Water Journal June 1990

JOURNAL OF THE AUSTRALIAN WATER AND WASTEWATER ASSOCIATION

Registered by Australia Post -

Pi,blication No VBP1394

Official Journal

water

ISSN 0310-0367

Volume 17, No.3, June 1990

AUSTRALIAN WATER AND WASTEWATER ASSOCIATION

CONTENTS My Point of View . . . . . . . . . . . . . . . . . . . . . . .

Association News

President's Message . . . . . . . . . . . . . . . .

It Seems to Me . . . . . . . . . . . . . . . . . . . . .

IAWPRC News . . . . . . . . . . . . . . . . . . . . . . . . .

Personalities . . . . . . . . . . . . . . . . . . . . . . . . . . .

Industry News . . . . . . . . . . . . . . . . . . . . . . . . . .

3

Plant, Product and Equipment . . . . . . . . . . . .

36 37

4

Book Reviews . . . . . . . . . . . . . . . . . . . . . . . . . .

Wagga's Trade Waste Monitoring and Changing Program

C. Earnshaw . . . . . . . . . . . . . . . . . . . . . . .

37 39 40

4 9 10 11

Conference Calendar . . . . . . . . . . . . . . . . . . . .

People and Company News . . . . . . . . . . . . . .

Hydrogeology - Growth and Diversification S. Hancock .... ...... .. .. ............ 12 Waste Water Disposal by Aquifer Injection L. Drury . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Groundwater Pollution in Australia - Problems, Policies and Challenges

A.P. Lane . . . . . . . . . . . . . . . . . . . . . . . . . .

.I

OUR COVER Test-pumping of confined and unconfined aquifers from the Kingston .

Lignite Project in South Australia. The ~ . tests revealed that depressurisation ~'1 - and dewatering of the mines could '"l • have demanded pump-out discharges . , • of over 160ML/ annum at the peak of }:~ · the project's 37 year life. Computer .;.¥~. modelling predicted far-reaching =-"J::.- impacts in both areal and environ·,.......r mental senses.

Extensive studies were then unckrtaken into the impacts on wetlands, regional water supplies and agriculture. Mitigation programs were devised, innovative mining techniques developed, and re-injection strategies implemented.

This project typifies the diversification away from traditional groundwater engineering stimulated by studies of the hydrogeological interactions. (see also page 12)

16

Groundwater Contamination Assessment of Gasworks Sites

R.J. Parker and R.D.A. Wolfe . . . . . . . . . .

20

Environmental Impact of Irrigation without Adequate Drainage, Kerang Region, Northern Victoria, Australia

R.C. Lakey . . . . . . . . . . . . . . . . . . . . . . . . .

24

Disposal of Residue from Ti02 Production

J.E. Bawden, A.C. Deeney, R.J. McGowan and P.T. O'Shaughnessy . . . . . . . . . . . . . . . . . 27 Waste Disposal and Groundwater Management Issues in Jakarta, Indonesia

P. Whincup . . . . . . . . . . . . . . . . . . . . . . . .

32

Cross Flow Technologies in Water Treatment

C. Fell . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Conference Notices . . . . . . . . . . . . . . . . . . . . .

Letters to the Editor . . . . . . . . . . . . . . . . . .. . . .

FEDERAL SECRETARIAT PO Box 460, Chatswood NSW 2057 Facsimile (02) 410 9652 Telephone (02) 413 1288 Office Manager - Margaret Bates

FEDERAL PRESIDENT Peter Norman Telephone (08) 226 2249

EXECUTIVE DIRECTOR Peter Hughes Telephone (02) 410 9654

FEDERAL SECRETARY Greg Caws to n Telephone (042) 29 0236

FEDERAL TREASURER John Molloy Telephone (03) 615 5991

33 35 35

BRANCH SECRETARIES Canberra , ACT f' Cox, PO Box 306, Woden 2606 (062) 498 522

New South Wales Mr David Hope, PO Box 460, Chatswood 2057 (02) 410 9402

Victoria J. Park CI· Water Training Centre, PO Box 409 , Werr ibee 3030 (03) 741 5844

Queensland D. Mackay, PO Box 412, We st End 4101 (07) 840 4844

Cover by courtesy of AG Consulting Group Pty Ltd

APOLOGIES! To MEMTEC Pty Ltd. In our cover story

in the April issue the words 'Crossflow Micro Flotation' should have read 'Crossflow Micro Filtration'.

South Australia R. Townsend, CI· State Water Laboratories, E&WS Private Mail Bag , Salisbury 5108 (08) 259 0244

EDITORIAL CORRESPONDENCE E.A. Swinton, 4 Pleasant View Crescent, Glen Waverley 3150 Office Phone and Autofax (03) 560 4752 Home (03) 560 9306

Western Australia A. Gale, PO Box 356, West Perth 6005 (09) 242 4677

Tasmania A.B. Denne, PO Box 78A, Hobart 7001 (002) 30 5562

Northern Territory D. Hardiment PO Box 37283, Winnellie 0821 (089) 41 0144

ADVERTISING Ann Sykes, Applta, 191 Royal Parade, Parkville 3052 (03) 347 2377 Fax (03) 348 1206

PRODUCTION EDITOR J . Grainger, Applta, 191 Royal Parade, Parkville 3052 (03) 347 2377 Fax (03) 348 1206

WATER June 1990

WASTE WATER DISPOSAL BY AQUIFER INJECTION

by L. DRURY SUMMARY The practice of disposing of waste water by injection to the subsurface is quite common in the USA and Europe, but is little practised in Australia. However, due to increasingly stringent environmental regulations and controls on surface disposal, interest in this method is quickly developing.

This paper reviews the present practices of aquifer injection in Australia and the criteria recommended to be observed in site selection of waste water borehole injection systems.

Dr Len Drury obtained his degree and doctorate in geologylhydrogeology from the University ofNew South Wales. After working for the Department of Water Resources, NSW, he joined Coffey Partners International in 1982 and is currently Principal Hydrogeologist. Dr Drury has worked on 65 mining projects throughout Australia, South &st Asia and the Pacific, many of which involved mine waste water disposal.

PRESENT PRACTICE To date the most common use of injection (recharge) has been to artificially increase the safe yield of alluvial aquifers. In Queensland, surface trenches and weirs are used to impound water ¡ and induce infiltration to aquifers in the Lockyer and Callide Valleys (Lane and Zinn 1980; Henry and Palmer 1980), Proserpine River (Pearce 1980) and the Burdekin River (Jackes 1980). In New South Wales, the alluvial aquifer supplying water for Kempsey town water supply is recharged by pumping water from the Macleay River into abandoned palaeochannels which traverse the wellfield area (Merrick Ross and Blair 1987). Mt Newman's wellfield in WA is also recharged by surface water sources.

Shallow subsurface disposal of domestic effluent has been practised throughout Australia for many years.

Large scale systematic direct borehole injection really commenced with brine injection in oil fields for secondary oil recovery.

Liquid waste disposal by injection to groundwater via boreholes has only developed recently in Australia, but already incorporates a large range of liquid types. Injection into the groundwater system is practised for a number of purposes, not always for waste disposal.

The possible consequences, and criteria to be observed in site selection and operation are discussed in this paper. The purposes for which borehole injection is or could be carried out in Australia include: Urban Industrial Wastes. This is typified by injection into deep boreholes of liquid waste from wool scouring operations and chemical plants in the Kwinana area, WA. Rural Industrial Wastes. Important examples are the disposal of cheese and butter factory wastes in South Australia and Victoria; washing water from sultana drying in Victoria; starch factory wastes in New South Wales.

Municipal Wastes. Stormwater is discharged to the groundwater system at Warrnambool in Victoria. Treated sewage has been discharged to groundwater in parts of South Australia.

Mine Dewatering. Subsurface injection is an option for disposal of water from mine dewatering. Coffey Partners International Pty Ltd (CPI) is currently undertaking feasibility studies for a number of large and small scale mining operations.

Insitu l.eaching as a Mining Method. Insitu mining is a process in which a liquid, usually an oxidising leach solution, is pumped through an orebody via an injection bore. The leaching solution migrates through the orebody (aquifer), mobilising the target mineral into a soluble complex. The pregnant liquor is then recovered through one or a number of pumping bores. The method can be used to leach economic minerals (e.g. gold, copper, silver, potash or uranium) . After extraction of the metal, the technique produces a large volume of liquid waste which is usually disposed of by injection into deep aquifers.

No insitu leaching is being conducted at present in Australia but a number of feasibility studies have been carried out and it is likely that such mining will soon commence.

Oilfield Brine Injection. Brine injection is a common procedure used worldwide for both disposal of brine, and for secondary hydrocarbon recovery.

Construction Sites. Water injection to aquifers is sometimes carried

out at construction sites where dewatering of excavations is necessary. The injection is designed to maintain groundwater 14

WATER June 1990

conditions in the vicinity of the excavation at their pre-construction level, to minimise subsidence and possible consequent damage to buildings and services. Disposal of contaminated water for such purposes is sometimes used.

Brine Disposal, Murray Basin. Saline water is a hazard in much of the Murray Basin, and large volumes require disposal wherever shallow water tables have been lowered by groundwater pumping.

Studies have been conducted into evaporation, concentration and subsurface disposal of the resulting brine, but the technique has not yet been put into practice.

Groundwater Barriers. In some parts of the world, injection of water has been used to create a groundwater pressure mound to protect a valuable groundwater resource from incursion by adjacent poor quality water. Most notably, such schemes have been constructed to protect coastal aquifers from seawater encroachment. A number of schemes have been examined in Australia, but none have yet been implemented. Hydrocarbon contamination,has been retained and recovered by artifically induced groundwater pressure mounds around the pollution plume.

Although the disposal of liquid waste into a groundwater system usually involves relatively small quantities of fluid, any injection into groundwater requires careful prior study and analysis. The waste liquid may be toxic and/or aggressive, and stringent conditions are required to ensure successful disposal. These conditions relate both to the design and construction of the injection facilities and to the effects on the local and regional groundwater system. In a successful disposal scheme, the injected fluid should all reside in the target formation, and there should be no leakage to ground surface of either the injected fluid or of any other fluid displaced by its injection.

CRITERIA FOR SITE EVALUATION Criteria for the evaluation of sites for subsurface waste water disposal in the USA are defined by Van Everdingen and Freeze (1971). These criteria are used by CPI as a basis for studies in Australia.

Regional Geological and Hydrogeological Considerations

In evaluating the feasibility of subsurface waste water injection, the initial requirement is for suitable hydrogeological conditions to be available.

An areally extensive, thick, sedimentary or highly fractured volcanic sequence should be present to provide a suitable repository for the injected liquid. The target aquifer preferably should be overlain by a confining layer and geological structure should not be complex, with little cross faulting and folding . Complex geological structure with multiple structural lineations complicate the prediction and monitoring of waste water movement and provide avenues for escape of waste water. The region should not be an area of groundwater discharge for the aquifer interval being considered and the target aquifer should contain either saline water or water of similar quality to that being injected. There should be an absence of mineral resources (e.g. gold, copper, oil, gas, coal) so that degradation or possible dissolution of natural resources is minimised. Since deep aquifer, high pressure injection may stimulate earthquakes the injection site should not be located in potentially seismically active fault areas.

Local Evaluation of Aquifer and Disposal Water Interaction Hydrodynamic, physical, chemical and biological factors must be studied in assessing the suitability of aquifer injection. Clogging, erosion or fracturing of aquifers may have deleterious consequences on the long term performance of the injection wellfield system.

Chemical compatibility of waste water with the aquifer receptor water needs to be assessed to avoid chemical precipitation, fissured formation dissolution, or swelling and dispersion of clay minerals.

Introduction of micro-organisms in the injection system may lead to clogging of the well/aquifer interface.

Waste water repositories should have sufficient borehole exposure, porosity and permeability to accept the quantity of injected fluid without necessitating excessively high injection pressures. The injection bores should be designed so that there is slow lateral movement of fluid into the aquifer. A homogeneous aquifer is preferred to prevent excessive "fingering" of the waste water/ formation water contact. Overlying and underlying confining beds should be present. No unplugged or improperly abandoned bores penetrating the disposal site should be present as this may lead to cross aquifer contamination.

Hydrodynamic Criteria Numerous reviews of the hydrodynamic criteria of waste water _injection have been carried out in the USA and Europe, e.g. Bear (1972, 1979), Huisman (1970), Witherspoon and Newman (1972) and Olsthoorn (1982). Basically the hydraulic relationships developed for groundwater extraction and for aquifer injection are diametrically opposite. Modelling techniques developed for regional hydrogeological assessments and wellfield extraction can be applied analogously to pressure interference effects at the injection wellfield.

The injected water flows from the well into the aquifer by raising the head of water in the hole. The injection bore can be sealed and pressure applied to the well and thus high injection rates can be achieved. The thickness and permeability of the receptor aquifer and the viscosity of the injected fluid control the differential pressure required per unit rate of injection. The porosity and thickness of the porous receptor determines the volume of fluid to be stored per unit area. Differential pressures and injection rates are also controlled by geological constraints, such as the areal extent of the aquifer, destruction of confining horizons at high differential pressure, and / or fracturing of the aquifer structure due to high inflow velocities and pressure.

The local and regional hydrogeological regime must be understood in sufficient detail to enable confident prediction of the route and time frame of injected water through the aquifer, and to be sure that there will be no return of the injected waste water to the surface.

Physical Criteria The clogging of an aquifer by the presence of particulate matter in the injection water is an obvious and serious consideration that needs to be addressed. Plugging by iron compounds, organic debris, silica or clay minerals and colloidal particles occurs by the formation of a semi- impermeable filter cake on the well screen or filter pack/ aquifer interface, or by deep aquifer penetration, (Figure 1).

Treatment of the well screen at the interface is relatively easy using standard well-remediation techniques, but successful removal of particulates once they penetrate the aquifer pore structure is difficult to achieve. In addition, entrained gas in the aquifer may significantly reduce permeability in a similar manner to plugging by solid particles, (Figure 2). /

REMOVE BY BACKWASH ING 8 J ETTING

F ILTER CAKE

IN AQUIFER

BLOCKAGE OF AQU I FER PORE

,.

GAS BUBBLES\

AQUIFER BLOCKED BY GAS BUBBLE

¡Fig. 2 -

Aquifer blockage by gas bubble held by surface tension.

Suspended particulates can be partially removed before aquifer injection by surface filtration. There appears to be no proven relationship between the concentration of particulates in injection water and the clogging of the wells. The Modified Fouling Index (Schippers and Verdouw, 1980) is used in CPI studies to assess fouling potential to injection wells in aquifers with intergranular permeability. Olsthoorn (1982) developed an empirical relationship between MFI and clogging rates which indicated that clogging due to particulate concentration is proportional to the injection velocity.

Injection velocities greater than lm/ hour (0.3mm/sec) can be avoided by proper well construction and wellfield design.

Elimination of entrainment of air and gas may be achieved by operating a closed pressurised system from water source to injection wellfield. Correct design and pressure control in the transport conduit and injection pipework can reduce the release of dissolved gases from solution.

