations of Late Ordovician to D evo nian age dominate the central and eastern parts of the study area and include the significant Canowindra Volcanics. These rocks typically occur as broad, prom inent strike ridges that extend for over 60 km.

This Fo rmation is host to several saline sites, many of them preferentialJy localised along contact zones (Nicholson , 1996).

The area to the west is intruded by composite calc-alkaline plutons of the Early D evonian Yeoval Batholith .

Componen ts of the P ermo-Triassic Gunnedah Basin onlap D evonian Gregra Group rocks in the northwest.

T he area has a very high Salt Source Potential of Lithology rating (H umphries, 2000) based on the conducive properties of the rocks to produce and concentrate salts. T his rating also reflects the high proportion of sediments with a marine origin, rock geochemistry and the strong weathering tendency of volcanic rocks and coarse-grained, porp hyritic and felspathic igneous rocks. The catchment has a high Soil Permeability rating due to the dominance of non-sodic duplex clay loam soils.

Results Hydrogeomorphic Classification

A GIS-based approach was used to classify the landscape of the Little River stu dy area into Hydrogeomorphic U nits (HGU 's). This was achieve d using automated terrain classification involving the derivation of topographic attributes (e.g., slope, break of slop e, minimum slope, aspect, profile curvature and plan curvature) from the DEM, statistical and graphical analysis of these variables and map overlay using lithology and soil outlines. Four HGU 's were initially defin ed on the basis of elevation using conventional standard deviation breaks.

Slope was also incorporated into the landscape disaggregation process as it showed a close spatial relationship with

GROUNDWATER lithology, yet m aintained its independence from elevation . The slope grid was reclassified by applying a < or > the m ean slope (2.96°) condition and amalgan1ated w ith the reclassified elevation grid to produce eight H GU's.

• Pw = Z - (k*S) Equation 6.4 (Salama et al. , 1996)

Where: Pw = Local hydrau lic h ead elevation Z Surface Elevati o n Minimum Slope S k A constant deri ved by cal.ibration with th e o bserved standing wate r level (SWL) in bo res Th e co nstant 'k ' was de rived from ele va ti on and observed bore water levels by rearranging th e above formu la to:

SALINISATION

Table 1. Regression results used to generate the regional groundwater surface at Little River from SWL Elevation v's Surface Elevation for Minimum Slope Classes (DLWC data, Pipe-1 data, 1920 to 2000, Major Spikes Removed).

M inimum Slope Category General Morphology

Prediction of the Hydraulic Head Surface (HHS)

Th e regional HHS for Little R.iver was constru c ted usi ng G IS and hydrological methods on sparse, irregularly-distributed , pip e-1 groundwater level data , obse rved in bores penetrating surficial aquifers, ex tra c te d from th e c urre nt DLWC (Dubbo) bore ho le database. The primary dataset represents an 80 year observation period from 1920 to 2000. All de rived topographi c variab les were attributed to bore points in G IS . Linear regression analysis was selected in prefere n ce to the HGU approach for HHS co nstruction du e to insuffi cient bore hole data with in several H GU's. The relationship between elevation , slope and water level was investigated using:

AND

R-Squared

Linear Regression Formula

0.00 - 0.09*

Morass

0.9975

y = 1.1027 (X) - 13.151

0.09 - 0.19

Flats - 1

0.7525

y = 0.9440 (x) + 5.0181

0.19 - 0.35

Flats - 2

0.9909

y = 1.0357 (X) - 21 .186

0.35 - 0.50

Flats - 3

0.9970

y = 1.0497 (x) - 24.571

0.50 - 0.80

V.Gently Inclined - 1

0.9978

y = 1.0016 (x) - 9.1459

0.80 - 1.11

V.Gently Inclined - 2

0.9939

y = 1.0108 (x) - 12.941

1 .11 - 2.00

Gently Inclined

0.9974

y = 0.9872 (X) - 2.7807

> 2.00

All steeper slopes

0.9966

(degrees)

y = 0.9888 (x) - 3.6822 (Where: y = HHS; x = elev. grid)

*This category has insufficient data for reliable regression. The R-squared value and formula used here is taken from the global regression performed on the combined minimum slope classes.

data) were identified at this stage and removed from th e primary database .

Linear regressions were developed for the eight minimum slope classes within th e 1 920 to 2000 dataset in addition to fi ve tempora l subsets using five regression types Th ese va ria tions w ere exa mined to d etermi ne the most appro priate time frame and best regression formu las to apply to the eleva tion grid during generation of the HHS. The parent, pi pe-1 , 1920 to 2000 (major spik es re mo ved) dataset was selected fo r HHS construction as lin ear regression resul ts fo r minim um slope classes within smaller temporal subsets were in man y cases affected by insuffi cien t data. Best regression results were obtained fro m this datase t using Bore SWL v's Surfa ce El eva tion .

Regression fo rmula s fo r indiv id ua l m inimum slope classes were then applied to the elevation grid to generate the HHS (T abl e 1). 1n a more ideal situ ati on, gro und water levels taken over a very short time fram e from a suffi cie nt

numbe r of strategica ll y distributed bores wo uld op timise results.

Satisfac tory res ults were obtained fr om linear regress io n s testing th e predicted HH S (at bore points) v's observed SWL's (r2 = 0.9) (Fig. 2).

R esults however, were less satisfacto1y fo r D epth to HHS v's D epth to B ore SWL. R esiduals were small fo r data from bores in areas of low slope, but showed increasing variation with increasing slop e.

Wh ile variabili ty was minimised within small er, more rece nt data subsets (e.g., 1990 to 2000), the trend remained in the data and regression formulas and r2 va lues changed o nl y slightly.

Potential Discharge

Mapped saline site polygo ns were used to cookie-wt topograph ic attribute datasets • k = (Z - Pw) / S to examin e signatures associated w ith Wh ere: P w = Actual SWL elevation (in areas of known groundwater di scharge. bores) This was based on the assumption that T h e k-va lues were sorted and th eir saline sites represent areas where groundrelationship to topographi c attributes water is effectively in contact with th e exa mined. lt was found that k-valu es surface . R esult histograms show that formed defi nite groups with natural saline sites gene rally occur w ithin areas breaks that correlated best where 111i11i11111111 break of slope with minimum slope. Eight, is less th an 1.0° and profile fin ely- di vid ed m ini mum c urvatur e is >-0 . 0 5 ° slope classes were estab(dom in a ntl y co n cave 600 lished o n th e basis of these morphology) . .:::. k-value breaks. The k-values C The predic ted HHS grid 500 Q w ere avera ged for eac h was the n subtracted from the ...> minimum slop e class and elevation grid using map 400 used in the original fo rm of algebra to generate the D epth iii th e equati on to derive P, v Cl) to HH S grid . P ote nti a l 300 (no w r e prese nting th e discharge areas were defined pr ed i c t e d HH S a t by combini ng negative results 200 borehol es) .

0 0 0 0 0 0 0 0 from the D e pth to HH S grid 0 0 v-, 0 0 0 0 rr, rr, v "V V'l <'I N 'D E levation residuals were with the salt signature condiSWL Elc\'ation in Bores (m) tions o utlined above . T he deri ved by subtracting the predi c ted .H HS eleva tio n estimated pote ntial disc harge from observed water level Figure 2. Linear Regression for HHS Elevation (m) v's SWL area within th e s tud y ele vati o n. Maj o r spik es ca tchm ent totals - 16 km 2 .

Elevation in Bores (m ) DLWC data , 1920 to 2000, Pipe-1, (approx imately 6% of the Th is area expands 56% to 25 Spikes Removed (1974 points).

.. ..

= =

V)

V")

V") LI"')

WATER OCTOBER 2001

39

GROUNDWATER

km2 w hen the critical groundwater depth is relaxed to within 2 m of surface. A comparison of the potential discharge map with known salt sites shows reasonably good correlation in the southern part of the catchment, but less so elsewhere.

Although the potential discharge map is regarded as 'approximate', the results provide a relative basis for identi fying areas at high risk of salinisacion at regional scale.

Flownet Analysis

A Flownet was constructed fo r the 735 km 2 Buckinbah C reek Catch1nent to determine grou ndwater and salt flu x. Key input included a smoothed and aggregated HHS grid, the catchment bou ndary and recharge and transmissivity files. Input va lues for recharge (20 mm/yr; 3.3% recharge race using 604 111111./yr rainfall) and transmissivity (2 1112 /d) were selec ted using limited data from previo us work.

Flownet simu lations were conducted using five different rec harge estimates to examine the resul ting changes in groundwater fl ux. The results demonstrate that any recharge above approxim ately 5 to 6 m m/ yr will contribu te to groundwater rise because the system only has the capacity (assuming a maximum transmissivity of 2 1112 /d) to conduct 17,872 m 3 / d. The system reach es its maxim um capacity to cany water when the recharge rate is - 1% (assu ming an average an nual rainfall of about 604 111111) .

Using a groun dwater fl ux of 17,872 1113 / d and an average groundwater salini ty of 1,772.4 mg/ I (2,532 ~LS/cm) the sale fl ux for the catchment is estimated at abou t 31.7 tonnes/ day. T his equates to an annual total of 11,500 tonnes/ yr (15 .7 tonnes/km 2 per yr) . Sale inpu t to the Flownet catchment from an average rainfall of 604 mm/yr was calculated at 9 tonnes/day. T his equates to an ann ual total of 3,278 tonnes/yr (4.46 tonnes/km 2 per year) .

Conclusions T he H ARSD method has proved a useful to ol for salinity assessment at regional scale in the 1075 km2 Little River study catc hment. H yd rogeom o rph ic classificatio n has ap plied automa ted techniques based on the DEM and its derived topographic attributes to disaggregate the landscape into H GU's in an objective, repeatable and efficient m anner.

Visual examination of identified landscape units reveal their close spatial relationship to both geo logy and topography.

A HHS was generated from sparse bo rehole data by developing linear regressio n relationships between surface elevation and observed groundwater 40

WATER OCTOBER 2001

AND

SALINISATION

levels taken o ver an 80 year period from 1920 to 2000. R egression formulas were deri ved for eight finely-divided slope categories and applied to the elevation grid to construct the regional scale grou ndwater surface. Th e predicted HHS compared satisfactoril y against observed groundwater levels (r2 = 0.99) . R esiduals were small for areas of low slope , b ut sh owe d in c rea sing variability with increasing slope . Potential discharge sites were identified using map algebra on surface eleva t ion, th e HH S and topographic attribute conditions derived for saline sites. These sites compared favourably with mapped salt sites in the southern part of the catchment, but less so elsewhere.

