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Volume 25 No 5 September/October 1998 Journal Australian Water & Wastewater Association

Editorial Board F R Bishop, Chairman B N Anderson, MR Chapman, P Draayers, W J Dulfer, P Gin, GA Holder, M Muncisov, P Nadebaum, J D Parker, M Pascoe, AJ Priestley, ] Rissman, F R oddick, EA Swinton

~ Warer is a refereed journal. This sym bol indicates that a paper has been refereed .

General Editor Margaret Metz, email: mmetz@awwa.asn.au AWWA Federal Office (see postal address below)

CONTENTS

Features Editor EA (Bob) Swinton 4 Pleasant View Cres, Wheele~ Hill Vic 3150 T el/Fax (03) 9560 4752 Email: swintonb@c031 .aone.net.au

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CK Fairley, MI Sinclair ·, Advanced Water Treatment Without Chemical Coagulants ................. 15

M Muntisov, J Stewart, K H orlock Arsenic Removal From Drinking Water ........................ ....... .. .. .... ............... 18

M Chapman Bacterial Regrowth Potential: Quantitative Measure By Acetate Carbon Equivalents ......................................... .... ... .................... .... ....................... ..... 19

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plant at Trentham. T he plant uses a unique, environmentally friendly combination of advanced processes including microfiltration, ozonation and granular activated carbon filtration to treat the drinking water of the small tow n of Trentham in Victoria. See our story on page 15 for more de tails. Photo courtesy of Gutteridge Haskins & Davey


WAYE R Abstract Australia has a unique opportunity to provide a different focus for defining what is safe drinking water. This paper summarises wh at is known about waterborne disease to date and describes the steps that are being taken by the Australian water industry through the Cooperative R esearch Centre fo r Water Quality and T reatment (CR CWQT) to unde rstand this complicated issue. Examples include the W ater Q uality Study currently unde r way in M elbourne and planned case control studies of Cryptosporidium and Giardia. The importance of molecular biology and good disease surveillance is discussed. The pape r focuses only on microbiological water quality, since other investigators in the CRCWQT are dealing with issues such as disinfection by-products.

Key Words Water quality, guidelines, standards, epidemiology, gastroenteritis, Cryptosporidium, Giardia

Introduction Defining water quality is difficult. To most people it means water that tastes and looks good and is safe to drink. The firs t two of these ideas are relatively easy to define, but the concept of safe water is extrem ely complicated (NH&MRC, 1996). There are many reasons for this, including the inability of current water quality parameters to reliably predict the presence or absen ce of diseasecausing organisms in water, the increasing numbe r of individ uals in the commu nity with compromised immune systems and the very difficult issue of deciding what is an acceptable disease risk from drinking water. In this pape r we discuss Australia's unique opportunity to provide a different direction, summarise w hat is known about waterborne disease and outline the steps being taken by the Australian wate r industry through the C RCWQT to understand this complicated issue. T he views expressed he re are those of the authors and not necessarily those of the CRCWQT. In this paper only microbiological water quality is discussed , since other investigators in the CRCWQT are dealing with issues such as disinfection by-products.

Australia's Natural Advantage Appreciating the co mplexity of defining good quality drinking water, the Australian government and water industry have wisely opted for guidelines rather than standards (NH&MRC, 1996). This is a critical difference and

IS AUSTRALIA LEADING THE WAY? C K Fairley, M I Sinclair one of th e main reasons that they are able to take a different path from that followed in the European Union and U nited States (US). In the U S in particular legally enforceable standards exist and if a water company does not meet the levels laid down in the standards it can be p enalised. This approach assumes that it is possible to set one level for each water quality param eter that can sensibly be applied to all water supply syste ms despite the widely different qualities of source water an d the treatments e mployed. It also assumes that the levels of water quality parameters accurately reflect whether or not th e individuals who drink the water will get sick. There are many examples where sub stantial numbers of p eople have become ill from consuming water that met all legally enforceable standards (Goldstein et al., 1996). Conversely, every day provides more examples where water supplies have not met these standards but have not been associated with disease. When such parameters fail to d efine safe water quality, there are two possible approaches. The first is to focu s on those less common occasions where disease has occurred despite water m eeting a pre- set level fo r water quality pa rame ters and conclude that it i s

necessary to lower the level (Goldstein et al., 1996). This would seem logical as water quali ty parameters such as indicator organisms generally indicate that faecal contamination may have occurred. T his logical approach has been in part responsible for the gene ral trend to tighten the acceptable level fo r water quali ty parameters. T his has been done in the genuine belief that it will provide a measurable decrease in disease attributable to drinking water. A recent example of this in the Australian setting is the reduction in the level of coliforms from 95% of samples with less than 10 cfu/ rnl in the 1987 NH&MRC guidelines to 95% free of any coliforms in the 1996 NH&MRC guidelines. The seco nd approach is the one that can only be unde rtaken in a country like Australia tha t operates under water quality gu idelines and no t standards. Here the Australian water industry through the CRCWQT aims to understand the relationship between water quality and human health in conside rably more detail before deciding on whether a particular level of an indicator organism should be universally adopted. Perhaps the best example of this is the Water Quality Study, which is discussed in more detail below. There are other important characteristics of the Australian water industry WATER SEPTEMBER/ OCTOBER 1998

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WATER that allow thi s approach to be taken. These include a sense of openness and tru st between governme nt, indu stry and academia, a foc u s on public health, the absence of a tradition of litigation, and the commitment of key players in the C R CWQT and the Water Services Association of Australia. It is of some significa nce, for example, that the old motto of the Melbourne M etropolitan Board ofW orks was:

'Public health is my reward.' All these factors have created the righ t en viro nm e n t for Australia to investigate a different approach to water quality.

Can Water Quality Be Better Understood? In this pap er we do n ot discuss t_h e traditional indicators of water quality such as turbidity or coliform counts, since these are di scussed in consid erable detail in the latest N H &MRC guidelin es (NH&MRC, 1996). N either do we reiterate some basic principles of w ater quality such as multiple barrie rs and the value of pro tect ing so urce wa ter. R ather, we restrict our d iscussion to how one can bette r understand microbiological water quality through epidemiology. . Epidemiology is the study of disease in p opulations and the reasons w hy disease occurs. For example, it has been used to establish that smoking cau ses lu ng cancer and that die ts high in animal fat cause heart disease. It is ofte n used together with molecular biology and other basic scientific techniques. These tech niques have been combined with epidemiology in many areas and their application to wa ter quality is discussed after we deal with waterborne gastroenteritis.

What Is Known About Waterborne Gastroenteritis? A n umbe r of w idely publicised outbreaks of waterborne gastroenteritis, t oge ther w ith so m e _ more . recent research , may give the 1m press10n that gastroen teritis may be . commonly acquired from water even 111 develop_e d countries. The reality is that ep1dermcs of gastroenteritis from wa ter are rare, and the recent research suggesting that wa ter may commo nly cause gas troenteri tis has some very significa n t me thodological flaws (Kramer e t al. , 1996¡ MacKenzie et al. , 1994; M orris e t al. , '1996; Paym ent et al. , 1997 ; Schwartz et al. , 1997 ; Payment et al. , 199 1). T his area is best considered by reviewing the epidemics and then the more co n troversial area o f e ndemi c gastroenteritis.

Epidemic Gastrointestinal Disease A waterborne epidemic of gastroenteritis occurs w he n the re is an increase in the amount of gastroenteritis above the background rate and w hen water is fo und to be the likely cause (Borgdorff et al. , 1995). A recent sum mary of wate rborne ou tbreaks from th e Uni ted States during 1993 and 1994 gives a good gen eral impression of the significance of epidemic waterborne gastroenteritis. A to tal of 30 wate rborne outb reaks of gastroenteritis occurred from drinking water: 405,366 people were affected; Giardia was resp onsible for five ou tbreaks, Cryp tosp oridium fo r fou r and Campylobacter fo r three (T able 1). In general , most epidemics are small, averaging 133 cases, and Cryp tosporidium, Giardia and Campylobacter are t he most commonly iden ti fied organisms. However, no o rganism was identified in five outbreaks (16. 7%)

Table 1 Waterborne disease outbreaks associated with drinki ng water in the United States, 1993- 1994 Orga nism/ compound

Number of outbreaks

Cryptosporidium parvum AGI Giardia lamblia Campylobacter jejuni Salmonella serotype Typh imurium Shigel/a sonnei Shigel/a f/exneri Non-01 Vibriocholerae Lead Fluoride Nitrate Copper Total

5 5 5 3 1 1 1 1 3 2 2 1 30

Number of people affected 403,271 495 385 22 3 625 230 33 11 3 43 4 43 405,366

AGI= acute gastrointestinal illness of unknown etiology Source: Surveillance for Waterborne-Disease Outbreak-United States, 1993- 1994. M MWR, Vol 45/ No SS-l

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WATER SEPTEMBER/OCTOBER 1998

during this period (AGI in Table 1). It is impo rtan t to appreciate that epidemics o f gastroenteritis represent only a tiny fraction of all gastromtestmal illness (H ellard and Fairley, 1997). In th e US, w ith a p opulation of 250 million, the re are probably about 175 million episodes of gastroenteritis every year, b ased on the average rate fo r o-astroen teritis of 0 .7 ep isodes p er ; erson per year (H ellard and Fairley, 1997). W aterborne outbreaks therefore only rep rese nt 0. 25% of all cases of gastroe nte ri tis. If the umqu e M ilwaukee outbreak is excluded , then recognised ou tbreaks of wa terbo rne gastroenteritis represent only 0 .02% of all gastroenteritis. It is important to learn from the lessons of each outbreak but also important to appreciate that outbreaks of gastroenteritis represent a very smaU proportion of cases of gastroententls (Kramer e t al. , 1996).

Endemic Gastrointestinal Illness A n um ber of studies support the concep t that drii;iking wate r may be responsible for a proportion of all cases of gastroen teritis even if no o~tbrea_k h as occurred. This proportio n 1s refe rred t o as endemic wate rbo rne gastroe nteritis. Endemic_ wa te:bo rne gastroenteritis would be 1mposs1ble to identify w ithout a specific stu dy because roughly the same numbe r of cases would occu r every day of the year. Four studies publish ed in the 1990s ha~e suppo rted the existe nce of endemic waterborne gastroenteritis (Paym en t et al. , 199 1; Paym ent et al., 1997; Schwartz et al. , 1997 ; Morris et al., 1996) . It should be noted , however, that because of the weaknesses in these studies there is considerable disagreem ent about w hether e ndemic waterborne gastroenteritis actuall/ 'e xists. It is also important to note that endemic waterbo rne gastroe nte riti s may be restricted only to certain water supply systems with particular chara~te ristics. In teres tingly, all four stu dies were carried ou t in cities with very poor raw water quality. The first study was a randomised clinical trial undertaken in C anada in the late 1980s (Paymen t et al. , 1991). T his study was followed up by a more complicated bu t basically similar study fo ur years later in the same area of Q ueb ec w hich sourced water directly from a polluted river (Payme~t e t al., 1997) . In both studies, fam1hes were randomly allocated to receive tap water or water that had been treated with a reverse osm osis filter. Family members were followed up and regularly interviewed about cases of gastroenteritis. In bo th studies the tap wate r groups had at


WATER least 15% more gastroenteritis than the group that received treated water (Payment et al., 1991; Payment et al., 1997). A more detailed description and critical analysis of these studies is available in a recent edition of the Health Stream Newsletter (Issue 7, Sept 1997, pp 1-3). Both these studies suffered from the same major methodological weakness: participants were aware of the type of water they were receiving. It is therefore possible that some or all of the difference in the rates of gastroenteritis seen in the studies may have been caused by participan ts unequally reporting their symptoms. For example, if those who received treated water under- reported their illness or alternatively those who received normal water over-reported their illness, then the study would have shown a difference in the rates of gastroenteritis when in fact one did not exist. The uncertainty about whether the observed difference was real or caused by the methodological weakness of the studies has severely limited their impact. More recently two further studies have been published that support the existence of endemic waterborne gastrointestinal disease. T he ecological study design u sed was extremely weak and subject to many different forms of bias. In both studies the number of children attending hospital emergency d epartments was compared with the turbidity of drinking water. In both studies there was a statistically significant increase in attendances in causality with rises in turbidity. In o ne study, an increase of 0.5 nephelometric units was associated with more than double the number of gastrointestinal events (Morris et al., 1996), while in the second study every interquartile rise in turbidity (0 .04 NTU) was associated with a 9.9% increase in attendances fo r gastroenteritis (Schwartz et al., 1997). The raw water in both studies was taken di rectly from a river and had poor microbiological quality. The results of both these studies m ust be interpreted with considerable caution because the underlying study design was inherently weak. At best, these studi es indicate that the concept of endemic waterborne gastroenteritis needs to be investigated with more rigorous study designs. For more details on these studies refer to recent editions of H ealth Stream Newsletter (Issue 8, D ec 1997, pp 2-5).

Endemic Waterborne Gastroenteritis-Issues To Be Resolved The first issue t hat needs to be resolved about endemic waterborne

gastroenteritis is to determine if it actually exists. This requires the use of a randomised double blind clinical trial w hich is the most rigorous study design available. The Water Quality Study which is currently being undertaken by the CRCWQT in Melbourne represents such a study. In addition to the conditions used in previous studies, this study is double blinded with neither the investigato rs nor t he participating families aware of whether their drinking wate r has been treated to remove pathogens or not. This is achieved through real and sham point- of-use filters that look identical to one another. The study, which will be completed in February 1999, began in September 1997 after rec ruiting 600 families (2,800 individuals) who fill out health diaries on a weekly basis. The blinding used in this study will eliminate the criticism of the earlier Canadian studies (Payment et al., 1991; Payment et al., 1997).

What Studies Should Follow The Water Quality Study?

Regardless of the outcome of the Water Quality Study, additional studies are needed to answer other key questions facing the water industry. Perhaps one of the most common questions for which there is currently no consensus is, 'Do small numbers of Cryptosporidium oocysts that are found in most surface water supplies cause human di sease?' (Robertson et al., 1998). The least number of oocysts studied in human infection experiments is 30 oocysts (DuPont et al., 1995). Five volun teers received this dose; one became infected, but none developed symptoms. Two volunteers received 300 oocysts and no infections or symptoms occurred. Even when seven volunteers received more than 1,000 but up to one million oocysts, only 5, or¡ 71 % , developed symptoms. The oocysts used in this study we re all Cryptosporidium parvum and viable, unlike those detected in source water A Positive Water Quality Study w hi ch are often neither viable nor Result C. parvum (pers. comm. , T Stinear). Several different approaches includIf the results of the Water Quality Study and similar o ther studies are ing epidemiological studies and molecpositive and establish that endemic ular biology are needed to resolve waterborne gastroenteritis is real, it will whether Cryptosporidium and other be essential to determine the organism/s parasites such as Giardia in drinking responsible. This is essential because the water are responsible for human disease. treatment processes necessary to elimi- The epidemiological study d esign has to nate endemic waterborne gastroenteritis be different from a randomised clinical will be different depending on the trial because the specific causes of cause. For example , if regrowth with gastroenteritis (e .g. Cryptosporidium or organisms such as Aeromonas is respon- Giardia) are less common than all causes sible, then additional chlorination will of gastroenteritis. However, a study be needed. Alternatively, if parasi tes known as a case- control study is ideally such as Giardia or Cryptosporidium are suited to studying specific pathogens. T he CRCWQT is currently in the the cause, additional filtration or even pilot stages of a series of case-control membrane filtration may be required. studies across Australia to assess if A Negative Water Quality Cryptosporidium and other pathogens that may be transmitted through drinkStudy Result A negative Water Quality Study ing water are currently cau sing unrecognised gastroenteritis. result does not mean that there is no Molecular biology has a significant endemic waterborne gastroenteritis. It contribution to make and has recently means that if it exi sts at all, it is too been used to determine if waterborne small to measure using a randomised outbreaks of cryptosporidiosis result clinical trial. From a practical viewpoint from contamination of water by human a randomised clinical trial such as the or cattle waste (Peng et al., 1997). Water Quality Study is unable to rule out endemic waterborne gastroenteritis Disease Surveillance if it represents less than 15% of all Disease surveillance is the constant community gastroenteritis. ongoing monitoring of disease within a R andomised clinical t rials, while community to ensure any abnormal extremely rigorous scientifically, are increases or outbreaks of disease are limited in their ability to detect uncom- picked up as early as possible. The mon diseases. However, the Water CRCWQT and Melbourne Water have Quality Study is sufficient to detect jointly funded a proj ect which aims to endemic waterborne gastroenteritis of improve the ability of the existing the magnitude that the previous four surveillance systems to detect waterstudies have reported (Payment et al., borne outbreaks of gastroenteritis. This 1991; Payment et al., 1997; Schwartz et fo rms part of a separate paper (see Padiglione in the next issue of Water). al., 1997; Morris et al., 1996). WATER SEPTEMBER/OCTOBER 1998

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References

H erwaldt B L (1 996) Cryptosporidiosis: An Outbreak Associated with Drinking Water D espite State- of- the- Art W ater T reatmen t. Ann Intern Med, 124: 5 , 459-68. H ealth Stream N ewsletter, CRCWQT, Program 1 Quarterly n ewsletter. Internet address: h ttp://www.med.monash.edu . au/epidemiology/ere H ellard M E , Fairley C K (1997) Gastroenteritis in Australia: Who , What, Where, an d H ow Much? Aust NZ J M ed, 27: 2, 147-9. Kramer M H , H erwaldt B L, C raun G F, Calderon R L, Juranek D D (1996) Surveillance fo r Waterborne Disease O utbreaks - United States, 1993-4. MM WR, 45, (SS-1 ), 1- 33. MacKen zie W N, H oxie N J , Proctor M E, Gradus M S, Blair K A, Peterson D E, Kazmierczak J J , Addiss D G, Fox K R , R ose J B , Davis J P (1994) A Massive O utbreak in Milwaukee of Cryptosporidium In fectio n T ransm itted Through the Public Water Supply. New Eng ] M ed, 331: 3, 161-167. M o rris R. D , N aumova E N , Levin R , Munasinghe R L (1996) T em poral Variation in D ri nking W ater Turbidity an d Diagn o sed Gastroen teritis in Milwauk ee . A m J Pub Hlth, 86: 2 , 237- 39. National Health & M edical Research Coun cil (NH &MRC) and Agriculture and R esource Management Council of Australia and New Z ealand . (1996).

Borgdorff M W , Koopman s M P G , Goosen E S M , Sprenger M J W (1995) Surveillan ce ¡of Gastroenteritis. Lancet, 346: 8978, 842-3. D uPont H L, C happell C L, Sterling C R., O khuysen P C , R o se J B , Jakubowski W (1995) The Infcc tivity of Cryptosporidium parvum in H ealthy Volun teers. N ew Eng} M ed, 332: 13, 855- 59 . Gold stein S T, Juranek D D R avenholt 0 , H ightower AW, Martin D G , MesnikJ L, Griffiths S D , Bryan t A J , R eich RR,

National Water Q uality Managem en t Strategy: A ustralian Drinking Water Guidelines 1996. Payment P E , Fran co E, Richardson L, Siemiatycki J (1991) Gastroin testinal H ealth Effec ts Associated w ith the Consumption o f D rin king W ater Produced by Poin t-of- U se Domestic R everse-Osmosis Filtration U nits . .{ippl En viron M icro, 57: 4 , 945-48. Paymen t P E, Siemiatycki J , Franco E (1997) A Prospective Epidemiological Study of

Due Care and Diligence Through the water quality research being u ndertaken by the CRCWQT the Australian water in du stry will have voluntarily carried ou t mo re epidemiological research than any other country including the fi rst double blind clinical trial, the Water Quality Study . In doing so it will h ave shown more due care and diligen ce than m any other industries worldwide.

Conclusion O ur natural advantages arising from th e adoption of guidelines rather than standards, a cooperative approach and insightful government has enabled the Australian water industry to steer a pragmatic, responsible, cost-effective and innova tive app ro ach to water quality. This approach incorpora tes molecular biology, epidemiology and p re-existing water quali ty parameters in o rde r to th oro ughly unde rstand the interaction between water quality an d human health. This approach seem s eminently more logical than relying on tigh tening acceptable levels of indicator o rganisms w hen w e are not sure that a significant health risk exists.

