Water Journal June 1982 by australianwater

1ss N 0310 - 0357

Official Journal of the

" W~ii;M Mt;1~1\!Mi3;E~I•) W$-ii :f;tMi =I ;141-i--i•XeJr-ii t•)~ • Reg;s te,ed by Aus t,at;a Po s t -

pubt;c at;on no. VBP 1394

Vol. 9, No. 2, June 1982-$2.00

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EDITORIAL

Chairman, F. R. Bishop E. A. Swinton Mary Drikas Dr. Wayne Drew P. McKenzie J. H. Greer C. Tucak R. McGrath J. E. Dymke D. Hammerton R. Camm A.Payne J.Paul Dr Barb. Bowles K. Hartley Editor: Publisher: G. R. Goffin A.W.W.A.

Official Journal of the AUSTRALIAN WATER AND WASTE WATER ASSOCIATION

Vol. 9, No. 2 June 1982

BRANCH CORRESPONDENTS

CANBERRA A.C.T. J.E. Dymke 4 Story St., Curtin 2605 Office 062-89-1777 NEW SOUTH WALES P. McKenzie, Prine. Eng. Water Supply, P.W.D., State Office Block, Phillip St., Sydney 2000. 02-270-4561 VICTORIA E. A. (Bob) Swinton, C.S.I.R.O., P.O. Box 310, South Melbourne 3205. 03-699-6711 QUEENSLAND K. Hartley, Gutteridge Haskins and Davey, G.P.O. Box 668, Brisbane 4001. 07-221-7955 SOUTH AUSTRALIA Mrs. M. Drikas, State Water Laboratories E. & W. S. Private Mail Bag Salisbury 5108. 08-258-1066

CONTENTS Viewpoint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Association News, Views and Comment . . . . . . . . . . . . . . . . .

I.A. W.P.R. News . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Protective Coatings for Waterworks Structures. Some Experiences of the S.R.&W.S.C. - L.A. Reilly and T. J. Richards . . . . . . . . . . . . . . . . . . . .

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

Melbourne Water Distribution System Corrosion and its Mitigation . . . . . . . . . . . . . . . . . . . . . . .

Book Reviews

WESTERN AUSTRALIA C. M. Tucak, 18 Ventor Ave., W. Perth 6005 09-321-2421 TASMANIA G. Nolan, 20 Browne St., W. Hobart. 002-28-0234 NORTHERN TERRITORY J. Paul, Water Div. Dept. of Transport & Works, P.O. Box 2520, Darwin 5794. 089 89 6077 EDITORIAL & SUBSCRIPTION CORRESPONDENCE G. R. Goffin, 7 Mossman Dr., Eaglemont 3084, 03:459-4346 ADVERTISING Miss Ann Sykes,, Appita, 191 Royal Pde., Parkville 3052. 03-347-2377 WATER

COVER Inlet works at an early stage of filling of the Winneke Reservoir, the newest water storage in Melbourne's water supply system which is operated by the Melbourne and Metropolitan Board of Works. The reservoir, which has a storage capacity of 95,000 megalitres, holds water pumped from the Yarra River near Christmas Hills, through a 1.2 kilometre long pressure tunnel. After its release from the reservoir, the water is pumped to a treatment plant as it is drawn from parts of the Yarra catchment which include populated areas and farms . Previously, all of Melbourne's water was drawn from closed catchments.

The statements made or opinions expressed in 'Water' do not necessarily reflect the views of the Australian Water and Wastewater Association, its Council or committees.

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WATER

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WATER

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WATER

AUSTRALIAN WATER AND Âˇ WASTE WATER ASSOCIATION

FEDERAL PRESIDENT D. J. Lane, State Water Laboratories , E. & W.S. Depa rtment , Private Mail Bag , Salisbury, 5108

FEDERAL SECRETARY F. J. Carter, Box A232 P O Sydney South , 2001.

FEDERAL TREASURER J. H. Gree r, Cl- M.M.BW. 625 Lt. Collins St., Melbou rn e, 3000.

BRANCH SECRETARIES Canberra , A.C.T. J.E . Dymke, 4 Story St .,. Curtin, 2605. Office 062 (8 1 9385)

New South Wales D. Ru ssel l, Camp Scott & Fu rphy, 781 Pac ific Highway, Cha tswood 2067. (02-412-2688)

Victori a J. Park, S.RW .S .C. Opera tor Train ing Cent re, P.O. Box 409, Werribee, 3030. (74 1-5844)

Queensland K. Stri ckl and , C. I. G. Ltd. , PO Box 40 , Rocklea 4106 . (07 275 01 11 )

South Au stralia A. Glatz, State Water Laboratories, E. & W.S. Private Mail Bag , Sa lisbury , 5108. (258-1066)

Weste rn Australia R. Loo, 455 Beach Rd . Carine. (09-447-6550)

Tasmania P E. Spratt, England , Newton, Spra tt & Murphy, 132 Davey St., Hobart , 7000. (23-7591)

Northern Territory J. Kenworthy, G. H. & D. P O Box 35 1, Darwi n 5794. (089-8 1-5922) WATER

VIEWPOINT WATER RESEARCH Water research in Australia, or rather, the unco-ordinated approach to it , has appeared as a recurring theme in publi c debate during the last two decades. Given Australia's harsh environment , limited water reso urces and the importance of water to social and economic development , this is perhaps understandable. Recently, Mr R. Jacobi's private members bill for an institute of freshwater studies has further stimulated debate, and highlighted Australia's uniqueness among developed countries in not having a national water research centre, ie a nation al focus. At the same time , two very comprehensive reviews of water research have been underway in Australi a; one by CS IRO of its water resources research activities to identify priority areas for future research; the other by a working gro up of the Australia n Water Resources Council. Th is 'is one member' s version of the view point of the A WRC's "gang of seven" - Messrs R. F. Bange, S. E. Flint, R. J. Millington, K. J . Shepherd, L. B. Devin, J . N. Mann, and W. D. Williams. There is growing evidence that the quality of Australia's limited water resources is beii;'g impaired by man-induced cha nges to catchments and stream regimes, and by contamination of the aquatic environment through th e application of agricultural and industrial chemicals. This, coupled with a changing social, economic and demographic scene, is resulting in greater emphasis being placed on water quality and the maintenance of existing assets, rather than the development of new works. These changes are posing substantial and complex problems for the water industry, the resolution of which will require a better understanding of water issues a nd aquatic ecology. Research is the key . Against this backgro und major deficiencies can be identified in the current national water research effort. There are signifi cant gaps with regard to ecological, limnological, hydrological and economic issues. As well , the research effort is not balanced. There is too little effort on applied and developmental research; too little by tertiary educational institutions and State water agencies; too little continuity; and too little concentration of research effort. In short, Australia's water research effort is inad eqaute, fragmented a nd poorly bala nced , and has substantial gaps . This has resu lted from inadeq uate funding, poor institutional arrangements, lack of researchers and poor overall management. The current level of funding compared to the effort needed to overcome identified gaps is therefore clearly inadequate. The most recent comprehensive survey of water research in Australia, the 1979 'A WRC Inventory of Water Resources Research', reveals a total annual expenditure of $12 million . Partial.statistics suggests that the level of research fu~ding has since declined in real terms. International comparison based on water research expenditure as a proportion of Gross Domestic Product and as a percentage of capital investment in the water industry, indicates that a n ex penditure of $30 million would be justified. f

Water research in Australia is undertaken by a very large number of organisations . Further, in CS IRO , our principal water research organisation, water-related research is dispersed through more than twenty divisions and units. Consequently, arguments for a single research centre appear persuasive. Close examination, however, of the research arrangements in countries with single water research centres suggests no model completely satisfactory to Australia. A further consideration is the considerable time and expenditure required to create a new institution . A t this stage, the development of a single water research centre is inappropriate; the most cost-effective approach would be to build onto existing research centres by providing increased continuity of funding and by developing larger groups or centres of concentration . Tertiary educational institutions and State water agencies are particula rly suita ble for such development as they already have well developed administrative infrastructure. Given the dispersed nature of water research in Australia, the current arrangements for assessment of national needs and priorities, co-ordination of research effort, and the dissemi nation of results, are inadequate. Of the many approaches possible, the most satisfactory, would be a national water research council reporting to the Minister for National Development and Energy, and comprised of an appropriate mix of user, management and research experience. Complementary arrangements would be required to ensure better coordination of the Commonwealth water research effort. In summary, the greatest need in water research is for an authoritative group to ensure that water research and its associated administrative ar;angements are responsive to the changing demands of the industry. A national water research council , adequ ately supported and funded, is seen as central to achieving this. L.B. DEVIN Assistant Secretary, Water Branch Department of National Development and Energy 7

ASSOC/A TION NEWS VIEWS AND COMMENTS PRESIDENT'S MESSAGE Federa l Council met in Sydney on 14th May, 1982 , fo ll owing a meeting of the Executive Committee o n 13th May. Th e fo ll owing matters were di scussed .

Rules A final draft of the Rules .has been prepared and a plebiscite will now be held for their acceptance by members . Counci l rejected a suggesti on tha t an additional class of member 'Fell ow' be esta blished. The revision of th e Rules has been a long a nd tedious task. Henry McFie and Don Walters (Tasmania) are to be congrat ulated on t heir sterling effort.

21st Annual Report Counci l considered a fina l ' mock-up ' of the proposed 2 1st Annual Report of the Association. This wi ll now be printed and is expected to be availab le later this year. The Report will be used as a general promotional brochure particu lar ly for th e forthcoming Federal Convention in Sydney a nd the Specialist Conference in Darwin, both in 1983.

Subscriptions Subscriptions for 1982/ 83 will be unchanged, they remain at $20 p.a . for Members and Associates and $5 for Students.

Conferences P lanning for the 1983 Sydney Co nvention is now well advanced and the N.S.W . Organising Committee is to be cong ratu lated on progress to date, part icu larly in view of the extraordi na ry number of personnel changes within the comm itt ee due to sickness and transfers and if the Northern Territory maintain the standard set by their outstanding fir st Brochure we can look forward to an excellent conference in Darwin in September 1983. ÂˇMembers are urged to publicise bot h of these meetings at every opportunity in order Âˇ to ensure good attenda nces.

Relationship with Institute of Engin eers, Australia Discuss io ns have tak en place between senior officers of th is Associat ion at both the Federa l and State levels and Officers of the I. E. Aust. in order to strengt hen ties between the two organisations. To this end the Federal Vice President Frank Bishop recent ly attended a meeting of the Co llege of C ivil Engineers, of the In st itu tion, and Dr I. Mair,

C hai rm a n, Co ll ege of Civil Engin eers attended A WW A's rece nt Council Meeting. The discussion at that Counci l Meeting promoted a greate r understand in g of the difficulties fac ing the two organisations in prov iding appropriate services to members hav in g regard to rapid technologica l de ve lopment s a nd provid ed a basis for the further deve lop ment of li aisons at the Federal and State leve ls .

LIFE MEMBERSHIP AWARDS At the Federal Council Meeting on May 14th Honorary Life Membership was awarded to two Members of the Association.

Water and Wastewater Resea rch in Austra lia The Standing Comm ittee on Science & Tech no logy has produced a Sc hed ule of Wat er and Wastewater Researc h being undertaken by major wate r and se werage authorities throughout Au stralia. Origina ll y planned to be published as an in sert to the Journa l 'Water', difficulties were exper ienced in obtaining inform atio n, a nd the document is not as co mprehen sive as intended. It is st ill a very use fu l co mpilation a nd cop ies of the report wi ll be made ava ilab le to Branches, to participating Authorities and to the Australian Water Resources Council a nd the Water Research Foundation. Cop ies a re availab le from the Federal Secretary at $6 per copy.

