Water Works December 2007 - WIOAwioa.org.au › documents › waterworks ›...

DECEMBER 2007

WATERWORKS DECEMBER 2007 3

Editorial CommitteePeter Mosse, Editor [email protected]

Russell Mack [email protected]

George Wall [email protected]

Direct mail to:

Peter Mosse

WaterWorks Editor

c/-WIOA, 64 Brauman St

Shepparton Vic 3630

Advertising & ProductionHallmark EditionsPO 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 IndustryOperators Association (WIOA). It is published twiceyearly and distributed with Water Journal. Neitherthe WIOA nor the AWA assume responsibility foropinions or statements of facts expressed by contrib-utors or advertisers. All material in WaterWorks iscopyright and should not be reproduced wholly orin part without the written permission of the Editor.

Contributions WantedWaterWorks welcomes the submission of articlesrelating to any operations area associated with thewater industry. Articles can include brief accountsof one-off experiences or longer articles describingdetailed studies or events. These can be emailed toa member of the editorial committee or mailed tothe above address in handwritten, typed or printedform. Longer articles may need to be copied to CDand mailed also.experiences or longer articlesdescribing detailed studies or events. These canbe emailed to a member of the editorial committeeor mailed to the above address in handwritten,typed or printed form. Longer articles may needto be copied to CD and mailed also.

CONTENTSEditorial: The Australian Water Industry -

‘The Other Crisis’ 3

Mittagong Upgrade and Commissioning 6

Fire and Water 9

Water Delivery in Paradise 12

Bundy and Biosolids! 16

In at the Deep End! 19

Coagulant Dosing Control Moves Forward 22

Gold Coast Water Improves 25

E D I T O R I A L

The shortage of water in this country, atthis time, is clearly the major crisis facingthe water industry. There is however asecond crisis. This crisis relates to theability of water supply systems in thiscountry to deliver safe drinking water100% of the time and the ability to ensurethis into the future. The consequences ofthis crisis are worsened by the impendingimplementation of indirect potable reuseschemes.

Operation

Treatment plant operators are often the lastline of defence in the protection of publicfrom waterborne disease. Errors can placethousands of people at risk as has beenamply demonstrated in Walkerton(Canada) and Milwaukee (USA).

In Australia at present:

• There is no minimum standard for theoperation of treatment plants and thereis no minimum educational or trainingstandard required for operators

• There is essentially no minimumstandard for the quality of waterproduced from a water treatment plant.There is certainly no minimum standardfor the production of safe drinking water(The ADWG are guidelines notregulations and do not appear to havebeen widely adopted or used).

• There is no recognition of the need forboth training and experience and theprogressive acquisition of functionalknowledge in the appointment andmatching of operators to treatmentplants. In many cases, water businesseswith a vacancy appoint whomever theythink best for the job regardless of theirlevel of training or competency. Humansociety in many areas recognises theprogression of responsibility andexpectations. A recently qualified pilotwith a qualification to fly a single engineCessna does not fly a jumbo jet – whyshouldn’t this be extended to the waterindustry? There are similar deficienciesin the area of distribution system andwastewater treatment plant managementas well.

• There is no recognition of the need forongoing formal refresher training fortechnical skills. This begs the question ofthe duration of competency. In the faceof changing technology, and changingexpectations, water supply operationsteams must ensure currency ofknowledge and skills. This principal iswell established in our society from firstaid training, life saving and airline pilotsto name just a few professions withresponsibility for some aspect ofconsumer safety.

• Modern businesses including waterutilities are experiencing rapid rates ofstaff turnover. This has been exacerbatedrecently in the technical areas withtechnical staff being tempted by the highsalaries offered by the mining and otherindustries. Finding suitably qualifiedreplacements is often very difficultleading to the tendency to train “on thejob”. This is not compatible with theproduction of safe drinking water 100%of the time. The rate of remuneration forwater industry operators in most cases isnot commensurate with their level ofresponsibility, training, skills or expertisewhich is also adding to the staff turnoverproblem.

Training

Education and training are the cornerstonesof maintaining a modern society. Trainingneeds to be matched to the specificdisciplines and to provide continuity intothe future. The water industry faceslimitations for both current and futureoperations.

THE AUSTRALIAN WATERINDUSTRY - ‘THE OTHER CRISIS’

Peter Mosse and George Wall

Our Cover: A montage of photos fromvarious WIOA events held around thecountry.

WIOA’s 2008 EVENTS

• 2nd Annual WIOA NSW WaterIndustry Engineers & OperatorsConference – 8-10 April 2008 at theNewcastle Jockey Club, Newcastle

• 33rd Qld Water IndustryOperations Workshop – 3-5 June2008 at the Carrara Indoor SportsStadium, Gold Coast

• 71st Annual Victorian WaterIndustry Engineers & OperatorsConference – 2-4 September 2008 atthe Exhibition Centre, Bendigo

4 WATERWORKS DECEMBER 2007

E D I T O R I A L


• The mediocre performance a number of Registered TrainingOrganisations (RTOs) has raised a number of issues:

- RTOs with the Water Industry Training Package are auditedagainst a set of nationally agreed standards the - AustralianQuality Training Framework (AQTF). The role of theseauditors is to confirm that RTO’s are complying with therequirements of the AQTF including Standards 7 and 8covering the competence of RTO staff and RTO assessments.Competency assessment under the AQTF requires assessorswith the necessary knowledge and experience to assess theskills, or assessment to be undertaken in conjunction with anindustry expert.

- Anecdotally it appears that the audit process does noteffectively determine if the RTO employs trainers who havedemonstrable knowledge, skills and expertise in the areas ofthe water industry they train in. There is a need for the auditto be conducted in conjunction with an industry expert,designed to assess individuals who have completed trainingwith the RTO to determine that they have met the assessmentcriteria of the Training Package.

- Accounts abound of staff from RTO’s turning up at waterbusinesses to assess competencies or run courses with limitedknowledge or experience in the subject in question. Oftenthey have to first obtain the necessary knowledge fromoperations staff within the utility.

- Accounts abound of staff from water utilities undertaking aRecognition of Prior Learning or Recognition of CurrentCompetence process with some RTO’s where provided thestaff member can answer some relatively simple questions,they are ticked off as competent for units as high as CertificateIII level. This is often based on time in the job alone.

• Un-nesting of units within the Water Package, particularly atCertificate II and III levels (removal of the need to demonstrateall the knowledge required at lower levels before embarking ona higher level qualification) is also likely to be problematic fortwo reasons.

- Un-nesting should require RTO’s to modify their existingtraining programs to ensure that students have the knowledgeand skills to complete the more specialised training at thehigher levels by building in the lower level competencies intoeach training unit, but there are no guarantees that every RTOwill do this. This is particularly relevant to technicallyoriented training which requires a clear progression of theacquisition of knowledge. These changes at a time when the

complexity of the industry and the expectations of public andregulators require increased operational skills, are a cause formajor concern.

- The number of units required to complete a Certificate II &III has reduced from 22 under NWP 01 to 19 under NWP 07but can be as few as 11 units if direct entry to Certificate III isapproved. Under NWP 07, individual RTO’s can decide atwhat level a trainee can enter, and therefore how many unitsthey must complete to achieve a qualification. There is nodoubt that in efforts to save training dollars, some waterbusinesses will “strongly encourage” RTO’s to do only theminimum amount of training to achieve a Certificate.