A flown et co n structed for th e Bucki nbah Creek subcatchment using FAS has produced estimates fo r groundwater and salt flu x . Simulations using different recharge estimates show that any recharge above approximately 5 to 6 m m /yr will contribute to groundwater rise beca use the system only has the capacity (assuming a maximum transm issivity of2 1112 / d) co conduct 17,872 1113 / d.

Using th is grou ndwater flux and an average groundwater sa linity of 1,772.4 mg/ l (2,532 ~LSI cm) the salt flu x for the catchm en t was estimated at about 31.7 ton nes/ day.

Follow-up work planned for Phase- II of this project will focus on hydroecological and hydrological stu dies and rem ote sensing applications to investigate salinity in a high-risk subcatchment of Buckinbah C reek iden tified during the current study.

The Authors Simon Davies is a H ydrogeologist and G IS Manager w ith Golder Associates, Milton, QLD 4064 e-mail sdavies@ golder.com.au Telephone 07 3217 6444.

Daniel Pollock and Dr Ramsis Salama are with CS IRO, Land and W ater, Wembley, WA. Dr Bill Milne-Holme is a Senior Lecturer in H ydrogeology at the National Centre for Ground water M anagement, University of Technology, Sydney.

References AGSO , (1999) . Expla11atory 11otes, Dubbo ¡[ :250,000 geological sheet. 2nd Ed, SI/55-4.

Compilers - N.S. Meakin and E.J. Morgan.

Edited by R.A. Facer and J.R. Stewart.

Department of Mineral R esources, NSW; Geological Survey of NSW and; Australian Geological Survey Organisation.

Callan , T. (1995). Th e hydrogeology of a dryla11d sali11ity ~ffected catc/1111e11t a11d reco111111e11datio11s for site spec[fic re111ediatio11 - S1111/op, Welli11gto11 .

M .Sc. Project R e port, National Centre for

Groundwater management, University of Technology, Sydney (Unpublished).

Davies, S. W . (200 I). Hydrogeomorphic Analysisfor Sali11ity Mmiage111e11t i11 the Little River Catd1111e11t, Upper /\1/acq11aric Valley, NSW. M.Sc. Project R eport, National Centre for Groundwater M anagement, University of Technology, Sydney (Unpublished).

H umph ries, E.j. (2000). Sali11it y risk assess111wt ,if tlie Ceutral W est catc/1111e11t (Macq uarie, Castfrre,;~1, a11d Bogm, catc/1111e11ts). A joint initiative of the Central West Catchment Management Conmtittee and the Department of Land and Water Conservation.

Kazemi, G . A. (I 999). G ro1111d111ater factors i11 tlie 111a11a,~e111e111 of dryla11d sali11ity i11 Ifie Upper Macquarie Valley, NS W , A11stralia. Pli.D. Project R ep o rt, National Centre for Groundwater management, University of Technology, Sydney (Unpublished).

M Dl3MC, I 999. (Murray-Da rling Basi n Ministerial Council) . Tlie Sali11ity Audit: A 100 year perspective, 1999 . MDBC, Canberra.

Nicholson, A. T. (1996). Locatio11 ofsa/i11e sites i11 relatio11 to geology a,l(/ lm1r/fom1s. /11: Semple, W.S (cd), Koen , T .B ., Williams, B .G., Murphy, B.W. and Nicho lson, A.T. ( 1996) .

Sali11e seepage scalds i11 the Ce11tral West ef NSW. Report Oil Stac~e-2 a rategorisariou ,ifsali11e sites project. T echnical Report No. 29, pp 60-67, D epartment of Land and Water Conse1vation .

PMSEIC (Ver. 2), 7 Jan, 1999. (Prime Minister's Science, En g in eerin g, and In no vation Council). Dryla11d sali11ity a11d its impacts 011 ntral i11dustries a11d the la11dscape. Commonwealth of Au stralia. 2nd M eetin g, Friday, 4 D ecember 1998, 9am to 12.30pm. Cabinet R oom , Parliament H ouse, Canberra .

Salama, R .B., H atton, T. and Dawes, W. ( I 996).

H AR.SD: Procedures a11d approaches to la11dscape c/assificatio11, gro1111d11mter-level 111appi11g, m1djlo111 11et 1110delli11g. T echnical M emorandum 96: 27, December, 1996. Division of Water [l..esources, c sm.o.

Salama, R .B., Ye, L. and Broun, J. (1996a).

Comparati11e study ,if methods of prepari11g hydraulic head s11rfaces a11d the i11troductio11 ,if automated hydrogeological- C IS tech11iques. J. H ydro!. (185) Issue 1-4, 1996. pp 115-136.

Salama, R..B., H atton , T .J. , Elder, G.M . and Ye, L. (1997). Hydrogeological characterisatio11 ,if catch1ue11ts 11si11g Hydrogeo11101phic Aualysis ef Regio11al Spatial Data (HARSD): Characrel'isatio11 efAxe Creek Catd1111e11t, Vicro,ia , Australia. p 153-166.

I,, M . T anaguchi (ed.) 'Subsurface hydrological respo11se to laud co11er a11d /a11d use cltm1ge'.

Kluwer Academic Pub!., Norwood, MA. Salama, R .B., Bartle, G.A., Ye, L. , W illiamson, D .R.. , Watson, G.D. and K napton, A. (1997a). Hydrogeomorphology a11d Hydrogeology eftl,e Upper Kem Ri11er Carc/u11e11t a11d its co111rols 011 salt distrib11tio11 a11d patterns of gro1111d111ater disc/wrge. CSIRO, Land and Water, Tech nical R eport No. 27/ 97, October 1997.

Salama, R.B. , Otto, Claus J. and Fitzpatrick, R .W. (1999). Contrib11tio11s efgro1111dwater co11ditio11s to soil a11d water sali11isatio11. Hydrogeology Journal (1999) 7 : 46-64.

Salama, R ., Hatton, T. and Dawes, W. (J 999a) .

Predicli11g laud 11se impacts 011 regio11al scaleJ1ro1111d111ater recharge a11d discharge. J. Environ .

Quality. Vol. 28: No. 2, 446-460 (Mar-Apr 1999) .

~r

~

GROUNDWATER AND SALINISATION

AQUIFER STORAGE AND RECOVERY: REMOVAL OF CONTAMINANTS FROM STORED WATERS S Toze, P Dillon, P Pavelic, B Nicholson, M Gibert Abstract Aquifer storage and recove1y 1s recogn ized in the USA as having a sign ificant role fo r inter-season storage of drinking wate r , and in Europe and Australia also fo r its potential fo r wate r trea tm.ent. Ho weve r better knowledge of water quality c hanges during aquifer storage and recovery, along with better understan ding of susta in abl e treatment processes in aquifers is necessary to enable water utilities to take adva ntage of this tec hniqu e.

The usefulness of aqu ifer storage and recovery to improve th e qual ity o f inj ected water is being investigated at several sites as pa rt o f an AWW ARF project. Specific interest is on the a t t enua t io n rates of mi c ro bi al pathogens and organic co mpo unds (both natural and synthetic) in saturated grou ndwater at artificial recharge sites. Microbial pathogens of particular interest are e nteric viruses and protozoa, while the o rgani c che mi ca ls being investigated include seve ral disi nfection-by-p rod u cts and e ndocrine disruptors. The aim is to encapsulate the data obtained from thi s investigation into models for th e prediction of changes in water quality, and which can be used by water uti lities and regulators to eva lu ate pretreatment requ irements fo r aqu ifer storage and recovery. Th is will also provide va lidated information for the protection o f the health of consumers and the environment.

Introduction In some instances storage of wa ter by injection into aquife rs may be significantly cheaper than surface storage (Pyne, 1995) with added benefits such as eli mination of evaporative losses, reduced chance of conta m in ation during storage, and the potential for enhancement of the q uality of ra w water during storage. Aquifer Storage and R.ecovery (AS R ) involves the injection of water in to an aq uifer and recovery usi ng a single bore (Pyne, 1995). H owever for conven ience, in this paper, th e term is used to also include This paper was presented at the I0th Biennial Symposium 011 the Artificial l"techarge of Groundwater, T uscon, Arizona, June, 2001

Septe mber 2002 (http: / /www. g r ou n dwater . com . a u / co n f/ ISAR4.htm). The results are expected to be of value to the water u tilities and regulators in re-eva lu ating pre-treatment require ments fo r water inj ected into aquifers as well as improving the acc uracy of information for the protection of the health of consumers and the environment.

Geochemical Changes Associated With ASR

cases where there are separate inj ection and recovery wells. T he quality of injected water has been shown to change during storage, often resulting in a signi ficant im p roveme n t. Fo r examp le, attenuation o f path ogens and organi c substan ces d urin g storage of non-potable sou r ce waters (suc h as capt ur ed stormwater and reclaimed water) can enable it to reac h a quality that meets th e requi re ments for potable supp lies.

H owever, a better knowledge of water quality changes during aquifer storage and recovery, along with better understanding of sustainable treatment processes in aquifers is necessary to enabl e water utili ties to take advantage of these processes.

An American Water Works Association Research Foundation (AWWA RF ) project (No 2618) commenced in Feb ruary 2000 and involves a total of nine ASR sites, three in Austral ia and six international. T he project is managed through CS IRO Land and Water in Australia. The proj ect aims to evaluate sustainable attenuati on rates for selected pathogens and organics (natu ra l and synthetic), in groundwater at ASR sites, based on field and laboratory data. l t is intended to encapsulate this knowledge into simple models to predict changes in water quality and to test and report on the predictive performance of these models at fie ld test sites. Partn ers of the project have five monitored field sites in USA, four in Australia and one in the Netherlands. The outcomes of the study will be comm un icated widely, including at the 4th International Symposium on Artific ial Re charge in Adelaide,

In ASR systems the introduction of aerated waters into gro undwater, particularly into an ae robic gro u ndwater, m ay induce various geochemical reactions that include mineral precipitation and dissolution , cation exc hange and redox reactions, which in most cases are mediated by micro-o rga nisms (see Figure 1 for an example of redox changes due to ASR.).

Injected water m ay contain labile orga nic matter, w hi ch acts as a redu cing agent in redox reactions.

Aerobic status influ ences the activity of indigenous groundwater microorga ni sms th at have a large role in assimilating natural and synthetic organi cs and in fl uences the survival of introdu ced pathogens. Movement of water between redox zones within an aquifer during injection and storage affects the release or adsorption and attenuation of metal or inorganic contam inants

Fate of Disinfection-By-Products (DBPs) Disinfection is often used for waters injected into aquifers, particularly in the USA. Besides reducing pathogens it assists in controlling b iological clogging around the injection well (Fox et al., 1998). C hlorine is used m.ost w idely fo r disinfection, as it is cheap and effective.

r-··;.~)~:.-:.:.

