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AUGUST 1988 JOURNAL OF THE AUSTRALIAN WATER AND WASTEWATER ASSOCIATION

Western Australian Issue SLUDGE MANAGEMENT TO YIELD OIL RECYCLING IN RESOURCE INDUSTRIES RESTRUCTURING A MAJOR AUTHORITY - LESSONS LEARNED PEEL INLET-HARVEY ESTUARY MANAGEMENT ASSET REPLACEMENT IN THE FUTURE ASSET MANAGEMENT - NSW SEMINAR


EXECUTIVE DIRECTOR P. Hughes P.O . Box A232 Sydney South 2000 (02) 269 6814

FEDERAL PRESIDENT M. Dureau , P.O. Box 152, North Ryde 2113 (02) 887 2555.

FEDERAL ~: CRETARY G. Cawston Box A232 P.O. Sydney St h., 2000. (02) 522 1148

FEDERAL TREASURER J . D. Mol loy, Cl- M.M.B.W. G.P.O. Bo x 4342, Melbou rn e 300 1, (03) 615 599 1

BRANCH SECRETAR IES Canbe rra, A.C.T. M. Sh;,rpin , Wil l ing & Part. , P.O. Box 170, Curt in, A.C.T. 2605. (062)81581 1

New South Wales Mrs S. Tonkin-Hill , Sinclair Knight & Part. 1 Chandos St., St. Le onard s, 2065, (02) 436 7166

Victoria

water

ISSN 0310- 0367

Official Journal

AUSTRALIAN WATER AND WASTEWATER ASSOCIATION

Vol. 15, No. 3, August 1988

CONTENTS My Point of View-Robert Humphreys ..... ... .... .. ... ......... .

5

Association and Industry -

News ............ .... ... . .... .. .... .

6

Book Review . . ........... ... . .. ............................. .

12

Haz Waste Update -Errol Samuel . . .............. ......... ........... . ... .. .

13

IA WPRC News . . . . ... . .................. . .... . . .... ......... .

14

Lessons from Restructuring a Major Authority -Keith Cadee ......... ... ....... . ....... .... .. . . ... . ... .

16

NSW Seminar: Manage Assets Today-for Tomorrow -John Schlafrig ... . ....................... .. ........... .

20

Water Recycling in Resources Industries -Allen J. Gale ............. .. .................. ......... .

22

Conference • Courses • Workshops ........... . ....... .. . ..... . .

26

J . Park , Water Training Ce nt re , P.O . Box 409, Werribee, 3030. (03) 741 5844

Queensland D. Mackay, P.O . Box 41 2, West End 4102 . (07) 844 3766)

South Australia R. Townsend , State Water Laboratorie s, E. & W.S. Priva te Mail Bag , Salisbury , 5108. (08) 259 0244

Western Au stralia Mr K. Cadee, Wat er Auth. of W.A. , P.O. Box 356, West Perth 6005 (09) 420 2457

Tasman ia A. B. Denne P.O. Bo x 78A, Hobart 7001

Asset Replacement in the Future -W. David Woodhead and S. N. Tucker

1

25

Northern Territory P. Abbey, P.O. Box 37283 Winnellie, N.T. 5789. (089) 89 7290

EDITORIAL & SUBSCRIPTION CORRESPONDENCE G. R. Goffin , 7 Mossman Dr., Eag lemont 3084 03 459 4346

ADVERTISING Ann Sykes Appita 191 Royal Parade , Parkville 3052 03 347 2377

Oil From Sludge: A Cost Effective Sludge Management System - T. R. Bridle and C. K. Hertle

32

Calendar .. . .. . .. ..... . . . .. ....... . . ......... . . ............. .

38

The Peel Inlet and Harvey Estuary Management Strategy -R. A. Gorham, R. Humphries, J. S. Yeates, G. R. Puglisi and S. J. Robinson ... .......... . ............ .

39

New Products ........... .... .. .. . ....... . ... ................ .

45

COVER PICTURE The one tonne per day Oil-From -Sludge Demonstration Plant, currently operating at the Water Authority of Western Australia's Subiaco Wastewater Treatment Plant in Perth. This novel sludge management technique produces about 300 litres of oil per tonne of sludge processed. Details on this technology are described in the paper on Page 32 of this issue. Front cover donated by Campbell Environmental Limited

The sta tement s made or opinions expre ssed in 'Water ' do not necessarily re flect the views of the Australian Water and Wastewa ter Association, its Council or committees.

WATER Augusl, 1988

I


Lessons from Restructuring · of a Major Water Authority Keith Cadee SUMMARY The Water A uthority of Western A ustralia was for med on July 1, 1985 by the merger of the Metro politan Water Authority and the water related activities of the Public Works Department of WA. As part of the merger process, significant restructuring of the non operational areas of the Authority occurred. Restru cturing of the operational areas occurred with regionalisation on July 1, 1987. As part of the regionalisation process, salaried staff numbers were reduced by 80Jo compared with the pre-regionalised organisation . Further redu ctions in employee numbers are anticipated and a reduction in numbers of 200Jo over five years has · been adopted as a target. Details of the restructuring processes are described and the problems and lessons learnt are discussed .

BACKGROUND Prior to the formation of the Wa te r Authority of WA (WA WA), water, sewerage , drainage and irrigation services throu ghout WA were met by six different groups. • The Metropolitan Water A uthority (M WA) - provided water supply, sewerage and main drainage services to the Perth metropolitan area. • The Public Works Depart ment of WA (PWD) - provided water supply, sewerage , main drainage and irrigation services througho ut the non-metropolitan areas of WA. • Country Water Boards - provided water supply in the towns of Bun bury, Harvey and Busselton . • Local Government - provided minor drainage and some sewerage and water supply throughou t WA. • Company Towns - various privately owned and operated water supply, sewerage and drainage schemes existed in WA, mainly associated with the mineral industry. • Individuals - some individuals were responsible for their own wastewater disposal and water supply. The Water Authority of WA was formed on J uly 1, 1985 by the merger of the Metropolitan Water A uthority and the water related activities of the Public Works Department of WA. Altho ugh the Water Authority of WA is not the sole provider of water related services, it does serve at least 970Jo of all Western Australians in so me form or another.

MERGER OF MW A & PWD The merger of the Metropolitan Water Authorit y (MW A) and the P ublic Works Department of WA (PWD) was an election c;ommitment of the Burke Labor Government elected in March 1983. T he reasons for the merger were (i) To achieve uniform policies and level of service throughout WA . (ii) To remove areas of duplication between the two agencies .

(iii) To achieve economies of scale. (iv) To manage the State's water resources in an integrated manner. and fifthly a reason not given at the time of the merger b ut which has subsequently become necessary du e to the financial stringe ncies applied to the Auth ority. (v) To provide a means for cross subsidisation of country customers by metropolitan customers to reduce or eliminate the subsid y provided the State Treas ury for country operations. T he merge r was achieved on July 1, 1985 after a planning and implementation phase of 18 months. In hindsight the period between the decision to merge and the actual merger was undesirably

Th is paper was presented by Mr Cadee at the A WWA Summer School in Hobart, Feb ruary 1988. 16

WATER Augus1, 1988

Keith Cadee is Supervising Engineer with the Water Authority of Western A ustralia in Perth. Keith has been with the Water A uthority fo r 12 years during_ which time he has had extensive experience with the investigation, design and operation of wastewater treatment and disposal fa cilities.

A. Keith Cadee

long. It may not have been possible to achieve the result any quicker but in the months prior to merger there was a fa ll-off in performance due to uncertainties and the need to commit resources to the merger process rather than the maintenance of the two ongoing agencies. The philosophy of the merger was to join the two Authorities into one workable A uthority with the minimum possible disruption to the existing operations. It was a deliberate policy to restructure only to the minimum extent necessary and th e need fo r a major reorganisation after one or two yea rs was recognised at the time of the merge r. In view of the desire to keep the changes as small as possible it is interesting to reflect on how much change actually occurred in unifying the non-operational areas of the A uthority. The areas of Water Resources, Design, Supply, Finance, Customer Acco unting and Management Services were integrated at the time of the merger. All these groups required quite new structures and new personnel to serve the needs of the new A uthori ty. Not surprisingly it took many months for some of the groups to become established and provide the pre-merger levels of service to the operating branches.

POST-MERGER The period following the merger was quite difficult for the newly established areas of Finance, Supply and Management Services . Some of these branches were providing completely new servi ces which did not previously exist within the Authority (such as Supply) while others had undergone major restructuring as part of the merger. T he most serious post-merger problem was with the computerised financ ial system. A new system was commissioned at the time of the merger while the tw o systems previously operated by the MWA and PWD were not maintained. The situation became quite serious in the first few months after merger as the feeder system became choked with paper . This was not helped by the unrealistic expectations of the new systems which had been created in the operating Branches. T he deficiencies in the computerised fin ancial systems were so severe that they were never satisfactorily resolved and the system was rebuilt as part of the regionalisation exercise two years later. T he problems with the computerised finan cial system demonstrate how essential are careful implementation , training and maintenance of existing systems in parallel during commissioning to the success ful implem entation of computerised systems of this type. While there was a strong desire by the Support Branches to provide better, more efficient services to the Operating Branches, there were understandable difficulties and delays while new Branches were established and new procedures developed. This created friction with the Operating Branches which were largely un changed by the merger and were understandab ly anxious for their Branches to conti nue to operate at pre-merger levels of efficiency and effectiveness . This friction persisted for a very long time.


Within the Country Operating Branches there was considerable expectation of rapid change immediately following the merger. This was probably due to the absence of restructuring in the country areas as part of the merger process·. The last major restructuP ing of Country Operations was in 1975 . The situation in Perth was somewhat different as most of the Operating Branches had undergone major reorganisations over the three or four years prior to the merger. Therefore, there was not a strong desire for further rapid restructuring within the Metropolitan Operating Branches. In general, those Branches desired to consolidate the improvements in efficiency and productivity achieved as a result of their recently introduced structures and work practices. The strong push for change in the Country was reflected in the formation of South West and North Regions on July 1 1986. Both these regions were established prior to formal consideration of regionalisation for the State as a whole. There were good reasons at the time for the early establishment of these Regions, reasons which were a combination of local issues, Government policy and the retirement of several Senior Engineers creating the opportunity to form Regional Manager positions from these Engineering positions. The early (even premature) formation of these regions and the structures adopted effectively defined the broad structure of a regionalised Water Authority. Although regionalisation of the entire operations of the Authority had not been formally adopted at the time of the formation of the first two regions, any subsequent commitment to total regionalisation had to accommodate these Regions as operating realities which were unlikely to be radically altered.

REGIONALISATION Reasons for Regionalisation Regionalisation of the Water Authority had been the policy of the Board and the Government for some time prior to the decision to forma lly commence the regionalisation process. The reasons for regionalisation were: • To implement the Government Policy of Decentralisation and the development of regional centres. • To improve efficiency and effectiveness by radically decentralising the operations of the Authority. A target reduction of 20% in the number of employees over five years was seen as achievable with a regionalised structure. • To provide a uniform structure within the Authority enabling career paths to flow smoothly from the Country back to Perth.

Scope and Timetable Early in May 1986 a small Regionalisation Task Force was formed to study in detail how regionalisation of the entire Water Authority could be achieved. The Task Force was required to: (a) Identify a number of conceptual options for the regionalisation of the entire Authority. This task was completed by August 31, 1986. (b) Following the selection of the preferred option, develop in detail (i) Regional boundaries. (ii) Regional centres for regions. (iii) Conceptual organisational structures for the entire Authority. This task was to be completed by December 3 I, 1986 so that the regionalised Water Authority could be operational by July 1, 1987.

Identification of Issues In developing the options for regionalisation, the Task Force consulted widely with the Authority's employees and the views of the Unions were sought. However no positive contributions were obtained from the Unions. As part of the consultation process 281 people from the middle management level throughout the water Authority were consulted. In addition, 92 written submissions were received. The key issues raised by the Authority's middle managers were as follows. The issues are in approximate decending order of priority (as seen by them).

ISSUE

COUNTRY METROPOLITAN P'ItIORITY PRIORITY

1. Career Pathing 2. Delegation 3. Conditions of Country Service

(particularly housing) 4. Maintenance of Expertise 5. Cost Justification of Regionalisation

6. Location Regional Boundaries and Regional Centres 7. Policy Co-ordination 8. Form of Metropolitan Regionalisation 9. Haste of Regionalisation 10. Communication & Information Technology 11 . Autonomy of Regions 12. Customer Service 13 . Reorgan isation 14. Personnel Policies

2 1

3 7

3 10

2 1

6

6

4 7

12 4

13 12

7 7

7 5 7

9

11

13

JO 10 12

Communication In addition to consultation with staff, two bulletins and discussion papers were prepared and circulated widely within the Authority to inform staff as much as possible of what the task force was doing . Although these were useful means of keeping the staff informed, they were not completely satisfactory because only options and issues were being identified and little 'concrete' information cou ld be made available to staff.

Preferred Option The preferred option consisted of eight operating regions (two Perth Regions and six Country Regions) a Headworks and Treatment Branch for Perth and six central support groups. The structure of the reorganised Authority is shown on Figure 1.

Lessons from the Regionalisation Process (i) A major outcome of regionalisation was an initial reduction in salaried staff numbers of 80Jo compated with the pre-regionalised organisation. This was achieved mainly by natural wastage but a targeted redundancy scheme also encouraged a significant number of senior personnel to retire. (ii) An important element in the success of regionalising the Authority was the offering of a targeted redundancy scheme to selected personnel prior to filling any positions in the regionalised structure . This allowed the implementation to be much less traumatic than would have otherwise been the case had all positions first been filled then a redundancy scheme offered to those who did not secure a position. (iii) In late 1986 the Public Service Board introduced a Broadbanding system to reduce the multitude of salary levels to just nine classification levels with a total of only 43 salary increments over the entire range of classifications. The introduction of Broadbanding was exteremely important for the smooth implementation of regionalisation. It simplified the classification of new positions within the Authority and enabled much greater flexibility in the movement of staff between different areas within the Authority. (iv) To fi ll the 1842 salaried positions in the regionalised structure within the four months allowed by the timetable, many of the normal Public Service Board (PSB) procedures were bypassed. Most of the responsibilities normally the province of the PSB were delegated to the Water Authority. An officer from the PSB was seconded to the Water Authority during this time to ensure compliance with PSB policies and his presence was vital to the successful filling of the large number of positions in such a short period of time. Certain provisions of the Industrial Relations Act relating to appeals were also suspended during this time and internal procedures for review and appeals were set up in their place. Initially all new positions which could not be filled by like-to-like transfers were advertised within the Water Authority and only if no suitable applicants existed within the Water Authority were positions more widely advertised. (v) An important factor in the rapid introduction of regionalisation was its acceptance by most of the staff. There were few who WATER August, 1988

17


. WATER AUTHORITY OF W.A. DIRECTORATES AND BRANCHES MANAGING DIRECTOR MANAGEMENT SERVICES

• Fl NANCIAL SERVICES

• INFORMATION TECHNOLOGY • SUPPLY SERVICES 0

·i~EJS~t~NG PERSONNEL SERVICES • FINANCIAL • ADMINISTRATIVE SERVICES PLANNING •INDUSTRIAL RELATIONS • MANAGEMENT ACCOUNTING

- - --

ENGINEERING SERVICES

REGIONAL SERVICES

• HEADWORKS & TREATMENT • PERTH NORTH • PERTH SOUTH •SOUTH WEST •NORTHWEST •MID WEST •CENTRAL GOLDFIELDS 0 GREAT SOUTHERN