• Competency assessment criteria are often generic rather thanspecific and open to a wide range of interpretation according tothe experience and motivation of the assessor.

• Within the training package there is scope for individuals toachieve any Certificate level without necessarily combining anappropriate group of units. For example it is possible for aWater Treatment Plant operator to achieve certificate IIIqualification without having completed any of the key unitssuch as filtration or disinfection or coagulation/flocculation. Tosuccessfully employ or train a person appropriate for a job rolenow requires the Human Resources staff within waterauthorities to have a high level of understanding of the contentof units within the Water Training package and the type ofprocesses the person would be expected to operate. In manyauthorities, HR staff do not have this expertise. The inclusionof tightly controlled “streamed qualifications” which identifyareas of expertise and which specify units to be completed couldhelp eliminate some of this confusion.

• A Level III certification does not necessarily qualify anindividual to operate a treatment plant.

• The completion of Certificate III should be the minimum aimfor all staff who operate a water or wastewater treatment plant.Importantly though, employers need to recognise that thecompletion of the Certificate should not be the trigger that endsall technical training.

• Although it is being addressed by Government Skills Australia(GSA) at present, the Certificate IV units in NWP 07predominately concentrate on front line management. Therange of units does not provide adequate scope for personswishing to complete a technically focussed qualification suitablefor high level plant operation or to provide technical specialistsupport staff to help optimise and trouble shoot plants.

Reporting

The provision of safe drinking water and adequate wastewatertreatment is of such importance to modern society that reportingof performance for external scrutiny is essential. Such expectationsare well established in the financial sector. Pathogens are themajor risk in the provision of safe water to consumers, reportingrequirements need to reflect this knowledge.


• There is no requirement to report meaningful safe drinkingwater measures to regulators on the production of safe drinkingwater. Recording a value of zero (0) E coli is no longer suitableas a stand alone indicator. At a minimum reporting ofindividual filter performance and disinfection performance isrequired.

Plant Registration or Classification

Treatment effort needs to be proportional to the risk and to thesensitivity of a community receiving the water. Systems drawing


water from high risk catchments with a highprobability of pathogen contaminationand/or with a large community with highlysensitive industry, health or touristrequirements require a higher level of plantcapability and higher operational skills. Theplant risk classification therefore needs to bematched with a treatment plant suitable tomitigate the risk. The operator skills setrequired must then meet the complexity andsophistication of the plant itself.


• There is no requirement for classificationor registration of treatment plants.

• There is no formal recognition of theneed for plants capability and operationalskills to match the overall risk profile.

This type of system already exists incountries such as the USA, Canada andNew Zealand. Sadly, Australia is lagging well behind in thisregard.

What We Need!

A national program for the production of safe drinking water isrequired. This program needs to recognise the need for, andintegrate, a classification and registration system for treatmentplants, minimum standards of operation and required levels ofoperation according to the classification level of the plant andformal requirements for appropriate reporting.

More specifically:

• Treatment plant risk and sensitivity profiles need to be assessedand a plant classification established.

• Treatment plant competency requirements need to be assessedand registered. This could be on a rating system similar torestaurants, motels and electrical appliances.

• Minimum levels of operator qualifications and experience needsto be linked to the risk/sensitivity assessment of the plant. Ahigh risk/high sensitivity plant would require a higheroperational skills and experience set than a lower risk/lowersensitivity plant.

• A career path with entry from school, university or TAFE needsto be further developed and promoted in conjunction with GSAand the water industry.

• Training courses need to be expanded and controlled to ensurethat the skills sets identified above can be achieved by entryfrom multiple levels (e.g. school leavers, water industryemployees, university graduates.)

• Specific training course curricula need to be established.

• Competencies need to be specific rather than generic.

• A higher level technical specialist strand (possibly within thedeveloping Certificate IV or Diploma level) needs to bedeveloped to provide the higher level skills sets necessary for theoperation of high risk/high sensitivity plants and the provisionof specialist technical support within the industry. The streamwould also provide a high level technical career path within theoperations sector of the water industry. To achieve this,significant funds need to be injected into resource materialdevelopment.

• Reporting is required against the two key barriers for the controlof pathogens in conventional water treatment, media filtrationand disinfection. Chlorine disinfection (practiced at the vast

majority of Australian plants) is only effectiveagainst bacteria and most viruses. Mediafiltration is the only barrier to protozoanpathogens. Reporting needs to be able todemonstrate that these barriers areconsistently applied.

We realise there are a significant and diverserange of ideas and issues raised within thisarticle. We contend that unless the waterindustry nationally recognises these issues,understands the potential risks of ongoinginaction and works proactively to addressthem, the time bomb that is a major waterquality incident with potentially serioushealth implications and possibly even deathsis imminent. Is it going to be your part ofthe country where an incident occurs? Wehope not.

We welcome any comments, ideas,suggestions or feedback on how we can

further progress our goal to improve the performance of alloperational aspects of the Australian water industry. (You cancontact us on [email protected]).

E D I T O R I A L


Background

Wingecarribee Shire is situated in theSouthern Highlands of NSW,approximately 120km south west ofSydney. The Shire is situated in the middleof the Sydney Catchment Area and wewere under immense pressure to upgradeour systems to ensure the protection ofSydney’s water supply. The Shire has fivesewerage plants located at Bundanoon,Berrima, Moss Vale, Bowral andMittagong and seventy pump stationsdelivering sewage to these plants.

The Mittagong upgrade was long overdueas pollution from aging septic systems inthe northern villages and the inadequaciesof the existing plant were having a negativeeffect on receiving waterways andultimately Warragamba Dam whichprovides drinking water to Sydney. Theupgraded system needed to be capable ofhandling wet weather flows, extendedpower outages and equipment breakdownswith no reduction in effluent quality. Forthis reason all new pump stations weresupplied with 8 hours ADWF storage aswell as dual control systems and dualelectric power supplies. The treatmentplant was supplied with dual powersupplies, a wet weather storage pond andwas hydraulically sized to treat flows thatfar exceeded its design capacity.

It was also a requirement that discharge tothe environment continue to occur in thesame location as previously to prevent anydegradation of previously untouched riversystems closer to the plant. This involved

the construction of a treated effluenttransfer main to pump effluent 6.4kmfrom the new treatment plant site to ourold effluent outfall at Iron Mines Creek. Asthis main passed through the MittagongGolf Course, Council had the option ofreusing the treated effluent. We arecurrently reducing our effluent loadings tothe river by using approximately 20% ofour effluent in plant operations and in anirrigation system at the golf course.

The EPA requirements for the system areshown Table 1.

Lessons and Experiences

As with all large projects thecommissioning of the new schemeprovided the team with a number ofhurdles and many valuable lessons werelearnt which should be considered in futureprojects.

Odour Complaints

Odour complaints are not uncommonduring the commissioning of new seweragesystems. We tried many different ways toaddress these issues with varying results.We lowered pump cut off levels andrebenched the bottom of some wet wells sothey would be kept cleaner. We dosedchemical into some wet wells bothmanually and through permanent dosingsystems and used odour caps on ventstacks. A very regular pump stationcleaning routine was included in ourmaintenance schedule.