Fracturing and Erosion of Aquifer Structure Hydraulic fracturing of a rock formation occurs by the injection of water at sufficient pressure to overcome confining stresses.

Hydraulic fracturing, caused by waste water injection into the aquifer system should be avoided, as escape of the injected fluid to other aquifer systems or to the surface may occur. Excessive entry velocity of the injection fluid and the dissolution of the intergranular cement by radical differences in aquifer chemistry could erode the granular structure of an unconsolidated aquifer and reduce its permeability.

Chemical Criteria , Injection of waste water may disturb the steady state chemical equilibrium of the aquifer system. Mixing of different water types may lead to precipitation or dissolution of minerals depending on their stability and ion solubility. Low pH water will dissolve calcareous cements and high pH may remove siliceous cements. In fractured carbonate aquifers permeability may increase due to dissolution of the aquifer. However, in granular aquifers, permeability will be reduced if precipitation of minerals (e.g. calcium and magnesium carbonates, iron, aluminium, manganese) occurs. Iron precipitation is particularly serious due to the abundance of iron in some natural groundwater systems.

Exposure to waters of different chemical composition can induce clays within the aquifer to swell or disperse. The montmorillonite clays are prone to swelling which, if it occurs, will restrict the flow of the injected fluid. The non-swelling clays (illite and kaolinite) may disperse and move with the injected fluid through the aquifer to be captured by drag forces at pore constrictions. The dispersion and swelling of clays during injection have been described by Hewitt (1963), Land and Baptist (1965), Mungen (1965) and Khilar (1983).

Biological Criteria Torrey (1955) and Kalish et al (1964) discuss the development of micro-organisms in groundwater. A variety of bacteria, fungi and algae occur in groundwater. Algae require sunshine to grow and fungi require oxygen for their metabolism; both can be excluded in an injection wellfield if a closed pipeline system is installed.

Bacteria occur in groundwater under various salinity, temperature, pressure and oxidation/ reduction states and can occur in injection systems where the natural equilibrium is disturbed. Most problems of this type relate to the production of hydrogen sulfide gas and clogging at the well screen or filter pack/aquifer interface. Cleaning of the injection well clogging due to bacterial growth can be achieved by using strong oxidising agents such as chlorine or hypochlorites.

TH ICKNESS OF CLOGGING LAYER

continued on page 26 Fig. 1 -

Aquifer blockage by sediment content in injection water.

WATER June 1990 15

GROUNDWATER POLLUTION IN AUSTRALIA PROBLEMS, POLICIES AND CHALLENGES

by A. P. LANE ABSTRACT Groundwater sources provide about 180/o of the total water usage in Australia. Translated into human terms, this means that about 580 communities around Australia or approximately one million people, use groundwater for all or part of their drinking water supply. Groundwater in many of our less urbanised areas also represents a vast undeveloped resources which will inevitably be utilised in the long term but only if the resource has been protected from pollution. Groundwater is also a key element of the natural environment because it provides baseflow to streams and wetlands, thus sustaining important ecosystems in dry periods. Pollution of groundwater is a potential cause of significant detriment to public health, environmental quality and long term water resources . management. The occurrence and significance of groundwater contamination in Australia is currently under review and preliminary findings are available.

The challenges which this problem poses for industry and governments in Australia are substantial, though possibly not yet as daunting as in some other countries. The first major requirement is for governments to seriously address groundwater protection policy, based on adequate information and competent hydrogeological assessments and guidelines. This in turn will present a challenge to industry to ensure that their groundwater protection forms part of their environmental management plans and is responsibly implemented. This emerging area of professional activity will be dependent upon attracting sufficient numbers of technical specialists in the hydrogeological and environmental engineering disciplines - a major challenge to our universities.

These challenges and responsibilities will also bring opportunities.

The service industries which government and industry will require to implement groundwater protection policy will need to rise to the occasion with professional, competent and timely advice and service delivery. What is the current preparedness of Australia's "polluting industries", academia, governments and service industries to address these challenges and opportunities?

INTRODUCTION Contamination of Australia's groundwater resources and the resultant undesirable effects on the environment and humans has been a growing concern among the public and water managers in many countries for some years. Australians have long been aware of the problem and in the first comprehensive publication on groundwater in Australia (AWRC, 1975), the threat of contamination from "waste chemicals ... percolating from the surface ... " was clearly recognised. In 1979 a conference in Perth sponsored by the Australian Water Resources Council (AWRC), documented numerous cases of groundwater contamination and showed the general level of concern about these matters in the water sector.

Some of the notable incidents documented at the time included the contamination by industry of saline aquifers in the Western suburbs of Melbourne, the increase in nitrate contamination in the shallow aquifers of the south-east of South Australia, the contamination from industrial waste lagoons in the Perth coastal plain, industrial contamination of the Botany Sands in Sydney and others around Australia. While this listing of incidents suggests widespread impact on the Australian environment through groundwater contamination, the scale and significance of these incidents was not well understood. Consequently, a survey of groundwater pollution incidents was commissioned by the groundwater committee of AWRC to attempt to define the seriousness of the problem. An internal report by the Bureau of Mineral Resources resulted from the study which presented an insight into 106 groundwater contamination incidents for which data was available.

Recently, the growing pressures for change in the regulation of environmental protection and the increased sophistication of the water resources management sector has resulted in an acceleration towards implementation of groundwater protection policies around Australia. Some states have already commenced development of 16

WATER June 1990

Anthony Lane is Principal Hydro geologist with Dames & Moore in Melbourne. He graduated MSc Hydrogeology in London in 1981, and worked for Mines Department Victoria, CS/RO and some consulting companies, before forming AHi, which is now a subsidiary ofDames & Moore. He has participated in projects in Australia, S.E. Asia and the Middle E:ast. He is also a parttime lecturer at RMIT, where he revised the syllabus for Hydrology. groundwater protection policies while others are waiting for the results of the latest AWRC study (by Dames & Moore) to define the seriousness of the problem and devise groundwater protection guidelines. An AWRC workshop held in Melbourne in March accepted the guidelines subject to some modifications. The guideline document will shortly be finalised and presented to AWRC Water Resources Management Committee for subsequent publication.

Independent of this guideline development process, the problem of contamination of industrial land and definition of clean-up criteria continues to drive the groundwater contamination issue.

The protagonists in this theatre are usually the land developer, the consultant and the environmental authority. Often the matter of criteria is resolved arbitrarily rather than with regard to the significance of the groundwater contamination problem or the broader policy framework. The need for rational development and implementation of a groundwater protection policy is therefore becoming critical. , The development of such policies requires a sound framework, to appreciate the significance of groundwater in the environment, the status of present contamination, the nature and distribution of contamination sources, the assessiÂľent of risk of contamination and the development of a suitable strategy to implement protection policy in the regulatory framework of the different states. This paper characterises this framework and discusses the challenges to industry and government which arise.

The distinction between groundwater contamination and pollution should be made here as this paper will mainly refer to "groundwater contamination". Contamination occurs when substances are introduced into an aquifer, however pollution has occurred when the contamination reaches a level that restricts the beneficial uses of groundwater. Pollution has a legal definition and use of the term will be avoided in this report.

THE NEED FOR GROUNDWATER PROTECTION Groundwater in the broad sense is all water which occurs below the land surface within the "Hydrologic Cycle". It is ubiquitous,

Leachate from a municipal landfill heads towards the groundwater.

interacting with the land surface, streams and lakes but because it occurs below the surface it is generally poorly understood and its occurrence and movement is often not appreciated.

Groundwater plays a significant role as a source of water which sustains life either as a source of Drinking Water or as a source of Environmental Water in surface waters such as streams and wetlands; and is a component in the broader context of Water Resources Management as the storage space in aquifers can be used to balance surface water surpluses and deficiencies across basins.

Underlying each of these is the economic value of groundwater, particularly where it is used as a source of water that would need to be replaced, at some cost, should that groundwater become polluted.

Public Health: Groundwater is commonly used as a source of drinking water in some parts of Australia and overseas, although in the experience of many Australians living in eastern capitals, it is possibly perceived as being unimportant.

The need for protection of groundwater supplies can be illustrated by the wide distribution of usage around Australia. In fact, 18 per cent of Australia's total water use, including drinking water, irrigation and industrial water use, is derived from groundwater sources. Figure 1 shows that Perth has a high degree of reliance 9n groundwater for drinking water supplies while Geelong, Newcastle and Darwin also use substantial amounts of groundwater for public drinking water supply. However the importance of groundwater as a source of public water supply is best illustrated in Table I. It can be seen that groundwater is the principal source of drinking water for about 600 communities, or a total population of almost one million people across Australia.

realised, partly as a consequence of the emergence of contaminated groundwater into streams and wetlands. However, the environmental value of groundwater is not evident in many situations due to the otherwise poor quality of the groundwater. Contamination of brackish water aquifers, particularly where they are highly permeable, can lead to serious degradation of the surface waters receiving such groundwater discharges . Consequently, the environmental value of groundwaters can be the critical factor determining protection measures in some cases. For example, the clean-up of the Bayside Project site in Melbourne requires groundwater quality to be improved to a standard compatible with the nearby marine environment.

Given the ubiquitous nature of groundwater and that it discharges to most streams and wetlands, the dependence of surface water quality on protection of groundwater quality must be appreciated in policy formulation.

Water Resource Management: Groundwater not only represents an important source of public water supply and environmental water but aquifers (with favourable hydraulic properties) present a valuable component in water resource management systems. For example, the aquifer can be used as a conduit for inter-basin transfer of water; it can be used to store surplus surface water or it can be used by industry as an economic substitute for reticulated drinking water, particularly in cases where lesser quality water is acceptable. Given the recent trend towards evaluation of groundwater resource developments in lieu of new surface water storages, the role of our groundwater basins in long term water resources planning requires careful consideration of basin protection.

SOURCES OF GROUNDWATER CONTAMINATION Table 1- Populations and Communities served by groundwater in Australia.

State

ACT NSW NT QLD SA TAS VIC WA TOTAL

Towns

Population Served

0 160

0 100,000 54,408 214,500 48,800 0 57,900 468,600

54 203

NIA NIA 61 11 3 591

• • • •

944,208

Source: Dames & Moore telephone survey of state water agencies NIA . Not Available

Overseas, the reliance on groundwater for public water supply is even greater than in Australia. In the USA groundwater accounts for 38 per cent of the total water supply and 34 of the 100 largest cities in the United States and 50 per cent of the total population rely partially or completely on groundwater.

Most European countries derive over 50 per cent of their total water supply from groundwater. For example, groundwater provides approximately 30 per cent of all public water supplies in Britain and up to 70 per cent in some regions.

Environmental Protection: Recently, the role of groundwater as a significant component in the physical environment has been

Sydney Melbourne Ade!oid e

IXZI

Total Water Use

Perth

Brisbone NewcostleConberro Gee!ong

ffl

Groundwater Use

Fig. 1 - Groundwater use in Australian cities.

Hobart

Sources of groundwater contamination are often categorised into either "Point Source" or "Non-point Source" to distinguish between those which have an identifiable origin such as a landfill or an industrial complex and those that are derived from numerous small sources or widespread land-use practices. While these categories are helpful in an introductory discussion, a more detailed analysis has shown that discrimination of other factors is more illuminating.

These factors are:

Da rwin

Pathways Source facilities Source activities/industries Contaminant species Pathways: The pathways for groundwater contamination can either be direct or indirect. The direct pathway includes discharges into a point source structure designed to access groundwater, such as a bore, shaft or sink hole. For example, a bore which intersects both a shallow polluted aquifer and a deeper unpolluted aquifer, might cause contamination of the deeper aquifer if the bore were improperly constructed or subsequently failed through corrosi'on of the casing. The indirect pathway is more common and requires the contamination to enter the groundwater via seepage through the soil and vadose zone. This pathway can be associated with either point sources or non-point sources such as wastewater lagoons, leaking tanks and some agricultural practices and can include contamination by atmospheric fall-out.

Source Facilities: The specific source facilities which are often identified as point sources of contamination are many and varied and are not unique to a particular industry or contaminant type.

These facilities include, wastewater lagoons, soakage pits, storage tanks, septic tanks and landfills.

Source Industries/Activities: A more useful categorisation of contaminant sources can be achieved by reference to the industry or activity which caused the contamination. This approach also enables a working correlation to be made between source and contaminant type. Industries or activities which operate the above facilities include; Water supply and wastewater utilities, Transport Industry, Local and State solid waste utilities, Agriculture, Waste disposal/treatment industry, Chemical and Petroleum Industry and Mining & Mineral Processing.

Accidental spills of hazardous materials are a source of contamination common to most industries using or transporting these materials. Another ubiquitous source of contamination which has been identified in Europe is atmospheric fall-out and contaminated precipitation.

Contaminants: Contaminants in groundwater can be categorised into three broad categories; Chemical, Radioactive and Biological.

WATER June 1990

17

The vast majority of contaminant species of concern to water resource managers occur in the chemical contaminant category.

Chemical contaminants can be classified as organic or inorganic and the number of chemicals which can occur in groundwater amount to several thousand species. However, a short list of "priority contaminants" has been compiled, based upon the USEPA lists of chemical contaminants and is presented in Table 2. More detailed discussions of the materials and processes used by various industries and their wastes can be found in specialised chemical engineering texts such as the Kirk-Othmer Encyclopedia of Chemical Technology.

The study also revealed that, although data might not be available for many incidents, the state authorities have-general concerns about groundwater contamination in certain areas or sites. Similarly, concerns for the future protection of areas potentially threatened or of high value were documented for each state. The greatest need identified during the study was for the development of a rational basis for groundwater protection policy. The authorities know they · have a problem; they need a means for establishing priorities for the protection of groundwater.

PROTECTION POLICY DEVEWPMENT Table 2 • • • • • •

Priority Contaminant Groups

Heavy Metals Inorganics (nitrate, cyanide etc.)

Phenols & cresols Phthalates Monocyclic Aromatic Hydrocarbons Polycyclic Aromatic Hydrocarbons

• • • • •

PCBs and related compounds Halogenated Aliphatics (TCEs etc) Pesticides (chlorinated organics) Radionucleides Bacteria

• Virus

STATUS OF GROUNDWATER CONTAMINATION IN AUSTRALIA A study of groundwater contamination in Australia conducted . by AWRC provided an initial characterisation of the situation in 1987. Figure 2 illustrates the frequency of occurrence of several sources of groundwater contamination. However, that study was constrained by the availability of data and generally it reported incidents which had been the subject of study by state authorities.

Consequently, the distribution of incidents between states possibly reflected the level of funding for groundwater pollution studies in the states rather than the actual rate of occurrence. For example, it reported 31 incidents in Victoria but only 8 incidents in NSW. The recent AWRC study by Dames & Moore did not concentrate on the time-consuming task of updating this inventory but documented the major areas of contamination in each state and characterised the types of contamination deriving from various sources in each state. Almost all states identified the following principal groundwater contamination problems in their jurisdictions: • • • • • • • • • •

landfills, stockpiles or contaminated soil producing leachates wastewater lagoons, spreading grounds and septics agricultural wastes and pesticide use manufacturing industry having hazardous materials and wastes mining waste and mine water leaking underground storage tanks contamination via bores accidents and emergency response (fires & spills) energy generation and Town Gas sites urban stormwater and atmospheric fallout.

