have you checked your plenum space lately??? · pdf filewouldn’t it be nice instrumental...

June 2010

HAVE YOU CHECKED YOUR PLENUM SPACE LATELY???

WATERWORKS JUNE 2010 3

In early February this year I visited Chris

Laidlow and Jason Colton in Wellington

New Zealand. Chris is the Water Supply

Manager for Greater Wellington Regional

Council (GWRC) and Jason is the director

of h2ope, a small NZ company specialising

in process engineering for the water

industry. I was aware that Jason and Chris

had developed a feed forward coagulant

dosing control system for both turbidity and

organics (dissolved organic carbon) removal

in water treatment.

The Com::pass system as it is called, is

based on data collected by an S::CAN

Spectrolyser (Figure 1), an instrument that

continually measures the UV Vis absorption

spectrum of water. The Com::pass system

completely controls the dosing of coagulant

at the Wainuoimata WTP in response to

changes in raw water turbidity and organic

content. The plant was originally

commissioned in 1995 using a streaming

current meter (SCM) to control the

coagulant dose. Com::pass was installed just

under four years ago and the plant has run

using this control system since then.

Com::pass has also been used on another of

the GWRC plants for the last two years.

Figure 1. The spectrolyser that collects the

data is indicated by an arrow.

Excellent coagulation requires fine control

of pH. For this reason coagulation pH is

monitored using three pH meters (Figure 2).

Figure 2. Coagulation pH is critical forgood coagulation and flocculation. Here3 pH meters provide “triple validated”pH control of the coagulant pH. This typeof monitoring while very rare in Australiais quite common in the UK and continent.

GWRC have also developed an impressivearray of operations monthly reports basedon their SCADA system. As well as the usualprimary measures of turbidity, chlorineresidual, and pH they have developed arange of secondary or derived trends. Theseinclude unit costs of production based onchemical costs and power costs. They havecollected sufficient data over the years to beable to predict the costs of production basedon the raw water quality as measured by theSpectrolyser. The information is so wellestablished that they have been able to alarmtreatment costs. If the costs are increasing,an alarm is activated and operators arealerted to the fact that the cost is increasingbeyond the maximum allowable and theyshould identify the cause. As they have thesesensors in each raw water source they utilise,they know the unit costs of production fromtheir alternative raw water sources and willalter ratio’s of water drawn from each sourceor shut down one source and activateanother based on their SCADA monitoring

Monthly reports include time seriesgraphs of turbidity for individual filters andchlorine residuals. Frequency graphs areprovided for both 3 minute and 30 minutechlorine. These graphs make it immediatelyapparent how well the filters have beenperforming against the target objective of0.1 NTU and whether the disinfectionsystem has worked reliably for the month orwhether there have been periods of low orpoor chlorine dosing. This reporting iseffectively compulsory because theDepartment of Health in New Zealand has

Editorial Committee

Peter Mosse, Editor

[email protected]

George Wall

[email protected]

Direct mail to:

Peter Mosse

WaterWorks Editor

c/-WIOA, 22 Wyndham Street

Shepparton Vic 3630

Advertising & ProductionHallmark Editions

PO Box 84, Hampton, Vic 3188

99 Bay Street, Brighton, Vic 3186

Tel (03) 8534 5000 Fax (03) 9530 8911

Email: [email protected]

WaterWorks is the publication of the Water Industry

Operators Association of Australia (WIOA). It is

published twice yearly and distributed with Water

Journal. Neither the WIOA nor the AWA assume

responsibility for opinions or statements of facts

expressed by contributors or advertisers. All material

in WaterWorks is copyright and should not be

published wholly or in part without the written

permission of the Editor.

Contributions WantedWaterWorks welcomes the submission of articles

relating to any operations area associated with the

water industry. Articles can include brief accounts

of one-off experiences or longer articles describing

detailed studies or events. These can be emailed to

a member of the editorial committee or mailed to

the above address in handwritten, typed or printed

form.

CONTENTS

Editorial 3

INTERVIEW: Dave Barry of Aqualift 4

Pipes, Materials and Failures 6

Water Safety vs Occupational Safety 12

Measuring pH Problems Overcome 15

Filter Head Loss Profiles 16

Lessons for Operators: Victorian Safe

Drinking Water Act Audits 18

E D I T O R I A L

WOULDN’T IT BE NICEINSTRUMENTAL CONTROL AND HIGH

LEVEL OPERATIONAL REPORTINGPeter Mosse

OUR COVER

An artistic shot showing sand in the plenumspace. A pretty photograph but not a prettysight for the operators of the filters.

Continued over page

4 WATERWORKS JUNE 2010

How did you get started in reservoircleaning?

It was just another job really. BradGannon from Beaudesert ShireCouncil was cleaning his pool oneSunday morning and wondered if itwas possible to vacuum out a tank.Their tanks were stand alone, so anycleaning involved a complete shutdown and no water for the residents.That’s generally when a fire happensas well, so any way of doing it onlinewas attractive.

Brad gave me a call, we visited thelocal pool shop, bought some pool typecleaning gear and gave it a go. The trialwent OK, but it was slow due to the sizeand type of the plastic vacuum head. Hesuggested a price that they could clean atank manually for and said I had the job ifI matched it…. then it became a challenge!

I went away for about six months andthought about it, on and off, found theideal SS vacuum head in WA (where theyused such things for vacuuming out theponds in crocodile farms), thought thatusing a dry suit may seem attractive to theconsumers who had to drink the waterafterwards and then basically flipped a coinas to whether I would gamble aboutoutlaying $8000.00 in equipment costs to

earn $2500.00 - that’s what made it all soattractive!!

Then a continuing string of luck camealong that got it over the line, so I cannotclaim much credit for it in the end.

Optus (sorry Telstra, but you missed outhere!) gave me three serious paying divejobs, laying cables in Northern NSW rivers– that solved the cash flow issues.

Once you got the idea, how did you get intothe Water Industry and get it accepted?

We cleaned the two Beaudesert tanks, tooksome good photos, and then Brad gave apaper on the process at a WITA conferencein Hervey Bay and won Operator of theYear award…..we were up and running!His boss then gave the same paper at an

AWA conference in Stanthorpe and wewere sprinting, not running!

The Queensland Department ofPrimary Industries got in on the act andmade a movie about it which became abest seller. I think their movies to datehad only sold about 20 copies each,being about bacterial slime and otherattractive titles, but I bought around300 of this one and sent it out to everyCouncil listed in Yellow Pages that Icould find. Slowly we got all the hardand impossible tanks to clean aroundthe country - in two years we had

cleaned a hundred tanks and thought weknew it all!!

What was your biggest success?