Many complaints were received early in themorning from the rising main which wasfed from the main pump station inMittagong. This main went through thecentre of an exclusive residential area so theMember of Parliament for our area wasquickly involved. Insufficient flows in theearly stages were identified as the maincause of the odour problems. The effluentmain from the new plant passed close bythis pump station so we thought if wecould recirculate some of the effluentthrough that pump station as a short termsolution it would solve our immediateproblem. We made changes to the PLCprogram at the plant so the effluent pumpstation started at midnight and installed apipe from the effluent main to the pumpstation recirculating about 10% of oureffluent and making the pump station runmore regularly in the early hours. Thisarrangement solved the problem until thepump station reached its design load.

Delivery System and Inlet Works

All sewage is delivered to the plant throughthe main pump station at 385 kL/hour foroccasional three minute bursts. Thisintermittent flow has a detrimental effecton the treatment process. It results in adrop in the efficiency of the rag removalsystems and the operation of the anoxiczone. It provides the plant with spasmodicflows which make it harder to operate theplant and causes short circuiting. Thismeans operators must be more vigilantwith their monitoring and sampling. It

S T P U P G R A D E

MITTAGONG UPGRADE AND COMMISSIONING

Chris Carlon and Dave CochraneAwarded the Actizyme Prize for the Best Paper by an Operator at the

2007 WIOA NSW Engineers and Operators Conference

Table 1. EPA Licence requirements for the effluent.

Pollutant Units of Measure 50 percentile 90 percentile 100 percentileconcentration concentration concentration

limit limit limit

Ammonia mg/L 1 2 Oil & Grease mg/L - 10pH pH - 6.5-8.5Nitrogen (total) mg/L 7 10Phosphorus (total) mg/L 0.2 0.3Faecal Coliforms mg/L 200Total suspended solids mg/L 10 15 Biochemical oxygen demand mg/L 7 10

Alum & Lime Dosing at the MittagongSTP.


affects plant stability. Short circuiting is amajor problem in our plant consideringthat we have such a stringent licence. It isparticularly bad in the cold HighlandsWinters. Our operators are experienced inanalysing when the plant is short circuitingand quite often ignore high ammoniaresults knowing they are not caused by theneed for more air, but by short circuiting inpeak flow periods. When these results occurthey dilute in our catch pond and haveminimal affect on our effluent. Not beingaware of short circuiting leads to overaeration.

Council is currently investigating theinstallation of VSDs for the pumps at themain pump station, both to save powercosts and to provide a more consistent,controlled delivery of sewage to the plant.Another option is to install a smaller pumpfor normal flows and only use the biggerpumps in periods of wet weather. Basicallyyou are using the main pump station as abalance tank for the plant which wouldhave a positive effect on the process andminimize short circuiting. To eliminateshort circuiting altogether we have askedthat automatic penstocks be installed intothe inlet works at the divider boxes so asthe IDALS can only be fed during aeration.This would eliminate short circuitingcompletely.

Not That Lime System

When the plant was first handed over toCouncil, it was expected that substantialbiological p removal could be achieved. Itwas for this reason that a sophisticated limeplant had been constructed to allow for the

chemical removal of p from the supernatantreturn of the drying beds and sludgelagoons. The designers expected withbiological p removal that levels of p in thesupernatant would have a detrimental effecton the process if delivered back to the headof the works untreated. This would havebeen the case if a good level of biological premoval was achieved.

Unfortunately the method of delivering thesewage to the plant is not conducive tostandard treatment let alone biological premoval. There was no truly anaerobic zoneor temperature control at the inlet works asneeded. Apart from the limited seasonalsuccess which we achieve at all our plants,biological removal of p has essentially notbeen achieved.

After carrying out analysis on thesupernatant we found that p levels wereconsistently low as the alum we were dosingkept it chemically bound. This left us witha complex p removal plant with limited use.It seemed senseless to be using power andhaving to maintain up to 15 machines justto add alkalinity to our IDALS. Not onlythis, but the very material you were tryingto dose to the system would end up settlingout in the clarifier and become just anothersludge you would have to dry and disposeof. An excessive amount of lime was beingused just to maintain alkalinity. The systembecame a constant burden with continualblockages and breakdowns and the use of itcould not be justified.

At present Council operators are manuallyadding lime to the system. We are currentlyinvestigating the installation of a moresimplified lime dosing system or a causticdosing system. We are swinging towardslime as it is a safer chemical, just as effectiveand the cost savings over the plant lifetimewill be significant. In relation to the limedosing system the plant was very wellconstructed but not designed for purpose.

Nutrient Removal Issues

The problems already mentioned combinedwith the fact that we have a very stringentlicence, made achieving licence limitsconsistently very difficult. The shortcircuiting problem, even after allowing foroperator awareness, at times results in over

aeration which results in a drop inalkalinity. We dose alum to ensure we meetour required p limits which once againcompounds our alkalinity problems.Operators must have a properunderstanding of chemical dosing in thissituation. Alum dosing is exponential,meaning it takes significantly more alum todrop p from 0.4 to 0.2 than it does from 1to 0.8mg/L. Also once alkalinity drops, pHproblems occur and the alum become lesseffective resulting in a rise in p. In this casean inexperienced operator will increase thealum dose and compound the problem.Quite often when there is a rise in p wehave to add lime and decrease alum as theproblem is due to low pH, not insufficientalum. At the plant we have pre-dose andpost-dose systems for alum. The postdosing seems to be relatively ineffectiveforcing us to reduce p level down as low as0.3mg/L in our IDALS. I think the post-dose is ineffective due to pH problems andlack of mixing. This makes us dose morealum into the IDALS than we would like.Also because the biomass needs p to workwe have to ensure we don’t strip the p outtotally.

Dosing alum also enhances settling which isnormally helpful. Unfortunately, whensludge starts to settle too quickly it affectsdenitrification which once againcompounds alkalinity problems. Thishappens because a quick settling sludge isnot in contact with the nitrate loadedliquor long enough to achievedenitrification. The alkalinity return whichoccurs during denitrification does nothappen. This can lead an operator to think

S T P U P G R A D E

Wet weather storage at the STP. Looking over the IDAL.


he is over aerating when he actually maynot be. The way we addressed this problemwas to continue returning activated sludgeto the anoxic zone well into the settlingphase to create some mixing so the biomasshas time to denitrify before settling.

As you can see, a lot of the above actions leadto a reduction in alkalinity and if operatorsmake the wrong decisions, serious damage to ahealthy biomass can occur. Remembering thefact that our plant has no proper method ofadding alkalinity apart from manually dosingof lime, you can imagine the problems weface. A proper chemical dosing system whichcould deliver alkalinity consistently during theaeration phase is what is required to achieveplant stability. The line is very thin and veryclose process monitoring is required to achievegood results. All our operators have had extratraining in chemical dosing.

Sumps in Tanks and Ponds

One simple thing which seems to getoverlooked in plant upgrades is theprovision of sumps in tanks and ponds. Wewere supplied with a series of flat bottomtanks and ponds throughout the plantwhich eventually, either for cleaning orrepair purposes will need to be emptied.These include the anoxic zone tanks,average dry weather balance tank, catchpond and sludge lagoons. Totally emptyinga pond or tank becomes difficult whenthere is no sump.

At the commissioning stage of the plant weimmediately saw the importance of acleaning system for the catch pond. Weknew we had no chance of meeting ourlicence unless this pond was kept clean. Weinsisted that a sump and pump includingaccess walkways and associated pipe workto deliver sludge to the head of the plant beinstalled straight away. This included alifting device for retrieving the pump formaintenance and repair. An extension ofthe effluent re-use system to enable us tohose the catch pond out was also necessary.