Gastrointestinal H ealth Effects D ue to the Consumption of Drinking Water. Intematj En viron Hlth R..es, 7: 5-31. Robertson B , Sinclair M , H ellard M , Fairley C. 1998 Cryptosporidiosis: What D o W e Know? Water 25: 4 , pp. 18- 19 . Peng M M , Xiao L, Freeman A R , Arrowood M J , Escalante A A, Weitman AC, Ong C S L, M acKenzie W R , Lal A A, Beard C B (1997) G enetic Polymorphism Among Cryptosporidium parvum Isolates: Eviden ce of T w o D istin ct H um an Transm ission Cycles. Em erg Infect Dis, 3: 4, 567-73. Schwartz J R , Levin R , H odge K (1997) Drinking Water T u rbidity and Paediatric H o spital U se for Gastrointestinal Illness in Philadelphia. Epidemiology, 8: 6 , 615- 20.

Authors Associate Professor Christopher (Kit) Fairley is H ead of the Infectio us

Di sease

Epidemiology

U n it

a¡n d

Dr Martha Sinclair is a Senior

R esearch Fellow in the D epartment of Epidemi ology and Preventive M edicine, M onash M edical School , Alfred H ospital, Prahran Vic 3181 , a partner in the Cooperative R esearch Centre fo r W ater Quality and T reatmen t.

APOLOGY Phosphorus Inputs to a Reservoir in Orange, NSW M H Chowdhury, D Al Bakri, July/August 1998 We regret that Figures 2 and 3 were misplaced. ~ so the legend fo r th e x- axes fo r the three graphs in Figure 5 sho uld have read Log susp ended solid load, Kg/d

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ADVANCED WATER TREATMENT WITHOUT CHEMICAL COAGULANTS M Muntisov, J Stewart, K Horlock

Abstract For the water supply of the small town of Trentham in Victoria (populati on 600), Coliban Water requi red more advanced treatment than that provided by conventi onal m eans beca use of taste and odou r problems and the need to provide surety against algal toxins. T he solution developed provides the requi red level of treatment w ithout coagulant chemicals by using a combination of advanced processes including microfil tration, ozonation and granular activa ted carbo n (GAC) filtrationpossibly the world's firs t applicati on of this process combination fo r drinki ng water. T he plant has performed well since commencing operation . T he ozone has removed colour down to the requi red levels, turbidity is very low after microfil tration and the GAC removes the taste and odou r in the water. Troublesome levels of manganese have also been removed. Compared to processes relying on chemical coagulan ts, the new process does not have to be fi nely tuned , is easier to control, has fewer handling and sludge problem s and produces less sludge and waste.

industry restructuri ng and was conThere is a growing resistance in the cerned about the periods of poor water gene ral community to the use of c hemi- quali ty and the complaints of discals in foods and drinks including tap coloured water and offensive tastes and water. T he vast majority of Australia's odours. Tenders were called for the design d rinking wate r treatm en t plants and construction of a new treatment routinely use chemicals such as metal coagulants, polymeric coagulant aids pla n t tha t woul d solve these water and alkali chemi cals to achieve the quality problems, destroy algal toxi ns and remove protozoan cys.ts . The necessary treated water standards. T he town of Trentham in Victoria successful tenderer was Mem tec Ltd has a population of 600 and is located (now part of U S Filte r Au stralia), with approximately one h our no rth of the assistance of Gut teridge Haskins & M elbourne. Its water supply is derived from springs w hich feed 'possibly the world's first two reservoirs w ith a combined capacity of 70 M L. T he raw water application of this process supply was previou sly chlo raminated p n or to delive ry t o combination for drinking Trentham. water' Typical raw water quality is set out in Table l. T he water can be characterised as being low in colour and Davey (G H D). The accepted treatment turbidity with moderate hardness and process was a unique combination of alka lini ty. Seasonal problems occur microfiltration, ozonation and granular with algal-derived tastes and odours, activated carbon (GAC) filtration which and iron and manganese levels are suffi- permitted satisfactory operation with ciently elevated to cause complaints of out the need for chemical coagulants under typical raw water conditions. To dirty water. Coliban Water, the responsible wa ter handle conditions outside the typical au thority, took over the Trentham range, particularly fo r colour, a polysystem in the recent Victorian water aluminium chloride dosing facili ty was

Introduction

WATER SEPTEMBER/OCTOBER 1998

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Clear water storage and GAC vessel at Trentham Reservoir

Ozone contact tank, GAC vessel and mlcroflltratlon feed tank

provided for short-term operati on unde r these circumstances.

under pressure to a pressurised ozone contact tank. Ozone is generated onsite from air and irijected at th e inlet to Description the ozone contact tank via a service A general schem atic of the treatment water strea m. The ozo nated water is th en plant is given in Figure 1. R aw water i s uniformly applied to an uptlow GAC pumped from the existing reservoirs to filter vessel with an empry bed contact a 25 kL tank at the treatment plant. time of 15 minutes, using coal-based T he m icrofil tration uni t is a US carbon. The GAC filter is backwash ed Filter/M emcor 16M10C using nominal · by a combinatio n of ozonated and 0 .2 micron pore size polypropylene treated water. GAC was hwa te r is hollow fibres. Automatic air/water collected in the microfiltration feed backwashing and clean-in-place system s tank and re-treated in the process. are provided. GAC filtered water is discharged to a T he microfiltered water is delivered 0.7 ML clear water storage. Provision Table 1 Raw water quality Parameter Turbidity (NTU)

Typical range 1-8.5

Table 2 Design Parameters Parameter

Design

Rated plant output

0.7 Ml/d

has been made fo r sodium hypochlori te dosing at the clear water storage inlet. The o utflow from the clear water storage is disinfected using the existing chloramination system. Some unusual features of the plant include: • full process reversibili ry. It is possible to alter the process seque nce and run ozonation/GA C ahead of njcrofiltration • a stabilisation period for the GAC filter immediately after backwashing to allow its performance to stabilise before it is brought back into service • automatic recirculation through the Table 3 Typical plant performance Parameter

Raw water

Treated water*

True colour (PCU)

4 - 20

Microfiltration f lux rate

135 l / m2.hour

Turbidity (NTU)

3.5

0.12

pH

6.5-8.9

Ozone generator

100 g/hour

Alkalinity (mg/L CaC03 )

32-71

True colour (PCU)

10

2.5

Ozone dose capacity

3 mg/L

Total iron (mg/L)

0.05-1 .5

Ozone contact time

0.6- 1.2

<0.05

5 minutes

GAC filter EBCT

15 minutes

Manganese (mg/L)

0.06

<0.01

Alumi nium (mg/L)

0.15

0.013

Noticeable

Nil

Manganese (mg/L)

0.05 - 0 .1

Hardness (mg/L CaC0 3)

27-48

Total organic carbon (mg/L)

2-6

Conductivity (µS/cm)

90-110

NTU = nephelometric t urbidity unit PCU = platinum cobalt unit

16

WATER SEPTEMBER/ OCTOBER 1998

GAC backwash rate

35 m/ hou r maximum

Clear water storage

700 kl

GAC = granular activated carbon EBCT = empty bed contact time

Iron (mg/L) C

Taste and odour

NTU = nephelometric turbidity unit PCU = platinum cobalt unit * based on on-site measurements


WATER GAC filter if the plant is off-line for more than a preset period of time to prevent the filter from going off A summary of the main plant design parameters is given in Table 2.

Bockwash

Backwash

I

Performance The plant has been in operation since March 1998. Experience with non- coagulant operation highlights the following significant advantages compared to treatmen t using chemical coagulation: • the process does not have to be finely tuned. T here is no dosing to be adj u sted either fo r coagulatio n or pH reduction. C hanges in the solids content of the raw water are automatically accom modated by the microfil tratio n uni t and its backwashing freq uency. The ozone system can operate under automatic redox control, ensuring maintenance of a small ozone residual on the contact tank ou tlet even under varying raw water conditions. W ith these two reliable steps ahead of the GAC, the efficiency o f its adsorption and biological func tions 1s unaffected • the process is easier to control. As a result of the above fea tures, control of the plant is particularly straigh tforward. There is no drop off in treated water quali ty under stop-start conditions or when c hanges occur in raw water quali ty • less chemical handling issues. T here is a limited reliance on chemicals so chemical inventory levels do not need ca reful monitoring, and ch emical storage and delivery requirements are minimised • less sludge production. No coagulant sludges are produced. The only solids in the wastes generated are those present in the raw water, and pH adj ustment is not required p rio r to return o f settled washwater to the source reservoirs. Typical performance achieved during initial operation is set out in Table 3.

j

Conclusion The successful implementation and operation of the T rentham water treatment plant using a unique three- step

Ozone

Mtcroflltratlon Unit

feed Tonk

GAC F~e<

Contact Tank

Coo Wote< Souce

Storage

ReservOlrs

Figure 1 General schematic of the treat ment plant

process of m icrofiltratio n , ozonation and GAC filtration has demonstrated that high quality treated water can be produced wi thout chemical coagulants under appropriate conditions. T he application of this no- coagulant process on other Australian waters may be particularly advantageous under the following water quality conditions: • presence of Giardia/ Cryptosporidium • presence of tastes and odours • presence of algal toxins

Costs The const ruction cost of the Trentham plant was around $700,000, including a 700 kL clear water sto rage tank , and con necting pipework to and fro m the existing reservoir ou tlet and delivery pumping station. Operating costs have not yet been fully defined but are estimated to be in the order of$24,000 per year including labour, parts, maintenance and membranes. Ann ual treated water prod uction is in the order of 130 ML.

D

Ozone

• low to moderate algal mass • low to moderate true colour.

Authors Michael Muntisov 1s GH D's National Manager for Water Quality and Treatment based in Melbourne, Jenny Stewart is Project Manager, Coliban Water and Keith Horlock is Municipal Applications Engineer with US Filter.

+ Municipal Wastewater Treatment

+ Water Reclamation Systems + Industrial Cooling Water + Aquaculture and Marine Life Support Systems Mr John Chalmers Managing Di rector

+ Food Processing

Industry

Mr Philip Barlow Technical Director

IDl11C5 WATEB'l'EC HEA D OFFICE: Brisban e 31 Benronalds Street SEV ENTEEN MILE ROCKS QLD A ust 4073 Ph (07) 3279 1 B88 Fax: (07) 3279 1790

Sydn ey Suite 1, 895 Pacific Highway PYMBLE NSW Aust 2073 Ph (02) 99B3 1944 Fax: (02) 9983 1787

Pty Ltd

Melbourne Unit 11, 993 North Road M URRUMB EENA VIC Aust 3163 Ph (03) 9570 8366 Fax: (03) 9570 8399

WATER SEPTEM BER/ OCTOBER 1998

17


WATER

ARSENIC REMOVAL FROM DRINKING WATER M Chapman Summary Arsenic occurs at significant concentrations in some bore waters drawn from arsenic- rich geological formations. To achieve safe drinking wate r quality, its conce ntration m ust be reduced. Coagulation- sedimentation-filtration is the conventional means, but there are complica tions. This technical n ote discusses improvements in the performance of a rural Victorian plant.

Treatment A range of targets has been set fo r arseni c in drinking water: • USEPA 0.05 mg/L (enforceable limi t) • WHO 0.01 mg/L (guideline) • NHMRC/ARCANZ 0.007 mg/ L (guideline) The range reflects di fferent assump-

tions regarding the toxicology of arsenic, and its significance w ith respect to human health. The USEPA crite rion is based on non-cancer fac tors and is enforceable. The WHO and Australian limits are not enforceable by regulation , and take into accou nt recent epidemiological stu dy results suggesting that ingestion of arsenic at relatively high concentrations (>0.3 mg/ L) is associated with skin cancer. Significant u ncertainty remains as to the appropriate way to extrapolate th e obse rved effects at m uch higher arsenic co ncentrations to determine a 'safe' long- term drinking water criterion.

Performance R ecen t assessment of an existing poo rly pe rforming arsenic removal

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plant in Victoria u sing conventional treatme n t illustrates some important issues to be addressed to ensure reliable performance. The water is drawn from a deep bore in volcanic formations. Arsenic removal increases if all arsenic is in the pentavalent (V) fo rm. Arsenic in the trivalent (III) fo rm can be more difficult to remove. A suitable cheap oxidant to maximise the pentavalent form of arsenic is chlori ne. The removal of arsenic from water involves a complex adsorption- coprecipitation m echanism which is sensitive to pH. As the reaction pH increases the dose of flocculant mu st be increased. Best results occur ·when the pH is less than 8. However, release of dissolved carbon dioxide from the bore water due to depressurisation and aeration during the floccu lation process can result in a variable and higher than expected pH, and this must be controlled. Fe rric salts are more effective than alum or polymers as they can operate over a wider range of pH and form relatively insolu ble complexes with arsenic. T he ratio of ferric salt:arse nic must exceed a critical value to ensure that all arsenic is complexed with the iron. R eliably achi eving arsenic concentrations of 0.05 mg/L o r less in the treated water requires effective preoxidation and complete remov:tl, usually by filt ration, of the fe rric hydroxide and th e co-adsorbed arsenic floe generated in the flocculation process. T he final filtered water turbidity shou ld be less than 0.5 N TU, and preferably less than 0.1 NTU. R everse osmosis and ion exchange processes can also be used, bu t are often more expensive. A recent publication describes a development at the T echnical University of Berlin using granular ferric oxide in a fixed bed reactor which reduced the co ncentratio n to less than the WHO guideline (Driehau s et al., Jnl Water Supply and T echnol ogy, Aqua 47 (1) Feb ru ary 1998) .

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Author M ike Chapman is a water treatment consultant in the M elbourne office of CMPS&F.

18

WATER SEPTEMBER/OCTOBER 1 998


~

WATER

BACTERIAL REGROWTH POTENTIAL QUANTITATIVE MEASURE BY ACETATE CARBON EQUIVALENTS N Withers, M Drikas Abstract

d issolved o rga nic carbon (DOC) removal an d dec rease th e potential fo r regrowth problems in the distribution system.

There is no single preferred me thod fo r determining biodegradable organic carbon. The bac terial regrowth potential (BRP) is a simple meth od whi ch Key Words provides direc t m easure m ent o f a Bac terial regrowth po tential (BRP), wate r's ability to suppo rt bac teria l ass imi lable organi c ca rbon (AO C), grow th . T h e m eth od m easures the acetate carbon equival ents inc rease in bacterial biomass by recording th e c hange in turbidity over time. Introduction From th e growth curve produced the R ecu rre n t problem s w ith tastes, growth fac tor and growth rate can be de termined. W erner and Hambsch odou rs and bac terial regrow th in distri(1986) have fo und that water w ith a bution systems have focused interest on growth fac tor <5 and a grow th rate investigating th e factors which stimu<0. 1 h- 1 can be classi fied as biologically late bacterial growth. O ne of the key nutri ents responsible fo r bacterial stable. growth in distribution syste ms is th e Deionised w ater, raw and treated waters were spiked wi th a range of biodegradable component of organic acetate conce n trations. T he re was a carbon. This biodegradable frac tion of good correlation between increase in organic carbon is u sually present at ve ry biomass as measured by turbidity and low levels in the water di stribution acetate co ncentration fo r each water. sys tem. These low concentrations of The slope of the curves vari ed from 1.0 organics cannot be detec ted accurately to 1.8, with the average slope being 1.5. by chemical analyses. Th is has resulted Acetate carbon equivalents were the n in the development o f seve ral microbicalculated for each wate r u sing the ological assays, as well as techniques average slope. The results in dica ted Stationary Phase that Australian waters with acetate carbon equivalents below 80 Âľ g C/L Death phase were equi valen t to sa m ples w ith growth factors <5 and can be classiExponential growth fied as biologically stable. Providi ng a ca rbon valu e allow s o perators a Lag phase bette r parame te r to assess plant performan ce. This makes it easier to Incubation time de termine w hether operating param eters need to be altered to optimise Figure 1 Bacteria growth cycle

based on measuring changes in DO C over a long i ncubatio n peri od. R esearchers have noted that biomass-based measure me n ts will always be lowe r than methods based o n DOC measurements, as the p ortion of the DOC that can be conve rted to cell mass is smaller than the fraction which can be mineralised (Frias, Ribas and Lucena, 1995). There are seve ral biomass- based m ethods. T hese methods diffe r both in the type of inoc ulum used and the pa rameters measured. The inoc ulum may be either known bacterial strains o r indigeno us bac te ria from t he wate r sample. Th e parame ters measured include colony formi ng units (CFU)/ m L, Ade nosine triphosphate (ATP) con ce ntration and change in turbidity. The different me thods make it difficul t fo r direct compari sons of the bio degradable carbon to be made. Operators are inte re sted in using the biodegradable carbon concentration as an additional parame ter to help optimise water treatment processes. The bacterial regrow th potential (BRP) method developed by W erner et al. (1986) directly m easures the p otential to supp ort the bac terial grow th of a particular water. From the growth curve produ ced the grow th rate (the slope of the curve during exponential growth) w hich correlates to the substrate quality and the growth factor (the difference in biomass from the beginning and the WATER SEPTEMBER/ OCTOBER 1998

19


WATER end of the experiment) w hich correlates to the substrate quantity can be determined. It was determined that waters with a grow th factor <5 and a growth rate <0.1 were biologically stable (Hambsch and W erner , 1994). The BRP m ethod was the preferred m ethod for this study as it u ses the indige nous bacteria from the water sample w hich are well adapted to the nutrients present and provides a more direct m easure of bacterial regrowth in a distribution system. Its parameters, grow th factor and growth rate provide useful information on bacterial grow th. Work has been carried out investigating the BRP of a variety of waters from differen t w ate r sou rces from around Australia (Withers et al. , 1996) . These results w ere compared with the work carried out by W e rner and Hambsch (1994). The results fo und that a majority of trea ted and raw surface waters were biologically unstable under Australian conditions. In comparison, most groundwate rs were fairly stable and these results agreed w ith the work carried out in Germany.

w ithin 24 ho urs. All glassware was sterile and wash ed in sodium hydroride solution. The water sample was filtered through pre-rinsed glass fibre filters to remove large particulate m atter. All filters u sed were pre- rinsed w ith 1 L of Milli Q water to prevent the leaching of DO C into the water samples . An ino rganic nutrient salt solu tion was then added to the water sample in the ratio 1: 11 to ensure that A OC was the limiting nutrien t. The sample was st erile-filtered throu gh pre-rinsed polycarbonate membran es (0.2 mm Pore tics). Polycarbonate m embran es were used in preference to cellulose acetate membranes due to the possibility of carbon leac hing. A 250 -mL aliquot of sample was placed in the 300 mL cuvette and inoculated with the bacteria w hich were washed off the polycarbonate membrane and resusp ended in isotonic saline solution. The volume ofinoculum was determined by turbidity m easurements and the ideal bac terial concentration was be tween 1 x 104- 5 x 104 cells/mL. Each cuvette received the same volume of inoculum. The samples were then incubated at 20° C fo r a mini mum of 72 hours w ith turbidity measurements taken every 30 minutes. Turbidity was measured at 12° forward scattering .

Study Aim The aim of the current work was to use standard acetate additions in a variety of waters to determine whether a relationship co uld b e es tablish ed between turbidity and acetate carbon and whether it was possible to link an ace tate carbon equivalent to grow th factors for wa ters. T hjs could the n be used to determine the concentration below which a water was biologically stable. Acetate was chosen as it is a simple organic compound easily biodegraded by microorganisms and has been used as the basis for carbon equivalent comparisons by other researchers (van der Kooij et al. , 1982).

Method

Growth Curve The growth curve produced at the end of each exp eriment was divided into the lag phase, th e expo nential growth phase and the plateau phase (see Figu re 1). From this curve the growth rate (slope of the growth curve during the exponential growth phase) and the growth factor (increase in biomass) can be determined. T he growth rate can be correlated to the quality of the substrate being used, while the grow th factor correlates to the quantity of substrate being used.

In the BRP method (Withers et al. , 1996) samples were collected in glass bottles, stored at 4° C and analysed

Acetate Solutions The acetate spikes were m ade up from a 29.3 mg/L carbon stock solution ,

and dilutions ranged from 1:100 000 to 1:1 0. The stock solution was made up with Milli Q water. Standard additions were added to either Mjlli Q wate r, raw or trea ted wa te rs from different Adelaide metropolitan treatment plants.