Life Me mbersh ip Upon recommendation from W .A. and N.S.W. Branches, the Council conferred Honorary Life Membership upon Don Montgomery a nd Peter Hu ghes as reported later in the New s.

DON MONTGOMERY -

W.A.

Don , a P ast Federal Pres ident a nd Co uncill or for ma ny years has given tremendou s service to t he Association both at Branch and Federal levels and he was C hairman of th e Organising Committee of the highly successfu l Perth Convention . 'Don now enters a well earned retirement.

DOUG LANE Federal President

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'THE GUY PARKER' ANNUAL AWARD At the Federal Counci l Meeting o n May 14th it was reso lved that the co ntribution of Guy Parker to the Associat io n shou ld be recogni sed by presenting an annual award entitled ' Th e Guy Parker Award' for the best paper published each year in the journal ' Water'. Papers for the first award will be those pu bli shed in the period June 1982 to March 1983. The award wi ll co nsist of book s to the va lu e of $200 and selection of the winning paper will be by a panel of five members nominated by the C hairman of the Editorial Committee and to include a member of the Sc ience a nd Techno logy Co mmittee and th e Editor of the J o urn a l.

PETER HUGHES -

N.S.W.

Peter, Engineer-in-Chief of the M .W.S.& D. Board, Sydney, stepped out of the demand ing post of Federal Secretary last year after guiding the Association through five difficult years. H e was largely the architect of the present system of Standi ng Committees with its contribution to decentrali sat ion and dec ision makin g. Peter has also been awarded the Association's Service Plaque. WATER

ASSOC/A TION 10TH FEDERAL CONVENTION Sydney - April '83 A progress repo rt has been prov ided by Or ga ni sin g Co mmitt ee C ha irm a n Tim Smyth . On e hundred a nd thirt y-eig ht pa per Syno pses have bee n received fro m whi ch some 65 will be selected by th e P rogra mm e Sub-commi ttee to main ta in a full ' t wostream ' pa per present at io n. O f th e Syno pses, 22 per ce nt were fro m Uni ve rsities a nd research o rga ni sa ti o ns, 28 per ce nt fr o m A uth o riti es a nd age ncies, 15 pe r cem fro m ma nu fac tu re rs, 20 per cent fro m consul ta nts a nd 15 per cent fro m ove rseas including U .S.A., U. K. , Canada, Fra nce, J a pa n, N.Z., Egy pt a nd Th ail a nd. To pi cs ra nge o ver the full spectrum o f th e wa ter a nd was tewa ter fi eld s. Coverage a nticipated will include leve ls a nd enh a ncement of d rinking wa ter q ua li ty a nd t he clea nsing of treated efflu ent , by aquacul ture systems examin ed fro m va ri o us viewpoint s . In additi o n to the tec hni ca l progra mm e acti viti es will includ e: a major equipment exhibition , tec hni cal to urs , a post-co nve ntion to ur o f coa l/ power centres in th e Hunter Vall ey, a wid e rangin g progra mm e of social event s. The First Not ice of the Co nventi o n is j ust a bout to iss ue .

'WATER' - CONTENT VICTORIAN BIAS? So me co mm ent has bee n received fro m crit ica l reade rs of Water - a nd there are so me (fo rtun ately) - a ll eging predo min a ntl y Victori a n co nt ent in o ur tec hni ca l pa pers. th e all ega ti o n is qui te co rrec t - witn ess th e fo ll ow in g in vent o ry o f paper so urces in the nin e iss ues to June . 2 O verseas Victoria 18 N.S .W. 6 Qu ee nsla nd T as . S. Aust. 4 W . Au st. 2 N . T errito ry ni l A .C. T . 2 Bias? - no t a bit of it - just pl ain lac k o f a ny acceptab le alt ern at ives . It 's true th a t th e Edito ri a l Co mmittee is based in Melbo urne a nd na turall y it s sph ere of influ ence is prim a ril y Vi cto ri a n. Th e Co mmitt ee ' s respon sibilit y incl ud es ensuring sa ti sfacto ry techni ca l cont ent a nd its earn est des ire is that th e co nt ent refl ects th e na ti o na l nature o f th e Assoc ia ti o n . Effo rt s to thi s end a re defeated - not by a ny bias but by th e scarcit y o r co mplete lac k o f accepta ble pa pers fr o m oth er Sta tes . Th ere is nothin g th e Committee wo uld enjoy more th a n a delu ge o f pa pers tha t wo uld reli eve it fro m co nsta nt dema nd o n loca l (Vi ctori a n) reso urces. Pape rs result fro m energy, a ppli cati o n, interest a nd pro mot io n . Members , Branch Committees, C orrespondents and Counci llors - it' s up to you . WATER

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NEWS

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VIEWS

QUEENSLAND BR ANC H A CTIVITIES

At a dinn er meeting held on 28t h April , C hri s Kidd of Au stra li a n G roundwater Co nsulta nt s spok e o n " H ydrogeologica l Con sidera ti o ns for Land Disposal of Ha zardou s Was tes" . This was ex tremely to pi cal beca use of co ncurrent medi a interest in ma nagement of Brisba ne City Co un cil 's waste di sposal site a t Will awong a nd of th e in creas ing publi c co ncern with the subject , no t onl y in Brisba ne but in all urba n a reas . OP ERATOR TRAINI NG Th ere a re some 190 sewage trea tm ent p la n ts o perate d b y loca l gove rnm e nt a uthorities in Qu eensla nd, hence o pera to r tra ining is a n impo rt a nt iss ue. Some yea rs ago th e Qu ee nsla nd Branch o f A .W.W .A . was in st rum enta l in ini tia ting co urses for o pera to rs o f water, sw imming poo l a nd sewage t reat ment pl a nt s. Th e courses a re run by correspo ndence, supplemented by a n intensive pe ri od o f practi cal work in Brisba ne by th e Tec hni ca l Corres pondence Schoo l o f th e Qu eensla nd Edu cati o n Depa rtm ent. Ce rtifi ca tes a re awa rded by A . W . W .A. to o pera tor s success full y co mpl eting th ese co urses. Two awa rd night s a re held in the mi ddle of eac h yea r as ad vised in th e progra m be low. The Qu eensla nd Branch Committee is currentl y co nsid erin g the possibilit y o f supplem entin g the prese nt ce rtificate sc heme by th e int rodu ctio n of a n additional certifi cate of co mpetence to be awa rded to opera to rs wit h the necessa ry experience. COMI NG EVE NTS

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June 30th : Presentation of Operato rs' Ce rtifi cates . Rod Lehma nn of Sinclair Kni ght a nd Partners will spea k o n 'Inflow Infiltration Studies of Sewerage Reticulation S)•stem s'. • Jul y 14th : Presenta tio n o f Opera to rs' Ce rtificates . Ross Sadler a nd Brian Ri gden speaking on 'Biodisc Treatment of Sugar Mill Waste '. • A ugust 11th : Annu a l General Meeting. Fred Greenha lgh , la te of Brisban e City Co uncil , wi ll remin isce o n th e sewerin g o f Brisba ne. • Au gust 27th : On e da y se min a r on 'Water Quality Aspects of Residentia l Waterway Development'. See th e noti ce on page 20 . • O cto ber 20th: V. E . Schmidt on 'Experiences in Papua ew Guinea in Organizing Water and Wastewater Treatment'. • No vember 17th : Spea ker to be arra nged.

SOUTH AUSTRALIA

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COMMEJ\JT

jec t 'Odour Control at Sewage Treatment Works' . The interest in th e subj ect was highli ghted by t he fact tha t 55 members and fri end s a ttend ed th e meetin g. After genera l di scuss io n o n th e ca uses o f odo ur a nd fe atures o f sewe rage systems , Mr Corn ell o utlined a poss ibl e mean s of redu cin g th ese odo urs a t the source by co ntrollin g th e wastes ent ering the sewerage a nd mainta inin g un favo ura ble condi tio ns fo r odour form ati o n, e.g. aerobic conditi ons, sewer length s a nd sewage ve locit y . Meth ods for odour control a t sewage treatm ent work s were described including plant des ign f tures , odour mas king, chemi ca l o xid a tion , biological oxid a ti o n , adso rpti o n a nd wet sc rubbing. Mr Cornell also discussed sewage treatm ent processes a nd examples of eac h process a nd meth ods o f d ispos ing of solid s . Th e talk was well illustrat ed by slid es. On Friday 11th June (as we go to press) the Bra nch will be addressed by Mr M. D. Burch o n th e subj ect 'Limnology of the Antarctic Lakes'. Mr Burch is a Biologist a t the Sta te Wa ter Laboratories, E.&W .S. Depa rtment but previo usly was employed as a Bio logist by th e Anta rcti c Division, Departm ent o f Sc ience and Technology from 1977-81. During this tim e he was invol ved in two Austra li a n Na ti o nal Antarc tic Research Expediti o ns a nd hi s talk will relat e to hi s experiences bo th li ving a nd working as a Biologist in th e Anta rcti c. SEMINAR 'Disinfection of Water Supplies'

Friday Jul y 23rd (a mended date) a t I.E . Au st. , 11 Bagot Street, Nt h . Adelaide, 3.30-9.30 p .m. The seminar will be opened by Hon. Jennifer Adam son, Mini ster of Health. A 10 speaker panel wi ll include two from intersta te and di scuss.on will embrace three sessio ns Current Practice: Scientific a spec ts. Production o f ch lorin e. Ne w developm e nt in chlorine produ ction. Technology & Effectiveness: Technology of chlorinati o n. Effectiveness of chlorination (bacteria , viru ses, amoeba) . Side Effects & Alternatives: H ydraulic benefit s. Corrosion. T rihalometh a nes, tas te a nd odour. Alternat ives. Brochures a re ava ila ble a nd enquiries should be directed to the Convenor , Dr J . M. Roll s (08-258 I 066) or to Branch Secreta ries . S. A . Bra nch meetings have been held on Friday night s since 1962. Foll o win g receipt of co mm ents a bo ut meeting times a telepho ne survey canvassed th e o pinion of 53 per cent o f th e membership. By substantial majoriti es , th e members contac ted fa voured ex isting meeting a rra ngements - Frid ays (67 per cent) 5.45 p.m . (84 per cent).

BRA NCH ACTIVITI ES

Th e seco nd mee tin g for t he yea r was held o n Frid ay 30th April a nd Mr M . A. Corn ell of Ca ld we ll Co nnell Engineers Pt y Ltd, Melbo urne, ad dressed the Bra nch on th e sub -

STATE N EWS

In 1975 th e State Government commiss ion ed th e Ri ver Torrens Stud y to co -ordin a te a plan of acti o n for th e deve lopment and

ASSOC/A TION management of the river. The study recommended that the river be developed as a 'Linear Park ' linking the coast to the foothills, providing a valuab le recreation area for the people of South Austra li a comprising natural and recreated ' natura l' areas and parks. A Flood Mitigation Study was also undertaken to invest igate the nature and risks of the flooding prob lem and a sc heme to mitigate flood s up to a 200 year return period was proposed. Work on thi s ambitious project consisti ng of a park ru nning a ll the way from the hill s to the sea commenced on January 4th 1982. The total cost of the project, the centrepiece of the State's 150th birthday celebrations is $24 million .

NEW SOUTH WALES BRANCH ACTIVITIES

The major item to report since the last issue was the very success ful Regional Conference at Nowra on March 12- 14. Some 100 member s and g u ests attended, the Shoalh aven City Co uncil co-operated whole heartedly and made avai lable its new C ivic Administration Centre and the Mayor, Alderman G. H . Watson opened the Conference.