When we first started using the newcleaning system we would walk down thesides of the pond to gain access for hosing.As the pond was heavily sloped and rubber

lined it was very slippery particularly whenwet. On doing a risk assessment immediaterectification of this hazard was necessary.We investigated the use of differentfootwear, as well as the installation of anon-slip surface. We eventually concludedthat a combination of both was needed. Wepainted the liner with a non-slip surfaceand included in our SWMS that reefwalkers must be worn while doing the task.This method was successful until the non-slip surface started to lift. This againpresented us with a dangerous situation.We investigated the availability of a moreeffective hose nozzle which enabled thehosing to be carried out from the topeliminating the need for entry. Hind-sightis a wonderful thing but this is still ourwork practice today. This task is carried outonce a fortnight.

We also found that we needed to removegrit from the anoxic zones every two years.If that wasn’t done we would havecontinuous problems with the mixers inthis area. Once again there are no sumps inthese tanks. This causes us to have to hiresuper suckers and enter a confined space tocarry out the task. If sumps were providedwe would definitely be able to save the costof hiring a super sucker and possibly evenentry.

Only this year we installed a sump andpump into the average dry weather balancetank for cleaning purposes. This makescleaning this area of the plant a lot easier.The sludge lagoons will be our nextchallenge. They are rubber lined lagoonswhich one day will require maintenance. Itwill be a problem to empty them out tocarry out this maintenance as they don’thave sumps.

Training and Upskilling Operators

If staff have been operating trickling filterplants and are now being asked to run thenew plant they will need considerabletraining, particularly in chemical dosing.Staff should be well trained in theoperations of the new system so they canlook forward to system commissioningrather than approaching it with fear anduncertainty which creates negativity at thebeginning. They should be involved in thepre-commissioning testing to gainexperience in operating the plant beforesewerage is introduced. Experiencedoperators should have a chance to discussdesign issues before construction starts andhave input into areas of concern.

Design Issues

When a project includes reticulation workand plant construction, both sectionsshould be preferably designed by the same

company to ensure compatibility in design.This prevents the situation of having theintended design of the plant as biological premoval yet having the reticulation systemdeliver sewerage to the plant in a mode thatmakes this impossible. Plant shortcircuiting should be expected and rectifiedat the design stage. Asset managers shouldallocate sufficient funds during the first fewyears of operation to resolve issues whichmay have been overlooked.

Conclusion

After six years since commissioning, wenow have a plant which treats all theeffluent from Mittagong and the NorthernVillages and consistently achieves licenceconditions. We are very fortunate to havededicated and experienced operators andengineers who often work beyond theirrequired duties to ensure high standards aremaintained at all times. Incidentally, theMittagong plant is nearing its designcapacity and we are preparing for the nextupgrade.

Acknowledgements

Thanks to Council for allowing me theopportunity to present this paper, the teamfrom the Department of Commerce whoworked closely with us during thecommissioning stage to achieve the desiredresults and to Mark Williams who managedthe project for Council.

Thanks also to Council operators includingIan Freere and the late Phil Ohearn whoworked for many hours unpaid during thecommissioning and initial operations of theplant.

Special thanks go to Mark Bruzzone fromMWH whose expertise during the initialoperations of the plant proved invaluable.

The Authors

Chris Carlon ([email protected].

gov.au) is Supervisor of Sewerage Plants &

Pump Stations, and Dave Cochrane is the

Head Operator of Mittagong STP & Pump

Stations, both for WSC.

S T P U P G R A D E

UV Filters. Drying Beds.

B U S H F I R E R I S K M A N A G E M E N T

As storage operators we often viewfloods as the predominant risk toour structures, but climate changemay result in bushfires becomingincreasingly prevalent in EasternAustralia. This change in climatemay result in more intense andvariable rainfall followed by longperiods of hot dry weather such ashas been experienced over the lastdecade. Potentially this will leadto periods of rapid growthfollowed by long dry spells thatdry vegetable matter quickly andcreate increased natural dry fuelloads and risk of wildfire.Consequently it is imperative that ruralutilities implement sound bushfire riskmanagement protocols across all aspects oftheir business operations. Similarly recovery

from bush fires needs to be optimisedthrough advanced planning.

Southern Rural Water (SRW) operatesseveral large dams and smaller diversion

weirs in southern Victoria.Amongst these are two highhazard dams (LakeGlenmaggie and Blue RockLake), and a major diversionweir (Cowwarr Weir) locatedin Gippsland. These sites arecritical to water harvestingand delivery for a variety ofstakeholders. They provideraw water to Victoria’s majorpower generators, industrialand urban consumers withinthe Latrobe Valley, MacalisterIrrigation District customersand environmental flows tothe rivers of the GippslandLakes system.

Lake Glenmaggie spans the MacalisterRiver; Blue Rock Dam the Tanjil River and

FIRE AND WATERJohn Cameron

Judged Best Operator Paper at the Annual WIOA Victorian Water Industry Engineers and Operators Conference 2007


B U S H F I R E R I S K M A N A G E M E N T

Cowwarr Weir diverts water from theThomson River.

In December of 2006 these sites were allthreatened by fire designated as the GreatDivide South Bushfire. At the same timestaff and the assets at Cowwarr Weir werethreatened by a deliberately lit wildfire.

The lessons learned by SRW from thesefires can be used by water authorities tobetter prepare for future fire events. Theseinclude improved risk management of firethreat to capital infrastructure, physical andnatural environments and trauma toindividuals and the broader community.

Case Study: Wildfire at CowwarrWeir

In December 2006 SRW recognised thatthe Great Divide South fire had thepotential to place several of its sites at riskand consequently rapid action was taken toprepare them for potential onslaught of thatfire. All sites were assessed for risk andpriorities set for protection.

Lake Glenmaggie was assigned a highpriority as the infrastructure for that sitewas located in natural bush. Availableresources were concentrated on protectingthat asset against threat from fire or ember

attack. All overground plastic water pipeswere buried or replaced with steel, allbuilding apertures were screened to protectagainst ember intrusion, fire protectionequipment was tested, sprinkler systemswere installed on critical buildings andresidences, excess dry fuels were clearedfrom critical infrastructure, spouting wasfilled with water, personnel fire protectionkits were prepared (torches, woollenblankets, fire beaters), fire reports weremonitored continually and personal andcorporate fire plans reviewed andcommunicated.

Cowwarr Weir and Blue Rock Dam, on theother hand, were classified as low risk asthey were located in large clear areassurrounded by pasturelands. Minimalresources were assigned to fire protection atthose sites. This proved to be a mistake thatwould later place two staff and a familymember at extreme risk and expose thebroader organisational community tounnecessary trauma.

On December 19th a deliberately litwildfire broke from nearby bushland andraced at an alarming and unchecked rateacross dry farmland towards Cowwarr Weir.Staff preparing the site against potential fire

threat were suddenly forced to flee to theprotection of the nearby weather boardresidence. The fire then spread rapidly tothe adjoining garage and immediatelyplaced the residence under dire threat.(Fortunately staff had all completed theDSE Basic Wildfire Awareness accreditationand were well skilled to manage the firethreat.)

Stored mulch heaps and exposed fodderignited, stored tyres smouldered, andfencing commenced to burn and the fireentered the office and workshop. At theheight of the firestorm power, phone andwater supply failed, daylight was obliteratedand windstorms created by the fire batteredthe area. Those in the house becameconcerned about the ability of the woodenresidence to withstand the onslaught of thefire and made plans to evacuate to a saferlocation. They were able to communicatewith their supervisor and emergencyservices but no direct support was availableand, at that time, they believed they were atextreme risk of being engulfed by fire.During lulls in the wind they were able toleave the building and extinguish spot firesthreatening it.