There are two successes that come to mind– one of a practical nature and the othermore of an achievement for our process.After cleaning about ten tanks, with thediver standing in one spot at a time andpushing the vacuum head around on a longhandle (remember we were underwater poolcleaners then!)… the handle broke off!! Ithought...”now we are in trouble, but I willpush it along using the handle stub tofinish the job”. We found out we couldtravel around four times faster and easier –so if innovation can come out of adversity,this was the BIG ONE!

As for the achievement one: we wereworking away in a small country town oneSunday morning, minding our ownbusiness, when this guy, dressed for golf,strode up and confronted us…”What areyou blokes up to?” “Not stealing water areyou?” So I told him we were vacuumingout the tanks around the place and givingthem a thorough inspection for waterquality issues and everything else we couldthink of at the time. “Any way, who areyou?” “I’m the Mayor he said, I live justdown the road, and people have beenstealing water around these parts lately”.Then he asked what the condition of thetanks were like, seeing as he was drinkingthe stuff himself. So...I told him – “a bitlike in a third World country” andproceeded to show him the swallows flyingin and out of the tank and the security gatehanging off its hinges and all the otherthings that were pretty obvious (to usanyway)! He was late for golf, but didmention he would talk to the GeneralManager about it on Monday. I told the

strict requirements for the performanceof these filtration and disinfection controlpoints and clear limits that constitute atransgression. For example, for plantsclaiming the highest level of protozoanmanagement, the water from individualfilters must have a turbidity of <0.1 NTU95% of time, <0.3 NTU 99% time andmust not exceed 0.5 NTU for any 3minute period. For treatment plantsclaiming lower log removal of protozoanpathogens, the requirements are slightlyless demanding although the targetturbidity is still very low at 0.15 NTU.

Since a restructure of the CouncilWater Supply division in1997, GWRChave been able to substantially reduceoperational costs and part of this hasinvolved the Com::pass system. Thesecosts have not even paralleled the CPIincreases over the last 10 years. The

restructure did not include cutting staffand there has been no reduction inservice levels. They have also improvedtheir Ministry of Health ratings overthis period. Pretty impressive really!Made me think isn’t this what all watertreatment operations should be like. It’snot hard, it just requires commitment towhat we are about i.e. producing safedrinking water. But interestinglyGWRC has been able to demonstratevery large savings doing it.

So the Kiwis have thrown down thegauntlet. Jason and Chris are aformidable team but there is no reasonwe cannot do this in Australia also.

I am sure that Jason and Chris wouldwelcome anyone from Australia seriouslywishing to move their water utility alongthe same lines. Contact WIOA if youwould like to follow this up.

I N T E R V I E W

Editorial continued from previous page

INTERVIEW: DAVE BARRY OF AQUALIFT


boys that I thought the ‘messengerwould be shot for this one’, and thiswould be our last time working in theMayors town and surrounding area!Two months later we received a callfrom the water supervisor asking if wecould assist them in fixingEVERYTHING listed in our reports! Allour reports had been tabled in Council,put on their web site, and they had$70K a year to spend for however long ittook to fix everything! All due to theMayor being late for golf (and usworking on a Sunday). I haven’t met aMayor since, but we still work on Sundays and live in hope!

Then Sydney Water finally returned my constant phone callsand passed me onto Max Harry. Max used to handle all the crankcalls apparently! He arranged a meeting with some of his corporateclients and told me I had 20 minutes to make or break. So…Ibrought along $30.00 worth of chocolate biscuits, and it was a‘done deal’. Oh, they must have liked the talk as well, because wewere in the door with the big guys and have never really lookedback. Sydney Water also had a video production unit, so anothermovie was made, hundreds of copies were bought and sent out,this time into Victoria, SA and WA – there was no turning backfrom that point on.

What has been your worst job?

We have found lots of pretty ordinary things in tanks to date, butthe dead dog sort of sticks with me. It was floating on the surface,around 4 to 6 weeks old, so I decided to get it out somehow.Wrapped it in a tarp, got my shoulder under it and carried it upthe ladder. That was OK, because I still had my full face mask onand couldn’t smell anything. The guys up the top who werehelping (and vomiting at the same time) should have been a ‘giveaway’. When I lifted my mask off, (which was covered in ‘dogbits’), I just about dropped back down the ladder!

The local supervisor told me later (after the tank was drainedand sterilized), that he thought his wife had bought a new brand ofcoffee, because his morning cuppa had tasted a bit different for thelast week! ‘Hair of the dog’ took on a whole new meaning!!

What has been your philosophy as you have developed the business?

This probably defies all those ‘self help’ and management booksout there, but I have just continued to ‘make it up as I wentalong’. I have never been in a hurry to make a profit out of it all,but rather to make life easier out on the job. Better equipment andmore resources (which makes you sleep better at night, knowingthings are backed up and equipment is duplicated).

Over the years I have had some great mentors and also manygreat employees who have not been afraid to put in their ideas. Myjob has just been to make it all work out and to keep on tryingnew things. I have a shed full of failed equipment and a memoryfull of things that were pretty stupid in hindsight, but we alsocame up with some classics along the way. We began using KYlube on our dry suit seals way before it was acceptedpractice…..and don’t ask me where THAT idea came from! But itis tax deductable and not everyone has a plausible excuse to carryaround over 40 tubes of the stuff in the truck at any one time!

What are your thoughts on how we can raise awareness in the OZwater industry, of the poor state of storages and what needs to be done?

Any one reading this magazine has contributed for a start.Education, through formal training, attending conferences and in-house seminars are all good. Many of us know an awful lot about

one little thing, and not much about theother co-dependant things. It isimportant to learn as much as possibleabout not just our own field ofinfluence, but how it can effect (andenhance) other related subjects.

But there is one thing that noteveryone seems to be comfortable with,and that is ‘asking the hard questions’.Unless more people continue to ask thehard questions, we will remaincomplacent and continue to ‘do things asthey have always been done”. This isoften to avoid offending another person

or upsetting an established process, but everyone who holds a jobin this industry has an obligation to ‘do the best for the Industry’and not what is sometimes best for themselves.

Where to in the future for Dave Barry and Aqualift?

Don’t give up, keep on going till one of my guys does the decentthing and ‘puts me down’ (painlessly I hope). Continue to ask thehard questions, mentor the younger generation in return for thementoring I received over the years and finally to continue toexpand Aqualift, not in a financial sense, but rather in a way toremain relevant within the industry as it grows and changes.

In seventeen years, it is less about diving and more about ‘problemidentified, solution supplied’. That little mission statement hit methe other day and I thought …“that’s nailed it”…but the acronymleaves a bit to be desired hey??

