Water Journal June 1991

JUNE 1991

AUSTRALIAN WATER & ½/f\S'fEWATER ASSOCIATION

ANNO QUINQUAGESIMO QUARTO

VICTORl,AJ

REGINJE.

.............................................................

No. MCXCVII. An Act to provide for the better Local Management of the Metropolis and for the creation of a Melbourne and Metropolitan Board of Works.

[20th D ecember, 1890.J

BE

it enacted by the Queen's Most Excellent Majesty by and with the advice and consent of the Legislative Council and the Legislative Assembly of Victoria in this present _Parliament assembled and by the authority of the same as follows (tLat ,e to say):1. Thie Act may be cited as the Melbourne and Metropolitan Board of Work, Act 1890.

CENTENARY

)if~

A~~d!

• WERRIBEE; CUSTOMERS; DEMA D • MELBOURNE WATER AUTHORITY

ALICE SPRINGS AQUIFER EFFLUENT FILTRATION

ISSN 0310-0367

water

Volume 19, No. 3, June 1991

AUSTRALIAN WATER & WASTEWATER ASSOCIATION

CONTENTS My Point of View ............................................... 3

Alice Springs - The Mereenie Sandstone Aquifer P. B. Jolly, G. W. Prowse and D. N. Chin .. 36

rAWPRC News

12

Technical Notes Energy Requirements for PVC and Ductile Iron Pipe ........................................

Wastewater Disinfection by Ultraviolet Radiation ................. .......... .. ... ..

A Worker Friendly Personnel System ......

Urraween lnground Reservoir Project ......

Industry News

14

Plant, Products, Equipment .. .... ... ... .. .... ....... .. 40

President's Message ......................................... 4 It Seems to Me ........... .................................... .. . 5 Association News .............................. ........ ..... ... 6

The Relief of Smellbourne ........................ 15 Melbourne Water Corporation .................. 17 Pictorial Browsing at the Board ............... 18 The Yarra River Conference . ................ ........... 20

22

Water Demand Management in Melbourne H. P. Duncan ...... ......................................... 26 Customer Service - The Board of Works Experience ............. ................ .......................... 30 Application of Deep Bed Filtration in Tertiary Wastewater Treatment S. Vigneswaran .......................................... 32

FEDERAL SECRETARIAT PO Box 388, ARTARMON NSW 2064 Telephone (02) 41 3 1288 Facs im i le (02) 41 3 1047 Office Manager - Margaret Bates

FEDERAL PRESIDENT Peter Norman Telephone (08) 226 2249

EXECUTIVE DIRECTOR Pet er Hughes Telephone (02) 41 3 1288 Facsimile (02) 948 1746

FEDERAL SECRETARY Greg Cawston Telepho ne (042) 29 0236

FEDERAL TREASURER John Mollo}' Telephone (03) 615 5991

BRANCH SECRETARIES Canb er ra, ACT Peter Cox PO Box 306, Woden 2606 (062) 498 522 New South Wal es David Hope, PO Box 460 , Chatswood 2057 (02) 269 5212

42 42 43

Conference Calendar ........ .... .... .... .. ..... ...... ..... 44

Board of Works Centenary Feature

The Werribee Treatment ComplexAn Environmental Perspective A. J. Bremner and A. W. Chiffings

38

OUR COVER An aerial photograph of the lagoons and part of the irrigated land of the Werribee Treatment system of th e Melbourne Board of Works, 40 km. south west of the city. Designed by Mansergh in 1891, border check irrigation by raw sewage during the pasture growing season, backed up by ¡~-....... overland gra ss filtration in the winter, was first used in 1897, and has operated successfully for nearly 100 years. It took nearly 40 years before the load had increased to the stage that the lagoon system had to be installed to deal with peak flows, and a further 30 years before 40 % of the city's sewage had to be diverted to the South Eastern Purification Plant.

(Ph oto by courtesy of th e Board of Works)

South Aust ralia Rob Townsend .

Cl- Stale Water Laboratories .

E&WS Private Mail Bag , Salisbury 5108 (08) 259 0244 Weste rn Aus tra lia Steve Gibson CMPS. 200 Adelaide Terrace Perth 6000 (09) 325 9366

Vi ctoria Joh n Park Cl- Water Traini ng Centre.

PO Box 409, Werribee 3030 (03) 741 5844

Tasm an ia Annelle Nichol GPO Box 503E Hobart 700 1 (002) 28 2757

Qu eensland Don Mackay, PO Box 412, West End 4101 (07) 840 4844

Northe rn Terr ito ry Li ndsay Monteith PO Box 35 1 Darwin 080 1 (089) 81 5922

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

ADVERTISING Ann Sykes-Smith Applta , 191 Royal Parade, Parkville 3052 (03) 347 2377 Fax (03) 346 1206

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

PUBLICATION Water is bi-monthly. Nominal distribution tim es are th e third weeks of February, April, June, Au gust, October, December

IMPORTANT NOTICE The views expressed by th e contributors are not necessaril y endorsed by the Au stralian Water and Wastewater Associ ation. No reader should act or fai l to act on the basis of any materi al contained herein . No responsibility is accepted by th e Association,. the Editor or the contributors for the accuracy of informati on contained in th e text and adverti sements.

The Au stralian Water and Wastewater Association reserves th e right to alter or to omit any article or adverti sement submitted and requires indemnity from adverti sers and contributors against damages whi ch arise from materi al published.

WATER June 1991 All materi al in Water is co~right and should not be reproduced wholly or in part without the wri tten permission of the ed itor.

A WHIFF OF HISTORY Compiled by W. J. Dulfer and E. A. Swinton

THE RELIEF OF SMELLBOURNE THE FOUNDATIONS The first formal meeting of the Melbourne Metropolitan Board of Works was held on 18 March , 1891.

Edmund Fitzgibbon, Melbourne's Town Clerk from 1856, had for 2 5 years taken the lead in pushing for sewerage. He was appointed as the first Chairman of the Board, and had the grave responsibility for raising the necessary finance at a time when Australia was in the grip of a recession caused by the collapse of the Land Boom speculation. The comments which follow later on his trials and tribulations have been extracted from the fascinating book "Vital Connections", reviewed elsewhere in this issue.

Prior to the proclamation of the Act establishing the Board , the Covernment had commissioned a report and recommendations on sewerage schemes from an English consultant James Mansergh. After its receipt the first Engineer-in-Chief of the new Board, William Thwaites, proposed a number of modifications which were eventually adopted to form the basis for the sewerage and land disposal system which has served Melbourne well for nearly 100 years.

The following brief excerpts from their two reports will be of interest perhaps not so much on account of "so what has changed" but as a challenge for today 's engineers to forecast I 00 years into the future ... i.e. to the year 2090.

(This Editor, in reading the original reports, was struck by the refreshing use of plain English, with complete absence of jargon.

The only point which tended to confuse the modern reader was the liberal use of vulgar fractions rather than decimals.)

MANSERGH'S REPORT. 1st August 1890. ' 'To the ... Premier of Victoria Sir, In accordance with an arrangement entered into with your Government . .. I undertook to visit Melbourne .. . last year . . . "/ arrived with my son and assistant, Mr. Ernest L Mansergh , on the 18th October and was introduced to Mr. Alexander Black. the Surveyor General, who had .. . prepared . .. contoured plans for my use. Within a few hours of my arrival Professor Allen, Chairman of the Sanitary Commission ... proposed to supply me with plans of certain schemes for the drainage of the Metropolis, which had been laid before the Commission by Local Engineers .. . "/, however, explained to him that I preferred not to see anything .. . until I had mastered the general configuration ... and come to some more or less definite conclusions.

Population: "The total population last year was stated to be about 427 200. ...· I communicated with Mr. H. H. Hayter, the Government Statist. and judging that five and forty years was not too long a period for design ... I asked that he consider the ... class of house property . .. in each Munidpality and how it is likely to be occupied in the future. He ultimately prepared ... a table ... showing among other things, the number of persons per acre in each district . .. and forecast for 40-50 years hence.

(Ed. The forecast was 1.7 million by 1935. In fact perhaps because of the 1930s Depression , it reached just over I million. The postwar boom had yet to come).

Water Supply: "Mr. Davidson, the engineer in charge of water supply, ... told me ... that in 1889 3 5 million gallons had been supplied in a day to 95 000 tenements, i.e. 87 gallons per head. and . .. said . .. that with the new 30 inch main being laid he would be called on to deliver 40 million gallons a day. Allowing for I I-I 2 million gallons for street and garden watering ... this leaves 28-29 million gallons for domestic. trade and other purposes. I assume this would amount to 65-70 gallons per head per day, and that when water closets are substituted for the present earth closets and pails,

provision for 75 gallons per head. This is a very much larger allowance than in England, but after fully considering the circumstances, especially the almost universal and very free use of baths, I am of the opinion that it is not too high a figure to adopt.

Rainfall: "Soon after my arrival, Mr. William Thwaites, of the Public Works Department, gave me ... a number of tables he had prepared. with other most valuable information.

Geology: "Mr. A . H Howitt (Mines Department) and Mr. R. Murray the geological surveyor put the whole of their published plans at my disposal ... and undertook a number of trial borings.

"But for the hearty cooperation of the above-named gentlemen, I should have been unable to master ... the district . . . in the time at my disposal.

Present Sanitary Conditions: "/ quote freely from the admirable and exhaustive Reports of the "Royal Commission, . .. appointed in March 1888''. My Report may be considered in a sense a sequel . .. I only wish that I could employ stronger language . ..

Sewage and Surface Water: "The liquid . .. consists of water from the waterworks, and the rain which falls upon roads, roofs and other open spaces, the water supply having been fouled by use. At present both pass into the streams and rivers or into the Bay. In my opinion there is no alternative but to discharge all this fouled water into the sewers, ... it is suggested that bath water might still be allowed to go into the street channels, but this I cannot approve. ·: .. The existing surface channels may be retained for carrying off the rainwater . .. with some exceptions. A certain area around cab-ranks and places where cart horses sta nd should be drained through intercepting chambers to the sewers.

Really efficient surface scavenging . .. of the streets .. . must be resorted to to diminish the fouling of the rain water to a minimum .. . The Sanitary Commission say that "the first flushings in wet weather should be admitted to the sewers, but the rest should be excluded''. I am afraid that this would be difficult to carry out . . . I fear that mechanical arrangements would not be intelligent enough to discriminate . ..

Disposal of the Sewage: (After remarks on the use of cess-pits in England) ... ''Then the water closet was introduced . .. and where streams were small in relation to the volume of sewage ... trouble soon ensued . .. and devices without number were invented ... to remove the solids.

"Suffice it to say that after 30-40 year's experience we are left with three methods: I st. Discharge of untreated sewage ... to sea or large tidal river 2nd. Removal of suspended solids and part of dissolved impurities by . .. chemical precipitation. The clarified liquid to a watercourse, the precipitate, whether usefully or otherwise, upon land.

3rd. Over land for irrigation of growing crops and filtration through the subsoil.

"Around the British coast a number of towns discharge raw sewage to the sea with impunity . .. but as population increases . .. coast more closely studded with seaside resorts ... public is growing rapidly very critical ...

(After comparing the tidal flow of the Yarra with the Thames) .. ·: .. there is no part of the Yarra into which sewage can be passed with impunity. This being so is it possible to take it out to the Southern Ocean?

Ocean Outfall: "The map led me to the conclusion that it would be more costly than any alternative, since . .. the only practicable point was at WATER Jun e 1991

15

Cape Schanck. and the route would be a long tunnel through ...

Arthurs's Seat. ~ Port OutlaH: 'This would be only half the distance .. . but I requested a series of tidal float experiments . . . and conduded that under no conditions could it be used for raw sewage .. ~ must therefore fall back upon either land or chemical treatment and my predilection is certainly for the former.

Cltemk:al »-eatment: Mansergh then summarised the processes of both batch and continuous precipitation. using lime. aluminium sulfate. iron salts and charcoal. and sludge drying by centrifuge. steam drying or pressing (plate and frame filters).

Land n-eatment: 'The ... general configuration of the area ... led me . .. to seek suitable land to the south east and south west . . . I soon found that the Sanitary Commission had antidpated this and prior to my arrival had caused levels to be taken and trial borings in these two directions ... "/ have selected 2150 acres at 'IAkrribeeand 3000 acres between Mordialloc and Dandenong . . .

'There is little doubt that heavy crops can be produced under sewage irrigation ... experience will find the readiest market .. .

The sewage farms which have done best finandally are those .. . which tum the crops into beef and mi/Jc. There used to be a prejudice against sewage-grown vegetables. milk and beef . .. this has quite died out except in respect ofsuch things as watercress. and I have every sympathy with this objection. ··1 have never- heard of any harm accruing to man or beast and I have been intimately associated with sewage farming . .. since the first one I designed in Carlisle. in /Bf,() . . . " With 30 years experience . . . I have no hesitation in recommending . . . irrigating of the lands I have selected in \loerlbee and MordiaJloc. The area required is one acre per 110 persons at l\t'nibee and one acre per 80 persons at MordiaJ/oc.

I cannot help thinlcing that in a country and climate where rain is so highly prized. 6000 irrigated acres within a few miles of Melbourne . .. ought to become very valuable.

Mansergh then summarised the options . ..

Scheme A ... gravitation to Mordialloc and "\M!rribee Scheme B ... pumping into two gravity outfalls Scheme C ... ooDection of all sewage at Williamstown. and a rising main to "\M!rribee Scheme D .. . chemical precipitation near Williamstown.

Scheme E ... a modification of 8.

Scheme F ... cape Schanck outfall.

Scheme G ... "\M!stem Port outfall. ... quanlifies 1Me.re fair.en out and detailed estimates . .. led to the final Scheme M . which was fully documented on 25 ithographed plans. This entailed two systems. one with a pumping station at South Yana. taking 60~ of the sewage to the Mordialloc Farm. The other coDec.ted the Bayside sewage. taking it under Hobsons Ba~ i<>ining the drainage from the western suburbs at a pumping station at Stoney Creek. from which it was to be pumped via three wrought iron rising mains of 63 inches diameter into an outfal sewer of 114 inches diameter. to the "\M!rri>ee Farm.

Mansergtas report concluded with an ~ t of the capital and operating costs of Scheme Mand the rates necessary t o ~ them. which were to reach a maximum of 7.52 d in the £ in 1898 •• :- notinddngthemstoflocalS1e11oeSafter 1898 because I ~ tlJe5le wodd be .. . atthecostofthe landowners opening out new buiHng estates'1t has been neces-sa,y to IMlf-t out tun particulars ix estimates ~ ... 50mil5onpounds . . . itwiBbeseet1thatnotime was lost . .. justice could not be done in Jess than six months . .. and I am c,atelul to the hard IMlf-k of my assistants . . :·

WW.I.AM TIIWIUTES' REPORr. 7th. July 1891.

As the Engineer of the Public \\bds Department. Thwaites had presented his views and designs to the Sanitary Commission in 1889. buttheCommis5ion had aheadyasRdthe~tfor a consuhant from ..Home.. to be brought in.

16 WA"IElt .lwte 1!191

Only a few weeks after his appoinbnent ~ the Engineer-in-Chief of the newly formed MMBw. he presented his Report. He praised Mansergh's work and his recommended Scheme M. but then took Scheme C. one of the rejected options. modified it and persuaded the Board to adopt it.

(Ed. One wonders how closely this final scheme resembled his original proposal of two years before) .

Some excerpts:

"In order that the Commissioners should thoroughly understand the proposals ofMr. Mansergh. M Inst.CE . . . I thought it advisable to very carefu/Jy explain to the Board the reasons for. and probable aitidsms against his suggestions.

'The various methods of sewage collection . . . are: /. The Pail System 2. Pneumatic System. like the Uenur and Berlier methods 3. The Water- Carriage System.

I ••• at its best it is an offensive method. and only deals with a portion of the polluted matters.

2 . .. one of the most complicated and costly processes for dealing with the solid ofhuman excreta . . . partially introduced at Leyden.

Amsterdam and Dordrecht . . . which towns are flat and intersected by canals . .. and it only deals with a portion of the causes of trouble .. . a costly toy.

3 .. . general roncensus so strongly in fa110Ur . .. that no alternative considered" Thwaithes reviewed all Mansergh's options. analysing the relative costs . . . and finishing with . . .