Results High Purity Water High purity water was spiked with a range of acetate con centration s from 0 .00029 to 2. 9 mg C/L and these growth curves are shown in Figure 2. As high purity water i s the only water w hich did not have a natural consortia of bacteria, these samples were inoculated with bacteria fro m different water sources. Unspiked high purity wate r produced only a small amount of growth. The growth curves for the differeRt acetate concentrations in high purity wate r sh ow ed go od re producibility . Slight differences in lag phases between expe riments w ere probably due to the different inocula used in each experiment, since bacteria vary in their ability to assimilate carbo n compou nds. In some of the standard addition s at very low acetate concentrations, the lag phase increased up to 40 h ours, which was similar to the lag phase for unspiked high purity samples. From the w ork using the low concentrations, it appears that the sensitivity of th e me thod is reliable down to an acetate concentration o f 0.029 mg C/L. In previous research , to de termine w hether all the biodegradable carbon has been used, Servais et al. (1987) reinoculated a water sample and added a new carbon source such as gluco se. N ew bacterial growth resulted, but the DOC concentration return ed to the concentrat ion prior to the gluc ose addition, showing that only refractory o rganic matte r was present. This suggests that once bacterial growth has reached a plateau further decreases in DOC are minimal.

10

10

4.9 x 10' TCN/ml 2 .0 x 106TCN/ml

1a

1.4

d' en

x 1O&TCN/ml

1.1 x 10' TCN/ml

~ >,

~

:C

(/)

E

0.

E

a.

? ~

0 .1 a -

- -~-

.. ----::-'=:-

j,•====:;;;:::::;;;~ •· ..... •• ..---· - - acetate 0 .00029 mg/L

~ 0.01 , (8.6 -9.3) x 10 TCN/mL 1-

'

- - acet 0.0029 mg/L -------- acetate 2.9 mg/L

:

0. 1

L-- - --.:?"

-~ -e

:2

-

.=

- - raw Myponga 2 ,9 mg/L acetate + 2 .9 mg/L acetate

0.01

-

raw Myponga 0 . 29 mg/L ace tate + 0 .29 mg/L aceta te

-

Milh Q + 2.9 mg/L ace ta te

- - MilliQ

treated 2 .9 mg/L acetat e + 2. 9 mg/L acetate

1E-3+-~~~~-~~~~~~-~~~~~~

0

10

20

30

40

50

60

70

80

Incubation time (hrs)

Figure 2 Bacterial regrowth potential for high purity water with different acetat e spikes

20

WATER SEPTEMBER/ OCTOBER 1998

raw Myponga , no a dditional sp ike

20

40

60

80

100

120

140

160

180

Incubation time (hrs)

Figure 3 Bacterial regrowth potential f or Myponga waters spiked with acetate. Samples reinoculated and respiked in the plateau phase


WATER longer for the lowest and highest acetate concentrations. These differences may be due to different rates of utilisation of acetate by bacte ria, depending on whether they need to initiate enzyme production for its breakdown. Other reasons for differences in the lag phases may be due to interactions between the acetate, bacteria and other natural organic matter (NOM) present, w hich may cause inhibitory effects on bacterial growth. T he growth rate in the BRP method is dependen t on the substrate quality. As acetate was the maj or source of carbon in this work, the growth rates were very similar between O.1-0.3. T he small differences seen between waters could be due to the background NOM present. The Myponga and M organ samples had slightly higher than average growth rates. The unspiked samples fo r all the raw and treated waters showed much lower growth rates of between 0 .01 and 0 .2.

Raw a nd Treated Wat ers The raw waters were sampled from the River Murray and several reservoirs in metropolitan Adelaide. The reservoirs have different types of catchments: H ope Valley is located in a residential area, Myponga and Barossa in agricultural regions and Happy Valley in an area of mixed uses. All the treatment plants except Myponga are conventional treatment plants using alum as the primary coagulant (Myponga is a dissolved air flotation plant). T he Anstey H ill plant is the o nly plant to use prechlorinated raw water. T here was some variability in results between the raw and treated waters. Raw water did not always produce the largest increase in bio mass. This may be due to seasonal changes in water quality and the types of natural organic matter present. Raw water usually has a greater proportion of higher molecular weight organic compounds. During treatment these larger compounds may be broken down by oxidation into smaller, more assimilable compounds w hich are more readily biodegraded, promoting increased growth in the treated water. Treatment also alters the ratio of organics present in the finished water. The acetate spikes produced similar growth curves in the different waters. T here was an order of magnitude difference in biomass increase between the 2.9 and 0 .29 mg C/L acetate spikes. The variability obse rved in the differe nt water sources would be due to the different levels and types of o rganics present. In the treated waters Myponga, a highly coloured water, had the highest growth factors and Hope Valley the lowest. None of the water samples showed any secondary growth , suggesting that the AOC present in the raw and treated waters was biodegraded at the same time as the acetate. There was some variability of the bacterial response in the different waters which were spiked with acetate. Some waters had very similar lag phases, whilst fo r others the lag phase was

The work of Servais et al. (1987) was repeated using acetate. The additio n of inoculum without an acetate spike produced no additional growth, suggesting that all the AOC had been used (see Figure 3). The samples which were respiked and reinoculated during the plateau stage all showed further growth, with the exception of the highest acetate concentration of2.9 mg C / L in the treated water. For the samples with the highest acetate spike, growth appeared to reach a maxim um level of around 6 ppm SiO 2 turbidity. If the initial growth curve did not reach this level , when the sample was respiked and reinoculated the additional growth reached this level. A high purity water sample was not initially spiked with acetate, but was spiked with 2.9 mg C/L after growth reac hed the plateau phase. T he additional growth produced did not reach the same level and the total cell nu mber (TCN) cou nts were lower than the samples w hich we re originally spiked at this co ncentration. This suggests that there may have been so me other li miting nutrient. T o determine whether another nutrient became limiting at the highest acetate concentration, after the growth curve reached the plateau stage two duplicate samples were reinoculated and respiked and additional nutrient solu ti on was added to o n e of the samples. This ensured that no other nutrient wou ld be a limiting facto r. There appeared to be no real difference in growth between the two samples, with both having no additional growth once they reached the plateau stage (see Figure 4) . At the highest acetate spike 2.9 mg C / L no addi tional growth occu rred once the plateau was reached. T his suggests that at high acetate concentrations fu rther bacterial growth was in hibited by the buildu p of toxic metabolic waste products o r that the disso lved oxyge n had decreased to levels which wou ld not sustain the population.

Slopes and Regression Coefficients T here was a strong linear relationship in Milli Q water between the increase in turbidity and the acetate concentration. The slope fo r all the standard acetate additions up to 2.9 mg C/L was 1.56 with a regression coefficient of 0.959. The slope was then calculated fo r the standard acetate additions in Milli Q at the lower end of the range, w hich would correspond more closely to the range in natural water samples. The slope was m uch lower, 0.9 18, with a regression coefficie nt of0.923. Werner et al. (1992) calculated a slope of 2.3 when the change in DOC was plotted against the change in t urbidity fo r standard additions in Milli Q water. In the current work the slope was determined by plotting the change in turbidity against the acetate concentration, since the change in D OC was unable to be accurately determined. T his difference in the slope may also be due to differences in sample size, as Werner et

6

10

Slope= 1 .5

R = 0 .91 6 N = 1 40

5

/

d' u'i

/

E a.

.e

ct' en

4

E

.ea.

3

- - Acetate 2 .9 mg/L no nu trient

~

2

...... Aceta te 0.29 mg / L nutrient

I-

0.1

.~

.

""O

:.c :i I-

. r -Samples were rein oculated and respiked w ith acetate

,..--/'

¡-¡¡ -~

- - Acetate 2.9 mg/L nu trient

0 .01

:,

Acetate 0.29 mg/ L no nutrien1

<l -

1 '

/

: I

I

/ i .. . 10

20

30

40

50

60

70

80

Incub ation time (h rs)

Figure 4 Bacterial regrowth pote ntial f or Mill i Q water un der different conditio ns

0

I

0.0

I

0.5

1 .0

1 .5

2 .0

2.5

3.0

3 .5

Ace tate co n centratio n mg C/L

Figure 5 Standard acet ate additions for al l waters tested

WATER SEPTEMBER/ OCTOBER 1998

21


WATER Table 1 Slopes and regression coefficients for raw and treated waters Source

Raw Slope

R Sample no.

Treated Slope

R

All waters

MilliQ

Hope Va lley

Happy Va lley

Barossa

1.5 0.916 140

1.56 0.96 49

1.168 0.998 6

1.211 0.99 6

1.03 0.997 3

1.337 0.956

1.27 0.895 8

1.25 0.704 9

Sample no.

14

Little Para

Myponga

Anstey Hill

1.109 0.944 7

1.484 0 .858 8

1.65 0.93 21

Morgan

1.727 0 .99 3

1 .83 0.927 5

1.42 0.917 4

to their biological stability, it was de termined that an acetate carbon equivalent Water Growth Acetate carbon Growth Acetate carbon value of 80 mg/L corresponded to a factor equivalent factor equ ivalent factor of 5. growth <5 mg.IL <80 >5 >80 There was quite a large amount of 11.7 215 Hope Valley raw variability in the results for the different 10.9 197 waters. The raw su rface waters all had Hope Valley treated 3.3 46 7.7 133 acetate carbon equivalents greater th~n 3.1 41 8.3 146 80 mg/L and would be classed as Happy Valley raw 5.8 96 biologically unstable. Trea ted water 5.5 90 samples had much more variable water 30.0 580 quality. D epending on the season and 26.3 507 whether there had been recent rainfall, Happy Va lley treated 3.0 40 15.7 293 the acetate carbon equivalents varied in 2.9 13.9 38 259 the treated waters. Only a few of the Myponga raw 6.0 100 treated water samples had acetate 7.7 133 carbon equivalents below 80 mg/L and 5.5 90 would be classified as biologically 3.8 Myponga treated 56 6.1 102 stable. Even at these low levels, the 2.3 33 8.2 145 waters showed detectable amou nts of 15.7 293 bacterial growth by the BRP method in Anstey Hil l treated 4.3 67 11.2 205 the laboratory environment. Milli Q 10.1 183 water still produced small amounts of growth, although these samples all had Mt Gambier bore 4.1 62 5.5 90 3.9 6.3 58 105 acetate carbon equivalents below 80 mg/L. Seasonal variations in water Pinnaroo Bore 1 3.6 51 quality influence the types of organics 3 .0 41 present in the raw water. For example, MilliQ 4.0 39 a Happy Valley sample during a period 3 .5 49 of consiste nt water quali ty had a concentration of 38 mg/L, which al. (1992) used only five samples. which were lower for the raw water increased to 293 mg/L acetate carbon Calibration curves were determined samples. H oweve r, afte r treatment, equivalents after rain. for the raw and treated waters. water contains a higher proportion of . When comparing th ese- acetate Individual slopes and regression coefii- lower molecular weight organics due to carbon equivalent concentrations with cie nts for each water source are shown removal of high molec ular weight the results obtained by other in Table 1. When comparing t he organics by flocculation and the bacteria researchers, the results of this research individual slopes, the results ranged present should be able to assimilate show similar trends. The other metho ds from 1.03-1. 83. The waters w ith lower more efficiently the smaller molecular which calculate AOC use pure cultures average DOC levels tended to have weight organic compounds in th e compared with the indigenous bacteria slopes at the lower end of the range, treated wate r. There may also be used in the Werner method. This may while the more highly coloured waters increased utilisation of the acetate due influence t he final concentrations had slopes at the upper end of the range. to a synergistic effect with the lower obtained. T he average slope for all the waters molecular weight o rganics in these Van der Kooij (1990) looked at a samples was 1. 5 with a regression waters. numbe r of very low DO C waters and coefficient of 0.9 (see Figu re 5) . H ope Acetate Equivalents found that wa ters wi th an AOC Valley and high purity water had high Acetate carbon equivalents can be co nc entration below 10 mg acetate regression coefficients wi th a large determined for all the raw and treated carbon equivalents/L were biologically sample number, and th ese samples waters by dividing the change in turbid- stable. Bradford et al. (1994) fou nd that showed the best correlation between ity for the unspiked water samples by bacterial growth did not occur in waters acetate concentration and ch ange in the average slope (1. 5) . Some of these with AOC concentrations less than 54 turbidi ty. T he raw waters tended to values are shown in Table 2. mg C/L. LeChevallier et al. (199 1) have slightly smaller slopes than the Hambsch et al. (1992) determined determined that waters with a total treated waters, with the exception of that water with a growth factor of less AOC concentration b elow 100 mg C/L the Morgan sample. This difference in than 5 was biologically stable. When the produ ced less than 1% bacterial slope may be due to sample numbers, waters tested were classified according growth. Bradford et al. (1994) found Table 2 Acetate carbon equivalents mg.IL

22

WATER SEPTEMBER/ OCTOBER 1998


WATER 0.5-31% of the total D OC was assimilable, while van der Kooij et al. (1989) fo und much lower levels: 0-4% of the total DOC was assimilable. D epending on the water so urce, AO C concentrations vary in surface an d ground waters. Bradford e t al. (1994) obtained surface wate r AO C values of approxim ately 100 m g C/L, which seasonally increased to over 250 m g C/L. Treatment wi th ozone increased th e AOC concen tration to over 700 mg C /L, but subsequent treatm ent with GAC lowered the concent ration to less t han the raw wate r conce ntration. The surface water results obtained in the curren t research agree with the results obtained by these researchers. Treated waters ranged from 36- 266 mg/L, with several waters being classed as biologically stable at certain times of the year. T he raw waters tended to have slightly highe r acetate carbon equivalents, wi th no raw water being classed as biologically stable. T his work suggests that expressing BRP results as acetate carbon equivalents is very useful and that u sing these in conju nction with other data such as temperature, disinfec tant residuals and BRP info rmation suc h as grow th facto rs and growth rates would allow plant operators to optim i se AO C re m oval and produc e a biologically stable water.

Bestimmung der Verkeimungsneigung von Trinkwasser, Von Wasser 65, pp. 257-270. Werner P and Hambsch B (1986) Investigations on the Growth of Bacteria in Drinking Water War. Supply 4, pp. 227-232. Werner P and H ambsch B (1992) Experiences with the Measurement of R egrowth Potential in Drinking Water T reatment in Eastern Germany, Draft for German-Israeli Worksho p, Autumn, Karlsruhe. Withers N and Drikas M (1996) Bacterial R egrowth Potential in German and Australian Waters, Water 23 (4) pp. 59-62.

H obbie J E, D aley RJ, Jasper S (1977) Use of N uclepore Filters fo r Counting Bacteria by Flu orescence Microscopy, Applied and Environmental M icrobiology, 33 (5) pp. 1225-1228. LeChevallier MW, Becker WC, Lee R G and Schorr P (1991) Application of Biological Processes to C urrent T reatment Operations, Proceedings AWWA Water Quality and Technology Conference, Orlando Florida, pp. 11 29- 1164. Servais P , Billen G, Hascoet M -C (1987) D etermination of tbe Biodegradable Fraction of Dissolved O rganic M atter in Waters, W ar. Res. 21 (4) pp. 445-450. van der Kooij D , Visser A, Hijnen W A M (1982) D etermining tbe Concentration of Easily Assimilable Organic Carbon in D rinking Water, J o umal A WWA 74 Oct pp. 540-545. van der Kooij D , H ijnen W A M and Kruitbof J C (1989) The Effects of O zonat ion , B iological Filtration and Di stribution on the Concentration of Easily Assimi lable O rganic Carbon (AOC) in D rinking W ater Ozone, Science and Engineering 11 , 297-31 1. van der Kooij D , Hijnen W A M (1990) Criteria fo r D efinin g th e B iological Stability of D rinking Water as D etermined w ith AO C Measuremen ts. In Technology Conference Proceedings of Advances in Water Analysis and T reatment, AWW A Water Q uality and Techn ology Confe rence, 11-15 Nov, San Diego, Calif Werner P (198 5) Eine M ethode zur

Aut hors Naomi Withers is a R esea rch Office r at the Australian Water Quali ty Centre in Adelaide, P rivate M ail B ag, Salisbury SA 51 08 . Sh e graduated from Deakin University w ith a BSc (H ons) in Mic robiology and has a M aster of Envi ro nmental Stu dies fro m the University o f Adelaide. Mary Drikas is the Senior C hemist of the Wate r Treatm en t Unit of the Au stralia n W ater Q uality Cen tre , a position she has held since the unit was fo rmed in 1987. She has a BSc (H ons) from Adelaide University and a Postgraduate Dip lom a in Analy tical C hem istry fro m the University of South Australia.

Conclusion T he results of this i nvestigation have shown that acetate carbon equivalents can be related to growth factor by using an average slope value to calculate the acetate carbo n equ ivalents of diffe rent waters. It appears that they are a suitable m ethod of expressing the assimilable carbo n concen tratio n in diffe rent waters. T he current findings are similar to the work that has been carried ou t overseas.

References Bradford SM, Palmer C J , Olson B H (1994) Assimilable Organic Carbon C o ncentratio ns in Southern C alifornia Surface and G roundwater, W ar. Res. 2, pp. 427-435. Frias J, Ribas F, and Lucena F (1995) Comparison of Methods fo r the M easurement of B iodegradable O rganic Carbon and Assimilable Organic Carbon in W ater, W at. R es. 29 (12) pp. 2785-2788. Hambsch B, Werner P and Frimmel F H (1992) Bakterienvermehrungsmessungen in Autbereiteten Wassem Verschiedener H erkunft, A cta H ydrochim H ydrobiol 20 (1) pp.9 -14. Hambsch B , Werner P (1994) Bacterial R egrowth Potential (BR.P) of Drinking Water as a Function of W ater Q uality and Re tention Time, Internatio nal Sem inar in B io degradable Organic Matter, M o ntreal, 16 June 1994.