FOOD PROCESSING WASTE 10.4%

INDUSTRIAL WASTE 30.2%

& SPILLS 12.3%

SEWERAGE LAGOONS LANDF ILL LEACHATE 13.2%

Fig. 2 -

18

& SPREADING 21.7%

Analysis of sources of contamination incidents.

WATER June 1990

The need for protection of groundwater is well demonstrated but achieving it requires a strategic approach involving; setting objectives, designing a protection policy and programs and assuring effective implementation within the legal framework.

The overall goal of groundwater protection should be to protect the groundwater systems of the state to ensufe that the groundwater can support the highest potential beneficial use in a sustainable, economical and socially acceptable manner. Therefore the underlying principles of policy formulation are: • Guidelines for Protection need to be sufficiently flexible to enable adaption to the different state institutional settings, • Polluter Pays principle applies, requiring the responsible party to recognise the need and make financial contingency for the cost of protection, • acceptance of Beneficial Use for classification and assigning value to volumes of groundwater, • an assessment of the Risk of Contamination is required to prioritise the need and degree of protective measures.

The establishment of Groundwater Protection Guidelines for Australia was the main objective of the recent AWRC study which is not yet complete, however, the preliminary findings are in accord with the above aims and objectives.

Groundwater System Classification Groundwater systems need to be classified in the protection policy development process because not all groundwater is of equal value nor is it equally vulnerable to contamination. The beneficial uses which have been adopted for this purpose are: • human consumption and food production, • industrial and agricultural use, 1 • ecosystem support, • no definable beneficial use.

The first conceptual hurdle to overcome in developing a classification system is that groundwater systems are much less homogeneous and complex than surface water systems. They are in fact four dimensional. At any location there can b~ several aquifer systems at different depths in the basin and each of these has time variable characteristics. This presents a problem when classification of groundwaters is attempted. Groundwater systems can be defined on the basis of "areas", "aquifers", "groundwater flow systems" or "groundwater basins". Given that maps are used to present the information the most expedient means of classification is by areal extent.

The second part of the classification problem is the definition of "vulnerability". An aquifer is vulnerable if it has hydraulic properties and/or a Jack of cover material which would result in rapid transmission of contaminants into the aquifer. Vulnerability is determined by a number of physical and chemical properties of the soils and aquifer materials, the rate of groundwater flow and the degree of interconnection with surface water bodies. A number of groundwater vulnerability mapping systems have been developed which take account of these factors (USEPA, 1987; Le Grand, 1970).

Pollution Risk Assessment and Protection Measures The risk of groundwater pollution in one or more classified areas can then be assessed for a given contaminant source or a range of potential sources. Chemical databases can be used to identify the potential hazards presented by a particular industry or process.

However, such risk assessment will be dependent upon competent hydrogeological assessments of the groundwater setting, the potential for contamination to occur and the likely fate of the contaminants. Groundwater models are already everyday tools used in this process and it is likely that in future the process could be automated to some extent by the use of "expert systems".

A range of protection measures can then be proposed for a particular site or general area, ranging from "no action" to prohibition

of the activity or clean-up of the site. This system of "Levels of Action" can equally apply to point source and non-point source problems. Definition of the activities and documentation required for each of these levels is currently being prepared as part of the.

AWRC study referred to above.

An additional protection measure, which can be independent of the classification system, is the use of Wellhead Protection Plans.

These apply to the design, installation, operation and maintenance of bores used for public drinking water supplies and are intended to protect the supply and thereby protect public health. The plan should ensure integrity of the bore liner; recording of crucial data on bore performance; control land use around the bore and in particular the use and storage of hazardous materials. These are commonly used in Europe as the primary means of groundwater protection.

Protocols and Standards In order to facilitate uniform application of groundwater protection guidelines, a range of additional protocols and standards will be required. These will include protocols for groundwater monitoring including drilling and bore construction, sampling, laboratory testing, data analysis and recording. Other aspects requiring specification would include content of hydrogeological reports, accreditation of groundwater models and possibly even of groundwater professionals.

GROUNDWATER PROTECTION CHALLENGES The protection of groundwater from pollution in Australia presents us with a number of challenges. The first challenge is that presented to governments by the need to develop effective groundwater protection policies and programs around Australia. The AWRC groundwater protection guidelines should assist in that process. Subsequently, governments will be faced with a manpower challenge. In order to implement policy, governments will need to attract and deploy a number of appropriately qualified and experienced professionals in a market where these people are scarce.

Government will also need to address the challenge of community and particularly industry consultation, to sell the policy and overcome the resistance of industry to "talk to the policeman".

Industry is also faced with substantial challenges, firstly to recognise the potential impacts which their operations might have on groundwater and its role as a carrier of contaminants. The impetus for this interest will not be altruism but a keen recognition of the potential financial liability to which they may be exposed if they do contaminate the groundwater. It will also be in the best interest of industry to take a proactive stance with government in the development of protection policy, rather than waiting for the government to arrive at the gate to "help".

Another group with an interest in this matter are the service industries such as consultants, contractors and suppliers of materials to the "groundwater protection industry". Their immediate challenge is to identify and develop opportunities for their goods and services in this new market. The service providers, in particular, need to be proactive and cooperative with government to assist with the implementation of "achievable" policies. The biggest challenge for service providers will be to ensure that the appropriate groundwater protection functions are performed by the service industry.

Another immediate challenge to the industry is the recruitment of professionals. Given the obvious shortage of people, the industry is faced with a substantial education and training challenge. The options include retraining staff, on-the-job training, overseas recruitment, sponsorship of courses and students.

Universities in Australia are constantly being challenged by industry to adapt to the changing market. This is another such case.

Universities will quickly need to decide, h-0pefully in consultation with industry, whether new courses are warranted. The manpower problem is possibly most critical in universities because lecturers in this specialist field are scarce.

CONCLUSIONS The issue of groundwater pollution has long been recognised in Australia, and it is in some localities a serious problem. In the past it has been generally perceived as a problem only in terms of its impact on drinking water supplies or potable groundwaters in general. Contemporary thinking on the issue recognises that this is only the public health dimension to the problem. The role of groundwater in the broader environment, as a source of water for

wetlands and other aquatic ecosystems is also recognised. The significance of groundwater and aquifer storag~space as a component in the long term water resource management of the state is another dimension of the role of groundwater to be considered. The development of a groundwater protection policy must maintain this perspective.

It is recognised that the imperative to protect groundwater in Australia is not as great, in general terms, as it is in some other countries. While Australia draws only a small proportion of its public water supply from groundwater, the USA and Europe rely on groundwater for about 50 per cent of their water supply. While legislation already exists in most states to make acts causing groundwater pollution unlawful, there has been a need for a more proactive approach to prevent pollution rather than just attempt to prosecute the polluter. Some states have developed groundwater protection policies and the recent AWRC study to develop groundwater protection guidelines for Australia will be completed shortly.

The groundwater protection policy framework agreed by the water sector in Australia is founded on the principles of Beneficial Use, Polluter Pays, Risk Assessment and Levels of Action and having a flexible set of groundwater protection guidelines which can be adapted to the institutional framework in each state. This approach should enable each state to appropriately focus and fund protection measures in accordance with the need to protect.

The "groundwater protection industry" including government agencies, "polluting industries", service industries and universities are each presented with a range of challenges by the need to protect groundwater. Meeting these challenges will require additional effort by all parties to get the policy right, make its delivery equitable and efficient; and ensure the development of a sound technological and educational base for the industry in Australia.

ACKNOWLEDGMENTS The author wishes to thank his colleges at Dames & Moore who contributed to the AWRC study team, especially Alan Deeney and John Forth. Thanks are also due to the AWRC Water Resources Management Committee and the members of the water sector in Australia who have assisted in the development of the groundwater protection guideline study.

REFERENCES Australian Water Resources Council 1975, "Groundwater resources of Australia", AGPS, Canberra US Environmental Protection Agency 1987, "DRASTIC - A Standard System for Evaluating Pollution Potential Using Hydrogeologic Settings" by Aller, L. et al USEPA Publn. No. 600/ 2 Le Grande, H. 1983, "A standardised system for evaluating waste-disposal sites", National Water Well Association Groundwater

Australian Water & Wastewater Association "Meeting the Challenge"

14th FEDERAL CONVENTION PERTH, WA 17-22 March 1991 TRADE AND EQUIPMENT EXHIBITION The accompanying Trade and Equipment Exhibition is currently being organised by the Committee. If you are interested in obtaining more information on the Exhibition please contact: Rein Loo Rein Loo & Associates Pty Ltd 457 Beach Road CARINE WA 6020 Secretariat: Tel: (09) 447 6550 AWWA 14th Convention Fax: (09) 448 6997 PO Box 1201 West Perth 6005 WATER June 1990

19

GROUNDWATER CONTAMINATION ASSESSMENT OF GASWORKS SITES

by R.J. PARKER and R.D.A. WOLFE INTRODUCTION Public attitudes and government reaction towards contamination of soil and water are changing rapidly throughout Australia, particularly in Victoria and New South Wales. Media reports relating to contamination of air, surface water, groundwater and soil are now common-place. Much of this attention is now being directed to the problems associated with land that is contaminated with hazardous chemicals. To date, groundwater contamination has been given less attention than contaminated soil and this reflects Australia's limited reliance on groundwater for domestic purposes in most of the major population centres; Perth being an exception.

The consequences of soil and groundwater contamination are generally evaluated with respect to: • health effects and potential hazard to users of the site, and • health and environmental effects external to the site resulting from migration of contaminants.

Since the movement of groundwater provides a significant natural route or pathway for migration of contaminants there is a need to assess the physical and chemical properties of groundwater as part of a general contamination assessment of a site.

There are already many examples throughout Australia where major groundwater studies are now being conducted for contamination assessment and at several locations, clean-up of groundwater is already under way. In general the major concern with groundwater for these studies is the possib!e'down gradient environmental impact rather than direct health risk to consumers of groundwater.

The authors of this paper are currently involved in contamination assessment of several disused gas works sites in Victoria and Western Australia. This paper briefly describes the authors' experience with the following sites: a. West Melbourne Gas Works, Victoria b. East Perth Gas Works, Western Australia.

Residential development is proposed for part of the West Melbourne site and therefore clean-up will need to be to a standard which renders the site safe for future occupants. Assessment of the East Perth site is not constrained by the type of development proposed although the site is within a precinct currently being considered for major redevelopment.

Both sites are beside major rivers. A major component of the East Perth study is to assess the impact of site contamination on the Swan River. For the West Melbourne assessment impact on the river has not been undertaken in detail. The Yarra River is protected under the State Environment Protection Policy which sets river water quality objectives and these objectives must ·be considered in evaluation of possible groundwater contamination at the site.

The paper provides an indication of the nature of the contamin. ants likely to occur on gas works sites and describes the methods of investigations adopted to assess groundwater contamination for the West Melbourne and East Perth Gas Works. The paper concludes by providing a comparison of the sites with particular reference to groundwater.

GAS WORKS WASTE Chemicals Resulting From Gas Manufacture There are three common processes in the manufacture of gas as follows: • Coal carbonisation.

• Water gas and/or carburetted water gas.

• Oil gasification.

The major organic and inorganic wastes likely to result from all of these processes are (Gas Research Institute, 1987): • Organics - coal and oil tars, tar/oil/water emulsions and hydrocarbons sludges.

• Inorganics - coke and ash, spent oxide and lime wastes, sulfur scrubber blowdowns and ammonium sulfate.

20

WATER June 1990

Specific classes of contaminants which result from gas manufacture that are of concern are polynuclear aromatic hydrocarbons (PAH), volatile aromatics, phenolics, inorganic nitrogen, inorganic sulfur and trace metals. Specific chemicals of concern are summarised as Table 1.

Table 1 - Chemicals of Concern in Investigation of Former Gas Works Sites Jnorganics

Metals

Volatile Aromatics

Phenolics

Polynuclear Aromatic

Hydrocarbons

Ammonia Cyanide Nitrate Sulfate Sulfide Thiocyanate

Aluminium Antimony Arsenic Barium Cadmium Chromium Copper Iron Lead Manganese Mercury Nickel Selenium Silver Vanadium Zinc

Benzene Ethyl Benzene Toluene Total Xylenes

Phenol 2-Methylphenol 4-Methylphenol 2,4-Dimethylphenol

Acenaphthene Acenaphthylene Anthracene Benzo(a)amhracene Benzo(a)pyrene Benzo(b)fluoranthene Benzo(g,h,i)perylene Benzo(k)fluoranthene Chrysene Dibenzofuran Fluoranthene Fluorenenapthalene Penanthrene Pyrene 2-Methylnaphthalene

Of these contaminants benzene is a known human carcinogen and a number of the polycyclic aromatic hydrocarbons (PAH) are suspected human carcinogens including benzo(a)pyrene, chrysene and benzo fluoranthene. Contaminants of concern in groundwater include the volatile aromatics, some of the PAH's and phenolics.

Contamination to a lesser extent by metals, ammonia and cyanide must also be considered. ' Approach to Assessment of Contamination Assessment of the extent and 9ature of soil and groundwater contamination relies heavily on the collection and analysis of samples. Extensive field sampling and laboratory analysis is therefore usually required for site characterisation. However, much can be done to limit the amount of investigation by background studies and careful planning of the investigation.

To maximise the efficiency of an investigation for soil and groundwater contamination it is necessary to understand the nature and likely distribution of the contaminants expected to be on the site. For the two gas works sites discussed in this paper collection of background data involved: • examination of historic records and plans held by government departments and in public libraries and examination of aerial photographs • discussions with former operators and staff of the plants • review of the manufacturing processes and the nature of the waste stream • preliminary evaluation of site conditions to enable planning of borehole locations, sampling depths, requirements for groundwater assessment, design of an analytical program and determination of potential hazards likely to be encountered during drilling and sampling.

Information collected during this phase was used to develop a health and safety plan to ensure that site personnel were not exposed to hazardous conditions and a quality assurance plan to ensure that the chemical composition of each sample was disturbed as little as possible during sampling, handling and transport.

WEST MELBOURNE GAS WORKS History The West Melbourne Gas Works occupied a site of 6.8 ha west of the City of Melbourne on the northern bank of the Yarra River.

Operations at the site commenced in 1856 as The City of Melbourne Gas and Coke Company. It was operated by various private companies until 1950 when it was combined with the operations of the

Gas and Fuel Corporation. Initial operation of the site involved production of town gas by coal carbonisation. In 1962 a catalytic oil to gas plant was brought into operation at the site.

Gas production ceased in 1970 and in 1974 the plant was demolished to ground level with in-ground structures being left in place. The site is now occupied by buildings used by Australian Customs, a container storage yard, a major arterial road and grassed areas either side of the road. The site is now being considered for residential redevelopment by the Victorian State Government.

Geological Conditions The site is located on the Yarra River Delta which originally comprised an area of low-lying Quaternary age deposits (parts were originally referred to as the West Melbourne Swamp). Over the years the site and surrounding area has been filled to achieve a ground surface level of around RL 2 to 3 (AHD).