I N T E R V I E W


Pipes in the Australian Water Industry areestimated to have a replacement cost of around$35 billion and the fact is that many arereaching the end of their useable life. The totallength of pipelines in use in Australia has beenestimated at more than 139,000 kilometres.Figure 1 shows the typical lengths of pipe laideach year between 1875 and 2002. Mostdevelopment occurred between the mid 1950sand the mid 1970s where large numbers ofpipes were laid to accommodate the majorexpansion of population in the major citiesfuelled by immigration and post World War IIdevelopment.

Due to the ravages of corrosion, many pipeshave already been replaced with alternative“non-corroding” materials, but corrosion ofsome traditional pipe materials is an ongoingissue for all water agencies.

Figure 2 shows the types of pipes of differentmaterials for one large Australian water utility.However pipeline material do vary betweenwater utilities. This is primarily due to waterquality. Asbestos Cement (AC) pipes were notgenerally used where water was soft, such as inMelbourne or Sydney. In these systems the ACcomponent was replaced by grey cast andductile cast iron pipes which therefore make upthe largest percentage of pipes in these waterreticulation systems.

Pipes and Pipeline Failures

Pipes don’t last forever and pipeline failures area fact of life for water utilities. Figure 3 showsthe number of pipeline breaks per 100km for anumber of Australian capital city water utilities.The graph clearly shows the significantdifferences between utilities.

Nationally, the average rate of breaks of allmajor water agencies is 28 per 100km. Thismeans that for the 139,000km of mains in2007/2008 there were a staggering 38,900breaks. This equates to one every 13.5 minutes.

In the past, pipelines were run to failure, thepoint at which the number of failures in a pipebecomes unacceptable. While this is still often

W A T E R P I P E S

PIPES, MATERIALS AND FAILURESGreg Moore

Figure 1. Lengths of pipe laid by one large Australian water utility each yearbetween 1875 and 2002.

Figure 2 Lengths of different pipe types for one large Australian water utility.

the case for small mains, for large mainsthere is now greater emphasis onundertaking pipeline conditionassessment to predict failures and toreplace the pipeline before any failureshave occurred.

Metal Pipes

Cast Iron Pipes

Cast iron pipes are the most commontype of pipes in most distributionsystems. Cast iron pipes were the first

metal pipes used for water supply. Theearliest cast iron pipes were produced inEurope and all of the early cast iron pipesused in Australia were imported. In the late1800’s, many foundries started to produce

cast iron pipes in Australia. These weresupplied to local markets and in theabsence of any standards, were often madeto local requirements. It was not until1903 that cast iron pipes were standardised

in the UK. Typically the pipes were thickwalled grey cast iron with an internal liningand external coating of Trinidad tar orbitumen. The internal and externalcoatings served as corrosion barriers. Thedeficiencies of this basic corrosionprotection soon showed up internallywhere the coating broke down resulting inextensive internal corrosion (Figure 1).Many of these pipes in Australia were thencement lined in situ. This overcame themajority of the internal corrosion problem.Cement mortar lining has proven to be avery effective lining for prevention ofinternal corrosion. The cement layerprovides both a physical barrier to thewater and also provides a high pHenvironment at the cast iron surface.External corrosion is by far the mostprevalent form of failure of cast iron pipe(Figure 2) due mainly to corrosive soils.The thick walls of the early cast iron pipesmade some allowance for this externalcorrosion. Some of these pipes with onlythe original bitumen external coating arestill in use today after 100+ years of servicebut generally only in areas of low soilcorrosivity. The earliest cast iron pipes

W A T E R P I P E S

Figure 3. Watermain breaks per 100 km for mains in 2007–2008.


were manufactured in sand moulds. As a

result of the manufacturing process, a layer

of silica formed on the surface of the pipe.

This layer provided some protection against

corrosion. With the introduction of spun

cast iron pipes in 1929 produced in a steel

mould, the silica layer was not formed. The

new process allowed the formation of pipes

with a thinner wall but without the

protective silica layer. As a result these pipes

were in some ways more prone to corrosion

than the pipes produced using the original

methods.

Figure 1. Internal Corrosion of an

unlined cast iron pipe.

Figure 2. External Corrosion of a cast

iron pipe.

Steel Pipes

Steel pipe was first introduced in Australia

in 1885. It was sometimes incorrectly

referred to as wrought iron pipe. At this

time, welding of steel had not been

invented so the steel pipes were either

riveted (Figure 3) or joined using an

innovative locking technique using

longitudinal bars (Figure 4). Not

surprisingly this Australian invention was

known as locking bar pipe and was used

extensively from 1895 – 1925. The most

famous pipeline constructed using this pipe

was the Perth to Coolgardie pipe line. The

pipeline was constructed in 1898 – 1902and was 560 km long. However like theearly cast iron pipes, both internal andexternal corrosion protection was limited toeither a tar or bitumen coating.

Figure 3. Riveted steel pipe.

Figure 4. Cross section of locking barjoint. The two edges of the pipe barrelare formed into a dovetail shape whichfits into a grooved metal bar which isthen rolled down over the dovetailedends to lock the the pipe together.

These pipes were usually larger diameterand in most cases were lined in situ with acement mortar lining that overcame theinternal corrosion issues. External corrosionprotection was provided by a layer ofhessian reinforced coal tar or bitumen.Inevitably this failed.

The different mechanical properties ofthe steel compared to cast iron generallyresulted in the formation of leaks which inmany cases could be effectively repaired.This was in contrast to grey cast iron pipethat generally fails catastrophically.

More Recent Metal Pipes

Ductile Iron (DI)

Ductile cast iron pipes were first introducedinto Australia in 1973. The mechanicalproperties of this material with highertensile strength and ductility compared togrey cast iron meant that the wall thicknesswas able to be reduced for equivalentpressure ratings. It was recognised thatexternal corrosion prevention requiredenhancement and at this time the use ofloose fit polyethylene sleeve became morewide spread to provide protection. Thistechnique has in most cases provided verygood performance but like all techniqueshas its limitations. Where problems havebeen experienced, these have been related to

W A T E R P I P E S


W A T E R P I P E S

galvanic corrosion of the ductile iron due tothe use of un-insulated copper waterservices, poor installation or being used insituations where this form of protection isinappropriate, for example anaerobic salineground conditions. Internal corrosionprotection is provided by a cement mortarlining (DICL). The lining is added at thetime of manufacture resulting in a densehigh quality lining with excellent resistanceto corrosion.