- - C ORPORATE SUPPORT WATER RE SOURCES

• WATER RESOURCES • ASSET •WATER SUPPLY MANAGEME NT DESIGN PLANNING •SCIENTIF IC •WASTEWATER & •G ROUNDWATER SERVICE S DRAINAGE DESIGN ·suR FA[ EWATER 0 0 ·REGIONAL ELECTR ICAL & DR ILLING & TESTING ENG INEERING MECHANICAL DESIGN SUPPORT MAJOR PROJECTS • VEHICLE & •URBAN 0

~~~~EMENT ~flloL~PMENT

0

0

TECHNOLOGY •SURVEYING & TRANS FER & MAPPING TECH NICAL AUDI T

Figure 1. Structure of the reorganised Authority.

lost from the restructuring and a large fraction of the staff achieved promotions and or improved job opportunities from the new structure.

ISSUES FOR THE FUTURE (i) Regionalisation is not seen as the end to restructuring within the Water Authority . The next step anticipated is the devolution of responsibilities currently met by central support groups to the Regions. The nature and scope of this transfer of responsibilities is currently under review. (ii) Implicit in the regionalised structure is the delegation of authority to the Regions for many of their own activities. For the potential benefits of regionalisation to accrue, delegation downward within Regions must also occur. (iii) Multiskilling is seen as a means of achieving reductions in numbers and increased efficiency. Many examples of multiskilling for salaried staff were introduced as part of the regionalisation process. One problem with this approach is the potential for the loss of expertise within the Authority and the inability of Engineers in particular, to properly train and develop the staff under their control in technologies which are largely unique to the Water Industry. To avoid this problem, different regions have been designated as Centres of Expertise for various activities . These centres have the responsibility for maintaining and developing expertise in their field and transferring it to other regions. As pressures increase in future years for more reductions in staff numbers it will be important that the Centres of Expertise not be sacrificed for short-term gains in staff reductions. · (iv) Greater multiskilling of non-salaried employees must also occur in the future if target productivity improvements are to be realised . This will require some changes to occur in the approach by Unions to this subject. (v) There are strong local forces which resist the closure of offices, depots etc and reductions in numbers of employees in country towns. If the new structure achieves the improved efficiency planned, many creative solutions will need to be found in some country centres . The devolution of more responsibilities to the Regions and the consequent transfer of staff may be a means of balancing numbers in some areas. (vi) The various Regions operate with a high degree of autonomy . It is therefore important that systems exist to ensure uniform 18

WATER A ugusr, 1988

policies and practices within the Authority. The Technology Transfer and Audi t Branch was established to ensure uniformity. Much greater access to modern information technology is also essential and the Authori ty has already made a significant commitment in this area. (vii) An important issue for the Authority , in a period of reducing resources and numbers, is to ensu~e that our assets are not run down. It is very easy to make large sho rt-term gains by not maintaining assets and it often takes many years for the full effects of this neglect to become appare nt. To ensure that the value of the Authority' s assets are maintained , an Asset Management Branch has been es tablished to develop uniform preventative maintenance procedures and monitor the condition of the Authority' s assets throughout the State.

REFERENCE 'Conceptua l Optio ns for Regio nalisation of the Water Authorit y', Water Auth ority of Western Australia, August 1986 (unpu blished).

'WATER' TO BECOME Bl-MONTHLY In 1989 the publication of the Journal will increase to six issues per annum in accordance with the Council strategy of greater service to Members. • Authors will have increased opportunities for publication • Readers will gain a wider spread of features, news and special issues • Advertisers will have greater scope for contact with the industry For the six issues, the annual subscription will become $20 including surface mailing.


NSW SEMINAR Manage Assets Today - for Tomorrow Report by John Schlafrig The 19th and 20th April 1988 saw the first coordinated effort in evaluating the past, present and future of asset management in the New South Wales Water Industry in a seminar attended by some 180 from all sectors of the Industry, a well-structured program explored - Asset-related Problems and Issues - Asset Management and Corporate Performance - Allocation of Financial Reso urces and State/ National Develop ment - Technology for Effective Management of Assets - Future Directions for Managing Asset-related Problems - What to do? Form ulation of Strategies for Follow-up. Asset Management is making the best use of assets and involves the conception, planning and design, construction , maintenance and operation of any investment of val ue. In the Water Industry, these investments are of large magnitude and can be difficult and/ or costly to replace. In recent years, the industry has seen the large-scale construction programs of earlier times give way to a period of consolidation, accountability and efficiency optimisation. In New South Wales, there exists a large complex of service undertakings comprising almost 200 State, inter-State and Local Government authori ties with assets exceeding $30 billion in total replacement value. Initiated by the Department of Water Resources, NSW, this Seminar was arranged by a consortium of the DWR, A WW A, Public Works Department NSW, and the Local Government Engineers Association . The objective of the Seminar was to formulate an Industry Coordinated Strategy for Asset Management after identifying current problems during the course of the seminar. The opening address was presented by the Hon. Ian Causley, Minister for Natural Resources . The Government requires that the returns from the States infrastructure be maximised and the Treasury is preparing guidelines for evaluation of capital projects and asset appraisal within the context of a State Economic Development Strategy. The Minister stressed that the Industry, having experienced a period of infrastructure rapid expansion, needs to provide new and improved services whilst und er the severe constraints of high inflation , high un employment, high interest rates and unprecedented government deficits and debts. The earli er developed assets are showing signs of deterioration. 'As with people, it is not the natural ageing process that creates the problem, but rather it is the failure to prepare for the changes that ageing inevitably brings.' Concluding, the Minister suggested that the problem of asset management presented a challenge and an opportunity to achieve a solution which will be all-embracing , looking at such aspects as financial management and accounting procedures consistent with the best practices found in the private sector.

KEYNOTE ADDRESS Dr Penny Burns, fresh from her experiences with the Public Accounts Committee of South Australia, created the scene for the Seminar in revealing the South Australian approach to asset replacement. She advocates small-scale experimentation, utilising the experience of others and finally replacement modelling. Total asset replacement is unwarranted but an optimum percentage of replacement needs identification. Eighty percent of existing assets was adopted as the extent of asset replacement. The agency assets which were reviewed and programmed for maintenance/ replacement were in the Engineering & Water Supply Department, the South Australian Housing Trust, the Highways Department, the State Transport Authority, the Electricity Trust of South Australia, the Education Department and the Technical and Further Education Department. Heritage, land and natural resource assets were ignored by the SA PAC. In summary, Dr Burns'

John Schlafrig is Treasurer of the NSW Branch of A WWA. 20

WATER August, 1988

counsel for asset management is - feel the way and to some extent rely on hunches - start working on the solution to the problems; the information systems wi ll never be perfect until it is too late.

ASSET-RELATED PROBLEMS AND ISSUES IN LARG E AND SMALL PUBLIC AUTHORITIES IN NSW Mike Da) of the Hunter District Wate r Board described the effects up on asset management of the 'pay for use' charging policy. Deferral of some $40-50 m value of works for some 12-15 yea rs has been ach ieved. Conservation through greater community awareness a nd impact has also been ach ieved. Apart from these, an asset register capturing ome 700Jo of the Board' s assets is under preparation using Mincom so ftware; up-to-date technology is being applied together with attention to better use of existing resources by accounting for all water transfers, are methods employed by the Board as part of a detailed asset management strategy . Ron Gonsalves, the Tamworth City Engineer, explained that assets were upgraded and renovated in accordance wit h a shortterm program established by available budget and major corrective mainte nance requirements. Options available to the Council to commit funds to a longer-term program of rehabilitation and replacement will depend on the Minister 's suppo rt of trade waste charge structuring. Peter Ullma n, the Shire E ngineer of Manilla Shire Council outlined the Shire's assets and described the problems experienced. Asset Management was recognised as being practised on a day-to-day basis utilising whatever resources were available. He advocated the adoption of realistic asset identification, plant replacement programs and a preventative maintenance strategy. Alex Petlevanny from the Department of Water Resources, NSW, put the case for the large water authority. On present projections, in order to maintain the Department's service standards in the State's Irrigation Areas and Districts, the present level of expenditure on infrastructure refurbishment and replacement would need to be doubled. Limitations on resources will necessitate a closer asset management strategy embracing - an adequate and reliable asset database - appropriate performance indicators - financial management practices and procedures.

ASSET MANAGEMENT AND CORPORATE PERFORMANCE Barry Clark from PA Consulting Group introduced this area by looking at the characteristics of the capital intensive industries and their asset management implications. The interface between marketing, asset management and human resource strategies was examined in relation to the informatio n technology strategy. Wyong Shire Co uncil , represented by David Cathers, offered a description of the Shire's water and sewerage assets and value. Levels of service/performance were identified, performance indicators established and an asset register prepared. The asset register was tailored on an IBM XT personal computer using 'PCExpress'. Bob Hayward from Camp Scott Furphy Pty Ltd also related to performance indicators, information systems and levels of service in describing 'Infraworks'. The Wessex Water Authority (WW A) of the UK has estab lished an excellent reputation for computerised asset management systems. All aspects of asset management ')1/ere covered by David Beal and the computer-based system used by WW A, (Maintenance Management Information System MMIS) was described . A high degree of automated monitoring ensured that the available database was real time and supported the Management System procedures. The utilisation of telemetry was as advanced as Australia has seen.


ALLOCATION OF FINANCIAL RESOURCES AND STATE/NATIONAL DEVELOPMENT OPPORTUNITIES Eric Groom , formerly of the NSW Treasury, spo ke on the asset appraisal guidelines, and the general approach to capital works evaluation as app lied prior to the recent election. In frastructure needs were considered in aggregate with a view to filling gaps in existing infrast ru cture by reallocation or by extra funding if available. Eco nomic growt h and structural change (projected to be lo w), maintenance and rep lacement of existing assets we re also factors to be considered. Targets identified as desirable by investigative committees were; reversal o f decline of public involvement , rate of return target adopt ion and establishment of cost benefit guidelines. The Industrial Supplies Office was represented by Bob Keel ey. Its function is to provide Government Departments with information upon Australian-made products, particularly with reference to quality, delive ry time and reliabili ty. Dick Schneller described the National Engi neering Information Services based in Wollongong. It is a consulting service directed to promoting simple communication between contractor and client and protecting quality by the utilisation of uni versal specifications with tai lored additions.

TECHNOLOGY FOR EFFECTIVE MANAGEMENT OF ASSETS The Sydney Water Board has been confronted with the major rehabilitation of the oldest systems in Australia, involving restoration and replacement programs. Bob Cadden indicated that new techno logy has been utilised in the solution to the problem of identifying the need for work; remote inspection methods are just one of the latest techniques in sewer renovation. Ross Mackellar, City E ngi neer of Orange, advised that Asset Management has been carried on in one form or another for some time. Technology was defined and related to City's assets. Systems used for maintaining acceptable customer service levels, asset maintenance optimisation and general efficiency moni tor ing were identified including procedures, data collection and financial monitoring. John Anderson, Inspecting Engineer at the Public Works Department of New South Wales, talked about stretching the li fe of existing assets to allow time for the planning of future rehabilitation and replacement works. It was suggested there was some room for relaxi ng customer service levels to defer the construction of new facilities and updating the old, with significant cost benefits. One percent of present asse t worth per annum was deemed adequate to accumulate replacement cost by the time plant/ material life was at an end . New technology was agai n cited as a method of improving yield at existing treatment plants at economic levels. The risk and security aspects were a lso covered by Mr Anderson using terminal storages and extra capacity in these storages to provide a buffer in contingency situations. Alan Longstaff, a Director of Gutteridge Haskins and Davey based in the Melbourne office, likened asset management to a large painting comprising numerous elements. GH&D together with their US associates CH2M Hill have made availab le software for use on Personal Computers and developed primarily for water industry fundions. Alan stressed the need to utilise computerised systems for asset management to attain a more effective method of replacement and rehabilitation , identification and programming.

FUTURE DIRECTIONS FOR MANAGING ASSET RELATED PROBLEMS Peter Millington , Director of the NSW Department of Water Resources emphasized the need to take up the challenges and opportunities of the emerging problems of ageing and deteriorating infrastructure , to improve public sector efficiency and enhance the state's manufacturing and business sectors. Not only the Department but the entire water industry , in a unified approach to the problem , requires strategic asset management offering the benefits of; common problem resolution (saving waste in resources), the provision of better fram ework for identifying State needs and priorities and the provision of better

communication between utility bodies and the manu fact urers to ensure minimum lead times for su pply and t chnology development. Millington sugges ted that a working group be formed to address th e problems and issues of asset management, the group to comprise; representatives from State, Local Government and private sectors. This group, in 12-18 months, could identify the problems and issues faci ng the NSW Water Industry and highlight possible solutions. Councillor Black, Senior Vice President of the Shire Association of NSW, noted the aim of the Seminar to be the main tenance and preservation of assets rather than the 'throw away' alternative. Councils recognised the need to improved asse t utilisation and extend plant life but considered the method of financi ng requires review . Local Govern ment recognised the need for meticulo us management and would wish to be involved in the development of plans, the acquisition of in for .nation and the formulation of guidelines for councils, in consultation and cooperation with the DWR, Dept. of Local Government and the PWD on a continuing basis. Terry Charlton promoted improved comm unication between the asset owner and manufacturing with resulting manufacturer understanding of technology needs and consistent standards with consequent benefits in cost savings. There are many potential benefits in manu facturers participatin g in the asset management process but the water authority needs to start the ball rolling.

FORMULATION OF STRATEGIES FOR FOLLOWUP ACTION Discussion of the asset management problem together with questions from the floor in a forum style ensued with all speakers contributing. After discussion , the need for a working group was agreed and a 'Forum' constituted. This forum comprises the NSW Department of Water Resources (to convene and provide the secretariat to the Forum), Sydney Water Board, Hunter District Water Board , Public Works Department of NSW, Local Government and Shires Ass'n of NSW (Water Supply and Resources Committee), Australia n Water and Wastewater Association and Private Industry. The Forum is to evaluate options and recom mend to the Government, action , on the establishment of an asse t management program for the NSW Water Industry. 1 Evaluatio n and recommendations will require active, close interaction, and communication between the State and Local Governments and the public and private sectors of the NSW Water Industry. There was also agree ment that the Forum follow a 3-stage approach to asset manage ment: Stage I - identification of a ll key asset management problems and issues, and collating them into an overall picture of the NSW water industry . Stage II - promoting an awareness, throughout the Government and the community, of the importance of effective asset management and development of strategies to address key problems and issues. Stage III - the implementation of asset management strategies. Draft terms of reference for the Forum were as follows • To provide a forum for exchange of information, ideas, experiences, techniques and technology throughout the water industry on asset and infrastructure management issues. • To report back on the fo llowing to the individual member authorities a nd associations for any necessary action - A standardised approach to development of asset registers throughout the NSW water industry - The nature, magnitude and implications of the key asset management problems and issues confronting the water industry. - The promotion of an awareness of asset management problems and issues at both government and community levels - The development of appropriate performance indicators and standards of service with respect to assets and infrastructure - The promotion of greater interaction and co-operation between the public and private sectors with respect to asset and infrastructure management. T his rounded off the Seminar in a neat and constructive manner with the DWR and the NSW Water Industry setting off in a positive direction to establish their asset ma nage ment strategy. Output from this Forum will be of great interest to the NSW Water Industry and to the Australian Water Industry in ge neral. WATER August, 1988