\ :

._'·_··_.._·~cc ~~o,~::_,:_:._::_.·:_:~----"<'"/··_ ··_".....J

~:;n~>IA(IV)

:.:::*'«

Figure 1. Schemat ic of redox changes due to the injection of aerobic wate r into an anaerobic aquifer WATER OCTOBER 2001

41

GROUNDWATER

H owever some of the halogenated DBPs produced during chlorination are carcinogenic in animals and are therefore possible human ca r ci no gens. Chl o ri na tion produces a range of DBPs of w hich the triha lomethanes (T HMs) and haloacetic acids (H AAs) predominate. Concern over the possible deleterio us health effects associated with exposure to DBPs in drinking water has led to the introduction of strin gent guidelines and standards for these compo unds. These standards can be difficult to meet, even in waters w ith moderate levels of natural organic m atter.

Attenuation ofDBPs is possible during ASR. During storage, concentrations of disinfection by-products (DBPs) can be reduced via a number of processes such as dilution/ dispersion, chemical and microbial degradation and adsorption (M cCarty et al., 198 1). Attenu ation by adsorption processes will depend on the organic content of the aquifer and the hydrophobicity of the DBP. In aquifers of low organic content, this will tend to be minimal. Removal of THMs by hydrolysis will not occur at a significant rate. Microbiological attenuation ofDBPs such as T HMs and H AAs has been demonstrated in practice. H owever, the biological degradation of th e differe nt DBPs are subject to the redox conditions in th e aquifer. Fo r example, HAA removal can occur relatively quickly under aerobic conditions while T HM removal requires anaerobic conditions (Singer et al., 1993; Pyne et al 1996) . The removal of chloroform only occurs under sulpha te redu cing conditions or conditions of methano genes is. Brominated THM removal also occurs under these conditions, but removal can also occur under less highly reducing conditions of denitri-

AND

SALINISATION

fication. The more highly brominated THMs are m ore readily rem oved under these conditions. T hus, du ring the attenuation process, bromofo rm tends to disappear most rapidly.

Some examples of field studi es on the fate of DBPs are summarised in Table 1.

At fo ur of the five cases listed in Table 1, a decline in the level ofDBPs occurred through the storage of treated water in an aquifer. The removal of DBPs in these ASR schem es was attributed to both abiotic and biolo gical pro cesses. It was noted in one of the studies that the more highly brominated compounds of both THMs and HAAs were degraded fastest.

In one of the five studies, the THM concentrations were observed to in crease during short storage periods. This was considered to be due to oxidation of organ ic carbon resident in the aquifer in the aerobic zone in th e vicinity of the injection well.

Persistence of Endocrine Disruptors Endocrine disruptors are exogenous substances that inteLfere with the structure and fun ction (s) of the endocrine system ca using detrimental effects to organisms and their offspring. Their effects are largely th ough interacti on with h o r mone receptors of th e affected orga nisms .

Effects attributed to endocrine disruptors include the development of testicular and prostate cancer, reduced sperm production in humans, and demasculation, fe minisation, alteration of immune functions and decreased fertility in birds, fish, reptiles and m ammals. It is now well established that many chemi cals, bo th natural and manmade, with various types of endocrine activity, are prese nt in wastewater and

rece1v111g aquati c en vironm ents and therefore can potentially be present in the source water for artificial recharge. T hese can include oestrogenic and anti-androgen ic compounds used in industrial and ag ricultural activities; as we ll as compo unds used in the domestic environ ment such as synthetic horm ones used in contraceptive pills.

The behav iou r and fa t e of four endocrine disruptor indicator compounds in aquatic enviro111nents have been examined as part of the AWW ARF project. Two o f these comp ou nd s, Bisphenol A (BPA); and 4-nonylphenol (NP) are used as industrial surfactants and plastic additives. Two ste roid hormones were also selected (17b-estradiol and l 7aethyn yl estradiol) . T h e information gathered so far has shown that attenuation of endocrine disruptors is possible through a series of abiotic and biological processes.

Abiot ic processes kn own to be involved in endocrin e disruptor removal include adsorption co solids and sediments, volatilisation, hydrolysis and pho tolysis (although pho tolysis is not relevant fo r ASR). BPA has a high soil sorption co nstant (Koc) and that for N P is very high, and both have been shown to adsorb co suspend solids and sediments in streams (Blac kbu rn et al. 1999). R eported adsorp ti on of the estra di o l steroid hormones suggests that these w ill be strongly sorbed to the surfaces on aquifer materials, particularly u nder an aerobic conditions (W ill iams et al, 1999) .

Biodegradation rates for the endocrine disruptors are given in Table 2.

While, the relative risk from endocrine disruptors is still being debated, and their environmental behaviour and fate is still poorly unders tood, they cannot be

Table 1. The fate of DBPs in f ive ASR schemes.

Study Site

Compounds

Aquifer

Outcome

Reference( s)

El Paso, Texas

THMs

Sand and gravel layers

THM attenuation with brominated THM s being more effectively removed

Buszka et al. , 1 994

Palo Alto Baylands, Ca lifornia

chloroform, bromoform

silty sands and gravels

Indication of THM degradation under anoxic conditions/ retardation factor of 3 determined for chloroform.

Retardation related to hydrophobicity and organic content of aquifer material

Roberts, (1985); Roberts et al., 1982

Las Vegas, Nevada

THMs and HAAs

lnterbedded silts , sands and gravels

Miller: no THM removal when dilution through mixing taken into account Recent: HAAs decline rapidly due to microbial oxidation.

THMs cones. (es p. ch loroform) increase initially and decline due to mixing/some evidence for degradation of bromoform (TH M and HAA findings supported by lab study)

Miller et al.

(1993); Thomas et al.

(2000); Landmeyer et al.

(2000)

Memphis , Tennessee

THMs, HAAS, and many other compounds

Clastic sediments; si lt, sand, & gravel

THMs increased during storage. H2 0 2 treatment of injectant eliminated problem. Lack of information on possible byproducts of H2 0 2 has delayed ASR.

Fred van Hofe and James Webb (pers. com.)

Charleston South Carolina

Tota l THMs

Dual porosity limestones underlain by silty muds

Declines reported due to mixing/attenuation rates as yet unknown

Mirecki et al.

(1998)

42

WATER OCTOBER 2001

GROUNDWATER

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faecal st r e p tococci ranging from 3 to 33 days with a mean of10 days and m edian of Time For Complete Biodegradation Endocrine Disruptor 4. 3 days . Viruses and Bisphenol A 7-14 days (Staples et al. 1998) coliphages had a similar 4-nonylphenol Persistent (Ahel et al. 1 994, Bennie range of removal times, et at. 1998, Giger et at. 1984 w i t h spec i es of 6-10 days (Williams et al. 1999) 17~-estradiol Poliovirus, Ec hovirus, 17 â&#x20AC;˘ -ethynyl estradiol 13-20 days (Williams et at. 1999) Coxsac ki ev iru s and Rota v i rus h avin g ignored in the context of water reclarem oval times of between 3 and 33 days mat ion . An understanding of any (in nine studies), and various coli phages sustainable attenuation of these substances between 1 and 7 days (from fo ur studies). as a result of aquifer storage wo uld enable In formation on protozoan inactivation in ASR to be considered as a poten tial groundwater is scant. A preliminary treatment stage fo r the removal of suc h study by R agusa et al (l 998) in the T2 co mp o unds from water sources. aqu ife r at Andrews Farm , Adelaide, (where storm water was being irtjected) Survival of Injected Pathogens fo u nd that for two species of Ciardia During Storage (intesti11alis and 11111ris) rem oval times ran ged from 7 to 23 days.

Pa veli c et al (1996), Dillon (1996) and T oze (1997) rev iewed the lite rature R emoval rate differs with species and concerning the survival and viabil ity of depe nds on a range of c he mical, physical path ogen ic mi croorgan isms in aquifers. and biological factors. T he facto r that has Numbers of organisms commonl y decline the most sign ifi cant in0u ence is temperat an exponential rate (analogous to a t u r e , w ith hig h er t em p e ra t ur es radioacti ve decay). T he time over w hic h accelerating rem ova l (Yates et al. 1985, the n u mber of via ble organism s declines J ansons et al. 1989) . Som.e other factors to 10% of the initia l number is the onesu ch as the prese nce o f indigen ous log10 re moval time, hereafter abbreviated groundwater microorganisms and water to 'removal ti me'. chemistry have also been shown to have so me influ ence on pathogen survival in Pu blished resu lts have determined gro u ndwater (Nasser and Oman 1999, that fi ve species of enteric bacteria had Yates et al. 1985) . Pa ve lic et al (l 998) removal times of 3 to 33 days. Six developed a diffusio n chamber m ethod to indepe nde nt laboratory and fi eld studi es quantify pathogen inactivatio n i11 -sit11 in of E .coli surviva l in groundwater fou nd groundwater. They found t hat t he remova l tin1es of 3 to 20 days, with a presence of aqu ife r m ed ium prolo nged mean of 5 days (Pa velic et al, 1996). The surviva l when co mpareJ w ith pa thogens same studies sho wed removal times for Table 2. Published biodegradation times of selected endocrine disruptors.

suspended in the grou ndwater only.

R esidence time within the aquifer is the key to the fa te of any iajected pathogenic organism. W h en residence tim e of injectant in the aqu ifer exceeds several removal times of the pathogenic microorga nisms, the viable num.b ers remaining are orders of magnjcude smaller than in the inj ected water, and the risk of exposure to pathogens in recovered water is reduced commensurately. In most European cou ntries, a 50 to 60 day residence time in the aquifer is used as a basis for es tabli shi n g grou n dwater protection zones (van W aegeningh, 1985) in order to protect dri nkjng water supply wells in unconfined aquifers aga inst contamination by p ath ogenic organism s.

For the larger mi croo rganisms, such as protozoa and helminchs, with a size similar to the dimensio ns of the pores of the porous m edium, removal ca n also occu r by fi ltration during passage th rough th e aq uifer. H owever w here recovery takes pl ace fr o m th e inj ection well , no allowance can be made for passage th rough the aquifer. T he fi rst water extracted during recovery may need to be stored and recycled to avoid the potential for reticulation of water conta inin g pathogens whic h may ha ve been shielded in well biofilm str.ipped off at the start of the recovery cycle. l n a recent study on the su rvi val of selected viral, bacterial an d protozoan pathogens in grou ndwater and inj ected tertiary treated effi uent at an ASR site in Adelaide the decay rates of each of the pathogens was shown co be dependent on pathogen type, water type, and the

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43

GROUNDWATER

presence of indigenous groundwater microorganism s. The survival of all of the pathogens was found to be significantly less under non-sterile conditions than in sterile groundwater or injected wastewater.