The geological sequence at the site comprises: • Fill - consisting of ash, coke, other gas works waste, rubble and building foundations.

• Coode Island Silt (CIS) - a soft silty clay extending to a depth of around 15 m.

• Fishermens Bend Silt (FBS) - a stiff to very stiff sandy clay.

• Moray Street Gravels (MSG) - sands and gravels interbedded with silts and clays.

• Dargile Formation - variably weathered sandstone and mudstone.

Groundwater beneath the site is encountered in the fill just above the CIS at about RL 1. Flow is generally towards the south-west (ie. towards the Yarra River). The CIS has low vertical permeability with lateral permeability possibly being much higher due to the occurrence of sand lenses.

The MSG is an aquifer with moderately high permeability but has limited use as a groundwater resource due to moderately high salinity.

Investigation Method Initial investigation of the West Melbourne Gas Works involved excavation of 18 test pits and drilling of 26 boreholes ranging in depth generally between 3 and 8 m. One deep borehole was drilled to a depth of about 25 m to investigate potential contamination of groundwater in the MSG. Drilling and sampling methods were selected to minimise cross-contamination between boreholes and sample locations.

To assist with identification of contaminated areas any visual and odorous evidence of contamination was noted for each soil sample. A range of other field tests were adopted including "field head-space tests" and a limited program of shallow gas probe testing using a photoionisation detector. Groundwater monitoring wells were installed at 10 locations within the gas works site or in the vicinity of the site to enable monitoring of groundwater levels and recovery of groundwater samples for chemical analyses. The wells consisted of PVC pipe with a slotted screen at the base. At most of these locations pairs of wells were installed as follows: • One well was constructed so that the slotted length of pipe was installed across the water table to enable sampling of water within the fill and any light non-aqueous phase liquids.

• A second well was constructed so that the slotted length of pipe was installed within the CIS so that groundwater from within the CIS could be sampled.

A monitoring well was also constructed in the deep borehole which was drilled to the MSG. Several seals were installed in the borehole during well construction to minimise risk of crosscontamination between the upper contaminated areas and the MSG. This well was considered necessary since the many hundreds of piles which had been installed on the site were driven to the MSG and the risk of contamination migrating along the sides of the piles down into the MSG was considered to be high.

Results Soil and groundwater samples were subjected to chemical analyses as listed in Table 2. Included in this table are the ranges of concentration obtained for each analyte.

The results of the chemical analyses combined with field results were used to provide preliminary contamination assessment of the site taking account of hazards to future users of the site and 22

WATER June 1990

Table 2 -

Results of Chemical Analysis -

West Melbourne Gas Works

Soil (mg/ kg) Range of Number Values of

Constituent

Groundwater (mg/ L) Range of Number Values of

Results

pH DCM Extractable Matter ('Tar') Total Phenolics Sulfate Ammonia as N Cyanide - free Cyanide - complex Benzene Toluene Xylene Et hyl benzene Oil and Grease Chemical Oxygen Demand Biochemical Oxygen Demand Total Organic Carbon Total PAH

Results

4.2-9.5 160-350,000

124 119

4.4-7.7

<0.03-270 < I0-22,600 <2-2000 <l 0.5-200 <0.01-17 < 0.03-39 <0.03-132 <0.03-73 .1

64 64 29 7 39 29 39 28

0.03-2100

14

0.001-69.7 3-7,400 2-264 <0.2-0.4 <0.2-4.0 <0.01-1 <0.03-l.7 <0.03-938 <0.03-0.7 < 1-890 20-920 <2-200 <34-470 <0.03-15

17 17

Chrysene Benzo (g,h,i) perylene Benzo (a) pyrene Acenaphthene Anthracene Fluoranthene Fluorene Naphthalene Penanthrene Pyrene

0.2-80.l <0.03 0.3-14.8 0.9-7.2 0.6-236 0.3-97 .4 0.3-1 I0.2 0.6-32.9 0.1 -86.6 0.1 -90.3

14 14 14 14· 14 14 14 14 14 14

Chromium Nickel Copper Zinc Arsenic Cadmium Mercury Lead Vanadium Selenium Iron (Soluble)

< 0.2-8.4 l.4-12 0.58-18 0.48-110 0.07-5 .1 <0.1-0.64 < 0.01-0.10 0.48-110 <2-36 <0.01-0.02

22 18 11 8

<0.01-0.11 <0.01-0.21 <0.01-0.07 0.02-0.59 <0.001-0.047 <0.01 <0.001-0.004 <0.01 -0.47

17 17 17 17 17 17 17 17

0.03-2.8

17

IO

5 8 10 16 10 7

17 17 17 17 IO IO

17 13 13 13 17 17 17

environmental effects on the surrounding are;s, Interim acceptance criteria were established for soil and groundwater beneath the site and these were used as a basis for development of a strategy for clean-up of the site. ., The proposed clean-up strategy takes account of the expected residential development of the western part of the site and the expected use of the remainder of the site for road reserve and open space. The proposed strategy for clean-up broadly involves:

Western Side - Residential Development • removal, treatment and disposal of shallow groundwater (ie in the fill and upper parts of the CIS) • excavation of contaminated soil to a nominal depth of about 3 m • off-site treatment of contaminated soil • disposal to landfill of a small proportion of material not amenable to biological treatment • backfilling with clean soil

Eastern Side - Road Reserve and Open Space • partial containment involving perimeter barriers installed into the CIS and surface capping • long term monitoring of groundwater.

The results of the initial studies have indicated that groundwater within the CIS has elevated concentrations of certain constituents.

The consequences of this with respect to the environmental impact on the adjacent Yarra River has not been fully assessed and is the subject of on-going studies.

Further investigations at the site are to be directed towards characterisation of a trial area where samples of contaminated soil and groundwater will be recovered for laboratory treatability studies, field trials and possible trialing by selected contractors.

Various other investigations are required for .more detailed site characterisation and cut-off wall design.

EAST PERTH GAS WORKS History The East Perth Gas Works occupied an area of 6 ha located on the bank of the Swan River upstream from the City of Perth. The

plant was constructed on terraces formed by excavation and filling on the banks of the river. Ground surface level across the site varies between about RL 2 and RL 10 (AHD). The shoreline along the river has been substantially modified by filling activities throughout the life of the gas works. The southern boundary of the site is bounded by a small creek referred to as Claisebrook Drain, the location of which was changed to consolidate the site.

Coal gas was produced at the site between 1922 and 1971 . Coal gas was produced by heating coal in retorts in an oxygen deficient atmosphere and then purifying it to remove ammonia, hydrogen cyanide, hydrogen sulfide, organic sulfur components and tar.

Additional processes included the production of carburetted water gas and producer gas from coke.

Many of the structures used for gas manufacture have now been demolished to ground surface although the rehabilitated purifiers, a petroleum storage tank and various administrative buildings still remain .

Geology

The site is located on the Swan Coastal Plain and abuts the flood plain of the Swan River . The geological sequence beneath the site consists of: • Recent alluvium associated with the Swan River along the eastern boundary of the site.

• Aeolian sands derived from weathering of the Tamala Limestone.

• Guildford Formation consisting of sand, clay and clayey sand layers.

• Kings Park Formation which is early Tertiary age and consists of variably weathered siltstone.

Groundwater flow is controlled by the Swan River to the east and Claisebrook Canal to the south. Groundwater levels on the east and south side of the site are similar to river level at an elevation of about RL 0.5 (AHD) rising to the west. Groundwater levels are expected to fluctuate seasonally and to some extent due to tidal variation.

It is possible that for brief periods, river level may be higher than groundwater level and the flow direction is on to the site.

Investigation Method

Various parts of the site were investigated by Sinclair Knight and Partners at various times up to 1989 (SKP, 1989). The results of this work clearly indicated areas of contamination at the south end of the site. Further work was carried out to provide greater definition of the extent and severity of contamination over the whole of the site. More detailed assessment of groundwater contamination was also necessary to enable evaluation of the impact of site contamination on the Swan River.

An investigation was performed in February of 1990 involving the drilling of 41 boreholes and excavation of 5 test pits. The boreholes were mainly drilled to depths of 5 to 8 m to investigate shallow contamination by gas works waste. As for the West Melbourne site, methods of drilling and sampling were chosen to minimise the risk of introducing contaminants or cross-contaminating samples.

Monitoring wells were constructed in a number of the shallow boreholes to enable water level determination and for sampling of shallow groundwater. ·several deep boreholes were drilled specifically to enable installation of deep groundwater monitoring wells. Where these boreholes were drilled in areas of known or suspected contamination, the upper part of the hole was pre-collared with PVC pipe prior to advancing the hole to full depth . This measure was adopted to minimise the risk of "drag-down" of contaminants during drilling.

Parallel studies are also being conducted to assess the possible effect of migration of gas works waste to the Swan River and Claisebrook Canal, and the impact of past contamination on the river sediments.

Preliminary Results

At the time of preparing this document only preliminary results were available from the field and analytical program of the East Perth Gas Works site. Examination of data for P AH analysis indicated that semi-volatile P AH's constituted a significant percentage of the total P AH's in each of the soil samples analysed from the site. It was therefore proposed for the current study to screen all soil samples for "total volatile P AH" and then select samples of greatest interest for analysis of total and individual PAH.

Preliminary analytical results and field observations from the most recent study indicate the following: • The site is generally underlaid by sand fill and undisturbed sand which in turn is underlaid by interbedded sands and clay.

Comparison of data from different boreholes suggest that the clayey zones are not continuous across the site.

• There was visual or odorous evidence of contamination by gas works waste or petroleum products in many of the shallow boreholes and some of the deep boreholes drilled across the site.

The maximum depth of soil contamination observed in the field was about 14 m.

• Preliminary analytical results indicated significant concentrations of volatile P AH over much of the site. Significant concentrations of toluene, xylene and ethyl benzene have also been observed.

• Preliminary analytical results indicate only localised areas with elevated concentrations of phenolics and only minor elevation in levels of metals. Cyanide has only been observed above detection limit in two samples. Significant concentrations of ammonia and sulfate have been observed.

• Preliminary analytical results for groundwater indicate significant concentrations of phenolics and ammonia.

COMPARISON OF THE TWO SITES Both the West Melbourne and East Perth Gas Works sites are located on the banks of locally significant rivers . Consideration of groundwater as a pathway for migration of contamination is therefore an important consideration at both sites.

The estuary of the Yarra River has mainly been used for port activities and has received industry waste from the initial period of industrial development in Melbourne . The possibility of migration of contaminants to the river therefore may not warrant a high profile. Nevertheless , the Victorian EPA has specific water quality objectives for the estuarine section of the Yarra River and the consequences of contaminant migration from the West Melbourne Gas Works need to be identified. The proposed redevelopment of the Docklands area will also alter the image of the area and public expectations for the quality of river are also likely to change.

At both sites groundwater is an important issue with respect to migration of contaminants and hence impact on the adjacent rivers.

For the East Perth site this was clearly recognised at the outset of the current study and parallel studif!s of the site and the river are being conducted. The issue of groundwater at the West Melbourne site was not specifically addressed in the commissioning of the study. However, in developing the detailed strategy for clean-up of the site it will be necessary to demonstrate that deep groundwater with elevated concentrations of species of concern does not impact on the water quality in the Yarra River.

Comparison of analytical data for the two sites, where available, indicate significantly elevated concentrations in soil for P AH's, volatile aromatics, phenolics (localised at East Perth) and sulfate and elevated concentrations in groundwater of phenolics and sulfate. At both sites there is clear evidence of groundwater contamination from gas works waste.

For the West Melbourne Gas Works the results available to date indicate that contamination is mainly confined to the shallow groundwater, fill and upper part of the CIS, ie. to a depth of 2 to 3 m . The CIS appears to be acting as a barrier to downward migration of contamination. It is therefore expected that cleanup will be largely achieved by jointly treating shallow soil and groundwater. Further evaluation of deep groundwater is nevertheless required to demonstrate that the quality of the deeper groundwater will not significantly impact on the river.

For the East Perth site the preliminary analytical data available for the site indicate contamination at depths of up to more than ten metres. It is therefore unlikely that shallow treatment of soil and groundwater will be sufficient to totally eliminate the occurrence of contaminant migration to the river. Evaluation of the site will be directed at assessing the impact of deep contamination of the river.

REFERENCES Gas Research Institute, 1987, "Management of Manufactured Gas Plant Sites", Document Number GR! 87/ 0260.1 , Chicago Sinclair Knight & Partners, 1989, Interim Report to Landcorp, "East Perth Gasworks Site, Preliminary Evaluation of Site Contamination and lmphcat1ons for Future Redevelopment".

WATER June 1990

23

Environmental Impact of Irrigation Without Adequate Drainage, Kerang Region, Northern Victoria, Australia

by R. C LAKEY -

ABSTRACT Since the 1880s the State of Victoria in south eastern Australia has invested heavily in the construction of water storages, primarily for flood irrigation of pasture on the Riverine Plain in Northern Victoria. The natural surface drainage systems were first utilised for irrigation supply and then, as vast sums were invested in channel construction, they became the drainage lines for effluent disposal. Millions are now being spent on land forming and flood mitigation works with scant consideration for their catchment/ wide hydrologic impact, or the · long term effects on natural surface water systems and their delicately balanced ecologies. Comparatively negligible investment has been made in the development of long term drainage and disposal strategies to cope with the expansion of irrigation systems across the Riverine Plain in any endeavour to achieve balanced resource development.

The disposal of saline drainage water creates a major dilemma in that the primary vehicle for groundwater and surface water discharge from the region and the Murray Darling Basin is the Murray River, which is also relied upon for downstream urban and irrigation supply.

In addition to accepting periodic inflows of surface water, many of these depressions have acted as discharge areas for the local groundwater system during previous periods of high water table conditions. The low watertable gradients, flat topography and the presence of numerous lake systems, some active and some inactive, all point to

At the time of writing, Richard Lakey was Principal in charge of the Melbourne office of Mackie Martin & Associates. He gained his MSc in London in 1976, then worked for the Victorian Government, first in the Mines Department, finally, till 1989, as head of the Salinity Section of the Department of Water Resources. He is actively involved in education in hydrogeology at professional and technical levels and is currently practising as Richard Lakey and Associates. the very fine balance of the system such that relatively minor hydrologic changes can disrupt the equilibrium and lead to quite dramatic changes in the landscape, including the reactivation of inactive (dry) lakes as groundwater discharge zones and widespread land and stream salinisation.

LEGEND Boundwy of K.,•n1 LakH

ArH M•n•e•m.nt '1'6J•ct

SceM of Kllom.lrH

INTRODUCTION The area addressed here (Fig. 1) lies on the Riverine Plain in central northern Victoria, Australia. It extends across the northern-most parts of the Loddon and Avoca River catchments and along part of the tract of the Murray River. The land area predominantly comprises low-lying floodplain sediments and higher undulating lake Junette sediments bordered by Mallee dune deposits along the north western boundary.