21


WATER RECYCLING IN RESOURCES INDUSTRIES Allen J. Gale ABSTRACT The lack of readily obtainable water supplies throughout Western Australia and the growing emphasis on environmental protection is resulting in movement towards waste minimisation and product recovery in the resources industries. This paper describes the constraints on water recycling, the considerations required for water recycling and by way of example, some applications in Western Australia .

INTRODUCTION Water in Australia is a very limited resource and this is particularly so in the areas in Western Australia where many mineral resource undertakings are located (Figure 1). It is often difficult to locate a reliable source of satisfactory water even in close proximity to Perth . In general viewing of a map of Western Australia, there appears to be an abunda nce of streams. However, except in periods of exceptional rainfall, the majority of the streams are dry during the greater part of any year. Vast areas receive little or no rainfall and yields from catchments are very low due to the sandy soil conditions and salts absorbed by the precipitation as it passes through the soil into the groundwater often render groundwater supplies unsatisfactory for process use. The development of industry within existing population centres has led to increasing competition between domestic and industrial users for the available water. As a result, the need for water recycling has become increasingly evident. The incentive for water recycling has now increased to the point where high technology water recovery processes are being considered.

Allen J. Gale is an Associate Director of Binnie & Partners Pty Ltd and is State Manager for Western Australia. He is a Dip/ornate (Civil Engineering) of the Caulfield Institute of Technology (1968) and recently completed a Master of Engineering Science Degree at the University of Western Australia. He has specialised in the water management field for the last 18 years, working in most states of Australia, Asia and the USA. cost is 46 cents/ ml, without any major restrictions on supply at this stage. However, the readily developable water resources for the Perth area are recognised, they are finite and long-term planning has been undertaken by the Water Authority to evaluate options such as desalination or piping from the south-west or the Kimberleys, options which are very much more expensive than present supplies. Scheme water is piped long distances within Western Australia . Although the Perth-Kalgoorlie pipeline is the largest, there are other long pipelines serving other areas at costs which vary with quantity and location. To small consumers, a by-law price of 91 cents/ ml is generally applicable. For usage above 49 ml / day, a portion of the capital cost of the water supply scheme is apportioned to consumers. An extreme situation has developed in the eastern goldfields region, where the existing pipeline from Perth has reached its capacity. Users there are charged up to $5/ ml for excess water demand .

Groundwater - Frequently, the most reliable source of supply WATER CONSUMPTION IN RESOURCES DEVELOPMENTS Many mining, mineral and petrochemical developments consume vast quantities of water, far in excess of those required for domestic use by the population supporting the development. The situation is exacerbated by the need to utilize the lower grade ores for mineral extraction with the resulting increased tonnage of ore to be processed. Water quantity demands by some typical developmental projects are: 5,400 ml / d • Copper and zinc concentrates (1 ml / tonne product) 5,400 ml/ d • Nickel (1 ml /tonne product) 13,200 ml / d • Alumina (3.2 ml / tonne product) 2,400-4,500 ml/ d • Synthetic rutile (8-12 ml / tonne product) 6,300 ml/d • Ammonia urea 13,200 ml/d • Petrochemical 7,300 ml/d • Uranium (1,000 ml /to nne product) (Source - WA Department of Resources Development) The projects listed above consume as much water as a population in excess of 100,000.

is groundwater, with relatively small gold mining operations piping from a borefield up to 20 km away. However, the quality of groundwater is often not suita ble for direct use, due to salinity. For example, some of the groundv,ater in the goldfields region has a TDS of 150,000 mg/ L, or four times the salinity of seawater. Carbon-in-pulp gold processing can operate satisfactorily even with water of such high salinity and, as a result, restrictions on gold processing plants are not necessary . Careful process plant material selection is of course essential with salinities of this order. The extraction rates of groundwater must be monitored to ensure that depletion of the water resource does not occur. This is an important consideration in many areas close to Perth, where overextraction could result in seawater intrusion.

Surface Water -

The limited number of watercourses in Western Australia restricts the possibility of surface water inpoundments and high evaporation from relatively high surface area, shallow reservoirs, means recovery is low.

Reclaimed Water - Generally the population serving resources projects are small and the domestic demands are a minor component of the water consumption of the project. Accordingly, the quantity of domestic wastewater available for reclamation is small. Also, the degree of treatment normally applied is insufficient for use as process or cooling water. The main application of reclaimed wastewater is for watering recreational areas.

SOURCES OF WATER

ENVIRONMENTAL CONSIDERATIONS

The majority of mineral resource activities in the state are remote from the coastal areas (Figure 1) and where rainfall is extremely low . (For example, Kalgoorlie's average rainfall is 253 mm/annum and that for Geraldton is 470 mm/annum). The possible sources of water are: scheme water, groundwater, surface water, reclaimed wastewater.

The Environmental Protection Act gazetted in 1986 is of increasing significance to the mining industry. The new regulations require companies discharging wastes to carry a waste disposal licence. The licence stipulates certain conditions for discharge and stringent requirements mean that some additional form of treatment is required prior to disposal. The Act also gives the Environmental Protection Authority the power to enforce any conditions that it may impose, something not available under the prior legislation .

Scheme Water - The cost of scheme water varies with the area concerned and the volumes required. Within the Perth area the 22

WATER Augusl, 1988 ·


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This more recent technology has 1'een considered for disposal of more diffi cult wastes . However, the high operational costs usuall y make this option less attractive when compared with other alternatives. Very low suspended solids co~centrations are required to 'minimise the potential for clogging of the injection wet!.

Mine Backfill - Used in the mining industry for disposal of the large quantities of materials remaining after extraction or separation of the valuable components, this option is more relevant to the disposal of dewatered material than to liquid waste.

Tailings Dam -

The use of tailings dams is a common method of disposal fo r mining companies, and allows reuse of the clear decant follo wing settlement of the solids . A serious problem is the risk of releasing ·polluted water to groundwater or surface water supplies by seepage .

Irrigation - The use of partially treated effluent fo r irrigation of grass and crops is common practice for effluents from food processing, meat and domestic wastewater plants, but it is not common in the resources ind ustry. The presence of trace toxicants, such as heavy metals and mill reagents, along with high salinities, can present a problem .

Evaporation - The climate in Western

Australia makes the use of evaporation ponds an ideal method of disposal and containment. This method is particularly ea,, .. ,,,,h applicable away from populated centres, where land is relatively inexpensive. Contamination of groundwater by leachate can be a serious problem if appropriate safeguards are not taken. This may involve double-lined ponds with an intermediate leak detection zone . An examFigure 1 - Water resources projects in Western Australia. ple of such a system is shown in Figure 2. The costs of lining systems for permeable soils are high. For large DISPOSAL waste dischargers, the area required for evaporation ponds can be very large . For example, in the Perth area, 40 to 50 hectares of Options available for disposal of waste include: ocean, waterlagoons would be required for an effluent flow of 1,000 m'/d. course, groundwater, deep well injection, tailings dam, mine backfill, irrigation, evaporation. The degree of treatment required varies for each of these disposal options. Each option has POTENTIAL FOR REUSE constraints upon its applicability in the resources area. Brief comAll of the above disposal options have constraints upon their ments on the various approaches follows. applicability for a particular location and development. Taken in conjunction with greatly emphasized environmental reOcean - Disposal to the ocean by an outfall is an option quirements, reuse is becoming an increasingly viable consideraavailable to those industries in close proximity to the sea . The tion. quality criteria for discharge of effluent is defined in Bulletin 103 (1981) produced by the then Department of Conservation & Environment. Ocean disposal can require a relatively low degree of pretreatment compared to other disposal options, although nutrients and heavy metals limts are generally quite stringent. The high capital costs of the outfall, and the degree of pretreatment required often preclude ocean disposal. 0

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Watercourse - As with water supply, the relatively few permanent streams in Western Australia make disposal to watercourse an unlikely proposition .

Groundwater --There is increasing concern with the pollution of groundwater supplies in Western Australia . Because of the necessity to preserve this valuable resource, disposal to groundwater and the long term effects upon aquifer systems demands the most careful attention. Authorities are becoming increasingly aware of the significance of pollution or contamination of groundwater supplies and are correspondingly cautious as a result.

Figure 2 -

Typical double lined pond system. WATER August, 1988

23


The viability of treatment for reuse will relate to the cost and availability of other sources of water. When making comparisons, the costs of disposal of effluent must be included in the equation . In the resource industries, water is¡ used for a variety of purposes including: washi ng, cooling, slurry transfer, processing, steam generation. The water quality required for these different uses will vary widely, and the extent of treatment will be dependent on the point of reuse . Usually a number of water circuits can be estab lished within the plant permitting the use of a lower quality water in certain areas. This technique minimises the extent of treatment required for reuse , and in some instances permits the use of saline groundwater. Although this practice is common in the resources industry, in many cases more sophisticated forms of treatment do have to be considered. This is becoming an int reasing re-quirement, not only for existing industry but also fo r new developments. Additional to the need for reuse of water , the recovery of certain constituents from industrial effluents can be important. The process of recovery may be doubly advantageous in reducing the amount of waste, and increasing the efficiency and economy of the manufacturing process.

OPTIONS FOR TREATMENT PRIOR TO REUSE The extent of treatment required in a given situation will be dependent on environmental considerations and the required quality of water for reuse. Options for treatment applicable to the resources industry are: chemical, clarification, dewatering, filtration, desalination. Biological treatment is not normally necessary, as the organic content of process wastes generally is very low. Recycling will result in an accumulation of salts, the rate being dependent upon the water recovery rate. Salts may also be formed during the pretreatment processes, such as chemical treatment. Therefore, the aim normally is to prepare the effluent for salt removal.

achieve zero discharge status or where the only water supplies available are saline.

Residuals Disposal -

Regardless of the degree of water recovery attained, there is always a residue to be disposed of. The solids may be dewatered to minimise the volumes for disposal and to enable. them to be more easily handled. The reject from the desalination process will also require ultimate disposal. Therefore, a recovery of 90 to 950Jo of raw feed is the best that could be hoped for. Dewatered solids may be returned to the mine. The reject water normall y requ ires evaporation in a manner such as to prevent pollution of grou ndwater sources by the contaminants concentrated in the reject.

CONSIDERATION S FOR A REUSE PLANT Reliability - When considering reuse it is important to recognise that processing operations will be dependent upon reliable operation of the water recovery plant. Malfunction of the plant will directly affect the production process if no alternative source of suitable water is available. As the water recovery plant is essentially a closed system, apart from the residues evaporation pond , the evaporation system will be overloaded if the design degree of recovery is not achieved. For example, if a system is designed for 950Jo recovery, a reductio n to 900Jo recovery will result in twice the residue required for evaporation . As a consequence , the evaporation pond capacity will quickly be exceeded.

Flexibility - Being at the end of a processing plant , the raw feed

tion, but more often it is necessary for the removal of specific contaminants resulting from the concentration or refinement process. Lime treatment is by far the most common treatment in use today . However other treatment may be required for alkaline effluents, for organics removal , or where product recovery is being considered.

to the water recovery plant may vary widely, both in quantity and quality. Surge capacity must be provided at the head of the recovery plant to accommodate volumetric variations and to minimise the size of plant components. If water recovery is to be used at a new processing development, then the components of the wa ter recovery plant must have sufficient excess capacity to ha nd le a raw feed which varies from the design conditions. This requires oversizing of physical components and provision fo r upgrading of chemical feed rates. As each subsequent plant component is -reliant upon proper performance of upstream components, the plant should have emergenc y storage to accommodated ma lfunctions or breakdowns. This is in addition to the surge tanks at the head of the plant. 1

Clarification - This quite often represents the simplest form of

Standby Capacity -

Chemical Treatment - May be required simply for pH correc-

treatment for reuse applications. In other instances, it is used in conjunction with chemical treatment as a precursor to additional treatment. Clarification may range from a simple pond system which is desludged intermittently , to a continuous flow conventional steel or concrete tank fitted with a sludge removal mechanism.

Dewatering -

Sludge produced in the clarification process usually requires concentratio n prior to disposal, and provides an increased level of water recovery. A sludge lagoon may be used, but dewatering is very slow . If the drying sludge does not crack , then dewatering will be poor. For a greater degree of dewatering , equipment such as a filter press, belt press or vac uum filter can be considered.

Filtration - With the best of gravity settling installations used, fine materials will remain in the water , and additional straining or filtration will be required. Conventional rapid sand filters have long been used for this purpose , however multi-media filters have gained popularity in some areas. A more recent development is the microfiltration process where filtration down to submicron level is required . T he ability to remove smaller particles is most important with desalination processes such as reverse osmosis, where a high degree of removal of contaminants is essential to maximise the life of expensive membranes.

Desalination - Reverse osmosis or ion exchange represents the highest level of treatment in a water recovery process. It is an expensive option, both in capital and operating costs. As the membranes in a reverse osmosis system may be easily fouled, often irreversibly, then the highest and most secure degree of pretreatment should be provided. Desalination may be required to prevent a build-up of dissolved solids within a water circuit , to 24

WATER August, 1988

A water recovery plant often comprises high technology equipment and many drives. Failu re of one of these drives can put the whole plant out of service . To provide emergency maintenance in the event of breakdowns , standby pumps and similar items are a wise precaution , otherwise great reliance is placed on rapid attention from maintenance personnel. Interruption of operation is not only inconvenient it adds to plant instability while the plant 'settles down' after shu tdown and restart-up

Pilot Plant Testing -

The assessment of performance of a water recovery plant can be difficult, due to the complex nature of the feedwater. Pilot plant testing enables design requirements for plant components to be better defined as well as highlighting potential problem areas in the full-scale plant. Obviously, a feedwater with characteristics similar to the main plant must be available for the pilot plant , which may not be practicable for a new processing plant. The cost of pilot plant testing may initially seem high but the cost is justified by the more reliable design information obtained , the resulting economy in sizing the full-scale plant and identification of significant operating parameters and constraints.

EXAMPLES OF WATER RECOVERY SYSTEMS Synthetic Rutile Processing - A water recovery plant has been constructed for treatment of acidic effluent from a 112,500 tpa synthetic rutile plant near Geraldton, to produce a high quality water suitable for recycle within the process . High technology equipment, including a microfiltration unit and reverse osmosis system, are used to achieve a high degree of water recovery. This approach was dictated by environmental considerations and the limited supplies of scheme water available in the area. The shortage of water also resulted in optimisation of water usage within