"Scheme C which is designed to carry all the sewage to \\erribee. a method highly thought of by Mr. Mansergh. is estimated . .. as considerably more than Scheme M . . . but by making the modifications recommended elsewhere. the cost can be reduced to Jess than Scheme M without altering the efficiency·: He discussed the problems involved in installing large sewers ahead of demand.

"Thesewersaredesignepfortheprospectivepopulationof 1939. but for years the amount they have to deal with will be small . .. and trouble may be anticipated unless flushing is freely resorted to ... (to achieve a -velocity of l50feetperminute)'' ... With these large 5elMel'S it.would take all the water at present available to keep them in condition during the heat of summer. .., am of the opinion that . . . we should reduce the capacity . . . to agree with the data given by Mr. Mansergh . . . but to run at ¾ full instead of ½ full''.

He discussed in detail the costs of the pumping stations and concluded ...

'There is not the slightest doubt that concentrating all the

machinery in one station ... would be much cheaper''.

With better knowledge of local politics. Thwaites foresaw the development of Melbourne to the east.

"The original cost of purchase of the farms has not been taken into consideration. and \\etribee will cost very much less than MordiaJloc. The eastern farm is in the middle of a more thickly settled district. and there/ore the opposition is sure to be very strong. from sentimental reasons. if not from more substantial ones . . . The effluent channel enters the sea opposite the township. which is sure to be objected to .. :: He then refened back to his original proposal: ..When dealing with this subject. in 1889 I gave my reasons for preferring l\t'nibee to Mordialloc ..: (Ed: which can be sqmmarised as: Most economical: rainfall lowest greater area below the contour: effluent to Bay without nuisance: no population in vicinity: a large area for extension: soil is suitable. though not as valuable as Mordialloc: the Geelong Railway would assist marketing). and he concluded with: ..Having now dealt. as fully as time would permit. with the leading prindples involved in Mr. Mansergh's

report I have the honour to condude with. ...

And he won.

IMPLEMENTATION When the new Board was formed it had a charter to build a sewerage system. to take over the water Supply Department and

its staff. and to operate both systems. It was assumed that the Board would borrow to finance the sewers. while revenue from the water rate would cover operating expenses and interest payments.

In September 1891 it was decided to raise a £2 000 000 sterling loan in London. the source of much of the finance for the capital works of water supply. railways. ports and harbours and municipalities in the colony. However. by the end of the year the flow of funds from London had begun to slow down and there were growing signs that the Victorian economy was sliding into crisis.

In early 1892. Fitzgibbon raised £500 000 as a short-term loan on the local market. which . together with the debentures used to purchase the Werribee land from the Chirnside family. enabled work to commence. He then sailed to London to try in person to raise the £2 000 000. and was received rather superciliously. finally succeeding in raising only £1 000 000 on less favourable terms than had been planned. Also. the British Government and the financiers together milked £10 000 out of the total. Returning to Melbourne. Fitzgibbon lodged the remainder equally between three major banks. Unfortunately. in April 1893. in the depths of the depression then being experienced in Australia and in Melbourne in particular. the run on cash forced one of the banks to close its doors. and within a month the other two followed suit. thus freezing the hard-won funds. However. one bank was good enough to advance £80 000 ... at overdraft rates . .. Meanwhile work was proceeding. but with the limited funds available. letting of crucial contracts had to be deferred, and staff cuts and salary reductions imposed. Naturally there was strong agitation to drop the scheme or to limit it to the city and inner suburbs. but the Board held its ground. The financial pressure was not eased until September when Fitzgibbon went to the citizens themselves and raised £500 000. (Ed: there must have been a lot of sovereigns hidden under mattresses that year) .

One can only admire the foresight and courage of Fitzgibbon and Thwaites in proceeding in face of so much adversity. At one stage Thwaites ordered work to proceed on the site of the Spotswood pumping station even whilst an appeal was being heard at the Land Valuation Board to reduce the inordinate price being asked for the parcel of land. (Presumably the owners hoped that it would be valued as prime Bayside suburban development).

Many sleepless nights must have been experienced. but they both saw that Melbourne's future depended wholly on the construction of the sewerage scheme. which was to serve the city for the next fifty years with no significant augmentation.

In the event. despite these difficulties. the first connection to the system (to an hotel!) was made in August 1897. a litle over six years since the first meeting of the Board. In the first two years. by late 1893. the first areas of the farm had been graded and prepared . the outfall from Brooklyn to Werribee excavated and lined. and the rising main from Spotiswoode to Brooklyn put in place. Deep sewer tunnels were being driven in difficult conditions, the ground to be excavated (by manual labour) varying from solid basalt to running sands and silts. These necessitated the use of the modern

Pipe Storage

technology of the compressed air caisson, in which Melbourne became a world leader.

Work on the pumping station started in March 1894 . and the first steam pumps were trialled in February 1897. By 1900. nearly 60 km of main and branch sewers and 440 km of reticulation sewers had been installed, with most of the pipes being manufactured in Australia.

It was a truly herculean achievement: the speed was impressive and would be hard to match today.

It is probably true to say that this immense investment in valuable infrastructure "kick-started" the Victorian economy, which was experiencing a 2 5 % unemployment rate.

It is of interest that the Victorian Government decided at the outset to employ only the best men at the top, and advertised both the Chairman's and the Engineer's appointments at £2000. The engineer's advertisement ran for only one month in order to restrict the field to Australians. Thwaites won convincingly, at age 37, from a total of 43 applicants. (one of whom was the young John Monash). Later, during the financial troubles. Thwaites salary. as with other public servants, was cut to £1500, but Fitzgibbon held firm . Both men died in office. Fitzgibbon at 79 . Thwaites at 53.

• Mansergh's consultancy was worth £4000 plus expenses. which covered three months of travelling, two months in Melbourne and six months in the London office. for the two Manserghs and their draftsmen.

1 (To try to put all these figures in perspective. in 1890 the Professor of Engineering at Melbourne University earned £1000. Thwaites' salary as Chief Engineer at the Public Works was £700. and he tripled it overnight. The Retail Price Index indicates that the value of money has degraded by a factor of about 40 since the turn of the century. Using this factor to convert to 1991 dollars puts Mansergh's total estimates for the scheme as around $4000 million. the salaries as $160 000 p.a .. and the consultancy at $320 000.

It is also of interest that at the turn of the century the average wage for a working man was around 40 shillings a week. or 4 "dollars". For this level of income the factor is not 40, but over 100. whereas a professor's salary has only increased by a factor of 35) .

ONE HUNDRED YEARS LATER ... THE MELBOURNE WATER CORPORATION In this Centenary Year of The Board of Works. it is not only celebrating 100 years of service to the people of Melbourne, but also marking the end of an era.

On the January 1st. 1992. the Board will be corporatised. and will be known as the Melbourne Water Corporation. This is not just another name change.

Prior to that date. it will be merged with a number of smaller water authorities to the south east of the city, to form a larger organisation aimed at rationalising the business of water supply. wastewater treatment and disposal. the drainage and watercourses of the area and the management of open spaces.

It is expected to eliminate the inconsistent and sometimes uncoordinated approaches due to the boundaries of the existing authorities.

Just on I 00 years ago. the water and sewerage responsibilities of the six Cities. six Towns. six Boroughs and six Shires which at that time constituted the Greater Melbourne area . of 134 square miles. were merged in the same way to form the MMBW. A nice quirk of history.

The more significant issue of the effects of corporatisation on management have been and will continue to be discussed at length in various venues around the nation. Different structures are emerging in each State. but the general thrust is for a more commercial approach and increased customer service. Whether the retention of the assets by the Governments of the day will allow operation free from political interference. apart from the necessary regulations. rema ins to be seen.

Roll on the next hundred years.

WATER June 1991

17

1891 - MELBOURNE METROPOLITAN BOARD OF WORKS --THE FOUNDING FATHERS - -

Edmund Fitzgibbon The Visionary

James Mansergh The Consultant

William Thwaites The Engineer

"Publica Salus Mea Merces" Public Health is My Reward

BUILDING THE TRUNK SEWERS Tunnelling through running sands and silts demanded new technology. The Clarke Shield , kept dry by compressed air.

The Board operated one of the first decompression chambers to overcome 'the bends'

The Hobsons Bay Main below the Yarra took three years to drive and killed seven men. It was still in use in 1969, when it had to be lowered to deepen the river.

Laying of the first brick, lining the Outfall Sewer.

Wrought Iron Pipes for the Rising Main in the Contractor 's Yard.

Spottiswoode Pumping Station: No.4 Engine ir the Northern Room.

1991 -- THE BOARD OF WORKS

DIGGING THE WESTERN OUTFALL

Part of the new western trunk sewer.under construction .

THE MODERN MANNER: THE MOLE (Designed in Melbourne, built in USA, guided by a laser beam)

BOARD OF

WORKS ,-,

9.5 km of 3. 35 m diam . of open channel.

Some brick-lined. some concrete.

All completed in 18 months.

The Thomson Dam offtake tower, under construction in 1982

An 1890 diversion weir supplying the aqueduct to Preston

FLOOD CONTROL

Queens Bridge awash in 1891 and Right- · Peace on the Yarra (The 1/1000 year flood still to come) With ac kn owledge ments to the Corporate Com mun icat ions Unit of the Board of Wo rks

THE YARRA RIVER CONFERENCE. 13-16 April A report by Bob Swinton

INTEGRATED CATCHMENT MANAGEMENT A major event in the Centenary celebrations of the Board of Works was a conference with a difference, which attracted over 200 registrants.

The theme was the Yarra River, for which the Board has responsibility, and its aim was to focus on the future development of the river from its source in the catchments to its relationship to the city and its people. The overall theme was to describe the river as it has been and as it is now, and so to determine what we would like it to be in the next century, because whatever we do now must aim in that direction.

The Board invited a number of leading experts to present a huge range of papers examining the river's heritage, history, environment, recreational uses, natural resources, development, commercial significance and its effect on land use. This was a far broader canvas ¡ than the normal interests of the AWWA, since the conference was aimed at the concerned citizens rather than the professionals. It was, in effect, an exercise in Integrated Catchment Management, but accentuated since the river in question ran through the centre of the capital city!

NATURAL AND HUMAN HISTORY A paper on the flora and fauna noted that the upper regions had large areas of pristine forest, due to the protected water catchments, the middle zone still had some ecosytems left which deserved protection, but the lower regions were so extensively modified by settlement that it was impossible to return them to any semblance of their initial form. The paper on geology and run-off characteristics noted that the river was unusual in that its flood plains were in its middle zone, due to the Warrandyte gorges and the basalt shelf, and that without this characteristic, the city would be far more vulnerable to flooding.

The presentation on the heritage of Aboriginal culture was poignant, and finished with the hope that 'The Awakening Time' could result in working together to repair the damage.

The history of European settlement was presented by a succession of speakers, each versed in a particular aspect, and orchestrated

by Dr. Tony Dingle, the author of the book, "Vital Connections".

It was conveniently punctuated into the periods between the great floods.

1803-1863. Ignorance and neglect. Despite warnings by the aborigines and some minor floods, the flood of 1863 stuns the settlers.

1864-1891. Abuse by the rapidly growing city. The river used as the sewer for both domestic and industrial wastes. The forests exploited, the port developed below the bridges. Finally, the Board of Works commissioned to sewer the city.

1891- 1934. Gradual appreciation by the people. The Heidelberg School of artists catch the peace of the middle reaches, bushwalkers explore the forests of tall trees, hundreds of small boats and canoes fill the lower reaches and Henley-on-Yarra attracts half the population every year for its autumn festival. The river is part of the people. Flood control work commences, and there is a proposal to form a huge lake in the flood plains of Kew/ Ivanhoe. The Depression halts the timber industry in Warburton and when the 1934 flood comes down the unused logs are swept downstream as battering rams.

1934-1970. Neglect once again, as Australia focusses on war and industrial development. Postwar immigration and the baby boom means that roofs are far more urgent then sewers, and the river becomes so polluted that its recreational use ends.

1970- the start of the "Save the Yarra" campaign in the Press, and the start of the EPA. Gradually the attitudes change, environmental damage is controlled, and the Board develops huge river valley parks in the flood zones.

Throughout all this the Port of Melbourne had developed below the bridges, the big docks and the Coode Canal were excavated by manual labour. Later the Westgate Bridge was built high to allow

20

WATER Jun e 1991

the big ships to come through. But now, as containerisation has developed, the old Port is obsolete and the activity is shifting further out to the mouth.

INSPECTIONS The second day of the Conference involved a coach trip from the upper regions down to the start of the suburbs, with inspections and addresses on forest management, water supply flood plain management and use of open space for parks and recreation.

This theme was continued on the third day by an inspection of the industrial areas backing onto the river, which are gradually becoming gentrified, and a tourist launch trip through the city, out through the Port to the mouth of the river, with a commentary.

DISCUSSION In the Theatrette more papers addressed recent trends and initiatives, in urban redevelopment, recreation, the development of the Port and the options for use of the old port area. One paper outlined the scores of government, semi-government bodies and edicts, and the lobby groups which all have a say in the future of the river and its surrounds, with the implication of a recipe for chaos. However, since 1970 the Board has steadily built up a strategy and concepts for the lower and middle Yarra, which by means of Working Groups has managed to achieve a consensus between the various vested interests.

The results of such planning and development on the urban reaches have been dramatic, with the northern and southern banks in the City becoming a delightful pedestrian precinct, against a dramatic backdrop.

In a less obvious way, the water quality of the river has also improved dramatically, from . 3500 E. Coli/ 100 ml in 1970, to 500- 900 in 1990.

However, the integration of the river into the recreational pattern of the city dwellers will never recov<;r to the hey-days of the '30s.

The motor car and the beaches have taken over.

In the middle reaches, the policies of the Board have borne fruit.

Their parks are vital components of the Government's "Open Space 2000" program, and the Board's Advisory Council tries to coordinate the range of government bodies concerned.

Upstream, despite planning battles and restricted funding, the Upper Yarra and Dandenong Ranges Authority is maintaining a 'no-growth' area, but is losing the battle on a number of issues such as sewerage programs.

The long-term solution of the prospective release of the old Dockland to urban development is fraught with the perils due to the present economic plight of the nation, exacerbated in Victoria.

Despite the successes, in the general Forum the almost universal gripe was that there are so many bodies involved that it is almost impossible to achieve anything in Melbourne. (Some quotes .. .

"Melbourne talks, Sydney does" "Bureaucracy doth impede itself') One point made was that the Murray Darling Commission was an example of a successful agency which seemed to be coordinating the differing agenda of four States, as well as the local lobbies. In answer, it was said that they had a relatively simple clearly-identified agenda, the dominance of salinity being at the forefront. With Integrated Catchment Managment on a smaller scale, as with the Yarra Valley, the self-interest of parties at the second level of significance generates lots of debate, but little in the way of results.

To achieve results ... take heed of the lessons learned in nonmetropolitan river catchments . . . get a clear idea of objectives.

Choose a couple at a time, which are measurable and accountable, then apply funding to tackle them effectively.

The proceedings are a mine of information and inspiration. A bound summary of the papers will be available later this year for the nominal price of $10. Copies of the audiovisual record of this Historical Presentation are available for $20. Apply - Manager Watercourse Environment, Board of Works. Fax (03) 615 5422.

The Werribee Treatment Complex __, An Environmental Perspective

By A.J. BREMNER and A.W. CHIFFINGS SUMMARY The Werribee Treatment Complex (Werribee "Farm") has been treating Melbourne's sewage using land based treatment systems for 93 years. Now totalling an area of 10 850 hectares, the Complex uses three treatment systems, land filtration, grass filtration, and lagoons, with the final effluent being discharged into Port Phillip Bay. To date, scientific studies have not demonstrated that the effluent, which is discharged in accordance with EPA licence conditions, has caused any adverse effects on the Bay. The Complex itself supports an abundance of wildlife and is managed in accordance with a specially prepared Wildlife Management Plan. The Complex is recognised as a "Wetland of International Significance" and is also the subject of several International Treaties relating to the conservation of migratory waders and other species.

Development strategies presently being prepared for the next 50 years for the Complex will not only consider sewage and other waste treatment needs for the city of Melbourne, but environmental and wildlife management needs of the Bay and the Complex itself.