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NEWS

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VIEWS

Department described the investigat ions carried out for augmenting the head works of the Cit y of Shoalhaven's water su pply system a nd gave details of the river intake, offstream storage dam a nd 60 ML/ d water treatment at present under co nstruction. Noel Southwell of Shoalhaven City Council continued with details of planning studies for water distribution and descr ibed the present state of construction of the adopted works. The total of headwork s and distribution works is about $40 million . The M.W.S.&D. Board contribu ted with a ta lk by John Bellamy on the Shoalhaven Scheme - the staged scheme for augmenting Sydney's water supply with pumped transfers from the Shoalh aven River. Onto the Sewerage Theme, Ron Hemmings, H.D.W.B. and Ray Anderson summari sed a 12 month s joint tri al between the Hunter Water Board and C.l.G. of in-main oxygen treatment of sewage and exa mined potential uses for this system. Bob Gibbs of the Public Works Department gave a clear analys is of effluent disposal alternatives available for tow n sewerage schemes and spoke of the difficulti es being experienced obtain ing comm unity acceptance of major coastal outfall s. Combining water and sewerage, albeit on a smaller scale, Commander B. L. Swan spoke about advances in water and waste water

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COMMf,NT

member s at tended th e Water Board Theatrette on Apri l 20th to hear Trevor Judell spea k on 'Base Line Studies and Continuous Monitoring for a Shallow Tropical Bay Receiving Nickel Refinery Effl uent' . T he paper, initiall y presented at the recent IA WPR Con fe rence in So uth Africa, described the approach to and results of some eight years of baseline studies and subsequent monitorin g of coastal waters adjacent the Greenvale Nickel project's processing plant effluent di scharge point in Halifax Bay, Queensland. This most impressive programme invo lved measurements of ph ysical, chemical, biological and micro-biological characterist ics of the seawater and substraits. The studies showed that the receiving waters, initiall y nitrogen deficient, have been loca lly enriched in ammoni um-nitrogen but no adverse effects on the ma rine eco logy have been det ected. The paper questioned the applicability of the current means of assessing effects of effluent di sc harge and called for wider dissemination of data and conclusions of similar studies. Dr Jude!! also gave some commen ts on the highly success ful IA WPR Conference in South Africa. Future programmin g includes: • A soc ial function on May 28th (as we go to press) which will be an Indones ian Night. • Techni cal sessions by Professor Prince on the Hawkesbury River Problems and R. Dixon on Diaphragm Walls and Caissons - dates and details to be announced. NEWCASTLE SUB-BRANCH

A moment of relaxation at the Nowra Conference.

The Theme 'Coastal Development - Opportunities and Problems' gave fu ll scope for a maximum of local interest papers and discussions with the range very much extend ed by the Nava l contribution. Opening the technical sessions, John Durrant, the City Engineer, spoke frankl y on th e problems fac ing a rapidly grow ing regional au thority. In particular , he described the frustrat ions hi s Council experiences in obtain ing necessary approvals from a multitude of Government agencies for any major development. Commencing the water theme Barry Antell and Mike Partlin of the Public Works

facilities in naval ships and installations and of increasing international concern about discharges from ships at sea. At the Conference Dinner, Commodore T. A. Dadswell , Commanding Officer, R.A.N. Air Station Nowra was the guest speaker and gave an insight into the navy today and some background into the decision to buy the In -

vincible. The Sunday was devoted to inspections of the offstream dams and water treatment plant under construction near Nowra and the very enjoyab le Conference closed with a barbeque lunch at Shoa lhaven Heads Beach . A di sappointingly small audience of 18

Kevin Young , Hon. Secretary adv ises the followin g details: • At a ge neral m~eting on April 19th, Mr G. Taylor of Tomago Aluminium talked to the Branch on 'Water Pollution and Aluminium Smelters'. • As we go to press, on May 24th , Mr W. Johnson of the Hunter District Water Board will be covering the exotic area of 'Water and Wastewater Practices in Japan'. • The 21st of June will bring the Bra nch back to the loca l scene with a talk on 'G roundwater Resources of Coastal Sandbeds in the Lower Hunter'.

WESTERN AUSTRALIA BRANCH NEWS

'Water' is indebted lo the Branch Secretary fo r the fo llowing comment and assistance: The W .A. Branch is in serious trouble with the Ed itor, it is repeatedly neglecting to advise the Ed itor of happenings and authors appear to be non-existent in the West. Perhaps it is lack of education, perhaps their heads have ou tgrown the 'b ig' state. Th ey love to co mpare the West's progress to other states and 'use' the mista kes of the WATER

ASSOC/A TION east to learn - yet appear uninterested in all owing the rest of Au strali a to 'use' the West's acquired knowledge. Perhaps th e construction of a 'w ide ' canal from Joseph Bonaparte Gulf to Eucla would merel y confirm the east' s suspicions that 'Waisted Worters' - the nam e of the local newsletter, really stood for: We in the Wes t Always In sist on Seeing Th e East's Development o nl y to say: What Orrible Rubbi sh The East's enginee rs Regularly Succumb to. Surely there must be someone in the West capable of reading and writing! Obviously the West has prob lems - shared by the West's Secretary, howeve r, the wheels of th e press mu st contin ue to roll so th e fo llowing comments have been provided (belatedl y) to the harassed Editor. • The West now has a progra mme subcommittee - wh y it has taken IO years we wi ll never know. • A very successful comb ined meeting was held with the Wate r Resources and Environmental Branches of the Institution of Engineers W .A. to hear Bob Wark 'The Fastest Tongue in th e West', present a very well prepared paper on 'Harding Dam Project - Environmental Review and Management Programme'. Hi s co-aut hors , R. Harvey (P.W .D.) and Keith Lindbeck (Dam es & Moore), ably supported the presentation. It was a 'fu ll hou se' attendance and suggested similar arrangements for future meetings. • Wou ld you believe a week later another good a udience turned out to jeer the speakers from the Govt. Chemical Laboratories, Noel P latte!, Phil Jack and Ty Webb when they pub li cly tried to deny that 30 m 3 of 'cleanyellowsand' was the best and latest recommended 'Swimming Pool Water Treatment' for private pools - an extremely interesting presentation - though one sceptic was not convinced . By the time this issue hits the streets, the 22nd June meeting would also have concluded. This meeting is about a controversial local issue "The Peel Inlet Problem". This large expanse of water is experiencing annual algal blooms with the W.A. Government being under increasing pressure to find solutions to the problem. The department of Conservation & Environment has done a lot of detailed work on the cause of the problem but as a lways the solutions are neither easy nor cheap. WAT ER

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NEWS

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VIEWS

The W .A . Branch committee felt the A .W .W .A., with its diverse and ex perienced membership shou ld take an int erest in the Peel Inlet problems and this talk will be specifi ca ll y aimed at the alternati ve solutions which have bee n or a re rece iving consideration including, e .g.: • Precipitation of phosphorus a nd/ or other nutrient s. • Soil fix ation of nutrients. • River diversion and dredgi ng alternatives. • Amendments to farming tec hniques. W.A. Members wi ll be given a n opportunity for a site visit during the nex t 'bloom'. STATE NEWS

Last month, the University of W .A. gained a Research Centre of Excellence when a team led by Professor Jorg lmberger was the recipient of a $1.6 million Federal Government research grant to set up a Centre for E nvironment Fluid Mechanics. The foundation s for the Centre were laid by work over the last two years of a team under Professor lmberger on fluid mixing in the Wellington Reservoir which has already had most significant beneficial results. The new Centre will continue to work in the fluid mixing area which is of great importance to many aspects of water quality improvement and it will have close ties with the Centre for Water Research, funded by the State Government and the University .

NORTHERN TERRITORY BRANCH NEWS

Bra nch attention has continued to focu s on the September 1983 Conference during the past three month s with a consequent lack of general activit ies. The initial call for papers has generated considerab le interest a nd th ere has been a surprisingl y large number of enquiries from potential participan ts already. Normal bran ch activities have resumed and there will be an increased concentrati on on these over the next three month s. TERRITORY NEWS Darwin

Construction of the first stage of the 1350 NB MSCL water pipeline from Darwin River Dam to McMinns Pump Station has commenced. It involves 20 .5 km of pipeline costing $3.5 million and is due for completion in September 1983. The Contract was awarded to John Holland Constructions. This project is part of the ongoing upgrading of Darwin 's water supply required by the contin ued popu lation expansion. Extensive investigations of the ground water usage in the surrounding rural areas are being undertaken by the Departm~nt of Transport and Works arising from the identification of locali sed pollution in some bores. Rural subdivisions have been extremely popular in recen t years and there has been

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COMMENT

no control over the use or construction of bores. New subdivi sions with blocks of 2 hectares and less are required to be provided with reticulated town wa ter until such time as clear guidelin es and policies for the use of ground water are estab lished . Katherine

The new Water Treatment Plant is nearing comp letion and will be commissioned soon . Katherine has suffered from a hard water suppl y for man y years and the advent of 'soft' water will be greatl y appreciated by the community.

VICTORIA BRANCH ACTIVITIES 'Industrial Waste Disposal in South East Asia' was the theme for the address delivered by Steve Hollis of Scott and Furphy Engineers, Canberra and Denis McLean of Camp Scott Furphy, Melbourn e at the March meeting. The speakers outlined the pollution problems generally fac ing ASEAN countries currently undergoing rapid phases of indu stri a l d eve lopment wit h parti c ular refere nce to Malaysia where the Scott and Furphy Consu lting Group have recently completed a major stud y on behalf of the Malaysian Government to prepare ' Poli cy Guidelines for the Collection, T reatment and Disposal of Hazardous Wastes' for Ma laysia. Un li ke most Western industrialized countries which have established water-borne sewerage sys tems enabling industries to di spose of their effl uents after meeting the standards required by the respective Auth ority , industries in Malaysia di scharge alm ost exclusively to open stormwater drains and surface waters . Indus~ies are now required to meet stringe nt industrial effl uent standard s and regulations wh ich were introduced by the Division of the Env ironment in January 1981 compelli ng most industries to insta l on-site treatment plants. The speakers described the results including increasing quantities of sludges for wh ich there is no satisfactory disposal outlet at present. Slides illustrated the problems arising from the di scharge of hazardous untreated wastes to the environment and the possible health and environmental problems resulting . Also illustrated were examples of well designed treatment plants now being installed in Malaysia. The speakers concluded by outlining strategies, methods of treatment and of disposal which will enable so lutions to the prob lem by th e Malaysian Government. On Apri l 21st a joint A.W.W.A. and I. E. Aust. meeting attracted a capacity attendance for a seminar on 'Energy Dissipation in Hydraulics' at the S.R.&W .S. Commission's theatrette. Proceedings commenced with two video tapes from the United States Bureau of Reclamation, the fir st dealing with th eory

and mod el test in g for cav itation while th e second desc ribed problems which had been ex perienced and soluti o ns adopted to overcome the problems . Then fo ll owed the fir st paper prese nted by Eric Lesleighter of the Snowy Mountain s Engineerin g Co rpo ration on research int o probl ems ex peri enced at Dartmouth where seve re cav itation ha s been exper ienced do wnstream of the low level contro l gates. Eric described laboratory experiments carri ed out by SMEC, details of a model test o n th e Da rtmouth ou tlet s and conclud ed wit h a film o n th e model. A different note was int rod uced by Jack Maver of th e State Ri vers and Water Supply Commiss ion who desc ribed cavitation a nd other problems encountered a t Tarbell a Dam in Nort h Pakista n. Severe cavitation and mass ive fa ilu res were ex peri enced in the di version tunne ls when the reservo ir was drained to rein sta te sink ho les in th e bla nk et covering the a llu vium under t he reservo ir and the dam it self. Slides sho wed damage at Tarbell a and detail s of restoration adopted on that job. Keith Murl ey o f the State Ri ve rs desc ribed in detail damage experi enced a t Dartmouth Dam and a proposa l to cons truct ra mps in th e line of flow to induce th e entr y of large vo lumes of air from the access tunnel, whi ch has been recommended to th e Ri ver Murray Comm ission fo r adoption at Dartmouth. The meeting concl ud ed with ent husiast ic thank s to the speakers and to th e Commission for its excell ent accommodation a nd hospit a lity.