Steel

While steel has been used for over 100years, today’s steel pipe has had manyimprovements in corrosion protectionresulting in a high performance product.Fully welded steel pipe externally coatedwith fusion bonded polyethylene andcentrifugally lined with cement mortarlining can provide a 100 year life demandedby the industry. Some manufacturers haverecently promoted epoxy or other organiclinings as an alternative to cement mortarlining but these are unlikely to provide thelong term performance required by theWater Industry. Prior to the introductionof fusion bonded polyethylene external

coatings, coatings of reinforced coal tarenamel were widely used. While thisprovided improvements over the very earlytar and bitumen coatings it was susceptibleto deterioration, particularly due to soilstresses which resulted in splitting of thecoatings and subsequent exposure of thesteel to soil corrosion (Figure 5).

Figure 5. Splitting of coal tar enamelexternal coating due to soil stress.

External corrosion of steel pipes is alsothe major cause of pipeline failure; howeverwelded steel pipes and their jointingtechnology are also suitable to theapplication of cathodic protection (CP).This has allowed CP to be retrofitted to

these pipes and has been very successful inextending the life of these pipes. The use ofCP has not been effective on the very earlysteel pipes which were lead jointed. Thelead created high resistance joints andprevented sufficient electrical continuity.

Non Metal Pipes

Wood

Figure 6. Construction of an early woodstave pipe.

The first pipes used in ancient times weremade of clay or wood and are only ofhistorical interest as none of these are incurrent use. Some pipes used in Australiawere however of wood construction knownas wood stave pipes where slats of timber


were fashioned into a pipe, not unlike awine barrel but continuous in nature(Figure 6). These wood stave pipes wereused by many water agencies but theygenerally only provided a short life due tointernal rotting of the timber. Steelreinforced concrete pipes were also used bysome agencies but these were generallyrelatively low pressure and were not widelyadopted by the major water agencies.

Asbestos Cement (AC)

The first AC pipes were manufactured in1916 in Italy. Manufacture commenced inAustralia in 1926 and continued up until1986 when manufacture ceased due to thehealth and safety issues associated with useof asbestos. AC pipes were one of the firstcomposite pipes being composed ofapproximately 10-15% asbestos fibres in amatrix of Portland cement. Some also had asmall amount of finely ground silica added.AC pipes were used extensively in Australiaexcept where the water was soft with a lowpH. However in some situations, bitumencoating of the AC was available to provideadditional protection in situations wherethere was soft or aggressive water. In harderwater, AC pipes were promoted as havingexceptionally long life and as such, largequantities were used. In some utilities ACpipe makes up more than 50% of pipelineassets.

AC pipes do not corrode in the way thatsteel and cast iron pipes rust, but instead itundergoes chemical conversion of thecement binder. There is often nodiscernable change to the dimensions as aresult of this change, but the loss of binderor its replacement by a weaker productforms a weak material that when damp hasmechanical properties that have been called(unfavourably) by water maintenanceservicemen as wet cardboard.

Originally it was thought that AC pipeswould not corrode and life expectancies ofthe order of 80-100 years were regularlyquoted. This was found not to be the casewhere the pipes were buried in aggressivesoils or where they conveyed aggressivewater.

AC pipe deterioration can occur at boththe internal and external surfaces of a pipe.The resulting loss of strength begins tocompromise the structural integrity of thepipe making it progressively moresusceptible to failure due to internalpressure loads.

The common method used to assess thedepth of deterioration or degradation of anAC pipe wall is by staining withphenolphthalein indicator. Phenolphthaleinis a weak acid indicator that changes to aprogressively deeper magenta colour from apH of 8.3 to 10.0. This colour change canbe used to highlight the difference betweenthe alkaline areas where the cement matrixis sound and the lower pH areas where theCa(OH)2 has been leached away (Figure 7).

Figure 7. Cross section of AC pipeshowing internal and externaldeterioration. Undeteriorated portions ofAC are coloured magenta (CourtesyOpus International Consultants).

Plastic Pipes

In smaller sizes these pipe materials are alsomore economical than traditional metallicpipes. As such the industry has seen rapidgrowth in the use of these materials.

The two most common types of materialused in Australia are Polyvinyl Chloride(PVC) and Polyethylene (PE). They aregenerally cheaper than traditional metalpipes and don’t corrode in the traditionalsense. However plastic pipes have their ownlimitations and can fail for reasons notrelated to corrosion. While the failure ratesof plastic pipes are generally much lowerthan other traditional pipe materials, there

is often considerable focus on plastic

pipeline failures and subsequent concerns

about their long term performance.

Plastic pipes are made of a visco elastic

material. This means that when the

material is placed under constant stress, the

material creeps and in the long term the

stresses required to cause a pressure rupture

are less than those when the pressure was

initially applied. This change in the rupture

stresses can be related to ageing effects such

as heat or UV, but in a buried pipe these

effects are not relevant and changes to the

rupture stress will occur very slowly under

constant stress. All plastic pipe standards

use a figure of 50 years to determine the

design wall thickness of the pipes to

account for visco elastic creep. This has

created a lot of confusion in the industry as

this has regularly been interpreted as the

pipes only have a design life of 50 years,

after which they will start to fail. This

assumption is incorrect. There are high

expectations on the long term performance

of these plastic pipes and there are many

examples of this but also some examples of

plastic pipe failure. Plastic pipeline failure

can be complex but the fundamental cause

is its resistance to slow crack growth and

subsequent rapid crack propagation

resulting in brittle cracking (Figure 8). It is

these aspects along with a desire to reduce

the amount of material in the pipe that

have driven the development of different

PVC and PE materials with ever increasing

resistance to slow crack growth.

Figure 8. A longitudinal crack in a PVC-

U sewer pressure main.

W A T E R P I P E S


Polyvinyl Chloride (PVC)

PVC pipes were first produced in Germanyin 1934 but it took until 1960’s formanufacture to start in Australia. Thismaterial was used widely in the rural andirrigation industries but it wasn’t until the1980’s that major water agencies inAustralia started to use this material forpressure pipes. The original PVC materialwas more correctly known as uplasticisedPVC or PVC-U. In the last 10 yearsvariations of the PVC have becomeavailable and include modified PVC (PVC-M) and molecular oriented PVC (PVC-O).Both these materials have improvedphysical properties compared to theoriginal PVC-U. This has allowed theplastic pipe industry to produce pipes withlower wall thickness for equivalent pressureratings (Figure 9) and improved resistanceto slow crack growth. PVC pipes forpressure applications are joined by rubberring joints and these generally haveprovided a good leak free service life.

Figure 9. Different types of PVC havedifferent wall thickness for equivalentsize and pressure ratings.