11

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the processing plant to the extent that unit water consum ption is approximately half that fo r a similar plant elsewhere. The raw feedwater is of low pH and is high in sulphates, iron and manganese . The range of characteristics are: pH 1.5 to 2.5 Sulphates 10,000 to 15,000 mg/ L Iron 2,000 to 4,000 mg/ L Manganese 200 to 500 mg/ L The water recovery plant features the follo wing essential elements: - lined surge ponds for storage and balancing of effluent - line treatment to remove iron and manganese - soda ash treatment to remove calcium hardness - microfiltration to remove fin e solids and colloidal material - reverse osmosis to substantially remove dissolved solids - dewatering of sludge prior to disposal - evaporation ponds for storage of concentrated waste. A schematic of the process is presented in Figure 3. Balanced effluent fr om the surge ponds is dosed with lime slurry to adjust the pH to about 10. The resulting sludge is separated in a conventional clarifer and transferred to a belt press for dewatering . The clarified effluent overflows to an agitated tank where soda ash solution is dosed to remove calcium hardness remaining from the lime treatment stage. Flue gas is inj ected to reduce the soda ash requirement and to adj ust the pH to the minimum solubility point for calcium . Following secondary clarification , the pretreated effluent is fed to the microfiltration unit. The micro filter essentially comprises a number of long tubes through which the effluent passes (see photograph). The filtering action is achieved by means of a thin layer of solids that builds up on the filter to form a dynamic membrane. The thickness of this solids layer is controlled by maintaining a minimum velocity within the tubes. H ence, a proportion of the flow must always be rejected and is recycled back to the feed tank. A small bleed stream of solids concentrate is continuously discharged from the system. The permeate from the microfilter is chlorinated for disinfection and is discharged to the RO feedwater tank. The major difficulty with RO systems is the high standard of pretreatment required to prevent fouling of the RO membranes. Problem contaminants such as heavy metals, hardness, silica, organics and suspended solids must therefore be removed. The pretreatment system provides the required treatment. The micro filtration unit provides a high degree of security for the RO process. The RO system is the final stage in the treatment process. Antiscalant is dosed along with an appropriate amount of acid to reduce the pH below 6, to minimise the potential for calcium fouling. The water is then fed at high pressure through a series of membranes, producing a high quality permeate. The system is designed to provide a water recovery greater than 90%. The high water recovery is achieved in a two stage system where the reject from the first stage RO is passed through a seawater RO stage . The RO reject is used to liquify the sludge cake from the belt press, which is then pumped to double-lined evaporation ponds.

Although unusual to reliquify dewatered sludge, it is cheaper to pump the sludge to the evaporation ponds than to truck sludge cake back to the minesite. Also, dewatering maximises water recovery and minimises the size of the evaporation ponds.

Micro filter

Kwinana Nickel Refinery - Wastewater from the refinery discharges to tailings dams. Leakage from the tailings dams results in contamination of gro und water . Control of contamination has requ ired recovery bores from which the water is returned to the plant. Through an intensive program of water conservation , the refinery has, since 1980, reduced its total water consumption by over 40%. Over the same period , scheme water usage has been cut by a further 45% through reclamation of water from the tailings dam. The water recovery scheme incorporates a reverse osmosis system which, as well as providing high quality water for reuse, produces a concentrate from which product can be recovered. The recovery scheme is proving effective and the gro undwater qualit y is improving . Kwinana Alumina Refinery - Leakage of effluent from residue storage ponds on the refinery site has led to contamination of gro undwater in the area. As part of the containment policy, a number of recovery bores have been established. This water is no w reused in cooling circuits and has substantially reduced scheme water requirements for this purpose , as well as containing gro undwater contamination . CONTINUED ON PAGE 44

WATER August, 1988

25


ASSET REPLACEMENT IN THE FUTURE W. David Woodhead and S. N. Tucker SUMMARY This paper describes the international recognition given to infrastructure deterioration. Replacement of infrastructure assets is becoming an important issue.,in Australia and a significant report has been presented to the Federal Parliament summarising the situation and making recommendations. Deterioration creates. opportunities for changing the infrastructure when it is rebuilt, to better reflect the needs of current and future populations, and social and technological trends. Asset replacement becomes an issue at a time when the provision of long-term capital for public works at relatively low rates of interest is increasingly difficult. A study in South Australia has estimated the future demand for capital fo r different types of infrastructure asset and reveals the need for a very substantial increase until the turn of the century. Both technical and financial aspects are subj ect to research, and include the investigation of material degradation and replacement techniques as well as requirements and strategies for the provision of finance .

BACKGROUND International Perspective In recent years the replacement and development of infrastructure has become a topic of vital importance in most western economies. The US Congress in October 1984 set up the National Council on Public Works Improvement. Categories of infrastructure which received separate consideration included: • airports and airways, • highways, streets, roads and bridges, • mass transit, • intermodal transportation , • wastewater management , • water resources, • water supply, • hazardous waste management, and • solid waste. The first report from the Council , entitled 'The Nation's Public Works: Defining the Issues' (1986), concluded that there was a need to : • examine changing relationships in the Federal system, • explore different sources of fundin g, • re-evaluate the criteria and procedures used to establish public works needs, • examine potential improvements in decision support systems, and • make better use of technological advances . In the UK, infrastructure issues are discussed on an official basis within the National Economic Development Organisation, with representation from government, management, and unions. This organisation concluded (Cassels, 1986) there was a need to: • improve basic information and decision making processes, • improve community debate on infrastructure, particularly relating to acceptable standards, • eliminate the grievous defects in the current state of much of the infrastructure, and • recognise the employment implications of major public spending decisions.

Australian Perspective Concern about declining Australian investment in infrastructure led, in 1985, to the formation of the National Infrastructure Committee (NIC) , with a broadly-based membership drawn from business, unions , community groups, and government. This

David Woodhead graduated with Honours in Forestry at A berdeen, Sco tland, and with a Masters Degree from the Un iversity of California. He is a Principal Experimental Scientist with the Division of Construction and Engineering of CSIRO . H e leads a research program into productivity, management techniques, resource use and has made particular study of innovation and the operation of the workforce in housebu ilding. M r Wood head is currently developing management tools fo r use by small housebuilders companies to improve their cost estimation and scheduling. Dr Selwyn Tucker, B.Sc.(Qld), Ph.D.(ANU), graduated as a physicist, he is currently a Principal Research Scientist in the Life Cycle Performance gro up at the CSIRO Division of Co nstruction and Engineering in Melbourne. His in volvement with computer modelling proved a necessary requirement for projects being undertaken by the Building Operations and Economics section of the CS!RO Division of Building Research which he j oined in 1971. His research activities have produced practical applicatio ns in building economics where there has been an emphasis on computer-based techniques.

W . D. Woodhead

Dr S. N . Tucker

resulted in a National Infrastructure norum being held in October of that year. The House of Representatives Standing Committee on Expenditure recognised the importance of the trends in infrastructure investment and established an Infrastructure Inquiry in l.986 . This Inquiry was chaired by Mr John Langmore, MP and became known as the 'Langmore Inquiry' . A report was issued (House of Representatives Standing Committee on Transport, Communications and Infrastructure , 1987) .

THE LANGMORE REPORT The Findings Essentially these identify a substantially increased need for public expenditure due to the aging of Australia's infrastructure facilities, which follows a similar pattern to that found overseas. The need for expenditure is likely to rise rapidly as some faci lities, notably water supply and sewerage installations, reach a stage of deterioration where renewal becomes critical. This renewal will be proceeding at the same time as gaps in the initial provision of infrastructure are still being filled . Demograp hic changes may alleviate pressure on some facilities but aging of the population may increase others. Technological advances have the potential to achieve efficiencies in some areas but there is the risk of under-investment in Australian public sector technology. The funding of infrastructure provision and renewal is an area where far-reaching choices, will have to be made as to the sources and extent of funds. Research is required on both technological and fi nancial aspects, to devise appropriate practices and to obtain the funds to implement them .

Recommendations of the Report This paper was presented at the A WWA Summer School 1988 in Tasmania. Th e School th eme was 'Optimising The Use of Assets'. 28

WATER August, /988

I . The declining tren d of public investment be reversed and preparation be made for increased pub lic investment for th e remainder of this century. (Pa ra 2.32) (R efer to Figure l).


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hospitals, highways, transport, water supply and sewage disposal, schools and colleges, together with a summary. The major conclusion of the water and sewerage report (1987a) is summarised in Figure 2. The cost of replacing assets will rise quickly to a peak of $667 m in the five years to 2005 and then decline to half this sum, over the following 20 years. The peak in the five years to 2005 is eight times that required in the five years to 1990 and 10 times that currently spent in a five-year period . The main components of replacement cost are water and sewerage services , with irrigation , plant and buildings being less than 10% . The costs are in real terms, i.e. current dollars. This model, developed by the South Australian Engineering and Water Supply Department, illustrates the current state of modelling to predict fut ure fundi ng requirements. The model takes into accou nt current replacemen t practice , estimated economic lives, age distribution of assets and weighted average costs of rep laceme nt. The variations in lifetimes due to faulty construction techniques and know n high corrosivity areas are allowed for by adopti ng di fferent life assu mptio ns for affected sub-groups of assets.

Figure 1. AUSTRALIAN PUBLIC AND PRIVATE CAPITAL FORMATION 1901-1986 (AS A PERCENTAGE OF GDP). Source: A. Barnard and N. G. Bullin, 'A ustralian Public and Private Capital Formation 1901 -75', Economic Record, December 198 1; ABS 5204.0. 600

2. The Government should give high priority to promoting research and development by CSIRO, universities and other pub lic auth orities related to improving the efficiency and effectiveness of the provisio n a nd the management of infrastructure. In particu lar, the CSIRO proposal for a four year infrastructure research program should be supported. (Para 4.13) 3. The Government shou ld apply a st ricter separation between its capital and current accounts so that the commonwealth budget deficit is recorded in line with conventiona l accounting practi ce . (Para 6.39) 4. The Government should exclude the borrowings of com mercial public authorities from the Public Sector Borrowing Req uirement. (Para 6.46) 5. Consideration should be given to positive incentives to volu ntary saving as exist in Japan and as are proposed in Sweden. (Pa ra 6.60) 6. The Government should review the controls over government business enterprises outlined in its policy inform ation paper with a view to allowing a higher leve l of managerial autonomy. Accountabi li ty should be assured through better specification of desired results and agreed, periodic review of performance after the event. (Para 7.30) 7. The Government should cons ider comp lementin g the asset management work undertaken by the former Department of Hou sing and Construction with resea rch by its successor and by CS IRO into analysis of the asset replacement problem , st rategies for asset management and resea rch into construction material s and practi ces. (Para 7.32) 8. The Department of finance should complete and issue its proposed manual on benefit-cost analys is as soon as poss ible. (Para 7.4 1) 9. The Government should act to remove the di storting effects on all ocative and operational effi ciency of unintended cross-subsidies. IO . The Loan Council should attempt at least some broad measure of priority-setting and coordination of major public invest ment proposals. (Para 8.33)

CURRENT ACTIVITY Infrastructure Conference The Second National Infrastructure Conference entitled 'Dollars and Directions' was held in Canberra in April 1988. The forum provided an opportunity for discussion on a wide range of opinions and policies, following publication of the Report of the House of Representatives Standing Committee on Expenditure. It is anticipated that the function will lead to the formulation of policies on funding and technology and will determine the way Australia handles the phenomenon of aging infrastructure.

The South Australian Experience In this context, one of the more significant contributions to infrastructure research in Australia has been made through the work of the South Australian Parliamentary Public Accounts Committee (1987a,b) . This body identified the major categories of assets managed by the South Australian Government and the assets themselves. Using the year 1985 as a datum, the future costs of replacing the assets were calculated. The findings of the two-year study were presented in eight parliamentary reports dealing with housing, electricity supply,

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2030 -

2035 BUILD

Figure 2. SOUTH AUSTRALIAN ENGINEERING AND WATER SUPPLY DEPARTMENT - SUMMARY OF REPLACEMENT PROJECTIONS 1986-2035. Source: South Australian Parliamentary Public Accounts Committee Report of the Public Accounts Committee .

51 st

The expected replacements are based on a number of assumptions : all replacements to be on a one-for-one basis, and current technology assumed. In essence, the costs are based on maintaining the status quo of the current facilities. In South Australia there was insufficient data to allow investigation as to whether the income from users of the facilities was sufficient to pay for the operating and investment costs. The results of the study indicated areas where capital financial problems will occur in the future but offered no options for the effects of new technology changing demands, or rationalisation of assets.

Opportunities Created by Replacement The replacement of worn out infrastructure creates the opportunity to plan capacity and levels of service to match the characteristics and needs of the present and future populations. Redundant infrastructure can be shut down and existing parts of systems replaced in kind or modified, to reflect shifting population patterns and social and technological trends. The nature of the adopted replacement will itself have an effect on resulting trends and asset replacement is therefore a powerful planning instrument. While there is a general belief that the policy response in replacement should be to increase urban density, there are many qualifications resulting from local conditions and the type of infrastructure to be replaced. For example, the South Australian report on water supply and sewage disposal (South Australian Parliamentary Public Works Committee, 1987a), indicates that increasing density in established areas with a small scale of working, will result in higher costs than in the more spacious city WATER August, /988

29


fringe. Conversely, a report prepared for the City of Melbourne estimates substantial benefits resulting from re-establishment in urban areas (Neilson Associates, 1987). Factors which influence planning include change in recreational planning to respond more effectively to Australians' use of leisure time, new concepts of urban design , altered thinking about road layouts and residential street management and local economic development. Social changes include more small and single parent households, increased poverty, appreciation of the needs of women, the disabled , the old and the young, increasing difficulty in obtaining access to affordable shelter and employment, attempts at local job creation and community development, and more flexible working arrangements.

THE FUTURE The need to increase the level of research devoted to infrastructure issues was highlighted in a press release of the NIC entitled, 'Mini Budget Highlights Need for Infrastructure Research ' (NIC, 1986), which pointed out the need for research to: • assess needs and establish priorities, • develop techniques to rate infrastructure projects depending on selected criteria, • develop and apply new technology to management, provision, and maintenance, and • examine the implementation of novel methods of funding .