New Members Welcome to new Sustainin g Member Albright and Wi lson (Au st. ) Ltd. and th eir nomin ee Mr P. H . Strasser and to a new Member , Les Rya n of th e State Ri vers and Water Supply Commi ssion.

Coming Events •

Jun e 22nd: As we go to press, a meeting o n 'Testing of Loy Yang Salin e Waste Outfall Pipeline' - L. A. Reill y and M. E. Hannan-Smith . Ju ly: Date to be advised , mid- year social fu nction , Ladies' night. Jul y 27 th: Paper o n Sewerage Strategy or Water Planning' Offi cers of the

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M.M .B.W. Aug. 24t h: 'Slow Sand Filtration' Wayne Drew a nd Gordon Hirth. Oct. 9th & 10th: Spring Breakout at Bendigo .

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CHANGING YOUR ADDRESS? PLEASE LET US KNOW! NOTIFY ADDRESS CHANGES TO YOUR BRANCH SECRETARY OR THE EDITOR ADDRESSES PAGES 1 & 7

Sec retary-Treas urer will visit Brazil to pursue thi s poss ibility with th e '>B razili a n Nat io nal Committ ee a nd o th er interested parti es . Offe rs were accept ed from th e UK Co mmi ttee to ho ld th e 1988 Co nference an d fro m th e Japa nese Co mmit tee to ho ld th e 1990 Co nference.

REGIO AL AND SPECIALISED CONFERENCES

THE CHAIRMAN REPORTS GOVERNING BOARD MEETING NAME CHANGE Th e headin g is not a mi sprint. Th e Association has changed its na me . The origina l na me of th e Assoc ia tion co uld give t he impress io n tha t the Assoc iation was co ncerned on ly with academic resea rch whereas th e stat ut es pro vide for in vo lvement in all aspects of water pollution control including the design a nd operat ion of treatment pla nts and th e management of treatment plants as well as pure and applied research . At th e Capetown meet ing of th e Boa rd it was decid ed to add to t he title the word s 'a nd Control ' to indicate the wider interest . Our name has now become the 'I nternational

Association on Water Pollution Research and Control'. Th e statutes wi ll be reviewed accordingly.

FINANCES Fin a nces are health y but to meet infl atio n and changing exchange rates, it was agreed that subscripti o n leve ls sho uld be rev iewed regu lar ly on a two yea rl y basis beginnin g in 1984. Renegotiation with Perga mon Press sho uld res ult in a substanti a l in crease of income from pub li ca tion s . Subscr iptions co uld of co urse be reduced if membership increased and a membershi p dri ve is to be undert a ken.

ELECTION OF EXECUTIVE Professor Dick Engelb rec ht was re-e lected Presid ent a nd Pro fessor Ha rremoes and Dr Kunt ze as Vice Pres ident s. Ted Wald er was rea ppointed C hairman of th e Fin a nce Co mmittee .

BIENNIAL CONFERENCES As previously ad vised, th e 1984 Conference will be held in Am sterdam . As well as the usua l genera l sess ions, th ere will be three special th emes: I. Sewage Treatm ent Special Problems; 2. Estua ri es, Ma rin e Waters a nd Inland Seas: and 3. Int eract io ns Betwee n Parti culate Matter a nd Wa ter. Co nfe rence dates wi ll be 17t h to 20th September and th e major water industry exhibition , Aqua Tec h 1984 , will be held in co njuction with th e co nference . Th is timing will benefit delegates a nd there will be finan cial benefit s to I. A.W.P.R.C . from th e joint operation. The I 986 Co nference wi ll probabl y be held in Rio De Jani ero a nd the President a nd

A tota l of 13 co nfere nces has bee n a ppro ved a nd a furth er fo ur proposa ls a re bein g co nsid ered. Detail s o f these wil l be prov ided in a future iss ue o f ;Water '.

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WORKING AND STU DY GROUPS The Governing Board rece ived reports from th e joint 1.A.W . . R. C. / l. U.P.A.C. Wo r ki ng Group on Notation, Th e Stud y G ro up o n Water Viro logy, Th e Wo rki ng Gro up on Fa te and Effects of Po llut a nts in Natural Wa ter , Th e Worki ng Grou p o n Water P o ll ution fr o m Alternat ive Energy Sources, T he Stud y Gro u p o n Biolog ica l Ph osp·horu s Remova l and St ud y Gro up o n In strumentation for O n-Lin e Measurement. lt was agreed to approve the fo rm at io n of a furth er Work in g Group on Co mput eri sed Pub licat ion in order to keep a breast with mod ern develo pm ent s a nd to report on th e poss ib le fut ure effects o n Associat io n fun d in g. A report was rece ived o n di scuss io ns co n ce rnin g t h e formation of a n l. A .H .R ./ l. A.W.P.R.C. joint co mmitt ee on urban sto rm water drain age.

EXECUTIVE EDITOR REPORT Problems with th e pub li cat ion 'Water R esea r c h ' a nd 'Wa t er Sc ie n ce a n d T ec hn o logy' have been overco me and th ey a re no w bein g produced o n a regula r bas is a nd the back log of pa pers to be published is redu cing. As reco mm end ed by th e Au stral ia n Nati o nal Co mmittee the in sid e cove r notes of 'Water Research ~ will now give better guidan ce to a uth ors on the submi ss io n of papers . The Austra li an Nat iona l ·Co mmitt ee will be a point of Reference fo r papers whi ch may be subm itt ed by Austra li an aut hors . Thi s should ass ist in ove rco ming past co mmuni cation problems. Th e News lett er has bee n comp letely redes igned a nd the latest iss ues a re co nsid era bl y improved res ulting in req uests fro m advert ise rs fo r space .

CRITERIA AND GUIDELINES FOR REGIO NA L AND SPECIALISED CONFERENCES A docu ment prepared by Professor Jon es of Ca nada was adop ted subj ect to minor cha nges . Thi s docum ent will be most va lu a bl e when co nsiderin g proposal s for sponsorship or co-spo nsors hi p of these co nfere nces. lt wo uld ha ve o ve rcome some of the mi sunders ta ndin gs wh ich occurred recentl y with A.W .W.A. regard in g th e Darwin Co nfere nce.

FI NANC IAL MA NAGEMENT A document dea lin g with th e Financial ma nage ment of the Association includin g WATER

1j \

guid elines for reimbur se ment of expenses to hono ra ry office rs a nd th e li ke was adopted . Thi s will be a ve ry use fu l ad diti o n .

THE CAPETOWN CONFERENCE Th e Confere nce was a n o ut sta ndin g success wit h 650 reg istered d elegates plus a pprox im a tely I 80 accompa n yin g perso ns . About ha lf th e registra nt s came fr o m ove rseas, 32 co untri es being rep rese nt ed. Th e A ustra li a n de lega tion officiall y numbered 24 . Th e Co nference venu e a t the Nico Ma la n Centre a nd th e Civ ic Centre was exce llent a nd apa rt fro m the usua l lost bu ses a nd such , a ll arra nge ment s work ed o ut very well. Th e sta ndard of papers va ried as usua l, a nd a notewort hy aspect was th e very strong support give n to the State o f the Art sess io ns . Th ere were very good poster di spl ays and stocks o f ex pl anatory lit erat ure. T he recepti o ns, ente rt a inm ents, a nd hospit a lit y were a lmos t overwhelmin g as were th e sup pli es of the exce llent loca l whi te win es.

developments . A ft er many experim ents with revegetation of dumps it is now proposed th at they be covered with a layer o f concrete to prevent erosion and d ust storm s. A visit was a lso paid to a plant treating acid min e wastes prior to discharge to a water co urse. Evaporation ponds a re a lso used but do not seem to be 100 per ce nt success ful. A full day visit was paid to the enormous a nd complex new coal to oi l conversion plants, S .A.S .O.L. 2 and 3. T he objective is to operate on a closed cycle with a ll watery wastes being full y treated a nd returned to process. T he very ex pensive treatment plant includes post filtration , and act ivated carbo n units. Organic sludges are in cinerated. There is still a hi ghl y sa lin e res idue which has so far baffled th e Co mpa ny whi ch has tried spray evapo ra tion a nd evaporation ponds, but , in spite of the grea t excess of evaporation over ra in fa ll , this work ha s been unsuccess ful and other so lutions are being so ught. A lso visi ted was the sma ll treatment plant at Su n C ity for the rem ova l of nutri ents by

Director John McCann Director Gutteridge, Haskins and Davey , Consulting Engineers, N W.

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The Australian co ntin ge nt in full voice Out sta ndin g was th e barbec ue held at th e Bi e n Donn e ex p e r im e nt a l farm. Th e A ustralian delegat io n o bli ged with th e 'National Ant hem ' - 'Waltzing Mati lda ' (see the ph otograp hic proof). Th e cheese a nd win e far ewe ll fun ction was most impress ive with tables d eco ra ted with ' ho rn s of plent y' overflo win g with fruit a nd fl owers. T here was food in profusio n a nd wine by the mega litre. Th e tec hni cal excursio ns included vis it s to two mode rn sewage trea tm ent plants a nd a water recla mation p la nt a ll co nta inin g some int eres tin g new deve lopment s. Visit s were a lso ma de to th e nucl ear power sta tion with a lecture on th e va ri o us was tes from th e pl a nt.

POST-CONFERENCE SEMINARS So me 250 delega tes registered for th e postconference semina rs at Pretoria. Held at the C.S. I.R . Training Centre wit h faci lities superio r to a ny in Austra lia. T he seminar on Mining Wastes visited o ld tailings dumps whi ch w_ere bein g slurried a nd pumped to a ce ntral treatment plant for the recovery of uranium and gold. T he residua l so lids are pumped some 15 km to a new di sposal area, fr ee in g th e or ig in a l s ite s for urban WATER

yes, 'Waltzing Matild a'.

biological a nd precipita tion processes and by sand fi ltrat ion and chl or ination prior to di scharge to a n artificia l lake which is part of th e casino entertainment centre.

Director Dr Trevor Judell Member of the Governing Board , Director Judell, Platt, Thomas and Associates,

Consulting Engineers, N.S. W. ,f

PRE-CO NFERENCE TOURS T he pre-con ference tour to Kruger P a rk was hi ghl y prai sed for th e arrangements with a few comp la ints of non co-operation by t he fauna which seemed to pre fer the wrong side of th e road or th e shelter of bushes . The waste treatm ent plants at t he rest ca mps were not so elu sive.

A.N.C. DIRECTORS Present Directors of The A ustra li a n Nationa l Co mmittee are Mr John McCann , Dr Trevor Judell a nd Dr Brian Bolto . Bio-data has been published previous ly in t hi s Journal and in thi s iss ue we prov id e photograph s. Director strength has been a ugmented by th e co-optin g of Pro f. Jack Lawson (Melb.), Mr Don La ne (S.A. ) and Dr David Garma n (Syd.) , pend ing the necessa ry co nstitutional cha nges to in crease th e number of Directors. LEON HENRY C ha irman

Director Dr Brian Bolto Assistant Chief, Division of Chemical Technology, C.S.I.R.O., Vic.