The Loddon and Avoca River catchments have been extensively modified by land clearing, road and railway constructions, irrigation and flood mitigation works and more recently by land forming and drainage works. The ongoing cumulative effect of these changes on catchment hydrology has not yet been addressed.

Prior to the commencement of irrigation, water tables in the Kerang Region are thought to have been 6 to 9m below the surface. The introduction of irrigation in the 1880's dramatically increased the water budget. Water tables rose rapidly and pronounced regional groundwater mounds developed beneath the irrigated areas.

Groundwater discharge and evaporitic concentration of salt in near surface soils gave rise to extensive land salinisation and a rapid deterioration in pastures.

The lakes and swamps in the area form a natural terminal lake system for Loddon and Avoca River floodwaters. In the past illdefined drainage paths conveyed outflows from these intermittently filled water bodies to the Little Murray River and Murray River.

24

WATER June 1990

1

DISTRICT

AREA

THE PROJECT AREA ALSO INCLUDES THE WATERWAYS OF THE PYRAMID CREEK, MACORNA CHANNEL, HIRD AND JOHNSON SWAMPS, KOW SWAMP AND THE NATIONAL CHANNEL, THROUGH TO TORRUMBARRY WEIR - NOT SHOWN ON MAP.

Fig. 1 - Kerang Lakes area - management project.

-l

Natural through-flushing terminal lake systems, once intermittently filled by periodic flood flows, have now been converted to permanent lakes. Many natural streams were initially used for carrying irrigation water during the summer months which is contrary to their natural flow regime. When the Loddon River and other streams were allowed to revert to a more natural flow pattern as man made channels assumed the supply role, saline groundwater inflows destroyed much of the bankside vegetation.

Many of these streams are now no more than saline drains with little or no remaining environmental value.

Rising groundwater levels and saline groundwater discharge have transformed previously intermittent wetlands and swamps such as Duck Lake into hypersaline wastelands. The change in hydrologic equilibrium has also transformed temporary wetlands such as Lakes Elizabeth and Wandella into permanent saline basins of internal drainage.

Without a throughflow system these lakes will progressively increase in salinity with an associated reduction in environmental value as their capacity to support flora and fauna diminishes.

However, the waterways within the project area still rank amongst the most important fish habitat areas in Victoria and although extensively degraded, the wetlands of the region are of a very high value on a statewide basis. The area supports a large number of highly valued wetlands within a relatively small geographical area.

The Avoca River appears to have undergone a significant change in hydrology since 1970 and now overflows its terminal lake system far more frequently than in the past.

This phenomenon is considered to be due to the cumulative and combined effects of land use changes and flood mitigation works within the catchment. In recent years there has also been a significant increase in flood frequency and magnitude in the Lower Loddon River. The cause of these apparent changes warrants further research. However, the effect of increased frequency and duration of flooding is prolonged ponding of downstream areas leading to enhanced groundwater recharge, land salinisation and environmental degradation within the Kerang Region.

GEOWGICAL AND HYDROGEOWGICAL FRAMEWORK The Shepparton Formation, consisting of up to 50 metres of mottled clay and silt with thin beds of sand, underlies the area and is locally overlain by Junette and sand dune deposits. A high, saline watertable, continually within capillary reach of the surface, has developed under the majority of the region.

Upward groundwater movement occurs in the lower topographic areas resulting in the formation of saline groundwater discharge areas. Shallow groundwater mounds form beneath the higher topographic areas and irrigated land. Groundwater drains both vertically and laterally from these mounds and discharges into adjacent depressions where evaporitic concentration of salt in the near surface soil leads to land salinisation.

Low lying floodplain areas such as the Sheepwash depressions are particularly susceptible to rapid degradation by this process.

Shallow groundwater salinities throughout the project area are typically in the range of 20 000-40 000 mg/ Lor greater. The only area where shallow groundwater salinities drop below 10 000 mg/ L, except for localised pockets generally associated with channel leakage or lake seepage, is the lyntynder Flats, a relatively well drained area along the Murray River north of Swan Hill.

The lakes and other surface water features throughout the region are artificially maintained at high levels for irrigation supply, storage, evaporative disposal and recreation.

Continuous high lake levels lead to recharge of the underlying and adjacent aquifers and simultaneously prevent groundwater discharge into these natural depressions, resulting in a higher, more saline regional watertable and enhanced salinisation of low lying areas. Evaporation has increasingly become the only significant means of removal of water from the watertable. Salt that would naturally have been periodically flushed from the lakes in floods is now being concentrated in the shallow groundwater system and near surface soils, particularly in topographic depressions.

EXTENT OF LAND, STREAM AND WETLAND SALINISATION The area was recently mapped into five broad land systems. The extent of seriously salinised land was then determined for each land system and is summarised in Table 1.

Table 1. -

Land Degradation

Land System

Lunette/ sand-dune Plains Floodplain: high elevation Floodplain: low elevation Wetlands TOTAL AREA

Area (Ha)

36 8 33 19

800 900 800 200 10 500 109 200

0/o Seriously Salinlsed

5 10 10 40

35

The available soil salinity information suggests a strong correlation between low lying floodplain and high soil salinity. Also evident is a marked correlation between high soil salinity (and sodicity) and highly saline shallow groundwater. Higher floodplain areas adjacent to the Murray River predictably feature lower soil salinities.

Most of the stream systems within the area have been degraded by works intended to upgrade their water carrying capacity including dredging, channelisation and levee banking. Dredging of low lying natural streams has led to the interception of saline groundwater and consequently more saline stream flows.

All wetlands in the project area have undergone major changes since the establishment of irrigation and in most cases, if not all, to their detriment. Major changes have occurred to the water regime, to the water quality and to the vegetation. None of the wetlands could be classified as pristine.

The recent rapid environmental degradation in the Avoca Marshes and along the Sheepwash Creek clearly illustrates that the region has not reached a steady state, but is continuing to degrade under current land and water management practices.

Thentyone out of 40 wetlands in the area have declined in rating since an earlier study in 1975. Increasing salinity has reduced the value of many wetlands for waterbird breed-

ing to the extent t~at some wetlands no longer meet the criteria for listing under the Ramsar Convention.

Those lakes used for storage and supply collect saline river and drain inflows from upbasin during the non irrigation season.

Salinities can reach quite high levels during the non irrigation season and dramatic changes can occur in some areas as saline slugs are flushed through the system during the early part of the following irrigation season. These saline slugs are particularly detrimental to the aquatic environment and high-value horticultural enterprises in the central and north western parts of the area.

Salinity stratification in lakes and streams and the associated deoxygenation of the lower more saline layer can result in a significant loss of habitat and development of potentially toxic conditions for instream fauna. This is of particular importance for the Little Murray River where salinity stratification and severe oxygen depletion have been observed in the weir pool and may also be a significant environmental factor in some of the more saline lakes.

ENVIRONMENTAL IMPACT OF NON INTERVENTION High saline watertables are the fundamental cause of land salinisation, environmental degradation and the loss of agricultural production. Wherever shallow saline watertables persist and the rate of salt accumulation through evaporitic concentration exceeds the rate of salt export via surface and subsurface drainage, salt concentrations in the groundwater system and overlying soil profile will steadily increase. This is considered to be the present situation for ,virtually all the plain and floodplain land systems.

Without drainage the entire lower floodplain area will be seriously salinised and unproductive within thirty years. The 100 year scenario suggests that the higher level floodplain and plain areas will degrade to the point that the level of inputs required to farm these areas will make it uneconomic to do so, leaving the sand dune and lake lunettes, or higher topographic areas as the only productive land systems.

A combination of excessive flooding, high salinity surface water and saline groundwater intrusion will lead to a progressive dieoff of trees and associated vegetation in all areas where they currently occur. Trees, woodland and shrub land will be replaced by more salt tolerant species leading to a low shrubland/grassland of glasswort (bead bush), sea blite, sea barley grass and barb grasses. Only the lunette and sand dune systems will be immune from this process, although it is likely to occur in many interdunal depressions.

Saline surface water and saline groundwater intrusions will lead to progressive deterioration of the remaining river and stream habitat. Wetlands are not in a steady state and will continue to degrade in the absence of periodic flushing and drainage to the point where only two wetland types remain; Permanent Open Freshwater (irrigation supply lakes) and Permanent and Semi Permanent Hypersaline. These wetland categories have the lowest conservation value.

WATER June 1990

25

water discharge from the region, as the processes of salinisation proceed unchecked, has serious long term implications for the Murray River. · The extent to which groundwater tables can be controlled by improved land and water management will ultimately determine the environmental value and productivity of the region. Improved surface and subsurface drainage is by far the most effective means of controlling water tables and provides a base upon which other salinity management techniques can be developed. However, further drainage works should only proceed within a catchment wide drainage strategy, after all upstream and downstream environmental and hydrologic consequences have been carefully considered and evaluated.

Altered catchment hydrology leading to prolonged inundation of downstream areas will continue to cause degradation within the marshes and low lying floodplain areas.

Constant reflooding will progressively result in a change in flora and a reduction in the breeding and carrying capacity of these areas.

The cumulative effects of continued land, stream and wetland salinisation are likely to be serious especially for the Murray River in the case of a major flood which could conceivably break through a number of hypersaline lakes pushing a highly saline slug through the lakes system and ultimately down the Murray River.

CONCLUSION The insidious build up of salt in the groundwater system and soils of the area is the primary cause of environmental degradation. The progressive impact will range from rapid extensive salinisation as has · occurred recently along the Sheepwash depression to gradual almost imperceptible changes in habitat and the diversity of flora and fauna. If adequate drainage is not implemented now, the cumulative impact of increasingly saline groundwater and surface

A 16-person community-based team, the Kerang Lakes Area Working Group, is charged with the very difficult task of formulating a long-term plan for the region.

Their task is exacerbated by the lack of regional drainage strategy, or for that matter, any economically viable and environmentally acceptable means of salt disposal.

Significant environmental rehabilitation could be implemented by selective drainage,

L. DRURY continued from page 15

CONCLUSION The disposal of waste water by aquifer injection is still in its infancy in Australia and only a few examples of this disposal system option is known. An understanding of the regional and local hydrogeological regime into which the water is to be injected is essential. The services of experienced hydrogeologists who have a proven record of such projects is critical. Bore construction should be designed and constructed appropriately based on the aggressiveness and toxicity of the waste water being injected. The recommended physical, chemical and biological criteria outlined in this paper are followed by hydrogeologicals from Coffey Partners International for site evaluation of liquid waste injection.

REFERENCES Bear J., 1972. Dynamics of Fluids in Porous Media. Elsevier, New York, 764 pp. ISBN 0-444-0014-X .

Bear J. , 1979 . Hydraulics of Groundwater. McGraw-Hill, New York, 567 pp. ISBN 0-070-04170-9.

Henry J.L. and Palmer J.R., 1980. Natural and Artificial Recharge of Groundwater in the Callide Valley. Proceedings of the Groundwater Recharge Conference 1980.

Australian Water Resources Council Conference Service No. 3.

Hewitt C.H., 1963. Analytical Techniques for Recognising Water Sensitive Reservoir Rocks. J Pet. Tech. (Aug 1963), pp. 913-18.

·coupled with improved land and water management, ifthis)najor impediment, i.e., ultimate salt disposal, could be overcome.

BIBLIOGRAPHY Anderson, J.R. (1989), The Implications of Salinity Management Initiatives on Fish and Fish Habitat in the Kerang Lakes Management Area, Viet. Dept.

Cons. Forr. & Lands, 106p.

Lakey, R.C. et al. (1986), Riverine P lain Salinity Investigation and Assessment, Viet. Dept. of Ind. Tech . and Res. Sip. Lakey, R.C. (1989), Interaction between Groundwater and Surface Water Systems in the Loddon and Avoca Catchments in northern Victoria, Victorian Dept.

Water Res. publn . (in press).

Lakey, R.C., Lugg, A., Jones, G. (1989), Kerang Lakes Area Management Plan; Environmental Impact of Non-Intervention, Viet. Rural Water Commission, 20p.

Lugg, A . et al. (1989), Conservation Value of the Wetlands in the Kerang Lakes Area, Viet. Dept.

Cons. Forr. & Lands.

Macumber, P.G. (1978a), Hydrologic change in the Loddon Basin: the influence of groundwater dynamics on surface processes, Proc. Roy. Soc. Viet.

90 (1), 125-138.

Macumber, P.G. (1983), Interactions between groundwater and surface systems in nort hern Victoria, unpub l. Ph.D. Thesis University of Melbourne, 506p.

Macumber, P.G. & Fitzpatrick , C. (1987), Salinity in Victoria: Physical Control Options, Victorian Dept.

Water Res. Tech. Rep.No. 15, 50p.

Institution of Engineers, Australia International Hydrology and Water Resources Symposium Perth, Western Australia 2-4 October 1991

Huisman L., 1970. The Hydraulics of Artificial Recharge. In: Proc. Artificial Groundwater Recharge Conference, Reading, UK. Jackes B.R., 1980. Burdekin Artificial Groundwater Recharge Study. Biological Problems in Artificial Recharge of Groundwater. Proceedings of the Groundwater Recharge Conference 1980. Australian Water Resources Council Conference Service No. 3.

Kalish P.J. et al, 1964. The Effect of Bacteria on Sandstone Permeability. J Pet. Tech., Vol. 16, No. 7, pp. 805-814. 1964.

Khilar K.C., 1983. Water Sensitivity of Sandstones. Society of Petroleum Engineers ' Journal. February 1983, pp. 55-64.

Land C.S. and Baptist, 1965. Effect of Hydration of Montmorillonite on the Permeability of Water Sensitive Rocks. J Pet. Tech., October.

Lane W.B. and Zinn P., 1980. Recharge from Weir Storages. Proceedings of the Groundwater Recharge Conference 1980. Australian Water Resources Council Conference Service No. 3. ' Merrick N.P., Ross J.B. and Blair A.H., 1987. The Relative Impact of Three Recharge Sources on the Operation of Sherwood Well field, NSW. Groundwater Recharge Proceedings of the Symposium on Groundwater Recharge, Mandurah, 7-9 July.

Ed . M.L. Sharma.

Mungen N., 1965. Permeability Reduction Due to Changes in pH and Salinity. J Pet. Tech. (Dec 1965), pp. 1449-53.

Olsthoorn T.N ., 1982. The Clogging and Recharge Wells; Report of the Working Group on Recharge Wells. KIWA Communications 72, Rijswijk, Netherlands.

Pearce B.R., 1980. The Use of Temporary Sand Dam Storages in Determining the River Recharge in the Proserpine Area. Proceedings of the Groundwater Recharge Conference 1980. Australian Water Resources Council Conference Service No. 3.

Schippers J.C. and Verdouw J., 1980. The Modified Fouling Index; A Method for Determining the Fouling Characteristics of Water. Desalination, Vol. 32 (1980), pp. 137-148.

Torrey P.O., 1955. Preparation of Water for Injection into Oil Reservoirs. J Pet. Tech.

Vol. 7, No. 4. April 1955.

Van Everdingen R.O. and Freeze R .. , 1971. Subsurface Disposal of Waste in Canada.

Inland Waters Branch, Department of the Environment Tech. Bull. No. 49.