SPECIALISING IN ENVIRONMENTAL SERVICES ..,.. Environmental AudiVSite Investigations ..,.. Contamination Assessment & Remediation ..,.. Environmental Risk Assessment ..,.. Hazardous/Industrial Waste Management ..,.. Solid Waste Management ..,.. Information Management ..,.. Environmental Impact Statements ..,.. Environmental Management Planning & System Development

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WATER SEPTEMBER/ OCTOBER 19 98

23


WATER

A New Method for Analysing Off Flavours in Drinking Water D Graham, K Hayes Introduction

required for SPME is also less Ta ble 1 Comparison of CLSA and SPME (50 mL compared with l000mL Analysis of taste and odour or MDL (ng/L) MDL (ng/L} Odour threshold for CLSA). The more rapid 'off' flavours in drinking water CLSA SPME concentration (ng/L) time offerred by SPME analysis supplies has been carried out by a 0.5 1.6 MIB 5 is a d istinct adva ntage when variety of methods over the geosmin 0.2 0.6 4 responding to operational n eeds yea rs. T he Australian Wate r 0 .04 0.07 TCA 0.08 of water treatment plants during Quali ty Centre (AWQC) has MDL = Method detection limit off flavour episodes. had a long involvement with In other applications, SPME taste and odour analysis in both a has been successfully used to detector and an H P7673 autosampler research and commercial testing capacgenerate adsorption iso the rm data for ity. At AWQC, closed loop stripping for p rocessing calibration standards and powde red and granular activated solvent blanks. analysis coupled with gas chromatogracarbon. It has also been used to evaluate the analytical Parameters influencing phy/ mass spectrometry (CLSA- GC/ the efficiency of vari ous activated MS) has been used extensively as an pr?cedure _"".ere investigated initially carbons tendered for use at water treatMilhQ water (Millipore usmg analytical tool for a range of taste and ment plants in South Australia. odour compounds. Three particularly Corporation) spiked with known T he successful use of SPME for quantities of geosmin, MIB and TCA. poten t compounds, geosmin, 2analysis of M IB, geosmin and TCA has These parameters included the sample methylisoborneol (MIB) an d 2,4,6prompted furthe r investigations and trichloroanisole (TCA), are quantita- volu me , extraction time, extraction method development for a number of temperature, and comparison of saltingtively analysed on a routine basis. These other off-flavour compounds relevant compounds are responsible for the ou t agents and their most effective to the water industry. Initial results common grassy/earthy, musty/earthy, concentrations. The optimised method from this work are very promising. m usty/ medicinal taints fou nd in d rink- was then validated using raw water from ing water (Hayes et al. , 1996) an d the Myponga R eservoir, Adelaide, to NATA Accreditation account for most of the off flavour assess the applicability of the method for The _Australian Water Quality episodes experienced in Sou th Australia natural water containing typical Centre 1s the only organisation in of inorganic solu tes and elevated levels and elsewhere. Australia to be NATA-registered for Recently, an alternative to CLSA has organic carbon. the analysis of MIB and geosmin by become available for analysis of these Results and Discussion CLSA. After validation of the SPME compounds, using the relatively new T he re su lts demonstrated that th e method in October 1997, NATA registechnique known as solid phase is a genuine alternative to tration was expanded to include analysis m ethod microextraction (SPME). SPME is a of MIB and geosmin by SPME. simple technique offering significantly CLSA for a number of applications. The redu ced sample processing time detection limits were below the odour References compared to CLSA. It is less labou r- th reshold for each of the compounds Hayes K P, Graham D K, Simpson K L, intensive and rivals CLSA for sensitivity studied (Ito et al., 1987; Tuorila et al. , Stockham P C (1996) Off-flavours in at a lower cost. This report outlines the 1980; Young et al., 1996) and rivalled Drinking Water: Experiences of A South application of SPME to the analysis of CLSA for sensitivity (see Table 1). D ata Australian Water Authority. T echnical from the validation work demonstrated Proceedings of 10th IWSA-ASPAC off flavours in drinking water. that the method was sensitive and Regional Conference and Exhibition, reliable over a wide co nce ntration H ong Kong., Vol.1, 189-197 Materials and Method range. The performance data shown in Ito T, Okumura T and Yamamoto M (1987) In this application of SPME, volatile T able 2 are from 10 replicate analyses 2-Methylisoborneol and Geosmin Contaste and odour compounds are performed at co ncentrations approxicentrati on in Drinking Water and adsorbed from the headspace air above a mating the lower and upper 10% of the Sensory Test. Second International water sample onto a fused silica fib re working calibration range. Symposium on Off-flavours in the Aquatic Environment, Kagoshima,Japan, coated with a polydimethylsiloxa ne T he total analysis time per sample by O ctober 12- 16. (PDMS) stationary phase. The com- SPME is approximately 50 m inutes pounds are then quantitatively analysed (compared with two hours for CLSA) Tuorila H , Pyysalo T, Hirvi T and Venilainen A K (1980) Characterisation of Odours in by thermally desorbing the fibre in the and the volume of sample volume Raw and Tap W ater and Their Removal inj ec tio n port of a gas chromatoby Ozonation. Vatten 3, 191- 199. graph/mass spectrometer (GC/MS). Young W F, Horth H , Crane R , O gden T Table 2 SPME performance data T he SPME apparat us (available and Arnott M (1996) Taste and Odour Spike Mea n Std. Dev. commercially through Supelco) consists Threshold Concentrations of Potential (ng/L) (ng/L) (ng/L) of a manual holder with a depth gauge Potable Water Contam.inants. W at. Res. 30, 331-340. MIB 16.2 15.6 0.6 and plunger, to which an interchange121.2 1 27.3 3.0 able fib re assembly is attached. For this Authors application, a fibre coated with 100 Âľ m 15.8 geosmin 14.8 0.6 PDM S was used, although other phases David Graham and Keith Hayes 118.2 115.2 1 .5 are available. The GCf MS system are members of the Australian Water TCA 1.9 1 .7 0.1 consisted of a Hewlett- Packard 5890 Quality Cen tre, Private Mail Bag 3 11.7 10.5 0 .4 Salisbury SA 5108. ' series II GC, HP5971A mass selective 24

WATER SEPTEMBER/OCTOBER 1998


BOOKS

CRC for Catchment Hydrology Industry Reports $20fromAWWA Bookshop,fax (02) 9413 1047 This excellent series of booklets e n capsulates the key findings of the first five years of coope rative research in catchment hydrology. T he booklets are presented in an easily readable format, profusely illustrated and targeted at managers and others in the water industry and community groups who are not particularly interested in the fine details of the projects but only the broad scan of results. In the reviewer's opinion they are masterly examples of the editing of complex subj ects into clear and readable technology transfer.

Controlling Sediment Movement and Nutrient Movement Within Catchments Australia's rivers and streams are being degraded, and the water quality derived from most of our catchments is showing the results. Riparian vegetati on is o n e method of controlling sediment runoff. This project focused on the Tarago catchm ent in Gippsland, Victoria. By a combination of sediment tracing and water quality monitoring it has compared various techniques for controlling sediment and associated nutrie nt transfer to the stream and reservoir. The project also quantified the effects on land and timber resou rces of establishing buffe r zones and extended the research into the impacts of wildfire. Finally, the review lists the direction of fu t ure research in thi s field.

Development of An Improved ~eal-time Flood Forecasting Model Floods continue to cause con siderable economic and social disruption, despite massive expenditure on structural wo rks, such as levees. More recent strategies have focused on nonstructural measures suc h as flood warnings, enabling rapid response from affected communities. CRC for Catchment H ydrology research has shown that current simple models of river levels/flows perform quite well, provided they are combined with soil moisture components and information collected during floods. R eal- time modelling, with corrections, to a large extent still d epend on forecaster experience fo r the particular river system. Some form of objective updating is preferred, and this project systematically evaluated many current and overseas models, such as the UK

(PDM) and the USA (HPS), applied to Au stralian conditions. However, results coming from models currently m use in Australia compared favourably. The adaptive unitgraph is considered to be a useful technique. The CRC project provides a benchmark of what can be achieved, to guide the industry in the future.

Urban Stormwater Pollution T his report summarises in a succinct and readable form all the parameters of the pollution of streams and drains that resu lts from urbanisation, with the consequent redu ction of pervious surfaces and increases in inputs. Typical ranges of suspended solids, nitrogen, phospho ru s, COD, heavy metals and hydrocarbons are given and compared with similar ranges for pristine and agricultural catchments. There is a clear explanation of the connection between rain and pollutant loads, with the arrival of first flus h peaks being different for diffe rent pollutants. The fate of each class of pollutants, including gross pollutants (litter etc) is dramatically illustrated, with the effects of storage basins and wetlands analysed. T he boo klet concludes with advice o n techniques for estimating urban runoff and pollutant loads and predictions of the effects of new developments, including examples of the accuracy of the model developed at Melbourne Unive rsity. The booklet ends with thi s unequivocal statement: 'There is no substitute for measured data. Computer models are simply tools.. .'

Stormwater Gross Pollutants Gross pollutants can range from car bodies through plastic litter to plant debris. Despite the visual impact of plastic, the study demonstrated that in an urban catchment the major volume load was vegetation, but that did not contribu te the major part of the nutrient load. The o the r constitu ents are also

classified. Litter was 50% paper products by mass, and 20% of litter and 10% of vegetation usually floats. The project evaluated the effect of storms. Four techniques for trapping gross pollutants were evaluated: the continuou s deflective separation (CDS) trap, side entry pit traps, gross pollutant traps (basins upstream of a weir) and floating deb ris traps on major streams. Some more recently developed traps are being studied. The CDS trap is 100% effective, but is relatively expensive to install, though cheaper to empty than the side entry pit traps. Stormwater managers must select the most appropriate for their circumstances.

Predicting Water Yield from Mountain Ash Forest Catchments This is the longest of the industry reports, and is aimed at the longest time-scale. As an example, one of the aims of the projetcs was to predict the long- term effect of a major bushfire on the runoff from an established forest. The exp erimental work was performed in the protected fores ts of the M aroondah catchment of Melbourne Water, where two areas of fo rest have been closely monitored since 1972, one preserved as regrowth from the 1939 fi res, the other clear-felled and allowed to regrow naturally. The teams have used both sophis ticated and labour-intensive techniques to derive values for Leaf Area Index, transpiration by the trees and the understorey vegetation and evaporation from soil/ litter , and the rainfall inte r~eptio n. Further work estimated the saturated hydraulic conductivity of typical soil profiles (including the macro- pores created by root and worm channels). The data was then fed into two models: T OPOG is a small-scale catchment model which predictes soil moisture, transpiration, rainfall and ru noff as well as the growth of the vegetation. It predicted the runoff from the experimental regrowth catchment with an overall accuracy of +6%. MACAQUE is a model aimed at w hole catchments, e.g. 200-300 km 2 , and preliminary results show that it is able to predict both short- and long- term results of disturbance, such as wildfire, or even logging coupes. As with the other reports, the booklet is clear and con cise, and supremely logical. EA (Bob) Swititot1 WATER SEPTEMBER/ OCTOBER 1998

25


WASTEWATER

RECOVERABLE RESOURCES E A (Bob) Swinton Non-potable reuse, potable reuse (indirect, planned indirect, direct), biosolids, legal liabilities, public health, SAR- these were just some of the key words bandied around at the very successful joint Victorian AWWA/ Insti tute of Water Administration conference held in the rural surroundings of Moama, New South Wales j ust across the mighty Murray from Echuca. More than 150 people registered their interest and were impressed by the wide range of speakers who came from North Carolina, California, Queensland, the Hunter Valley, Sydney and Adelaide to join the considerable local talent from both Associations. The sharpest discussion related to reuse of reclaimed sewage . . . sorry 'wastewater. ' Professor Dan O kun of the School of Public H ealth, University of North Carolina, was full bottle on the many options for non- potable reuse in the urban scene w hich he considered should be developed before the strict requirements for potable reuse need be attacked. On the othe r hand, Ia n Law of C H2M HILL in Sydney was adaman t that we should not fool ourselves-the future lies with indirect, even direct, potable reuse. Based on h ard economic assessment, Melbourne Water has come

fo r reuse was injection into the mains supplying the city. The trouble was that the well-to-do people lived in suburbs high above the city and the people w ho would drink the water would become a separate socio- economic class. Matters m ust have developed furt her since my visit, but su ch legal liabili ties rn.ust weigh heavily in the minds of any authority contemplating direct reuse. Of course, since that visit two major advances have occurred in technology. Membrane filtration was known twenty years ago. Since then advances have come from developm ent of reliability coupled with decreased capi tal and operating costs-a triumph fo r p hysical methods! The other frontier of advance is in biology. BN R technology in the secondary treatment stage has advanced so m uch that ammonia and phosphorus can be removed relatively cheaply, to the stage where eu trophication of a reservoir can be minimised, w hich is a significant advantage. Unplanned indirect potable reuse has long been practised in the more heavily populated countries o f Europe and North America, where the ' magic mile' of a river absolves the wastewater treatment authority from direct legal respon sibility fo r wate r supply to towns downstream. In Australia, where the number of rivers w hich ' ... we should not fool ourselves-the provide such future lies with indirect, even direct, sequential u se is rather limited, -Ian Law, CH2M HILL re- pumping to potable reuse.' the supply to the conclusion that this may well take reservoir is virtually the only option for place within 30 years o r so, and Sydney 'planned indirect potable reuse,' so that Water also foresees such a development not only health aspec ts bu t storage in the Hawkesbury/ Nepean catchment, aspects will dominate the treatment though not fo r the coastal plants. The specifications. Melbourne Water's approach was theme was developed further by Dale Rohe who ou tlined the pilot plants, outlined by Margot Kozicki. The followed by demonstration plants, Western T reatment Plant is the longwhich are being operated in San Diego established 'Werribee Farm' where a combination of lagoon treatment, grass County. But where do the lawyers come in? It fi ltration and reuse by irrigation of is the writer's memory that, after visit- pasture treats about 500 ML/d of the ing the potable reuse demonstration city's western sewage, with final plants in D enver some twenty years ago, discharge to Port Phillip Bay. On the eastern side of the city a the major hurdle was public acceptance for direct potable reuse, and the fear of secondary treatment plant treats about class action. Denver had/ has a problem. 360 ML/d, the chlo rina ted efflu ent The reservoirs are hundreds of metres being pumped through a 56 km outfall up in the Rockies; the WWTP is on the pipeline to be di scharged out to Bass flat plain s of the Plat te River; and Strait at the cliff base. Reuse of the economics dictated that the best option treated eflluent has been encouraged by 26

WATER SEPTEMBER/ OCTOBER 1998

Melbourne Water, but currently only 1,400 ML/year, or ab out 1%, is used by customers close to the route of the pipeline. An eilluent management study has been con sidering the e nvironme n tal effects of the current outfall to the ocean. The study is also predicting the effects of extending the outfall and co n sidering possible treatm ent improvements, reduction of inflows (by combinations of demand management, use of greywater, diversion ofp art of the flow to the Western Treatment Plant) and expansion of eilluent reuse . Options considered for e illuent reuse included wetlands, land irrigation, aquifer storage and recovery, industrial use at H astings, non- potable reuse by dual reticulation , preferably in new developments, and finally potable reu se. The potable reuse proposal envisages a pipeline to deliver the treated eilluent back to the Cardinia R eservoir, to be mixed about 1:4 with fres h water entering from the Thompson, and construction of a further treatment plant for the water to be supplied to the city. The high cost of this scheme would be offset by not having to augment other water resources, which would have to come from the other side of the D ivide. The only conven tional options with any real potential for reducing the volume discharged to sea are demand management (5-10%), land irrigation (8-10% ) and aquifer recharge (10- 20% ), at costs ranging fro m 0.2-0.8 $M per Ml/d. li.owever, potable reuse would guarantee almost total reuse of efflu ent. Its cost i s estimated at $450-500 M, i.e. 1. 3 $M per ML/d, virtually the same as for nonpotable reuse, w hich would only have the potential to reuse some 15-20% of the water. H owever, a long-term change in public attitudes would be needed, and this necessity is being addressed by Sydney Water, with their demonstration 'Water Factory' to be operated long- term at one of its STPs. Nonetheless, our immediate target in Australia is safe and efficient reuse of reclaimed wastewater for non- potable purposes, and this was dealt with by a number of papers. Even here the legal responsibilities are complex. One clear m essage was, Don't give it away. R ather, tie the user into a contract that is flexible enough to cope with normal


WASTEWATER eventualities, and try to spread the load over m ore than on e user in case the user goes out of business. A paper by Andrew Sh erman of Russell Kennedy, Solicitors ou tlined the development of a standard fo rm, Agreement for Sale of R ecycled Water. The legal research for this was sponsored by Goulburn Valley Water, and part-financed by Land Care Australia. The standard form is available for other authorities to use or modify to suit their individual circumstances. The matter has been made a little complex by the guidelines promulgated by the Victorian Environment Protection Authority in 1996 aimed at encouraging the reuse of su ch water. With the flexible approach embodied in these guidelines, described by Maree Bethel, the previous list of hard parameters for water quality set in 1985 by the H ealth D epartment has been replaced by best practice environmental management guidelin es w hich se t objectives and ben chmarks. The legal profession finds this difficult to manage and has already made submissions to the EPA, which is currently considering revisions to the guidelines. D espite advances in technology of treatment, particularly the stipulation of multiple barriers , there will always be a risk, however negligible. A pape r by Nick O 'Connor of AWT applied statistical m ethod s to mic robi ological concepts to try to determine a quantitative microbial risk assessment parameter. B asing his study o n rotavirus, currently the most prevalent cause of gastro-e nteritis 111 children , he combined available data o n hazard identification , dose- response, exposure assessment and risk characterisation to de termine a hypothetical limit for th e co ncentra tio n of rotavirus in treated water. T hough hypothe tical, since hard data are not available, it dem on strated that with current technology the risk of infection was 50% for one person in thousand. Nick stressed that although th e figures are hypothetical, th e technique should be applicable to the wider problem . Another paper by a team from CMPS&F is published 111 the Proceedings, but unfortunately was not prese n ted at the confere nce. This applied the same techniques of risk assessment to the projected upgrade of the Raymond Terrace WWTP in New South Wales to determine w he the r the effluent being discharged to the Hunter River required 99.99% virus inactivation instead of 99% .in order to protect oyster farms 20 km downstream. The conclusion was that it would make no significant difference. Though this was not a paper about reuse, the technique

of quantitative risk assessme n t 1s genenc. A paper by Carl Stivers of Parametrix Australia screened the risks relating to chemical constituents in was tewa ter derived from the proposed tertiary plant at Cronulla, which will recycle most of its output to industrial cooling towers. These risks are not to humans, but to industrial plant and acquatic animals in the fi nal, more concentrated, discharge to the ocean. The legal liability environment was not specifically dealt with for recycled water, but a presentation by Stephen Davis and Adrienne Roche of M allesons Stephen Jaques sp elt out the scenario for the whole range of recoverable resources-water, biosolids, compost etc. They outlined the variou s types of legal risk- inj ury , negligence, contract, legal standards, p roduct liability-and recommended the following 'ten comm andments' as a format for managing such legal exposure: • commitment at Board level • risk identification and assessment • legal requirements • industry standards • compliance system • delegation • training • internal review and reporting • risk transfer • external review. Shifting the emphasis from recycled w ater to include sludge ... sorry , ' biosolids,' a number of papers examined the economics of reuse. Pe ter Griffiths analysed the whole wastewater treatment scen e in terms of the efficie ncy of modern BNR processes and concluded that although the wate r produced was of high quality, the most economic use in most inland situations was not irrigati on but enhancement of natu ral stream flow, since the re is now almost zero pote ntial for algal growth. With regard to biosolids, he concluded that the beneficial use of sludge will be driven by regu lation, not by its direct economic return. The community will be prepared to pay rathe r than dump high nutrient sludge in landfills. Tony Kanak of AW T review ed the record of biosolids use over the past ten years and extrapolated for the next ten years. Since 1989 w h en community pressure in Sydney caught both Sydney W ate r and the regulators 'flatfooted' a tremendous amount of work has been done . Tony fore shadowed t hat any authority w hich is still relying on drying beds, storage and dumping may have to upgrade under the influence of community pressure. Also , as the regulators demand ever-increasing quality in effluents, so does the volume and nutrient content of th e 'residuals' increase.

'Biosolids' do have value, and the term is now entered as su ch in the last edition of Websters Dictionary (U SA), but to use that value depends on a strong com mitment, because it isn 't easy. T ony discu ssed the role of contractors, splitting of responsibility and own ership of on- site facili ties, and listed t he option s already being employed in vario us plants, ranging from blending to fo rn1 soils, composting, both low- tech and high-tech, up to the high-tech Ene rsludge plan t in Subiaco . The W est ern Australian W ater Authority has entered a 2 0- year commitment in order to avoid legal complica tions 111 the future.T ony finished by saying that every wastewater treatment plant w ith diminishing buffer zones sho uld look ahead. Vermiculture is a fairly new tecl11101:.. ogy which is being applied in a couple of wast ewate r treatment plant in Australia, and John Sabine of Vermicultu re resources gave a hard sell on its advantages. The conference included a number of case studies, from the multi-million dollar BOOT project for the Virginia pipeline to reuse B olivar effl ue nt for large- scale horticulture, thro ugh the economic/ecological assessments conduc ted by both Syd ney Wate r and M elbo urne W ater m entioned above, three case studies conducted by Hunter Water, emphasising the value of consultation , down to smalle r scale projects in three Victorian country authorities. J ohn Graham of Barwon Water w as typically direct, asserti ng that effective water reu se will only come about when the price of new wa ter approaches its true co st (ca. $ 1. 20/ KL) so that reclaimed water can be sold. Barwon W ater regards it as a commercial resource, not a was te produ<.ct and is hard-no sed about development. The cu stom e r must d etermine suitabili ty (B arwon Water will not advise on this because of liability, but it does guarantee a certain quality). T he cu stomer designs and pays for infrastructure and operation. However, the price negotiated by Barwon W ater takes into account such inves tm ent. One large scheme is already in operation on this basis. In J ohn's opinion , public acceptance of all reuse schem es is c ri tical, and education should be led by the water industry, which is in for the long haul, and not rely on governments, which have an outlook limited by the n ext election. Edited versions of some ofthe papers are published in this issue ofWater. T he Proceedings ($75) are available from AWWA's Victorian Branc h . WATER SEPTEMBER/OCTO BER 1998

27


m

WASTEWATER

SYDNEY WATER FACTORY

. water sources • treatment sidestreams are produced which can present disposal problems • the processes can be ene rgyintensive • acceptance by the public is low • acceptance by health regulators is yet to be gained.