The bacterial species tested had the shortest survival times, with survival ofless than five days under non- sterile conditions. Poliovirus was sign ifi cantly more persistent than th e ba c t eria, w ith C ryptosporidh1111 parimm oocysts being the most resistant of the pathogens tested.

The water type also had a detectable influ ence on the survival of the different pathogens. E. coli survived better in the inj ected wastewater than in the native groundwater, whil e Aero111011as /1 ydroplti/a survived better in the native groundwater than the injected wastewater. Sall/1011el/a typhimurium had a similar survival rate in both water types. Th e type of water had little influence on the survival of poliovirus.

In laboratory studi es we have also found th at the effect of indigenous g r ou n dwa ter microorga n isms on poliovirus can be influen ced by the metabolic activity of the groundwater microorganisms. An increased loss of poliovirus pa rticles was observed wh en groundwater 111.icroorganisms were stimulated through the addition of additional nutrients. In add ition , th e increased loss of po liovi rus particles was also observed in autoclaved and filter-sterilised groundw a t e r that had contained t h ese metabolically active microorganisms.

Conclusions The data obtained fro m literatu re searches and re sea r c h dur in g th e AWW ARF proj ect has already shown that aquifers have a substantial capac ity to change and improve the quality of water stored in them at ASR sites, pa rticularly with respect to pathogens, disinfection byprod ucts and some substances that are indicators of endocrin e disruptors. It is also clear that th e processes affecting th e fate of the various co ntaminants are interdep endent. Although the state of knowledge of most of the processes is only qualitative, one of the aims of th e AWWARF proj ect is to encapsulate this knowledge into simple models that will assist in the prediction of changes in water quality, and to test and report on the predictive performance of these models at fi eld-test sites.

Acknowledgements The work presented in this paper was made possible by the financial support of the AWW ARF Proj ect 2618. Support has also been provided by the Steering Committee of the .Bo livar ASR Research Proj ect. T he project partners are CS IRO ,

44

WATER OCTOBER 2001

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Primary Industries and Resources SA, United Water Intl. P ty Ltd , South Australian Water Corporation, and SA Department of Administrati ve and [nformation Services. The authors thank the following project partners who contributed informatio n used in this paper; Vivendi, M emphis Light, Gas and Water Division, Las Vegas Valley Water District, C ity o f C harleston and US Geological Survey.

The Authors Dr. Simon Toze, Dr Peter Dillon and Dr. Paul Pavelic are all members of the Centre for Groundwater Studies, CS IRO Land and Water. Simon is based in Perth , Peter and Paul are based in Adelaide. Dr. Brenton Nicholson is at the Australian Centre for W ater Quality, Adelaide. Dr. Michel Gibert works for Anj o u R echerche, V ivendi, Paris. Contact: PH (61 8) 9333 6130; FAX (61 8) 9333 62 11 ; Simon.Toze@csiro.au

References Ah el M., Giger W, Koch M , 1994. Behaviour of alkyphenol polyethoxylare surfactants in the aquatic environment - I. Occurrence and t ransformation in scw,1gc treatment, vVarer Res, 28:1 131- 1142.

Benni e D T, Sullivan C A, Lee H B, M aguire R. J, I 998 . Alkylphenol polyethoxylate metabolites in Canadian sewage treatment plant waste streams. Warer Q 11a/. Res. J. Ca11ada, 33: 231-252.

Blackburn M A, Kirby S J , Waldock M J , 1999.

Concentrati ons of alkylphenol polyethoxylates entering U K estuaries. Mar. Polltl/. Bull., 38:!09-118.

Buszka P M , Drock R D , H ooper R. P, 1994. l-l ydrogeology and Selected Water-Quali ty Aspects of the H ueco Ba lson Aquifer at the Hueco Balson R echarge Project Arca, El Paso, Texas. Water-R esources Investigations R e p ort 94-4092. Austi n , Texas: U S Geological Survey.

Dillon P J , 1996. Groundwater pollution by sanitatio n o n tropical islands: A UNESCO IHP study. Centre fo r Groundwater Studies R.eport No 66 .

Fo x P , Wang L , Johnson P C, H o uston S, Houston W N, Brown P, 1998. Chloiination for control of biological act ivity during direct recharge o f tertiary effiuent. 111/arer Sci. Teclu10/., 38 (6):55-62.

Giger W , Brunner P 1-1 , Schaffoer C, 1984. 4nonylphe nol in sewage sludge : accum ulation of toxic metabolites from nonionic surfactants.

Sci., 225 :623-625 Jansons J, Ed111onds L W, Speight 13, Bucens M R., 1989. Survi val of viruses in groundwate r.

Water Res., 23 (3):301-306.

Land111eyer J E, Bradley PM , ThomasJ M, 2000.

Biodegradation of disinfection byproducts as a potential re111oval process duri ng aqui fer storage recovery. J. A111. Warer VliOl'l:s Assoc., 36 (4):861-867.

McCarty PL, Reinhard M , Rimnann B E, 198 1.

Trace organics in groundwater. E1111iro11. Sri. Ter/1110/., 15:40.

Miller C J, Wilson LG, Amy G L, Brothers K, 1993. Fate of organochlorine compounds during aqui fer storage and recovery. Ground Water, 31: 410- 416.

Mirecki J E, Campbell B G, Conlon K J , Petkewich M D, 1998 Solute changes du,ing aq uifer storage recovery testi ng in a limestone/ elastic aqui fer. Cro1111d Water, 36: 394-403.

N asser A M, Oman S D , 1999. Quantitative assessment of the inactivation of pathogenic and indicator viruses in natural water sources.

Water Res. , 33 (7): 1748- 1752.

Pavelic P, Dillon P J, Ragusa S R , Toze S, 1996.

T he fa te and transport of micro-organisms introduced to gro un dwate r through wastewa t e r rec lamation. Centre for Groundwater Studies R e port No. 69.

Pavelic P, Ragusa S R, Flower R. L, RinckPfeiffer S M , Dillon P J , 1998. Diffusion chamber method for in situ mearnrement o f pathogen inactivation in groundwater. vliarer R es., 32 (4): 1144- 1150.

Pyne R D G (1995) . Gr01111dwater recharge a11d 11,el/s: a .~uide lo aquifer srorage aud reco11e0â&#x20AC;˘. CRC Press, Florida.

Pyne R. D G, Singer P C, Miller C T , 1996.

Aquifer Storage Rcc,wery ef Treated Dri11/:i11g Warer. D enver, Colorado : A m erican Wate r W o rks Association R esearch Foundation.

R.agusa S R. , Flower R L P, Dillon P J , Pavelic P, 1998. M easureme nt of pathogen inactivation in artificially recharged stormwater. In Proc. /AH lnrl Cro1111dwater Cor!f : Crou11dwa1er S11srai11able So/11tio11s, Melb, Feb 1998 , eds TR Weaver & C. R.. Lawrence. p545-550.

R oberts P V, l 985. Field o bservatio ns of organic contaminant behavior in the Palo Alto baylands. In: Asano, T. (Ed.) A n(firial Recharge ,!f Gro1111dwater, pp. 647-679. Stoneham, M ass: Butterworth.

Roberts P V, Schreiner), H opkins GD, 1982.

Field study of organic water quality changes during groundwater recharge in the Palo Alto Baylands. War er Res., 16: l 025- 1035 .

Singer P C, Pyne R. D G , M allika,jun A V S, Miller C T, M ojonnier C, 1993. Examin ing the impact of aquifer storage and recovery on DBPs.J. A111. Water Works Assoc., 85 ( 11):8594.

Staples CA, Dorn PB, Klecka G M , O'Block S T , H arris L R., ¡1998 . A review of the environmental fate, effects, and exposures of bisphe nol A, Clre111osplrere, 36:2 149-2173.

Thomas J M, McKay WA, C ole E, Landmeyer J E, Bradley P M , (2000) The fa te of haloacetic acids and trihalom cthancs in an aquifer storage and reco very program Las Vegas, Nevada. Cm1111d Water, 38 (4):605-614.

Toze S, 1997. M icrobial pathogens in wastewater.

CSIRO Land & Water T ech . R.eport No I / 97, 79pp .

Van Waegeningh 1-1 G, 1985. Overview o f the prote c tion o f g r o u ndwat e r quality .

IA I-I / IAHS Intl. Contrib. Hydrogco/., 6: 159166.

Williams RJ, Jiirgens M D,Johnson AC, 1999.

Initial predictions of the concentratio ns and distribution of 17b-oest radiol, oestron c and ethinyl oestradiol in 3 English ri vers, Warcr R es., 33:1663-1671.

Yates M V , Gerba C P, Kelley L M , I 985. Virus persistence in grou ndwate r. l lppl. [1wiro11.

MiO'obiol. 49:778-781 .

â&#x20AC;˘

WATER

WATER AND WASTEWATER MINIMISATION: THE FISH PROCESSING INDUSTRY IN SOUTH AUSTRALIA B Dearman, N McClure, H Fallowfield Abstract Water usage is of primary concern for small rural towns in Sou th Australia. A major study has investigated water usage and wastewater gene rati on by fish processing and related facilities in Po rt Lin co ln , a maj o r ce nt re for the aquaculture industry in South Australia.