Financial It is envisaged that financial research would link quantitative estimates of service life of assets, resulting from technical research , with financial criteria, to derive optimum strategies. In the area of commercial buildings, which also involves long life spans, an understanding is being gained of the impact of individual parameters on the project cost (Tucker, I 987) and this is of direct relevance to infrastructure issues. For each infrastructure category, CSIRO has suggested the concept of a 'justification index', based on an assessment of the potential for reduced unit costs through the application of improved construction technologies. For a particular category of infrastructure the parameter would be a function of the total cost and the potential reduction in unit cost. The value of the 'justification index' could be used to measure the need for research on improved construction technologies applicable to a particular category. Decisions as to alternative solutions to asset replacement and how they are to be paid for, have been hampered by lack of knowledge of initial costs and recurring maintenance and running costs of the facilities. Improved monitoring and record keeping is now starting to reveal the actual costs of owning and operating facilities, but a greater understanding of the complex interactions is needed.

Technology Rapidly changing technology is a fact of 20th century life and this applies with equal force to the ma~erials and practices used in construction. Technological advances shpuld encompass: • more efficient application of existing,eonstruction technologies, • the application to construction of existing technologies currently being applied in other sectors, and • the development of alternative construction technologies. An important parameter in evaluating financial aspects is the anticipated service life, and research to determine values for various types of asset is an important task to be undertaken . This technical parameter would be based on criteria such as: • understanding product function in relation to environmental factors and material properties, • modelling degradation mechanisms to maintenance or failure points in terms of environmental factors, • developing operational hazards or geographical hazard maps for planning guidance, and • developing predictive simulative tests to aid new material development and product design improvements . 30

WATER August, 1988

Research A number of proposals are being considered currently, to carry out research relating to national public infrastructure in Australia. If implemented they will collectively contribute substantially to improved knowledge of assets and how to manage them. The studies of the South Australian Public Accounts Committee on infrastructure replacement indicate that a high priority should be given to water supply, drainage and sewerage facilities, both with regard to replacement and maintenance . It would appear logical that the results are likely to apply to Australia as a whole . Accordingly at the initial stages of research, increased effort is likely to be directed to the topic of pipes. South Australia is followin g up its earlier reports and developing policies for future management and replacement of its assets. The University of Melbourne is also proposing to set up a group to study infrastructure management ancf replacement policy making. The CSIRO Division of Construction and Engineering has developed a research project proposal which will be launched at the 1988 NIC Conference. Its objecti es are to analyse public infrastructure problems and to develop systems for forecasting, management and maintenance of the facilities . It is planned as a substantial project with half the cost being contributed by major public and private corporations. The Organisation has considerable expertise in financial evaluation and life-cycle costs in relation to buildings, which is directly applicable to infrastructure topics. Research has already been directed to individual projects which are part of the infrastructure, and findings from these studies will have a general applicability . For example, the CSIRO Division of Construction and Engineering has just completed research for the Melbourne and Metropolitan Board of Wor ks, on pressure fluctuations in water supply lines. This included a determination of the critical environmental factors that govern fatigue life. Pipe properties were measured, a simulative test procedure designed and a Predicted Service Life (PSL) model developed. In another area, adhesion expertise in CSIRO has developed new theories for optimum bonding which will contribute to improved performance of sealings and connections. A prototype 'expert system' has been developed in a collaborative project between the CSIRO Division of Construction and Engineering and the Melbourn~ and Metropolitan Board of Works (Thompson et al, 1987). (Vide report 'Smart Capital' in this issue (Ed .)).

CONCLUSIONS Discussion is starting on the issue of infrastructure asset replacement. The aging of structures and premature maintenance and replacement due to poor performance will require increased spending during the next few decades. Public sector finance as a percentage of GDP is declining and the provision of finance is accordingly a critical issue . Hard decisions as to priorities and sound planning of their implementation will be required. Research is needed to provide solutions to existing problems, to create improved and more efficient procedures and processes and to develop novel methods of financing . Questions arise as to the expectations and standards of the services which should be provided; these issues will be the subject of community debate .

REFERENCES BLAKEY , F. A. and GERRARD, C. M. (1987). Delerioration of the national infrastructure - will we act in time? Proc. Facilities Management '87 Conf. , National Committee on Rationalised Building (NCRB), Melbourne, pp . 35-45 . CASSELS , J. S. (1986). The Infrastructure: Fi nding a Bet ter Way. National Economic Development Office , O'Sullivan Lecture, Imperial College, University of London. FLOOD , J. , WOODHEAD, W.-D. and TUCKER, S. N. (1985). Evaluation of the impact of housing expenditure. Australian Housing Research Council Report on Project 145 (AHRC: Canberra). HOUSE OF REPRE SEN TATIVES STANDING COMMITTEE ON TRANSPORT, COMMUNICATIONS AND INFRASTRUCTU RE (1987). Constructing and Restructuring Australia's Public Infrast ructure. Australian Government Publi shing Service, Canberra.

CONTINUED ON PAGE 44


OIL FROM SLUDGE: A COST EFFE.CTIVE SLUDGE MANAGEMENT SYSTEM T. R. Bridle and C. K. Hertle ABSTRACT Sludge management techniques in the sewage treatment industry are responding to both increasing processing costs and stricter environmental regulations. Both these factors have spurred development of energy efficient non agricultural-based sludge management systems, with the most promising of these being the Oil from Sludge technology. This relatively low temperature, atmospheric pressure process converts the volatile organics to straight chain hydrocarbons , much like the principal ingredients of diesel fuel. The technology, which has been tested at pilot plant scale in Canada, is currently undergoing an extensive developmental program in Western Australia. The existing data reveals that oil yields of 30% from raw mixed sewage sludges and 15% from digested sludges are routinely achieved. Initial analysis of Australian sludges indicates that oil yields will be much higher. Preliminary economic assessment of the technology suggests that while plant capital costs are simlar to sludge incineration, operating costs are predicted to be $100 to $150 per tonne lower.

INTRODUCTION Sewage sludge is an unavoidable byproduct of wastewater treatment and roughly one tonne of raw sludge is produced per 5000 m3 of wastewater treated. It is estimated that over 220,000 dry tonnes of sludge are produced annually in Australia and disposed of at a cost exceeding $35 million. The major sludge disposal options currentl y used in Australia include agricultural utilization, ocean disposal and incineration . The total costs for those disposal options vary from about $JOO/ tonne for agricultural based systems up to $1000/tonne for incineration system (Proctor and Redfern, 1986). While the costs for incineration are very high, the trend in both Europe and North America is toward these thermal based technologies. It appears the reason for this trend is the increasingly stringent environmental regulations being enforced for land-based technologies . Of most concern is the fate of heavy metals and pathogens in these disposal options. This trend has spurred development of more energy efficient thermal based technologies in attempts to reduce operating costs. Numerous sludge processing options have the potential to convert a fraction of the organic material in sewage sludge into usable energy, but only a few have been demonstrated to be viable net energy producers at full scale. Processes such as starved air incineration, gasification and 32

WATER Augusr, 1988

liquefaction are in developmental stages and a thorough review of these technologies is presented elsewhere (Bridle and Campbell 1983). However, the most promising technology appears to be low temperature conversion of sludge to liquid fuels (Bridle, 1982). The basic concept of low temperature conversion of sewage sludge to produce fuel products has been known for many years (Shibata, 1939), but it is only recently that German researchers made significant advances in understanding the mechanisms by which sludge is converted to oil (Bayer and Kutubuddin , 1982). They heated dried sludge to 350°C in an oxygen free environment for about 30 minutes, producing an oil, char, gas and water. Oil yields ranged from 18 to 27% and char yields from 50 to 60%. The oil had a heating value of about 39 MJ/kg and the char about 15 MJ / kg. The researchers postulated that catalysed vapour phase reactions converted the lipids and proteins in sludge to straight chain hydrocarbons, much like those in natural crude oil. Analysis of the product oil confirmed that alkanes were produced, in contrast to all other pyrolysis processes, which produce cyclic and aromatic compounds irrespective of the substate used (eg. sludge, refuse or cellulose). The scientists identified that the aluminosilicates and heavy metals present in sludge catalyse the reactions. In 1982 Environment Canada embarked on a major technology development program to assess the viability of the oil from sludge (OFS) process and to develop a continuous reactor system to effect the conversion. This program consisted of preliminary batch tests to validate the German results, development and testing of a continuous bench-scale reactor and finally testing of the process using a one tonne per day pilot plant. As a result of this work a patented reactor system was developed (Bridle and Campbell, 1986). Campbell Environmental Ltd (CEL) has entered into an exclusive licence agreement with Canadian Patents and Development Ltd for the Australasian and S.E. Asian rights to the technology . In October 1987, CEL commenced construction of a second-generation one tonne per day pilot plant in Perth, Western Australia. This pilot plant was completed in April 1988 and is currently generating an extensive database for Australian sludges.

EQUIPMENT AND PROCESS DESCRIPTION A schematic of the reactor, used in the bench-scale system and both the Canadian and Australian pilot plants is depicted in Figure 1. In the bench-scale system the

Trevor Bridle

Chris Hertle

Trevor Bridle, B.Sc.(Chem.Eng.), M.I.E.Aust., is the Managing Director of Campbell Environmental Ltd in Perth, Western Australia. He has over 20 years experience in the environmental control field in Canada and Australia. Prior to joining Campbell Environmental he was with Environment Canada's Wastewater Technology Centre in Burlington, Canada. Chris Hertle, B.E. (Hons.) Chemical, M .J.E.Aust. is an Environmental Control Engineer with Camp bell Environmental Limited. He has extensive experience in sludge handling and management techniques with particular reference to sludge dewatering and ultimate disposal.

reactor is 5 cm diameter and 100 cm long; the pilot plant reactor is 25 cm diameter and 3.2m long. Nominal sludge throughput in the bench-scale system is I kg/ hr and in the ¡pilot plant, 40 kg/ hr. The reactor is subdivided by a helical gas seal into a volatilisation zone and a char/gas contact zone. Solids retention time (SRT) in the reactor is controlled by varying both the sludge feed rate and the reactor inventory. Sludge is fed to the reactor by a calibrated screw feeder and travels through the reactor by means of the reactor conveyor. Volatilised material is withdrawn from the first zone and contacted with the char in either a counter-current or co-current mode in the second zone. Gas contact time in the second zone is variable, up to 30 seconds. Figure 2 depicts the pilot plant as constructed by CEL. The CEL and Canadian pilot plants differ in the form of heating and oil/ water separation . The Canadian unit has a single propane combustor providing hot flue gas to the reactor and also uses a gravity oil/water separator. The CEL system is skid mounted and designed to fit into a container for easy transport. The pilot plant comprises a 1 m3 sludge hopper, a SCR controlled sludge feed system, a 25 cm diameter by 3.2 m long reactor, a char discharge system, a packed tower direct contact condenser, a disc centrifuge for oil/water separation and a heat exchanger for cooling of recycle water to


Sludge Bin

__

,..._

__,

+NCG GAS FLOW

Oil

--~

~

Furna~~ 7

,~ ---

k VOLATILISATION -;;,k--

----

CATALYSED REACTION ZONE

ZONE

__J

Char Bin

Figure 1. Schematic of Bench-Scale Reactor: '

the condenser. The reactor is heated by four propane-fired burners, mounted on the ann ulus surrounding the reactor. Burners 1 and 2 are rated at 45 kw and burners 3 and 4 at 15 kw. Burner I is designed to burn the non-condensable gas (NCG) produced by the process. The reactor shell is manufactured from 253MA stainless steel and al l other high temperature process equipment manufacturerd from 316 stainless. This system is currently located at the Water Authority of Western Australia (WA WA) Subiaco Sewage Treatment Plant in Perth, Western Australia . Test runs are conducted in th e following manner. First the entire reactor is brought up to operating temperature, normally 450°C. The water recirculation to the condenser is started , as is the disc centrifuge. Dried sludge (95% solids) is then fed to the system at the desired feed rate and the reactor screw is set to provide the design SRT and char inventory in the system. Wi thin 5 to 10 minutes of feeding sludge, gases are evolved, condensed and separated in the cen trifu ge. Char discharge is controlled by high and low level microwave switches in the char discharge shute. The system is operated at two to three SRTs before steady state conditions are reached and data collection is commenced. Operating pressure is controlled by a control valve in the NCG line and the maximum design pressure is 35 kPa.

EXISTING DAT A BASE Bench Scale System The I kg/ hr bench-scale system has been operated using eighteen differen t sludges from Canada, the USA and the United Kingdom. A summary of representative process performance is shown in Table I . Additional results from the TABLE 1. REPRESENTATIVE OPERATING CONDITIONS AND RESULTS Raw Digested Sludge Sludge Volatile Vo latile So lids Solids 60-80% 50-70%

Feedraie (g/ h) Temperat ure ( 0 C) Solids Retention Time (min) OIL Yield( %) Viscosity (cstk s) Calorific Value (MJ/ kg)

750 450 20

750 450 20

24- 46 23-62 33 - 38

13-29 9- 87 32- 42

40- 66 7-23

41-73 6- 17

3- 10 2- 6

4- 12 4- 6

3- 10

7- 16

CHAR

Yield( % ) Calorific Value (MJ/ kg) NCG

Yield(%) Calorific Value (MJ / kg) REACTION WATER

Yield(%)

NCG to &.ner ,,

Sludge Feed $o,ew

°' T,.-.

S10,age

cw ...,, Aec.-culat.on

e....,..,

Figure 2. Schematic of CEL OFS Pilot-Plant.

bench-scale system Jlave been presented previously (Bridle and Campbell, 1983 , 1984, 1986a; Campbell and Bridle, 1985). The information in Table I has been separated into mixed raw and anaerobically digested wastewater sludges. It is obvious that the oil yield from raw sludge is generally greater than that from digested sludge. This is as expected because the volatile material which is destroyed through the digestion process represents precursors which would have been converted to oil in the process . Oil yields expressed as a percentage of total solids , range from a low of 13% for an anaero bically digestrd sludge to a high of 460Jo for a mixed raw sludge and are primarily a func tion of the operating temperature and the sludge sou rce. Char yields vary from 40% to 73% at the optimum operating te mperature. CG yields vary from 3 OJo to 12 OJo and are primari ly a function of operating tempe rature. Production of reaction water varies from 3% to 16% and does not appear to be directly related to any of the operating variables. Thermal efficiencies of greater than 95% are routinely obtained with the bench-scale reactor. The elemental characteristics of the oil are quite stable over a wide range of operating conditions. Typical values for C, H, 0, N and Sare 76%, 11%, 6.5%, 4% and 0.5% respectively. Generally the oil contains less than 7% oxygen, but levels as low as 2% are achieved when the reactor is operated in counter-current mode. Detailed chemical analysis of these oils reveal they are comprised essentially of saturated alkanes, with Cl6 to Cl8 predominating. The effect of temperature on the oil yield is illustrated in Figure 3. T he data for oil yield in Figure 3 have been plotted on the basis of volatile solids rather than total solids. This use of volatile solids as the basis on which oil yield is calcu lated, in effect normalizes the results to account for the fact that raw sludge generally has higher volatile solids than digested . Even with this normalization, the yield from raw sludge is still generally higher than that from the digested sludge. This indicates that the volatile solids in the raw sludge contain more of the components which are ultimately converted to oil than do those in digested sludge. The volatile solids which are destroyed during digestion constitute a very high percentage of the oil precursors. Although the oil yield varies significantly from sludge to sludge, the effect of temperature is identical for all sludges. The oil yield increases with increasing temperature until it reaches a maximum in the 400 to 450°C range . Above the optimum temperature the yield begins to decrease as conditions favour the formation of increasing quantities of NCG . Sufficient data is not available to pin -point the exact shape of the temperature/ yield curve but it is obvious that the optimum, for all practical purposes, is a range as opposed to one specific point. In engineering terms, this is extremely important because it indicates a very stable operating system (ie. if the temperature fluctuates to some degree due to other perturbations within the system, the process will not fail). No clear relaWATER A ugust, 1988

33


60 ---- Digested - - Raw

50

'iii > 40 15 - -o

~ -0

al

>- ' 30

0

I I I I

/

/

20

I /

I I

/

10

/

/

/

/

/

I

325

275

375

525

475

425

575

Temperature [ • CJ

Figure 3. Effect of Temperature on Oil Yield (Bench-Scale).

tionship between temperature and oil calorific value has yet been identified but the viscosity of the oil has been found to decrease with increasing temperature, indicating that some thermal cracking of the oil is occurring. Char yields are generally higher for digested sludges, and char yield decreases with increasing processing temperature (Campbell, Bridle and Legault, 1987).