PROTECTIVE COATINGS FOR WATERWORKS STRUCTURES: SOME EXPERIENCES OF THE SR&WSC L. A. Reilly and T. J. Richards 1. INTRODUCTION It is difficult to genera li se about protective coatings for waterworks structures beca use of the large number of different coatings encountered. Broadl y, the coatings may be classified into inorgani c and organic types: INORGANIC (a) oxide film s weathering steels and anodised aluminium deposited from hard waters (b) calcite film s (c) cement mortar lining of M.S. pipes galvanising a nd zinc-d ust paints (d) zi nc coal tar enamels (a) thick films ORGANIC fusion-bond ed low density pol yeth ylene extruded high density polyethylene epoxy mortars PVC linings (b) thin film s-paints non-convertible types-chlorina ted rubber vinyl convertible types-alkyd epoxy polyurethane In this short paper, the di scussion is restricted to zinc-dust primer and some of the organic paints. Section 2 draws upon the State Ri vers and Water Supply Commission's recent experience of using zinc-dust primer under non-convertible paints. These protective systems are of good quality when they are applied satisfactorily, but there are application problems which need to be understood. Section 3 stresses the need for good surface preparation and what that means-and the trouble which will develop if a prepared surface is not chemically clean as well as visually clean. Finally, Section 4 dwell s upon the need to exercise very close control of the mixing of multi-component epoxy paints if a satisfactory coating is to result. In particular, the use of excess of the cross-linking ("hardener"), component is undesirabl e when the painted item is to undergo water immersion.

coat ing consists of zinc particles in a silicate matrix. The silicate matrix is chemically bonded to both the zinc particles and the steel surface (Munger, 1975). The usual requirement is that the thickness of the dried primer film should be between 65 µm and 100 µm. If the thickness is less than 65 µm there is a ri sk that the pain t will not cove r he peaks on the abrasive-blasted surface while coati ngs thicker than 100 µm are not recommended because shrink age of the film on curing can cause 'mud-cracking' . The excellent performance of these coatings is the result of two different properties; the strong adherence of the coating to the steel surface and the cathod ic protection from the presence of zinc in the dried film which prevents corrosion of the underlying steel (Jaeger and Sherwood, 1975) . It has been claimed (Rogers et al., 1981) that the inorganic zinc primers give protection comparable to that provided by hot-dip ga lvanising and it is easier to ensure satisfactory adhesion of subsequent paint coats to the inorgan ic zinc primer than it is to get paint coatings to adhere to galvanised surfaces. Inorga nic zinc primers have excellent resistance to severe env ironments, provided the pH is within the range five to nine, and are not susceptible to underfilm corrosion when applied to a correctly prepared surface (Rogers et al., 1981).

BINDER

ZINC PARTICLES

2. INORGANIC ZINC PRIMERS The current specification for painting of the steel storage tank s of the Main Urban Supplies Division of the State Rivers and Water Supply Commission requires an inorga nic zinc primer in an ethyl silicate veh icl e for both the interior surfaces of the tank and for the exterior su rfaces which are on ly exposed to atmospheric conditions. Inorganic zinc paints were developed in Australia and the first major use of these paints was on the Morgan-Whyalla pipeline which was completed in 1944. No top coat was used and the inorganic zinc paint provided protection for the pipeline for much longer than the original 20 year guarantee period (Munger, I 97 5). These paints consist of zinc du st, with a particle size in the range six to 30 µm, in a si licate binder. The cu red coating contai ns no organic materia l so the paints are referred to as inorganic zinc paints to distingui sh them from other zinc-rich paints, such as the zinc-epoxy paints, which use an organic binder. Over the years there have been many different methods used to produce the cured film which binds the zinc particles together. The ethyl silicate binder used in the specified paints cures by reacting with moisture so that the ethyl radicle is lost as ethanol and the fin al cured

Lawrie Reilly is Principal Materials Scientist and Trevor Richards is Senior Materials Engineer of the Water and Materials Science Division of the State Rivers and Water Supply Commission of Victoria. 14

Figure 1. Schematic representation of the structure of an inorganic zinc primer. 2.1 Problems in Overcoating Inorganic Zinc Primer The specification referred to above requires that the inorganic zinc primer should be overcoated with a suitable paint. Vinyl (VR3) paint is used on the interior surfaces of the tanks and, when the tank is situated in a severe corrosive environment such as a coastal area, a chlorinated rubber paint is used on the exterior surfaces. Some difficulties have been experienced in overcoating inorganic zinc primers with these paints. The problems arise both from the nature of the inorganic zinc coating and from the types of paint used for overcoating. Because of the need to maintain a hi gh zinc content in the cured primer so that there is a reasonable amount of contact between the zinc particles, the WATER

coatings are porous to some extent. This is shown schematically in q uirement has largel y developed from the need to ensure sat isfactory Figure 1. The vin yl and chlorinated rubber paints are non-co nvertible performance from paint coati ngs under adverse conditw ns such as encoati ngs, no chemical reaction takes place to cause the film s to harden cou ntered by oil prod uction platforms in the North Sea. If a steel surand the harden ing process is due so lely to the loss of solvents from the .face has been contami nated by ch loride ions or sulphate ions, this conpaints after they have been appli ed to the sur face. tamination wi ll not necessarily be removed by abrasive blasting, and When a non-convertible coating is applied to a porous surface, so l- so luble ferrou s sa lts, chl orides or sulph ates, may remain on the survent fro m th e paint moves into the pores and at the same time so lvent face under the paint film. Because all paint films are permeable to is lost from the surface by evaporatio n. Th e result is a coating that has water and oxygen to some extent, a cyclic corrosion process will be set formed a skin on the surface but still contains so lvent and entrapped up where rusting occurs under the paint as a direct conseq uence of the air in the porous primer coat. The so lvent and air try to move out to chem ical contam inants on the surface. This process is illustrated in the sur face, but because of the reduced permeability of the sk in , Figure 3 and it can be seen that the contam in ating an ion is regenerated become trapµed just in side the paint film a nd tend to form bubbles in d uring the process and, as a result , large volum es of rust can form and the pain t film . This process is shown in Figure 2. disrupt the coat ings.

CHLORIDE+ WATER

SKIN FORMED ON PAINT SOLVENT TRAPPED IN PORES \ IN PRIMER

HYDROCHLORIC ACID LARGE VOLUMES OF RUST

STEEL

FERROUS CHLORIDE

Figure 2. Bubbling of non-convertib le coatings applied over inorganic zinc primers is du e to solvent trapped in the pores in the primer.

The problem appears to be worse when the sur face temperature is hi gh, causing rapid skinning of the sur face and rapid evaporation of the so lvent within the pores. Wind y conditi ons during painting a lso tend to cause bubbling of the topcoat, presumably because the movement of air over the surface of the paint film causes the sur face sk in to develop even more rapidly. There are several ways to avo id the problem . A seal coat can be applied over the inorganic zinc primer before the topcoat is applied; this coat ing sea ls the outer pores in the primer, disp laces the air from those pores and prevents movement of solvent from the topcoat into the underlying primer. Paint manufacturers are look ing at changes in formulation, such as modifications to the solvents used, to minimi ze the problem. 3. SURFACE PREPARATION FOR PROTECTIVE COATINGS

Surface preparation is the most important phase of applicat ion of any protective paint system. Poor surface preparation is probably the most important si ngle factor responsible for the premature fa ilu re of pain t coatings (Tator, 198 1). For inorganic zinc silicate primers the minimum recommended standard of abrasive blast cleaning is Class 2 ½ , AS 1627.4 (SAA , 1974a) or " near white" blast cleaning, but the SR&WSC requires Class 3, "white metal" blast cleaning. Abrasive blast clean in g removes mill sca le, a comp lex layer of iron oxides, from previously unpainted steel and produces a surface to which the paint ca n ad here satisfactorily. If the mill scale is not removed compl etely, local corrosion ce ll s are set up between the mill scale and th e neighbouring steel, rusting begins under the paint film and there is rapid di sruption of the film (Plaster, 1972). The roughened surface produced by the blast increases the area over which adhesion can be developed between the primer and the steel (Rogers et al., 1981). It is important that the surface roughness or "surface profile" is sufficient to provide adeq uate area for ad hesion but not so great that the high peaks mean that large quantities of paint have to be used to fill the valleys between the peaks before the peaks themselves can be covered with a suffi cient thickness of paint. In recent years it has become· apparent that , in addition to the physical cleaning provided by the abrasive blast, it is important that the surface shou ld also be chemically clean (McKelvie, 1977). This reWATER

WATER+ OXYGEN

Figure 3. Cyclic corrosion processes which occur on surfaces contaminated with chloride ions.

Ch loride contamination of steel sur faces can occur in both coastal and industrial environments . The Commission is currently looking at tests wh ich wi ll show whether the contam inants have been removed from steel structures by the blast cleaning operation. If the tests show that the sur face is still contaminated after blasting, further preparation, such as washing the surface with water and reblasting , may be required to ensure maximum life from the coating . Sand is the abrasive used for most blast cleaning in Victoria . It is a very effective abrasive and has the advantages that it is cheap and it is not too harsh so that it produces a satisfactory profile height under most blasting cond itions. When the sand grains strike the surface they are broken into smaller pieces and there is a risk of silicosis as a resu lt of inhalation of the fine particles. For this reason sand can not be used for blasting in most other states and it is lik ely that its use wi ll be restricted in Victoria within the next five years. 3.1 Failure of a Coal-Tar Epoxy Paint A case where poor surface preparation is thought to have caused premature fa ilure of a paint system is the early fai lure of a coal-tar epoxy paint used as a lining for a steel tunnel. T he tunnel is the main o utlet from a large water storage. Const ruction involved excavati ng a tunnel through rock, positioning section s of steel liner in the rock and welding sections together to form a continuo us tunnel. T he space between the steel liner and the rock was then grouted. The paint specified for the lining was a solventless coal-tar epoxy; a solventless paint was chosen because there is less chance of pinhole defects in the finished coating as a result of solvent entrapment in the paint film. Coal-tar epox ies require good surface preparation for satisfactory performance. T hey fu!lction by forming a thick (400 µm) barrier between the corros ive environment and the steel. The contractor had or iginally intended to paint the tunnel sections in a workshop on the site and then weld the painted sections together underground. It soon became apparent that the traffic in the tunnel

was causing considerable damage to the paint on the invert of the tunnel and it was decided that the invert wo uld not be painted until the tunnel was finished. The partly painted section s were stored in the open a ir for more than a year befor e being placed in th e tunnel a nd there was co nsiderable ru sting of th e unpainted in vert . When the sectio ns were welded in place, water in the tunn el a nd co nt amin ati on from the grouting operation caused further ru sting of the unprotected steel of the invert. Rust pitting occurred, particularly adjacent to the weld s . After th e in vert had bee n re-b las ted to Class 3 standard and painted- not an easy task because of the co nditions in th e tun nel-and the tunnel placed in serv ice, it beca me a pparent that the paint coating on th e in vert was not giving sat isfactory performance. Inspection showed areas where th e paint had disbonded and where water had penetrated the coating. The most li kely cause of this fa ilure was inco mplete removal of the co ntaminants from the sur face when the sur face was prepared for painting. Tests showed that so luble ferrous salts were present on the steel surface in areas where water had penetrated the coat in g. These salts probabl y had been left on the sur face after abrasive cleaning and had allowed corrosio n to occ ur under the paint film by the process in dicated in Figure 3.

2H V) V)

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= _J

2. 0 2.2 1. 8

'-'

z w

0...