Witherspoon P.A. and Neuman S.P., 1972. Hydrodynamics of Fluid Injection in Underground Waste Management and Environmental Implications. T.D. Cook, ed . Am. Assoc. Petroleum Geologists, Memoir /8, pp. 258-272.

NSW PUBLIC WORKS DEPARTMENT TRADE WASTE SEMINAR GOSFORD 8-9 AUGUST 1990 The Semi nar is organ ised by PWD wi th the co-o perat ion of Gosfo rd City Cou nc il to bring together the key players and stake ho lders to d isc uss and exchange views on the matters of trade waste disposal to sewer in Cou ntry NSW areas.

REGISTRATION FEE $270 (in c ludin g Seminar papers, lunc h a nd official d inner on 8t h August) Information: Ms. M. Kanevsky, PWD Phone (02) 228 5855 Fax (02) 228 5433 26

WATER June 1990

ADVERTISING DISCOUNT Members of AWWA are entitled to a 10% discount for advertising placed direct through Applta Headquarters.

YOUR AWWA MEMBERSHIP WORKING FOR YOU!

Disposal of Residue from Ti02 Production Investigation, Modelling and .Management of Waste Lagoons

by J.E.Bawden, A.C Deeney, R.J. McGowan and P.T. O'Shaughnessy

SUMMARY Approximately 300 tonnes per day of slurried residue from TiO production is discharged into two ponds at Dalyellup. The disposal site is 8km south of Bun bury and is located in an interdunal depression 200m inland from the coast.

The slurry contains about 22% chemically precipitated solids which have low levels of radioactivity and the associated water is brackish with a pH of 8-9.

A field investigation program determined the hydrogeological characteristics of the site and provided data for modelling.

A solute transport model was used to predict the development of the contaminant plume. Two parameters, salinity and 226 Radium, were selected to characterise the mobile constituents of the waste.

Transient solutions obtained from the modelling indicate that waste disposal is likely to have a negligible effect on the confined aquifer.

In the unconfined aquifer, increases in the salinity and the concentration of 226 Radium down gradient of the ponds will probably be less than 100mg/L and 100 Bq/ m 3 respectively.

Management measures include mechanical and chemical processing to maintain consistent waste quality, and regular monitoring of the unconfined and confined aquifers. Changes in moisture content and radioactivity levels within the unsaturated zone beneath the ponds are monitored using neutron and gammaray logging techniques.

INTRODUCTION The Dalyellup disposal site is located about 8km south of Bunbury, Western Australia (Figure 1) in a coastal dune system with a maximum elevation of 45m AHD. The dunes are generally stabilised by vegetation and form a series of ridges parallel to the coastline. Residue in the form of a slurry is being discharged into two disposal lagoons at the base of interdunal depressions which are separated from the ocean by a partially stabilised dune ridge.

The northern and southern lagoons are about 3.2 ha and 4.2 ha respectively.

About 300 tonnes/day of residue is produced at the Kemerton refinery and is transported by road for disposal at the Dalyellup site. The residue contains about 22% chemically precipitated solids which have low levels of radioactivity. The water component of the residue has a salinity of approximately 3000 mg/Land a pH between 7.5 and 9.0 The salinity of the water associated with the residue varies according to the salinity of the refinery process water.

Up to 40 tonnes/day of waste slurry containing about 10 to 20% solids is also transported from the Australind acid neutralisation plant to the Dalyellup disposal site. The slurry is derived from the refinery finishing plant and from a network of groundwater recovery bores. It contains sodium sulfate, iron oxides and pigment. The average loading is therefore about 10m per year, for higher than the natural rainfall and evaporation.

SITE INVESTIGATION AND INSTALLATION OF MONITORING BORE NETWORK An initial hydrogeological investigation of the disposal site was completed in October 1988 to obtain data for an assessment of the potential effects of disposal on the underlying superficial aquifer.

Investigation bores MBl to MB4 were constructed to a maximum depth of 33m along an east-west transect at the disposal site (Figure 1).

Following the completion of the investigation bores, electrical conductivity profiles were run to assess salinity variations with depth.

Groundwater samples from these bores were analysed for major ions, nitrate content and radionuclide activities of Radium (2 26 Ra and 22sRa).

Falling-head (slug) tests were completed in the investigation bores to obtain estimates of hydraulic conductivity and were analysed using the method of Hvorslev (1951).

James Bawden graduated from Environmental Science in 1981, specialising in the dispersion of contaminants during artificial groundwater recharge. After graduation he completed several environmental projects with Mt Newman Mining Co and Mt Goldsworthy Mining Ltd. Between 1983 and 1988 he worked on a PhD in hydrogeochemistry in collaboration with the Perth Urban Water Balance Study. Since joining GRC-Dames & Moore in 1989 he has worked on a variety of contaminant studies and water resource projects.

A Ian Deeney is a Principal Hydrogeologist with GRC-Dames & Moore and is the Managing Principal of their Perth office. He gained an MSc in Hydrogeology and worked in England and Botswana before moving to Australia in 1982. He has been involved in a wide variety of groundwater related projects in WA and overseas whilst employed by the Geological Survey of WA and later by GRC-Dames & Moore.

Bob McGowan received his MSc in Hydrogeology at University College London in 1981. He then worked with the Geological â&#x20AC;˘ Survey of Western Australia on groundwater investigations. He joined GRC-Dames & Moore in 1989 and is a Senior Hydrogeologist, specialising in groundwater development and contamination projects in Australia and overseas. He is the author of the first detailed hydrogeological map to be published for both Western Australia and for the Northern Territory.

Peter O'Shaughnessy graduated in Chemistry and Geology. After eight years with BP Refinery at Kwinana he spent several years farming before joining what was then Laporte Titanium Ltd in 1964. Since then he has been in charge of the Laporte Mining exploration laboratories, the SCM Process Control and Product Assessment laboratories and with the formation of the SCM Environmental Department in 1987 has been their Environmental Manager.

During February and March 1989 a further eight bores (DM series) were constructed at four sites to complete a monitoring network in the superficial aquifer around the disposal lagoons (Figure 1). Two sites are east and upgradient, of the disposal lagoons. At each site, one bore was screened near the water table and a second, deeper bore was completed with an open interval in the basal section of the superficial aquifer.

A production bore (PBl) was constructed in the underlying Yarragadee Formation to supply groundwater for dust suppression and for flushing tankers at the disposal site. PBl is also used to monitor groundwater quality in the Yarragadee Formation.

Shallow piezometers have also been constructed to monitor moisture content and radioactivity in the unsaturated zone beneath the edge of the waste disposal lagoons. Soil samples were taken with a hand auger to a maximum depth of 4.5m at three locations Ul, WATER

June 1990 27

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figure 1

U2 and U3 around the disposal lagoons (Figure 1). The samples were analysed for moisture content, soil moisture chloride concentration and pH. The piezometers were completed with PVC casing to facilitate routine access for gamma-ray emission and neutron attenuation logging. These logging techniques are used to monitor any changes in radioactivity and moisture content of the unsaturated zone beneath the lagoons. Additional lengths of PVC are added to the bores as residue accumulates in the lagoons. Sand bridges have also been constructed to allow easy access to the piezometers.

HYDROGEOWGY Superficial Formations The area is underlain by the superficial formations which extend from the ground surface to about -lOm AHD (refer to Figure 3). The superficial formations form an anisotropic unconfined aquifer comprising sand and limestone with a basal section of less permeable silty sand and sandy clay. The depth to the water table is about 10m beneath the base of the lagoons and varies with topographic elevation.

During October 1988 the water elevation beneath the site was about 1.5m AHD which is probably close to the seasonal maximum elevation. Seasonal fluctuation is estimated to be 0.5m. The superficial aquifer has a saturated thickness of about 10m beneath the disposal site and there is no evidence of laterally extensive zones of low permeability. Consequently, there are unlikely to be significant differences in potentiometric head with depth in the superficial aquifer.

Groundwater flow is westward beneath the disposal site towards the Indian Ocean where discharge occurs across a seawater interface.

Groundwater also discharges by evapotranspiration in a low-lying interdunal area about 500m east of the disposal area. The low-lying interdunal area is subject to inundation during the winter associated with the formation of a perched water table.

Yarragadee Formation The Yarragadee Formation directly underlies the superficial formations in this area and forms a confined multi layered aquifer, comprising interbedded sandstone, siltstone and shale. The potentiometric head in the confined aquifer is about lm higher than in the superficial formations. Consequently there is some potential for upward leakage into the superficial formations. Regional groundwater flow in the Yarragadee Formation is in a northwesterly direction and discharges via the superficial formations into the ocean (Commander, 1984). Beneath the disposal site, the groundwater salinity in the Yarragadee Formation ranges between 600 and 1000 mg/ L TDS.

Groundwater Chemistry and Radionuclide Activity Chemical analyses show that groundwater~ in the superficial formations are mainly of the sodium-chloride type and contain variable proportions of calcium (Ca) and bicarbonate (HCO 3) ions. The higher proportions of Ca and HCO 3 ions are due to tl"ie dissolution of limestone in the superficial formations . The Yarragadee Formation also contains sodium-chloride type groundwater which is not significantly different to samples from the superficial formations.

All baseline radioactivity (2 28 Ra) measurements of groundwater from the superficial formations and from seawater were less than 100 Bg/ m 3, the level recommended in the NHMRC/AWRC (1987) guidelines for drinking water. However, the production bore PBl measures 270 Bg/ m 3, which is significantly higher. Although this baseline level does not represent a hazard, it indicates that such 228 Ra concentrations occur naturally in the Yarragadee Formation.

Unsaturated Zone Chemistry and Radionuclide Activity Following discharge of the slurry into the disposal lagoons, progressive dewatering of the residue is expected to occur as a result of evaporation and to a lesser extent downward leakage. Laboratory tests indicate that the dewatered residue has a very low permeability of about 1 X 105m/ day. Dewatering of the residue will probably result in the formation of a low permeability layer at the base of the ponds which will progressively retard the downward leakage of contaminants.

Runoff derived from rainfall and from ponded process-water can directly infiltrate the superficial formations around the edges of the lagoons. The disposal system is being managed to minimise infiltration around the perimeters of the lagoons.

Laboratory tests indicate that during summer months the residue can dry to about 800Jo solids by weight. However, during winter the residue is expected to retain a higher water content and hence would contain about 40-500Jo solids by weight. During both summer and winter, deep desiccation cracks develop in the surface of the residue as it dries. Slurry from subsequent disposal events infills the cracks. There is minimal release of free-standing water.

At location Ul , samples were taken from the soil profile beneath a 0.5m thickness of dried residue. Measurements from the soil profile at location U2 are representative of an uncontaminated site and provide control data. Soil samples were also taken at location U3 at the edge of the residue in the southern lagoon. Volumetric moisture content, pH and chloride concentration data for the soil profile at location Ul are plotted in Figure 2. The gamma-lay log of this bore, taken shortly after construction, is also shown in Figure 2.

ELEVATION ACCORDING TO GROUND SURFACE (m) + 2 .00

+ 1.00

- - 50mm Diameter ClaH 6 P.V.C. -

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Tailing• Ground Level

-

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1000

3000

4000

5000

1000

7000

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0

20

IO

100

140

GAMMA RADIATION (c .p.a.)

v) - -

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SOIL PROFILE AT LOCATION U 1 BENEATH THE NORTHERN DISPOSAL LAGOON Figure 2

WATER June 1990 29

The pH of all soil samples ranges between 8.2 and 8.9 and there was no significant difference between the pH of soil beneath the control site, U2, and sites Ul and U3 in the disposal lagoons. The soil near the disposal site is naturally alkaline due to its high carbonate mineral content and has a similar pH to the residue. The alkaline pH of the waste and underlying soil profile should ensure that precipitated hydroxides remain in the solid phase and are not leached down to the water table.

In the soil profile at Location Ul (Figure 2) there is a correlation between chloride concentration and gamma-ray intensity. The results indicate that leachate from the residue has penetrated the soil beneath the residue to a depth of about lm. Subsequent gamma logging performed six months after the initial measurements has shown that this peak has not moved down the soil profile but has intensified slightly as residue accumulates in the lagoons.

Routine Jogging of these piezometers with a neutron moisture meter shows that volumetric moisture content periodically exceeds 0.1 which indicates that deep drainage of leachate may be occurring.

Temporal fluctuations in moisture content may be related to alternate disposal (wetting) and drying cycles in each lagoon.

SOLUTE TRANSPORT MODELLING The Dames and Moore TARGET-2DU (Transient Analyser of Reacting Groundwater and Effluent Transport - two-dimensional, cross-section, variably saturated) numerical model was used to predict possible contaminant movement or dispersion beneath the disposal site.

Finite Difference Mesh The modelled area extends from 10m west of the coastline to a distance of 2000m inland. In the vertical direction it extends from an elevation of 16m AHD to - 50m AHD. A finite difference mesh has been superimposed on this area and has been used to represent the boundaries of the model and the different aquifer materials present under the disposal site.

Material lypes Based on the results of the investigation, four layers corresponding to four different aquifer materials were defined. The boundaries between these material types are shown in Figure 3. The aquifer properties selected for each layer are summarised in Table 1. The values of porosity and specific storativity were selected, on the basis of the observed lithologies, from tables published by Freeze and Cherry (1979). The selected values of hydraulic conductivity were based on the observed lithological variation and on the results of the slug tests. Conservative values of hydraulic conductivity were adopted to ensure that model predictions would not be based on an underestimate of the rate of groundwater movement and of the extent of the contaminant plume.

The transport mechanisms incorporated in the model are advection and dispersion, together with density and viscosity effects associated with variable solute concentrations. Both dispersion processes are incorporated, ie mechanical dispersion, and the less important process (in this case) of molecular diffusion. The conservative values selected for longitudinal and transverse dispersivity were based on values for similar sediments obtained from the literature.

o.o

m , AHO

Table I Layer No

Juy Qsfl Qsfu Cpc Kx

Kz Ss P

30

WATER June 1990

Kx

20 10 50 0.01

Kz

Ss

p

0.1 0.1 10.0 0.00001

2.5x10· 6 1.ox10·4 6.25x10· 5 1.ox10·4

0.2 0.2 0.2 0.5

Yarragadee Formation (Sandstone and Shale) Superficial formations (Sand, Clay and Limestone) Superficial formations (Sand and Limestone) Chemically precipitated clay (in disposal pond) Horizontal hydraulic conductivity, m/ day Vertical hydraulic conductivity, m/ day Specific storativity, 1/m Porosity, dimensionless

Boundary Conditions The boundary conditions selected for the computer model are summarised below: Upper Boundary Seawater Interface Prescribed Flux*

Lower Boundary West Boundary Prescribed Headt East Boundary * flow of water and solute in a direction perpendicular to the boundary is zero. t the values of potentiometic head and solute concentration are held constant in each boundary cell.

Two choices were available for simulation of infiltration from the disposal lagoons. (a) Specifying the infiltration rate - which would have been difficult at the time the modelling was done or (b) Specifying a fixed head and allowing the model to determine the infiltration rate based on the other parameters given eg hydraulic conductivity.