The project was initiated as part of a major regional water reuse initiative funded by th e Fede ral Government Coast and C lean Seas (CCS) Program. The study identified opportunities for sign ifica nt reductions in both water usage and wastewater generation, resulting in major economic benefits to industty and reduced pressure on lim.ited water resources. In the period of March 1999 to March 2000, majo r fish processing facto ri es and the Figure 1. Farmed tuna local abattoir used approximately 213 ML of m ains water. In the fo llowing year improved practices identified duri ng the producers in Port Lincoln. A number of Introduction study firstly, reduced water usage to 192 m ajor fis h processors are not currently ML despite increased fish production and The Port Lincoln sashi mi tu n a connected to the local sewerage system seco ndly, identified practices to further industry, together with the processing of and discharge effiuent directly to the reduce ongo ing use by 30% to 150 ML prawns, crayfis h and canned tuna, marin e env ironme nt. In t h e 2000 per an num. T hese techniques involve contributes significantly to the econom y processing season the estimated discharge changes to m anage ment of water usage and employ ment o f South Australia into the marine environment totalJ ed during both processing and generally (T able 1). In 2000 the Port Lincoln >220,000 kg BOD and > 580,000 kg of arou nd the facto ries, and the installation canne1y employed 200 people, having an total solids in a total volume of approxof water saving devices. T he correeconomic value of approximately $50 imately 167,000 kL. A small abattoir sponding wastewater stream has also been million for South Australia. Significant simila rly di scharges to the m arin e reduced, creating a pote n ti al 30% expansion o f the cannery is underway. environment, however, the volume and reduction in wastewater volume . The The seven fish processors are the largest load is insignificant compared with the n u t r ient lo ad associated with the industrial water users and w astewater tuna processing discharge. The implewastewater stream is high due to the m entation of a new marine policy by nature of fish processing, but also due Table 1. Economic value of Bluefin sashimi tuna the South Australia Environmental to a lack of on-site treatm ent. to South Aust ra lia (EconSearch Report, 1999) Protection Authority (EPA) in March Where simple p re-treatment options 2001 removed the op t ion for such as grease arresters were used, 1998/ 99 1999/ 2000 2000 continued direct marine discharge of reductions of up to 50% in the BOD ($m) ($m) ($m) untreated effiuent in South Australia. and SS load were achieved. Waste Farming Direct 1 67 201 225 The new policy necessitated the separation at source was the focus of development of improved waste 99 107 1 20 Other Direct nutrient minimisation and is having management practices across a broad 257 308 345 Total Direct an impact by reducing the potential spectrum of industry, including 'end of pipe' treatment costs and 182 204 1 53 Value Added aquaculture and fish processing. in creasing the effectiveness of pre490 548 410 Total Production Connectio n to the local sewerage treatment devices such as grease Employment 1392 1664 1862 system was o ne option for the fis h arresters.

WAT ER OCTOBER 2001

45

WATER

processors, h oweve r , the current infrastru cture co uld not cope with all processors connecting as this would place an excessive hydraulic and nutrient load on the sewerage system and the existing waste wate r tr ea tm ent pla nt (WWT P ) r espec ti vely.

Strategies were required to improve the quality and reduce the quantity of wastewater discharged to the sewerage system. This objective could be achieved by evaluating options for pre-treatment or reuse on site, however, an overriding objective was to id entify strategies for waste minimisation. An effective waste minimisation programme not only reduces the problems of disposal of effluents but also has potential to reduce costs at Figure 2. facil ities, for examp le b y improving water u s ag e efficien cy.

A major environmen tal improvemen t program was instigated th rough an Australian Federal Government Coast and C lean Seas (CCS) grant to the City of Port Lincoln and collaborating researc h , industry, government and community agencies. Major objectives of the program included reduc ing the disc harge of untreated wastewater to the mari ne environment and im.plementing schemes for reuse of treated wastewater from domestic and industty sources via the Port Lincoln WWTP and expanded wetlands.

An integral component of the proj ect was to assist the P ort Lincoln processing facto ries to adopt effective waste minimisation strategies consisten t with the CCS project and EPA Pollution Preve ntion Fund objectives. Flinders University of

Figure 3. Clean ing guts and gills at sea

46

WATER OCTOBER 2001

tuna may engage in the on-site thawing of frozen pilchards for tuna fish feed (Figure 4). This activity uses large volumes of water.

The fish are processed either for the frozen or the fresh sash imi market. [n terms of water use and wastewater composition both methods are very similar within processors (see Fi gure 5) . The ma in difference is in processing for the frozen sashi mi market which produces additional offal and uses more potable water for glazing the fish with ice which provides protection from physical damage during transport. Tuna canning is conducted year round with production ceasing for short periods during holidays and for maintenance.

Frozen tuna

Minimisation of Water Use

South Australia (FUSA) played a major role in the research , investigation and monitoring components of the CCS programme.

An outline of tuna production and processing

A quantity and quality wastewater audit was performed over a two week period at each of the factories . P otable water usage was also monito red. The major activities investigated at the fish processing factories during the wastewater audit included;

Sashimi tuna are ma inly processed during the wi n ter period beginnin g around late March and fi n ishing no later than October. Sashimi tuna are farmed so uthern Bluefin tuna (Figures 1 and 2 ) that are mainly sold to the Japan ese market. The fish have their internal organs and gills removed, as well as being bled by makin g a small incision b ehind the pectoral fins during harvesting, at sea on th e tuna farms (Figure 3). The offal waste is either disposed to landfill or processed to fe rtiliser. Tuna processors who also farm

• thawing of frozen pilchards used for feeding tuna far med in cages off the Port Lincoln coast • processing of sashimi tuna, primarily for the export market • thawing of fro zen skipjack tuna and furth e r processing for canned tuna produ ction • rearing of crayfish • processing of prawns The volume of water used in fish processing differs between individual

Figure 4. Thawing pilc hards

WATER

p rocessors fo r t h e sa me product processed. These differences are due to the way in wh ich water is viewed by management and how processing lin es are configured w hich determines the rate at w hich the product can be processed.

The volume of water used pe r un it of product processed at each different processor is shown i n Table 2. This information is important since it permits estimates of water usage to be mad e fo llo w ing c h anges in produ ct ion sc hedules, furt hermore, it provides a bench mark targe t for less water effi cient processors to attain.

Since the inception of the CCS project, the vo lume of mains water used by fish processing factories has decreased signifi cantly. In th e period of M arch 1999 to March 2000 the fish processing factories an d an abattoi r used approximately 213 ML of wastewate r . Th e vol ume of water used in 2000 over a simila r period by the fis h processors was estimated at 193 ML. The annual period from August 2000 had a projected decrease of approximately 30% du e to redu ctions both in the vo lume of water used directly in fish processing and gene rall y within the fac tories. Th e su bsequent savings based on decreased potable water usage were approxim ately $52,870 at $0.89 per kL. T he value of these savings will be inc reased sign ifi can tl y if trade waste discharge fees are introduced , possibly with in the next 23 years. T he chan ges impl em ented are presented in the case studies below .

placed in the top of the tank holding the froze n pilchards and run continuou sly until the p ilchards we re defrosted were relocated and connected to the base of the tank. A back£l ow prevention valve on the main inlet pipe prevented backsiphoning of pilchard water into the entire factory water supply system - an Australian Quarantine and Inspection Service requ irem ent. Placing the hoses at the bottom of the bins reduced th ermal stratification and impro ved contact of the pilchards within the bin with the relatively warm mains water.

Continuously running water into the thaw bins does not all ow good en ergy exchange to occur. To maximise heat exchange between the cold pi lc hards and the relatively warm mains water, the water needs to remain within the bin for an optimum period of time. O nce th is is determined the n the water ca n be exchanged a number of times. This was achi eved by placing a solenoid va lve connected to a timer with in the main water inlet pipe to the thaw tanks. The optim um timer settin g was determin ed

by using a temperature logger, and noting w h en a temperature plateau was reached for eac h flush. This all owed water to be exchanged at specified times optimising heat exchange.

The total cost of installi ng the new pilchard thaw system was approximately $5,500. During peak thaw production in su mmer a saving of approximatel y Sl,366 per week was achi eved. It too k only 4 weeks for the system to pay for itself, fu rthermore, since pilchard thawing is conducted for approximately 6 months of th e season, the cost savings were signifi cant .

Case study 2

Cann ing tun a requires large volu mes of wate r. Mains water ente rin g th e cannery passed thro ugh two reverse osmosis (RO) systems. Th e RO reject stream was appro ximately 50% of the total volume flowi ng through the R.O syste ms. Wastewate r fro m the R O systems was previously disc harged, but it is now sto red and used as wash- down water w ith in the facto ry. M ains water

__ ·-' ~ ~ WAnR ~.,- ' ANALYSIS --- -

Cases Studies of Water Minimisation Techniques Case study 1

Th awin g of pilchards occurs w ithin so me of the fish processors. This process uses large vo lumes of water. l nitially approximately 12.3 kL of water was used to thaw I tonn e of pilchards . Some processors thaw a maximum of30 tonne per day producing a substantial volume of w astewater over the cou rse of the season . Following CCS intervention the volume of water used per tonne has decreased to between 3 .7 and 5.6 kL per ton n e, depending on mains water te1npe rature w hi ch varies over the year and influ ences thawing rate.

The savings were made by simple adaptation of the thawin g process. The prim ary m ec hanism fo r improving efficiency was by m aximi sing heat exchange between mains water which is at a temperature of approxi mately 15°C to 22°C and th e frozen pilchards at -20°C. Firstly, hoses that were originally

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47

WATER

was also used in a vacuu m pump located within the cannery.

O riginally this water was discharged after being used, but since the construction of storage tanks, this wastewater as well as the waste RO water is now stored and used as washdown water. T he savings associated with the reuse of waste RO water and vacuum pump water are significant. The total water volume saving for a typical cannery year is 8175kL, equating to a monetary saving of $7,275 for mains water.

Frozen tuna requires thawing before processing in the cannery. The thaw tanks are now more efficient in thawing tuna since heat is exchanged from the hot freezer compressor gas to the water used to thaw the tuna. T here are also large propellers located at the bottom of the tanks that circulate the water around the thawing tu na, creating an even water tern.perature throughout the entire tank. The combination of changes has halved the amount of water used and decreased tuna thaw-out time. T he same amo unt of tuna can now be thawed in half th e thaw tank volume.

Cooling of the freshly cooked tuna fi llets previously occurred in a room with the fille ts stacked on shelves and water jets spraying the fillets. This was a highly inefficient use of water, as a portion of the water did not come in contact with the hot fish fillets. A newly built cooling conveyor uses water m uch more efficiently. H ot fish fi llets travel along on a conveyer that moves slowly through the cooling tunnel. Water used to cool the fillets comes from the chiller storage tank and is sprayed onto the fillets through fine nozzles. T he nozzles act as a flow regulator, allowing a water flow-rate of 120L/ min. Since approximately 200L/min of water was being used in the old system, this equates to an annual water saving of 6,961kL; an annual monetary saving of$6, 195. An additional benefit has been in the time taken to cool the fis h, which has decreased from 1-2 hours to 2 minutes allowing an increase in the processing rate.

Mains Water

Fresh Tuna Processing

Frozen Tuna Processing Harvest Bins Ash, Seawater

:c

:c

>

¡5

Harvest Bins Flsh, Seawater

ce

and Ice

'!'

Fish Cleaning and Trimming

Fish Cleaning and Trimming

y

y

Frozen Tuna Processing

Packaged

y Exported

Freezer (Uquld N)

y Glazed

Transport Freezer

Exported

Product Flow

~

Mains Water Flow

~

Figure 5 . Water and product flow diagram typical for sashimi tuna product ion Table 2 . Volume of water used per Tonne of product processed at the major fish processing factories and the local abattoir

General Fact ory Practices General wash-down practices within all factory environments should be viewed with water minimisation in mind.