Polyethylene (PE)

Polyethylene pipes were first used in theearly 1950’s in Europe and the USA. Somepipe was produced in Australia in the late1950’s but it wasn’t until the 1960’s whenit started to be produced more widely.Since its introduction there have beensignificant changes to the polyethyleneresins. Early PE material was classified asPE 32 which meant it had a long termminimum required strength of 3.2MPa.The standard material that is produced andused by the water industry today is PE100with a long term minimum strength of10MPa. These significant changes to thestrength have also resulted in a productwhich has very high resistance to slow crackgrowth. This makes it an ideal material forpipeline renovation. The PE is pulledthrough existing pipe materials without theneed to fully dig up or create a new trench.PE pipe can also be produced in longlengths with minimal joints all of whichcan also help to provide a long service life.Current generation PE pipe has excellentresistance to slow crack growth and failuresof the type shown in Figure 10 are rare.One draw back with PE as a pipe material

is its need to be welded. While this also hassome benefits in terms of the pipelinedesign, the welding process requiresconsiderable quality control and experienceto produce good welds. To date, jointfailure in PE pipe systems is the area wheremost problems have occurred. A number ofwater agencies are now specifying PE for allapplications and the challenges for thesewater agencies will be to introduceappropriate requirements for qualitycontrol of joint welding.

Figure 10. Slow crack growth in PE pipematerial.

Other Plastics (ABS, Glass ReinforcedPlastic (GRP))

Glass reinforced plastic pipes, also oftenreferred to as fibreglass pipes are used inlimited applications where high corrosion

resistance is required, particularly in thelarger pipe diameters. These have foundmore favour in the chemical industry andin seawater applications and with fewexceptions have not been used in manywater reticulation schemes. SimilarlyAcrylonitrile Butadiene Styrene (ABS) hasnot generally been used as a mainstreamwater reticulation pipeline but is widelyused for process pipework in water andwastewater treatment plants.

Acknowledgments

WIOA would like to thank Wesley Fawazof the Australian Corrosion Association forpermission to reproduce an extract of apreviously published article by GregMoore.

The Author

Greg Moore ([email protected])is the Principal of Moore MaterialsTechnology Pty Ltd in Adelaide. Hespecialises in failure analysis of plastic andother non ferrous pipes, assessment ofprotective coatings, soil corrosivity,corrosion of stainless steels and othermaterials used in the water and waste waterindustry.

W A T E R P I P E S


Most things in life require a balance. TheWater Industry in Australia is facing aconflict in maintaining an appropriatebalance in the area of occupational safety. Itis something that is very easy to overlookwhile things ‘appear to be functioning’satisfactorily. A lot has been said latelyabout producing safe drinking water, waterthat doesn’t make the customer ill. We havethe Australian Drinking Water Guidelines,Safe Drinking Water Regulations and othermanagement systems to provide guidanceand direction. There are processes andtechnologies in place and a substantialinfrastructure to deliver safe drinking waterto our consumers. But is it enough?

To operate this infrastructure, we requirepersonnel who can carry out their rolessafely and with confidence. Without OHS,personnel working in the many diversefields that make up the water industrywould be placed at risk, and the watersupply utilities could be subject to verysubstantial legal liabilities.

But this is where the balance becomes‘blurred’. OHS only extends to thepersonnel involved in the production anddistribution of water. OHS and itssignificant penalties for non-compliancehave stopped short of managing the healthand safety of the consumers. This is ashame when you consider the advancesmade to the safety of our work force in thelast generation.

In an OHS situation, a ‘nearmiss’ report will lead to acoordinated effort to examine,analyze and correct thesituation. This is because thereporting mechanisms are verysimple and can be instigated byany member of staff notifyingthe Health and Safety officer ofunsafe practices. Indeedmembers of the general publiccan pick up the phone and callWork Cover.

In contrast, the protectionsput in place to look after thewater consumers are verypoor, in terms of legislativerequirements andenforcements. How simple is it

to report a ‘near miss’ in a water qualitysituation? The evidence is not alwaysobvious to the general public or to thenaked eye without scientific testing.Auditing of records and extensive followup is often required before an incidentcan be identified and appropriate actiontaken.

The process required to instigate anaction is far harder and therefore likely tobe ignored, unless something of acatastrophic nature occurs.

All of the above is leading up to a veryimportant point. Some OHS practices areplacing water quality at risk on a dailybasis. There are many examples of operatorsbeing restricted from carrying out necessaryprocedures in the name of OHS, withoutalternatives being given, to allow these

necessary procedures to be carried out asrequired. We will provide two examples.

Treated Water Storages

Elevated storage tanks (Figure 1) are a goodexample of neglect. OHS departmentsrestrict access to these structures. Mostpersonnel are not comfortable or competentto climb anything more than a basic, lowladder system. Consequently high,restricted areas are often left unattended orunchecked. Without checking, waterutilities do not really know what ishappening to the water in these storages.Somehow the restrictions placed by OHSmust be replaced by a system to allowregular inspection and correction of anyproblems. Ignoring this requirement putsmany members of the public at riskcompared with one or two utility staff. Twocase studies are presented here and the factthat these cases are typical is rather scary foranyone consuming water from adistribution system.

Case 1

An elevated tank supplying a town of over2000 was deemed unsafe to climb by thewater utility OHS department as part of ageneral audit done on similar types oftanks. This tank design relies on roofmounted drains to prevent storm waterfrom collecting and draining back into theaccess hatches. The situation was further

complicated by significant birdactivity and large amounts offaeces that had collected on theroof area (Figure 2). When thetank was finally accessed safelyby trained personnel, a thick,smelly, green, soupy materialwas found to be drainingdirectly into the stored water(Figure 3). This mixture of dirt,bird faeces and storm water hadblocked the roof drains due to alack of regular inspections andmaintenance! The irony of thistank was that the internalladders had been designed tomeet AS1657-1992 (Fixedplatforms, walkways, stairwaysand ladders) and yet there wasno safe access to the roof andthe hatches.

O H S v s S A F E D R I N K I N G W A T E R

Figure 1. One of the elevated storages.

Figure 2. The access hatchway surrounded by piles of birddroppings.

WATER SAFETY vsOCCUPATIONAL SAFETY

Dave Barry and Peter Mosse


Case 2

An elevated tank situated inside the maindepot of a water utility where at least 50personnel were had been left unattendeddue to OHS restrictions. It was an obvioushabitat for pigeons that were frequentlyobserved flying around and roosting on thetank. This bird activity led to anaccumulation of faeces across the roof andaround the entry hatch area, due to a lackof regular maintenance. When the hatchwas opened, the surface of the water wascovered in feathers (Figure 4) that hadblown into the tank past the unsealed entryhatch frame.