Treatment Costs

P Longfield Abstract Analysis carried out for Sydney Water Corporation's wastewater strategic planning concludes that for eilluent reuse to play a major role in achieving the Corporation's objectives, potable eilluent reuse will be needed. This paper summarises the analysis that determined the need to pursue potable reuse and co nclu des that potable reuse could become economically viable if the costs of achieving potable levels of eilluent quality can be offset by other drivers such as improving river water quality and deferring water supply augme n tation through dam construction. A specific case study shows that the sewage treatment plants in the Hawkesbury Nepean River catc hment provide a 'zone o f first opportunity' for implementing potable reuse. In addition to high costs, the other major barrier to potable reuse is approval by the regulators and acceptance by customers. This paper explains why Sydney Water proposes to build a water reuse demonstration plant that aims to show regulators, elected officials and customers that the treatment processes are reliable and prove that the Corporation can consistently achieve a safe, high quality product.

Key Words Eilluent reuse, demonstration plant, p otable reuse, Sydney Water Factory

Introduction In accordance w ith a corporatisation comm.itment to prevent all dry weather discharges of sewage to waterways, Sydney Water is committed to reusing treated wastewater. Development of reuse strategies has shi fted Sydney Water's foc us to a total water cycle approach that promotes ecological sustainability by: 28

WATER SEPTEMBER/OCTOBER 1998

• reducing the demand for water from existing water storages • reducing treated wastewater releases to ocean and rivers • managing treated wastewater as a resource instead of a waste. Not all the water used in Sydney needs to be o f the same standard. Eilluent reuse is therefore about matching the water product to a particular application or market. Markets for eilluent reuse incl ude non-potable, direct and indirect potable reuse applications. Currently Sydney Water supplies about 2 per cent of its daily demand for water through non-potable reuse. Investigation of markets for no npotable reuse estimate the future potential for non-potable reuse at between 125 and 200 million litres a day, or around 14 per cent of Sydney's daily water supply. Potable reuse will need to occur if Sydney Water is to move sign.ificantly towards zero discharge of wastewater. This paper discusses the cost issues and community acceptance of potabl e reuse, the timing of its possible introduction and the strategy to gain community and regulatory acceptance.

Potable Reuse Potable reuse uses highly treated wastewater for drinking, eithe r indirectly, after mixing with o ther potable water sources, or d.irectly into a water supply system. It is possible to treat wastewater so that it is suitable for potable consumption with existing technologies such as distillation, dialysis or reverse osmosis. While the technology has existed for many years, p racti cal application of potable reuse has been limited to a few installations p rimarily because: • it requires highly technical processes that are costly to build and operate w hen compared with other potable

The cost of potable reuse is mainly driven by treatment requirements and transport distances. Figure 1 shows the projected additional unit cost of p roducing potable quality water from eilluents that have received different levels of treatment, at an assumed production rate of 50 megalitres per day (ML/d). Potable reuse water produced from tertiary quality eilluent can be less than half the cost of reclamation from p rimary efflu ent (Sydney Water R eport, August 1994). Significantly lower production and transport costs create a zone of first opportunity for potable reuse from the larger inland sewage treatment plants (STPs). · Costs can also be influe nced by economies of scale. Investigations have shown the total treatment unit cost to produ ce potable reuse water at a 50 ML/d plant is approximately half the cost of producing the same quality product from a 5 ML/d treatment plant.

Transport Costs The cost of tran sporting recycled eilluent to users is highly case-specific and depends o n proximity to the point of production and the total nu mber of users. In general, cost of transport is the key facto r limiting the economic viability of non-potable reuse. T his is particularly tru e with schemes to provide non-potable eilluent via duat reticulation schemes in built-up areas. However, potable eilluent reuse offers the potential to minimise costs by distributing the reuse water via existing water distribution networks. Sydney Water's studi es concluded that a zone of first opportunity exists for potable reuse from the larger inland STPs. Inland treatment plants, representing 18 per cent of Sydney's total daily flow, offer higher levels of treatm ent and economies of scale to reduce production costs. At the same time, their location can reduce transportation costs to the existing water distribution networks. Conversely, potable reuse from the Corpo ration's major coastal STPs, representing up to 70 per cen t of Sydney's total daily flow, will generally become the 'zone of last opportuni ty' due to t he additional treatment


WASTEWATER 'Zone of last oppoflunily'

1.4

Major Coastal Sewage Treatment

Plants - 70"4 of Sydney's now

1.2

Slkl 0.50 , - - - - - - - - - - - - - - - ~

'Zone of first opportunity'

Inland Sewage Treatment Plants - 18% of Sydney's flow

0.8

0.40

r--=--===:;::::=========i

via Warragamba

_._ Marginal Cosl Potable Reuse via Prospect

Potable

Reuse

0.2

Cost

Potable Reuse

- - - Marginal Cost r-bn¡Potable Feuse

0.6

0.4

~ Marginal

2016

2021

a+----------~~ Raw Sewage

Primary

Secondary

Tertiary

Advanced

Effluent Treatment Level

Figure 1 Projected unit costs of producing pot able water from various effluent qualities (50 ML/ d)

Figure 2 Marginal unit costs of reuse options for South Creek sewage treatment plants

required and higher transportation costs.

involving a case study of reuse from Potable reuse, witho u t loss of three of Sydney Water's treatment identity, becomes viable within the plants that offered the best opportunity planning period. Offsetting Effluent Reuse to combine these benefits. This case study showed that w hen Costs These plants, all on the South Creek environmental and water augmen tation The need to treat wastewater to very tribu tary to the Hawkesbury-Nepean benefits are considered together, efiluhigh levels for environmental discharge River, have very high levels of treat- ent reuse can be a cost-competitive purposes can help to offset the costs of ment to remove phosphorus for alternative. potable reuse. Studies completed on environmental reasons, plant capacities treatment options for inland STPs, large enough to achieve economies of Public Acceptance Although it appears t hat potable particularly those in the environ men- scale and close proximity to the existing tally sensitive H awkesbury-Nepean wa ter trea t ment and d istribu tion eftl uent reu se coul d become costcompetitive with a new dam withjn 25 catchment, indicated there was still a network. When the reuse water from these years, the scenario of reusing effluent prernium to be paid to achieve signififacilities is distributed via Prospect via Prospect R eservoi r is not automatican t levels of reuse. Potable reuse costs can also be offset Reservoir the combined impact of these cally acceptable to health regulators and by the ability of the reuse water to attributes is that potable reuse from customers. Public acceptance is one of augment water supplies. A major advan- these plants will be relatively low in cost the most significa nt obstacles to impletage of supply augmentation through to produce and transport. Prospect menting potable reuse . reuse is the opportunity to increase R eservoi r is close to the South Creek Sydney Water's Survey of Comsupply through a series of small, 'just in STPs and is the site of the Prospect munity Views on Water Reuse Qune time' steps, thereby delaying the cost Water Filtration Plant, which serves 1996) confirmed the public's percepand e nvironmental consequences of nearly 80 per cent of the Corporation's tion of water as a precious and fi nite water customers. major raw water supply augmentation. resource to be valued and conserved. Distribution via Warragamba Dam Almost 100% of respondents approved When Sydney Water investigated th e role reuse could have in deferring the was included in the analysis to examin e o f non- potable reuse. H owever, next planned augmentation of the the effects of providing 'loss of 'Public acceptance is one of the_ most Co rporation's raw water supplies, it additional found chat the curren tly remote identi ty' to the recycled significant obstacles to implementing augmentation date of 2030 made reuse wa te r. For comparison eco nomi call y non- viable (Sydney p urposes, options for potable reuse.' Water issues paper, September 1994). non -potable reuse from The timing of supply augm entation the same inland STPs were also approval fell to less than 30 per cent for depends on many assumptions includ- included against the marginal capacity potable reuse. ing the effects of demand management cost of developing a new dam on the The general public remains sceptical initiatives and environmental ÂŁlow Shoalhaven catchment. The results of of potable reuse. To overcome this requirements. T he economic evalua- this comparison are shown in Figure 2. Sydney Water is building a demonstratio n proved to be very sensitive to Reuse via Warragamba Dam remains tion 'Water Factory' that will treat a movements of the augmentation date. more costly than a new dam because of portion of the flow from one of the The studi es showed that whe n the pumpi ng costs associated with South Creek plants to potable environmental and water augmentation lifting the reclaimed water to the reser- standards. benefits are considered in isolation it is voir. However, potable reuse via T he Water Factory will have the difficult for reuse to be economically Prospect Rese rvoir becomes cost- ability to treat eith er secondary o r feasible. competitive with a new dam by approx- tertiary efiluent to potable standards. imately 2020 because most of t he The quality of the water produced and Case Study transport costs can be avoided. the operations of the fac tory will be Interesti ngly, when non- potable fully monitored and tested. Results will Reuse may become cost-competitive in cases w here it can be used to both reuse was examined in thi s case study be available to the New South Wales augment Sydney's water supplies and the significant transport costs rendered Health Department, the Environment protect sensitive receiving waters. An this form of water recycling non-viable Protection Authority and Sydney economic evaluation was conducted within the planning period. Water's customers. The aim of the plant WATER SEPTEMBER/OCTOBER 1 998

29


WASTEWATER is to demonstrate that a high quality, safe produc t can be consistently produced. It is expected that the plant will be run for several years in order to build customer confidence and acceptance.

Conclusions Effluent reuse has the potential to benefit both the environmental protection and water conservation objectives of Sydney Water Corpo ration . The po te n tial for no n-potable reuse is, however, limited by the effectively free alternative riparian supplies, a scatte red customer base and relatively high delivery costs. T herefore, the role of nonpotable reuse will not, in itself, enable Sydney Water to achieve its long- term objective of zero discharge during dry weather. In the long term , in greater Sydney, potable reuse is needed if significant etiluent quantities are to be reused. T he cost of trea ting efflue nt to potable sta n dard s may be justified by t he requi rement to achieve very h igh effluent qualities at inland sewage trea tment plants and to achieve reductions in pe r capita extraction from the Corporatio n's water storages. In the case of the South Creek ST Ps, potable reuse could be eco no mi calJy feasible in approxi-

NEW

mately 25 years because of the high levels of treatmen t needed at these plants and their proximity to existing water treatment and distribution infrastructure. The general public and health regulators will be able to review the safety of potable reuse, as well as the environmental and economic benefits of th is application, through long-term operation of Sydney Wate r's reuse demonstration plant.

References Interim R eport (1994) Potable Re-use of Efiluent in Hawkesbury-Nepean Catchment, Sydney W ater Corporation. Issues Paper (1994) Strategic Water Supply Planning, Sydney Water Corporation. Survey (1996) Community Views on Water R e-use, Sydney Water Corporation .

Author Phil Longfield is a civil engin eer with a Master of Engineering Science fro m the University of N ew South Wales and th e Project Director for the Water Factory project. H e has worked in investigatio n and constructio n with Sydney Water since 1978 and was in the C lean Waterways U ni t, a strategic plan ning group wh ich ran the wastewater strategy inquiry.

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30

WATER SEPTEMBER/OCTOBER 19 98


m

WASTEWATER

.

Abstract

Introduction

Effluent Management Study

In November 1996 Melbourne Water engaged the CSIRO Project Office to conduct an effluent management study examining the environmental impact and assessing alternative options to the current practice of discharging chlorinated secondary effluent from the Eastern Treatment Plant to Bass Strait at Boags Rocks. Options being considered are enhancing the treatment process, modifying the o u tfall to increase dilution and reducing the volume of efflu ent discharged. Potable domestic reuse appears to be the most sign ifica nt option for volume reduction. Land irrigation and demand management are also worth considering. This paper presents a summary of the collaborative report, Eastern Treatment Plant: E[f]uent Flow R edu ction (Re- use) Study, prepared by CSIRO Land and Water and Gutteridge Haskins & Davey (GHD ).

M elbourne Water's Eastern Treatment Plant treats 40 per cent of M elbourne's sewage, mainly from domestic sources. The plant produces chlorinated secondary effluent which is discharged via ocean outfall to Bass Strait at Boags Rocks under Victorian Environment Protec tion Au t hority (EPA) licence conditions. An effluent management study conducted fo r Melbourne Water by CSIRO is examining th e environmental impacts of the outfall and assessing options for improvement. The study involves extensive consultation with environment and community groups, State and local government and the general public. Three broad options being investigated and costed are enhancing the treatment process, modifying the outfall to increase dilu tion and reducing the volume of effluent discharged. The main options for eilluen t reduction include demand management and various eilluent reuse schemes. Consultation has encountered a high level of community support for effluent reuse as an essential part of efficient water resource management and in the long term, potable reuse may be a possibility.

The water industry is increasingly looking fo r innovative approaches that will enable it to operate commercially, meet future environmental standards and satisfy the expectations of customers, stakeholders and the broader community. Increasingly, this means not only meeting the current standards proscribed by regulators, but also anticipating stakeholde r and colfimu nity expectations. A high level of scientific expertise and engineering ingenuity combined with community consultation is required to develop long-term strategies that take into account a complex array of environmental, social , heal th and economic factors. In November 1996, Melbou rne Water engaged CSIRO Project Office as a principal consultant to carry out an eilluent management study (EMS) for Eastern Treatment Plant. T he EMS is a comprehensive research project irumlving a number of sp ecialised consultants . The aim of the study, which is required by the plant's Victorian EPA licence, is to 'undertake and complete an investigation and consultation program to evaluate treatment, reuse and outfall extension options to improve environmental performance.'

Key Words Aquifer, community consul tation, demand management, d etentio n storage, Eastern Treatment Plant, effluent, EPA licence, greywater, guidelines, industrial reuse, infiltration, land irrigation, non-potable reuse, potable reuse, reclaimed water, reuse, wetlands

WATER SEPTEMBER/OCTOBER 1998

3~


WASTEWATER T he proj ect has two major components: technical investigations an d community consultation . The technical investigations comprise an assessment of the environme ntal impacts of the existing ou tfall and an evaluation of the options of efflue nt redu ction, treatment improvement and outfall extension .. Consultation has involved a high level of interaction with environment and community groups and regularly updating stakeholders and th e general commu nity o n the study's progress through newsletters, m edia releases and a touring display. The environmen tal research and engi neering investigations were completed in Ju ne 1998. R esults are now being evaluated and will provide the b asis for developing a long- term strategy for effluent m anagem ent. A consultation program is still in progress. Melbourne Water is required to submit a waste management strategy to th e EPA by the end of D ecember 1998.

Eastern Treatment Plant T h e Eastern Trea tment Plan t is owned and ope rated by M elbourne W ater. Located on 1,000 ha at Carrum and comm.issioned in 1975 , the plant n ow serves around 1.2 million custom ers of South Eas t W ater and Yarra Valley W ater, two of M elbourne's three retail water com panies. It treats arou nd 40 per cent of M elbourne's sewage-an average of 360 ML/day. More t han 90% is from d o mes tic sources . Efflu ent from the plant i s pu mped 56 km via the South Eastern Outfall pipeli ne and is di scharged at Boags Rocks on Bass Strait. The plant is a conve ntio nal activated sludge treatm ent plant incorporating influent pumping and screen ing, preaeration and grit re moval, p rim ary sedime ntation, aeration , seconda ry sedime n tat ion , c h lori nati on , ou t fa ll pum ping and screening, sludge thickening and diges tion . The current treat-

ment process produces a high quality secon da ry efflu en t co n si stent w ith current EPA licence conditions.

Effluent reduction opt ions

CSIR O Land & Water and GH D were engaged to investigate and report on effluent flow reduction opportunities for Eastern T reatment Plant. The scope of the investigatio ns included ide ntification and evaluation of options fo r volume reductio n up stream o r 'influe nt flow' and downstream or 'efflue nt flow' of the plant. GHD was respon sible for identifying and assessing feasible options based on the pote ntial total reductio n in efflue n t volu mes com pared with the co st of the scheme. CSIRO Land and W ater further evaluated the opportunities by weighting the economic, public health and environmental impacts and benefits associated with each option. Effluen t discharge reduction opportunities in the short term (within five years) and long term (within 20 years) were examined along with any potential li mitations . T he study made use of a range of data including Geographical Information System data for landuse plans, Australian Bureau of Statistics data for cen sus enumeratio n districts, water industry p ricj ng policy, and interviews with stakeholders and national and local environmental group s. The research incorporated reviews ofl egislative trends affecting effluent volume reduction opportu ni ties and curren t and fu ture infras tructure planning and development optio ns. T hese options, summari sed in Table 2, were separated into two group s: infl uent reduction (reducing th e flow to Easte rn T reatment Plant, with a subsequent reduction in effl uent flow) and efflu ent reductio n (red ucing the volu me of effluent di scharged to Bass Strait). The options will be fu rther evaluated in con sultation with environm ent, commu nity and government groups as part of the regwar EMS consultation process. Based on research , engineering investigations and feedback obtained from th e consul tation program, Melbourne Water will develop a waste m anagem e n t strategy for Easte rn Treatment P lant. The strate gy w ill assess th e cost and benefits of reu se, t reatm e nt process e nhan ce me n t and outfall extension options and recommend the preferred option(s) for implementation. The strategy is required to be submitted to the EPA by the end of D ecember 1998.

Effluent Reuse Eastern Treatment Plan t currently supplies effluent to 30 customers w_ho use reclaimed water for a range of activities including horticulture, agriculture, open space irrigation and grape growing. These reuse sch emes use a total of 1,400 ML of effluent per year (som e 1% of the total) and are limited to properties that lease land at the plant or that are situated close to the South East Outfall pipeline. The quality of effluent supplied to the reuse customers m ust comply w ith the EPA's Guidelines for W astewater R euse. Eastern T reatment Plant effl uent is classified as C lass C under the guid elines (B O D <20 m g/L, E. coli <1,000 org/100 mL).

Consultation Consu ltatio n includes regular m eetings wi th peak env ironmental group s, surfrider groups, a local consultative committee and local and State govern ments. A regular newsletter has kept interested individuals and organisations informed of the study's progress. The gene ral public has b een m ade aware o f the study through regular m edia releases and a touring display. It became apparen t ea rly in the consultation process that th ere is a high level of inte rest in efflu ent reu se . Alt hough t he study was examining reuse as a way oflessening e nvironme ntal impacts from the outfall to B ass Strait, effluent reuse is widely viewed as part of best practice manageme nt of water resources. Expansion of effl uent reuse was no t o nly advocated by environmen tal groups consulted as part of the study but was a commo n inte rest of other group s like surfriders and the general commu nity.