INTRODUCTION "I have no hesitation in recommending that the best way to deal with Melbourne's sewage is by irrigating the lands that I have selected at Werribee and Mordialloc."

James Mansergh's Report. 1890.

The foresight represented by this statement can well be appreciated 100 years later. The sewage treatment facility at Werribee has served Melbourne's needs admirably for this period and is anticipated to continue to do so far into the future. In fact the current strategy for the development of the Werribee Treatment Complex has a planning horizon of 50 years.

The Board commenced operations in 1891, in response to the then obvious need to protect the community of Melbourne's health by taking responsibility for the collection, treatment and disposal of its wastewater. It established a network of underground sewers to collect wastewater and transport it to the Werribee Treatment Complex, known affectionately as "The Farm", for treatment. The original sewerage system was designed by Mansergh to convey and treat wastewater from a population of 1.7 million people (Chiffings et al , 1991).

The quantity and quality of wastewater handled by the sewerage system has changed over the intervening 100 years with both the volume and pollutant load increasing substantially. This increase has resulted from: •increasing population and establishment of households (pop. of 477 790 with 33 972 (32%) properties connected in 1897 c.f. pop. of 2 585 000 and 982 000 (98%) properties connected in 1990); •changing living standards which have lead to an increase in the per capita wastewater production; •increased industrial development. The Board has Trade Waste Agreements since 1949, with some 5000 customers ranging from laundromats to major chemical industries at present; •the sequential enlargement of the area for which the Board is responsible (Fig. 2).

The Board's sewerage system has been progressively expanded to cope with the increased demands placed on it by the community of Melbourne. In 1975, the Board divided the sewerage system into two major systems. The Western System based on the Werribee Treatment Complex discharging to Port Phillip Bay, and the Eastern System, based on the South Eastern Purification Plant at Carrum which discharges to Bass Strait at Boags Rocks via the South Eastern Outfall.

The Eastern System was established because Werribee was approaching its capacity and the majority of Melbourne's growth was in the east and south-east.

Dr. Allan Bremner, Manager, Toxicants Program Melbourne Board of Works.

Allan has been the Manager of the Board's Toxicant Program since May 1990. In this role he has been responsible for dealing with issues such as the Greenpeace/ Nu/arm incident of last year. Previously he was Manager, Environmental Services. He has held positions as an environmental manager, research manager and organisaA. Bremner tional manager. He has extensive experience in toxicants and has serverd on a number of international groups of experts for UN agencies.

Dr Tony Chiffings is presently the Coordinator for Environmental Studies in the Melbourne Board of Works, where he is developing and managing environmental studies relating to the impacts of the city of Melbourne on coastal and marine environments. His resource management interests centre around methods and techniques for achieving sustainable development in marine and coastal environments.

T. Chifflings

6700 hectares are used for treatment purposes with the balance comprising plantations, roads, channel reserves and livestock dry grazing areas. (Fig. 1) The land is relatively flat with an average gradient of 1:1000 which lends itself to a regular layout pattern for irrigation and drainage of treated effluent to the foreshore of Port Phillip Bay (Croxford 1989, McPherson 1989). It began operation in 1897 following the acquisition of 3580 hectares in 1893. The area, identified by Mansergh, met the b<\5ic requirements for a land treatment system, namely suitable soils, high evaporation and low rainfall. Initially 515 hectares were used for land filtration and the balance leased for dairy farming and vegetable growing. In 1900 the Board ceased leasing land for these other purposes and used it for additional wastewater irrigation in winter and sheep grazing in summer. Cattle were introduced in 1910 and since then the Board has continued to graze both cattle and sheep.

Successive land acquisition has seen Werribee Treatment Complex expand to its current size. The grass filtration treatment process was introduced in 1930 to treat winter flows, followed by the introduction of lagoons in 1937 to treat daily peak flows and wet weather flows which exceeded the capacity of the land or grass filtration processes.

Treatment areas 1. Permanent pastures 2. Grass filtration area 3. Lagoon area 4. Sludge digestion area 5. Supernatant liquor lagoons 6. Unirrigated pastures

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THE WERRIBEE TREATMENT COMPLEX The area of the Werribee Treatment Complex is 10 850 hectares through which the Little River and some minor streams drain. Some 22

WATER Jun e 1991

l'rirt l'hil/1p Roy

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Murtc11.1m 1111\.in tlr11\n outlet

The Werribee Treatment Complex has served Melbourne's requirements for economic treatment of its wastewater to a high quality effluent since its inception in 1897, estimated as being 9.6 million ML over the full period. Throughout this 93 year period the final effluent,has been discharged to the Bay. The Complex still treats some 55% of Melbourne's sewage (500 ML per year) to a currently acceptable quality for discharge to the Bay under licence from the Environment Protection Authority.

TREATMENT PROCESSES There are three treatment processes at Werribee - namely land filtration, grass filtration and lagooning. In general the more permeable soils adjacent to the Werribee River are used for land filtration (3400 hectares), the heavier clays and loams on the western side of the Complex for grass filtration (1500 hectares) and the lower foreshore areas for lagooning (1650 hectares).

Land Filtration Land Filtration involves irrigation of permanent pasture bays with mainly raw sewage during the months of high evaporation, (from October to April) . Each bay is given approximately 1 to 2 days irrigation followed by 5 days drying and a 14 day livestock grazing period - an operating cycle of 21 days. The irrigant is 'purified by filtration through the soil, while the contaminants and nutrients remain in the soil. About 40% of the volume is collected by sub-surface drains and discharged to the Bay. The remainder is lost through evapotranspiration.

Grass Filtration Grass filtration involves continuously passing sedimented sewage through Italian Rye grass on graded areas at a slow rate. The suspended matter is filtered out by vegetation and the organic matter is removed by a biologically active film built up on the plant stems.

The effluent from this is collected by a network of drains and discharged to the Bay. This process is used during the months from May to September, when evaporation is insufficient to allow land filtration to be used. At the end of this period the grass filtration areas are allowed to dry out, the grass goes to seed and cattle are admitted to graze on the dry vegetation. The grass remaining on the ground is germinated by rain or irrigation in the following autumn to provide for the following operational season.

Lagoon Treatment Until recently each lagoon consisted of a series of 8 to 12 ponds with oxygen being supplied by the natural processes of wind reaeration and algal activity. A lagoon development program has led to the use of a deeper high rate anaerobic pond, surface aeration on the second pond and the optimising of later ponds for nitrogen removal through nitrification/ denitrification. It is proposed to cover these anaerobic ponds, burn the gas, recover heat and possibly generate power.

EFFLUENT DISPOSAL High quality treated effluent, equal to secondary treated effluent from a "conventional" plant, is discharged from the Werribee Treatment Complex to Port Phillip Bay via five outlets. These discharges meet the requirements of EPA licences and are continuously monitored for effluent quality. The EPA licence conditions require the measurement of physical and chemical parameters in the effluent. In addition, the Board has carried out studies to assess the impact of these discharges on the biological communities adjacent to Werribee in Port Phillip Bay.

The sale of cattle is subject to the provisions of the Health Act 1979 and the AbattQirs and Meat Inspec?'ion Act 1973, and this

applies to cattle from the WTC. The slaughter and disposal of sheep is not subject to these same restrictions.

WILDLIFE Parts of the Werribee Treatment Complex were declared a sanctuary for the protection of bird life, including wildfowl such as ducks and quail, in 1921. It has long been recognised as an area of high conservation value and in 1989 this was formalised by the Board with the development and publication of the Werribee Wildlife Management Plan for the protection of its wildlife. The large area of the Complex encompasses a diverse and complex array of land forms, vegetation communities and wildlife. Although the development of the area as a sewage treatment facility has displaced or severely modified much of the original flora and fauna, it has prevented some areas from suffering the fullimpact of development while the presence of treated water derived from sewage has enhanced many aspects of conservation interest. These conservation interests can be categorised as follows: Avifauna Two hundred and fifty four species of birds are recorqed for the area which indicates its importance to avifauna conservation.

However the abundance of some species, the occurrence of rare and endangered species and the high proportion of the total world, national and state populations of other species that utilise the area make the Werribee Treatment Complex one of the foremost conservation areas in the world. Migratory waders fly to Werribee during the northern winter from northern China and the USSR. It has been given International Significance Status for avifauna in four categories, National Significance for two, State Significance for six and Regional Significance for four.

Mammals, Reptiles and Amphibians Werribee also provides a sanctuary for many other animals of importance. Amongst these are the Fat Tailed Dunnert and a legless lizard, both of which have state conservation significance. Two frogs, the Green and Golden Bullfrogs and the Spotted Burrowing Frog, the Metallic Skink, White Lipped Snake, native Water Rat and the Platypus are species of Regional Significance.

Flora -, The Werribee Treatment Complex area has a diverse array of vegetation communities and species. These form an essential relationship with the land form, land types and wildlife. Seven species of plants are classified as Restricted or Rare. Of these rarer plants one, the Little Dumpy Orchid was listed at only five locations in Victoria, with its survival being doubtful in some of these.

The abundant wildlife and habitat of Werribee is a natural resource of considerable importance, not only to the rate-payers of Melbourne but to the state and national communities. The declaration of the Werribee Treatment Complex as a "Wetland of International Importance" by the International Union for the Conservation of Nature (IUCN) in 1983 highlighted the need for a co-ordinated approach to the protection, conservation and enhancement of its natural and artificial attributes. The significance of the area's contribution to conservation is further illustrated by International Agreements with Japan and China on the protection of migratory waders and by State and Local Agreements on the protection of wetlands and other habitat.

LIVESTOCK

SUSTAINABLE DEVEWPMENT

Apart from its primary function of sewage treatment, the Werribee 'freatment Complex is a combined beef cattle and sheep station comparable to some of the largest in Australia in terms of numbers of stock. Livestock grazing forms an integral part of the land filtration and grass filtration processes. In most years, it yields substantial financial return which significantly reduces the net cost of sewage treatment.

The basic herd of 12 000 cattle produce about 4500 calves each winter, which are held as replacement breeders or fattened as steers and sold at 18-22 months of age.

Sheep are not bred at Werribee but are bought in the spring and fattened and sold in the autumn. Normally 20 000 to 25 000 sheep are carried during the summer, although there have been as many as 72 000. Flocks of 6000 are retained during winter for essential grazing purposes.

Sustainable Development requires that operations must be economically viable, socially acceptable and ecologically sustainable (Bremner et al 1989). The Werribee Treatment Complex is perhaps the oldest and best example of the implementation of these principles in this country. It treats more than half of Melbourne's sewage, including industrial waste, in an economic fashion; supports a large sheep and cattle operation; is a wildlife habitat of international significance; and acts as the "last line of defence for Port Phillip Bay" against the impact of Melbourne's sewage. It is a significant facility in the Board's responsibilities to fit Melbourne into the environment.

THE FUTURE -

THE DEVEWPMENT STRATEGY

The Board is revising both short and long term strategies for the sustainable development of Werribee to ensure that it continues to WATER June 1991

23

meet its requirements for the treatment of Melbourne's sewage in future years. These strategies are being developed to meet a number of issues which are outlined below. It is important to note that these strategies involve full consultation with a Community Advisory Committee which includes representatives of the local communities surrounding the complex together with representatives of the Werribee and Corio Councils. The major issues are: Sewage Flows in the Western Catchment An overall increase in dry weather flow in the order of 55% is expected in the next 45-50 years, from 470 ML/d in 1988 to 730 ML/ din 2035. These flow predictions were made on the basis of proposed catchment boundaries, town planning zoning, projected population growth, residential flows , trade waste flows and infiltration flows.

Odours The impact of odours on the public is a major environmental issue for the future development of Werribee. The existing treatment processes generate odours of varying intensity and frequency which can be detected outside the boundaries of the Complex. The Board is committed to progressive and significant improvement in odour reduction.

Effluent Quality Port Phillip Bay is arguably the major recreational area of the State of Victoria. It is also of significance for tourism, conservation and commercial marine enterprises such as fishing, mariculture and shipping (Bremner et al, 1989). The quantity and quality of the Werribee effluent can potentially impact on this resource and the Board is continually investigating this in collaboration with other relevant Government authorities. The parameters of interest in assessing the impact of the WTC effluents are nitrogen, suspended solids, biochemical oxygen demand, colour, heavy metals and other toxicants. The Board has a current program to investigate these impacts and ways to overcome those that are unacceptable.

Complementary to past activities, the Minister for Conservation and Environment, Mr Steve Crabb, announced in June 1991 a major 3 to 5 year Study of the Bay which is to start immediately and is directed towards setting the management framework for the the whole of the Port Phillip Catchment for the next 20 years. The study is to concentrate on the impacts of nutrients, toxicants and the physical processes of the Bay. As the WTC contributes an estimated 50 per cent of the nutrients to the Bay, and consistent with the Board's role as environmental operations manager for Melbourne in the areas of water regulation (supply and drainage) and waste management, the Study will be funded by the Board, and managed in collaboration with the EPA, Port of Melborne Authority and the Department of Conservation and Environment.

Conservation and Wildlife As discussed above the Werribee Treatment Complex is a wildlife refuge of international significance. Hence any alteration to the current treatment methods will be assessed in the light of its effects on wildlife. The Werribee Wildlife Management Plan aims to achieve this.

Chemical Residues · There are numerous chemicals used in our society both domestically and industrially. Some of these are of concern because of their toxicity, carcinogenic properties, persistence in the food chain due to resistance to biodegradability and so forth. These materials enter the sewerage system by illegal dumping, inadvertent industrial discharge, trade waste discharges and domestic sewage.

The issues associated with toxicants are receiving urgent attention with a toxicant assessment program in place since December 1989.

This program was developed on the basis of data collected in earlier investigations and monitoring programs on toxicants in the sewerage system. The program aims to assess the levels of toxicants in areas of the environment receiving treated effluent from Board treatment plants and the impact of these on human and environmental health (if any). If these are found to be unacceptable, investigations will be undertaken in the sewerage system to eliminate the sources. Work to date indicates that both domestic and industrial sources will need to be considered. The Waste Minimisation Policy will further encourage the reduction of waste discharge, including toxicants to the sewer.

As part of this program the Board commissioned an independent review of its Trade Waste practices by a review panel, chaired by 24

WATER June 1991

Emeritus Professor John Swan. The review extended over three months and reported to the Board in Octbber 1990, following a three week period for public review and comment on the interim report. The review covered the effectiveness of the Board's Trade Waste operations, the Trade Waste Agreements, the framework used for the assessment and monitoring by the Board to ensure that human and environmental health requirements were met and a review of the organisation and management of Trade Waste activities and accountability to the community. The review report contains a number of recommendations which are currently under consideration and others which have already been implemented.

Greenhouse Effect The Greenhouse Effect is the phenomenon of global climatic change wrought by the warming effects of increased atmospheric levels of carbon dioxide, methane and other "greenhouse" gases.

Current predictions are that a doubling oi atmospheric carbon dioxide (or its equivalent for greenhouse gases in general) will raise the earth's mean surface temperature by l.5 - 4.5 °C. within about 50 years. This is expected to result in major changes in regional climate and in sea level rises of between 0.2 and 1.4 metres through thermal expansion. This possible rise in sea level is of direct relevance to the management of the WTC through its impacts on the stability of the adjacent coastline, and on the lagoons themselves through changes in final drainage heights effecting the flow of effluent into the Bay. Consideration of Greenhouse effect predictions are essential as the time for occurrence is within the life-span of any newly created wastewater treatment assets. New wildlife habitat may need to be created to protect such species as the Orange Bellied Parrot and migratory waders. This may occur naturally provided adequate buffer zones are made available in these new developments.

Capital and Operating Costs The Board of Works as a semi-government instrumentality must act within the policies and direction of the State Government in certain financial matters. In simple terms the demands in regard to finance within the Board are expected to be: • Recurrent expenditure should be such that the rise in rate revenue is less than the rise in the Consumer Prke Index.

• Rate of Capital Expenditure should not increase in real terms.

• An appropriate Public Authority dividend should be paid to the State Government.

It is recognised that significant capftal expenditure will be required as will increased operating costs, to address technical and other issues facing the Werribee Treatment Complex. These increases must be maintained at the minimum level consistent with community standards and expectations in other areas of Board of Works and Government involvement.