At the same time reports were beingreceived at ABC radio that the CowwarrWeir residence was on fire and two womenresidents were missing. Colleagues andfamily were distressed as they were unableto gain accurate information about thepeople. Unfortunately the report continuedto receive national airplay for a further 12hours despite the fact that the ABC wascontacted and informed about the truesituation. After the fire front had passedseveral people placed themselves at extreme(and unnecessary) risk by returning to thesite to provide immediate assistance to thesupposedly trapped people.

During the event the supervisor wasprovided with constant updates via mobilephone conversations with the affected staff,however logistical problems arose as theresult of the unprecedented number of callsbeing made to the affected staff byconcerned third parties. Consequently therewas concern that mobile phone batterieswould fail.

After several hours, the fire front had passedand the affected people emerged to surveythe damage and advise emergency servicesthat they were no longer at risk.

Rehabilitation of the physical assetscommenced immediately and was still inprogress several months later. Throughoutthe recovery period SRW relied heavily onsupport and assistance from externalutilities.


SRW also elected to invest heavily in ensuring that risks fromfire would be reduced should bushfire threaten any site in thefuture.

Lessons Learned

The knowledge gained from the fire at Cowwarr Weir can besummarised as follows:

• The best defence against the mental traumas and physicalimpact of bushfire is to develop, review and rehearsebushfire action plans on a regular basis.

• There is a potential risk to staff, contractors and physicalassets.

• Fire activity cannot be predicted accurately.

• Similar standards of protection must be applied to all sites

• Water authorities with assets in rural locations must ensurethere is a clearly communicated fire action plan in place at alltimes.

• Resources must be invested in preparing rural water locationsfor the eventuality of fire

• Water authorities must undertake regular fire audits at all sitesat risk of bushfire.

• Fire plans must be tested and rehearsed regularly.

• All staff that may be exposed to fire should undertake BasicBushfire Awareness training (course available atwww.dsetraining.org.au)

• Sensible actions will ensure that firestorms can be confrontedand managed if required.

• Personnel external to the fire can be traumatised by theuncertainty surrounding a fire event (The SRW CEO statedafter the fire “I never want to have staff placed at such a riskagain”)

• It is essential to establish a working relationship with localmedia to ensure released information is accurate and does notplace others at risk.

• Reliable communication with staff is essential. (SRWHeadworks staff have been issued with trunk radios, theirvehicles fitted with tracking devices and a proceduredeveloped requiring them to divert their mobiles to a centrallocation during emergency incidents in order to minimise thedrain on their mobile phones and allow them to concentratetheir energies on the incident.)

Conclusions

Bushfires threaten infrastructure, water quality andorganisational capacity to cope. They have long-termconsequences that impact on organizations, individuals andnatural environments.

Recovery from any incident requires co-operation betweenorganizations. Bushfire is no exception to this. Consequently itis essential that partnership arrangements be established andmaintained, in advance, with external support organisations andutilities.

The media plays a vital role in natural disasters andorganisations need to develop strategies for managingcommunication with media in advance of any event.Communication needs to be succinct, accurate and timely.

The Author

John Cameron ([email protected]) is Headworks Supervisorfor Southern Rural Water in Gippsland Victoria.


W A T E R S U P P L Y

WATER DELIVERY IN PARADISEDavid Dickson

Like many Queensland tourist areas,Hamilton Island must cater for a variablepopulation of between 1,500 and 4,000people. Being privately owned andoperated, there is a need to produce andcontinually supply high standard potablewater whilst minimising operational costs.Daily water consumption ranges from1.2ML up to 2.4ML during peak times.

The island has four freshwater collectionand storage dams (Table 1) but theircapacity is not sufficient to supply water allyear round. As the names suggest, three ofthe dams are situated within the airportarea.

Hamilton Island resort operates a DAFFwater treatment plant, and a ReverseOsmosis (RO) plant to treat sea water as aback up during times of limited fresh wateravailability or when water quality issuesrequire an alternative supply.Unfortunately, the RO plant is expensive tooperate and its use must be minimised.Disinfection in the form of chlorine gas andozone is employed.

There are a number of challenges which theoperators must meet in order to maximisethe production of high quality water at aminimal cost. This paper describes some ofthese challenges and how we are able toachieve a satisfactory outcome. Goodrainfalls were recorded early in 2006 and in2007, which filled all four dams to

capacity. South Runway and NorthRunway dams are relatively shallow withdepths between 2-3 metres. Their shallownature combined with the lack ofvegetation due to their close proximity tothe airport make them susceptible to algalblooms in the warmer months. Water inthe storage also has a relatively highelectrical conductivity (EC) due toevaporation and sea water ingress

The Treatment System

DAFF Plant

The DAFF plant produces around 2.0 MLper day.

The DAFF plant consists of 2 DAFF tanks,fed from a single flocculation tank. Theflocculation tank provides 15-20 minutesdetention time depending on flow rate. TheDAFF system is very robust and can handle

variations in raw water quality reasonablywell. As evidence of this Table 2 outlinesthe DAFF plant performance during recentrain events where 220 mm fell in 24 hrsand the raw water turbidity went from theusual 15 NTU up to 180 NTU.

Ozone Disinfection

The ozone generator can produce 400 g/hrof ozone gas. The target residual is between0.30mg/L to 0.50mg/L depending on thequality of the raw water and algal counts.

Once the treated water has left the DAFF itis injected with ozone saturated filteredwater. Any organic material that has notbeen taken out by the DAFF process isoxidised by the ozone gas during a fiveminute contact period.

This process is especially important in thetreatment of blue green algae as the ozoneattacks the cell walls and destroys the algaltoxins that are released by the algae.Ozonation also oxidizes iron andmanganese compounds that may be presentin the filtered water and this helps improvethe taste of the treated water.

BAC (Biologically Activated Carbon)

Once the treated water has been throughthe ozone disinfection process it passesthrough a BAC filter where any toxins ororganic compounds are removed by thebacteria.

Care must be taken with the ozonedisinfection as a residual that is too highcan sterilise the BAC bed and turn it intoan activated carbon filter. Backwashing ofthe filter must also be monitored to ensureover washing does not reduce the bacteriato an extent where it is not effective atremoving organic compounds produced bythe ozonation process. A monthlymonitoring regime provides cell counts forboth pre and post BAC ozone treatment toensure the process is operating correctly.

Reverse Osmosis Plant

Reverse Osmosis (RO) is used to convertseawater into safe drinking water. The RO

Table1. Island Storages and Capacity.

Storage Capacity (ML) Surface Area (m2) Usable Capacity (ML)

Terminal Dam 157 17000 149South Runway Dam 166 88000 117North Runway Dam 205 109000 184Palm Valley Dam 74 12500 69

Table 2. DAFF Plant Performance.