The importance of preventing entry ofbird faeces to treated water storages isprovided by the case of a waterborne diseaseoutbreak in Gideon Missouri in 1993. In anattempt to address customer complaintsrelating to the taste and odour of the water,the local council undertook an extensiveflushing program to clean out the system.This led to a rapid turnover of water fromthe municipal storage tanks. Shortly afterthis, people in the town started to becomeill. The end result was that of a populationof 1100 people, 600 became ill and 7 died!Sediment from the tank was found to becontaminated with Salmonella. Inspectionof the tank revealed a bird roosting site overthe roof of the tank, bird droppings on theroof and feathers on the surface of thewater, pretty much what you can see inFigures 2 and 4.

Clearly those towns in the case studiesabove are at a high risk of seeing Gideonrepeated in them.

To protect public health, a balance isrequired between allowing access andinspection and protecting the worker.

Media Filters

Media filters (sand and filter coal) are theonly barrier to the pathogens Giardia andCryptosporidium in a conventional watertreatment system. Many people erroneouslythink that as long as the chlorine system isworking, everything is fine. The problem isthat chlorine does not kill Cryptosporidiumor Giardia at the levels we can use in thewater industry. So if the filter doesn’t takethem out, the chlorine won’t touch themand they will be free to pass out into thedistribution and possibly into someone’sglass of water.

Let’s consider some figures. In an analysisof 61 published reports of waterbornedisease outbreaks, Risebro et al (2007)found that:

• 41 were due to more than 1 cause

• 34/61 were due to two events notablysource water contamination and treatmentsystem failures occurring together

• 23/61 were due to contamination ofdrinking water with protozoa where therehad been a failure of treatment

• 90% of the identified failures oftreatment were filter failures, many ofwhich were chronic failures.

An important part of ensuring that mediafilters are operating correctly is to inspectthe filter bed inside the filter cell. Thisshould be carried out at least once per year.But once again many OHS departments inwater utilities are making it increasinglydifficult for operators to enter filters tocarry out these inspections. Some allowentries but only if the treatment plant isshut down. Unfortunately the plant needsto be running to allow full criticalobservation of backwashes and theninspection of the media.


Figure 7. A fully enclosed filter. Actualentry to the filter would require fullconsideration of confined space entryhowever simple inspection of the surfaceof the media is simple and safe.

Figure 5. A filter with a relatively highrisk of injury during entry. Fall arrestwould be appropriate here.

Figure 6. A safe easy filter to enter. Fallarrest would not be necessary here.

Figure 3. Ponded green water with easy access to the hatches. Figure 4. Feathers on the surface of the water. Clear proof ofcontamination.

There is no single procedure for entry toa filter since they are all quite different(Figures 5 and 6) but all open filters can beentered quite safely. Mosse and Murray(2009) provide an example risk assessmentand generic filter entry procedure. This canbe taken as a basis for site specific entryprocedures to be developed. Enclosed filterssuch as the one shown in Figure 7 do posesome difficulties but inspections are alwayspossible.

The major issue with filters is to ensureaccess is made as safe as possible. Thehighest risk is climbing over a rail where no“gateway is provided. Simple gate systemscan be easily retrofitted or included at thetime of construction (Figures 8 and 9).

Again, to protect public health, a balanceis required between allowing access andinspection and protecting the worker.

Conclusions

At present the formal aspects of OHS aspracticed in the water industry are aimed atprotecting the worker and rightly so. BUTthey are not similarly aimed at protectingconsumers from debilitatinggastrointestinal illness. WRONG. Thebalance is just not right. The imbalanceneeds to be addressed urgently if we are toavoid an event such as Gideon, Missouri ora Galway Ireland where out of a populationof 72,000, 250 became ill or Milwaukeewhere in 1993 over 400,000 became illwith Cryptosporidiosis and over 100 died.

In the words of an old folk song “whenwill they ever learn”? All we can do is try to

draw attention to the problems. Those ofyou in the water industry withresponsibilities take over from there. If youneed some incentive, think about how youwould feel if you found yourself in theposition of watching an event like GideonMissouri unfold in a town or city you haveresponsibility for. This and the photos weinclude above are the reality. In the wordsof Steve Hrudey

“If after reading about all of the otherfactors that have gone wrong to causeoutbreaks in 15 different affluent nationsyou are truly certain that none of this couldever happen to you, then congratulations.To be justified in being certain, you mustknow your system very well and you mustunderstand all of the ways that things cango wrong. You must have effective andwell-practiced plans in place for dealingwith the many problems, large and small,

that can happen if you are to be truly

confident about avoiding a Walkerton style

disaster. However we suspect that those of

you most likely to avoid encountering such

problems will be those who are willing to

believe that Walkerton style problems

could happen. The choice seems clear:

unwarranted peace of mind or nervous

confidence underlying the vigilance

necessary to forestall appearance before a

Walkerton like Inquiry.”

References

Hrudey, S.E. and Hrudey, E.J. (2004). Safedrinking water. Lessons from recent outbreaksin Affluent Nations. IWA. London

Mosse, P and Murray, B.(2009). Practical guideto the operation and optimization of mediafilters. WIOA Shepparton.

Risebro H.L. et al (2007). Fault tree analysis ofthe cause of waterborne outbreaks. Journal ofWater and Health.


Figure 8. A simple “trombone slide” entry gateway has been cut in the rails surrounding a filter

Figure 9. A purpose built filter accesspoint.


The problem arose when I receivednotification of a high aluminiumresidual in a routine reticulation systemsample. This was not what I wanted tosee and of course I had to question thetest result.

My reason for this was that I ran theplant at a coagulation pH of 6.0, whichis the pH I understand to be the pointof least solubility of aluminium into thewater. My online pH meter was tellingme that this pH was indeed 6.0 +/- 0.2.I trusted the online instrument, as itwas not very old, routinely calibratedand kept clean. I decided to check asample of the coagulated water with myportable pH meter, which again isroutinely calibrated and kept clean. For therecord I use Schott full glass probes on theportable meters. The check with theportable unit came back with a pH ofaround 5.3. My immediate reaction was toclean and recalibrate the portable unit butalas the same reading resulted.

What to do?

I still had one of the old comparatorsand so decided to use it to do anothercheck. Admittedly the reagents arelike me getting a bit long in thetooth, but still indicated a reading inthe same 5.3 area using Bromo CresolPurple reagent tablets.

This led me to getting in touchwith my instrumentation technicianand asking if he would mind comingin and carrying out another fullcalibration and clean of the onlineinstrument. This he did as well asreplacing the tip and electrolyte.After all this, the same reading ofaround pH 6.0 was obtained. Hethen did a calibration of the portableunit to check my earlier calibrationand checked the water with it. Theresult was again around pH 5.3.