CONCLUSIONS The Board of Works Werribee Treatment Complex has played a significant role in fitting Melbourne into the environment for the last 100 years. It has done this in a manner which is in general socially acceptable, economically viable and ecologically sustainable, thus meeting the requirements of the principles of sustainable development. It has not only provided a high level of treatment for Melbourne's sewage but has also generated income from its large stock operations and supplied a wildlife habitat of International Conservation Significance.

The Development Strategy for the facility has been designed to meet the challenges of the future to ensure that it continues to meet these increasing demands whilst maintaining its excellent past record of performing for Melbourne's needs. The Board believes that it can continue to operate this facility in a manner that treats waste water from the Melbourne community to an environmentally acceptable quality.

REFERENCES I. BREMNER, A.J., WOOD, K.L. and CHIFFJNGS, A.W. (1990) "M elbourne and the Coastal Environment: A Review of the Impact of Melbourne on Victoria's Coastal Environments" 2. CHIFFINGS A. W., BREMNER A. J., BROWN V. B. (1991) "The Management of Nutrient Loads to Port Phillip Bay" submitted to Proc. Royal Soc. Vic. 3. CROXFORD, A. H., 1978. Melbourne, Australia, wastewater system - case study.

Presented at the 1987 Winter Meeting, American Society of Agriculural Engineers, Chicago, USA 4. McPHERSON, J.B., 1979. Land Treatment of waste water at Werribee past, present and future. Prog Wat. Tech. , 11

WATER DEMAND MANAGEMENT . IN MELBOURNE

by H. P. DUNCAN SUMMARY The broad objective of a water supply authority is to match supply and demand, with a level of service acceptable to the community.

Water demand management has now been used successfully in many Australian towns and cities, and is increasingly recognised as an effective and acceptable alternative to supply augmentation.

In Melbourne, the Board of Works introduced a demand management campaign in 1983, at the end of a year of water restrictions. Intiially this was based on advertising, education, and appliance redesign. In 1987, a pay-for-use charging system for water was introduced.

A sustained reduction of 16% of pre-drought annual ¡consumption has been achieved. Winter use has averaged 6% below the expected level. Summer use has averaged 26% below the expected level, and peak day consumption shows a similar reduction.

The resulting deferral of head works and distribution works has a present value of up to $75M. The demand management campaign has been highly cost effective. The cheapest water available in the future may well be the water which was wasted in the past.

INTRODUCTION The broad objective of a water supply authority is to match supply and demand, with a level of service acceptable to the community.

Water demand management is increasingly recognised as an effective and acceptable alternative to supply augmentation.

In Perth, the Metropolitan Water Authority introduced a payfor-use charging system for water in 1978, during an extended period of water restrictions. Restrictions were lifted in 1979, but total water use in 1981/82 was still well below the level experienced in 1975/76, despite an increase in the number of services. There was an increase in the number of private bores used for watering gardens, but after allowing for increased bore ownership, and trends in household size and income, household water use decreased by between 100 and 160 kilolitres per year. This was 20 to 30% of pre-drought use (Clarkson, 1985).

In Newcastle, the Hunter District Water Board introduced a payfor-use charging system for water and sewerage in 1982, again after ¡ a period of heavy water restrictions. For charging purposes, sewage flow was assumed to be 50% of household water consumption.

Ther_e was a substantial and immediate decrease in consumption, and m the long term a reduction of at least 20% of pre-drought use has been assumed. Headworks augmentation has been deferred by at least ten years, giving a saving of $15M in net present value (Broad, 1985).

In Melbourne, the Melbourne and Metropolitan Board of Works introduced a demand management campaign 'in 1983, at the end of a year of water restrictions. Initially this was based on advertising, education, and appliance redesign (Heeps, 1986). In 1987 a payfor-use charging system for water was introduced. A sustained reduction of 16% of pre-drought consumption has been achieved (Duncan, 1991). Annual water consumption in Melbourne is shown in Figure 1.

All these examples involve a reduction in demand, although the term 'demand management' is itself neutral, and could imply either increase or decrease in demand . This simply reflects the fact that supply to meet unconstrained demand has rarely been questioned in the past. Now, with high regulation of resources and rapidly rising costs for new works, better utilisation of existing sources is an increasingly attractive alternative. A moderate reduction in demand will often be a cost effective solution.

BACKGROUND Before the 1982/83 drought, Melbourne's water use was growing at nearly 3% per year. If this growth had been allowed to continue, the supply system would have needed doubling every 20 to 25 years.

The costs of developing such a system would increase even more rapidly, because the cheapest sources of supply close to Melbourne

Hugh Duncan graduated BEng(Hons) from Monash in 1973, specialising in water resources. He has also gained an MEngSc by part time study and has worked for the MMBW in Drainage, Forest Hydrology and now is in the Water Resources planning area.

H. Duncan

dist_ant sources, which may also be required by other users, and environmental costs of a rapidly expanding system would be very high.

In September 1983, a task force on demand management was formed as part of the State Water Plan. The task force had responsibility for implementing measures to reduce the trend towards greater use of water by each household in Victoria. The overall objective of the task force was to encourage more efficient use of water, and thereby reduce the long term growth rate in water con~umption (Bugeja, 1985). To prevent increased efficiency being achieved at greater cost, the net cost of any measures to improve efficiency should be less than the cost of harvesting additional water.

The specific aim of the demand management program was to reduce the average household water use, .inside and outside the house, by 20%. When combined with the likely increase in number of households in Melbourne, there would still be growth in total water use, but the growth rate will be slower and more manageable.

When the Tusk Force was established, the drought of 1982/ 83 had greatly increased community awareness of water issues through publ)c!ty and. water restrictions. The first demand management publtc1ty continued on smoothly from the end of water restrictions in December 1983. This has undoubtedly increased the effectiveness of the demand management campaign .

The task force was replaced by the State Liaison Committee on Urban Demand Management in August 1985, to encourage all urban water authorities in Victoria to accept responsibility for managing the demand on their own systems. The main role of the State Liaison Committee was the co-ordination and transfer of information, through the newsletter 'Water Watch', updating of the Streamline abstracting data base, preparation of brochures for smaller water authorities, and direct contact between committee

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26

WATER June 1991

members. The State Liaison Committee carried on this work until September 1989 (State Liaison Committee on Urban Demand Management, 1989).

The Board has been heavily involved in all stages of the program, and continues to play a leading role. Within the Board, coordination of the demand management program and development of future strategy is the responsibility of a line area. However, program implementation occurs across a number of areas to effectively utilise the wide range of expertise required.

RESTRICTION During the 1982/ 83 drought, formal water restrictions of varying severity were imposed for 12 months from December 1982 to December 1983. As in previous droughts, restrictions caused a substantial reduction in water use. The most severe restriction level scheduled could remove all the seasonal demand, plus about 150Jo of base demand, which would have given an overall reduction of about 380Jo in water use if applied for a full year. Restrictions were not at maximum level all year, and the actual reduction in 1982/ 83 was 270Jo (Duncan and Kesari, 1988).

After previous droughts consumption returned to expected levels in 12 months or less, but after the restrictions in 1982/ 83 only partial return to the pre drought trend occurred, as shown in Figure I. An interesting and important point is that with demand management, water restrictions will be less effective in future. Water saved once by demand management cannot be saved again by restriction. While this effect can be estimated, it has not yet been confirmed in practice. It must be fully allowed for in planning future resources and levels of service.

ADVERTISING

J

The major component of the Melbourne program visible to the general public is an ongoing advertising campaign, to affect the attitude of consumers to water supply issues. The effect on water use can be quite large, and can occur immediately. Water use in Melbourne was 150Jo below expected levels for two years after the end of water restrictions, but before the announcement of pricing reform. This reduction is due to change in consumer attitudes and behaviour, and is caused in part by advertising.

In the summer of 1983/ 84, advertising was centred around the slogan 'We can never take water for granted again', and was based mainly on newspaper advertisements featuring gardening personality Kevin Heinze. The following year introduced Wally the water waster in a successful ongoing television campaign using the slogan 'Don't be a Wally with water'. Bumbling Wally is now a well known television personality. Radio, local newspapers, posters, stickers, calendars, and brochures have also been used, and water conservation information has been included with the Board's rate notices. Major mass media campaigns have been undertaken again in the summers of 1988, 1989 and 1990.

Water conservation displays have been conducted at a number of venues, including the Royal Agricultural Show, the City Square, Garden Week, the Home Show and the 'Wally Weekends' at Burnley Horticultural College.

Several attitude surveys have been conducted since 1983 . Water . conservation is felt to be important by most respondents, and advertising recall is high. In 1983, during water restrictions, 980Jo thought water conservation was important. This had dropped slightly to 940Jo in 1986, compared with 840Jo for conservation of electricity and 820Jo for gas. In 1990, 900Jo of respondents supported advertising to promote water conservation, and awareness of Wally is almost universal.

The proportion of respondents who claimed to do things around the house to conserve water was 790Jo in 1990. Twenty per cent stated they had actually installed a water conservation device inside their homes, and 260Jo outside.

EDUCATION In conjunction with other demand management strategies, a comprehensive schools program was initiated in 1986. The aim was to introduce school children to water conservation, and to develop an appreciation of the value of water in everyday life. A program aimed at school children will hopefully influence attitudes in the longer term, but may also have a direct effect on the whole household. Educational programs developed so far include a water conservation play, a film on the water cycle for primary and lower secondary schools, and a classroom activity manual together with

supporting information. A program of s-ehool visits has been seen by about 5000 students each year (Duncan, 1989).

The Board has run workshops at conferences of the Geography Teachers' Association of Victoria, and at the Victorian Junior Science and Technology Festival, and has also undertaken in-service training of teachers.

A survey to evaluate the Board's education strategy was carried out by Ballarat CAE in 1988, comparing samples of students, teachers, and parents in Melbourne and Ballarat. It concluded that the strategy was soundly based and has had a positive impact.

Attitudes to water conservation were found to be a better predictor of actual behaviour than knowledge of water conservation issues.

Among the students surveyed, primary level students had the best attitudes to water conservation. A follow-up study has started this year.

GARDEN WATERING A survey of pre-drought water use by garden watering systems sh9wed that over-watering was common, due to the convenience of such systems, the dearth of reliable information on garden water requirements, and the lack of financial incentive to avoid waste under the old rating system (Duncan, 1987). In conjunction with the Irrigation Association of Australia, a program to develop and publicise garden watering needs has been developed. The program includes brochures for owners and installers of watering systems, television advertisements, and the highly successful Wally Weekends at the Victorian College of Agriculture and Horticulture at Burnley.

Households with fixed sprinkler systems, microspray systems, or drip watering systems all use more water on average than those relying on portable sprinklers and hand held hoses. The increase in water use is greatest for fixed sprinklers, and least for drip watering systems (Duncan, 1988). The water use of households with fixed sprinklers is now only half what it was before the drought, and on average is about the volume required to give good growth over the whole lawn and garden area.

HOUSEHOLD APPLIANCES Increasing the efficiency of water-using household appliances initially has only a small¡ effect on total domestic water use, as it takes time for the more efficient appliances to penetrate the market.

On the other hand the savings are certain, as they are not subject to changing attitudes, and wiH continue to increase until all households have replaced the older, less efficient appliances. State Supplementary Surveys of water using appliances, conducted by the Australian Bureau of Statistics in 1980 and 1985, provide base data on ownership and use of water using appliances.

The first appliance assessed in Melbourne was the toilet cistern, which accounts for about 180Jo of total domestic water use. After considering various options, a dual flush cistern giving an 11 litre full flush and 5.5 litre half flush was adopted. These were made compulsory in new and replacement installations from July 1984.

The average flush volume achieved in practice in a test area is eight litres, a saving of 270Jo over the single 11 litre flush. Ideal usage would give an average flush of about seven litres.

A reduced dual flush of 9/ 4.5 litres will be introduced shortly, and a further reduction to 6/ 3 or 6/ 4.5 litres could follow, subject to satisfactory sewer flow tests.

More recently, the Board has completed a detailed assessment of low flow shower roses. As part of the assessment, a water conservation rating and labelling scheme was developed. Shower roses which use less than 12 litres per minute (at 250 kPa) may display an A rating, while those that use less than nine litres per minute may display an AA rating (Beith and Horton, 1989).

The water use of all domestic water using appliances is being investigated, with a view to increasing efficiency and reducing water use. The potential savings have been assessed by Bugeja (1986). The effect on demand projections is described by Duncan (1991). The water conservation rating and labelling scheme currently applies only to shower roses and dishwashers. It will be extended to include other classes of water using appliances in future.

PRICING REFORM Pricing Structure The Board's domestic water charges are made up of two components - a water rate based on property value and a water consumption charge based on the volume of water used. The first move towards this system was announced in 1986. Under the WATER June 1991

27

previous system, the majority of consumers paid solely on the basis of a water rate based on property value, and therefore lacked any incentive to alter their water consumption habits.

Water conservation is a prime objective of pricing reform. Other important objectives are economic efficiency, equity between consumers with regard to both consumption and ability to pay, revenue stability, and simplicity (Greig and Lind, 1985).

The scheme as adopted comprised a water rate reduction of 15 0/o for domestic properties, and an increasing block pricing structure for water supplied by measure (Pinney, 1988). The pricing structure for 1986/87 was: 0 - 150 000 litres at O cents per 1000 litres 150 000 - 350 000 litres at 15 cents per 1000 litres > 350 000 litres at 45.6 cents per 1000 litres For the next two years, a gradual price increase (less than CPI) was accommodated within this structure. In 1989/ 90, the price of water in the second block (150 000 to 350 000 litres) was increased from 16.8 to 24 cents per 1000 litres. This price increase was offset by holding down the water rate so as not to increase revenue in real terms.

'Iwo further significant changes were introduced in 1990/ 91.

Firstly, the price of water in the lowest block (0 to 150 000 litres) was increased from zero to 15 cents per 1000 litres. Secondly, rates and charges will be combined on a single Board of Works bill to be issued from July 1991. To bring meter readings into line for the single yearly bill, two readings were necessary in 1990/ 91.

The major reforms to pricing since 1986 have been facilitated by extensive market research, impact analysis, consultation with other Government agencies, and public information programs.

Customer Response In 1984, 74% of respondents supported pay-for-use water charging, but this had dropped to 61 OJo in 1986. In 1988, 50% preferred the then current system of charging based on net annual value plus pay-for-use, and another 38% preferred a system where they pay a connection fee plus pay-for-use.

The latest research conducted late in 1990 found that 90% of the community were generally in favour of paying on a pay-foruse basis. At that time, there had been widespread community discussion of water pricing, and pay-for-use-pricing of other government services. The community is becoming steadily more familiar with the concept of volumetric pricing.

The largest drop in consumption associated with pricing occurred after the initial announcement in June 1986, but before bills under the new system were received. The drop in consumption in the first year was about 2% of total Melbourne consumption, after allowing for weather effects, in addition to the 15 OJo already achieved by consumer education. It is too early to assess the impact on water consumption of the more recent pricing changes. However, it is expected that these will reinforce and extend the reductions in consumption achieved to date.

It should be remembered in this context that the change in pricing structure in Melbourne was not accompanied by a price increase in real terms for the great majority of households. In fact , typical or average households now pay a little less in real terms, and there has been a net cost to the Board in changing from the previous system. Nevertheless, a more rational pricing structure is now in place, and the actual prices can in future give a more realistic message to consumers of the true cost of supply.

Water Conservation Assistance Scheme The Water Conservation Assistance Scheme was developed in conjunction with pay-for-use pricing. Consumers with queries about water conservation or the new pricing system were invited to contact the Board for further information and could request a Water Audit Kit. The Water Audit Kit provides information on efficient water use in and around the home, and in a step by step procedure estimates the present household water use.

The next step, if requested by the consumer, was a home visit by one of the Board's Water Audit Officers, who assessed the current water use and suggested where savings could be made. Where there was scope for significant reduction in water use, health card holders were eligible for a free retrofit program. This could include installation of a dual flush toilet cistern and low flow shower rose, and repair or replacement of leaking taps, as appropriate for the particular household. A significant attitude effect may also have been achieved, due to the information in the kits and the personal attention of the Water Audit Officers.

28

WATER June 1991

A study was set up to measure the actual change in water use resulting from the retrofit program. The average change in consumption was a statistically significant drop of 50 kL, or 170/o of expected consumption, in the first full year after the retrofit.