2.4

3B 4B

2.6

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6B 0

Figure 4. The effect of temperature on the hardness of epoxy paint mixes . The figures bes ide the curves indicate mix ratio , resin : hardener.

useful , but cou ld not be used under a ll condit ions because the temperat ure of the paint film influ enced the res ults , see Figure 4. The test did however allow so me assess ment of the problem. A visit to the pla nt where th e linin g was appli ed showed th at th e problem la rgely arose because the autom ati c meter in g equ ipment used to dispense the co rrect quantities of resin and hardener tended to drift with time. The operators were unaware of this problem and assum ed that the eq uipm ent gave the co rrect mix rati o. As a res ult, incorrect mixes were a pplied to a number of pipes and fittin gs . Wh en the contractor wa s show n that th e incorrect mixes resu lt ed from the drift in th e equi pment he took immed iat e steps to ens ure th at the mi x ratio was checked at regu lar in tervals . Furt her investigat io ns were directed to determining the effect of changes in mi x ratio on the phys ica l properties of the coating. The compo nents in the pa int were st ipulated to be mixed in the ratio of two parts of harden er to one part of resin. It beca me apparent th at changes in properti es we re much more obvi~us when excess harde ner

2H (/) (/)

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u z w

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4.1 Laboratory Investigation of Epoxy Paint Mix Ratios

Durin g the linin g operation for the saline water pipeline it beca me apparent that th ere was so me va ri ation in th e ratio of th e two co mponents in the epoxy paint used for lining th e pipeline. Many pipes and fittings were rejected because the lining had not hardened. The first investigation was to develop a si mpl e field test to determine whether or not a given lining had been prepared using the proper ratio of components. A pencil ha rdness test , in which the hardn ess of the paint film is given by the hardness of the hard est pencil lead that wi ll not sc ratch the paint surface (SAA, I 974 b), was found to be

TEST TEMPERATURE,

4. EPOXY PAI NTS

The use of a hi gh-build so lvent less epox y paint for lining of a steel pipeline carryin g sa line water led the Commissio n 's Materials Eva lu ation Section to carry out severa l in vesti gations whi ch resulted in a better understanding of this type of paint. Epoxy paints protect primaril y by providing a barrier to the movement of iron io ns away from the steel surface. Because a ll pain ts, including epoxies, are permeable to both water and oxyge n to so me extent, it is not poss ible to prevent a corrosive micro-e nvironment for ming at the steel sur face underneat h th e paint film . The corrosion process can only continu e, however , if the iron ions produced by the corrosion reaction can move away from the sur face (assuming that the surface was originally chemicall y clean, see Section 3). If the iron ion s remain at the surface they effectively st ifle furth er react ion . Correctly mixed and cured epoxy coati ngs are essentially a single large molecule where chemical reaction between th e two components, . the resin and the hardener, has caused the sma ller molecules to crosslink to form a giant molecule. If the two components a re not thoroughly mixed in the co rrect ratio, areas of the paint coating will have a lower cross-link density and will be more permeable to iron ions, allowing corrosion to proceed under th e paint film. Manufacturers usually suppl y epoxy paints in packs with the correct quantities of hardener and resin packed in separat e co ntainers a nd th e intention is that the entire contents of th e two co nt ainers should be mixed together immediately prior to application, to give a batch of paint. Unfortunately there is a cost penalty associated with sma ll (e.g . fo ur litre) packs, and painting con tracto rs prefer to buy the pai nt in larger (e.g. twenty li tre) packs. Once the paint is mixed it has a relativel y short pot life a nd co ntractors often try to mi x quantities less than th e standard Âˇpack size to finish a particular area. A typi ca l cove rage for a high-b uild epoxy is 4 m'/ L a nd, faced with only 20 m' to paint, a cont ractor may try to mix about five litres of paint from a twenty litre pack. If the correct resin to hardener ratio is 2 : I, a five litre mix would require 3.33 litres of resin and 1.67 litres of hardener. It obviously requires great care to measure these quantities exactly. Any error in meas uring th e q uan tities means that not onl y is th e mix ratio incorrect for th e small batch mixed, but the quantities of resin and ha rdener remaining in the con\ainers are no longer in the correct ratio a nd it is lik ely that the ratio of co mponents will be incorrect in subsequ ent batches.

6B 1. 2

1. 6

2.0

2.4

2.8

PESIN : HARDENER RATIO Figure 5 . The effect of mix ratio on the hardness of an epoxy paint at

4s c . 0

WATER

was used th a n when th ere was a corres po ndin g excess of resin ; in creas- REFE RENCES ing th e proportion of hardener resulted in a so ft er coa ting . A mi x with Adomenas, A. (1 974) . Epoxy Resins, Ch . 2. JO in 'Sur face t.oatings' , Oil and a resin to hardener rati o o f 1.8 : 1 was so ft er th a n t he correct mix Colou r Chemists Associati on , Australia (N .S.W.U .P.). (2.0 : 1) a nd also so ft er th a n a resin -rich . mi x a t 2. 2 : 1. Thi s can be . J aeger, H . and Sherwood , R. G . (1975). Th e structure of inorganic Zn-rich coat ings examin ed with o ptical a nd electron microscopy. Proceedings of the seen from Fi gure 5. A small excess of ha rdener will ad versel y a ffect Si xth Intern ati o nal Congress on Metallic Corrosion , Sydn ey 1975, 802-8 15. th e wa ter sensiti vit y o f th e cured coa tin g whil e excess resin result s in poo r so lvent resista nce (Ado menas, I 974) . Fo r wa ter imm ersio n ser- McKelvie, A. N. ( 1977) . Steel C lea ning Standards-a case fo r their reappraisal, J . Oil Col. Chem . Assoc., 60, 227-237. vice it is reco mm ended th a t a ny tol erance in the all owed mix rat io Munger , C. G . (1 975) . Inorganic zinc coatings; past, present and future, sho uld no t pe rmit hardener-ri ch mi xes to be used. Materials Performance, May 1975, 25-29. A CKNOWLEDG EMENTS

Th e a uthors ex press a pprecia tion to the Sta te Ri vers a nd Wa ter Suppl y Co mmi ss io n of Victori a for permi ssio n to publish th e pa per a nd to the sta ff o f th e Ma teri a ls Eva lua ti o n Section , Wa ter a nd Ma teri a ls Science Di visio n , o f th e Commission , for th e experimental a nd field in vestiga ti o ns whi ch fo rm ed part of the bases o f thi s paper a nd for ma ny hours o f discussio n o n all as pects o f paint problems.

Plaste r , H . J. (1972). ' Blast C leaning and Allied Techniques' , p . 355. (Portcullis Press). Rodgers , J ., McMahon , W. M. and Weismantel, G . E . (1981). Coatings fo r Steel; Ch . 7 in 'Paint Handboo k', ed. G . E. Weismantel (McGraw-Hill) . SAA (1 974 a) AS 1647.4- 1974), ' Abrasive Blast Cleaning of Steel Surface s' , (Standards Associati on of Australi a). SAA (1 974 b) AS 1580, Meth od 405. 1, 1974, ' Determinatio n of Pencil Hardness o f Paint Film ', (Standards Associatio n o f Australia). Tato r, K. B. (1981) . Surface Preparation: P art II, Ch . 6 in 'Paint Handbook', ed. G. E. Weismantel (M cGraw- Hill).

CALENDAR 1982-83

Oct . 3-8 , St. Louis, Mo . , U .S .A . Wa ter P o lluti o n Control Fed . Conference.

Jul y-7-9, A delaid e, A ust. Co nfere nce o n Engin eerin g Educa ti o n (I. E . Aust.) .

Aug. 31-Sept. 3 , Canberra, Aust. Conference o n Ground water in Fractured Roc k.

Oct. 10-14, San Franci sco, U .S. A . 18th American Wa ter Resources Conference.

July 13 - 15 , London , U. K. Enviro nm ent Eng. Today , Annu al Int. Symposium .

Sept . 5-11, Prague, Czec hoslovakia 16th Congress, Int. Ass . of H yd rogeo logists .

Oct. 19-2 1, Canberra , Au st. Energy 1982 Co nfe rence.

Jul y 19-30, Exeter, U .K . IA HS Symposium o n Adva nces in H yd ro metry.

Sept. 6-10 , Zuri ch 14t h Wo rl d Wa ter Co ngress o f IWSA .

N ov. 2-5 , London , U .K . Lond o n Civil E ng. Con structi o n Show a nd Conference .

Jul y 25-29 , Honolulu , Hawaii 10th Annu al Co nference o f Water Sup pl y Im prove ment Assn.

Sept. 6-10 , Zurich 14th Congress In t. Wa ter Suppl y Ass. Sept. 8-10 , York , U. K. 5 Int Co nfere nce o n Pl asti c Pipes .

July 26-30, Hanover , Germ any 4th Int. Co nference o n Finit e Element s in Wat er Reso urces

Sept. 13- 17, Philad elphia , U .S.A . 3rd Int. Filt rati o n Co ngress .

Jul y 27-30, Lexington , U.S.A . 9th Int. Symposium o n Urba n H ydro logy, H ydra uli cs a nd Sedim ent Co ntrol.

Sept. 14-16, Reading , U .K . In t. Co nference o n fl ow ind uced vib rati o ns in fluid engin eering

A ug. 10-13, Melbourn e, A ustrali a Int. Co nference on Fracture Mecha ni cs Tec hn o lo gy.

Sept. 14-16, Southampton , U. K. Sho relin e P rotecti o n.

Aug. 16-18, Copenhagen, Denmark Int. Co nfere nce on Coa l Fired Power Pl a nt s a nd th e Aqu ati c Enviro nm ent.

Sept. 20-24 , Eastbourne , U .K. I 982 Meeting, In st. of Wa ter P o lluti on Cont ro l.

Aug. 16-20 , Melbourne, A ustralia 6t h Int. Co n fe rence o n Strength s o f Metals a nd All oys

Sept. 2 1-23, Berne, Switzerland WHO Int . Symposium o n hydro logical resea rch basins a nd th eir use in water reso urces pl a nnin g.

A ug . 21 -23, A rmidale , N.S .W . Conference o n Agri cultura l Engin ee rin g (I. E . A ust.) A ug. 23-27 , Melbourne, A ust. A RRB Eleventh Conference . Aug . 24-26, A uckland, New Zealand 1982 N.Z . Wa ter Co nference .

Sept . 22 -24 , Cove ntry, U. K. Int. Co nference o n H yd ra uli c Mo delling of Civil Engineerin g Stru ctures. Sept. 27-Oct. 2, Varna, Bul garia In t. Sym posium o n compu tati o n of gro und wa ter ba la nces (U NESCO) .

No v. 14- 19, Capetown , S. Africa 18th Int. Conference on Coas tal Engin eerin g. No v. 30-Dec. 2, Ca nberra, Australia Sy mpos ium o n Predi ction of Wa ter Qualit y (A ust . Ac . o f Science). Dec. 2-3 , London , U .K. In st. of Wa ter Engin eers & Scienti sts Symposium , Microtechn ology Dec . 5-8, Nashville (ten.), U.S .A . Wa ter Qu ality Tec hno logy Co nference

1983 Jan . 16-19, New York , U .S. A Meeting o f Water Pollution Control Federat ion . March , Qu een sland , Au st. Conference on Coasta l Engin eering . March 1-4, Mexico City Aqua Mex . '83 Int. Wa ter Technology Ex. a nd Co nference (Wa ter Decade 198 1/ 90) . March-April , Qu eensland , A ust. Eng. Conference o n Tunnellin g. April 11-15 , Sydney, Aust. AWW A 10th Federal Con vention.

A ug. 24-26 , Bandung , Indonesia 3rd Congress of Asia n & P ac . Di v. Int. Ass . H yd . Res.