Date 1-2-2007 2-2-2007 3-2-2007 4-2-2007 5-2-2007 6-2-2007

Conductivity (μS/cm) 1,236 1,203 970 930 890 860Final water pH 6.9 6.8 6.6 6.9 6.9 6.9Final water turbidity (NTU) 0.25 0.2 0.8 0.24 0.51 0.27Filtered water turbidity (NTU) 0.33 0.53 1.8 6.35 1.14 2.3Chlorine residual (mg/L) 1.71 1.88 2.13 1.63 1.57 2.46Flow rate (L/sec) 24 18 20 20 26 20Alum residual (mg/L) .15 .15Alum dose (mg/L) 70 70 70 65 75 75


plant at Hamilton Island is capable ofproducing 1.4ML per day but it iscurrently operated at around 50% to 75%of its capacity to compliment the DAFFprocess

Raw water pumps deliver seawater with anEC of around 54,000 μs/cm to the ROplant where the raw water passes through aseries of filters. The first are the Spinklinfilters which remove larger inorganiccompounds such as shell, sand and grit.Water is then split into two banks, eachbank consisting of four sand and fourcarbon filters. One micron filters furtherfilter the water which is then stored in two20,000 L tanks. These tanks supply thehigh-pressure pumps that feed the four ROBanks. Each RO bank consists of fivepressure vessels each containing sixmembranes. One bank is capable ofproducing 4.2 L/sec of permeate flow froma feed rate of 12 L/sec with a final averageEC reading of 500μs/cm. The water leftover by the process, which has an EC ofaround 72,000 μs/cm, is returned to theocean via an outfall pipeline.

Chlorine Dosing

The final step in the treatment process isthe addition of chlorine. The final water isdirected to a 1.5ML treated water storagewhich is chlorinated to around 1.2 to 2mg/L to ensure a residual in thereticulation network of 0.5 to 0.7mg/L inthe dead ends.

Operational Challenges

There are three main operationalchallenges:

• Ensuring all barriers are in place whentreating algal blooms

• Reducing the EC of the potable water

• Minimising maintenance andoperational costs of RO treatment.

Managing and Treating Algal Blooms

Algal blooms are an inevitable part of theannual weather cycle. The algal countsfrom the Hamilton Island storages for theperiod August 2006 through to December2006 are shown in Table 3.

North Runway dam is the primary rawwater source for supply to the DAFF plant.Algal counts increase as temperatures rise.High numbers of algae are transported tothe Terminal dam from North Runway

dam. It is at this point increasedmonitoring checks are made at the plant toensure all barriers in place to remove anyalgal toxins are functioning correctly.

Palm Valley dam is used to blend with theother two storages when algal countsbecome too high. It is also used as a stand-alone water supply when North and Southrunway dams become unusable. Table 3shows algal counts in Palm Valley aresignificantly lower than the other threestorages.

An interesting point is that of the fourstorages, Palm Valley is the most protectedfrom human impact and has a relativelyuntouched catchment area. The algalcounts show how important it is to protectcatchments and the benefits this can haveon water quality.

A program of bank restorationincorporating fencing and re-vegetation tohelp reduce nutrients in sediment runoff iscurrently under way.

When algal blooms do occur, there areseveral barriers in place to ensureproduction of safe drinking water. Theseinclude:

• The DAFF plant where the bulk of thealgae is removed,

• Ozonation to destroy any cells that havemade it through the DAFF process.


Table 3. Storage algal counts (cells/mL) from August 2006 to December 2006.

Storage Aug-06 Sep-06 Oct-06 Nov-06 Dec-06

Palm Valley Blue Green Algae 0 0 0 68,833 30,400Palm Valley Total Algae 43,000 45,000 250,000 150,000 170,000Terminal Dam Blue Green Algae 8,185 54,899 126,000 42,000 135,000Terminal Dam Total Algae 290,000 4,800,000 3,700,000 330,000 780,000Nth Runway Blue Green Algae 910 12,343 10,467 530 70,143Nth Runway Total Algae 3,400,000 7,100,000 2,100,000 1,500,000 4,700,000Sth Runway Blue Green Algae 13,725 50,000 99,800 216,667 17,767Sth Runway Total Algae 740,000 2,800,000 4,100,000 2,200,000 1,500,000

Table 4. EC of water in Hamilton Island storages (μs/cm).

Date Palm Valley Nth Runway Sth Runway Terminal Dam DAF Final Water

01-Nov-06 260 2110 2420 1430 128416-Nov-06 270 2250 2470 1640 125408-Dec-06 280 2520 2670 1820 112020-Dec-06 300 2640 2800 2020 134227-Dec-06 310 2850 2900 2070 174003-Jan-07 280 2680 2890 1760 144118-Jan-07 310 2960 3030 1390 113824-Jan-07 240 1670 2630 1320 122502-Feb-07 190 360 1900 930 970

Schematic of the Hamilton Island treatment system.

• Biologically activated carbon removes anycompounds created by the ozone process

• Monthly sampling of pre and post ozonetreatment.

Reducing EC

Water in all the storages has a high EC(Table 4). This is largely due to thegeographical nature of the island and thefact that the storages are occasionallyinfiltrated by king tides. Both North andSouth Runway dams were formed fromwhat was formerly a natural bay before thepresent day airport was constructed.

Readings of above 3,000μs/cm for SouthRunway dam are not uncommon, whichmakes reducing the EC level difficult. Toutilise water from South Runway dam itfirst needs to be pumped into NorthRunway dam, thereby increasing the EC inNorth Runway dam. For these reasonsSouth Runway dam is presently used as aback up water supply.

Terminal dam which feeds the DAF andRO plants, has its own catchment area andis topped up by annual rainfall. Both PalmValley dam and North Runway dam arepumped to the Terminal dam before

treatment at the DAF plant. The EC levelin North Runway dam can reach 2,900μs/cm, generally in the warmer months andas the storage levels decrease.

Palm Valley dam has the lowest of all thestorage EC’s with readings of around250μs/cm, however it has a very limitedcapacity of 74ML.

Reducing the EC of the final water to lessthan 1,000μs/cm is crucial to reducecorrosion damage to pumps, impellors,treatment plant assets and the metalcomponents of the reticulation network.

However in practice this is not alwayspossible.

Water from Palm Valley dam is blendedwith water in North Runway and Terminaldams to help reduce the EC. This generallyreduces the EC to between 1100μs/cm and1350μs/cm with a practical target< 1200μs/cm achieved.

Early rainfall in the past 2 years has reducedthe overall EC readings of all the islandstorages. As the storage levels fall, generallythe EC readings increase and twomanagement options are available.


Table 5. Comparison of RO and DAFF Power Usage at different flow rates.

Date Number RO Power RO Flow rate DAFF Flow Rate Power Banks running Kilowatt Hrs (L/sec) (L/sec) Kilowatt Hrs

12/12/2006 3 39 12 20 813/12/2006 3 40 12 20 714/12/2006 3 37 12 20 715/12/2006 3 41 12 20 916/12/2006 2 29 8 25 517/12/2006 2 27 8 25 918/12/2006 2 28 8 18 819/12/2006 3 35 12 25 720/12/2006 2 31 8 25 8


Option 1 - Pump from Palm Valley dam to the Terminal dam. Byblending water from Palm Valley, which has a generally low EC, theEC readings in Terminal dam can be reduced.

Option 2 - Reduce the flow rate from the DAF and increase the flowrate from the RO. This is very effective at lowering the EC.

RO Maintenance and Operational Costs

Power requirements for the DAFF and RO plants are shown in Table5. The RO process requires large amounts of power and is veryexpensive to run. The RO plant uses nearly five times as much powerto produce generally less than half the water of the DAF plant.

Due to the corrosive nature of seawater, the RO is also costly from amaintenance and an operating perspective. Seawater corrodeseverything in the RO plant, even the shed that houses the plant.There is a constant program of painting and replacement of non-stainless parts. A full time fitter and turner is employed to run andmaintain the RO plant because of the constant repairs andmaintenance required.