This increased to 60 kL (210/o) in the second year.

EFFECT ON WATER USE Seasonal Consumption The water use behaviour with demand management has been compared with expected behaviour under pre-drought conditions.

The expected consumption is obtained from a detailed mathematical model, which uses a wide range of climatic data and trend information to simulate the daily water consumption which would occur in Melbourne under the observed weather conditions if predrought behaviour still applied. The calibration and applicability of the model have been tested at length, and have been found to be satisfactory.

Before the 1982/83 drought, the observed consumption is close to the modelled (or expected) level, since the model simulated predrought behaviour. Since then, all components of water use have decreased. Mean annual water use dropped to 270/o below expected levels during restrictions, after which there was only partial recovery towards pre-drought levels. Total water use in 1985/86 was 150/o below expected, under the influence of appliance redesign and consumer education. Since the effect of appliance redesign can only appear slowly as new appliances penetrate the market, the 150/o reduction must be largely due to consumer education. The step from 15% to 170/o in 1986 appears to be associated with the announcement of pricing reform. The average reduction in total water use since stable post-drought conditions were established in 1985 is 16%. Winter use, which is largely domestic in-house and industrial use, has averaged 6% below modelled winter use since 1985. Summer use, which also includes domestic and non-domestic garden watering, has averaged 26% below expected levels.

The larger change in summer use is to be expected. Much of the earlier demand management effort was directed at garden watering, because it had the most scope for immediate improvement. There was little information on efficient watering available before the 1982/ 83 drought. There is less scope for reduction of winter demand, but pricing and appliance redesign are expected to achieve further savings.

After allowing for the effect of actual weather conditions, the new growth rate in demand is about 2% per year, compared with the pre drought growth rate of nearly 3% per year.

Peak Day Consumption Figure 2 looks at peak day consumption, which is the highest daily consumption in each financial year, and is important in the design of major water supply transfer and distribution works. A reduction of 20 to 30% has occurred, compared with expected values based on pre drought data. Peak day consumption is much more variable than the annual mean consumption, but overall the change is similar to the reduction in summer use.

3,500

;;-

3,000

~

i."' :I

2,500

2,000

C

0

iE

1,500

~

C

0 0

...

1,000

â&#x20AC;˘

~

.

Q

~

500

O

Before Demand Man age ment

*

With Demand Management

â&#x20AC;˘

AH trlcted

0.

-

0

¡ Trend Line Belote Demand Man ag' t

+-i-r-r-.,....,.-,--,-,.....,............,....,.....,...-,-,......,.....,....,.......,_,.............,....,.....,...-,-,.....,..~ 1966/67

1970/71

1975/76

1960/81

1985/86

1990/91

Fi nanc ial Year

Fig. 2 - Effect on Peak Day Consumption

Continued on page 31

CUSTOMER SERVICE. THE BOARD OF WORKS EXPERIENCE

by D. PATTERSON, Acting Manager of Customer Service SUMMARY The Board of Works has developed corporate objectives focusing on commercialisation, employee development and environmental management. A further objective has been to improve customer service. Surveys of a range of customers have identified areas of weakness.

Operations have been regionalised to be closer to the customer and staff, recruited from employees in all disciplines have been trained to utilise existing networks to respond rapidly to customer enquiries and complaints.

Regular surveys will continue and results are incorporated into management performance indicators.

ESTABLISHING THE OBJECTIVES The Board as an engineering organisation, has a long history of providing "technically" excellent essential services to metropolitan Melbourne, but it recognises that the provision of technically excellent services must be complemented by a willingness and capacity to talk to its customers, to respond to customer enquiries and concerns and to ensure that the Board's policies and practices meet the reasonable needs of its customers.

This has resulted in a decision to focus on customer service as an objective. A number of factors influenced this decision, including the Victorian State Government's Social Justice Strategy and its ministerial review of the Customer Policies and Procedures in the Revenue Division.

The Customer Service objective is "to improve Customer Service through developing the Board as a responsive, customer oriented organisation and by enhancing the community's understanding of the Board's role, its plans and policies".

In layman's terms: to provide customers with better service and more value for money through an improved assessment of their needs, better service delivery and improved communications.

COMMUNICATING 10 STAFF Having established these objectives it was critical to communicate them and have them accepted by the staff. It was important that the General Manager and other senior managers were seen to support the concept and to this end the General Manager developed an "aims" poster which was distributed to all sections.

This poster outlined: Our aim - "to contribute to the health and well being of the Melbourne Community by meeting open space needs and providing integrated water, sewerage, industrial waste and drainage systems in an efficient and effective, environmentally sound and socially responsible manner."

Documents such as annual reports and the General Manager's "Communications" carried the message supporting the customer service objective.

IDENTIFYING THE CUSTOMERS' PERCEPTIONS The next task required the Board to establish "Who are our customers? What services do our customers need? What are our customer's expectations? and how do they view the Board?".

Having compiled this information it was then necessary to take action to provide the facilities, support and training to ensure that the customer service objective was met.

MOVING CWSER TO THE CUSTOMER Line management reviewed procedures, policies and correspondence to make the Board more approachable and accountable. The existing five Regional complexes were expanded with many operations being moved from Head Office, so that regional managers and their staff took decisions closer to the communities served, thus enabling the needs of the customers to be more readily considered.

Customer service centres were established in Head Office and at each of the regional complexes to provide 'one stop shop' information centres. The Board strategy was to focus the customer 30

WATER June 1991

service centre's direction toward easily accessible 'counter type' operations which could handle the majority of customer enquiries.

TRAINING It was necessary to recruit staff with specific customer service

skills. Incentives were offered to attract the most suitable employees and these included: • rates of pay one/ two levels above the established level • opportunity to work in a high profile area • new accommodation and modern facilities • uniforms To ensure that the 'one stop' operation was provided it was important for staff to become multi-skilled so they were able to handle all enquiries with a minimum of assistance.

Consultants worked with staff and customers to identify customer service issues and developed training strategies appropriate to Board staff. A training manual was produced and volunteers participated in a Train-the-Trainer program so a Service Enhancement Program could be conducted throughout the Board. This program is not specific to administrative officers, technical staff or field staff, but covers the broad issues of customer service. Staff involved are encouraged to identify what they see as barriers to customer service and the course allows participants to utilise existing networks and strategies to better respond to their customers.

REINFORCING THE MESSAGE The message that customer service is a major objective of the Board was continually reinforced by publications such as "Frameworks for the Future", which is issued annually by the General Manager and lists.the major projects to be undertaken within the planning period, the action to be taken, the responsible executive and the completion date. For customer service these included: • developing a social profile of the Board's customer with a view to preparing a social issues strategy; • developing a three year program for the regular tracking of customer and community views, perceptions and actions; • review of current water supply and sewerage levels of service; • complete regionalisation of nominated functions and services.

MONITORING THE PERFORMANCE The first customer monitor survey was conducted in 1988 by means of 600 in-home personal interviews. The results of the survey revealed the following: • those who had had reason to contact the Board were generally satisfied with the response they had received and commented positively about promptness of service, friendly, helpful staff and the rectification of problems.

• nearly half the sample considered the Board's charges were about right for the services it provided. In terms of cost/value perceptions, the Board rated equally with the Electricity Commission, better than Telecom but below the Gas Corporation.

• the Board was held in less regard in the areas of cost efficiency and management.

It was there that the opportunity for improvement lay.

The second customer monitor survey, conducted in 1989 utilised 300 telephone interviews, and the results were similar to the first: • the majority of customers (65%) contacting the Board were satisfied with the response to their needs.

• the Board was seen as being reasonably concerned about its customers (61 OJo compared to 540Jo in 1988).

• the Board could still make improvements in the perception of its efficiency in the area of finance and responsiveness.

The third survey, conducted in August 1990, again used the telephone. The number of interviews increased to 500 resulting in confidence intervals of ± 30Jo. With regard to response to a need the results were similar to previous years with 650Jo of those who contacted the Board being satisfied.

However, the image of the Board was less favourable. It was less likely to be perceived as financially sound and well-managed. It

is believed this was due in part to the economic problems of many government agencies and the plight of numerous private sector companies, which was directly affecting a high number pf households.

Further analysis of those who were satisfied with the Board response to their need showed that the main reasons for the satisfaction were: • prompt response • job well done/effectively • obliging/ helpful/courteous workers.

The 350Jo who indicated that they were not at all or not very satisfied did so because of: • the unsatisfactory/ incomplete information/service given • the slow response.

Despite the initiatives taken over the previous three years, satisfaction with customer service had remained constant at the 65 OJo level. It was decided to undertake a specific study to provide a more accurate measure of customers who had contacted the Board.

A total of 404 telephone interviews were conducted from a list of customers who had contacted the Board (other than for rate enquiries and site inspections) within the month of August 1990. · The results of this survey revealed that a clear majority of customers contacted were satisfied with the Board's response to their problem or enquiry, with 780Jo giving a 'quite' or 'very satisfied' rating.

Satisfaction tended to stem from speed and effectiveness of service.

The minority (21 OJo) who were dissatisfied gave the following as their reasons: • slow response or took several phone calls • problem not yet fixed or keeps recurring • unsatisfactory service.

Sixty-eight per cent rated the Board's speed of service as very good or good (with 460Jo giving the former rating) 930Jo rated the

H.P. Duncan Continued from page 28 EFFECT ON PROJECTIONS AND COSTS Figure 3 shows recent annual consumptions, a projection of demand from the 1981 Water Supply Strategy Report (Langford, 800

/

:;

700

~

-;

......···' 600

,,·······

c3"'

./

500

;

,,······

Present Safe System Yield

./

../ .,.,,,,..,.,,,,,..,,,.

------

E

as $75M if a vigorous campaign is maintained for a number of years.

If longer time horizons were used, and effects such as reticulation design and power costs were considered, the saving would be even greater. The demand management campaign has thus been highly cost effective.

Demand management programs in the three large Australian cities cited here have effectively reduced water demand and deferred future system augmentations. The present value of savings due to works deferred is substantial, and the demand management programs have been highly cost effective. The cheapest water available in future may well be the water which was wasted in the past.

REFERENCES

C

.2 1i.

THE NEXT STEP The culture of the Board has changed and the surveys conducted support the view that it is on the right track. To further enhance the service provided the Board is now focusing on updating its information systems to make them more user- and customerfriendly.

CONCLU8IONS

/

:..;

Board's staff as being very or quite helpfu-i when they made initial contact with the Board. Twenty-six per cent claimed they had to contact the Board more than once to get the problem attended to.

The survey indicated that a higher percentage of customers were satisfied with the Board's response to their problem than the previous survey (780Jo compared to 650Jo). This was probably due to the fact that the survey was solely service- related and customers opinions were not being clouded by current economic problems etc.

The survey provided valuable information regarding reasons for customer dissatisfaction.

With this information, the performance contracts for the Assistant General Manager, Customer Service and the Regional Managers have been amended to include customer service satisfaction as a key performance indicator. The measurement of performance for this indicator is by monthly telephone survey. There are 20 interviews conducted for each of the following activities each month: • plumbing services - covering site inspections, bookings etc.

• emergency services.

• development services - covering developers,contractors • general enquiries - covering over-the-counter interviews, correspondence and telephone.

The survey results will be released as a three month rolling average, with the period January to June 1991 being used to establish appropriate targets.

400

~ ~

1981 Strategy 1990 Current Campaign

C

0

CJ

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0--------0

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1990 Full Campaign Actual Consumption

ee

1-r"T"T"T"T"T"T"T"T"T"T"T"T"T"T"T"T"T"T"T"T"T"T"T"T"T"T"T"T"T"T...,...,...,...,...,...,...,...,...,...,...,...,,-,-1

80181

85186

90191

Fig. 3 -

95196

2000101

05106°

10111

15116

20121

Projections of Demand

et al, 1982), and two 1990 projections based on two different levels of future demand management. A headworks augmentation would have been needed in about 1998, according to the 1981 projection.

The current moderate demand management campaign has deferred that date by six years to 2004. A full and vigorous demand management campaign could probably defer the augmentation date another ten years to 2014, a total of 16 years.

If a notional capital augmentation cost of $150M and a discount rate of 40Jo are assumed, the six year deferral of head works already achieved has a present value (in 1991) of $32M. If the lower projection can be sustained in future, the resulting 16 year deferral has a present value of $52M. If a peak day reduction of IOOJo is adopted for timing of future works, saving in regional distribution works over the next ten years has a present value of about $23M. Counting only the effects described above, the present value of demand management is already at least $32M, and could be as high

BEITH, I. J. and HORTON, D. J., (1989). Water Use Efficiency of Domestic Appliances. Urban Water Research Association of Australia, Research Report No. 7.

BROAD, P.A., (1985). Water Pricing - The Hunter Experience. Reform of Urban Water Tariff Structures, a joint seminar by Victorian Water and Sewerage Authorities Association , Institute of Water Administration, and Victorian Department of Water Resources, Ringwood.

BUGEJA, R. M., (1985). Task Force on Urban Water Demand Management, Achievements 1983-1985. Department of Water Resources, Victoria.

BUGEJA, R. M., (1986). Forecasting and Managing Urban Water Demand in Victoria.

Department of Water Resources, Victoria.

CLARKSON, P. J., et al., (1985). Domestic Water Use in Perth, Western Australia.

Water Authority of Western Australia.

DUNCAN, H.P., (1987). Monitoring of Urban Water Demand . First Progress Report.

Melbourne and Metropolitan Board of Works Report No. MMBW-W-0080.

DUNCAN, H.P., (1988) . Domestic Drip Watering Systems in Melbourne. Proceedings of the Fourth International Micro-irrigation Congress, Albury-Wodonga.

DUNCAN, H. P., (1989) . Position Paper on Consumer Education. Urban Water Demand Management Seminar, Sydney.

DUNCAN, H.P., (1991). A Review of Water Consumption and Demand Management m Melbourne. Board of Works Water Supply Division.

DUNCAN, H.P., and KESARI, N., (1988). Planning and Management of Melbourne's Water Supply System. National Workshop on Planning and Management of Water Resource Systems, Adelaide.

GREIG, P. J. and LIND, J. J., (1985). MMBW Water .Pricing Study. Reform of Urban Water Tariff Structu_res, a joint seminar by Victorian Water and Sewerage Authont,es Assoc,auon, Insutute of Water Administration, and Victorian Department of Water Resources, Ringwood.

HEEPS, D.. P., (1986). Water Demand Management in Melbourne. Irrigation Assoc1at1on of Australia Nauonal Symposium, Canberra.

LANGFORD, K. 1;, et al., (1982). A Water Supply Strategy for Melbourne, Planning for an Uncertain Future, 1echnical Report. Melbourne and Metropolitan Board of Works Report No. MMBW-W-0075.

PINNEY, R. E., (1988). Tariff Reform - MMBW. State Liaison Committee on Urban Demand Management Seminar, Lakes Entrance.

State Liaison Committee on Urban Demand Management, (1989). Final Report, August 1989.

WATER Jun e 1991

31

Application of Deep Bed Filtration in Tertiary Wastewater Treatment

by S. VIGNESWARAN INTRODUCTION Deep bed (or granular bed) sand filters have been used as the final clarifying step in municipal potable water treatment since the beginning of the century. Their use is becoming important in wastewater treatment in tertiary treatment stage as effluent standards are becoming increasingly stringent. Most of the wastewater treatment plants incorporate deep bed filtration (with dual media arrangement) in the tertiary treatment step to remove part of the remaining BOD and suspended solids.

If flocculation with alum or iron salts is incorporated prior to filtration, the removal of suspended solids and BOD will be improved while also achieving phosphorous removal. Flocculation can either be achieved in a separate tank prior to filtration or in the filter itself by direct feeding of flocculent. The latter arrangement is known as contact flocculation - filtration (CFF) where both flocculation and filtration occur within the filter bed. CFF saves capital cost since it needs only a chemical holding tank in addition to the filter, but CFF suffers from the drawback that the filter bed becomes clogged very rapidly and frequent backwashing is required.

A mobile bed filter (MBF) which incorporates continuous washing of sand is a good alternative when CFF arrangement is used, to avoid frequent washing.

The objectives of this study were therefore, to compare the effect of different filter media with the CFF arrangement. To overcome the problem of frequent backwashing when CFF is used in deep bed filtration, mobile bed filter (MBF) experiments were also conducted in this study and the results obtained are discussed.