Table 1 Typical quality of effluent su pplied to reuse customers Parameter

Unit

Median

90th percentile 22 4

E.coli

org/100 ml

15

B0 D5

mg/L

14

24

CBOD5

mg/L

8

16

ÂľS/ cm

9 56

1,229

Electrical conductivity

Table 2 Options for reducing the discharge Reference Influent reduction options

Reference

Methodology

1-1

Diversion to Western Treatment Plant

E-1

Wet lands

Influent Reduction Options

1-2

Detention storage and local reuse

E-2

Land irrigation

1-3A

Demand management

E-3

Aquifer storage and recovery

Option 1-1: Diversion to Western Treatment Plant M elbourne's sewerage

1-3B

Greywater reuse

E-4

Cooling water

l-3C

Infiltration/ inflow red uction

E-5

Non-pota ble reuse

E-6

Pota ble reuse

32

WATER SEPTEM BER/ OCTOBER 19 98

system is comprised of two integrated sys tems w hic h transfer flows to Easte rn Treatme nt Plant in C arrum and W es tern Trea tment Plan t n ear


WASTEWATER would lead to a total annual flow reduction ofless than 0.2%. Option l-3A: Demand management

The South Eastern Outfall discharges at Boags Rocks on the Mornlngton Peninsula

Werribee. The system has the ability to divert around 10% of the total daily sewage flows to either plant. C urrently these flows are diverted to take full advantage of the lower cost of treatment at Western Treatment Plant during dry weather. Wet weather flows are diverted to Eastern Treatment Plant to maximise the capacity of the transfer system and minimise sewage spills. The efflu ent reduction study evaluated the possibility of capital works to enable increased diversion of flows to Western Treatment Plant to reduce the volume of effluen t discharged to Bass Strait (see Table 3). Major expenditure is required to significantly increase diversion. It is also doubtful whether increasing flows to Western Treatment Plant delivers an overall environmental benefit, as it increases discharges to Port Phillip Bay (a partly enclosed Bay ecosystem) without reducing the total volume of ocean discharge. However, if effluent re u se from the Weste rn Treatment Plant is increased there may be an environmental justification for diverting additional flows to the western system. Due to the high capital cost involved in upgrading the existing sewe rage system this option of reducing inflow to Eastern Treatment Plant is limited and may result in only a 5-10% additional annual flow reduction. Option 1-2: Detention storage and local reuse The primary function of

detention storages is to provide additio nal capacity in extreme wet weather conditions to avoid sewage overflows. D etention storages hold peak wet weather flows diverted from the sewerage system, returning flows to the system w h en capacity becomes available. D etention storages can also be designed to intercept flows from new developments w here there is a lack of capacity in the existing sewerage

system. This approach is often more cost-effective than the traditional approach of augmenting downstream sewers. Where the opportunity exists, detention storages can be fitted with a treatment unit to produce high quality effluent for local reuse. For the purpose of the study, Yarra Valley Water and South East Water staff were interviewed regarding detention storages under construction or investiga ti on. The largest of these is the Bundoora Flow Control Facility, which will provide 20 ML extra storage capacity. This facility is to be constructed to relieve the Darebin Main Sewer and provide extra capacity before connecting a proposed upstream development. The proposed detention storage tank site is located within 5 km of a large area of public land which includes golf courses, parks, w ildlife reserves, hospitals an d the Bundoora Camp u s of Latrobe University. There is the potential for local treatment and reuse on this site, at a capital cost of around S0.5 million. However, this option for flow reduction to Eastern Treatment Plant is limited to 1 ML per day in dry weather (four to five months p er yea r) and

Water conservation has significan t potential to reduce sewage flow to Eastern Treatment Plant and consequently the volume of the effluen t discharged to Bass Strait. Consultation has shown this to be a highly favoured optio n as it provides environmental benefits beyond reducing the impacts of the outfall. There is also increased interest in demand management due to recent pricing reforms w hich en courage water conservation and are likely to increase the adoption of water saving technologies and practices. The reforms include a separate sewage di sposal charge w hich is calculated as a proportion of winter water usage. Table 4 presents potential reductions in water consumption which can be achieved by a typical 'water-efficient' household. It is estimated that approximately 60% of domestic water used is discharged to the sewerage system. There are significant redu ctions in sewage flows which ca n be made through more efficient household water use withou t requiring major capital expenditure. Water conservation practices can be implemented by industrial users also. Like most water authorities, Melbourne Water accepts and treats industrial wastewater with domestic waste. Waste minimisation and the treatment of industrial waste 'at the source' is EPA and water industry policy. The j oint efforts of the EPA and retail water companies should result in a gradual reduction in industrial wastes discha rged to the sewerage system. However, this will have a minimal effect on the reduction of flows to Eastern Treatment Plant as trade waste represents less than 10% of the total flow to the plant. In the long term, domestic water conservation could lead to a 5-10%

Table 3 Dry weather f low diversion options Case

Daily flow ML/ D

Current

1 2 3 4

Flow reduction ML/ D

360 355 347

5 13 42 137

3 18 223

% Reduction

Capital cost $M

1.4 3.6 11.7

7 20 22

38.0

64

Table 4 Potential reduction in household water consumption Typical usage l / capita/ day

Typical reduced usage l / ca pita/ day

Reduced volume

23

Toilet flushing

65 50

50 40

Laundry

40

20 25

Kitchen

15

30 10

Use area Bathroom

%

33

WATER SEPTEMBER/OCTOBER 1998

3~


WASTEWATER ments, Camberwell/Canterbury Basin, Gardiners Creek Main and Kew Pump Station Basin, have been identified as exhibiting excessive infiltration ratios. It was estimated that implem entation of a flow reduction program fo r these three catchments would yield a reduction up to 6% of annual flow to Eastern Treatment Plant. Becau se infiltration occurs throughout the system , the capital costs of addressing it are greater than the costs of system augmentations combined with downstream effiuent reduction m easures.

Discharge Reduction Options

The project has Involved a high level of community Involvement

reduction in total dry weather flows, while reductions in industrial discharges could lead to a reduction of 1- 2% . Option 1-3B: Greywater reuse The term 'greywater' is used to describe the 70% of domestic sewage not discharged through the toilet. For safe reu se, greywater must e ither be treated to remove or destroy pathogens, or human contact with the water m u st be prevented. There is an as yet undefined increase in risk to public health and the environment with the use of greywater. Although legal application of greywater in Au stralia would require amendmen ts to State legislation, model guidelines for domestic greywater use have been prepared (Urban W ater R esearch Association R esea rch R eport N o. 107). Below-ground application of greywa ter is preferred , bu t even that is controversial due to the difficulties in defining the risk and responsibilities between th e owner, the regulator and the general public. Installation and m aintenance costs of commercially available greywater reuse systems are comparable to the cost of sewer reticulation, so this is often a prohibitive factor for indiv idual consu m ers . Co nsultation has shown greywater reuse is an option that is o f inte res t to the environme n tal movement. Household greywater reuse schemes are mainly adopted by individ-

uals with strong environme ntal concerns and are no t likely to be attractive for the general public due to the maintenan ce difficulties. Previous M elbourne Water studies have shown around five per cen t of households already reuse a ce rtain amount of greywater for irrigation, m ainly laundry water. Due to the health, environmental and regulatory difficulties of greywater reuse, the long- te rm reduction in annual flow to Eastern Treatment Plant would be likely to amou nt to less than 1%. Option l-3C: Infiltration reduction

M elbourne Water and the retail water companies have undertaken a compreh ensive program of sewerage system and computer modelling to gain an understanding of the system 's performance and capacity limitations. Sewage spills are becoming unacceptable to the community, w hich is placing increasing value on the aesthetic, environmental and recreational values of waterways. M elbourne Water is progressively addressing capacity problems in its sewerage mains through capital works and increased monito ring. Reducing infiltration of sto rmwater into the sewerage system is al so being pursued in conj unction w ith the retail water companies. This is p arti cularly a problem in older sewerage catchments. T hree of the older northern catch-

Table 5 Proposed wetlands sites Area ha

Wadsley Road

190

Carrum (land owned by Melbou rne Water)

via Eel Race Drain to Kananook Creek and Port Phi lip Bay

Summer Road

130

Baxter (flood area)

Balcombe Creek and Port Philip Bay

Ellerina Road

130

Safety Beach (extension of country club)

Brokil Creek and Port Philip Bay

Browns Road

100

Boneo (part of Tootgarook Wetlands)

Tootgarook Wetlands and Port Philip Bay

34

Location

Drai ns to

Site

WATER SEPTEMBER/ OCTOBER 1998

Option E-1: Wetlands The study investigated a series of remnant or degraded wetlands along Port Phillip Bay stre tching south fro m Easte rn Treatment Plant to the upper reaches of C hinaman s Creek in B oneo. For eco nomic and practi cal reasons the sites investigated are close to Eastern Treatmen t Plant o r near the outfall pipeline. Another essential requirement was for the sites to be close to permanent watercourses to allow drai nage to either Bass Strait or Port Philip Bay. Four potential site¡s have been identified as suitable which have not been zoned for land and infrastruc ture development. The sites are listed in Table 5. The m ain advantages of this option are that wetlands wou ld be reinstated in the areas o f their historic location s, additional wildlife habitat would be created and there would be the possibility of also treating stormwater flows through the w etlands, alleviating the need for effluent distrib utio n to customers. The disadvantages of this option are the limited sites available, relative high capital and maintenance cost and some discharge of effiuent to Port Phillip Bay (although the effi uent wo uld have undergo ne treatment and¡ nutrient removal through the wetlands). H owever, despite the limitations, th e ancillary environ mental benefits make this option worth investigating. An estimated reduction in the efiluent volume based on development of all fo ur sites could provide 2-2.5% reduction in the annual discharge to Bass Strait. Option E-2: Land irrigation Land irrigation is currently the main eflluent reduction program at Eastern Treatment Plant. Irrigation is regulated by State government agencies to protect the environment and public health . A range of soil-water characteristics are critical for the su stainabili ty of irrigation systems. These include such aspects as soil and water salinity hazards, soil permeability, the sodium adsorption ratio of the irrigant and groundwater levels.


WASTEWATER The conditions around Eastern Treatment Plant are not ideal for irrigation using effluent. Irrigation application rates cannot exceed the difference between rainfall and evapotranspiration without the reuse scheme requiring an EPA discharge licence. For the area surrounding Eastern Treatment Plant this difference is about 400 mm/yr. Irrigation is restricted to the summer months. For the purpose of the study conventional and unconventional agricultural opportunities were considered. In conventional agriculture, effluent is better suited to growing crops with high nutrient demand like fibre, cereal, fruit and vegetables. A nu mber o f unconventional agricultural practices such as hydroponics and growing commercial hemp, macrop hytes and woodlots may provide be tter opportunities fo r effluent reuse. More research i s required into species selection, improvement in crop yield and identification of markets for u nconventional agriculture. It was concluded due to the high infrastructure costs that only large- scale agricultural reuse schemes would be cost-effective. The possibility of a fairly large irrigation sch eme has been identified for the vegetable growing areas of C lyde and Dalmore. A three-stage eilluent reuse scheme for existing and proposed horticultural developments in the Cranb!)urne/Narre Warren region was also developed. The principal advantages of t he proposed schemes include the potential for a high reduction in volume, provision of an alternative water supply to suppleme nt limited groundwate r resou rces in the area and staged installation to service potential growth in the region. T he disadvantages assessed were the proximity of a local treatment plant operated by South East Water which w ill also be seeking efflu ent reuse opportunities, the high capital cost of a transfer system and the potential for negative public p erceptio ns affecting the market value of produce. This scheme will be investigated fu rthe r as it allows for a long- term reduction of Eastern Treatme nt Plant's effluent volume of 8-10%.

Project leader Brian Newell (right) with Margo Kozicki briefing local MPs

extends for more than 25 km from Point Nepean to the Selwyn Fault and covers an area of approximately 100 km2. It provides good quality groundwater with high bore yields and is intensively utilised. T he Bridgewater Formation , if recharged with effl uen t and properly managed, would continu e to serve the area in the fo reseeable fu ture. However, a recent study by Sinclair Knight Merz found the quality o f groundwater in the Nepean Peninsula to be under threat from stormwater infiltration, over- fertilisation, p oorly maintained septic tank systems and eilluent reuse. As a result of this study, greater regulation of groundwater bores combined with measures to stop contamination of the aquifer were recommended. The main advantages of the aquifer recharge optio n are the potential to supplement natural groundwater resources to satisfy increasing demand, th e fact that there is no need fo r direct distribution to customers and the creation of a diffused indirect discharge to Bass Strait. The disadvantages of this option are the potential adverse effects on beneficial uses of aquifer resources,

doubtful long-term sustainability and high capital and operating costs. T his option has a potential to reduce the annual volume of efflue nt by 10-20%. H owever, consul tation has found little support the option, as i t is seen to create a de facto groundwater outfall wi th eventual discharge to Bass Strait. Option E-4: Cooling water Industrial reuse opportu nities have been investigated for major industry in the H astings and Dandenong areas. H owever the EPA's waste minimisation policy and water pricing reforms have led to the introduction of waste minimisation and wate r recycling programs in most indus~ries. M aj or users like BHP Steel at Hastings harvest stormwater and recycle internally and will continue to improve their waste management practices. As this industry trend continues, option s fo r effluent reu se will decrease. It was estimated that less then 1% of effluent can be utilised by industrial reuse. Option

E-5:

Non-potable' reuse

Non-potable reuse involves installation of a 'third pipe' syste\n to supply individual properties with effluent for

Table 6 Comparison of options Option

Reduced Estimated ca pital volume % cost range $M

Upper cost Discounted unit cost per volume $ per kl reduced $M

Option E-3: Aquifer storage and recovery P revious investigations have

Detention storage and local reuse

1-12 <0.2

7-64 1.5-2

1 .6 2.5

Demand management

1-12

0.70

Treated greywater reuse

2 5-6 2-2.5

10 2.5 - 60

0.25

considered injecting effl uent into the Koo- Wee-Rup groundwater aquifer which has been depleted by overuse. H owever, su bsequent restri ction o n groundwater pumping in these areas has restored aquifer levels. The EMS has investigated the possibility of recharging the Bridgewater Aquifer Formation o n the Nepean Pe ninsula. The Bridgewater aquife r

2 .5 8.5 2.5

9.86

Diversion to Western Treatment Plant

Infiltration Wetlands Land irrigation Aquifer recharge Industrial reuse Non-pota ble domestic reuse Potable domestic reuse

8-10 10-20 <1.0

20-170 20-25 25- 30 5-10 1.5-2

0.34 0.66

1.93 0.59

0.8

0.2-0.42 0.31 0.16 0.46 0.39

5-6

15-20

0.15 0.5 1.25

95

450- 500

1 .3

WATER SEPTEMBER/OCTOBER 1998

3~


WASTEWATER u se on gardens and for toilet flushing. Tw o non-potable reuse options were investigated: re trofitting of existing developments and installation of 'third pipe' systems in new developments. Previous investigations of retrofitting existing developments have involved installation of distribution mains and reticulation systems in trenches dug as part of a program to ex tend the sewerage systems to outlying unsewered areas on the Southern Mo rnington Peninsula. The schem e w as designed to reuse approximately 2,340 ML of effiuent p er year in an area including R ye and Portsea. An estimated capital cost of the proposal was $32.6 million which envisaged approximately 19,500 properties connected to the sy stem. Since the investigations were completed the backlog program has been significantly slowed down and the opportunity for a large-scale reu se program has b ee n somewhat diminished. Backlog sew erage schem es are curre ntly considered for Flinders, Shoreham, Point Leo , B alnarring/ M erricks and Tyabb. There is an opportunity for 'third pipe' systems in these townships. Servicing new developme nts with third pipe systems was considered for the C ranbourne/Narre Warren area. According to land release forecasts, about 45,000 households will be developed in this area in the near future. The close proximi ty of this development to Eastern Treatment Plant m akes the option of n on- potable re use worth pursuing. It is estimated that fitting all the proposed developments with third pipe system s would result in a total redu ction in efflu e nt di scharged of 8 ,200 ML per year. Howeve r, the viability of these schem es will depend on the developer's willi ngness to meet som e of the capital co sts and the preparedness of individual consumers to pay for the operation of the system. There have been significant difficulties for third pipe system s in new developments interstate. The p erceived advantages of the non-potable reuse option include the potential to involve the community in managing w ater resources and the opportu nity to integrate the system w ith other reuse option s e.g. future potable re use. The disadvantages include high capital and maintenance costs, difficulties in marketing the scheme to developers, lack oflegislation assigning public h ealth and environmental responsibilities (thereby increasing the ri sk to the water authority), the seasonal nature of such schemes and a relatively low volume reduction. This option may in the long term provide 5% of annual effiuent volume. 36

WATER SEPTEMBER/OCTOBER 1998

Option E-6: Potable reuse Indirect potable reu se is widespread in overseas countries mainly wh ere drinking water is extracted from river system s which also receive treated w astewater. There are very few instances of ac tual or demonstration systems of direct p otable reuse. In Australia potable reuse has limited immediate application and is associated with a negative public perception. In spite of this, it is generally accepted that potable reuse provides the best opportunity for significa n t reductions in the discharge of effiuent to the environmen t as well as conserving existing natural water resources. Sydney W ater is building a potable w ater demonstration plant at Q uakers Hill in Sydney to purify effiuent to drinking water quality. Two parallel treatment processes will be used to allow comparison and selection of th e options which b est satisfy public health and economic objectives. Operational and w ater quality data will be collec ted over a number of years and towards th e end of the trial water from the plant will be introduced into Sydney's w ater supply (see Longfield, this issue) . For the purpose of the study, extension of the C ranbourne/Na rre Warren non- potable reuse sch eme to achieve potable domestic reuse was considered . T his would require construction of a 25 km pipeline to tran spo rt Eas tern Treatment Plant's effiuent to Cardinia R eservoir, where it would be shandied with potable water. B efore entering the potable w ater supply system , effi uent would be treated to m eet water quality crite ria for drinki ng w ater. C onstruc tion of a water treatment plant would be required in the vicinity of Cardinia R eservoir. Potable reuse schemes can almost guarantee total reuse of effiuent. The high cost, both capital and operational, can be offset by the savings in not having to augme n t other water resources. It will be twenty years before augm entation of the current water supply is required, making potable reuse a long-term option. As a strategic direction, potable reuse enjoys a high level of support among environmental groups, although there is widespread recognition that a change in public attitudes is required and should be actively pursued by water businesses as part of responsible water resource management. The estimated percentage of possible effiuent volume reduction is a dramatic 95% .

Conclusions From all effiuent redu ction options investigated for Eastern Treatme nt Plant, either upstream or downstream

from the plant, the po table domestic reuse option provides the m ost significant volume reduction opportuni ty. The other significa n t option s worth pursuing are land irrigation and demand managem ent. T he option s have been summarised in Table 6 to allow compari son of possible volume reduction with the associated capital co st of each schem e. It is universally recognised that innovative effiuent management program s depend to a great extent on public acceptance of alternative water sources. This acceptance can only be achieved with a high level of engagem ent with the commu nity and community representatives. M elbourne Water will continue to work with environm ent and community groups and the general public to continue to identify opportunities for effiuent reduction and public education.

Acknowledgements T he findings and recomme ndations of the collaborative report produced by CSIRO Land and W ater and GHD for Melbourne W ater form the basis of this paper. The authors wish to thank Coli n White ofGHD and D r Jay Gomboso of CSIRO Land and Water for their assistance and expert advice during the study.

References Gomboso J , Ritchie VA, Thomas] F, White C , Bo ags R ocks Effiuent Flow Reduction (R euse) Study-R esearch Outline (1998) Gomboso j , Ritchie VA, Thomasj F, White C, Eastern Treatment Plant: E ffiuent Flow R eductio n (R e-use) Study (in prep.) En vironment Protectio n Au thority, E PA Waste Discharge Licence N o. EW 367, Victorian Government: Melbourne. Environment Protection Authority, Guidelines for W astewater Irrigation (1992), Victorian Government: Melbourne. Environment Protection Authority, Guidelines for Wastewater R euse, (1996), Victorian Government: Melbourne. Enviro nment Protection Autho rity, D raft State Environmental P rotection Policy (Groundwaters of Victoria) (1994), Victorian Government: M elbourne.

Authors Malgorzata (Margo) Kozicki is an Environmental Engineer with a M.Env.Eng . from the D epartment of Sanitary Engineering, Technical University of Wroclaw, Poland and is the Proj ect M anage r, Effluent M anagem ent Strategy with Melbourne W ater, Eastern Treatment Plant, PO Box 125, C helsea Vic 3196. Tony Antoniou is a Civil Engineer and M anager of Easte rn Treatm e nt Plant, M elbourne W ater.


ii

ENVIRONMENT

In April this year at the WaterTECH Conference in Brisbane Dr Helen Locher was presented with the inaugural Young Water Scientist of the Year Award for her outstanding PhD research into the effects of long- term mining and power operations on the rivers running into Macquarie Harbour in western Tasmania. Here Helen, a member of the Cooperative Research Centre for Catchment Hydrology, outlines the research project for Water readers. A full paper based on the PhD thesis, Mining Discharges to the King River, Tasmania: Sediment Transport and Storage, is to be submitted to the internationaljournal, Regulated Rivers. Introduction Historically th e King River, w hich h as an 800 km 2 catchment o n the very wet west coast of Tasmania, has been the recipient of mine tailings and slag disc harged fro m th e M ount Lye ll copper mine, located o n the Queen River tributary to the King River (see Figure 1). Between 1916 and 1994 the m.ine discharged 97 million tonnes of tailings, the very fine grai ned waste sedime nts from th e mine's milling process. Additionally, be tween 1929 and 1969 up to 4.5 million tonnes of coarser grained sme lter slag we re di scharged . The mine wastes into the King Rive r represent the largest di rect discharge o f sedimen t fro m human activity to an Australian river. In addition to coping w ith excess sediment loads from the mine w astes, the King River flow is regulated by a 150 MW power stati on located just 1 km upstream of the Queen River con fl uence. T he power schem e commen ced op e:-atio n in early 1992, causing regu lation of the flow , and it operated fo r several years w hile tailings were still being discharged.