Pilot Plant The CEL pilot plant has only been operational since April 1988 and definitive data is as yet unavailable. The Canadian pilot plant has been operational since early 1987, and operational data from Canadian and USA sludges are available. Comparative bench and pilot scale results for two different digested sludges with the Canadian reactor operating in cocurrent mode, are shown in Table 2. In

terms of gross parameters the comparision between the bench and pilot systems is quite acceptable. T he oil yields and the calorific value of the oils are essentially the same. The oil from the pilot plant, for the Canadian sludge, appears to have a slightly lower viscosity than that from the bench-scale system. Elemental analysis of the pilot plant oils is in progress. The char yields from bench and pilot-scale runs are generally comparable but calorific values are not available. The production of reaction water is similar for both plants. This data indicates that the 40 fo ld scale up to pilot plant scale has had no significant effect on process performance. This indicates that there are no perceivable engineering reasons why scale up from pilot to full-scale cannot proceed.

Environmental Considerations The contaminants in sludge of most concern from both an environmental and

TABLE 2. COMPARISON OF BENCH-SCALE AND PILOT-SCALE RESULTS USA Digested Sludge

Canadian Digested Sludge

Bench

Pilot

Bench

Pilot

Feedrate (kg/ h) Temperatu re ( 0 C) Solids Retentio n T ime (M in)

0. 75 450 15

17 450 20

0.75 425 17

24 425 20

OIL Yield(%) Viscosit y (cstks) Calorific Value (MJ / kg)

15.6 14.4 42.5

10- 14 14- 20 43-45

12.3 32.4 41

9- 13 21 - 26 41

CHAR Yield(%) Calorific Value (MJ / kg)

62.8 8.6

52-7 1 na

73 .4 5.9

61 - 69 na

NCG Yield (%) Calorific Value (MJ / kg)

8.1 4

na na

3.3 7. 0

na na

REACTION WATER Yield(%)

34

WATER August, 1988

10.6

10- 17

6.6

5 12

human health protection point of view are pathogens, viruses and heavy metals. The OFS process, operating at 450°C with gas retention times of around 30 seconds ensures 100% inactivation of all pathogens and viruses. In addition, at 450°C, essentially all the heavy metals in the sludge remain in the char. (Bridle and Campbell , 1983). Since in an integrated OFS plant the char and NCG will be combusted to provide the energy needed for both drying the sludge and heating the reactor, the metals will be converted to oxides and silicates in the high temperature oxidative combustor. Extensive leach testing of these ashes has indicated that the metals are non-mobile and ill not leach to the groundwater (Brid le et al, 1987). Odours from an OFS plant will be contained since the reactor system is completely sealed. In add ition, the air needed for combustion of the char and gas will be process ai r from the sludge dewatering and drying operations, further minimising odours . Finally, the produced water will be used to quench the char prior to combustion. Hence the OFS process can be considered to be an environmentally benign technology, with minimal negative impact.

CEL's DEVELOPMENT PROGRAM CEL's pilot plant operation commenced at WA WA's Subiaco STP in April and will continue until the end of 1988. The research and developmental program will meet the followin g objectives: (i) Validation of the modified process operating on Australian sludges (ii) Generation of process design and economic dah for full-scale plants and (iii) Diesel engine testing of the oil produced. To meet these objectives CEL has developed a detailed experimental program which will assess sludges from three of WA WA's treatment plants, namely Sub iaco, Beenyup and Woodmans Point. Both Sub iaco and Beenyup are secondary treatment plants, with Subiaco producing digested and Beenyup producing raw sludge. Woodmans Point is a primary treatment plant, incorporating sludge digestion . CEL has been fortunate to be able to contract wit h WA WA, Westrail and the State Energy Commission of WA to conduct all the necessary analyses on the sludges and products, as well as the diesel engine testing of the oil. SECW A will conduct the diesel engine testing program, initially using a research VARIMAX engine, followed by testing in a 25-70 kV A multicylinder engine and finally, testing on stationary diesels located in a country power station. This testing will confirm the oil 's end use as a diesel fuel. This developmental program will be completed by the end of 1988, with the diesel engine testing continuing in early 1989 .

PROCESS ECONOMICS In order to develop projected costs for an OFS plant, a standardised integrated


plant flowsheet was developed (Figure 4). This conceptual plant comprises sludge dewatering, drying and conversion to oil, combustion of by-products with energy recovery and appropriate air pollution control equipment. Sludge dewatering is based on pressure filters, with demonstrated capability of producing a sludge cake of between 35 and 400Jo total solids. Drying is based on indirect steam drying with mechanical vapour recompression for energy recovery. Such driers routinely produce sludge at 950Jo solids. Combustion of the char and gas is in a fluid bed combustor with an integral boiler for steam generation. Flue gases are fina lly cleaned in a baghouse prior to discharge to the stack. Capital costs for such plants, with nominal capacities of 25 and 50 dry tonnes per day have been developed. Those costs, which exclude allowances for equipment redundancy, amount to $8.2 million for a 25 tpd plant and $11.5 million for a 50 tpd plant. The OFS technology is in direct competition with other thermal based technologies such as incineration. The most reliable costs for sludge incineration developed to date are those reported by Proctor and Redfern, in a stud y of four thermal-based sludge processes in Canada

(Proctor and Redfern, 1987). This study thoroughly reviewed costs at four sludge incineration plants in Ontario, Canada, processing between 36 and 67 dry tonnes of sludge per day. Total annual sludge processing costs, including capital depreciation, varied from $350 to $1042 (Canadian) per dry tonne of sludge processed. Operating costs for these facilities varied from $94 to $375/tonne . Total annual costs for a 50 tpd OFS plant, excluding oil credits, are estimated at $188/ tonne, which is significantly lower than the most cost effective sludge incineration system evaluated in Canada. The OFS process is therefore very cost competitive vis-a-vis incineration. This is due to both lower operating and capital costs. Capital costs are less than equivalent incineration plants, primarily due to the fact that the char combustor is roughly one third the size of an equivalent sludge incinerator. When energy credits for oil sales, at 30 c/L, are factored into the economics, net operating costs for the 25 and 50 tpd plants are $20/ tonne and $ - 5/ tonne respectively.

IMPACT OF THE TECHNOLOGY Thermal conversion of sludge to fuel offers the wastewater industry a number RAW SLUDGE

1

SLUDGE CONDITIONING CONTROLLER

~

2% Solids

ROTARY SLUDGE PRESS DEWATER ING 40% Solids

Steam

--

Flue Gas

t I APCD

i

Ash to Landfill

STEAM DRYER

95% Solids 1'

I_ 1-

BOILER Hot Flue Gas

FLUID BED COMBUSTOR

Char

-4--

Spray Cooling â&#x20AC;˘ of Char

'

r

CONVERSION REACTOR INCG for Reactor Heating

CONDENSER

,,Oil and Water

Water

Combustion Air

Reaction Gases

11

CENTRIFUGE

Foul Process Air Oil PRODUCT STORAGE #2 Fuel Oil (Diesel)

Figure 4. Integrated OFS Plant Schematic.

of potential advantagfS. The first is reduced cost for municipal sludge treatment, as discussed above. The second is an increase in the energy efficiency of sludge treatment systems, not only in the generation of that energy but also its utilization. In the past, it has been standard practise to anaerobically digest sludge and produce methane as a source of energy. The methane was generally used to heat the digesters and to provide heating for the entire physical plant when required . Unfort unately, this approach normally means that significant flaring of the excess metb ,.me occurs in the summer, unless some other means of using the energy is designed into the plant. Another means of recovering energy is to utilize the hot flue gas from sludge incineration to generate steam and ultimately produce electricity. This process is inherently inefficient due to the number of energy transformations whic h are required, ie. from thermal to mechanical to electrical energy. Once the electrical power is generated, a market for it must still be found and local utilities will generally pay only marginal rates for each kwh generated. By comparison, the production of oil by thermal conversion is very energy efficient. The oil is generated in one catalysed thermo-chemical conversion which is much more efficient than transformations between mechanical and electrical energy. In terms of thermal energy, the oil from sludge process is 95 to 980Jo efficient (ie. 95 to 980Jo of the energy in the dried sludge is recovered in the various products). The other major advantage that this process offers is flexibility. The end product can be stored and transported so that the oil cai,. be used on or off site and it can be used only when needed. This factor offers a multitude of ways in which the oil can be utilized for in-plant requirements, other uses within the authority or for sale as diesel fuel. Most large Australian Water Authorities have need for diesel fuel , normally to run stationary diesel generating sets. If the authority can use all the oil produced, avoided costs for purchased diesel fuel, can be credited to the OFS process. Based on the Australian sludge quality data it appears that the OFS technology will be even more energy efficient in Australia. This is due to the high volatile solids content of Australian sludges, which is primarily due to the fact that storm water and sanitary sewers are segregated. Most digested Australian sludges have volatile solids contents above that of raw sludges in North America. This indicates that oil yields for digested Australian sludges should be similar to those achieved with raw North American sludges. The third area in which this technology offers a major advantage is in the overall philosophy of treatment plant design and operation. One of the disadvantages of cost effective high-rate treatment systems has traditionally been the increased sludge production and its associated downstream treatment costs. With conversion, increased sludge quantities will result in increased oil production, thus decreasing processing costs. WATER August, 1988

35


The above discussion is based on the assumption that the construction of a complete new sludge treatment fac ility is required . The conversion process also has the distinct advantage of integration into existing plants in a retrofit mode. For example, a portion of the sludge could be converted to oil to provide fuel to incinerate non-autogenous sludge or an existing incinerator could be used as the char combustor. Although the economic advantages are no t expected to be as dramatic as in the case of a · ' turn-key' facility, the process will significantly reduce sludge management costs and increase flexibility . T he future integration of the oil from sludge technology into the wastewater industry world-wide will be accomplished by J?rivate ownership/ private operation , public ownership/ private operation or public ownership / public operation. The combination of private ownership and operation offers the greatest potential for savings throughout the industry. Where a private enterprise organisation has long term sludge disposal contracts with an authority using agreed ' tipping fee ' rates, profits generated by that orga nisation will be a function of the quantity and quality of oil produced. This approach places operation of the plant into the same context as a chemical process plant which produces a saleable end

BOOK REVIEW

Chapter 5: Groundwater Models, K. R. Rushton, Birmingham, UK. This chapter provides a concise summary of modelling methods and several case outlines to illustrate some of the potential traps for modellers . T hree types of model are considered: Regional groundwater models; Radial flow models; Vertical section models. WATER August, /988

COMMERCIALISATION OF THE TECHNOLOGY Data generated from the CEL pilot plant developmental program in Perth will provide the information required by clients to assess the technical and commercial viability of the OFS technology. T-he pilot pla nt will be available after December 1988 , for site specific trials. Keen interest in the technology has al ready been s hown by the Wal"' Authorit y of Western Austra lia, the Melbou rne and Metropolitan Board of Works, ACT Water and the Mi nistry of Environment, Singapore.

REFERENCES BAYER, E. and KUTUBUDDIN , M. ( 1982) . Low Temperature Con version of Sludge and Waste to Oil. Proceedings o f the International Recycling Congress , Berlin , West German y. BRIDLE, T . R. {1 982) . Sludge Derived Oi l: Wastewater T reatment Implications. ' Env. Tech . Lellers' 3, 151 - 156. BRIDLE, T. R. and CAMPBELL, H. W. (1983). Liquid Fuel Production from Sewage Sludge . Pro-

Continued from Page 9

Chapter 4: Groundwater Flow and Pollution in Fractured Rock Aquifers, Jacob Bear, Haifa, Israel and Brian Berkowitz, Jerusalem , Israel. The authors grapple with this difficult subject using a mathematical approach and giving careful consideration to the use of appropriate methods of analysis, depending on the scale of the problem being analysed . Consideration is given to flow and to contaminent transport in single and multiple fract ures in rock. Special attentio n is given to the case in whic h fractures exist in a porous rock mass. In such cases much of th e fluid flo w occurs in the fractures while significant storage occurs in the porous rock. Contaminant transport is predominantly by advection and dispersion within the fractures and diffusion within the porous blocks. Again this chapter is li kely to be used by researchers and specialists rather than practisi ng hydrogeo logists and engineers.

36

product and where profit is a direct fun ction of process performance and efficiency. These cost savings will be reflected in lower community costs for sewage treatment.

For each type, comments ar made on relevant co n sid e rations · e luding: Recharge estimation ; Nonli earities introduced by cavities in limest ne aquifers, springs and streams; lnflue ce of aquifer layering on well performan e and on well test observations and anal~ is. This chapter is highly re mmended for those interested in gro und ater modelling and in understanding gr und water flow problems. Chapter 6: Groundwate Utilisation and Protection, Ernst P. Austria. A comprehensive des methods for gro un water resource evaluatio n , developme t and protection . Particular attentio n is g ven to water supplies from alluvia l a uifers, there are detailed discussions on : observation wells and production wells i eluding: concrete lined with bottom in ke , spear point wells, drilled wells, h rizontal wells shaft , screens, drilled radially from filters and well develop ent , unconfined aquifer pump test analysis. T his chapter is recom~ ended .for those interested in horizontal (r dial) wells, spring water suppl y dev opment and groundw ater protection . R. FRIDAY, Golders Associ es. Dr. P. VAN DER REIT , Camp Scott Furphy. D. MITCHELL, Camp Scott Furphy.

ceedings of the ENFOR Third Canadian Biomass Liq uefaction Exj'!ert s Meeting, Sherbrooke, Quebec, Canada. BRIDLE, T. R. and CAMPBELL, H . W. ( 1984). Conversion of Sewage Sl udge to Liquid and Solid Fuels. Proceedings 7th Annual AQTE Conferen ce , Montreal, Quebec, Canada. BRIDLE, T. R. and CAMPBELL , H. W. {1986). Process and Apparatus for the Conversion of Sludges . US Patent No. 4,618,735. BRIDLE , T . R. and CAMPBE LL , H . W. (1986a) . Oil fro m Sludge : A Techno logy Update . Proceedings 9t h Annu al AQTE Conference, Mo ntreal, Quebec, Canada. BRIDLE, T . R. et al ( 1987). Evaluat io n of Heav y Metal Leachabili ty from Solid Was tes . 'Wal. Sci. Tech.' 19, 1029- 1036. CAMPB ELL , H . W. nd BRIDLE , T . R. (1985). Sludge Manegoment by Therma l Conversion to Fuels. Proceedings of Co nference, New Directions and Research in Waste Treatment and Residuals Management, Vancouver, Canada . CAM PBEL L, H. W ., BRIDLE, T . R. and LEGAULT, R. ( 1987). Conversion of Sludge to Oil: A No vel Approach to Sludge Management . Presented at the 60t h Annual WP CF Conference, Philadelphia, SA. PROCTOR and RED FERN ( 1987). Development of a Meth odology to Investigat e the Cost Effect iveness of Various Sludge Management Systems, Final Report (DSS-UP-205) to Environment Canada . SHIBATA, S. {1937). P rocede de Fabr icat ion d' une Hui lle Combu stible a Parti r de Boue Digeree , French Patent No. 838,063 . •

~+ t

CLEANING AND DISINFECTI PRACTICES FOR WATERMAI Produced lty the Major Urban Water a d Sewerage Authorities of Australia. $20. ~ Greer, MMBW, GPO Box 4342 Melbourne 3001. (03) 615 5816. The Repo rt , ansmg out of Specialis Workshop No . 2 1, held in Melbourne in November 1987, comprises a series of technical reports on pipeline swabbing practices and techniques, air scouring of water mains and disinfection practices, together with two papers on cleaning and disinfection of water mai ns by the guest speaker, A . Pilling of the North West Water Authority in the UK. Also included is a summary of mains cleaning and mains disinfection practices of 10 authorities represented at the Workshop, covering all major urban authorities and a number of regional authorities . Conclusions arising from the matters under consideration by the Workshop are included as a separate section of the report. There is little reason for doubt abo ut the need for and importance of the water main cleaning and disinfection. The methods employed , particularly where resources are limited , can often leave room for doubt a bout the results achiev ed. T he information contained in 9'1e Report and description of methods J nd res ults should enable any operat91' to evaluate, and perhaps improve, urrent practices and techniques. W. J. DULFER


The Peel Inlet and Harvey Estuary Management Strategy R. A. Gorham, R. Humphries, J. S. Yeates, G. R. Puglisi and S. J. Robinson ABSTRACT The Peel-Harvey estuari ne system, a shallow coastal Iago-on in the south-west of Western A ustrali a, has bec9me eutrophic because of large inputs of phosphorus fro m agriculture in its coastal plain catchment. The resu lting excessive algal grow th in the estuary is a major public nuisance, and is a symptom of the estuary's poor environmental health . Kinhill Engineers Pty Ltd has recently compiled the Stage 2 Environmental Review and Management Program (ERMP) for the Peel Inlet and Harvey Estuary Management Strategy, on behalf of the Department of Marine and H arbours and the Department of Agriculture . The ERMP is the culmination of 10 years of investigation carried out by many agencies into the causes of the problem and possible solutions to it. The Stage 2 ERMP proposes a management strategy consisting of the following five elements: • construction of a new channel between Harvey Es tuary and th e ocean; • continuation of fertilizer modification practices currentl y recommended to farmers by the D epartment o f Agriculture; • implementation of stricter catchment manage ment measures; • changes in land use; • continuation of macroalgal harvesting. This paper summari zes the proposed management strategy and the predicted environmental impacts of the proposals.