EXPERIMENTAL SET-UP AND INVESTIGATION Fixed bed experiments were conducted by using a semi pilot-scale deep bed filter as schematized in Figure 1. Figure 2 shows the schematic diagram of the MBF experimental set-up. Figure 3 shows the details of MBF column. The oxidation pond effluent of AIT sewage (Sewage from Asian Institute of Technology, Bangkok) was used. Since the effluent was low in BOD and SS, to represent the effluent from secondary treatment it was mixed with AIT raw sewage at 1:1 ratio (VIV). Table 1 presents the characteristics of wastewater used in this study.

Dr. S. Vigneswaran is presently a Senior Lecturer in the &hoof of Civil Engineering, University of Technology, Sydney. He graduated BSc (Hons) in 1975 from the University of Sri Lanka, and MSc in environmental engineering in 1978from the Asian Institute of Technology. He was awarded the degree of Docteur lngenieur in 1980 and Docteur es Sciences degree in 1987 in the field of chemical engineering from the Universite de Montpel/ier, France and Jnstitut National de Polytechnique de Toulouse, France respectively.

I S. Vigneswaran

Table 1 - Characteristics of the wastewater used in this study.

Concentration (average)

Parameter

46

Turbidity (NTU) Suspended Solids (mg/ I) COD (mg/ I) BOD (mg/ I) Phosphorus (mg/I) TKN (mg/ I)

18

54 23 2 11

The performance of filter in treating this wastewater was studied for different filter media (dual media and single medium filter).

Experiments were conducted with and without addition of flocculents. Alum was used as flocculent. Z.Ctag-2 (cationic polymer) was also added with alum to aid flocculation . The experimental conditions used are given in Table 2.

RESULTS AND D_\SCUSSION Fixed Bed Filter Experiments Experiments conducted (Runs A and B) on the effect of flocculents (Alum and Z.Ctag-2) showed that the flocculent improved removal efficiencies in terms of turbidity, COD and phosphorus

e 125 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

0250

I @

<D

Storage tank Pump Constant head tank Flow meter Mobile bed filter Head loss board Alum feeding pump Alum feeding tank Air compressor Air control valve Inflow control valve Effluent outlet Sand washing compartment Eff luent tank Sludge outlet

6

(Unit in cm)

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

Storage Tank, capacity 1.5 m3 Lift Pump, capacity 0.5 Uh, maximum head 3.7 m Constant Head Tank, capacity 10 L Flocculant Storage Tank, capacity 15 L Flocculant Feeding Pump, capacity 1 Uh Filter Column Tank, 10 cm diameter, 200 cm length Piezometer Rotometer Flow Rate Controller (Gate Valve) Backwashing Line Fig. 1 -

32

WATER June 1991

Experimental Set-up

12 5

Fig. 2 - Schematic diagram of experimental set-up for mobile bed filtration

Table 2 - Operating conditions of different experimental runs.

Media

Exp.

Filter

Run

Media

A

Sand

B

Sand

C

A nthracite Sand

D

A nt hracite Sand

Media size

E = U = E = U = E = U = E = U = E= U = E = U =

1.0 mm 1.1 5 1.0 mm 1.15 1.54 mm 1.15 0. 77 mm 1.1 5 1.54 mm 1.15 0.77 mm 1.1 5

100

Depth

Operation

Filtration velocily*

(cm)

mode

(m/ h)

120

Constant rate

IO

Witho ut

120

Constant rate

IO

With

60

Consta nt rate

IO

Witho ut

Flocculent

addition

t

80

60

-Run A 40

-

60

Run B

--+-RunC

60 Constant rate

IO

20

Wi th

60

-

RunD

0 0

*) initial fi lt rat ion velocit y t 150 mg/ I of alum + 0.50 mg/ I of zetag-32

2

4

10

8

6

Time (h)

E :;,:; effecti ve size U = u nifo rm it y coeff icie n t

Fig.

4-

Variation of Turbidity Removal with Time

Sand woshlnc,i comportment 0100 Acrylic tube

70 , - - - - - - - - - - -- - - -- - --

lg

Effluent tonk

-

~

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0 0

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Runs

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jg

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E

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o

Fig. 5 -

~ Q

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......

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:> 0

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MBF Experiments A mobile bed filter which incorporates continuous washing of

6

8

0

.,E

10

.

Variation of COD Removal with Time

r

::l

Sectional view of MBF

(Figures 4, 5 and 6). The optimum doses of alum and cationic polymer (Zetag-2) were 150 mg/ L and 0.50 mg/ L respectively, determined from short term filtration experiments (1 hour filter run). The filter removal efficiency in terms of turbidity and phosphorus was used as criterion to determine this optimum dose.

Due to time constraint, filter runs of long durations were not conducted with lower alum doses. Although the filter removal efficiency was higher in the case of CFF arrangement, the filter run length was reduced significantly due to the high headloss development (Figure 7). The reason for high headloss development in CFF arrangement could be explained by Figure 8, which shows the headloss distribution along the filter depth at different filter run times. This figure clearly shows that the particles removal is confined to the top layer in the case of sand filtration with CFF arrangement. To overcome this shortcoming of short filter run time, experiments were conducted with dual media consisting of sand and anthracite as filter media (Run D). The removal efficiency in terms of turbidity, COD and phosphorus was better than the single medium (Figures 4, 5 and 6) while the headloss was less and more distributed throughout the filter depth (Figures 7 and 9). A dualmedia filter experiment was also conducted without flocculent addition (Run C) . In the latter case, although the headloss development was very much less, the removal efficiency was inferior to that with CFF arrangement.

In all the fixed bed filter experiments with CFF arrangement, the filter runs were very short. To overcome this problem, Mobile bed filtration (MBF), in which dirtiest sand is cleaned and recycled in a continuous manner was tried in place of fixed bed filter.

100

~

25

~

4

Time (h)

100

Fig. 3 -

2

All dimensions in mm

-Run A -RunB --+- Run C - - RunD

40

0...

CJ') 0

..c::

20

P...

~

0 0

2

4

6

8

10

Time (h) Fig. 6 - Variation of Phosphrous with Time

,-...,

s

150

~ CJ) CJ)

0

1 00

~

<1l

Q)

::r::

50

0

2

4

8

10

WATER Jun e 1991

33

6

Time (h) Fig 7. - Variation of Headloss with Time

Experiments done to find the effect of wltration rate showed that there is no effect on the removal efficiency of the parameters COD, turbidity, phosphorus and nitrogen . Removal efficiency of nitrogen was very low as 10-150Jo . Headloss was higher for higher flow rate but still it was only 15 cm. There was no headloss development and it remained almost constant throughout the run.

Therefore it is economical to operate at a higher filtration rate thus saving capital cost. Removal efficiencies of COD, T-P and turbidity are given in Table 4 .

A set of experiments was done to find the effect of polyelectrolyte addition on removal efficiency which showed that there is not much improvement by adding polyelectrolyte. Polyelectrolyte sticks to sand grains which caused difficulty with the backwashing.

0 20

-s 3 ..c:

40 60

p.. 80 (l)

Q100 120

t= Oh

t = 0.5 h

Table 4 - Performance of MBF.

t=lh

140

Average remova l efficiency

0

E

40

80

200

160

120

Head loss (cm)

=

Fig. 8 - Headloss Distribution (filter medium sand: 1.0 mm; U 1.15) with contact-!loc~ulation filtration 10m Im h arrangement; V

=

=

=

20 40

---us --,fl

Anthracite layer 6 0 - l - t r - - - ~ -_____:::,"*=:::-_ _ __

_

_

--l

Sand layer 80

0..

t = 2.5 h

CJ

0100

t = 1.0 h

120-+--,--,j--.--.....--+-,.--..---.---.---,,......-1 0 40 80 120 160 200

Headloss (cm) sand is a good alternative when CFF arrangement is used, to avoid frequent washing.

MBF normally operates on a continuous basis whereby sand media slowly falls down or moves up at an angle, depending on the design across which the wastewater passes. Wastewater flow direction can be upwards or downwards or radially depending on the design. As the suspended solids are removed, the sand gets dirtier until it reaches the bottom from where it is recycled by air lift or by hydraulic means, to a cleaning system at the top of the column.

After washing, sand falls to the top to recommence its downward movement. In MBF, the most important operating parameters are the sand recycling and sludge withdrawal rates which determine the removal efficiency and economy of operation of the filter.

From the experiments conducted in this study, for the laboratoryscale mobile filter unit used, the sand recycle rate of 190 ml/min and sludge withdrawal rate of 160 ml/min were found to be the most effective giving the highest removal efficiency and steady performance.

The Schedule of experiments carried out in this study is given in Table 3.

Table 3 - Operating conditions of MBF experimental runs conducted with wastewater [filter media: Sand of size 0.6-0.84 mm] Filtration velocity (m / h)

Sand

Sludge

recycle

withd rawal

rate* ('lo / min)

(cm'fJ!in)

E F G H

2.5 5.0 7.5 7.5

0.756 0. 756 0.756 0.756

160 160 160 160

â&#x20AC;˘ 150 mg/ I Alum + 0. 5 mg/ I zetag-32 150 mg/ I Alum onl y t Calcu lated in term s of O"/o o f filter sand volum e recycles/ min

t

34

WATER June 1991

E F G

2.0 1.0 6.9

92 93 90

17.7 16.6 18.4

68 70 78

0.7 0.5 0.2

70 90 90

0.6 0.7 0.4

7 lJ 13

5 II

15

From these results, it can be noticed that the turbidity and phosphorus removal efficiencies are sufficient but that removal of dissolved organics and nitrogen was not sufficient if one wants to reuse the effluent.

Although MBF produces an effluent of good quality with practically no headloss development, the use of an air compressor to recycle the sand to the top layer of filter medium results in additional energy cost. Based on the results obtained, a sample calculation was made to design a MBF for a small population of 250 people with per capita sewage production of 250 L/d. This calculation led to a daily energy requirement of 45 kWh . This cost is not high when compared to the amount of filtered water necessary for backwash (approximately 30Jo of daily water production per each backwash) and cost involved for operation and maintenance of conventional sand filters. MBF is continuous in operation and requires very little or no supervision.

CONCLUSlON

Fig. 9 - Headloss Distribution through Dual Media Filtration [Filter media: Sand (E = 1.0 mm, U = 1.15) and Anthracite (E = 1.54 mm, U = 1.15))

Exp. run

COD T-P TKN Maximum Effluent 'lo Efflu ent 'lo Effl uent 'lo Effluent 'lo headloss (NTU) removal (mg/ I) removal (mg/ I) removal (mg/ I) removal (cm)

Turbid ity

Exp. run

Flocculent addition

Dual media filter with CFF arrangement removes turbidity, COD and phosphorus from secondary effluent of sewage. The main problem of this treatment system is, however, the frequent clogging of filter bed which necessitates frequent backwash of filter. MBF with CFF is a good alternative as it produces as good quality of effluent as that of sand filtration in a continuous manner with no headloss development. Although the energy requirement is higher in the case of MBF operation, this is offset by the lower amount of water necessary for backwash in the conventional sand filter.

REFERENCE VIGNESWARAN, S. and BANDULAHEWA, R. (1990) Applicability of Mobile Bed Filtration in Reuse of Domestic Wastewater, Project Report, CIDA-AIT Partnership Project, June 1990.

CONFERENCES

IAWPRC Appropriate Waste Management Technologies 27-28 November 1991 Waste Treatment by Algal Cultivation 29 November 1991 Murdoch University Perth

INDIAN W.W. ASSN. Rural Water Supply and Sanitation for Developing Countries 4- 7 January 1992 Nagpur, India CALL FOR PAPERS Abstracts as soon as possible to Dr Goen Ho, Murdoch Uni, Perth, for forwarding to India.

Conference Registration Fee US$200

ALICE SPRINGS THE MEREENIE SANDSTONE AQUIFER P. B. JOLLY, G. W. PROWSE and D. N. CHIN ABSTRACT

Peter Jolly is the Principal Engineer, Groundwater, in the Water Resources Division of the Northern Territory's Power and Water Authority. He has 17 years experience in water resource investigations, specialising in ground water.

Alice Springs currently draws the water supply from the Roe Creek Borefield, 15 km to the SSW. Hydrogeological analysis and computer modelling indicate that the water is being drawn from local storage, and that the lifetime of the borefield, with present practices, is limited.

INTRODUCTION Alice Springs is located close to the geographic centre of Australia (Refer Figure I) . With a mean annual rainfall of 285 mm, the area is only moderately arid. The majority of this rainfall falls in the summer when temperatures are above 30°C. Potential evapotranspiration has been estimated at between 1250 and 1500 mm per year (Mabbutt). · Alice Springs prior to 1964 sourced its water supply from alluvial sediments deposited by the Todd River. Since 1964 most of its water supply has been sourced from an aquifer in the Mereenie Sandstone located adjacent to the banks of Roe Creek 15 km to the southsouthwest.

The Mereenie Sandstone is one of the formations that comprise the Amadeus Basin. The Roe Creek Borefield is situated at the eastern end of an east-west trending broad syncline which may be considered in a groundwater context as a continuous series of discretely or poorly interconnected aquifers with a regional groundwater flow from west to east.

P.B. Jolly

Daryl Chin is a Groundwater Engineer in the Water Resources Division of the Northern Territory's Power and Water Authority. He has four years experience in the investigation and evaluation of groundwater resources.

D.N. Chin

5 metres. The chemical quality of water is good, with a total dissolved solids of 600 mg/ L and hardness of 210 mg/ L.

THE ROE CREEK BOREFIELD

BOREFIELD HYDROGEOWGY

Currently in excess of 80% of Alice Springs water supply is extracted by 16 production bores constructed in the Mereenie Sandstone. The major producing aquifer in the region is and will continue to be the aquifer developed in the Mereenie Sandstone.

Annual extraction from the Roe Creek Borefield is 10 million m 3 pumped from as much as 170 metres below ground level.

Peak daily consumption approaches 55 000 m 3 . Individual bores may yield in excess of 8000 m 3 per day with well losses of less than

Aquifer development in the vicinity of the borefield has been controlled by the extent of fracturing and deep,chemical weathering associated primarily with the "mountain building" event known as the Alice Springs Orogeny which took place about 350 million years ago. A deep valley feature existed to the west of the borefield, south of Iwupataka, during this period apd intense fracturing of the sandstone to the west of Roe Creek is most likely associated with chemical weathering and "mass" wasting along the flanks of this valley.

(Condensed from a paper presented at AWWA Conference "Achieving New Standards in the Territory" Darwin August 1990).

LE GEND A-- B

O£OLOGIC1t.t

CROSS S[CTIO"I

DEVONIAN TO CARBONIFEROUS

P.,1n1&1a G<ou1> ,nclu<1,n11 He1111anna1>u111Sand11one

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~-1000

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35

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GEOLOGICAL CROSS SECTION CO

55

S

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Fig. 1 -

36

WATER June 1991

30

35

40

0

SD

55

60

K•lomet,es GEOLOGICAL CROSS SECTION AB

65

70

-

no-

F0LO,llll $

PROTEROZOIC

POTENTIOMETRIC

PROTEROZOIC TO PALAEOZOIC

LEY H

CO NTOURS

(l'ftAI-IO)

Regional hydrogeology of study area

A1un11Comole •

p(:LJ

In the Borefield the Mereenie Sandstone has a true thickness of 365 m. Jolly et al (1990) have sub-divided it into three hydrogeologic units - A (first deposited), B and C. Unit A represents the sediments deposited as the environment of deposition changed from marine to arid terrestrial. It is 150 m thick. Unit B was deposited in extremely arid conditions. It has a thickness of 1()() m. Over most of the Amadeus Basin this unit has the highest permeability and porosity. Formation stability problems are often encountered in this unit. Unit C was deposited as the environment changed from extremely arid to very wet and humid. It has a thickness of ll5 m.

Normally this unit only yields moderate supplies except for a small area to the west of Roe Creek, where most of the production bores are. In this area internal fracturing due to the valley feature described earlier has resulted in it being a very high yielding zone.