M i ne wastes in the King River system prese nt an environmental proble m o f en ormous magnitude, n ot only from the sediments but also from the high copper loads in the runoff from the lease site. T he receiving body of water is Macquarie H arbour, an almost

landlocked harbo ur w ith li ttle tidal fl ushing and a growing aquaculture and tourism industry. The King River sediment study was conducted between 1993 and 1997, the power station having come on line in February 1992 and the mine d osing in D ecember 1994. The a.im of the study was to determine the i nfluence of mi ne waste discharge and flow regulation on sediment transport and storage in the King River. T he obj ectives of the study were to: • develop a sediment budget • determi ne suspended sediment and bed load transp ort rates • detenn ine th e infl uence of power station operations • assess the stabili ty of the sedime nt sto rages.

Sediment Budget

Tailings discharge from Mount Lyell Copper mine, Queenstown

T h e sediment budget was dete rmined using a number of techniques, including ana lysis o f mine records, comparison of survey cross- sections and harbour bathymetry, auguring of King River sedime nt banks, and collection of drill cores in the Ki ng River bed . The WATER SEPTEMBER/ OCTOBER 1998

37


ENVIRONMENT were onJy twice the bed load transport rates, and total sediment transport rates had reduced to less than 10% of the pre-mine closure rate.

Influence of Power Station Operations Of great interest was how sediment transport rates were influenced by power station operations. Pre-mine closure, the turning on of the powe r station caused the su spended sediment concentrations to rise from less than 100 to several thousand mg/L. The spike in suspended sediment concentration was related to dynamics at the confluence of the Queen and King Rivers. While the power station was on line, tailings were restricted from entering the King River. When the power station turned off, tailings freely enter~d the King River but quickly settled out of suspension because of the low flow. When the power station turned on again, a ready supply of settled tailings was lifted into suspension. These spikes were particularly of concern because they caused plumes of tailings, which have historically been linked to fish kills, to be transported o ut into Macquarie Harbour. Since tai lings disc harge ceased , suspended sediment concentrations decreased by several orders of magnitude in the King River to a maximum of 120 mg/L. Spikes in concentration still occur on start- up of the power station, but are from a different source. Before the mi ne closed suspended sediments were from the Queen River, whereas post-mine closure sediments are du e to erosion of the tailings banks in the last 8 km of the river.

Channel Stability

River bank before the mine closed

findings showed that 90% of the tailings discharged reside in the delta, with onJy 4% of the tailings still in the bed and banks of the King River. The small proportion of tailings in the river was a surprising finding given the high visual impact of these tailings banks. Of the smelter slag discharged, 80% is in the river bed and 20% in the delta.

Sediment Transport Rates Su spended sediments were measured primarily using automatic water 38

WATER SEPTEMBER/OCTOBER 1998

samplers, the representability of which was regularly tested by depth-integrated sampling in conjunction with gaugings across the cross- section . Bed load was measured using a H elley-Smith portable sampler which sat on the river bed. On average, suspended sediment rates measured pre-mine closure were SO times the measured bed load transport rates, showing the dominance of tailings being transported in suspension. Six months after mine closure, suspe nded sediment transport rates

Techniques used to assess channel stability were survey cross-sections, monitoring of erosion pins, and photographic monitoring. Pre-mine closure, freshly discharged grey tailings were draped on the face of the sediment banks when the power station turned off and water levels dropped. When the power station turned back on and water levels rose, the grey tailings were remobilised off the face of the banks and transported out into the harbour. Post-mine closure, there are no more freshly discharged grey tailings to coat the sediment banks, and the daily rise and fall in water levels is causing undercutting and collapse of the sediment banks. C hanges in the channel over time are also shown by survey crosssections. Fluctuations in channel depth over time can be related to the sediment supply (mine tailings and slag) and the channel's sediment transport capacity (influenced by regulated flow).


ENVIRONMENT

Highly concentrated suspended sediments immediately downstream of the confluence of the King and Queen Rivers before the mine closure with the power station off-line

Figure 1 Location of the King River

Conclusion T he signi ficance of the findi ngs from this study are multiple. The histo rical and anticipated response of the King River to the external changes is now well understood , as are the sources and causes of environmental impacts in the river system. The study fi ndings have had impli ca ti ons for powe r sta tion

operational guidelines with regard to movement of th e tailings and bank stability. Knowledge of the relative location s and stability of the mine wastes in the system and the most likely future response of the river has been important in the design of remediation strategies for the river system.

Author Dr Helen Locher, a membe r of the Cooperative R esearch C entre for Catchm ent Hydrology, is a Seni or Enviro n mental Consultant with the Hydro-Electric Corporation , Tasmania, heading the aquatic environment program. She gained her MEnvSci and PhD from Monash University.

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ENVIRONMENT

.

DEPENDENCE OF AUSTRALIAN ECOSYSTEMS

ON GROUNDWATER T Hatton, R Evans

A number of Australian ecosystems depend on groundwater and would be detrimentally affected by its extraction for human purposes. A report prepared for the Land and Water R esources R esearch and D evelopment C orporation (LWRRDC) has found that they have an importan ce far in excess of their geographic extent. This edited version of the 120-page report, D ep enden ce of Australian E cosystems on Groundwater, has been prepared by E A (Bob) Swinton. Introduction

T errestrial vegetation may depend to varying degrees on the diffuse discharge T he role which groundwater plays in of shallow grou ndwater, (root uptake) controlling ecosystems in Australia is very poorly u nderstood . With a few eit he r to su stain transpiration and notable exception s, there is virtually no growth through a dry season (e.g. tropiliterature on this very important topic . cal woodlands) or fo r the maintenance As an unseen and poorly understood of pere nnially lush ecosystems in otherresource, groundwater nonetheless wi se arid environments (e.g. streamside fu ndamentally controls the health of vegetation such as river red gums along major ecosystems across Australia. To th e usually dry river beds in the help ensu re the continued health of Australian int erio r). Included are these ecosystems, the Land and Water groundwater-dependent forests and Resources Research and Development woodland s which lac k the surface Corporation (LWRRDC) commis- expressions of water normally associated sio ned th e report, Dependen ce of with wetlands. Tree plantations which A usn·alian Ecosystems on Ground- may extract groundwater are also water, to provide a basis on which to considered . In such cases the vegetatio n identify issues w here fu rther research itself may induce gro undwater discharge to the atmosphere. and investigation are required . Stream hyd rographs may have a The repo rt examines ecosystem component of base fl.ow whose origin is dependence on groundwater fo r all o f groundwater discharge. T his may be mainland Australia, T asma ni a, and near- shore islands and considers estuar- vital to the character and composition of in-stream and near- stream ecosysine and near-sho re marine ecosystems. For the purposes of identifying tems. Base fl.ow is a conceptual quantity ecosystem dependence, grou ndwater is defined as that water in the system Bass River at Loch · Daily flow and Computed which would become less available to Bareflow (from Grayson et al 1996) indigenous plants and animal s if it were 1200 - - streamflow to be developed fo r human use by 1000 - • • • baseflow 'g' p um ping o r alterati on of inpu t o r 800 ..J ~ 600 quality. 3: 0

Ecosystems Considered Four maj o r types of ecosystems are considered with respect to groundwater dependency: terrestrial vegetation, river base flow system s, aquife r and cave ecosystems and wetlands. 40

WATER SEPTEMBER/ OCTOBER 199 8

u:

400

200 0 . . ~

"'

~

~

Fl

Figure 1 Example of base f low derived from stream f low using the Nathan and McMahon (1990) method

resu lti ng from sta ti stical o r grap hic methods of breaking up a stream hydrograph into components of quick and slow responses to rainfall. These are not directly equivalent to the amount of surface and su bsu rface (groundwater discharge) flow. Base flow is made up of several components including groundwater discharge, bank storage and lateral unsaturated flow. H owever, base flow is generally considered to arise to some signifi can t degree from groundwater discha rge to streams. Figure 1 p rese nts credible base flow estimates w hich have been arrived at using a statistical algori thm method. In considering the significance of groundwate r processes influencing ecosystems in rivers, it is postula ted that several key factors dominate. Of significa nce is the volume of base flow and its temporal variability, not the mean annual flow of the river. In local fractured rock systems, grou ndwater development and landuse changes will have highly variable impac ts on base flow volume an d ecosystem dependence. In contrast, in regional porous aqu ife r systems, grou ndwater development and landuse change will be mo re likely to have an effect on base flow and affect dependent ecosystems in a mo re predictable manner. W he re base flow is maintained in areas of relatively low rainfall (e.g. the Broughton River in South Australia) and the base flow is a high proportion of the mean annual flow, a u nit change in


ENVIRONMENT base flow will have a significantly greater impact on ecosystem health than in areas w here rainfall is higher and/or the dry season is shorter. H yp ogean life exists in a contin uum through different types of karstic, cave, porou s and fissured aquifers . Gibert (1996) asserted that this fo rm of life is as dive rsified as i n the su rface bi otic milieu, and that aquifers fo rm the most exte nsive array of freshwater ecosystems on our plane t. T hat these ecosystem s exist in the groundwater makes th e nature of their dependence absolute, albeit poorly un derstood and appreciate d. Only those wetland system s with a know n or likely component of groundwa te r disch arge in their h ydrologi c cycle are considered . These ecosystem s include tidal flat and coastal inshore waters w hose ecosystem s may depend on the flux of groundwater either as direct discharge or through base flow discharge at m ouths of rivers and instream ecosystems themselves. A geomorp hic classification of wetlands provides the physical background , bu t within each o f the classes, diffe rent flo ristic assemblages and their associated fauna! comp onents occur. Therefore, permanent wa ter in a river may support stream side red gum co mmu nities i n southern Australia and caj epu t communities in the Pilbara.

Fauna The significa nce criteria in the report reflect a vegetation -orie nted bias since vegetation health generally underpins the health of an eco system . H owever, some systems have fa unal components w ith a more direc t d ependen ce on groundwater. For instance, terrestrial and avian fauna may rely directly on groundwater as a source of drinking water in th e dry season via seepages, springs etc., or as the direct source of habitat in the case o f aquat ic animals (e.g. crocodiles, turtles, fish , macroinvertebrate s) . Where p ossible, these fa una! depe ndenci es are ide n tifi ed . N on eth eless, the role of groundwater in m aintaining and supporting fa una wh ich are not related to vegetation is very p oorly known and understood. Also of particular impo rtance is the role of groundwat er in supporting Abo riginal communities throu ghout mu ch of C entral Australia.

Groundwater Processes The gen eral processes o f groundwat er rec harge, through-fl ow and disch arge are well understood and m ay be quantified locally. Ecosystems m ay interact with all th ree of these processes. However , w here through-flow system s are near or at the land surface in lakes and rivers, ecosystem s will develop to

exploit this water, probably in a depen- aquatic ecosystems. For example, in dent way. The ecosystems oflakes with West ern Au stralia the re is a large local groun dwater m ounds are not number of ecosystems either already locally dependent on groundwater. degraded by or under threat from rising The magni tu de and variati on in saline watertables and associated saline groundwater processes dep ends on the discharge to streams. seasonality of recharge processes such as In other systems such as the Darlingrainfall and drought and on water use. Barwo n the relative discharge o f C onsequen tly, sites that are normally in groundwater w ith respect to surface a disc harge m o de m ay som etimes flows may be directly proportional to become recharge sites to th e aqu ifer. the ri sk o f algal blooms throu gh a Local processes are th ose involving com plex sequence of chemical, physical recharge and disch arge occurring wi thin and biological reactions. hundreds or thousands of m etres of The rep ort emphasises that ecosyseach o ther. C ause an d effect with tems depend on both the quantity and respect to hydrogeological response are quality of groundwater, as opposed to relatively easy to define. These local vulnerability to increasing groun dwater processes may be strongly infl uenced by discharge. recent climate and landuse patterns and may th erefore exhibit large temporal Criteria for Dependence variability. Ecosystems m ay develop a T h e main criterion adopted to assess m ore opportunistic d epende ncy o n and ran k significa nce in the report is groundwater in these lo cal system s. that the degree o f d ependence o n At the o the r extre me, regional groundwate r i s proportional to the processes operate over areas of up to fraction of the annual w ater budge t thou sands of kilom etres and tend to be which an ecosystem de rives from more temp orally invariant. Ecosystem groundwa ter. dependen ce may the refore b e m ore C ases of both a reduction in groundcomple te. The best-known example of water availability to support ecosystem s such complete ecosystem dependen ce and an increase in groundwa ter availon a regio nal system is th e m ound ability are identified . springs of the Great Artesian Basin . Secondary asp ec ts used as signifiT h e identification of scale can be a cance criteria are uniq uen ess and useful indicator of ecosystem depen- vulnerabili ty . ' Unique ness' refers to dence, which can scale along the same nati onal biodiversity, cultural and continu um from local through interme- aesthetic con sideration s. 'Vulnerability' diate to regional. refers to the degree of dependence and A related distin ction is the recogni- sensitivity to changes in the availabili ty tion of two basic types of aquifer: those of groundwater. based on porous media and those based on fractured rock. Ge nerally, porous Assessing Dependence m edia have a less variable transmissivity M ethod s fo r assessing the dep enthan fractured rock , which makes them dence of ecosystems o n groundwater mo re likely to tran smit c hanges in are largely indirect, or based on the gro undwater levels or quality in a ass ump tio n that plan t and animal predictable way. groundwater use is evidence of depende nce . Few expe rimen ts have b ee n Groundwater Dependence â&#x20AC;˘ p erformed in this area. M ost of Australia has eith er seasonal In the case of terrestrial or streamside drought or a semi-arid to arid climate. If vegetatio n , tec hn iques based o n the groundwater exists within th e reach of ratios o f the naturally occurring, stable orga nisms, ecosystems that rely o n it to isotopes of 0ll.'Ygen and hydrogen have some exten t will develop. led to major insights into w hen and if T wo corollari es of thi s are that vegetation accesses d ifferent sources of reducing the availability of groundwater water, including groundwater. may result in a gradual , proportional In Australia this techniqu e has decrease in t he health or extent of a helped define the vegetation depengiven eco system and that many eco- dence on groundwater at a number of system s depend on groundwater not sites. These include river red gums becoming too available. along the Rive r Murray floodplain, In the first case, a threshold of avail- melaleuca stands in the upper southability may be reached at which the east of So u th Au stralia, ba nksia entire system collapses. Know ledge wo odlands on the Swa n C oastal Plain abo u t this ecosyst em response in and tropical woodlands near Darwin. Australia is limited. Pilot wo rk is b eing done on the In th e secon d case, ch anges in groundwater use of radiata pine. landuse have increased groundwate r The iso topic analysis technique has and especially saline di scharges. limitations. First an d fo rem os t, it C onsequently, they pose a major threat requires a difference in the isotopic to a wide variety of te rrestrial and signatures of soil water and groundWATER SEPTEMBER/ OCTOBER 1998

41


ENVIRONMENT ent catchments. They also reflect groundwater co n tributio n to some degree. Hydrographs for 117 catchments in Victoria indicate that the base flow for the greatest number of catchments comprises between 40% and 50% of the total stream flow. Of the 117 catchments, 91 are in a fractured rock environment and the remainder in alluvial sediments. As most Australian streams are in alluvial environments, it is concluded that in a similar climate the base flow component of many would be at least 40% to 50% . In different climatic regions of Australia, different conclusions would result. The significance with which ecosystems depend on base flow is more complex. It is considered that ecosystem dependence is not solely related to the base flow index, but more to the variability and predictability of flowa parti cular ecosystem may evolve because of a given degree of variability. Attempts to quantify ground'a reduction of this resource water discha rge necessarily affect the ecosystem' have been made for waterbodies like Philip Bay, but it is globally and in Australia that there is Port little doubt that LAI is a strong indica- not yet possible to separate the ecotor of water availability in semi-arid to system effects of surface water from arid environments. More formal treat- gro undwater, and n o work on the ments exist, such as an empirical specific ecological impacts of groundrelationship between climate indices water discharge has been done. In most and LAI , with we tlands ide ntifiable cases, the maintenance of base flow or outliers w ithin this frame work. river pools in semi-arid to arid envi ronDischarge from mound springs in the ments or through a dry season by means G reat Artesian Basin has been inferred of groundwater discharge is taken to be on the basis of the biomass the mound depende n ce of the local biological springs supported. A calibrated systems. biophysical model of forest water use and growth has identified the anoma- Summary of Australian lous growth performance of radiata pine Ecosystem Dependence stands in South Australia which may Given the large uncertainties regardhave been due to access to fresh local ing the role of groundwater in the groundwater. diverse ecosystems discussed above, the Ascertaining the importance of ecosystems of Australia can be classified groundwater to in-stream and estuarine by their probable degree of dependence ecosystems is far more difficult. In many on groundwater. cases, even the magnitude or relative Given the availability of fresh proportion of waters in these systems groundw ater, an ecosystem will use and originating from aquifers is difficult to become dependent on it and a reduction of this resource will necessarily assess. Flow duration analyses and estimates affect the ecosystem. of base flow contributions have not If groundwater were to diminish or been derived nationally, although they be modified only slightly, e.g. so that a have been done for Victoria, based on surface water system stopped flowing, ecosystem s entirely dep endent on objective analytical techniques. The base flow index can only be used groundwater wo uld cease to exist. fo r comparative purposes, since it Examples where this w ould occur reflects a range of processes contribut- include mound springs, channel watering to stream flow other than ground- holes, the Swan Plain lakes, saline lakes water discharge. These include bank and river red gum stands in the arid storage, capillary fringe effects, flow in zone. In ecosystems that are highly depenthe attenuated unsaturated zone and delayed surface flow. Nonetheless, base d ent on groundwater, moderate flow indices do provide a fairly objec- changes to groundwater discharge or tive basis for comparison across differ- watertables would lead to substantial

water, which does not always exist. Secondly, the technique is most effective when combined with flux measurements because the degree of use or dependence can be better assessed. Indirect means are based on an explicit or implicit wate r balance, with discrepancies between annual rainfall and actual (evapo-)transpiration ascribed to the discharge of local or regional groundwater. These inferences are rarely made explicit through longterm measurement, but are inferred indirectly from arguments based on potential evaporation, annual rainfall and the persistence of water at or near the surface of wetlands. Oth er approaches rely on changes in surface water or groundwater levels that can be associated with changes in flora and fauna. The hydrologic equilibrium between climate, soil, and biomass or 'leaf area index' (LAI) h as b een so repeatedly hypoth esised and sufficiently tested

will

42

WATER SEPTEMBER/OCTOBER 1998

decreases in the extent or health of the ecosystem. There is a significant chance that the ecosystem would collapse, but this is not entirely certain. Examples of sites that would be affected by such cha nges include waterholes on the Central Lowlands rivers that support swamp woodlands, sedgelands, canegrass and herbfields, R amsar wetlands and the stromatolite systems of coastal Western Australia. For a number of systems that h ave some dependence on groundwater it is likely that a unit change in the amount of groundwater will result in a proportional change in the health or exten t of that ecosyste m. In oth er words, if groundwater discharge were cut by half, one might expect some equivalent diminution of the ecosystem. Examples of systems w ith some d ependence on groundwater are numerous and widely dispersed throughout Australia. They are mainly swamps, damplands and upland bogs, but include volcanic lakes, river p ools in the tropics and a number of coastal lake systems. Groundwater may only play a significant role in the ~ater balance of some ecosystems that may use groundwater opportunistically, e.g. in times of extreme drought or briefly at the end of a dry season. Whilst this role of groundwater may be critical in the longer term, the immediate impacts of substantial groundwa ter reductions may be muted . Examples of system s that would be affected are mainly on the coastal fri nge, but include the ends of the inland rivers, e.g. Lak e Eyre.