INTRODUCTION The Peel-Harvey estuarine system (the estuary) is a shallow coastal lagoon of approximately 133 km 2 , 70 km south of Perth, Western Australia (Figure 1). The estuary is eutro phic, and for the past 15 years has experienced excessive growths of algae in the water. The accumulation and decomposition of the algae, particularly on the shores adjacent to residential areas, have caused severe public nuisance. The excessive grow th of algae is indicative of serious deterioration in the environment of the estuary. In 1976 the Environmental Protection Authority's Es tuarine and Marine Advisory Committee initiated investigations into the algal nuisance. It has taken 10 yea rs of research to pin-point the source of the problems, and to propose effective management measures. The Stage 2 Environmental Review and Management Program (ERMP) for the P eel Inlet and Harvey Estuary Management Strategy has recently been compiled by Kinhill Engineers Pty Ltd (1988), on behalf of the Department of Marine and H ar bours and the Depar tme n t of Ag ri culture. The Stage 2 E RMP is the res ult of the research into the algal problems of Peel Inlet and Harvey Estuary.

R. A. Gorham

R. Humphries

J. S. Yeates

G. R. Puglisi

Richard Gorham is Senior Environmental Scientist with Kinhill Engineers Pty Ltd in Perth, and was the principal author of th e Stage 2 Environmental Review and Ma nagement Program (ERMP) for the Peel Inlet and Harvey Estuary Management Strategy. Richard is a marine ecologist with eight years' consulting experience in marine and aquatic environmental impact assessment and the preparation of environmental management programs. Dr Bob Humphries is the Manager of the Estuarine Impacts Branch of the Environmental Protection Authority in Western S. J. Robinson Australia. Bob has been associated with the Peel-Harvey investigations since 1977, and is a co-author of th e management strategy proposed for the estuary in 1984. He has managed the Estuarine Impacts Branch since late 1985. Dr John Yeates is currently R egional Manager of the Western Australian Department of Agriculture's No rthern Agricultural R egion, based in Geraldton. Between 1978 and 1987 he worked as a plant nutritionist, with (after 1982) a particular interest in agriculturally caused eutrophication of water bodies in the south-west of Western A ustralia. In that role, he co-ordinated the Department of Agriculture's Peel-Harvey Study program, and worked closely with Kinhill Engineers Pty Ltd in th e preparatio{l of the Stage 2 ERMP. Rob Puglisi is the Manager of Environmental Studies with Kinhill Engineers Pty Ltd in Perth, and was the Study Ma nager for the Stage 2 ERMP1for the Peel Inlet and Harvey Estuary Management Strategy. Rob is a civil engineer with extensive experience in the preparation of environmental management programs and environmental approval documentation. Sally Robinson is a Senior Environmental Officer with the Environmental Protection Authority. She has had seven years of en vironmental impact experience and is the leader of the Environmental Protection Authority's Peel In let and Harvey Estuary Stage 2 ERMP assessment team. (e .g. Hodgkin et al 1980; Humphries and Croft 1984; Hodgkin et al. 1985; PeelHarvey Study Group 1985). The earlier Stage 1 ERMP (Peel-Harvey Stud y Group 1985) addressed the various alternative management options and proposed a recommended management strategy designed to effect a long-term solution . T his was assessed by the Environmental Protection A uthority in 1985, and its assessment report proposed management objectives for the estuarine system and that a detailed Stage 2 ERMP should be prepared . The Stage 2 ERMP addresses in detail the proposed management strategy and its environmental implications. This paper summarizes the proposed management strategy and the predicted environmental impacts of the proposals.

NATURE OF THE PROBLEM T he algal problem in Peel Inlet dates from the mid-1960s, when large amounts of weed were beached, where they decomposed and caused foul odours. The algae also caught in the nets of fishermen and

tangled boat propellers . The algal problem is generally considered to have reduced to urism and recreational enjoyment of the region and may have caused some red uction in property values. The nuisance has been reduced in part by the weed harvesting program, but the cause of the problem st ill remains. Weed harvesting has cost well in excess of $ 1 million over the last 13 years . Initially, the major nuisance was caused by an algae called C/adophora, or goat weed, but other species, for example rope weed (Chaetomorpha) are now more abundant. In 1973, the problem intensified dramatically with the first largescale bloom of the blue-green microalgae Nodu laria, in Harvey Estuary . Nodularia blooms have subsequently occurred in Harvey Estuary in 1974 and 1978 and then throughout the whole Peel-Harvey system every year from 1980 to 1986. Nodularia blooms did not occur in 1987, because the total river inflow (and hence phosphorus input) was very low because of the low winter rainfa ll. The dry winter also meant that the salinity of the water in the WATER August, /988

39


WESTERN

main target for management. FurtherlJ!Ore, Nodu laria is a nitrogen fixer and exploits periods of nitrogen deficiency when it becomes dominan t. Control of nitrogen availability would not control

AUSTRALIA

GERALOTON

Nodularia.

Figure 1. Location map showing extent of catchment.

estuaries remained too high for the germination of Nodu laria in spring. Nodularia is positively buoyant and planktonic, and distributes throughout the water column, turning the water green. In calm weather, it floats to the surface and forms a thick scum, which drifts ashore and breaks down . This causes the release of a peculiar nauseating smell , which causes great discomfort and possible ill-health to people living near the beaches. Nodularia in the water can clog fish gills and reduce oxygen levels so much that, at times , large numbers of fish, crabs and other fauna are killed. The algal problem in the estuary is indicative of a critically imbalanced ecosystem. Should this imbalance continue, further deterioration of the health of the system will occur. Although it is difficult to define the urgency of the problem from a biological point of view, it is beyond question that the estuary is presently in an unsatisfactory condition and that further deterioration will make any eventual recovery significantly more difficult, or even impossible.

CAUSES OF THE PROBLEM The Peel-Harvey System is a broad, shallow waterbody with strongly seasonal (winter) river inflow , and very limited oceanic exchange. These features favour a highly productive system, naturally 40

WATER August, 1988

predisposed to eutrophication (Hodgkin 1980; Hodgkin et al. 1985). However, human activities in the catchment (e .g. clearing, drainage and various agricultural land uses) have rapidly increased the rate of input of nutrients to the system, and therefore the frequency and intensity of the algal blooms. The nutrients nitrogen and phosphorus are both essential to plant growth, and a shortage of either can limit the size of the algal crop. However, it is generally phosphorus, rather than nitrogen, that is the 'limiting nutrient' to algal growth in the estuary. Therefore, phosphorus is the

et al.

For the past several decades, the estuary has received high phosphorus loadings from runoff from agricultural land in the catchment's coastal plain, i.e. to the west of the Darling Scarp. Although the coastal plain is only 180Jo of the greater catchment and contributes less than half of the total stream flow, it contributes about 900Jo of the annual phosphorus load to the estuary. Most of the phosphorus load to the estuary is derived from applications of superphosphate on pastoral land. More recently, there has also been a substantial and in creasing contribu tio n of phosphorus from intensive agricultural activities in the Serpentine Ri ve r catchment. Table I sho\ s the estimated contributions of phosphorus to the estuary from broad-scale agri culture, or 'diffuse' sources, on the three broad soil classes that occur in the coastal plain catchment, and from intensive agricultural activities, or 'point' sources of phosphorus pollution . These figures highlight the relative importance of the highly leaching deep grey sands, wh ich contribute half of the total p hosphorus load yet form only 240Jo of the catchment's cleared area. Intensive agricultural activities similarly contribute a large phosphorus load from few sources; for example , monitoring in 1986 confirmed that about 350Jo of the total Serpentine River phosphorus load was derived from one large piggery and two sheep holding yards alone. Average ,annual phosphorus inputs from the catchment to the estuary are more than twice the amount that is annually flushed out of the channel to the ocean at Mandura h . As a resu lt, large amounts of phosphorus have accumulated in the estuary's sediments, and a considerable proportion of this releases as soluble phosphate when the sediments become anoxic. Phosphate is readily assim ilated by aquatic plants and stimulates the nuisance blooms of algae. The estuary's sediments have now become a major source of biologically available phosphorus to algae, complementing the external (river) sources.

Table 1. Estimated contributions to the Peel-Harvey system's mean annual phosphorus loading (1977-1986) Source

Estimated phosphorus lossesâ&#x20AC;˘ (tl a)

Estimated phosphorus export rates (kg / ha/ a)

Estimated contribution

14 36 72

0.35 0. 5 2.0

10 25 50

from 40 ,300 ha from 73,600 ha from 36,300 ha

Total diffuse sources Losses from point sourcest

122 21

0.8

85 15

from 150,200 ha virtually a ll to the Serpentine Ri ve r

Total

143

0.95

100

Losses from board-scale agr icultural land: loams, clays and fert ile sands sand over clay so ils deep gre y sand so ils

Co mments

%

â&#x20AC;˘ Based upon mea n an nual phosp horu s load of 143 t. t Based upon measured losses of 14 t from pi ggeri es an d sheep holdi ng yards, with an es 1imated addit ional co ntribution of 7 t from mark el ga rd ens and other point sources. Th e con 1ribution from mark et gardens has increased substa ntially during recent years.


Harvty RIHr and drains 140

·' / 11

120

-

120

. oo /': !Y

V

12

100

,,,.

40

1/ v.11

20

V

/ I

1/

100

V

./

80

60

;/ 1/. ".

80

150

., / 71

u':%

40

20

100

200

- ~~

~~ -

60

/

50

would continue to support algal growth for some years with,he existing regime of restricted water exchange with the ocean. The input of phosphorus cannot be stopped; it can be reduced, but not by an amount sufficient to prevent continuation of algal blooms for a long time, probably in the order of 20 years. In order to return the estuary to a clean, healthy and resilient condition , it is necessary to: • red uce phosphorus inputs from the coastal plain catchment from the existing avern.ge of 143 t/ a to a maximum of 85 t/ a; • substantially increase the water exchange with the ocean.

S.rpen tine River

300

250

v

.

Z.•"

l/

/ " I

350

50

V

I I 100

150

200

250

300

:.:o

Streamflow (ml x 106)

S1reamllow (ml x 106)

THE PROPOSED STRATEGY

Mu"ay River 100

80

L---

'; 20

~ 50

.

M

_..I!

i----

~

.

:.--- ~

------.Y.-L.----_.___

l

'

L.----- i----

.

Ii

11

100 S1reamllow (ml x 106)

Figure 2. Streamflow and phosphorus loading in each catchment 1977-86.

The ecological regime that currently exists in the estuary efficiently induces high release rates and rap id recycling of phosphate from the sediment phosphorus store when growing conditions are optimal. T he initiation of Nodu laria blooms, now an ann ual event in Harvey Estuary, is coincident with high phosphate release from deoxygenation at the sediment surface as earlier blooms of diatoms die and decay. In Peel Inlet, the predominant weed species grow over the sediment surface and efficiently induce their own regime of deoxygenation and phosphate release. Without suitab l e management measures, nutrient enrichment of the estuary will increase, with resultant exacerbation of the algal problem. For the last 10 years, below-average rainfa ll and river fl ow have caused red u ced phosphorus loads to the estuary (Figure 2). With a return to a more normal rainfa ll regime and with increasing pressure for development of the catchment area, the condition of the estuary will deteriorate further unless phosphorus loads are controlled.

resulting in the storage of a substantial bank of biologically available phosphorus in the sediments. Even if all phosphorus input to the estuary could be stopped, phosphorus recycled from the sediments

About 120 poss ible management measures were evaluated by Humphries and Croft (1984), and the most promising combinatio n was proposed . Additional evaluation of these measures since public release of the Stage 1 ERMP in August 1985 has supported the recommendations of Humphries and Croft (Peel-Harvey Study Group 1985) . The proposed management strategy comprises the fo llowing elements: • catchment management - to red uce the input of phosphorus to the estuary; • construction of a new channel to the ocean near Dawesville (Figure 3) - to increase the water exchange with the ocean, thereby reducing the biologically available phosphorus in the estuary; • weed harvesting - to alleviate the effects of weed accum ulations on residential areas.

MANAGEMENT OBJECTIVE T he objective of the management strategy is to return the Peel-Harvey estuari ne system to a clean, healthy and resilient condition (Environmental Protection Authority 1985). The present condition of the estuary fa lls far short of this. The o bj ective can only be achieved by reducing the levels of nutrients, especially phosphorus, available to algae in the estuary. For the past several decades, the input of phosphorus to the estuary has been much greater than the loss to the sea,

t N

Figure 3. Peel Inlet and Harvey Estuary, showing location of the proposed Dawesville Channel. WATER August, 1988

41


Implementation of both the catchment management strategy and the Dawesville Channel proposal is considered essential to the achievement of the management objective for the estuary. The proposed catchment management measures have the potential to greatly reduce phosphorus losses to drainage, especially from agriculture on highly leachin g sands and from intensive agriculture . The proposed Dawesville Channel would more than double water exchange with the ocean , thus: • greatly increasing the export of phosphorus from the estuary, thereby reducing the phosphorus available for algal growth : , • co nverti ng tne estuary to a more marine environment, there by improving its ecological resiliance; • creating a more saline environment that would be un favo urable for Nodularia growth . Without the Dawesville Channel, much more strenuous catchment management measures would be required in order to achieve the manage ment objectives. Because the biologically avai la bl e phosphorus in the estuary wo uld be redu ced extremely slowly by flu shing through the existing Mandurah Channel, algal blooms would continue for a considerable period of time (at least 20 years). There is also the risk that the condition of the estuary would deteriorate further before the catchment management measures were effective, which wo uld make any eventual recovery significantly more difficult. The management measures would take several years to be fully effective in reducing the phosphorus that is available for algal growth in the estuary . In the meantime, the annual nuisance from weed growth would continue, and would increase for a few years in the clearer estuary water fo llowing channel construction, as light limitation of algal growth was reduced. Therefore, continued and upgraded weed harvesting of nuisance algae is a necessary part of the proposed management strategy.

Modification of agricultural fertilizer practices

Moratorium on further clearing and drainage

The principal; immediate catchment management measure is the red uction of phosphorus inputs to the estuary by encouraging farmers to adopt appropriately modified fertilizer techniques. The successfu l implementation of this strategy to date demonstrates its practicability, and has shown that farmers can make significant savings in the cost of fertilizers by modifying present practices (Yeates 1988). It is proposed that the currently implemented fertilizer management strategy continue. This strategy involves: - advice to farme rs on fertilization regimes, based on accurate assessment of ferti lize r requireme nts by paddockspecific soil tests; - the use and further development of individual-nutrient ferti lizers, especially a spreadable form of sulphur. Co-ordination and integration of the strategy by the Western Australian Department of Agriculture would continue, and the strategy would be monitored as necessary. An incentive scheme may be required, to overcome economic constraints to manufacturers producing new fertilizers and to farmers using them.

The great increase in phosphorus input to the estuary between the 1950s and 1970s is attributed to the increased use of superphosphate fertilizer and, since about 1960, to the clearing, drainage and cultivation of highl y leaching deep grey sands on the coastal plain (Birch 1982). 1t is proposed that there be a moratorium on further clearing and drainage until policies and guidelines for future land clearing and drainage are developed . Such policies should take into consideration the success of the management techniques for exisrlng ·clea~ed land.

Co nversion of land use to forestry Conversion to forestry of agricultural land on sandy soils provides a means to substantially reduce phosphorus loadings to the estuary in the long term. Preliminary economic evaluation shows that this measure warrants large-scale field trials to test its technical and economic practicability (Shea and Bartle 1988). Large-scale trials will be undertaken in the winter of I 988 to ascertain the potential of converting use of the sandy soils from agriculture to forestry, and to measure the reduction of phosphorus losses from la nd under plantations. Depending on the resu lts of feasib ility studies, a realistic objective would be to encourage conversion to forestry of up to half the presently cultivated land on highly leaching sands of the coastal plain catchment.