Sept. 27-30, Toowoomba , Q'ld . Au st. Symposium o n Rural Drain age in No rth ern Australi a.

May 9-11, Perth, W. Au st. 53rd A NZAAS Congress .

Aug . 25 -27 , Newcastle , Au stralia 2nd Co nference on Co ntro l Engin ee rin g (I. E. A ust.) .

Sept. 28-Oct. I, Asilomar, Cal. , U.S.A. Impacts o f Limi ted Wa ter for Agri culture in th e Arid West .

May 16-20, Brisbane, Queensland Annual Scientific Meeting, Soc . of Microbiology .

WATER

Melbourne Water Distribution System Corrosion and its Mitigation THE WATER DISTRIBUTION SYSTEM

The system involves: • 2 040 km of wrought iron and mild steel pipe laid from 1889 to the prese nt and ranging in size from 300 mm to 2 100 mm . In the early days, external coat ings were largely ineffective in preventing corrosion but since the second world war, coal tar enamel external coatings combined with improvements in trench refill practices have provided an extremely effic ient protective system. Cement mortar linings are used for sizes up to 900 mm and coal tar enamel linings are used for larger diameters. • 1 950 km of asbes tos cement pipe varying in size from 80 mm to 225 mm. Asbestos cement pipe was first used in 1928 but its use was discontinued in 1960 because of the phys ical deterioration experienced . Approximately 20 km per annum are replaced with cast iron pipe. • 9 920 km of cast iron pipe laid from 1857 onwards in sizes from 80 mm to 750 mm . Pipes laid before 1927 were unlined but since then all cast iron pipe laid has been lined with cement mortar a nd a programme for cement lining in situ of the remaining unlined pipe will be completed about 1984.

vices directly to the ferrous main. It has been estimated that 75 to 80 per cent of reti culation main repairs are d ue to bimetallic cell corrosion. Copper service pipes also adverse_Jy affect galva nised wrought iron pipe used in nearb y services and this effect is aggravated by the use of the water service piping as part of the multiple-ea rthed -neutral (M.E.N.) elect rical suppl y earthing system . • Corrosion from the M.E .N. system has caused a growing prob lem with the in troduction of household appl iances using half wave diodes which produce direct current from alternating current. This direct curren t aggravates the copper-iron co rrosion pattern . Tests have shown that all of the added direct current discharges from the ferrou s metal

sidered to be well adjusted, which permits more attention to improved protection of the balance of the distribution sys tem . Sufficient data has now been obta ined to permit predict ion of the behaviour of mild steel water mains in the future . This has permitted li sting of section s of mains with differing electrical or phys ical characteristics and the gro uping of th ese mains according to the present co rrosion status of each . Four groups are used: km sections (a) Fu ll y protected-life indefinite 400 200 (b) No perforations to date 1200 650 (c) One or two perforations 100 50 (d) Three or more perforations 300 100

100 90 V)

FURTHER DRAINAGE CO NNECTIONS AND SYSTEMS ADJUSTMENTS .

f<(

0::

FORMS OF CORROSION

Corrosion experienced in the Melbourne distribution system is generally of the fo llowing nature: • Corrosion due to stray traction currents which became a prob lem with mild steel main s when tram and train systems were electrified between 1906 and 1929. These effects are now largely controlled by the traction drainage schemes installed and adj usted by the Victoria Electrolysis Comm ittee. Cast iron and wrought iron pipes show lit tle effect from stray traction current, probably because of low electrical cond uct ivity through the adjoining materials . • Corrosion due to bimetallic cell effects is a minor problem in th e mild steel pipe system, la rgely because copper is rarely used in conjunction with that material and has always been insu lated from it. The usua l facto rs affecting steel pipe are the in terconnection of new and old pipe and va rying env ironm ental conditions such as anaerobic clays or direct embedment in concrete. A major problem from this corrosion fo rm · occurs wi th the major reticulation material, cast iron, whi ch has been severely affected as a result of the practice of tapP,ing copper se r-

This paper is based upon notes of a talk delivered by Mr Brian Hatfield, Deputy Electrolysis Engineer of the Melbourne and Metropolitan Board of Works, to !he Regional Conference of the A. W. W.A . Victorian Branch held at the Thomson Dam Construe/ion Township, October 1981.

0::

/\DRAINAGE BOND CONNECTED.

.,1

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20 10 /

~"'

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AGE OF PIPE Figure 1. Mild steel pipe-effect of traction electrification and stray current drainage.

either locally or via the M.E.N. system. None of the current discharges from the copper service. Proposals before the Standards Association of Australia to limit the permiss ible direct cu rrent generation in this type of appliance will have some benefi ts in the future but corrosion wi ll co ntinue at a reduced rate. PROTECTION OF STEEL PIPES

Anti-corrosion mea sures undertaken by the Board have given precedence to the mild steel mains because they are the major water transfer and distribution feeders. Figure 1 shows the effect of traction elecrification on the number of perforations experienced per year in a typical pipeline laid in 1915 and also the benefi cial resu lts achieved by traction drainage systems . These systems are· now co n-

It has been found possible to predict the future perforation pattern for group (d) and th en to generalise this to group (c). This information permits preparatio n of a list of mains requ iring action fo ll owing wh ich assessment of the characterist ics of each pipe section all ows appropriate corrosion prevention measures to be defined for inclusion in a works programme. With group (b) where no perforations have •occurred, the above method ca nnot be used to predict the future behaviour of the main s. By the use of potential survey techniques, it is ant icipated that corroding areas will be located and appropriate act ion taken to limit the rate of corrosion . In addition , continued monitoring of the gro up (a) main s will ensure that their protection level is maintained efficiently.

WATER

Current proced ures for minimi sing corrosion of mild steel pipes include: New pipe-a ppli cation of the best coating and linin g wit hin practi ca l limit s -insulation of the main a t connec ti o ns to other pipe work and other points where electri ca l factors may influence corrosio n -application of ca thodic protection to upport the coa tin g - monitorin g of traction problem s Older pipe- replacement where appropriate on economical grounds - monitoring and adjusting traction drainage -application of localised cat hodic protection -provision of nsulation and cat hodic protection -cement lining in situ plus cathodic protection where appropri ate Mr Hatfield pointed out that cement linin g wi th out cat hodic protection is effective for a limited duration on ly. Without ca thodi c protection th e steel continues to corrode and at some tim e in th e future the remainin g metal ca nnot support the pressure on the inside of th e lin ing and large section s of th e pipe wall may fail. In such cases, repairs are often difficult becau se of the a bse nce of sufficie nt so lid metal for the we ldin g o n of pat ches and replacement with new piping is the only economic answer.

CAST IRO

PIPE CORROSION

In the reticulation system where cast iron is the predominant pipe material, the corrosion of the ferrou s meta l by electro lys is and outside electrica l currents is now the principal problem. Considerable wor k has been carried out in analysing data and records to generate the optimum strategy. The analysis has permitted formu lation of life lines as shown in Figure 3 wh ich show the result s for pipes in so il of IO ohm / m resistivit y on ly. Other resistivity va lues wi ll va ry the slopes of the lin es on this fi gure . Investigations of the rapidly increas in g incidence of failures on recently laid main s generated the 25 year life line for pipes weakened by connection to copper services a nd so me effect from DC producing appliances, and then fai ling when stressed by soil movement. Inspect ion of similar situation s in the ground before failure has given an indication of the relative effectiveness of the three factors. At the sa me time in spection of samples of very o ld unlined pipes from near city areas permitted generation of a life line to 100 years and also showed that, in the conditions experienced in fully paved roadways and with relatively few copper services, internal corrosion is much more severe than external corrosio n. It is therefore co nclud ed th at the life of ce ment lined pipe without the aggravating factors of copper services and a pplian ces will co nsiderably exceed the hundred years of past records. Although stray traction currents ca use major problems on mild steel pipes, no such effect is ev ident on cast iron main s . Experience indi cates that joints commonly WATER

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40 50 70 60 AGE OF MAINS I YEARS I Figure 3. Life lines for cast iron mains in soils of 10 ohm resistivity. 10

develop an electrical res ista nce interface bet ween th e pipes and thi s attenuates the magnitude of any stray currents pass ing a long th e pipe. In a ddition, the considerab le length of unlined pipe laid from 1857 onwards a nd st ill in operation demon strates that natural corrosio n in Melbourne' s so il s is not a severe problem. Assessment of the level of corrosion of a cast iron pipe is often difficult in that sampl es retrieved from a burst location often appear to be in a near new co ndition with no obvious corrosion. It is a characteristic of cast grey iron that the iron may be removed electrolytica ll y leaving a graphite matrix which maintain s contour and supports the original paint film. The best method of determining the true condition of the pipe is to sa nd blast one ha lf of the sample to white metal which removes all of the so ft graphite matrix. The major corrosion mechanism active on th e cast iron mains is the bimetallic cell form ed between the pipe and the copper serv ice pipes. Analysis of inspection data indicates that, under these circumstances the life of cas t iron pipes is about 33 years where copper is the predominant service pipe material. This drastic reduction in life, possibly by a factor of IO leads to an estimate of t he number of burst repairs attrib utab le to the corros ion cell of about 2 300 per annum out of a total of nea rl y 3 000 burst repairs. The bimetallic cell corrosion can be prevented by using plastic service pipe or in sert ion of insulat ion between the service pipe and the main. Before undertaking such a change, it is necessary to ens ure the electrical sa fety of workers and consumers and procedures to achieve this are now being finalised.

ADVERSE EFFECTS OF DC PRODUCING APPLIANCES Methods of overcoming the effects of direct currents produced by AC household

100

appliances which use a single diode to provide a low power setting, have st ill to be resolved. T ypical appliances usi ng this technique include some power drill s, hair dryers, fan heaters, coffee makers etc., some of which have been found to produce I Â˝ ampere of direct c urrent in the neutral wire. Because of the interconnection of the electrical earth ing sys tem with water service pipes in Melbourne, some of thi s current flows to earth through the water services. Field tests have shown that about five per cent flows to earth at the initiating property and there will be a similar split of current flow at adjoining properties. Thus one app liance can affect several services. Other tests have shown that when the copper pipe is connected to ferrou s pipe then a ll the appliance cufrent actually flow s to earth from the ferrous pipe with accompanying ferrous corrosion. The magnitude of this problem has been estimated by two different methods with comparab le results . Using the Bureau of Statist ics data on a number of app liances sold and co nverting this to the quantity of direct current produced and metal lost by corrosion , leads to the conclusion that one in three bursts may be attributab le to these units. Alternatively, when the number of house services is combined with the quantity of direct current proposed as acceptable in recent submissions to the Standards Assoc iation of Australia, it is concluded that one in five bursts are attributab le to these units. Where service pipes are insulated from mains, all the direct current from electrical appliances will be restricted to the serv ice piping. Tests have shown that a normal copper house service pipe, 19 mm diameter x 0.9 mm wall thickness subject to the levels of direct current recommended to the Standards Association as acceptable, cou ld fai l by perforation in about seven years. Such a short life cannot be accepted in the water supply industry.

Th ere has not yet been a mar ked increase in fa ilure of co pper services because th ere is usua ll y a la rge q ua ntity of fe rro us metal co nnected to t he copper se rvices and this protects them. In additio n , the a ppl ia nces have o nl y been availa ble in qu a ntity for a bo ut fi ve years. However , it ca n be expected th at there will be a signi fica nt in crease in service pipe fa ilures with the passage of tim e.