The National Scale Ecosystems that are entirely dependent on groundwater represent less than one per cent of the land area of Australia, and a similar fraction is occupied by ecosystems highly dependent on groundwater. Those systems that are proportionally dependent on groundwater cover less than five per cent of the nation. However, given the general aridity and strong seasonality and variability in rainfall in most of Australia, these relatively well watered eco systems have an impo rtance far in excess of their geographic extent. M any of the ecosystems associated with groundwater disch arge fo rm the bases of many of Australia's national parks, particularly in the arid and semi- arid zones. T he systems identified as entirely d ependent on groundwate r are also quite unique, in that they are localised phenomena with a high public profile fo r their biodiversity, tourism, cultural heritage etc. Perhaps the only exceptions to this are the streamside red gum stands in the interior of the country. These are extensively distributed and


ENVIRONMENT depend on groundwater recharge as a result of floods. Much is known about the Great Artesian Basin mound springs, particularly in terms of their vulnerabilitythey are clearly vulnerable to local changes in groundwater pressure. The surface water- groundwater interactions maintaining the lakes of the Swan coastal plain are also relatively well u nderstood and their vulnerability to changing this regime and to pollutio n is clear. Much less is known about the vulnerability of the karstic groundwater ecosystems of Exmouth Cape, perhaps as a result of their distance from major centres and other developmen t. The channel waterholes and their catchment areas in the Central Australian Ranges are gene rally in conservation parks and may to some extent be considered less vulnerable. T h e saline discharge lakes of the western Murray Basin are regio nal groundwater features and would be vulnerable to changes in grou ndwater levels resulting from pumping from this aquife r. T he streamside e ucalypt woodland along the interior rivers of the arid zone depend on local channel rechargedischarge phenomena and only local impacts would be expected. T he highly dependent systems of the tropical far no rth (m esophyll vine forests, paperbark swamps) are cu rre ntly under assessmen t with respect to their vulnerability to groundwater developmen t. These systems occur in local patches across much of the top end of Au stralia, and must be seen as less unique from place to place than the other highly dependent systems. By contrast, river pool and spring ecosystems of the Pilbara are gene rally unique to their regions, and their confinement along rivers makes them more vulnerable to changes in the hydrologic regime. It is well appreciated th at many streams from the Great Dividing Range in sou th-eastern Australia are base flow streams highly dependent on grou ndwater discharge. Not enough is known regarding stromatolite formations to assess their vulnerabili ty, but they are clearly unique biological fea tures with a high public profile. Of the many systems identified as proportionally dependent on groundwa ter, a few are noteworthy w ith respect to uniqueness or vulnerability. The permanent coastal lakes of dunes and beac hridge plains 111 eastern Au stralia are subject to a variety of pressures. T hese include the development of groundwate r resources and pollu tion including acid sulphate run off. T he systems are not locally unique, but their proximity to urban and tourist centres gives them a high

public profile. They also have a potential importance to fisheries. Base flow, herbland, river pool and billabong communities in northern Australia are notable in terms of their biodiversity and biological importance to the region. The systems are potentially vulnerable to groundwater development, particularly w here demand for water resources is high , such as in northern Queensland.

Case Studies Three case studies highligh t th e biophysical, social and eco nomic complexities involved in evaluating the significance of ecosystem dependence on groundwater. T he firs t i s a study of water supply to the C ity of Darwin in the Northern T e rritory w hich focuses on resou rce development in a tropical savanna. T he dependence o f this ecosystem on groundwater has been studied, showing that it is likely that exploitation of the aquife r will adversely affect the health of the ecosystem. T he second study focuses on the effects on the surrounding temperate woodland of the u se of a major groundwater resource, which has been developed by the Barwon Water Authority as a drought security supply and to reduce the need fo r new surface water storages . to meet peak summ er demands. Management of lakes on the Swan Coastal Plain is studied in the third case study, the Perth Urban Water Balance Study, which was initiated in 1982 to develop regional scale u nderstanding of the water balance and the in terac tions between the hydrological balance and wetland features. A feature was the need to identify capture zones, water level management and effective parameters of groundwater models in planning fo r the flow- through lakes of the Swan Coastal Plain.

Maps and Literature Survey National m aps of the occurrence and distribution of grou ndwater-dependent ecosystems related to vegetation , wetlands and base flow systems have been prepared to complement the report. T he m ost salie n t spa tial feature of dependent ecosystems is their small, local extent. T his means that most of the dependent ecosystems ide ntified cannot be revealed at a scale of 1 :5 000 000. For instance, in the case of vegetation, large areas of Australia have been typified as acacia dominated by mulga and related shru bs not reliant o n grou ndwater, but within these regions there are vegetation types such as streamside red gums with strong dependencies. Such associations are identified on the map. The wetlan ds map attemp ts to

characterise the nature of wetland features such as permanent lakes and ephemeral swamps regionally. As a result, the detail of the diverse types of wetlands may be lost within a particular region of Australia. Nevertheless, there are characteri stic, dominant wetland types from region to region in Australia. As was done for the vegetation map, dependent ecosystems in each of the mapping units were identified on the wetlands map. There is no synoptic picture available fo r river base flow (or the grou ndwater contribution to base flow) for Australia. H owever, annual rainfall, aquifer rock type, and Australia's river systems have been mapped. Within this framewo rk rive rs can be assessed agai nst geographic, geological and meteorological zones and it is possible to indicate regions where ecosystem dependence on base flow and therefore groundwater is likely to be higher or lower.

Conclusion Ecosystems that depend on groundwater for their existence should be recognised as a key compo nent in Australian planning and groundwater allocati on processes. T h ese sh ould involve an assessment of ecosystem susceptibili ty analogous to vulnerability mapping for groundwater pollution. A clear methodology and policies to define acceptable impacts should be established. An emphasis research on base flow and wetland ecosystems is recommended, with base flow index as a national indicator of the importance of groundwater to total river flow. An analysi s of available historic stream gauging data across Au stralia could determine the relative importance of grou ndwater contribution to total stream flow. In relation to groundwater the translation of the 1996 COAG concept of provision for the environment is poorly defined. Planning must recognise ecosystem dependence on groun dwate r and related processes. This is perhap s best achieved through the development of groundwater management plans.

References An extensive literature search (400 references) was undertaken to describe all those cases throughout Au stralia where a dependence or lack of depende nce on groundwater has been demonstrated or inferred.

Authors Dr Tom Hatton is the leader of CSIRO's Vegetation and Catchmen t H ydrol ogy Research Group. Dr Richard Evans is Principal H ydrogeologist with Sinclair Knight M erz. WATER SEPTEMBER/OCTOBER 1998

43.


m Summary Goulburn Valley W ater has drafted a standard contract for the sale of recycled wate r that is available for interested parties to use in Victoria. With modificati ons to suit local legislation the contract can easily be used fo r other States and T erritories and by private water companies. This pap er discusses the issues considered in the contract, copies of w hich are available from the author free of charge.

Introduction D uring 1995

BUSINESS

WATER REUSE A STANDARD CONTRACT A Sherman required the approval of either the EPA or H ealth D epartment. N ow the situation is that if the reu se guidelines are satisfied , no formal licence or permit is required. Whilst m uch red tap e has been elimi nated, the comfort of clear min imum standards in some fo rm of legal consent has also been lo st. Future revisions o f the guidelines wo uld benefi t from so me inpu t from the legal profession. Additionall y, it is apparen t that agreem ents made before these regulations came into effect failed to adequately protect the supplier , customer and the environment.

Goulburn Valley R egion Water Au tho rity (GVW) obtained fund ing from Land care Australia to carry ou t legal research designed to create a standard contract for the sale of recycled water. Ru ssell Kennedy Solicitors were engaged to produce a draft contract, w hich w as t he n review ed by various Victorian water au tho rities and the Victo rian E nvironmen t Protec tio n Au t hority (EPA) and H ealth D epartm ent. Most of the suggestions were incorporated. Goulburn Valley Water is nego tiating a number of reuse proposals and has Focus on Process, Not fi nalised a pilot reuse agreem ent w ith a Legalities dairy operatio n . Part of the Landcare Potential suppliers have a decision to funding was provided to the dairy's make in adopting the n ew contract. solicitor for a critical analysis o f the W hilst it would be relatively easy for the contract as both a generic and specific wate r authority to say, 'Sold ... that is document. no longer our problem ,' the difficul ty is T he co ntract was made ge ne rally that there is a question of conununi ty available in an effort to promote i ts obligation. The water autho rity could adoption by others in the industry and it be the recipie nt of legal action in the has been u sed as a tool for reu se across · eve nt o f p ollution or gradual deterioraVictoria. W ith min or ame ndments, tio n of land quality . havi ng regard to the relevant legislation, An irn.portant point in proceeding the contract can easily be u sed by other with a proposal to sell recycled water is States and T erritories and by private to acknowledge tha t there is a tendency com pany selle rs and suppliers. to get caught up in the legal agreement as the ' be all and end all.' T his m ust be Victorian Legislation avoided. T h e agreem en t, alth ou gh Until 1996 in Victoria both the EPA important, is only one part of a m ultiand H ealth D epartment had regulatory face ted process which involves: control over the u se of recycled • a study o f demand, supply, current wastewater. The re was an ove rlap users, potential users, legal issues: in be tween the roles of those two govern- short a technical, economic and legal ment entities and th ere w as a need to analysi s t hat sh ould be underta ke n clarify that situation and importantly to before any comm ercial ven ture. If the simplify it. T he H ealth D epartment in reuse proposal is on a small scale, w hat Victoria then relinquished control to is the reason for having it? Are the costs the EPA which now operates a ' ... soft asso ciated with setup and the lower hand of regulation.' level of disposal security etc worth the T he introduction in 1996 of the benefit? Victorian EPA Guidelines for W aste• th e iden tification o f suitable water R eu se has freed up the way in purchasers and the commencement of which wastewater can be legally sold to negotiations. A copy o f the draft p rivate u sers in Victo ri a. T he new con tract can be provided then regulation s, however, put the resp onsi• preparation of plans and specificability for deciding w he the r or not an ti on s for th e site. H ow is water to be EPA licence is required on to the w ater applied and m on itored? What are the producer and potential customer. reporting requirements? Previously a legal reu se sc heme • the preparation of a final contract

that incorp orates the site managem ent plan as part of its conditions. Importantly, the standard or 'generic' contract is still only a starting point that w ill raise issues that may be of initial concern. After analysis th ese issues may b e safely addressed o r simply dele ted .

Contract Format Two types of con tract have now bee n prepared: one for th e sale o f recycled water to private landho lders, the subj ect of this pap er, and one for the sale of recycled water to fa rmers who lease water au tho rity land. The contract form, w hich is designed to make the process as simpl e as p ossible, com pri ses four parts: particulars, special conditions, general conditio ns and a site manage ment plan. T here is also an explanatory page that se ts out the reason fo r the doc ument and how it should be comple ted. Part D-Site Management Plan Although refe rred to as Part D , th e site m anagemen t plan i.s in many respects the most importan t part o f the con tract, as it contains th e practical, site- sp ecific issues w hich shou ld b e carefully conside red before any other part of the contract. It sets out: • quantities of water to be taken • the nature of application • types of crops to which the wate r can be applied • the area of any particular piece of land set aside fo r the particular use • storage arrangements • mon itoring arrange1nents etc. The site managem en t plan all ows flex ibility to use th e contract in vari ou s locations. Obviously, rates and method s of applicatio n will vary be twee n a property in n orth-western Victoria and a property in Gippsland, or in another climatic zone. It should be prepared jointly by the purchaser and authori ty, perhaps with the help of a con sultant. Part A-Particulars T his part of the agreement is selfexplanatory. An effo rt has been made to make it user-friendly by pointing the reader to various clauses in th e general conditions once they have comple ted the particulars. WATER SEPTEMBER/OCTO BER 1 998

45.


BUSINESS Because the site may form only part of a particular certificate of title, it needs to be clea rly designated in the site management plan. Of note is the fact that the site ow ner may not be the pu rchaser of the treated wastewater. The owner's consent to the use is therefore crucial. Provision is made fo r the owner's name to be incorporated in the agreement. By executing the agreem en t t he owner formally agrees to the use. Execution of the agreement by the purchaser, guarantor and owner of the land is provided for at the back of Part A. Part B-Special Conditions T h e contract should not be amended by removing or crossing out any of the general conditions. If, for example, the clause in relation to signs on the land (e.g. warnings) is to be deleted from the general conditio ns, there should be a special condition to the effect of: 'General Condition 'XY' relating to signage does not apply to chis contract.'

Special conditions can be added to cover arrangements that are not dealt with in the site management plan, for example: ' In addition to the sale of water the authority has agreed with the purchaser co supply additional assistance to the purchaser in the form of (Insert details such as monitoring or works assistance etc.]'

Part C-General Conditions The general conditions shou ld not be ' tinkered wi th' other than by clear amendment via a special condi tio n. Various aspects o f th e general condition s are detailed below.

Issues Covered How long the agreement should last is an important question. If an authority locks itself into supplying recycled water fo r 20 or more years and in due course the water resource becomes a more valuable product, the authority may have denied itself the potential to make an appropriate return from the product. Alternatively, an agreement which is too short that involves an extensive capital works investment is no t really viable. It is a matter of balancing the cost of getting the recycled water to the particular site with how lo ng the auth ority will have the b enefit of disposal at that site. At p resent the primary objective across most of Australia seems to be fi nding secure means of disposal rather than making large profits on the sale of recycled water. T he agreement allows for two options for the supply of recycled water: a fixed ann ual amount which t he 46

WATER SEPTEMBER/OCTOBER 1998

purchaser must take and a variable the agreement. If, for example, the amount depending on rainfall. The purch aser is simply unwi lli ng to problem with the fixed approach is that continue an agreement after a year, they if it rains for ten months of a year the must fu!J y repay the cost of the work. demand will not exist and the purchaser After the fi rst year the obligation to is more likely to take the water and repay decreases on a sliding scale. The infrastructure costs to be recovimproperly discharge it in some way. The second option is more practical. ered are secured by a charge on the This involves incorporating an irriga- owner' s land. This would allow the tion schedule into the site management supplier to lodge a caveat on the land. Option C is where the purchaser plan and agreeing to take a particular amount required d epending o n t he carries out and pays fo r minor works. U nder the contract any structure relevant weather conditions. The purc hase r cannot sue the relating to the reuse operation inside auth ority if it cannot supply t he the boundary of the land is owned by recycled water due to circumstan ces either the landowner or p urchaser. Any beyond its control such as: structure outside the boundary is the â&#x20AC;˘ a decline in input to the plant property of t he water autho rity o r â&#x20AC;˘ where water quality falls below the supplier. Consequently, each party is specified guideline responsible for maintenance of the part â&#x20AC;˘ the EPA or some othe r such body they own. orders the cessation of supply. If pipelines have to traverse the la'nd One of the crucial issues in relation of other prop erties to get the water to to recycled water use is the qu estion of the site and the seller is not a statutory who owns the wate r and when, or authority or other body with the power 'liability.' to create easements, appropriate rights A water authority is under an obliga- need to be privately negotiated to create tion to provide the resource in the best the easements. possible form with directions as to how to use it. After that, it is in the autho r- Water Quality ity's interests to ensure it is not going to As indicated in the discussion about be liable for any future improper use of EPA and H ealth Department water that water by a purchaser. quality requirements, the qu estion of T he best way to cover the authority what constitutes 'wastewater' is likely to in this regard is to ensure that the be a set of min imum standards in the recycled water is actually sold, so that new guidelines. property in it passes to the purchaser. If the water quality to be supplied in Under the contract, ownership of the a particular case is below the minimum property passes upon provision of the standards there are two consequences. , water regardless of w hen the water is Firstly, in Victoria the site is likely to paid fo r. require a works approval u nder th e Many other agreements are effec- Environment Protection Act 1970 tively joint venture or supply agree- (Vic). Secondly, the site management ments whe re the authority remains plan wi!J have to be more specific abou t actively and heavily involved and water quality components such as BOD . arguably is still the legal owner of the T he purchaser can refuse to take the water applied to the site. water if it fails to meet agreed.. standards. A fee of some sort, even if it is only some cen ts per kilolitre, must be Ongoing Monitoring of imposed in order to ensure the water Supply/Performance has been sold. Under the contract the purchaser Payment under the contract is fou rthe seller wi th half- yearly provides monthly in arrears. T his period has been adopted because it fits in with the estimates of future demand for recycled billing regimes of some of the Victorian water. T he purchaser is required to monitor authorities, and obviously i t can be changed. In Victo ria, care should be and report to the seller the impact of the taken by water authorities not to make recycled wastewater on the land. T he this an annual charge becau se there may agreement provides fo r monitoring to be a request for instalment payments be increased if there are any concerns. under the provisions of the Water Act Responsibilities 1989 (Vic). In most cases it is preferable for an Option A provides for the purchaser to pay the infrastructu re costs. If the agreement to be between the authority purchaser pays, this amou nt should also and a purchaser w ho is actually the su bstantially offset the cost of the owner of t he land. This avoids a number of potential difficulties. recycled water. One of these difficulties is that on O ption B provides for the au tho rity to bear the cost of the work and offers occasion the purchaser will not be the the purchaser an incentive to remain in owner of the land. Alternatively, a


BUSINESS purchaser may be a company and the autho rity will need to get a guarantee from the directors of the company. The contract makes provision fo r execution by the purchaser, guarantors and owner of the land. One of the reasons the owner's consent to an agreement is important is that if there is any ongoing damage caused to the land the owner may seek recourse through the water autho ri ty. The contract contains a waiver of this type of action and an indemnity in favour of the wa ter authority by both the purchaser and the owner.

Termination of the Agreement If the purchaser is in breach o f the agreement at any time in a substantial way and in a manne r w hich creates a serious environmental ri sk the authority can terminate the supply. If the breach is not so important but con tinues to occur on a number of occasions the authority can also terminate. Generally an authority would not be keen to terminate if it had invested su bsta n tial time and m oney in the wo rks and was looking to the land as a m eans of disposal. Obviously the authority would need to be con tent with the type of purchaser involved before any agreement was entered into. There is provision in the contract to recover the cost of the infrastructure works fro m the purc haser if th e purchaser has not already paid for them. This option is not available if the water au thority has agreed on some other arrangement wi th the purchaser of the type set out in Option C and the special condi tions. T he issue of tennination also raises the option of dispute resolu tion. In o rder to mini mise costs it is proposed that d isp u tes be arbitrated by an independen t arbitrator such as t he rel evan t B ranch President of t he Australian Water and Wastewater Associati on . Comment from W ater readers is sought on this aspect.

Other General Conditions O the r gene ral con ditio n s cover: • the obligation to hold all necessary permits • the obligation not to on-sell the water without the consent of the water authority • the obligation on the parties to pay thei r own legal costs in relation to the agreement • other general legal clauses relating to severance, waivers, notices, in terpretation and fu rther assurances.

Conclusion A need existed fo r an agreement to be created which sufficiently protected

the rights and obligations of a recycled water seller whilst creating a commercial proposition that is attractive to potential purchasers in terms of cost, risk and security of supply. The concept is defi nitely plau sible in the case where a water authority can supply an irrigation resource to people who previously did not have access to a supply or where the au thority can sup ply it at a much cheaper cost than another supplier (e.g. a ru ral water au thority). Finally, of critical importance is the attitude of the regulatory au tho ri ties to water recycling proposals. O n the one hand water au thorities are being entreated by the regulators to stop discharging to rivers and streams. On the other hand, whether it is true or not, water authorities perceive that they face significa nt red tape and risk w hen trying to prom ote a private re u se arrangement. T he situation to date has been that reuse has usually been to golf courses, council parks etc. and has often occurred without the necessary legal approvals. Water autho rities and private users are fo rced to rely on the discreti on and good graces of their relevant EP A and H ealth D epartment. C learly, water authorities and users should not continue to operate illegally. The Victorian reuse guidelines go part of the way towards addressing the problem of illegality, subject to the commen ts made earlier in this paper. What they do not do is remove from water authorities and companies their du e dilige nce obligation s w hi ch in many ways are in creased by the Victo ria n self regulation approac h . Some o f the increased or cha nged obligations are discussed above. O ne of the main objectives of this proj ect has been to avoid the situation where recycled water sellers and buyers have to reinvent the wheel each time they enter a private reuse agreement. T he authors strongly encourage any comment or criticism of the agreement and its ratio nale.

Acknowledgements The author ac knowledges with thanks the key role played by Peter McM anamo n , Director T echnical Services and Laurie G leeso n , C hief Executive O fficer of Goulburn Valley Water fo r instigating and running the p roject w hich gave rise to the contract.

Author Andrew Sherman is an env1ronme n tal law specialist and partner at Ru ssell Kenn edy Solicitors, 469 Latrobe Street, Melbourne Vic 3000, tel. (03) 9609 1555, fax (03) 9609 1600, email asherman@rk.com.au. WATER SEPTEMBER/ OCTOBER 1998

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Water Journal September - October 1998  

Water Journal September - October 1998