The membranes used in the RO plant have a life span of 4-5 yearsprovided they remain free from mechanical failure. The cost ofreplacing membranes is somewhere in the range of $1,600 each andthere are 4 banks each with 30 membranes. The total cost of themembranes is around $190,000. There are 2 banks of 1-micronfilters, each bank houses 32-filter cartridges at a replacement cost of$21.00 each. One micron filters need to be replaced about every 3-4weeks depending on the quality of the carbon in the filter banks. Theactivated carbon in the filters has deteriorated and is due to bereplaced; hopefully this will increase the life of the 1-micron filters.

The Future

Hamilton Island is experiencing a development boom at present witha new resort, staff accommodation, yacht club and many privateresidences presently being constructed.

The current challenges are being met by:

• Constant testing and calibration of all our monitoring equipment

• Construction of silt traps to protecting our storages and catchmentsfrom the effects of all the new developments

• Revegetating areas susceptible to erosion

• Rationalising the use of the RO plant.

The new challenge will be to ensure current infrastructure is sufficientto meet the demands of these future developments and implementingnew technology to minimise impacts on the very special environmentin which we live, work and play.

Acknowledgements

Thanks to Jock Edgar, Andy Trigg, Harry Hornstra, StevenShortland, Shane Burt from Hamilton Island Enterprises for theirsupport and assistance in developing this paper.

The Author

David Dickson ([email protected]) is SupervisorWater Treatment, for Hamilton Island Engineering & Services.


Background

Changes to environmental legislation haveled to more rigorous conditions beingplaced on the management of WastewaterTreatment Plants (WWTP). As aconsequence, the latest EPA licence forBundaberg City Council (BuCC) has aspecific requirement that biosolids shouldnot be disposed of or stored onsite; and thata waste management program be developedidentifying waste management strategieswith a focus on more efficient andbeneficial use of biosolids.

A tender for “Beneficial use of Biosolids”was advertised and BuCC entered into acontract with Camreay Holdings to removeall of the biosolids from Council’sWWTPs. The program has commencedwith the removal of biosolids from our twolargest Wastewater Treatment Plants at Eastand Millbank.

Millbank External Aeration WWTP.

Biosolids Production

Treatment of wastewater at the EastWWTP is achieved by way of twobiological trickling filter (TF) processstreams and an extended aeration (EA)stream. The plant treats an Average Dry

Weather Flow (ADWF) of approximately6.0 ML/D from the East Bundabergcatchment. The influent flow is splitapproximately 1 ML/D to A plant (TF), 2ML/D to B Plant (TF) with the remaining3 ML/D going to C Plant (EA).

Solids from the primary sedimentationtanks of A & B plant are transferred to theprimary digesters for stabilisation. WasteActivated Sludge (WAS) from C Plant ispumped from the aeration ditch to thesludge thickener. The thickened sludge isthen transferred to either of the A, B or CPlant digesters for stabilization, prior todewatering on the sludge drying beds.

The dewatered biosolids from the dryingbeds is stockpiled in a clay lined, bunded,hard stand area. Camreay Holdings thencollects the stockpiled biosolids andtransports it to the farm for processing.

Millbank WWTP is an extended aerationplant with an ADWF of 4 ML per/day.Raw sewage arrives at the plant from the

Avoca/Branyan and Millbank catchments.Millbank WWTP also receives all septicdischarges. WAS is pumped from theaeration ditch to the belt press fordewatering. The cake from the belt press istransferred directly onto an EPA licencedwaste transport vehicle for transport to theCamreay Holdings farm. Approximately50m3 per week is delivered in two 5m3

loads each day. Delivery of biosolids iscarried out from Monday to Friday. Thisfrequency has enabled the operators toreduce odours associated with the biosolidsremaining in the truck for long periods oftime.

Delivery of the sludge.

The primary differences in biosolidsproduction between the two WastewaterTreatment Plants are listed in Table 1.

Figure 1 demonstrates the quantity ofbiosolids transported this financial year.

Biosolids Quality

The type of industry contributing to acatchment can have a significant impact onthe final end use for a biosolids product.Typical industries discharging into theBundaberg system include:

B I O S O L I D S M A N A G E M E N T

BUNDY AND BIOSOLIDS!Keith Nicholle, Graham Campbell and Kerry Dalton

Awarded the Actizyme Prize for the Best Paper by an Operator at the 2007 Queensland Water Industry Operations Workshop

Table 1. Summary of biosolids production characteristics at the two plants.

Millbank WWTP East WWTP

% Solids = 14 to 16% % Solids = 25% Belt Press Drying BedsAerobic process Anaerobic processLess stable on application Digested biosolids more stable on applicationAbility to waste in any weather Dependant on weather conditionsMore prone to odour problems on application Less problem with odour on applicationWaste and dispose same day. More time consuming waste processBiosolids removed per week = 50m3 Biosolids removed per week = 28m3 (average)Final use-ground application Final use-composting

Total capacity of drying beds - 66Kl

Figure 1. Biosolids removal for the year to date.

• Food processing plants

• Light industry

• Sugar refinery mill

• Rum distillery

• Soft drink brewery

The lack of heavy industry, ultimately

results in a high quality biosolids product,

which is very low in heavy metals and other

contaminants. High grade biosolids allows

the end user a wider scope for land

application.

Analysis of the biosolids product is carried

out to determine the contaminant levels.

The concentrations are then compared

against the acceptance limits as prescribed

in the NSW EPA Guidelines (2000) to

establish the grade of biosolids. Table 2

indicates the quality of the biosolids from

both the Millbank and East WWTP’s with

comparisons to the New South Wales

Environmental Protection Agency

(NSWEPA) guidelines (2000).

Transport

The transportation of the biosolids from

the treatment plants to Camreay Holdings

farm required a separate licence under EPA

legislation. Applications were made to the

EPA and as part of their licencing

conditions for waste transportation BuCC

had to implement the following:

• Procedures for the management of spills

• A waste docket system for capturing

quantity and frequency of waste removed

from site

• Sealing and covering of trucks for the

transport of biosolids



Table 2. Quality of biosolids.

Parameters NSW Guidelines Gradings1

Grade A Grade B Grade C Grade D East Top East Bottom Millbank (mg/kg)3 (mg/kg)3 (mg/kg)3 (mg/kg)3 Beds Beds

Arsenic mg/kg 20 20 20 20 <5 <5 5.0Cadmium mg/kg 3 5 20 32 <1 2.0 1.0Chromium mg/kg 100 250 500 600 10.0 25.0 19.0Copper mg/kg 100 375 2000 2000 34 310 481Nickel mg/kg 60 125 270 300 6.0 24.0 21.0Lead mg/kg 150 150 420 500 20.0 101.0 44.0Zinc mg/kg 200 700 2500 3500 75 424 582Selenium mg/kg 5 8 50 90 <5 <5 <5Mercury mg/kg 1 4 15 19 0.7 2.3 2.1

DDT ug/kg 0.5 0.5 1.0 1.0 <50.0 <50.0 <50.0DDD ug/kg 0.5 0.5 1.0 1.0 <0.50 <0.50 <0.50DDE ug/kg 0.5 0.5 1.0 1.0 <0.50 <0.50 <0.50Aldrin ug/kg 0.02 0.2 0.5 1.00 <0.50 <0.50 <0.50Chlordane ug/kg 0.02 0.2 0.5 1.00 <0.50 <0.50 <0.50Heptachlor ug/kg 0.02 0.2 0.5 1.00 <0.50 <0.50 <0.50HCB ug/kg 0.02 0.2 0.5 1.00 <0.50 <0.50 <0.50Lindane (BHC gamma) ug/kg 0.02 0.2 0.5 1.00 <0.50 <0.50 <0.50BHC ug/kg 0.02 0.2 0.5 1.00 <0.50 <0.50 <0.50PCB’s ug/kg 0.02 0.2 0.5 1.00 <10 <10 <10

1. In the absence of guideline for the reuse/disposal of biosolids in Queensland, the guidelines published by the NSWEPA are used.