Simple wash-down techniques are very important in food production and take place at least once per day, therefore using large volumes of water over the course of the season.

Cost effective measures such as wash- down hoses fitted with flow trigger nozzles and flow regulators placed on hoses to enable low volumes of water to be used have a significant impact on the amount of water being used. In some cases, the volume of wash-down water used was halved, significantly decreasing the total volume of water used during the pro cessing season.

Processor lndlvldual Process

1

48

WATER OCTOBER 200 1

Canned Tuna - Double Shift

17.742

Canned Tuna - Single Sh ift

8. 6 1

Frozen Market Sashimi Tuna

1.013

Fresh Market Sashimi Tuna

1.974

2

Fresh Market Sashimi Tuna

1.622

3

Frozen Market Sashimi Tuna

0.448

Nutrient and suspended solid load Closely associated with water use, is wastewater discharge. Most of the major factories did not have extensive treatment systems in place, however, changes were being implemented before the CCS project. Some of these changes to wastewater treatment were simple, cost effec tive and significantly reduced the wastewater nutrient load. T able 3 shows the nutrient loads fo r each of the processors. The nutrient loads discharged from each processor at the sampling point did not undergo any extensive pre-treatment. Two processors discharged to the wastewater treatment plant, however, this account fo r only 6% SS, 11% BOD, 15% TKN , 2 1% P and 13% of the volume. The remaining discharge contributes significantly to nutrient availability in the marine environment.

Volume water per unit of product (kl/ tonne)

4

Fresh Market Sashimi Tuna

1.097

Pi lchard Thawing

0.828

Fresh Prawns

27.41

Frozen Prawns

40 .39

Crayfish (seawater)

12.09

Fresh Market Sashimi Tuna

1.85

Pi lchard Thawing: original method

15. 22

Pi lchard Thawing: new CCS method

7.00

5

Animals

0 .260/unit

6

Frozen Market Sashimi Tuna

0 .421

Frozen Market Sashimi Tuna

0.398

Fresh Market Sashimi Tuna

0.929

7

Pi lchard Thawing: original method

12.26

Pi lchard Thawing: new CCS method

4.35

*Note that the eight h processor was not included as there was only a minimal volume of freshwater used in processing, as the product processed used primarily seawater.

WATER

Data from fish processing facto ries Table 3 . Port Lincoln individual processor and combined effluent loads (Tonnes) using pre-treatment devices to reduce the and the t otal industry effluent volume discharged seasonally (ML/ year) nutrient strength o f wastewater indicates Annual Total 7 2 4 5 6 8 T/yr 1 3 that the total industry suspended solids (Tonnes) (SS) load could be decreased by up to 20% if pre treatment w as adopt ed by all 9.9 8.4 126.9 138.7 854.6 TS 414.2 5.7 101.1 49.7 processors. This is based o n current values 123.6 ss 104.9 2.1 4 .1 2.7 1.9 0.3 5.4 2.2 using simple coarse screening, devices such vss 92.9 1.8 3.3 2.3 2.0 0.258 8.2 0.464 111.2 as grease arresters and source separation.

BOD 186.9 3.

2 17.8 9.1 3.3 0.795 26.9 0.137 248.1 Grease arresters receiving sashimi tuna COD 40 2.9 2.1 33.0 16.4 13.4 1.9 98.5 3.1 571.1 process wastewater removed a significant 23.9 0.334 0.690 0.452 1 .3 0.083 1.8 0 .032 28.6 O&G portion of the nutrient load (T able 4). The rem o ved so lids are disposed to landfill.

18.2 0. 266 2.7 1.5 0.983 0.127 0.414 0.033 24.2 TKN Loads are impo rtant to determ in e since 0.003 11.6 10.6 0.005 0.1 31 0.202 0.604 0.002 0.068 NH4-N the relative wastewater discharge into the 0.004 0 .97 P04-P 0.526 0.004 0.097 0 .131 0.011 0.002 0 .197 grease arrester changed fro m day to day 41.6 8.4 6.0 98.1 119.5 553.4 TDS 199.9 2.9 77.0 an d to o btain an acc urate load figu re the 3.7 0.8 21.5 3.7 1 9 2 .6 Effluent 106.6 2.0 33.8 20.5 average eilluent volume for each p eriod (ML/ yr) was determined. Suspended solids could TS - Total Solids, SS - Suspended Solids , VSS - Volatile Suspended Solids, BOD be reduced further using more extensive Biological Oxygen Demand, COD - Chem ical Oxygen Demand, O&G - Oil and Grease, TKN pre- t rea tm e nt . Fl occ ul a ti on t r ia ls Total Kjeldahl Nitrogen, NH 4 -N - Ammonia, P0 4-P - Phosphorus, TDS - Total Dissolved c ondu c te d b y Fli nd e rs Uni v ersity, Solids however, ind icated that treatment by coagulation and flo cculation m igh t have traps present in the drains have been W ater m inimisation tec hniq ues were on ly marginal effects o n sol ids and shown to be extrem ely cos t effective. redesigned so that they do no t block up o rgani c m at ter co n cen tration fro m Additional benefi ts that have arisen from during processing. C ommercial opportupi lch ard thaw and sashimi tuna processing the investigation o f water mi nimisation nities fo r utilising the recovered blood and waste water. Th e d ifficulty in coagulati ng techniques ha ve been the po tential to waste soli ds e.g. for fertiliser, are currently and flocculatin g the suspended solids may increase the processing rate and reduce the being explored and a local company usin g precl ude the use o f techniqu es such as vo lu me of wastewater produced. fish process ing waste as a feedstock for dissolved air flotation / fi ltration. prod ucing an imal feed for the whi te m eat Sin1ple cost effective changes to process Waste separati on at source can sig ni f(poultry and p ig) markets has b een m ethodo logy and equ ipmen t can greatly ican tly decrease the 'end of pipe' costs, but redu ce wastewater n utrien t load, as well successfully established and is curren tly also increase the effecti veness o f treatment undergoing significant expansio n. as increasing the effi ciency of secondary devices such as grease arres ters and OA F treatment devices su ch as grease arresters.

Units. T here is an opportuni ty to separate Conclusion Po tential 'end o f p ipe' costs are therefo re h igh b lood content wastewater fro m low In creased awareness of environmental decreased w hich are impo rtant with th e blo od con tent wastewa ter durin g sashimi issues by th e processors has increased their possible introduction of fees for trade tuna processing, as the high blood content responsibility to public health and the waste d ischarge . wastewater can be restri cted from entering sus tai n abil it y o f t h e s u r round i n g the m ain d ra inage system with in the References environ ment. Th e CCS project has set in facto ries. At o ne processor the processin g EconSearch (1999) The E co110111ic lmpact of mo tion an ongo ing commitment from the tables and silt traps have been redesigned Aq11awlt11re iJ1 the Eyre Pe11i11s11/a R egio11 a11d processors in regard to waste min imisation to preve nt la rge solids >3 111111 fro m 5011th A 11stralia. R epo rt to the Aquaculture and enviro nmen tal sustainability of their enterin g the wastewater stream.. T he Gro up Primary Industries and Resources p rocessing tables are designed in su ch a industry.

South Australia. way that all th e wastewater Table 4. Daily mass difference between effluent inflow and ru ns to th e middle of th e The Authors outflow of the grease arrester during sashimi tuna processing tables, into a drai nage groove Ben Dearman 1s a and th en dow n into the catch Outflow (kg) Difference (kg) % Removal Inflow (kg) R esearch Assistant employed at bins located undern eath the th e D e p a rtm e n t of 23 5 .44 24 19 TS tabl es. T he catch bins at th e E nvironmental Health and th e 4 .87 52 ss 9 5 start of th e processing lin e School of Bio logica l Sciences, vss 9 5 4.33 48 receive all th is eilluent w hich Dr Nick McClure is a Senio r 1s p rim a ril y b l o od .

BOD 12 11.24 49 23 Lec ture r at th e Sc ho ol of Approx imately 40L is ca ught 8 .28 27 COD 30 22 Bi o lo g i cal Scie n ces, a nd from 7 tonne o f sashimi w na 40 1 .14 O&G 3 2 Associate Professor pro cessed over 3.Shrs. T h e 24 TKN 1 1 0 .33 Howard Fallowfield is the catch baskets p reve nt a large NH4 -N 0 0 NA NA Head of the D epartment of p o r tion of so lid mate rial P0 4 -P 0 0 0 .0034 18 E nviro nmental H ea lth , all at entering th e waste stream , but there are also silt traps in th e Flinders U niversity o f South TS - Tot al Solids, SS - Suspended Solids, VSS - Volatile Suspended main drain to prevent any Au strali a, Ad elaid e . E m ail Solids, BOD - Biological Oxygen Demand, COD - Chemical Oxygen Demand, O&G - Oil and Grease, TKN - Total Kjeldahl Nitrogen , rema ining solids moving into H o wa rd .fallowfield@ flind ers.

NH 4 -N - Ammonia, P0 4 -P - Phos phorus. the grease arrester. T he silt edu.a u WATER OCTOBER 2001

49

ENVIRONMENT

ml

DESIGNING A MONITORING PROGRAM FOR ENVIRONMENTAL REGULATION: PART I - THE OPERATING CHARACTERISTIC CURVE W Paul and NT Diamond Abstract While we'd like to think that decisions regarding compliance w ith a standard are black and white, they can in fact be incon-ect owing to the inevitable presence of sampling error. The risks (i. e., probabilities) associated with decision errors can be as high as 50%, which would surprise most people given the potential consequences of such errors. In this paper, the firs t of a two-part series, the purpose is to show how a statistical tool known as the operating characteristic curve can be used to quantify the risks of decision errors and , therefore, provide a sound basis for

d esignin g a monito ring program, treatment plant effluent quality, or environmental regulation. Part II, to be published in a succeeding issue, will describe a case study from Melbourne Water's Western Treatment Plant.

Introduct ion R egulators set environmental standards for physica l-chemical stresso rs and toxicants to protect environmental and public health, and this is done on the basis of ava ilable data from toxicity tests, biological assessmen ts, and epidem iological studies. Such studies aim to quantify the relationship between the dose

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(or co ncentration) of a pollutant and the risk of adverse health effects, and they are a precursor to a risk/benefit or cost/ benefit analysis that aims to estimate the maximum. risk that is acceptable to society. Risk, in the sense of environm ental risk, is a combination of the probability and consequence of a hazard .