At this time another instrumenttechnician was consulted and histhoughts were that the flow throughthe inline unit was too fast for theprobe to react and so couldn’t give areliable reading. The flow rate wasreduced, and even at a very low flow

the readings were still hit and miss. It wasimportant to be able to keep the flow rateup to keep the loop times close to keepbetter control over the dosing.

The probe was taken out of the inlinefitting and placed in a small bucket whichhad an overflow hole cut in it so as to actlike a reservoir, and the coagulated water

flow was directed into the bucket.This simple change proved to be thesolution. Even at the normal flow rate,the increased area for the water totravel around had the inlineinstrument reading close enough tothe portable unit.

So we set about designing andbuilding what we called a stillingvessel and then installing it in thesystem. The flow rate through thevessel is in the region of 5 L/min andto date the in line coagulation pHinstrument is performing beautifully. Iam lucky to have two portable pHmeters and one of those is also in thevessel and is checked every morning as

a check on the system performance. It isworking well here.

Our vessel is basically a piece of 150mmhigh pressure PVC water pipe 680mm high.The pipe was cut such that a sloping floorcould be plastic welded in place to allow forfast efficient draining to remove the sludgethat builds up in the vessel over time. The

inlet into the vessel is via a 15mmPVC pipe increased to 40mm anddirected to the bottom of the vessel toreduce the velocity but keeping thewater mixing in the vessel to reducedead areas. The outlet / overflow is40mm PVC and is through the walland welded in place. The support tohouse the pH probe is a piece of 6mmthick PVC sheet shaped and weldedinto the pipe at about the centerlineof the overflow. The stilling vessel isshown in Figure 1.

A drawing with pipe dimensions ofthe assembly is shown in Figure 2.

Acknowledgments

Thanks to Duane Kelly for his help indesigning and installing the stillingvessel and to Gippsland Watermanagement for allowing operators totry out “crazy” ideas.

The Author

Wayne Shaw([email protected]) is atreatment plant operator withGippsland Water.

p H T E S T I N G

Figure 1. Stilling vessel.

MEASURING pH PROBLEMSOVERCOME

Wayne Shaw

Figure 2. A “technical drawing” of the stilling vessel.


W A T E R F I L T E R S

Media filters are designed to trap flocparticles left over after the clarificationprocess in the spaces between the grains ofmedia. In rapid gravity filters, the aim is toget penetration of floc into the whole depthof the filter coal layer of a dual media filter.As the spaces become filled, the head lossincreases, the water is held up by theblockage leading to a lower pressure at thebottom of the filter than at the start of therun. (The pressure at the top will remainthe same). Sometimes filter run times areshorter than required. Sometimes this isdue to blinding of the filters at the surfaceor in the first 100 mm or so of the filterbed. In determining the cause of theproblem it is useful to construct a filterhead loss profile. There are a number ofways to do this.

On the odd occasion that SA Water hasbeen faced with the development of headloss problems with its media filters theyhave used the technique described below toidentify the specific portion of the filterthat appeared to be the cause of excessivehead loss. The technique represents apractical method of monitoring thehydraulic gradient of an operating filterduring the course of a filter run.

The technique involves the installationof a number of open-ended tubes to

various depths into the filter bed (Figure

1).

The end of the highest tube should be

immediately below the top of the filter bed,

while the lowest should be as near as

practical to the filter floor. There would

normally be 3 to 5 intermediate tubes, with

some being located just below anytheoretical interface between different filtermedia. The tube bundle can be dug intothe filter bed while it is drained.Alternatively it may be sufficient to lower apre-cut tube assembly as far as the gravellayer during a backwash (when the bed isfully fluidised), and subsequently onlydirectly measure the pressure profile abovethe gravel layer. This would still allow headloss development in the gravel layer to beinferred (as the difference between the totalfilter head loss and the measured head lossat the gravel surface.)

As a filter run proceeds, the water level ineach tube will drop and this drop in levelneeds to be measured. This is best achievedusing a noise emitting water level sensorattached to a tape measure. Such devicesare commercially available (Figure 2).

As a flow is established through the filter,the water level in each tube will drop tobelow the water level in the filter. Thedistance dropped in each tube representsthe pressure drop below the no flowhydraulic gradient at that particular pointin the filter bed. These measurements canbe presented graphically in what is knownas a Michau diagram.

The diagrams below represent twoinstances where SA Water has used thisparticular technique to good effect. Figure

FILTER HEAD LOSS PROFILESPeter Mosse

Figure 1. A set of head loss tubes permanently installed in a filter at Mt PleasantWTP.

Figure 2. Examples of water level measuring equipment (photo supplied byGeotechnical Systems Australia Pty Ltd.


W A T E R F I L T E R S

3 represents the measurements taken at

a new Adelaide metropolitan WTP

some years ago, where it was identified

that the rapid development of excessive

head loss (where the line dives to the

left) was predominantly occurring at

the interface between the anthracite

and sand layers. This indicated that the

filter media chosen was not correctly

matched, and resulted in the media

being replaced.

Figure 4 represents the situation that

developed at a country WTP where

nozzles with very fine slots were used in

dual media filters. These filters initially

operated without problems, but

gradually developed difficulties with

excessive head loss. Filter bed head loss

measurements indicated that this head

loss was developing at the very bottom

of the filter (the line dives to the left

through the gravel and at the bottom of

the filter), indicating that the problem

was with the nozzles. The nozzles were

changed to nozzles with coarser slots.

This change fixed the problem. The

very fine slots of the original nozzles

had become partially blocked by a

combination of biofilm material and

very fine sand particles.

There is another way to prepare a

head loss profile. The asset

management team might not like it but

holes can be drilled through the filter

wall at specific depths and vertical clear

plastic tubes attached to the outside

wall of the filter. In some well designed

plants these head loss profile systems

can be provided for during construction

Figure 5.

Figure 6 shows an example of such

tubes in a pilot plant filter.

The level of the water can easily be

measured using a tape measure and the

head loss profile produced. It is also

interesting to watch the changing levels

as the filter run progresses.

The system described by SA Water is

easy to set up. To really know your

filters, some knowledge of the head loss

profile can be very useful when things

start going wrong. Why not set one up

and try it!

Acknowledgments

The author would like to thank Werner

Mobius of SA Water for information

on the system used by SA Water.

Figure 5. Headloss fittings in the wallof the filter gallery. The flexible tubingis disconnected.

Figure 4. Typical hydraulic gradient resulting from blocking filter nozzles.

Figure 3. Typical hydraulic gradient resulting from high head loss at a filter mediainterface.

Figure 6. Example of flexible head lossprofile tubes fitted directly into a pilotplant filter.


Victoria’s Safe Drinking Water Act 2003(SDWA) requires that state’s waterbusinesses to prepare and implement riskmanagement plans (RMPs) for the drinkingwater supplies they manage. An integralpart of the SDWA is the implementationand independent audit of the RMPs. Theauditors need to be approved by theDepartment of Health.