Alternative (b) was selected since it was considered that the imposition of a fixed head equivalent to the maximum slurry level, throughout the lifetime of the lagoons, was \jkely to result in greater infiltration than would actually occur in practice with the progressive filling of the lagoons under natural rainfall/evaporation conditions ie a conservative condition was selected.

Infiltration beneath the disposal J,agoons was therefore simulated by a series of cells in which heads are held at this prescribed level.

Steady State Calibration The modelling was completed in two stages, steady state calibration and transient solute transport. Calibration consisted of matching a series of computer generated head distributions to the actual head distribution in the superficial formations, as defined during the hydro geological investigation of the site, and in the Yarragadee Formation (Commander, 1984). Once a satisfactory match had been obtained, simulation of the disposal lagoons was added and the final steady-state head distribution with the lagoons in operation was calculated (Figure 3). There were no significant differences between the head distributions before and after simulation of the lagoons. The final steady-state head distribution was used as the starting condition for all subsequent transient solutions.

Transient Solute Transport Transient solutions were obtained by simulating the infiltration of solute beneath the disposal lagoons and the movement of solute under the influence of steady-state groundwater flow over a period of 5 years.

At this stage, it appears likely that the operational lifetime of the lagoons will be LAYER 4 Cpc, Chemic:aly p,ec,p,lalcd clay (111 Disposal Pond) much less than 5 years. Consequently, the D LAYER 3 • Oslu.(S11nd Supe1ticial lotmahons Lmesione) simulation period extends beyond the operaE3 LAYER 2 Ostt Soperhc<al lotmallOOS tSand Clay & l~nes1ono1 tional lifetime. The need for further modelD LAYERl Juy. Yau aQ&(lee Foimallon Shale) (Sandstone ling will be assessed when 2-3 years monitoring data are available for comparison with the initial model predictions and, 1608.0 if necessary, for re-calibration of the model.

In order to simulate a 'worst case scenario' LAGOON IN OPERATION a number of conservative assumptions were figure 3 made: &

STEADY · STATE HYDRAULIC HEAD DISTRIBUTION WITH

Juy Qsfl Qsfu Cpc

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l 2 3

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• No loss of water would occur from the lagoons as a result of evaporation. In operation, evaporation would cause significant water loss from the lagoons and although the concentration of mobile constituents would increase, volume infiltrating would be lower.

• The layer of chemically precipitated clay derived from the slurry was assumed to be lm thick throughout the simulation period.

The thickness of this layer would in fact increase during the operating period to a maximum of about 6m, thus reducing infiltration rate.

• It has been assumed that the solute does not react with the porous medium through which it is being transported, therefore there would be no attenuation due to absorption or precipitation.

However, clays in the basal sediments of the superficial formations and the Yarragadee Formation are likely to attenuate 226 Ra by cation exchange and adsorption.

• Removal of ions by direct precipitation is likely to be minor because of the very limited reaction between the solute and groundwater.

• Radioactive decay will not produce a significant reduction in the concentration of 226 Ra during the simulation period, because this isotope has a relatively long half-life.

Tuo parameters, (TDS) and 226 Ra, were selected to characterise the effects of the proposed residue disposal. The concentration of these solutes in the lagoons were assumed to remain constant at the following levels during the simulation period.

TDS: 2500 mg/L (2.5 X lQ·3Kg/Kg) 226 Ra: 290 Bq/ m3 (7. 8 X lQ·15 Kg/Kg) Analysis of residue samples taken during the initial period of operations indicate that the actual activity of 226 Ra is much lower (170 Bq/ m3). .

For the transient solutions the initial TDS concentration was assumed to be 1000mg/ L throughout the saturated zone. The hydrogeological investigation showed that TDS in the superficial formations is approximately 1000 mg/L. TDS in the Yarragadee Formation probably ranges between 600 and 1000 mg / L (Commander, 1984) The initial activity of 226 Ra was assumed to be zero for the transient solutions. Data obtained from the monitoring has shown the background radioactivity of 226 Ra in the groundwater to be between 8 and 57 Bq/ m 3 •

The transient solutions for 226 Ra (Figure 4) shows the development of a contaminant plume beneath the lagoon which extends downwards into the Yarragadee Formation. The maximum predicted increase in radioactivity below the water table is less than 10 Bq/ m3 which is equivalent to the lower background levels (8 to 57 Bq/ 3). Significant increases in radioactivity, particularly to the east, are also considered to be unlikely in the longer term.

MONITORING PROGRAMME Groundwater samples are collected on a quarterly basis from all monitoring bores at the disposal site using 12V electric submersible pumps. Samples are analysed for major ion and and nitrate concentrations, gross alpha and gross beta activity, and 226 Ra. The disposal site has been in operation for about 12 months and to date there have been no changes in groundwater chemistry or radionuclide activity which could be attributable to the disposal operation.

Piezometers in the unsaturated zone are also routinely logged with gamma-ray and neutron attenuation detectors. The gamma logs indicate that radionuclides are immobilised in the residue and in the uppermost part of the unsaturated zone extending to a depth of about lm below the base of the residue. Neutron moisture measurements suggest that leachate may be continuing to drain into the unsaturated zone. More recently a deeper piezometer (11m) has been constructed in the southern lagoon to investigate the unsaturated zone down to the water table.

CONCLUSIONS Preliminary solute transport modelling to assess the potential effects of residue disposal on the underlying aquifers suggests that groundwater salinity may increase slightly in the immediate vicinity of the lagoons. The predicted increase in the activity of the radioisotope 226 Ra in groundwater is likely to be small in relation to background radiation levels.

Monitoring of groundwater chemistry and radionuclide activity to date shows that operation of the disposal site has had a negligible effect on the superficial aquifer. Monitoring results from piezometers completed in the unsaturated zone beneath the lagoons show that radionuclides are immobilised in the residue and soil immediately beneath the lagoons. There may be some deeper drainage of leachate in the unsaturated zon~ beneath the lagoons.

To date, gamma-ray logging of piezometers completed in the unsaturated zone beneath the lagoons indicates that radionuclides are immobilised in the residue and soil immediately beneath the lagoons. However, neutron moisture measurements indicate that deeper drainage of leachate in the unsaturated zone may be occurring.

The transient solution for TDS shows the development of a small contaminant plume in the superficial formations beneath the lagoon. This is depicted by a very slight increase in TDS of less than 10 mg/L. The concentration may increase in the longer term, although a significant expansion of the plume, particularly to the east, is considered to be unlikely.

REFERENCES Commander, D.P., 1984. The Bunbury shallow-drilling groundwater investigalion . West Australia Geo!.

Survey Report 12, pp.32-52 .

Freeze, R.A. and Cherry, J.A. , 1979. Groundwater, Prentice Hall Inc. New Jersey, 604pp.

Hvorslev, M.J., 1951. Time lag and soil permeability in groundwater observations. US Army Corps of Engineers, Waterways Experimental Station, Bulletin No. 36.

NHMRC/AWRC, 1987. Guidelines for drinking water quality in Australia. National Health and Medical Research Counci l, Australian Water Resources Council, Australian Government Publishing Service.

m, AHO

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PROJECTED

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!Sand. Clay & Lmes1one1 Juy. Yauagaoee F01ma11on (Sandslorie & Shale)

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" ' Ro CONCENTRATIONS AFTER 5 YEARS OPERATION

figure 4

WATER June 1990

31

WASTE DISPOSAL AND GROUNDWATER MANAGEMENT ISSUES IN JAKARTA, INDONESIA

by P. WHINCUP

ABSTRACT The rapid industrialisation of many south-east Asian countries has brought to the fore the issues of effective and environmentally acceptable waste disposal and water management in these countries. The problems being faced in Jakarta, Indonesia in regard to sea water intrusion, declining water levels and ground subsidence due to poorly controlled groundwater abstraction are described.

The rising concern with domestic and industrial waste disposal and pollution of rivers is also discussed.

Paul Whincup graduated in geology and chemistry from St Andrew's University, Scotland in 1962. He founded Groundwater Resource Consultants in Perth in 1973 and is currently Managing Director of GRC Dames & Moore. In the past three years he has worked in South-F.ast Asia on projects related to environmental audits, waste disposal, water supply and groundwater pollution.

REGIONAL SETTING In South-East Asia, issues of waste disposal and groundwater management are becoming of increasing concern. Whereas historically the quantity of water available was the main consideration, the focus of attention is now being directed towards the quality of water. This, in turn, is often closely related to the efficient treatment and disposal of domestic and industrial wastes.

It is recognised that waste output increases proportionally to growth in GNP. Newly industrialised countries (NICs) such as Taiwan, South Korea and Hong Kong have all achieved annual growth rates of 8 to IO per cent over the last two decades, bringing their per capita garbage..output close to the 1 to 2 kg/ day of developed nations. Hazardous and toxic waste disposal has also increased apace with industrialisation, as has environmental awareness, with the result that these three NI Cs, have collectively committed US$5 billion to control of waste disposal over the next five years.

Indonesia is now witnessing the same process of rapid industrialisation and concern with waste disposal, and although the major emphasis has to be on the rehabilitation of the many heavily polluted surface water sources, it is predicted that protection of groundwater quality will be increasingly addressed. The situation in Indonesia has now changed from that in the recent past, when the need to attract industry often resulted in lax enforcement of environmental regulations and pollution of water resources. The industries themselves are taking steps to minimise water pollution, and many which relocate from overseas to Indonesia are now committed to observing the very strict environmental regulations of their country of origin, wherever they operate.

Control of domestic waste disposal, a major contributor to river pollution, also received considerable attention and formed a large component of the urban development programmes which are underway in the major cities of the country.

Although incineration and composting of domestic wastes have been examined as options, they are too costly for the Indonesian situation and landfill sites are still preferred. The older landfill sites were generally uncontrolled and often sited in aquifer recharge zones. The most recent sites are constructed with basal clay liners, underdrains, leachate collection, stabilisation ponds and methane drainage systems.

Domestic waste in Indonesia contains 75 to 80 per cent organic material, compared to the 25 to 30 per cent of western countries.

There is very effective recycling of salvageable items. It is believed that because of the high organic content of the waste, the very high rainfalls (2.5 to 3.5m/ year generally) and the predominance of volcanic soils, predictions of leachate and gas composition cannot be entirely based on research studies from Australia or other western nations. The groundwater underlying, or in some cases in contact with the landfill, also has different characteristics to those generally encountered in Australia. Because of' the predominance of volcanic sediments, the groundwater chemistry is typified by very low chloride content and high bicarbonate, carbon dioxide and silica concentrations. Little research has so far been done on the nature and extent of groundwater pollution from landfill sites in Indonesia, but because of the generally high population density in close proximity to the landfills, and the common usage of groundwater for domestic supplies, this is clearly a matter which deserves attention.

THE INDONESIAN SITUATION Indonesia, with an estimated 180 million people, has more than ten times the population of Australia in a land area less than that of Western Australia. The majority of the population is concentrated on the island of Java. In the Jabotabek (Jakarta, Bogor, Tangerang and Bekasi) region of West Java alone there are upwards of 20 million people.

There are, as yet, no central hazardous waste treatment or disposal facilities in Indonesia although studies are in progress at Jabotabek and in Surabaya, the capital of East Java.

It is believed that the J abotabek hazwaste TSD (treatment, storage and disposal) facility will be the first constructed in Indonesia.

During the feasibility study for this TSD, protection of groundwater quality at the disposal site has been one of the major concerns in the siting of the facility.

During 1989, the Indonesian press increasingly voiced concerns about pollution of river waters, industrial and domestic waste disposal and water supply. The water supply company in Jakarta found that water purification costs had increased by 40 per cent over the previous year due to increased pollution of the canals and drains which are the main source of supply. Cost of water production in 1989 was 25 cents/cubic metre of which only 15 cents /cubic metre was recoverable from the consumer. A special 'clean rivers project' was commenced in 1989 to investigate pollution of 20 major rivers in the country and the Indonesian Government stated that as from June 1990 they would start suing companies found to be polluting the country's rivers.

32

WATER June 1990

GROUNDWATER IN JAKARTA Historical

Historically, groundwater from springs and dug wells has been an important component of water supply in Indonesia for many centuries. In 1843 the first artesian well was constructed by the Dutch armed forces at Fort Prins Frederik (now the Jatinegara railway station) in Jakarta. This well was only partially successful and it was not until 30 years later, in 1872, that the artesian groundwaters began to be exploited in earnest and used for city water supply.

The population of Jakarta rose from 1 million in the year 1947 to 8 million in 1985 and is projected to be about 14 million in the year 2005. The groundwater demand as a result has increased enormously in the last 100 years.

Scheme Water

Treated surface water is the main water supply source, from springs in the volcanic uplands near Bogor, but deep groundwater also contributes. The estimated domestic water supply demand alone is 1.2 million cubic metres/ day but the water supply company can service less than 40 per cent of the population. Although the company produces IO 500 litres/ sec (about 0.9 million m 3/ day) water losses aggregate about 50 per cent.

As a consequence of the limited capacity of scheme water supply, groundwater is exploited extensively by the majority of households in Jakarta, and by industry. This has led to gross over-exploitation of the aquifer systems with the consequent realisation of a number of adverse impacts.

THE GROUNDWATER SYSTEM The aquifer systems in Jabotabek comprise volcanic sediments originating from the uplands to the south near Bogor. They form an extensive alluvial fan spreading out over the plain and merging in.to deltaic sediments which were laid down under sea water conditions.

The aquifers are a series of thin lenticular and moderately permeable sands extending down to a depth of 250m. Recharge to the deeper aquifer systems occurs in the high rainfall (3.5m annually) volcanic uplands from which the groundwater flows slowly northwards beneath Jakarta and to the sea. The age of these groundwaters near the coast has been determined at 25 000 to 30 000 years. These deeper aquifers, between about 40m and 250m depth, are greatly utilised by industry, to such an extent that artesian heads have declined from 10m above sea level at the turn of this century to as much as 45m below sea level currently. The safe yield of the deeper aquifer systems is estimated to be 3.6m3 / sec but even from the known registered artesian wells, the estimated abstraction is 6.8 m 3/ sec.

The sediments become finer grained and less permeable with increasing depth and because they were laid down under seawater conditions, the remnant salt has been inadequately flushed from the deeper systems so that groundwater salinity increases with depth.

Domestic households almost exclusively use the shallow part of · the groundwater system down to 40m depth. This is recharged directly from infiltrating rainwater and does not rely on recharge from the upland areas. The amount of groundwater available from these shallow aquifers is considerable but the groundwater is heavily polluted by domestic and industrial wastes, and water levels decline markedly in the dry season. All households must therefore boil their water, and generally experience greatly diminished supply in the dry season. Some studies have been made of bacterial pollution of the shallow aquifers, but the extent of heavy metal pollution has not yet been determined.

Artesian wells in Jakarta, by law, have to be registered with the Jakarta Water Supply Company and fees'are charged, based on groundwater consumption. In 1987 there were 2600 registered wells, representing only a fraction of the total number of wells in use.

The Water Supply Company reported that they had written off arrears on artesian water consumption of $1 .7 million for the period 1974 to 1983, and a further $2.6 million in debts was owed for the period 1984 to 1989.