Catchment management T he investigations have demonstrated that the deterioration of the estuary is caused by current land uses in the catchment, especially the fertilization of highly leaching sandy soils for farming. Land uses that cause high nutrient losses to drainage are incompatible with the environmental capability of the catchment land. The proposed catchment management strategy matches land use practices with land capability, so that agriculture can be sustained with mm1mum phosphorus losses. The strategy ai ms to achieve its objectives in a manner which is both socially and economically acceptable. It is proposed that high priority be given to the preparation and implementation of a detailed catchment management plan, which should include the measures discussed below. 42

WATER August, 1988

Control of point sources Piggeries, sheep holding yards and market gardens are major sources of phosphorus to the estuary and hence an important component of catchment management (Humphries and Bott 1988) . It is proposed that further expansion of intensive agricultural activities within the Peel-Harvey catchment shoµl d only be permitted subject to stringent restrictions on nutrient loss to groundwater and to surface drainage. Investigation of practical and costeffective waste management strategies is in progress, and an economic framework for their implementation will be prepared, in co-operation with producers. This would require a negotiated compromise between technical feasibility and economic practicality.

'

'

The Dawesville Cha nnel Construction of the proposed channel between Har ey Estuary and the ocean is fundamental to achieving the aims of estuary management within an acceptable time-scale and with the least stringent catchment control. The channel would substantially increase water exchange with the ocean, decreasing the phosphorus available for algal growth and making the estuary a more marine system. The proposed engineering of the channel is described in detail in the report by the Department of Marine and Harbours (1987). The channel wo uld vary from 150 m to 200 min width and 4.5 m to 6.5 min depth, and wo uld be constructed using conventio nal earth-moving equipment and cutter suction dredges. Disposal of spoil material woukl be in accordance with identified objectives for recontouring adjacent land. It is proposed that the Dawesville Channel be constructed as soon as is practicable.

Control of weed accumulations Following implementation of the proposed management strategy, it would be several years before biologically available phosphorus was sufficiently reduced to eliminate the excess weed growth and its accumulation on the shores. Weed harvesting would need to continue during this period , and it may be necessary to increase the capacity of weed harvesting operations in order to keep the beaches reasonably free of weed. It is anticipated that, in the longer term, the proposed ma nagement strategy would remove or greatly decrease the need to harvest weed . It is proposed that the existing weed harvesting operations continue, and be extended where necessary. Methods of improving the efficiency of harvesting operations warrant furt her evaluation, as do other measures to control weed growth and accumulation (e .g. the use of algicides).

PREDICTED OUTCOME OF THE PROPOSED STRATEGY The predicted outcome of the proposed management strategy is summarized as fo llows in terms of the reduction in phosphorus input to the estuary, the


reduction in the biologically available phosphorus in the estuary, and the consequent amelioration of the algal nuisance. Other predicted impacts of the sttategy are also briefly discussed.

Reduction of phosphorus inputs from the catchment Diffuse sources It is predicted that the fertilizer management strategy would achieve a maximum reduction of 30% in phosphorus loss from agricultural land, compared with pre-1983 Tosses, if all farmers applied only the amount of phosphorus required to optimize production in the long term. Broad-scale agriculture currently _ contributes an estimated 122 t of the average 143 t/ a of phosphorus to the Peel-Harvey estuary. Of the 122 t, approximately 108 t come . from the sand y soils of the catchment. The potential reduction in phosphorus load to the estuary that could be achieved by implementation of the fertilizer management strategy on 75% of the cleared, sandy catchment soils would be 24 t/ a, or 32 t/ a with 100% adoption. In the long term, conversion of half the agricultural land on leaching sands to forestry would reduce phosphorus losses by about 30 t/ a, in addition to the reduction achieved by the fertilizer management strategy. That is, the combination of the fertilizer management strategy and conversion to forestry would reduce the currently observed annual average phosphorus load to the estuary (143 t) to about 85 t/ a, the minimum target for management.

Point sources Point sources currently contribute an estimated 21 t/ a of phosphorus to the estuary, mainly via the Serpentine River. Planning and management are essential to the substantial reduction of phosphorus losses from existing sources and the control of new sources, and would be implemented under the provisions of the Environmental Act, 1986.

Reduction of biologically available phosphorus in the estuary Though difficult to accurately predict, construction of the Dawesville Channel would lead to a marked decrease in biologically available phosphorus in the estuary, through: • greatly increased direct flushing of phosphorus through the estuary to the ocean; • reduction in the size and duration of winter diatom blooms, which would reduce the amount of phosphorus accumulating in the sediment store for subsequent recycling; • lower the intensity of diatom blooms, which would reduce the organic carbon loading to the sediments. This would reduce the frequency and extent of deoxygenation at the sediment surface, and phosphorus release to the water column; • reduction in the rate of phosphorus release from the sediments, because of the

greater inflow of oxygenated marine water. This effect would be greatest close to the Dawesville Channel. Annual average export of phosphorus through the existing Mandurah Channel is estimated to be about 60 t. Mathematical modelling indicates that the volume of water exchange through the proposed Dawesville Channel would be three times the present water flow through the Mandurah Channel. It would also have the effect of increasing flow through the Mandurah Channel by some 15-20%. Simple flushing models of the estuary after construction of the Dawesville Channel show that the water residence time in the est uary would be h a lve d . Total phosphorus export from the estuary should at least double immediately fo llowing construction of the Dawesville Channel, but would decline as the concentration of phosplic,rus in the estuarine water was reduced with time .

Effect on the algal nuisance Nodularia blooms Construction of the Dawesville Channel would dramatically alter the salinity regime in Harvey Estuary, substantially shortening the growin g season of Nodu laria, which does not grow in salinities exceeding 30 p .p .t. (Huber 1985) . Massive Nodularia blooms would no longer occur , except perhaps in years when above-average rains late in the season maintained low salinities in the estuary well into the spring. When blooms did occur, they would be of lower intensity and of shorter duration than those of recent years .

Macroalgal blooms The growth of macroalgal weed would not be reduced immediately, and would increase in the initial years following channel construction. It is likely that high productivity of large green algae would be maintained until the biologically available sediment phosphorus was substantially reduced. Meanwhile, these algae would cause continued fouling problems in Peel Inlet, possibly reaching the high levels experienced in the late 1970s, and may spread to Harvey Estuary. It is difficult to predict how quickly the biologically available phophorus in the estuary's sediments would be reduced sufficiently to cause a decline in weed growth. However, in time, after construction of the Dawesville Channel, nuisance weed growth would reduce to acceptable levels .

Secondary environmental impacts The Dawesville Channel would force a radical shift in the estuarine environment towards a more marine ecosystem, and would also cause complex changes unrelated to the algal problems .

Secondary environmental impacts of the Dawesville Channel A detailed discussion of the probable secondary impacts of the proposed

Dawesville Channel is not possible in this paper and the reader is referred to the Stage 2 ERMP (Kinhill Engineers Pty Ltd 1988). The following is a summary of the main points : - Tidal regime: The normal daily tidal range would increase from about 0.1 m to about 0.3 m, with a maximum of about 0.35 m. The duration of flooding and exposure of the tidal flats would be shorter than at present. - Water quality : The estuary would generally be clearer because of the reduction in microalgal blooms. Enhanced mixing of the estuary water fr om increased tidal movement, plus a reduction in organic matter in the sediments, would improve the aeration of bottom waters. - Biology: The present biota \n the estuary is adapted to extreme environmental conditions, and the Dawesville Channel is not expected to have an y major adverse effect on it. The biological community in the Peel-Harvey estuary has already been considerably modified during recent years, and further changes would occur in response to the altered physical environment. - Recreational use : The Dawesville Channel should greatly improve the long- term attractiveness of the estuary for recreational use. However, an initial decrease in amenity is likely, especially in Harvey Estuary, because of the predicted increase in macroalgal growth in the first few years after construction . The Dawesville Channel would offer attractions for recreational use similar to those of the Mandurah Channel. - Commercial fishery: Conversion of the estuary to a more marine ecosystem would encourage a greater diversity of fish species, but might reduce the numbers of some fish cufrently sought by commercial fishermen. For example, it is anticipated that numbers of yellow-eye mullet, cobbler and tailor , and especially marine species such as whiting and mulloway, would increase, but sea mullet would decrease. Blue manna crabs might spend longer in the estuary than at present, but king prawns, and perhaps the greasyback prawn, might be less abundant because of the lower summer salinities. The overall extent to which the viability of the commercial fishery would be affected is difficult to predict. - Mosquito nuisance: There would be an increase in breeding opportunities for saltwater mosquito species in some areas, because of the altered tidal regime. This aspect would need further investigation following a commitment to construct the Dawesville Channel. Emphasis should be placed on physical control methods in breeding areas, and regional methods to kill both adult mosquitoes and larvae. This is presently beyond the resources of the responsible local authorities. - Construction impacts: Construction of the channel would destroy vegetation along its route and in spoil disposal areas, including the fringes on the nearby shores of Harvey Estuary. Rehabilitation of the reclaimed area would be required. It would also be necessary to undertake a detailed survey of the development area, to identify, assess and offer protection to possible aboriginal sites. WATER August, 1988

43


Secondary environmental impacts of weed control Weed harvesting by front -end loaders collects beached algal accumulations and causes some loss of sand and fr inging vegetation. Subsequent erosion has caused a retreat of the shoreline in some areas. Rehabilitation of these areas may be required to prevent extensive retreat of the shoreline.

Secondary environmental impacts of catchment management Significant adverse environmental impacts are not anticipated as a result of implementation of the catchment management measures, but some social and economic adjustment would be necessary following the introduction of large-scale forestry .

CONCLUSIONS The excessive a lgal growth in the PeelHarvey estuary is a soure of considerable public nuisance, and is symptomatic of the estuary's poor environmental health . This has undoubtedly reduced the recreational and commercial attractiveness of the Mandurah region, which is intimately linked with the estuary. The demand for the estuary's recreational amenity will increase as pressures on natural recreational resources near Perth increase, and will only be met by returning the estuary to an 'acceptable ' state. Because the PeelHarvey estuary is recognized as an invaluable asset, it is necessary for the whole community to meet the objective of the proposed management strategy : to return the estuary to a health y and resilient ecosystem. Peel-Harvey estuary, like the Swan River in Perth, should be a healthy estuarine system at the centre of a thriving community. Implementation of the proposed management strategy would achieve a substantial reduction in the phosphorus available for algal growth from the enriched sediments of the estuary, as well as a

reduction in the river-borne phosphorus entering the estuary. The combinatio n of these two measures is a practical way of returning the estuary to a healthy condition with acceptable levels of algal growth.

HODGK IN, E. P., BIRC H , P. 8. , BLACK, R. E . and H UM PHRI ES, R. 8. ( 1980). The PeelHa rvey est uarine system st ud y ( 1976- 1980). Report No. 9. Pert h: Department of Conservation a nd Environ ment. HO DGK IN , E. P., BIRCH, P . 8., BLACK , R. E. and HIL LMAN, K. (1985). The Peel-Harvey estuarine system - Proposals for management. Report No. 14. Perth: Department of Conserva-

ACKNOWLEDGEMENTS

H UBE R, A. L. ( 1985). Factors affecting th e germination of ak in etes of Nodularia spumigena (Cyanobacteriaceae). Appl. Env. Micrabiol. 49: 73-78. HUMPHRIES , R. 8 ., and BOTT, G. ( 1988). Intensive animal industries on the Swan coastal plain and their assoc iated pollution prob lems. In The Swan coastal plain in cri sis - agricul ture and the environment. Proceedings of a forum organized by t he Au stralian Institute of Agricultura l Science to examine land use and environmental problems on the Swan coastal plain, held at Technology Park , Bent ley, March 1988. AIAS Occasional Publication o. IO. Pert h: Western Australian Branch, Australian Ins titute of Agricult ural Science. H UMP HRIES , R. B. and CROFT, C. M. (1984). Management of the Peel-Harvey estuarine system. Report No. 3: Final report . Bulletin No. 165. Perth: Department of Conservation and Environment. KINHILL ENG INEERS PTY LT D (1988). Peel In let and Harvey Estuary management strategy. Enviro nmental review and management program Stage 2. Perth: Department of Marine and Harbours; Department of Ag riculture . PEEL-HARVEY STU DY GROUP (1 985). Peel Inlet and Harvey Estua ry management strategy. Environmental review and management program. Stage 1. Perth: Depa rtment of Conservation and Land Management. SH EA, S. R. and BARTI.. E, J. R. ( 1988). Restoring natures balance: the potential for major reforestation of South Western Australi a . Landscape 3(3): 3- 14. Perth: Department of Conservation and Land Management. YEATES, J . S. ( 1988). Using and losing phosphorus and nitrogen on coastal plain soi ls. In The Swan coastal plain in crisis - agriculture and the environment. Proceedings of a fo rum organized by the Australian Institute of Agricu ltural Science to exam ine la nd use a nd en vironmental problems on the Swa n coasta l plain, held at Technology Park, Bent ley, March 1988. AIAS Occasional Publication No. 10. Pert h: Western Australian Bran ch, Australian Inst itute of Agricultu ral Science. •

The Stage 2 ERMP for the Peel Inlet and Harve y Est u ary Manage ment Strategy was prepared by Kin hill Engineers Pty Ltd for the Department of Marine and Harbours and the Department of Agriculture in Western Australia. Assistance was provided by officers of the Department of Marine and Harbours for aspects of the proposal relating to the Dawesville Channel , and by a Steering Committee convened by the Department of Agriculture for the catchment management proposals. The Steering Committee included Dr John Yeates and Dr Bob Humphries, two of the autho rs of this paper, and Mr Max Poole of the State Planning Commission. The bulk of the information used in the compilation of the ERMP was provided by officers of the Department of Marine and Harbours, the Department of Agriculture, the Environmental Protection Authority and the Department of Conservation and Land Management.

REFERENCES BIRCH, P. 8. (1982). Phosphorus export from coastal plain drainage to the Peel-Ha rvey estuarine system , Western Au strali a. Ausr. J. Freshwater Res. 33: 23-32 . DEPARTMENT OF MARINE AND H ARBO URS (1987). Peel Inlet a nd Ha rvey Estuary management strategy - Dawesville Channel engineering in vestigations. Perth: Department of Marine and Harbou rs. ENV IRONMENTAL PROTECTION AUTHOR ITY (1985) . Report and recommendations by the Environmental Protection Authority. Assessment report of Stage 1 ERMP. Bulletin No. 243. Perth: Department of Conservation and Environment.

tion and Environment.

ALLEN J. GALE

W. DAVID WOODHEAD and S. N. TUCKER

Continued from page 25

Continued from page 30

REFERENCES CONCLUSION The strongest argument for reuse of water is the financial benefit to be gained from reduced water intake and efflu ent discharge . Consequently, water use and effluent disposal must be considered technically and economically as an integral part of the production process. With the growing emphasis on environmental protection, there will be increasing restrictions of the waste disposal practices adopted by industry, with a resultant movement towards waste minimisation and product recovery. This will inevitably result in increased water reuse . It is clear, therefore, that there will be an increasing trend towards water reuse in the resources industry. Not only will this assist in providing a clea ner environment, it will also prove to be an economical course to follow. • 44

WAT E R August, 1988

NATIO NAL COUNCIL ON PUBLIC WORKS IMPROVEMENT (1986). T he Nation's Public Work s: Defi ning the Issues. Washington D.C. NE ILSON ASSOCIATES PTY LTD (1987). Ne t Comm unit y Benefits of Urba n Consolidation. Report prepared fo r the City of Melbourne, Canberra. NIC (1986) . INFACT Newsletter (May) . National Infrastructure Committee (Australia). SOUTH AUSTRALIAN PARLIAMENTARY PUBLIC ACCOUNTS COMMITTEE (1987a). Water Suppl y a nd Sewerage Disposal Asset Replace ment. Fifty-first Report, Government Printer, Adelaide. SOUTH AUSTRALIA N PARLIAMENTARY PUBLIC ACCOUNTS COMMITTEE (1987b). Summary Report on Asset Replacement. Fifty-t hird Report, Government Printer, Adelaide. THOMPSON, J ., DELANE Y, J ., MARKSJO, 8 ., S HARPE, R ., GRANT, A., RAIMONDI , D. and PRIOR M. (1987). An expert system to give advice to operators of a metropo litan water suppl y, drainage and sewerage network. Proc. A ustralian Joint Artificial Intelligence Conference, AI87, Sydney. TUCKER. S. N. ( 1987). Life cycle costing of buildings. Proc. Facilities Management '87 Conf. Natio nal Committee o n Rationalised Building, Melbourne, pp. 57-64 .

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Water Journal August 1988  

Water Journal August 1988