The first round of audits was held in2008, and a second round was held in2009.

There are important lessons in thefindings of the audits which can help watertreatment operators and other operationalstaff improve the way that they managedrinking water quality.

First Round of Audits

These were undertaken between May andSeptember 2008, covering the period 1stJanuary 2006 to 30th December 2007. Ofthe 25 audits conducted, 15 were found tobe compliant with the requirements of theSDWA, while for the other 10 a numberof non compliances were identified (Figure1).

A summary of the major findings fromthe first audits are presented in Table 1.

Non-compliances were classified ascritical, major and minor, depending onwhether the non compliance was likely tobe a critical, major or minor risk to publichealth. No water business recorded a criticalnon-compliance, and only one waterbusiness was found to have major non-compliances.

Second Round of Audits

In response to 10 audits returning a resultof non-compliance in the first round ofaudits, a second round of audits was heldbetween June and December 2009,covering the period from 1st January 2009to the date of the audit.

This time, 23 of the 25 audits werecompliant. Two returned a non-compliantresult (Figure 2). This was a significantimprovement on the 2008 round of audits,and demonstrated the commitment of waterbusinesses to improve their riskmanagement practices.

The two water businesses that returnednon-compliant audit results had findings ofminor non-compliance. In general, thefindings of minor non-compliance relatedto:

• Not all actions/documentation had beenrecorded as required by the water business’RMP.

• The frequency of recorded results did notagree with the RMP.

The auditors noted a number ofopportunities for improvement. These aresummarised in Table 2.

These opportunities for improvementindicate that there are still issues related tothe implementation of the RMPs.

Implications for Operators

RMPs are not intended to be staticdocuments that reside in the head officeand bear no relationship to the daily workpractices of operational staff. Ideally RMPsshould either reflect or direct the dailyactivities of operational staff.

A significant issue that was identified inboth rounds of audits was that in many

instances the practices that were beingundertaken in the field did not match therequirements or content of the RMP. Thismay indicate that:

• operational staff were unaware of therequirements of the RMP

• the plan did not match the current workpractices in the field

• operational staff were not following therequirements of the RMP.

In the Department’s experience,successful RMPs are developed inconsultation with operational staff. Theplans should reflect the day-to-day activityof operational staff. Quoting a prominentAustralian water quality expert, riskmanagement should not be additional work, itshould be the work.

A RMP should not be a separatedocument to the one that dictates dailywork practice. The daily work practiceshould be incorporated into the RMP(unless the daily work practice is notcompatible with the production of safedrinking water in which case the RMPneeds to be updated).

S D W A A U D I T S

Figure 1. Results of 2008 audits.

LESSONS FOR OPERATORSVICTORIAN SAFE DRINKING WATER ACT AUDITS

David Sheehan & Leanne Wells

Figure 2. Results of 2009 audits.

Table 1. Summary of major findings from the first round of audits.

• RMPs did not meet the requirements of the Act• Lack of evidence that all the risks that had to be addressed by the RMP had actually been

addressed• Lack of evidence that the RMPs had been implemented in the field• Instruments at water treatment plants (WTPs) not calibrated or maintained, or no records

available to show calibration and maintenance had been undertaken• Current treatment processes not sufficient to manage the identified risks


One of the often-noted criticisms ofRMPs is that they are ultimately all aboutfilling in paperwork and not about gettingthe job done. In the case of poorlyconceived plans, this is likely to be case.Any RMP that is primarily about recordkeeping should be reviewed. Clearly there isa certain amount of record keeping that isnecessary under a risk managementapproach, in order to demonstrate to seniorstaff and auditors that the plan is beingimplemented, but records should serve amore important function than this.Properly used records alert operators toproblems and emerging trends, and alsoprovide valuable information to justifyplant or equipment upgrades.

Ultimately, good RMPs should allow forthe early identification of potential issues

that may affect drinking water quality, andassist, rather than be a hindrance, to theday-to-day activity of operational staff. Thepurpose of the audit process is partly aboutidentifying where plans do not meet therequirements of the SDWA, but it isprimarily about identifying opportunities toimprove practices to ensure that safedrinking water is supplied to the public.

Where to Next

In order to ensure that RMPs continue tocomply with the SDWA, further rounds ofaudits will be held, with the next full roundof audits scheduled for the second half of2011.

With upcoming changes to theAustralian Drinking Water Guidelines andthe ongoing development of a range of

tools to assist water businesses to improve

their risk management practices, the

Department of Health will continue to

work with businesses on improved risk

management.

The Authors

David Sheehan (david.sheehan@

health.vic.gov.au) is Manager, Drinking

Water Regulation, with the Victorian

Department of Health.

Leanne Wells (leanne.wells@health.

vic.gov.au) is a project officer with the

Water Regulation Section of Victorian

Department of Health.

Editor’s Comments

Despite many WTPs passing SDWA or

HACCP or ISO audits we often find the

practices at treatment plants do not match

the plans and often operators really are

unaware of them. In the worst situations,

control point summaries displayed at

treatment plants bear no relationship to

alarm limits in the PLC control system.

Operators have a key role in making the

RMP reflect true practice. If you don’t

know all the details of your RMP, find out.

If what you do doesn’t match the plan, say

where it is different, why it is different and

change it. Alternatively if the RMP is

correct, then you must change what you do.

It is up to management to explain to you

why the changes are necessary and must be

implemented. If when you implement the

changes, it just doesn’t work then make this

clear and again change the plan. The plan is

there to be changed so that it faithfully

represents what is done.

S D W A A U D I T S

Table 2. Summary of opportunities for improvement from second round of audits

• WTP operators should complete visual inspection reports to show they have inspected for anypotential water quality issues e.g. blue green algal blooms, security of storage.

• Records or results not recorded or not recorded at the interval stated in the RMP.• Expired pH buffers and test chemicals still available for use.• Instrument calibration procedures should be reviewed to include tolerance levels• Acceptable differences between online and laboratory instruments need to be developed, and

need to define the action to be taken when instruments are found to be outside limits. (Instrumentswhich are not calibrated are likely to give incorrect readings, and therefore lead to the under orover dosing of treatment chemicals or an incorrect belief that treated water quality is withinspecification.)

• Calibration records could be made available to WTP operators to allow trending andperformance analysis

• Actual values to be recorded rather than a tick a box for pass or fail• Lack of records that deal with drift between calibrations.• Need to ensure chemical deliveries comply with product specifications required by water

business • Water suppliers need to improve communication with water storage managers and to ensure

sufficient monitoring is in place to minimise risks to drinking water supplies.

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