PROBLEM AREAS In Jakarta, there are a number of problems arising from the overexploitation of the deeper aquifers: • Declining water levels are reducing the amount and increasing the cost of groundwater that can be abstracted from the aquifers.

• Salt water intrusion to the aquifers extends several kilometres from the sea, and is predicted to migrate progressively further inland unless the rate of groundwater abstraction can be reduced.

• Land subsidence is occurring in the northern coastal areas of Jakarta resulting in widespread flooding during the wet season.

In 1989 $4.5 million was allocated to raising the height of a 1.2km stretch of road by 0.6m, because of land subsidence.

In the shallower aquifers the widespread pollution from domestic and industrial waste disposal is the major concern.

The problems being faced in Jakarta are not unique in South East Asia. Many other coastal cities with large populations face similar problems (e.g. Bangkok, Manila). The emphasis now is to set up the institutional and legal frameworks for effective control and management of groundwater abstraction and waste disposal.

This is a major undertaking and one which will not be solved in the short term but at least the respective governments have become very much aware of the problems and have now made major commitments in financial and manpower resources to seriously address the problems.

CROSS FLOW TECHNOLOGIES IN WATER TREATMENT

shipping container and can be offered as a skid-mounted unit. Operating the plant is relatively straightforward.

by Chris Fell University of New South Wales

Key issues ,Yet to be resolved include the extent to which entrapment of all particles present in a water will ensure the removal of viruses, organochlorines and possibly heavy metals. High surface area sub-micron particles offer extensive adsorption sites for such entities and their removal may hold the key to successful water treatment.

How successful can the membrane-based technologies of microfiltration and crossflow filtration be in the treatment of water and waste water? This is a question increasingly on the minds of municipal water managers. Research and development in France, Japan and Australia, is suggesting that industrial waste waters and primary sewage can be economically treated by newly available cross-flow microfilters. Problems of removal of troublesome slimes can be addressed by cross flow filtration. Attention is increasingly being paid to the feasibility of using cross flow micro filters also for the disinfection and clarification of drinking water, thus avoiding the chemical uncertainties associated with chlorination. These questions are high on the agenda of topics to be considered at the forthcoming 5th World Filtration Conference to be held in Nice, France, in June of this year.

Key to the resurgence in interest in membrane technologies is a new raft of membrane systems relying on low transmembrane pressures and clever membranes. Low transmembrane pressures mean that much cheaper materials of construction can be used in cartridge fabrication. Energy costs for operating the system are also reduced.

The new generation of membranes feature high open areas and tightly controlled pore sizes. This prevents excessive polarisation of the membrane caused by high concentrations

of retained materials in the neighbourhood of the pores. By increasing pore area and operating under conditions that keep surface concentrations of retained material down, fouling of the membrane is minimised. One Australian company, Memtec Limited, uses periodic gas backflush to clean the membrane. Other producers of membrane equipment rely on back flushing the membrane with filtrate on a regular basis.

The flux that can be obtained in a crossflow microfilter ranges from 0.3-1.0 m3/ m2 hr dependent on the size and concentration of the material being removed. In water disinfection, where the solids burden is low, very high fluxes can _be obtained. This is equally true in the cross-flow filtration of mineral slimes. For the microfiltration of primary sewage the flux is lower, but still sufficiently high to be economical.

Key to the cost structure in processing water by cross-flow filtration is the capital cost of the membrane cartridges and associated plant. The technology is essentially modular with a large plant consisting of an assembly of smaller elements. Current configured plant costs range from $500-1,000 per m 2 of membrane surface, with the cost of the treated water ranging from $0.20/ m3 • The cross-flow technologies are additionally attractive because of their small footprints. A modest sized plant can fit into a

These issues were discussed at a recent Invitation Workshop on Cross Flow Filtration conducted by the Centre for Membrane and Separation 1echnology at the University of New South Wales. The group of 15 from Australia's major industries saw potential for many exciting applications of this new technology.

COAGULANT SURVEY The Australian Centre for Water Treatment and Water Quality Research is undertaking a national study of coagulants and coagulant aids used in potable water treatment. Producers and distributors of relevant products are invited to contact Ms Mary Drikas on (08) 259 0291 for further information.

WATER June 1990

33

WAGGA'S TRADE WASTE MONITORING AND CHARGING PROGRAM

by C: EARNSHAW SYNOPSIS Wagga Wagga City Council has recently adopted a new Industrial and TI-ade Waste to Sewer Policy and the background, underlying principles and objectives are set out.

Council had progressively developed a Trade Waste Policy from an initial simple policy in the 1960's, into the comprehensive Policy today.

This development reflects both the growth and changing nature of the city's industrial base and also the growing awareness of environmental issues and the increasing financial pressure to do more with less.

The paper examines the new policy, particularly the emphasis on a co-operative approach to industry and the user pays principle.

INTRODUCTION What do you do when you discover that a fuel depot has "accidentally" spilt 8000L of petrol into your sewer, or when you discover that an industry, that your Council had actively sought, discharges a waste stream, at a BOD of 5000 mg/ L rather than the 900 mg/ L proposed. What about a developer proposing a Fellmongery, a Chrome Plating Works, or a Cheese Factory?

A review of our Policy and its powers revealed a number of weaknesses in our traditional approach to trade waste control and opened the way for the development of a significant new approach to the question of accepting industrial and trade wastes into sewer.

In NSW at least, the historical approach to Trade Wastes is to ignore or to ban them. Our Local Government Act and Ordinances (By-laws) bans all but domestic wastes from entry into sewer, without specific approval from the Department of Public Works.

In practice this meant ignoring the smaller discharges, banning the undesirables and a painfully long approval process for major industries.

DEVEWPMENTS As we moved through the sixties and seventies a number of large individual industries were connected to sewer, the trade waste charges became a significant source of income and problems started to emerge.

In the eighties we started to deal with a number of very significant industries: • an Abattoir with a daily discharge of 1.5 ML • a Wood Product Factory with a daily discharge of 1.0 ML • a Dairy and Cheese Factory with a daily discharge of around 0.15 ML and occasional discharges of waste cheese product with BODs of around IO 000 mg/L • a Sausage Skin Factory with a very high strength waste and a load equivalent of 5000 ep • a Fellmongery, and • and a Hide Processing Plant.

With the change of scale in industry and discharge came a change in the magnitude of the problems.

THE FLAWS IN OUR TRADITIONAL APPROACH 1. This traditional approach was forcing Council into a policing role, resulti11g in a great deal of our scarce resources being diverted to and wasted on policing.

2. The legal back up and penalties available to us were pitifully inadequate. The NSW Local Government Act provides for a penalty of $1000 for non-compliance. When a major conflict developed Council couldn't match the resources of the multinational companies we were dealing with.

3. Our charges, while being adequate to cover the cost of treatment, weren't anywhere near the individual industries' cost to provide proper pretreatment and consequently tended to encourage overstrength discharges.

This paper was presented to the 1989 Engineer's and Operator's Conference.

38

WATER June 1990

Colin Earnshaw is the Facilities Engineer with Wagga Wagga City Council, a position held for the last eight years. Prior to that he had the positions of Shire Engineer with the Shires ofKyeamba and Central Darling and worked for the consultants McIntyre and Associates in North Queensland and the State Electricity Commission of Victoria.

4. The policy really didn't deal with the question of what to do when an industry failed to comply. We could always disconnect, but have you ever threatened to close a factory? Particularly ones employing over 500 people, owned by a multinational and during a local campaign to attract industry to town? That isn't good politics.

THE NEW PHIWSOPHY In considering our situation and developing a new approach a number of basic philosophies emerged and were followed.

• Total consistency with Council's evolving Corporate Plan.

• A commitment to protect the integrity and safety of the sewer system.

• Adoption of the Polluter Pays Principle.

• That Council would, as far as practical, attempt to have a cooperative approach to waste management. Involving the Industry, making them responsible for quality but offering our resources to assist. Sharing the responsibility for 'monitoring and testing and ensuring that the factory manager sees Council as a colleague rather than the enemy.

• Utilisation of financial rather Plan legal incentives to ensure compliance. Our experience is that if you can worry an accountant you will get action.

• Recognition that we needed to move towards a statewide approach in dealing with waste generators. There were a number of reasons for this:- (1) The fact that developers are shopping around for the "best" deal (this is often translated into the weakest policy.

(2) The need for developers to be able to see the real benefits of decentralisation and (3) The need to have an organisation larger than Council to set the legal precedents.

• Recognition of other parts of Council's overall sewer policy, particularly those relating to nutrient removal and effluent reuse.

The Policy developed, follows as closely as possible, that developed by the Sydney Water Board.

The principle elements of the Policy are: Discharge Categories Waste sources are divided into four distinct categories based on volume and strength.

Service Agreements Approval is in the form of a signed legal document. This document is fundamental to Council's ability to take legal action for non-compliance which ultimately would take the form of breach of contract.

The agreement is in two parts: a legal agreement between the discharging company and Council and a number of schedules covering the details of the waste stream, the basis of testing and of charging and details of the process, pretreatment equipment etc.

Also included are conditions requiring the licensee to co-operate with Council and to advise of any changes in discharge of process.

A fee is charged for major industries.

Inspection and Monitoring Quantity of flow is based on an agreed percentage of the metered water supply to the site or if the applicant doesn't agree with this, on readings from an approved meter provided by him.

Quality. The applicant has to provide sufficient test data to establish a pollution profile and be the basis of charging. Council only does occasional check tests at its cost.

In the event of a site not satisfying an inspection requirement or the waste stream being out of the limits expected from the pollution profile then the applicant has to pay for additional v_isits and testing until performance is again in accordance with the agreement.

Charges Charges are made for each individual component of the waste stream, and vary according to the strength of that pollutant.

Volumetric charges are calculated on the flow for the accounting period and then discounted by the amount already paid as rates for the same period. This effectively means that the sewer rate buys the industry a discharge entitlement.

At a BOD of 400 mg/ L 18.3 cents At a BOD of 800 mg/ L 25 cents At a BOD of 1600 mg/ L 34.5 cents At a BOD of 3200 mg/ L 47.5 cents At a BOD of 6400 mg/ L 65.3 cents At a BOD of 13200 mg/ L 90.2 cents As can be seen this has the effect of being self regulating . The industry accountants seem to have even more interest than we do in controlling waste stream strengths.

Sewer Admission Standards The usual list of upper limits on individual pollutants. The one difference being that Category four discharge allows for wastes with strengths above these limits .

Notes These apply to the admission standards.

In the past three of the main areas of concern have always been associated with • Over-strength wastes .

CONFERENCE CALENDAR

1990 5-11 August, Hamburg, FRG 7th International Congress on Pesticide Chemistry 8-9 August Gosford, NSW Trade Waste Seminar Mid-August, Cambridge, USA Physical Models for Transport and Dispersion 12-15 August, Phoenix, Arizona, USA Conserv 90 - AWWA/AWRA/ASCE/ NWA Water Supply Solutions for the 90s 13-16 August, Townsville, Qld Environmental Analytical Techniques Estuarine and Coastal Lagoon Water Quality 20-24 August, Vancouver, Canada Solid Waste Management 20-24 August, Netherlands Remote Sensing and Water Resources 27-31 August, Vin del Mar, Chile Water Quality - Microbiological Aspects September, Porto Alegre, Brazil Groundwater Pollution - Control and Prevention 6-8 September, Silsoe, Bedford, UK Monitoring, Maintenance and Rehabitation of Water Supply Boreholes and Irrigation Tubewells 9-12 September, Portland, Ore, USA Distribution System 10-11 September, Glasgow, UK 4th Annual IWEM Conference and Exhibition 10-14 September, Amsterdam, Netherlands Netherlands Water Quality Management in Seas of Restricted Circulation 10-14 September, Netherlands North Sea Pollution - Strategies for improvement 11-13 September, Amsterdam, Netherlands Water Supply Improvement through ICA In conjunction with Aquatech 90 11-14 September, Belgrade, Yugoslavia IAHR 15th Symposium 16-21 September, Brazil Pollution Protection and Control of Groundwater 18-20 September, Wallingford, UK River Flood Hydraulics 24-26 September, Anaheim, Ca, USA NWWA Convention and Exposition 24-28 September, Cambridge, UK International Conference on Use of Constructed Wetlands in Water Pollution Control

• Occasional rogue discharges of very..strong wastes, and • Difficulties in ensuring that grease traps, fat and oil arresters were cleaned .

Under the new policy these are dealt with almost automatically as follows : An industry that discharges over-strength wastes fails its inspection and consequently has to pay for further testing and inspection. They also pay for their waste stream at a higher unit rate .

In the case of the rogue discharge, the discovery of any over strength discharge affects the unit rate for the entire accounting period plus introducing the other penalty provisions. Industry can't afford this and it becomes attractive to negotiate the discharge of that sort of waste as a one-off discharge.

Failure to clean grease traps automatically changes the category of discharge and unit charge rates .

CONCLUSION Wagga Wagga City Council has moved a step further down the path of dealing with Industrial and Trade wastes . The co-operative approach seems to be appreciated by industry and indeed the higher charges that are resulting from the new policy seem to be well accepted as the industry can see what they are "buying" and how they can lower this charge if they wish to.

ACKNOWLEDGMENT The author records his thanks to the people in the industry who collected information and developed an understanding of the issues involved and to the City Engineer and Council for their support in the preparation of this paper.

October, Spain Advances in Anaerobic Treatment 1-3 October, Madrid, Spain 4th International Gothenburg Symposium on Chemical Treatment 7-11 October, Dubai, United Arab Emirates Arab Water Technology Exhibition 17-20 October, Brisbane Water and Energy Conservation in Commercial Buildings 29 October & 1 November, Canberra IE Aust. Electric Energy Conference 90 11-15 November, San Diego, California, USA Water Quality Technology Conference, 20-21 November, Nicosia, Cyprus IAWPRC International Specialised Conference on Industrial Waste Water Treatment and Disposal 17-18 December, Chicago, lllinois, USA Agricultural and Food Processing Wastes

1991 3-8 March, USA Off-flavours in the Aquatic Environment 17-22 March, Perth, WA AWWA 14th Federal Convention 3-5 April, Lisbon, Portugal IAWPRC - Marine Disposal Systems 7-11 April, IE Aust.

National Engineering Conference Development and the Environment 15-20 April, Malta Desalination and Water Reuse 13-18 May, Rabat, Morocco 7th IWRA World Congress on Water Resources - Water for suitable development in 21st century June, Vienna, Austria 17th International Congress on Large Dams 3-6 June, Durham, New Hampshire, USA IAWPRC - Watermatex '91 Systems Analysis in Water Quality Management and Clinic on Simulation of Environmental Processes 9-15 June, Frankfurt, West Germany AHCEMA '91 23-27 June, Philadelphia, Pa, USA AWWA Annual Conference 8-11 September, Atlanta, Ga, USA Distribution System Symposium 9-13 September, Madrid, Spain 24th IAHR Biennial Congress 2-4 October, Perth International Hydrology & Water Resources 21-23 October, Washington DC, USA NWWA National Conventional and Exposition

WATER June 1990 39