Statistical risk is equivalent to probability, so decision error risk is the same as decision error probability.

This is a very brief description of the process used to set standards for pollutants in the environm ent. W ith the exceptio n o f the method adopted by the draft Australian and N ew Zealand Guidelines for Fresh and Marine W ater Quality (ANZE CC and ARMCANZ, 1999), the process usually fa lls short of acknowledging that compliance decisions can be in error, owing to the inevitable presence of sampling error, and explaining that the risks associated w ith decision errors can be controlled .

By sampl ing error, we don't m ean a mistake by the sampler or laboratory: we mean the random sam pling error that affects the estimated average (or percentile, or maximum) w henever a few samples are taken from a waterbody in order to estimate the true average. The sam pling error is the difference between the true value (of the mean, median, or percentile) and the valu e estimated from the sample .

Owing to sampling error, a decision m ade regarding wheth er an effiuent complies w ith a specified standard could be incorrect. In fact, there are two kinds of decision error that can be made which, in statistics, are called the type I and type II errors. A type I error is made when a com pliant effiuent is deemed to be in breach of the standard; a typ e II error is made when a noncompliant effiuent is judged to be compliant. Possible consequences of a type I error are that a discharger will be fined and perhaps ordered to upgrade the plan t, even though the effiuent is compliant; the consequence of a type II error is that a noncompliant effiuent will go undetected

ENVIRONMENT

and pose an unacceptable risk to decision error risks in statistical Comp6ant Noncompllant hyp o thesis tests. en vironme ntal o r pu bli c h ealth.

There are risks associated w ith each 0.10 Hypothesis testing and typ e of error and these are collecdecision errors tively referred to as decisio n e rror 008 risks, o r just error risks.

A statisti cal hypothesis test is a process by w hich a decision is made D ec ision e rror risks can be fo.os controlled. Acceptable e rror risks between two opposing hypotheses, can b e ac hieved in o ne or a combithe n u ll a nd th e a l t e rn a t e 0.04 hypo theses, taking into account natio n of three ways; although it should be n oted th at the in terpresampling variation and probability 0 .02 tation o f the regulator's standard will distributions. N eyman and Pearson have a significant effect o n the (1928) d eveloped th e logic of 0 .00 +-..c:::;c..,...--,.--,--magn itu des o f these risks: hypo thesis testing early in the last 80 85 90 95 100 105 110 115 120 century, and it's perhaps a little • incre as i n g th e sa mpl ing >< surprising chat it hasn ' t ga in ed frequ ency; Figure 1. Sampling distribution for X with population w ider appli cation in th e co ntex t of • upgrading the treatme nt plant; mean 95 mg/L, standard deviation 30 mg/ L, and compliance assessme nt today. and /or sample size of 52. For a critical value of 100 mg/L, In the context of compliance • chan ging th e decision n,/e u pon the probability of compliance is 88.5%, and the type ent, conside r the con cenassessm whi ch complian ce is based.

I error risk (th e probability of wrongly judging the trations of a variabl e X in an Decision rule is a statistical term , effluent to be in breach of the standard) is 11.5%. effl uent, which are independent and and b y changing the decision rule, norm all y di st ribut e d w i th a we don 't m ean relaxing the obj ecW e estimate the parameter o f interest with population standard deviatio n of 30 tives of th e regulator's limit. a sample statistic: the sample mean , median, mg/ L. T he regulator has set a licence limit In this two-part seri es we will sho w o r variance . It's important to understand o f 95 mg/L for the annual population how statistics, and th e op erating characthat population parameters are co nstants mean (i. e., th e regulatio n is expressed in te ristic curve in particular, can be used to for a given po pulation ; sample statistics, te rms of a parame ter valu e) . T he null quantify th e risk of committing eac h type on th e oth er hand , are random variabl es hypoth esis (H 0) and alternate hypothesis o f decision error and , therefo re, provide w hose valu es w ill vary from sa mple co (1-JA) woul d be w ritten in terms of the a sound basis fo r choosing a sampling sample according to a ce rtain probability parameter 11a/11e: frequency, a design effl uent q uality to be distribu tio n. T he salllpli11g error is th e H 0 : flx ~ 95mg/L (e fflu ent is compliant) ac hi eved by the trea tment plant, and a diffe re n ce b e tw ee n the pop ul a tion H A : µx > 95mg/L (effl uent is no ncom decisio n rul e to be used for assessin g paramete r and the sample statistic obtained pliant) co mplian ce. In Part I of th e article we fo r a particu lar sampl e.

The two opposing hypoth eses are describe th e basic statistical theory underA probability distribu tio n of a sa mple constructed so that eac h hypoth esis is th e lying the operating characteristic curve and statistic (or sampling errors) is called a nega tion of the o th e r; that way, if one is sho w how th e ope ratin g c harac teristic salllpli11g distribut/011. If we can assume a true the other must be false. If th e sample curve can be used to manage decision partic ular form fo r the sam pling distri data are unli kely under the null model, erro r risks. in Part II w e discuss a case b ution (e.g., a normal distribution) then we reject H 0 ; if the sam ple data are study from M elbo urne Water's W estern we have a basis for estimating the co nsiste nt with the nu ll model, we fai l to Tr e atm e nt Pl a n t , i n vo lv i n g rej ect H 0 . T o decide between th ese compl iance with the amm o niahypotheses we m ust first choose an nitro gen standard given in their Compiant Non compliant effect siz e (8) and a decisio11 mle.

E PA Lice nce.

C hoosing the effect size amounts 010 Sampling co asking wh at c han ge in th e indica tor co nce ntration fro m th e All sampling requires a subdi0.08 standard constitutes an unacceptable visio n of the material to be sampled chan ge in the risk to the be n eficial into uni ts, called sa111pling 1111its. The io.os uses of the receiving water? If you aggregate of all sampling units is happe ned to have a dose- risk curve calle d th e populatio11, and the 0 .04 (or concentration- risk curve) handy, selec tion of sampling units taken fo r the effect size would depend on measurem enc is called the sample.

0.02 how quic kly th e enviro nme ntal or W e usuall y resort to taking a publi c health risk in creases in th e sa mple from a p opulation , ra th er 0 .00 +-- - , - --,-..-=1" vicinity of the standard; if it changes 80 85 90 95 100 105 110 115 120 t h a n m eas u ring th e e n tir e qu ickly then the effec t size shoul d X populatio n , either co redu ce costs be relatively small. In this example or because destru c ti ve testing is Figure 2. Sampling distribution for a noncompliant let's imagin e th e effec t size was used co m easure the characteristic effluent with populat ion mean 105 mg/ L, standard chose n to be lO mg/L, i.e., a o f interest. deviation 30 mg/ L, and sample size of 52. For a concentration o f 95 + 10 = 105 critical value of 100 mg/L, the probability of Numerical characte risti cs o f the mg/L constitutes an ecologically (or detecting the noncompliance is 88 .5%, while the po pulati on, such as th e population biologicall y) signifi cant de partu re type II error risk (the probability of not detecting the m ea n , m edian , o r varian ce, are from the standard. This is equivalent noncompliance) is 1 1 .5%. refe rred co as pop11/atio11 parameters . to p uttin g a valu e o n the alternate

!

!

WATER OCTOBER 2001

51

ENVIRONMENT

Table 1: The four possible outcomes whenever a decision is made regarding compliance with a standard.

Truth (unknowable) Test Result

Effluent complies

Effluent In breach

Effluent complies

Correct decision.

Probability of reaching correct decision = 1- ex

Wrong decision.

Type II error.

Error risk = ~-

bili ty of compliance of 88 .5%, with this particular decision rule . This probability is determined by calculating the z-score and then referring to a table of the standard normal distribution for the corresponding probability: Z=

100 - 95 4. 16

= 1.20

Confidence level

Effluent in breach

Wrong decision.

Type I error.

Error risk = ex.

Correct decision.

Probability of reaching correct decision = 1 - ~-

P(X 5, 100)

Significance level.

Power of the test.

T here is also a maximum chance of that the effl uent will be deem ed to be in breach of the standard. So, there is a maximum chance of 11.5% that the effluent w ill be wrongly j udged noncompliant.

Now, imagine the population mean has d the effluent shifted to 105 mg/L an is actually noncomplia nt; th at is, the alterna te hypothesis is true . In Figure 2 it is shown that the probability of detecting the noncompliant effl uent is 88.5%; the probability of wrongly judging the eilluent to be com pliant is 11.5%.

T here are fo ur possible o utco m es w henever a decision is made regarding comp liance, and they are described in T able 1. The fo ur outcomes are given as a matrix, at the bottom-righ t of Table 1, w here th e colu m ns represent the tru th regarding the compliance status of the e fflu e nt (whic h , i n practi ce, is unknowable), and th e rows represent the decision made regarding compliance o n the basis of sample results. In statistical language, a type I error is made when a compliant effluent is deem ed to be in breach of th e standard, and the risk of a type I erro r is called the significance level (a); a type II error is made w hen an effl uent in breac h of th e standard is deem.ed to be in complia nce, and the risk of a type II error is given the symbol ~T he type I error risk is the disc harger's risk, w hile the type II error risk is the regulato r's risk.

In this example, the maximum type l and type II error risks are 11. 5%. These risks may seem quite high in light of the possible consequences of committing these decision errors . Defining acceptable error risks is a matter o f balanc ing the relative consequ ences of the decision errors and the cost of sampling and testing.

It is suggested in T he Australian and New Zealand Guidelines fo r Fresh and M arine Wa t e r Q u ali t y (ANZECC a n d AR.MCANZ, 1999) that the ratio of the type I and type II error risks be set equal to the inverse of the costs of the respective decision errors; this wou ld provide a basis for choosing from am.ong a range of

hypothesis: rather than stating HA as J-l., > 95, it is stated as µx = 95 + 10 = 105.

T he next step is to choose the decision rule. A decision rule is the combination of sampling frequency, or sample size (n), and critical value for the sample mean Cx'J that will be used to infer fro m the sample resu lts w h ethe r th e e ffl uent is in compliance. For the m o m.ent, we'll arbitrarily define the decision rule to be a sam pling freq uency of once per week and a critical sam ple mean of 100 mg/L. W ith a sampling frequency of once per week (i.e., n = 52 for the annual mean),

the sampling distribution will have a standard error of cr/'>/n = 30/'>152 = 4.16 mg/L. T he sampling distribution for the nu ll hypothesis (i. e., J-l., = 95 mg/L) is shown as Figu re 1.