GREY CAST IRO N VERSUS DU CTILE IRON PIP ES A fter co mpa rati ve tests o n the co rrosion ra te of grey cast iron and ductile iron pipes,

SEMINARS WATER CONFERENCE 1982 AUCKLAND-NEW ZEALAND AUGUST 24-26

Fourth Nat iona l Water Confer'3nce . Spo nsored by Inst . of Prof. Engineers and Roya l Society of New Zea land. Feature Speaker Prof. Gedaliah Shelef , Israel Inst. of Technology

SYMPOSIA -

tio n of ductile iro n pipe, adopted polyt hene sleeve protect io n fo r a ll s~ch main s. In addi ti on, all services a re ins ul ated fro m the main , leading to a main li fe ex pectancy well in excess of 100 years. M r Hatfield concl uded by indicatin g that the present practices fo r cas t iro n (including d uct ile iro n) a nd mild steel pipes a re believed to give th e best prot ect ion ava ila ble within econo mi c limits a nd the ex istin g tec hno logy . It is a nti cipa ted tha t current practi ces will minimi se t he pro blems whi ch will be exper ienced by opera tors o f th e wa ter suppl y system in the futu re .

CONFERENCES

A.W.W.A.

First Notice

ONE DAY SEMINAR BRISBANE - AUGUST 27

FOURTH INTERNATIONAL CONFERENCE ON CHEMISTRY AND ENVIRONMENTAL PROTECTION

WATER QUALITY ASPECTS OF RESIDENTIAL WATERWAY DEVELOPM ENT

Engin eering , sc ientifi c, deve lopment and management as pec t s wi ll be covered by speakers fro m governm ent and private sph eres.

Toulouse, France 1983

Sept . 19-25,

CALL FOR PAPERS 250-300 wo rd s by Jan. 30, 1983

Themes inc lude : Wat er Resourc e Management , Water Qua lity Management , Urban and Rura l Supp ly, Wast ewater Treatment and Disposa l, Environment .

Members $30, non -members $35, stu dent s $20 . Enquiri es to : Michae l Bowe, Wat er Qualit y Co un c il , GPO Bo x 2454, 4001 . Phon e (07) 224 6714.

Enqu iries : Water Conference 1982, Centre for Continuing Education , University Private Bag , Auckland , N.Z.

WATER QUALITY ASPECTS OF RESIDENTIAL WATERWAY DEVELOPMENT A.W.W.A.

Follows on previous conferences, 1976, 1979 and 1981 . Proceedings 'Physicochemical Methods for Water and Wastewater Treatment' ed ited by L. Pawloski available Permagon Press.

INTERNATIONAL CONFERENCE GROUNDWATER AND MAN SYDNEY DEC. 5-9, 1983

CALL FOR PAPERS Spon sored by Au st. Water Resources Co uncil , Aust . Academy of Sc ience, Int . Ass. of Hydrogeologists and Int. As s. of Hydrological Scien ces. • INVESTIGATION AND ASSESSMENT OF GROUNDWATER RESO URCES • GROUNDWATER AND THE EN VI RONMENT • GRO UNDWATER AND DE VELOPMENT Abstracts 250 words max. to be submitted by Oct. 1st., 1982 to: The Secretary, Groundwater and Man Conference, P.O. Box 1929, Canberra City, ACT 2601, Australia .

using a n impressed cur rent to accelera te norma l co rros io n co ndi tions, it was fou nd tha t , a ltho ugh d uctil e iron pipe corrodes at a bo ut t he sa me ra te as grey iron, the co rrosio n is spread fa irly uniform ly over the pipe a nd it is much less concentrated t han the severe pitti ng corrosio n experienced with grey iron pi pes. The tests also demo nstra ted th e effecti veness of using po lyt hene sleeve wra ppin g o n ductile a nd grey cast iron pipes as a corrosio n inhibitor. T hese tests we re carried o ut shortl y befor e du ctile iron pipe rep laced cas t grey iron pipe o n th e ma rk et a nd th e Board has, alm ost simulta neo usly wit h th e int rodu c-

SEMINAR - ADELAIDE JULY 23 - 3.30-9.30 P.M .

Enquiries: Prof . A. Verdier, Eco le Nati onale Superieure de Chimi e, 118, rout e de Narbonn e, 31077, To ul o use, Cedex, Fran ce.

DISINFECTION OF WATER SUPPLIES

• CURRENT PRACT ICE • TECHNOLOGY & EFFECT IV ENESS • SIDE EFFECTS & ALTERNAT IV ES Enquiries : Dr. J. M. Ro ll s Adelaide (08) 258 1066 or Branch Sec retari es

INSTITUTION OF WATER ENGINEERS & SCIENTISTS

INTERNATIONAL CONFERENCE

OXIDATION DITCH TECHNOLOGY Am sterdam Oct . 5-7 '82

SYMPOSIUM & EXHIBITION MICRO-ELECTRONICS IN WATER INDUSTRY

Process design and se lection , microbio logy and kinet ics , case studies, innovations , waste visits .

LONDON DEC. 2-3 1982 Symposium is fo ll ow-up to th e 1981 report of th e Mi c ro-El ec troni cs Gro up .

Overview by Dr B. A. Heide (Netherlands) and speakers covering U.K., U.S.A., Austria, Be lgium, Denmark, France, Germany.

Enquiri es to: Berna rd Dang erfi eld , In st. of Wat er Engin ee rs & Sci entists , 31 High Ho lbo rn , Lo ndon WC1V -6AX, l.l .K.

Enquiri es to: C_EP Cohsu ltants Ltd ., 26 Albany St. , Edin burgh , EH1 3QH .

U. K. WATER

BOOK REVIEWS NOYES DATA CORPORATION, Park Ridge, New Jersey, U.S.A., specialises in the publication of hard-cover technical and scientific books within a few months of acceptance of manuscripts. Reviews of recent issues follow: Pollution Control Technology for Industrial Wastewater. Ed. D. J. De Renzo, 1981, US $48.

In 720 pages, this book provides an extensive summary of the reliability and effectiveness of 56 unit operations in industrial water pollution control. For each, comprehensive data are given covering: design criteria, common modifications, typical performance, application and limitations, chemicals required, residuals generated, environmental impacts. The descriptions do not provide detailed design or operation information which is covered in general terms only, but the volume is ·most comprehensive on the subject matter it sets out to cover and is good value. A disability is the failure to use SJ. units. JOHN PARKER Wastewater Reuse and Recycling Technology. G. Gulp, G. Wesner, R. Williams and M. Hughes, 1980 US $48.

This 838 page report, prepared under the direction of the office of Water Research and Technology, Department of Interior Washington, is in two parts . Part I covers "Evaluation of Needs and Potential" including water needs and availability in USA, reuse and recycling projects, quality requirements, and potential reuse and recycling. Part 2 covers beneficial uses of reclaimed wastewater, quality criteria for beneficial uses, evaluation of approximately 20 treatment processes, a brief coverage of special treatment considerations for pathogens, organics , and heavy metals , a section on process trains developed to produce effluents suitable for various beneficial uses, including compatibility of treatment systems with reuse. Part 1 gives a reasonable summary of the USA situation, but has little relevance to Australia. Part 2 evaluates processes and provides interesting data for each on operability, effectiveness and reliability, from statistical analyses of various plants. Some processes are covered very lightly, and processes well known in Australia and Europe, receive only brief mentions. Throughout descriptive material is well supported with hard data. DOUGLAS HAMMERTON Potable Water from Wastewater. Ed. M. T. Gillies, April 1981. US $42. This 300 page book describes advances in wastewater treatment technology which can make the production of potable water from wastewater technically feasible. It covers WATER

both direct and indirect use, the former meaning the direct piping of reclaimed water, the latter term applying when a river or lake serves more than one community in sequence. The volume consists inainly of edited and eminently readable versions, of papers presented to the 1st Water Reuse Symposium, Washington, 1979 (A WW A Research Foundation) along with excerpts from four E.P .A . reports ( I 977-79). Developments , not only in America, but also in South Africa and the Netherlands are summarised, with particular details for the Dallas, Denver and Lower Potomac projects. The Chapters covering testing methods and health effects are more up-to-date than most hard-cover material available. A book well worth study, not just for 'potable' reuse, but for all forms of reuse . . E. A. SWINTON Desalination of Sea Water by Reverse Osmosis. Ed. Jeannette Scott, 430 pp ., hard cover, US $39.

This is an edited compilation of nearly 150 U.S. patents, justifiably claimed to eliminate the legal jargon normally found in the patent literature . The earliest patent reviewed dates from 1962, most recent was granted in April, 1980. The book commences with a 16 page introduction to sea water reverse osmosis, and then covers membrane materials (natural and synthetic) membrane supports and casting, membrane treatment and cleaning, equipment configuration and process design, and special techniques. There is little information for the would-be operator of a sea water RO plant, but as the foreword states 'The. information contained in this book wili allow you to establish a sound background before launching into research in this field'. The few groups in Australia involved in RO research will find it extremely valuable, but for the general reader it is too detailed. RUSSELL SMITH

Offshore Ship and Platform Incineration of Hazardous Wastes. Ed. G. V. Hooper, 1981 US$42.

The incineration of wastes on the high seas, either from a specially fitted ship, or from a platform, is an environmentally acceptable method for dealing with potentially hazardous chemicals, since dispersion of residues in the down-wind plume creates a negligible nuisance. This 468 page volume is a collection of several evaluation studies prepared by U.S . Federal and private research organisations, covering environmental assessment, techniques of incineration , and economic studies. One study has proposed to the U.S. Department of Commerce that five ships be constructed by I 989 to deal with an estimated 60 million tonnes per annum of toxic wastes, both solid and liquid. The publication, though strictly applicable .only to the U.S.A., has assembled comprehensive data on the state of the art of

·hazardous waste incineration, and the technical data could be useful to any authority concerned. S. HOLLIS Water Reuse Symposium II, Washington D.C., 1981. AWWA Research Foundation, 6666 West Quincy Ave., Denver, Colorado, US$30. The three volume set is available and the quoted price includes surface mailing to Australia. The 2500 pages of the proceedings present a state-of the art document as covered by the most recent symposium on the subject.

E. A. SWINTON Industrial Effluent Treatment, Vol. 1, Water and Solid Wastes, Ed. J. K. Walters and A. Wint. Applied Science Publishers, Barking, Essex, U.K.£22. This volume is based on lectures given during a series of one week ·courses over the past six years in the Department of Chemical Engineering at the University of Nottingham. Volume 1 deals wfth water pollution and solid waste treatment and ranges over legal constraints, the approach to discharges to sewers and water courses, pollutant effects and biological processes. Case histories are given and two chapters are devoted to the disposal of toxic materials and incineration and pyrolysis of wastes. Compiled from di fferent lectures, the value of the book varies with the background of the reader and ranges from highly academic mathematical treatment of biological processes to down-to-earth advice to industrialists on the range of processes applicable to effluent problems. Applicable to the U .K. scene, much of the information is useful in Australia.

S. Y. IP . Significant Water Usage Publications (1981), the National Capital Development Commission, Canberra. Available from the Commission or through the Australian Government Publishing Service. • Guidelines on Engineering and Environmental Practices - Hydraulics . • Monitoring Stormwater Flow and Water Quality in Paired Rural and Urban Catchments in the A.C.T. • Waters of the Canberra Region. • Monitoring River Recreation Demand in the A.C.T. • Murrumbidgee River Ecological Study. • Utilisation and Protection of the Murrumbidgee River System in the A.C.T. Whilst specific to and based on work of the Commission and the Department of Housing and Construction in the A.C.T. region, much of the approach and data has a wider application. Prices range from $17.50 for the looseleaf issue of 'Guidelines' to be updated periodically to $3.00 for Technical Paper No . 29 .

EDITOR 21

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