Permeability and porosity are at their maximum near outcrops where unloading due to erosion and chemical weathering are greatest. Hydraulic conductivities of 0.02 to 0.1 cm/ sec and porosity values averaging in excess of 220Jo have been measured in the borefield. Data from oil wells indicate that at depth significant hydraulic conductivity (10-4cm/ sec) and porosity (10%) only occur in Unit B.

TIME ( years) ~

II)

~:

(ll

(ll

Cll'O>

4484~

( EAST OF 0 BOREFIELD) 48Q3

10

10

12

12

14~

]: 1-4

~

16

0

18

a

.. .

~ 20

0

<

0

~ 22

,.

24 26

28 28

2

o AC TUAL ORAWOOWN 3537 â&#x20AC;˘

28

MODE L ORAWOOWN 3537 --ACTUAL ORAWOOWN 30

30

--MODEL ORAWOOWN

32

32

34

34

38

1000

10000

DISTANCE FROM PUMPING

100J3o

CENTRE (m)

Fig. 3 - Comparison of model and measured drawdown data

BOREFIELD MODELLING

for a range of recharge and discharge rates (natural, by evapotranspiration or stream flow, not pumping), and a range of hydraulic parameters by reproducing the known regional water levels as shown in Figure 1. A period of 1000 years and recharge rates over areas of outcrop of 10 mm/year were utilised. This modelling confirmed the correctness of the hydraulic parameters used in the Borefield model and hence the deduction that the majority of water was being extracted from local storage, or, in other words, mining of the resource.

For the current extraction rate of 10 million m 3 per year, inputs into the system from recharge, up-dip flow and across-strike flow are only of the order of 0.5 million m 3 per year.

The major conclusion that could be drawn from the modelling exercise was that if the majority of water was being extracted from local storage then a linear relationship should exist between drawdown and the cumulative extraction from the Mereenie Sandstone. A plot of this data confirmed that this relationship did

Computerised models have been developed to predict the future performance of Roe Creek Borefield. The models have been developed using MODFWW, a three dimensional modular finite difference groundwater flow model.

The borefield model covered an area of 351.75 km2 (refer Figure 2) and was calibrated against extraction and water level data existing for the period 1961 to 1975 . The model was verified using data for the period 1975 to 1985. (refer Figure 3). The major output of the model was that the majority (in excess of 95%) of water extracted was coming from local storage. To verify that this was indeed correct a regional model was established.

REGIONAL MODELLING Again using MODFWW, a computerised model was established to represent the 9600 km encompassing the aquifer in the Mereenie Sandstone for the area shown in Figure 1. The model was calibrated

Continued on page 41

\

-

ROE CREEi( BOREFIELO PRODUCTION BORES

0

REGtONAL MON ITOR IN G BORES INFERRED GEOLOGICAL BOUND ARV Of OUT CROPPING OR SUBCROPPlNG MER E( NIE SANDSTONE

D D

BOUNDARY Of MODEL

AREA Of UNCONFI N ED ~OUIFER WllHIN M ODEL

AREA OF CONF I NED AQUIFER WITHIN MOD EL

-

INA CTIVE NODES WITHIN M ODEL

PROPOSED FUTURE BOREFIELD IN ROCKY HILL AREA A S RECO MME NDED VERHO E VEN 1979

Fig. 2 - Roe Creek borefield and local model WATER June 1991

37

TECHNICAL NOfE

Energy requirements for ·pvc and Ductile Iron Pipe Dr A WILLIAMS, Associate Professor of Mechanical Engineering, Monash University Federal, state and local governments throughout Australia are becoming increasingly aware of the need for using energy efficiently.

Concern about the greenhouse effect has led governments to look closely at the energy consumed by all sectors of the economy, including manufacture, distribution and operation of goods and systems.

This article reports the results of a detailed comparison of the types of medium pressure piping used in municipal water reticulation systems. This study examined the energy required for manufacture and the associated greenhouse gas emissions. It has produced some unexpected results.

PVC AND DUCTILE IRON-AN ENERGY COMPARISON . The 'energy of manufacture' was compared for two sizes of PVC and ductile iron (DI) pipes: 100 and 150 mm nominal diameters, for pressure ratings of 2 MPa. The PVC pipe specification is given in AS 2977-1988 as Class 20, and the ductile pipe is specified as AS 2280-1988 Class K9 for comparable uses.

The objective of this study was to obtain reliable energy data in order to evaluate several recently published claims 1•2 about relative energy requirements for PVC and ductile iron pipe. These claims state that manufacture of ductile iron pipe requires seven times as much energy as manufacture of PVC pipe. As the author was unable to obtain published energy data to support these claims, a technical comparison was undertaken of current methods of production of the two types of pipe.

Regarding the comparison of ductile iron with other systems, it should be realised at the outset that the ductile iron pipe is made entirely from iron and steel scrap. As there is no production of 'new' iron or steel involved, the energies associated with those production processes have not been included.

Energy data on manufacture of ductile iron pipe was based on energy records provided by Tubemakers of Australia Limited from their Yennora, NSW plant. These records showed use of electricity, gas and coke and the associated output of ductile iron pipe. Over several years, the average purchased energy required for transforming the scrap into pipe has been 16 GJ per tonne of pipe.

When the electricity component of this input is converted to its primary energy equivalent it results in a total energy manufacture of approximately 23 OJ per tonne. On a length basis, this is approximately 0.37 OJ per metre, for 100 mm nominal diameter Class K9 ductile iron pipe.

The energy or production (or manufacture) of PVC pipe ranges between 60 and 70 GJ per tonne in several countries 3 • This figure includes energy inputs in the form of electricity, gas and oil. To obtain a total primary energy input, the electricity component of this input is converted to its primary energy equivalent, assuming 330Jo generation efficiency. The total primary energy input becomes approximately 117 OJ. When this is calculated on a pipe length basis, the primary energy of production is 0.66 OJ per metre of pipe for 100 mm nominal diameter Class 20 PVC pipe.

The ductile iron pipe requires less than 600Jo of the energy used in manufacture of an equal length of PVC pipe. This finding is in direct conflict with the previously cited claims related to manufacture of PVC and ductile iron pipe.

Ductile iron pipes are frequently provided with a lining of cement mortar. Although this considerably increases the mass per unit length of the pipe, it results in only a 20Jo increase in the energy required for manufacture. The energy of production for cement is only 1.3 OJ per tonne, so it adds little to the overall energy requirement for ductile iron pipe. The comparison given between energy requirements for PVC and ductile iron pipe is therefore still valid for lined pipe.

The previous analysis was made for 100 mm pipe. A similar analysis made for 150 mm pipe (Class K9 ductile iron and Class 20 PVC) showed an even greater energy advantage for ductile iron pipe. The energy of manufacture of 150 mm ductile iron pipe was only 420Jo of that required for manufacture of PVC pipe of equal 38

WATER June 1991

length . Further increase in pipe diameter accentuates this energy benefit to ductile iron pipe.

A comparison was also made for a lighter grade of PVC pipe.

This compared 100 mm Class 12 PVC (which is rated at a maximum working pressure of 1.2 MPa at 20°C) with ductile iron K9 pipe (rated at 4 MPa). This comparison showed ductile iron again required only 800Jo as much primary energy for manufacture as did PVC. A final comparison was made between 150 mm Class 12 PVC and K9 ductile iron pipe. The ductile- iron pipe required approximately 620Jo as much energy for manufacture as the PVC pipe.

The above comparison relates only to the energy used in the manufacturing process. Subsequent transportation and assembly energy costs are larger for ductile iron than for PVC in the DNlO0 & 150 mm diameters which were the subject of this study. In energy terms, however, the difference is less than about 30Jo.

GREENHOUSE GAS EMISSIONS The greenhouse gas emissions resulting from the manufacture of pipe can be determined by calculating the emissions associated with each different type of energy. The carbon dioxide produced per unit of electrical energy varies between states, because different fuels are used in generating electricity. For equal energy outputs greenhouse gas emissions from electrical energy are high compared with those from fossil fuels. This occurs because power generation is only about 330Jo efficient (that is only 33% of the energy is produced as electrical energy; the remainder being lost as heat).

Manufacture of PVC requires considerably more electrical energy than ductile iron per tonne of material. It is therefore at a disadvantage in emission of greenhouse gases.

Using the emission coefficient for electricity produced in New South Wales, manufacture of 100 mm ductile iron pipe results in approximately 800Jo of the greenhouse gas emissions produced by manufacture of comparable PVC Class 20 pipe. Manufacture of 150 mm ductile iron pipe results i9- approximately 600Jo of the greenhouse gas emissions produced by manufacture of comparable PVC pipe.

OTHER ENVIRONMENTAL EFFECTS Ductile iron pipe uses only ferrous scrap as its primary feedstock.

No steel or ironmaking is directed toward the production of this type of pipe. This means than only material which would otherwise be 'waste' is used in manufacture. This is clearly environmentally attractive.

CONCLUSIONS The 'primary energy of production' for making ductile iron piping for conventional large water reticulation systems is considerably less than that required for equal lengths of PVC piping of the same duty. The iron piping also results in the production of less greenhouse gases.

REFERENCES 1. 4th International Conference 'PVC 90', Plastics & Rubber Inst., Brighton, UK, April 1990.

2. 'Reducing the Impact of the Greenhouse Effect' -A Submission by the Plastics Inst. of Aust Inc to the Parliament of the Commonwealth of Aust", Senate Standing Committee on Industry Science & Technology, Aug. 1989.

3. Boustead I. and Hancock G.F. 'Handbook of Industrial Energy Analysis', pub. Ellis Horwood, 1979.

P. B. JOLLY, G. W. PROWSE and D. N. CHIN Continued from page 37 exist. Extrapolation of this plot and the inclusion of historical and future estimated extraction data (see Figure 4), results in a simple tool which can be used to predict the long term performance of both the Mereenie Sandstone aquifer and production bores constructed in it. The nomograph has been constructed by superimposing two plots, borefield drawndown vs cumulative extraction from the Mereenie aquifer and years vs cumulative extraction from the Mereenie aquifer, onto the one graph. To CU MULATIVE EXTRACTION FROM MEREEN IE ( x 106 )m 3

' o,:.,o' --------'-' 20,:.,o'-----------"-' 30,:.,0'----------"' • o,:.,o' --------"' 'o,:.,o'--------", sofO2 0 0~o---'--'

_,,...-

_,,...- A···· : ········ ·· ···· ················

50

] z ;:

_,,,/

I

--.,.,,...----

,. ..................... .-<................... ..

g,oo r

, :.,, , .... , COEFF

200s

CONCLUSION A method has been developed to assist in determining the economically viable lifetime of the Roe Creek Barefield. It should be emphasised that the sustainable yield of this Barefield can be considered to be negligible for long term planning purposes. The life time of the Barefield is very dependent on demand management practices and re-use. Peak daily consumption currently approaches 2500 litres pet person and there is no effective re-use scheme (ie a scheme that uses water that would normally be supplied from the Barefield) in place.

REFERENCES

. (/)

~

CI 1 990 <C

OF CORREL WON O ' "

,.

w

~: L---~---~---~--~---~--~[: H ISTOR ICAL EXTRACTION DATA

PRED ICTED EXTRACTION BASED ON 2% GROWTH AND ALL INCREASE COM ING FROM MEREENIE

MON ITOR ING BORE 3600 (assumed pre pumping SWL 457.65m AHO)

Fig. 4 -

determine the water level of the borefiel1 at some future date go from that date on the vertical YEARS axis horizontally across to meet the predicted extraction curve (based on a predicted water consumption growth rate), then move vertically up or down to the borefield drawdown line (determined to be a linear relationship) and then horizontally across to the vertical DRAWDOWN axis.

Roe Creek borefield performance

FILTER SAND, GRAVEL & COAL TO AWWA B100/89 SINCE 1978 FOR PROMPT & EXPERT ATTENTION IN QLD, NSW, VIC, TAS, SA.

CA LF, G.E . - 1978; The Isotope Hydrology of the Mereenie Sandstone Aquifer, Alice Springs, NT, Australia. Journal of Hydrology, 381: 343 - 355.

JOLLY, P.B., PROWSE, G.W. AND CHIN, D.N. - 1990; The Amadeus Basin Mereenie Sandstone Aquifer - Regional Modelling based on the Diagenetic History of the Mereenie Sandstone. Water Resources Division , Power and Water Authority, NT. LAU, J.E. - 1989; Logging of Diamond Drill Core from Roe Creek Borefield, Alice Springs. Report for Water Resources Division, Power and Water Authority, NT. MABBUTT, J.A. - 1977; Desert Landforms, ANU Press, Canberra.

McDONALD, M.G. AND HARBAUGH, A.W. - 1984; A Modular Three Dimensional Finite Difference Groundwater Flow Model. Scientific Publications, Washington .

MACQUEEN, A .O. AND KNOTT, G.G. - 1982; Groundwater in the North Eastern Part of the Amadeus Basin. Water Division. Department of Transport and Works, NT. ROBERTS, K.P. - 1974; Analysis and Prediction of the Effects of Pumping from the Mereenie Sandstone Aquifer, Alice Springs. Water Resources Branch, Department of the NT. WELLS, A.T. FORMAN , D.J., RANFORD, L.C. AND COOK, P.J. - 1970; Geology of the Amadeus Basin, Central Australia, Australia, BMR, Geological Geophysicis, Bulletin 100.

ffi) !~!!!l...'!~~U~A~ Section Leader (Water Reticulation) $47,277 - $51,050 p.a.

RIVER SANDS Pty Ltd 683 Redland Bay Road, Carbrook, Qld, 4130 Ph (07) 287 6444 Fax (07) 287 6445

FOR SALE Portable Organic Vapour Analyser Model Century OVA 128 $9500 O.N.O.

Phone: 09 383 7510 Fax: 09 383 7509

Our West Ryde based Scientific Services Branch has undertaken scientific projects in environmental and analytical areas.

YOUR role will focus on programs associated with the complete water cycle. You will plan, organise, direct and control the activities of the section to provide the supply of quality scientific skills and the development of new ideas for the Board's management of the water reticulation system.

YOUR duties include • Co-ordinating field and laboratory work • Developing and managing research projects• Preparing reports and papers • Providing advice to management and other clients.

Essential: Degree or equivalent in a relevant discipline.

Inquiries

and

written

descriptions:

(02) 269 6484. Pos. No.: 3916.

The Board is a smoke-free workplace.

Closing date: 12 July, 1991. · Equality of Employment Opportunity is Board Policy THE NEW SOUTH WALES GOVERNMENT

Putting people first by managing better

WATER June 1991

41

TECHNICAL NOTES

WASTEWATER DISINFECTION

BY ULTRAVIOLET RADIATION

A WORKER FRIENDLY PERSONNEL SYSTEM

by TONY GARDNER, Ultraviolet Technology of Australasia Pty Ltd

by GLEN BOLNER, Personnel Services, WAWA

Ultraviolet Technology of Australasia Pty Ltd was the successful tenderer to install an ultraviolet disinfection system for the Townsville City Council at their Mt St John project, to disinfect treated wastewater at a maximum flowrate of 200 L/ s. The unit was commissioned in June and makes it not only the largest UV wastewater disinfection plant, but also the largest UV disinfection system in Australia.

One of the unique features about the installation is that there is only 100 mm of head available. Consequently the equipment had to be designed not to impede the flow through the system, involving a completely new design concept incorporating the channel into the UV system. The Low Pressure Mercuty Vapour lamps are arranged in three stages in series, and are controlled primarily by the flowrate of effluent, which is measured by a 450 mm Kent ¡electromagnetic flowmeter. At 200 L/ s all the stages would be radiating, and as the flow reduces, one or two stages shut down.

Each stage also has its own UV intensity meter measuring the transmission through the effluent stream. If there is high quality effluent as well as low flow, one stage can shut down.

A safety feature is that only disinfected effluent of an acceptable standard can pass through the unit. There is a shut down system that was designed by Gutteridge, Haskins and Davey, the hydraulically operated valve that would shut off the flow of effluent to the disinfection chamber if there was no power supply for that disinfection to take place. A 600 mm butterfly valve closes by city mains water pressure as soon as power fails, and automatically opens with the resumption of power and the starting up, once again, of the UV system.

All the water-wetted components are either 316L Stainless Steel or Teflon. Tube Plates are set into a concrete channel which is first epoxy-coated, and from tube plate to tube plate 85 mm Teflon Tubes are affixed with horizontal Mercuty Vapour Lamp support racks in between.