Based on our chosen decision rule, the effluent is deemed to be compliant if a sample of size 11 = 52 has a mean less than 100 m g/L (this is the "compliant" region shown in Figure 1. It can be seen in Figure l that when the null hypothesis is tru e there is a minim um chance o f 88. 5% of correctly infe rring that the effluent is compliant, so there is a m ini m um proba-

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= P(z

5,

1. 20)

= 88. 5%

ENV I RONMENT

decision rul es, with different sa m p li n g fr e qu e n c ies a nd critica l values, a decision rule tha t gives a reasonable balance b e t wee n e r ro r ri sks a nd sampling frequ ency.

sampli ng frequen cy o f once p er day and the same critical sample 1 d, criticol volue• 100 90 mea n is shown as the solid- line ' --- 7 d, critical volue• 100 80 curve in Figure 3 . This curve is 8C .!! 70 much steeper th an the o ne ?5. based on a sampling frequency --j- -- ·!

6u 60 0 50 of on ce per week, and so th e : I The Operating ~ ' decision error risks, fo r th e :··· ii 40 Characteristic Curve: -- .. .:...·. -- -·-· --- ... ---30 discharger and the regulator, are ' .

Designing Monitoring 20 smaller fo r any given population . ' Programs, Treatment 10 m ea n. If, fo r example, th e --, --,...-'-+--~"l--- +--+100 Plants and 0 p opulation mean was 95 mg/ L, 80 85 90 95 100 105 110 115 120 then the type I error risk would Environmental Population mean be reduced fro m 11. 5% to less Regulations Figure 3. OC Curves for a decision ru les with a crit ical X of than 0 .1 %. After we ighi ng up Th e op erating characteristic 100 mg/ L and sampling intervals of 7 days and 1 day. The the potential consequences and curve, o r O C curve, is th e solid vertica l lines depict th e null and altern ate hypotheses costs o f co m mi tting a type I probab ility of dec laring an of 95 mg/L and 105 mg/L, respective ly; the effluent is error, a discharger might decide eill u en t to be in compli an ce compliant when it is equal to or less th an 95 mg/ L. the extra sampli ng effort is cost plotted as a fu nction of some effective. pop u lation parameter, such as Fo r the fi rst option, it ca n be seen fro m Thus fa r it has bee n assu med that the the m ean level of a pollutant. The shape the dashed- li ne O C curve in Figure 3 that standard was expressed in terms of a of an OC curve will change according to redu cing th e popu latio n m ean o fX from pop ulation mean (i. e., a parameter va lu e), the decision ru le used for determin ing 95 mg/L to 90 mg/ L wo uld lowe r th e rather th an a critical value fo r th e sample com pl iance. T he OC curve is, there fore, type I error risk fro m 11 .5% to less than a to o l fo r c hoosing am o ng va ri ous mean, b ut usually it's not cl ear in the 1%. For the second option , we'll o nly strategies for reducing the error risks. regulatio n wh ich value is mean t. Fo r a co n sid e r in c r ea sin g t he sa m p lin g given population, the magnitudes of the Let's re-use th e previous examp le frequ en cy, bu t equa lly we coul d change where the regulator had set an upper limit error risks are governed by the decision th e cri tica l value or both th e sampling of 95 mg/L for the annua l population rul e. If the decisio n rule is fi xed by freque ncy and critical valu e. T he O C mean of a variable X, and the efflu ent had curve fo r a decisio n ru le based on a regulation then reducing the popu lation a p op ul ation standard dev iatio n of 30 mg/L. For a sa mpli ng freq uency of once per wee k and a criti cal sam ple mea n of 100 mg/ L, th e probab ili ty o f determin ing th e eillu ent to be in co mpliance can be calculated for a ra nge of population means, ENVIRONMENTAL GROUP Water Supply & Treatment j ust as it was in the previo us section fo r popul atio n means of 95 mg/L and 105 Water Quality Management NATIONALLY mg/ L. T hese probabilities are th en plotted Management Systems & Compliance Auditing Dr Peter Nadebaum aga inst the co rrespo ndin g po pulati o n mea n as show n by th e dash ed- lin e O C (03) 9272 6666 Water Resources Development, curve in Figure 3.

Hydrology, Irrigation & Drainage NEWCASTLE W e are interested in kn ow ing the Ian Gregson Wastewater Collection, Treatment & Reuse c o n fid e n ce l e v e l ( prob a bi l it y o f (02) 4929 3255 co mpliance) or risk of a type I error when Environmental AudiVSite Investigations NSW th e e ill uent is truly compliant, and we' re Dr Ian Garrard Contamination Assessment & Remediation in terested in the power o f th e test (02) 9412 9999 (probabi li ty o f noncom pliance) or type ll Hazardous/Industrial Waste Management QLD error risk when th e eilluent is truly Solid Waste Management non co mpli ant. The first thing you m ig ht Stephen Trainor, George Khouri no tice in Figure 3 is that if the populatio n & Brad Steele Environmental Impact Statements (07) 3233 1611 m ean is 95 mg/L, th e probabili ty of Environmental Management Planning co mpliance is 88 .5% fo r a 7- d sampling VIC Emissions Testing & Air Quality Monitoring interva l, j ust as it was in Fi gure l ; the Ron Edwards & & System Development probability of a type I error is 11.5% (i.e., Dr Wayne Drew 100% mi nus th e p ercent proba bility o f Emissions Testing & Air Quality Monitoring (03) 9272 6666 co m pliance) .

WA If a type I error risk of 11 .5% seem s Warren Dodge too h igh to the discharger, then there are (08) 9220 9300 two options: 1) upgrade th e plant to ensure a population mean of less tha n 95 SA Paul Lindon mg/L (or improve process con trol to Offices throughout Australia and South East Asia (08) 8271 2322 r e d u ce t h e p o pu lati o n s t a n d a rd Website: www.egis.com.au deviatio n);or 2) fi nd a new decision rule .

100

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WATER OCTOBER 2001

53

ENVIRONMENT

mean of the efflu ent (i .e. , Bisgaard and Hunter (198 1) 100 - r - - - = - -. , . - - - , - - - - - - - - - - - - 0 concluded that standards should upgrading the plant) is the only ·········~·..,,.. j_ . ___ 1 d, end cal valu~• 95 90 ' be expressed as critical values . : ; - - - 7 d, critical valu~• 95 means of reducing the error 8 80 ------:-----~\._. --1-----~-----' ____ ., ----'-----so that discharge rs k n ow risks. It wo uld be fair to say, c : ' \ : exactly what value of the '8.70 ··· :\: however, that a regul at o r sam ple mean constitutes a 60 --:-· wo uldn't be too concerned if a o 50 -----~-----~----- -----------;·----,-----,----noncompliance . [t should be discharger wanted to increase { 40 ..... ; ----~though, th at defining added, the sampling frequency in order 30 .. · comp liance operationalJy, in to improve their risk of a type ' ' ' terms of a decision rule , can 20 · · · · - -:- · · · · -: · · · - - ~ · · .:...- ~ · · · · · f • • • • • ~ • - - • ·: - - - • • 80 I error. on ly be achieved after giving 10 T he interpretation of the du e considera t ion to th e 0 +---+---+--+---'::..,.-~----+---+ 100 regulation can make q uite a 60 65 90 95 100 105 110 115 120 desired parameter value, the Population mean differe nce to the decision error effect size, and the decision risks. If the standard used in the error risks.

Figure 4. Th e effect of interpreting the standard as a critical previous example were actually A limitation of the statistical va lue. OC Curves for decision rules with different sampling stated in terms of a critical value, methods used here is that they intervals and a critical sample mean 95 mg/L. then th e OC curve would look ass u me the data t o be like the dashed-line wrve shown ind ependent and normally possible strategies for m anaging the and in Figure 4. Now, if the population mean distributed. Environmental data, however, decision error risks have been offered. of X was 95 mg/L, the type I error risk usu alJy exhibit serial correlatio n, seasonThese stra tegies include 1) increasing the would be 50%. Upgrading the plant to a ali ty, an d heterogenous va riance . sampling frequency, 2) upgrading the population mean of 90 mg/L would Furthermore, the standard was stated in treatment plant, or 3) changing th e reduce the type I error risk to 11.5%, and the form of a mean, whereas standards are deci sion rule used for co m pliance increasing the sampling frequency to once usually expressed as percentiles and assessment . It's important, however, that per day (the solid-line curve in Figure 4) maximums , and the di stributional would further reduce it to less than 0 .1%. all stakeholders agree on the in terpretation properties of percentiles an d maximums of the regulation: whether th e standard is Conclusion for environmental data are mathematically expressed as a parameter value or as a intractable . Part II of this article, to be critical va lu e can be the difference T he nature of decision errors in published in a forthcon1ing issue, deals between upgrading a pla n t or not. compliance assessment has been described, with complex data characteristics and standards in a case study fro m M elbourne Water's Weste rn Treatme nt Plant, involvin g compliance with the ammonianitrogen standard in th eir EPA lic ence .

Controlling decision error risks will once again be the focus in Part II.

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C&SBRAND AUSTRALIAN FILTER COAL

& C&SBRAND GRANULAR& POWDERED ACTIVATED CARBONS Phone or fax for sound technical advice from experienced personnel.

JAMES CUMMING & SONS PTY LTD 319 Parramatta Road AUBURN NSW 2144 Phone: (02) 9748 2309 Fax: (02) 9648 4887 Email: jamescumming@jamescurnming.com.au Licence no: 1628 54

WATER OCTOBER 2001

QUALITY ENDORSED COMPANY AS/ ISO 9002 STANDARDS AUSTRALIA

References ANZECC and AR.MCANZ, 1999, A11stralia11 mid New Zea/a11d C11ideli11es for Fresh a11d 111ari11e Water Quality (draft), Australian and New Zealand Environme nt and Conservation Council & Agriculture and Resource Management Council of Australia and New Zealand, Canberra.

Bisgaard, S. and Hunter, W. G. 1981, 'Studies in Qua lity Im provement: Designing Environmental Regulations, Report No . 7', Ce/lier.for Quality mid Productivity l111pro11e111ent, University of Wisconsin, Madison.

N eyman, J. and Pearson, E. S. 1928, 'On the use and interpretation of certain test criteria for purposes of statistical infe rence. Part I', Bio111enika, 20A, pp. 175-240.

Authors Dr Warren Paul is Managing Director of Environmen tal Science and Statistics P/ L (ess); he is also a sessional lecturer in the Departments of Communications & I nforma tic s and Li fe Sci ences & Technology at Victoria University of T echnology. Dr Neil Diamond is a seni or l ecture r in the Department of Communications and informatics at VUT. Email: warren.pau l@bigpond.com.