One of the critical factors with u/ v is the temperature of the mercuty vapour lamps. With the UVTA system the skin temperature of the mercury vapour lamp is not affected by the fluid temperature.

Thermostatically controlled fans increase or decrease the amount of air movement through the u/v chamber in order to maintain an equilibrium mercury vapour lamp skin temperature, which ensures maximum performance of the Lamp.

In the quartz sleeve mercury vapour lamp the air has no movement inside the sleeve. The water temperature will, in turn, affect the air temperature which surrounds the mercury vapour lamp within the quartz sleeve. A lowering of the skin temperature is a lowering of output, and it is possible to lose 20-40% efficiency with the quartz tube design system of yesteryear. The flow-through teflon tube design overcomes those traditional faults. The quartz sleeve also has to overcome the problem of fouling. As it is manufactured of quartz which is negatively charged, positive ions and organics are attracted to it. The fouling then retards the transmission of germicidal ultraviolet light out into the effluent. By flowing the effluent through teflon tubes with the mercury vapour lamp radiating and reflecting inwards into the effluent, the fouling problem is also overcome to a controllable degree.

Tubulent flow with the UVTA teflon tube system ensures better exposure to the ultraviolet radiation than a quartz system, and would therefore be the preferred design.

Changing of the lamps is accomplished with extreme ease.

Cleani~g of the inside of the teflon tube if and when required, can be earned out whilst the unit is still in operation. This is carried out with a high-pressure cleaner which is part of the equipment supplied.

This system, as a package unit, could economically and viably be constructed to accommodate up to 600 L/ s flow of treated effluent with 30 BOD/30 Suspended Solids.

Budget costing would be of the order of A$110 per litre per seond ~f disi_n~ection required, with a power consumption of 50 watts per litre d1smfected per second. All the UVTA systems, ranging from 100 L/s upwards are designed and manufactured _in Australia.

The Water Authority of Western Australia has installed an innovative computer system that cuts through traditional employeremployee barriers. HURMIS (Human Resources Management System) is designed in line with the Authority's philosophy of strongly encouraging employees' sense of job security within a participative management framework. All employees with mainframe access authority can call up their own files by using their personal code. They can instantly check on a whole range of data, from their current superannuation details through to leave entitlements and accruals. There is a two-way-benefit in all this: for employees it does away with any perceptions that information is withheld; for management it saves all the time and labour involved in answering inqueries."

HURMIS was developed by the Water Authority of Western Australia using the professional consulting services of the Computer Power Group. It was designed to overcome the enormous human resources logistical problems faced by one of the geographicallybiggest water authorities in the world. The Authority is regionalised and employs more than 4400 people who are spread at a huge diversity of worksites over an area larger than the European Economic Community. More than 657 000 customers in 300 towns and communities are provided with water supplies, sewerage, irrigation and drainage services.

In designing the system, the Authority provided project specificationa nd management, database support, analysis, programming, support and testing. Computer Power Group p~ovi~ed the majority of the technical resources and management with its TDSS (Technologies for the Delivery of Software and Services) constantly controlling quality.

The project employed a consultative approach and users were kept constantly aware of developments, resulting in on-time delivery and subsequent low maintenance requirements.

HURMIS comprises five basic data modules maintaining information on employees' personal records, leave entitlements training and development, accideift and workers' compensatio~ history, rehabilitation, and a module for system support and administration. _ Each of the modules contains a complex mix of information, eg: training and development handles every aspect of skills and experience acquisition and can be used by employees to help them in devising their own career development plans.

The Authority and Computer Power Group have now entered into a joint licensing agreement for CPG to market HURMIS, which is attracting interest across a wide range of public and private sector enterprises and further information can be obtained from David Clarke, Computer Power Group (09) 481 0488, or Graeme Brown - Manager Commercial Development, Water Authority of Western Australian (09) 420 2694.

42

WATER June 1991

1st National HAZARDOUS AND SOLID WASTE CONVENTION AND TRADE EXHIBITION Meeting the Waste Minimisation Challenge ...

Darling Harbour, Sydney March 29-April 1, 1992 CALL FOR PAPERS Abstracts by July 13 1991 Information: Hazardous Waste: Errol Samuel Solid Waste: Bert van den Broek Phone (02) 412 1388, Fax (02) 411 8634 Plus ...

OZWATER TRADE AND EQUIPMENT DISPLAY Information: Margaret Bates Phone (02) 413 1288, Fax (02) 413 1047

TECHNICAL NOTE

The Urraween Inground Reservoir Project

by ROSS ANDERSON, Hervey Bay City Council INTRODUCTION Until 1988 Hervey Bay maintained a fairly steady population growth rate which averaged about 5%. From 1988, connections to the water supply scheme have increased at a rate of over 10% per annum - which places a severe burden on the system. Visitors in holiday periods further add to the water demand . Demand management was introduced but had to be urgently supplemented by an accelerated and effective capital works programme. The Urraween Inground Reservoir Project is an innovative solution which provided immediate benefits.

PLANNING A Council planning report considered three sites and selected a quarry in Urraween Road as the most suitable since it was Council owned, beside the existing trunk mains, close to the centre of · demand and hydraulically and environmentally acceptable.

DESIGN Consulting Engineers were commissioned to carry out the design and documentation.

SITE WORKS Extensive reshaping of the site was necessary, together with removal of discarded quarry materials, site restoration and drainage.

Attention was paid to the finish of the internal surfaces to eliminate sharp projections that could potentially puncture the liner. The walls were finished with 50mm of crusher dust and the floors covered with 100mm of graded round river gravel. Under-floor seepage drains were installed and seepage from the walls also intercepted.

An inlet/outlet structure of concrete was constructed in the N.W. corner of the basin at floor level. The overflow is external to the reservoir, connected to the outlet pipe between the reservoir and the booster pumps. The overflow tower also houses the pump and level control probes. The whole site is surrounded by a manproof fence with security lighting.

LINER AND FWATING COVER Tenders were advertised for the Supply and Installation of Liner and Floating Cover.

The documentation called for the following: • geotextile underlay to protect membrane liner against puncture.

• a membrane liner fabricated from a completely waterproof material, resistant to puncture, and having a guaranteed service life of no less than 15 years.

• a floating cover fabricated from a puncture resistant material with a guaranteed service life of no less than 15 years. The cover also was required to be kept in position evenly across the tank when full, and to lay flat on the liner when empty.

• the contractor was required to have in place a Quality Assurance System.

• other matters including anchorage, maintenance and access were also specified.

THE MATERIALS The base, or support material chosen to underlay the liner, is BID IM U64. The liner and cover material chosen for the project is CARBOFOL, a modified polyethylene, manufactured in Germany. Carbofol exhibits the following characteristics: Physical Properties: high flexibility; high uni and multiaxial elongation; high resistance to stress cracking; simple welding system; reliable seam testing; low wave formation during installation; high UV resistance; compatible with bitumen.

Biological Properties: resistant to rodent attack; root resistant; resistant to microbe attack.

Chemical Properties: high chemical resistance.

Liner Material: 1.2mm CARBO FOL CHD. The material is black, quite flexible and easy to handle.

Cover Material: 2.0mm CARBOFOL LDPE with Single Coat.

The cover material is thicker and stiffer than the liner but still easily handled . The single coat is a light beige colour for heat reflection and blending with the environment. Deterioration of the coating due to weathering can be rectified by a fresh application; it therefore acts as a sacrificial surface to protect the underlying material. The material is supplied with a 15 year manufacturer's warranty.

LINER AND COVER FABRICATION The geotextile fabric underlay was unro ed over the prepared base, lapped, sewn, fixed to the perimeter beam and weighted with sand bags awaiting liner placement. Both the liner and cover was delivered in rolls 5.1 metres wide and 100 metres long, the necessary material being pulled from a suspended roll and cut to length.

Adjoining sheets were lapped 80mm for welding. All welding was carried out using self mobilised hot wedge welding units, with secondary welding using hot air and extrudate fusion welding methods. The welds contain two parallel weld zones with an open central core. The core is pumped with air to 2 bar pressure and held for a time to test the integrity of the welds. The roof contains a series of floats and weights to control its form as the reservoir fills, assist with drainage of stormwater and for keeping the roof structure in tension to prevent creasing. Both the liner and cover were securely bolted to a concrete perimeter beam. Vents were fitted to eliminate air from under the roof. To facilitate maintenance, an access manhole and portable airlock were provided. The drained reservoir can be inflated with low pressure air to keep the roof elevated.

Circulation of water in the reservoir was promoted by a tube about 700mm in diameter, made from the liner material, which extends across the floor to the opposite corner from the inlet/ outlet structure. Anchorage is at each end and centre.

COMMISSIONING AND OPERATION Commissioning entailed slowly filling the reservoir over a period of about 2 weeks. This could have been quicker if there had not bee such heavy demands on the system at the time. The only problem encountered during the filling was aif entrainment in the inlet tube; this was released by a diver puncturing the tube in several places.

There has been no recurrence of this. Some 4-5 weeks after the initial filling, failure of welds holdig the roof floats in place occurred. There was some expectation that this might happen due to the likelihood of insufficient heat being applied to the welds.

This has not created any operation problems and (at the time of writing) the contractor is arranging rectification. In operation, the reservoir has now taken the full effects of the peak summer demands and its performance has been excellent with no operational problems.

STATISTICS Volume: Top Length: Top Width: Bottom Length: Bottom Width: Depth: Side Slope Area of Lining Material: Area of Roofing Material: Number of Booster Pumps: Booster Pump Capacity:

36 megalitres 137 metres 65.8 metres 100 metres 28 metres 6.3 metres 1 in 3 10800 m 2 (allowing for waste) 10800 m 2 (Allowing for waste) 2 (provision for 3) 150 Lis each

CONCLUSIONS While membrane linings are used extensively in the mining industry and agriculture for open dams, their use as roofed reservoirs in town water supplies is an innovative approach in this country. The concept is also very cost effective, at a final cost of about $1.2 million for 36ML, it is thought to compare favourably with a 9ML concrete reservoir with similar pumps, pipework etc.

The project has created a lot of local interest and has been favourably received by the community.

WATER June 1991

43

1992 January 4-7 -

C...___C_O_i/1._'F._'ER_ffi_C._'E_CA_L_E._ND._!AR ___) AWWA CONFERENCES AND OZ WATER TRADE EXHIBITIONS 1992 March 29-31 - Sydney 1st National Hazardous and Solid Waste 1993 April 18-23 - Gold Coast 14th AWWA Federal Convention BRANCH CONFERENCES August 8-9 - N.T. Darwin September 7-8 - W.A., Rottnest September 13-15 - NSW, Wamberal October 11-12 - Vic., Marysville AUSTRALIA August 18-19 -

Cairns Mining and Mineral Processing/ Environment · August 25-30 - Hobart Local Government - Management of assets October 2-4 - Perth International Hydrology and Water Resources October 6- 7 - Perth Site Remediation Workshop October 9-11 - Adelaide Engineering Management November 27-28 - Perth Appropriate Waste Management Technologies November 29 - Perth Waste Treatment by Algae November 29-Dec 1 - Sydney Wetland Systems for Water .Pollution Control OVERSEAS August 4-19 - Taiwan, Keelung

5th International Cistern System Conference August 11-14 - USA North Carolina

Analaytical Compliance, Residuals August 12-15 - Sweden, Stockholm Water Resource in next century

August 14-16 -

New Zealand, Wairakei NZWSDA - For the P ublic Good August 26-30 - Czechoslovakia, Prague IAWPRC Large Wastewater Treatment Plants August 26-30 - Norway, Stavanger Northern Seas Environment September 3-5 - Scotland, Glasgow Health-related Water Microbiology September 8-11 - USA Atlanta AMWWA Distribution Systems September 24-26 - Spain, Costa Brava IAWPRC, Wastewater Reclamation & Reuse October 3-5 - Luxembourg EEC - Environment, Health October 6-10 - Canada, Toronto WPCF 64th Conference October 8-9 - France, Paris IWEM Groundwater Protection October 21-25 - Mexico, Mexico City IWRA Seminar on Efficient Water Use November 10-14 - USA Orlando, Fla AWWA, Water Quality Technology November 19-22 - Matta, Valetta Clean Seas November 20-22 - Portugal, Lisbon IAWPRC, Marine Disposal November 20-24 - China, Shanghai IAWPRC Asian Waterqual '91 November 21-24 - India, Bombay Afro-Asian Urban Water Management November 25-25 - Japan, Shiga IAWPRC Environmental Hazard Assessment November 26-27, Germany, Hamburg IWSA Inorganic Nitrogen Compounds December 1-4 - USA, Orlando Geographic Information Systems December 9-13 - Hong Kong Polmet 91 December 16-18 - Hong Kong Environmental Hydraulics

India, Nagpur Rural Water Supply and Sanitation January 15-16 - Hong Kong Aluminium in Drinking Water March 10-11 - Sweden, Jonkoping IWSA - Aesthetic Aspects April 15-17 - Italy, Venice Anaerobic Digestion of Solid Waste May 13-14 France, Lyon Geographical Information Systems May 24-30 - USA, Washington IAWPRC 16th Conference June 25-27 - Japan, Yokohama WPCF - Asia PacRim Conference September 1-3 - Switzerland, Geneva IAWPRC-IWSA - Filtration September 23-25 - Turkey, Istanbul Waste Management, Agro-Industries October 25 - Malaysia, Kuala Lumpur Water Malaysia 92

The association welcome details of conferences and exhibitions. Send all relevant details to: AWWA Secretariat, PO Box 388, Artarmon NSW 2064 Facsimile (02) 413 1047.

COURSES IGWMC and IHE Short Course in Applied Modelling of Groundwater Pollution 14-18 October 1991 Delft, The Netherlands Cost NLG 2600 Including class , notes and computer programs.

Information: J W Lyklema P.O. ,Box 6012 2600 JA Delft. NL.

u-e apologise ...

ELECTROCHEMICAL COAGULATIONFILTRATION PROCESS We apologise for an editing error in our April issue. In the above paper the incorrect diagrams were printed. Figure 3 refers to the laboratory test rig. Figure 5 is incorrect. The proper diagram of the overall electrochemical filtration process is printed below. It incorporates pH adjustment and preaeration to remove excess alkalinity, and post-treatment with coarse limestone to raise the pH.

BACK\rlASH

CONTROL f!LTER

' - - - - " " - - EffLUCNT

DVERF"LO\I

AIR

AIR

PRETREATMENT

COAGULATION F"ILTRATION

FINAL

INDEX TO ADVERTISERS Ae rat ion & Alli ed Tech nology Pty Ltd .. ... .. ........ ............. 39 Ap pli ed Hydro Tec hnol ogy Pty Ltd ............. .......... .......... 41 Calgon Carbon Co rporat io n .. ... .. ......... ... ........................... . 7 Jam es Cummi ng & Sons Pty Ltd ... ........................ .. .. ... .. 35 Flygt ....... .... .... .......... ......... ........... .............. ... .. ...... .. ......... . IBC Jacmor Engin ee rin g Pty Ltd .. .... ... .... .... ... ..... ... ... ....... ..... ... 2 Larox Pty Ltd ............ .. ......... ... ....... ........ ............ .. ......... .. ... 39 Me lbou rn e Informati on Tec hn o logy Services .......... ...... 21 Merck ......... ... ........ ....................... ........ .. ..... ................. ...... . 11 Process & Po llu t ion Contro l ..... ................... .................... 13 Punc hbowl Pipes Pty Ltd .. ..... .. .. .......... .................. ........ .. 13 River Sands Pty Ltd .... ... ..... .... .... ................. ..................... 41 Saun ders Valves Australi a Pty Ltd .................. ....... ...... ... 29 Simm onds & Bristow Pty Ltd ... ... .... .................... .. ..... .. ... 13 Tube m akers of Australi a Lim ited .. :...... .. ........ .. ....... .... OBC Ultraviolet Tec hnolo gy of Aust ralas ia Pty Ltd .. .. .... .. .. . IFC Vini dex Tube makers Pt y Ltd .......................... .... .............. 25 Wate r Board .......................... .. ............. .. ...................... .. .... 41

POSTREATMENT

PROCESS Artwork : Johnzar t. Telefa x 03 398 2834

44

WATER June 1991

Printed by Globe Press. Brunswic k