Tota

lPe

stic

ides

Figure 2. Compost Temperatures.



In this case, EPA Waste Trackingexemptions apply as the biosolids are beingtransported to a farm for use as a soilconditioner or fertiliser. Camreay Holdingswas also required to comply with EPALicencing requirements for transportingand re-processing biosolids waste.

Reuse

The NSWEPA Guideline for Use andDisposal of Biosolids Products (2000) wasalso used as a guideline for end useapplication.

Spreading the sludge.

Prior to commencing biosolids removal andreuse, Camreay Holdings had to prepare anEnvironmental Management Plan (EMP)for submission to EPA. The EMP includedaspects such as:

• Soil condition

• Biosolids quality for application

• Potential for groundwater, surface waterand soil contamination

• Geographical aspects including contoursand natural waterways

• Biosolids receival and compostingprocesses

• Reporting requirements (data capture)

The biosolids cake from Millbank is landapplied using a muck spreader at a ratepredetermined by calculating theContaminant Limited Biosolids ApplicationRate (CLBAR) and the Nitrogen LimitedBiosolids Application Rate (NLBAR) asdescribed by the NSWEPA Guidelines(2000).

Initial odour problems were overcomethrough a consultative process between theoperators and Camreay Holdings. It was

found that odour was significantly reduced

by applying and incorporating the biosolids

into the soil immediately after delivery to

the farm. In the case of wet weather there is

a bunded ramp at the end of a private all

weather road where the biosolids can be

deposited until they can be applied in more

suitable weather conditions.

Composting

Biosolids from the East WWTP are

composted by Camreay Holdings. The

biosolids are combined with a prepared bed

of ground up sugar cane at a predetermined

Carbon/Nitrogen ratio. Once there is

sufficient biosolids, the biosolids and sugar

cane are mixed using a front end loader and

windrows are formed. The windrows are

irrigated or turned as required depending

on the temperature. Temperatures between

55°C and 70°C are maintained for a period

of at least five weeks. These temperatures

are optimal for the production of high

quality compost. The whole windrow must

be turned and temperatures must be

maintained to avoid pathogen and weed

contamination of the compost. This also

meets the requirements for Australian

Standards AS 4454-2003, Compost, Soil

Conditioners and Mulches. Figure 2 shows

typical temperatures achieved through-out

the composting process.

When the temperature drops significantly

and the composting process is nearing

completion, the compost is stockpiled and

left to mature. This process can take up to

12 weeks. After maturation, a sample is sent

to the Soil Foodweb Institute for analysis

and grading.

An example of an analysis is shown in

Table 3. This compost is suitable for

application as a soil conditioner. Compost

of this quality would increase the carbon

content as well as improving soil, which has

been damaged and/or nutrient depleted

from over-use. High quality compost can

also assist with water retention.

Sludge from the belt press.

Camreay Holdings intends to package the

compost in 20 kg bags for the domestic

market, as well as selling the compost in

bulk to farmers. Compost of this quality

can be used to produce compost tea. Other

than sugar cane, which has been grown on

the blocks with applied biosolids, Camreay

Holdings have recently harvested a crop of

sunflowers and plan to follow this with a

crop of maize. This crop has been grown

without the use of additional fertilizers.

Camreay Holdings believe that the future

lies in liquid biosolids and as a recycler and

end user, this is an option that is being

explored with interest.

BuCC and Camreay Holdings are excited

about being involved in a project that

presents a long term, environmentally

sustainable solution to waste disposal. The

perception of biosolids is no longer that of

a waste product; instead it has become a

resource with a growing number of

applications. BuCC Treatment Plant

Operators have enthusiastically contributed

to this process working with Camreay

Holdings to overcome any problems and

issues which may have arisen during the

initial inception.

The Authors

Keith Nicholle ([email protected].

gov.au) is a Treatment Plant Operator, and

Kerry Dalton an Environmental Officer

(Water and Wastewater) both with,

Bundaberg City Council. GrahamCampbell is the proprietor, Camreay

Holdings.

Table 3. Compost Analysis Results for November 2006.

Active Bacterial Total Bacterial Active Fungal Total Fungal Hyphal Flagellate Protozoa Ciliate Total Plant Biomass Biomass Biomass Biomass Diameter Numbers/g Nematode Available(μg/g) (μg/g) (μg/g) (μg/g) (μm) Amoebae Numbers Nitrogen

#/g (from predators)

Desired Ranges 15-25 100-3000 15-25 100-300 (um) 10000+ 10000+ 50-100 20-30 kg/haResults 80.9 917 1.87 460 3.0 10026 3730 801 0.87 75-100Suitability Excellent Good Low Excellent Disease suppressive Good Low OK Low

fungi presentExtracted from Soil Food Web website (2007)


Fire and Rain!

I was excited! After three years in businessdevelopment and the commercial side ofwater treatment, I was about to return tothe front lines of water treatment. I hadbeen watching the news reports coveringthe bushfires which burnt so wildly overthe Christmas-New Year period of 2006,predicting the impact it would later haveon water supplies. Having been heavilyinvolved in post bushfire water treatmentduring my time spent with North EastWater in Victoria, I was looking forward tothe challenges that awaited me, when Ireturned to the battlefield that is potablewater treatment.

On the 8th of January 2007, I started workas Water Treatment Technologist withGippsland Water. Without having had achance to settle in, on my second day ofemployment, Gippsland Water wasapproached by the Lions Club of Victoriafor advice and assistance on treating dirtywater from the Macalister River which haddegraded significantly after the fires.Having the luxury of being new toGippsland Water, I was not yet overloadedwith other projects and was delegated thetask of working out a suitable means oftreating what was once pristine mountainwater.

Water samples were delivered for testing,and a site visit was undertaken to assessoptions and available infrastructure, thatcould some how, be utilised as anemergency water treatment system. Onarrival on site, the situation became clear;

280 children staying in the village wereallocated water for only 4 hours per day,such was the shortage of supply and thecost of trucking water to the remote town.No hot water was offered for bathing tofurther minimise use. Exhausted volunteerswho had just fought off the fires, were nowrebuilding the water distribution system,and awaiting a means of treatment.

After assessing what was available, thedecision was made to utilise the townswimming pool as an emergency clarifier,and work began on determiningappropriate chemicals for flocculation anddesigning dosing systems. Several waterindustry suppliers provided assistance anddonated their time, equipment andchemicals to help the struggling charity,and the communities they serve. Within aweek, a temporary system was installed tosupplement supply while more work went

into creating something of a slightly morepermanent type of temporary system. Byearly February a workable solution was inplace and the town had a secure supply ofsafe drinking water.

Since installation the system hassuccessfully treated water of up to 2500 ntuto well within WHO Guidelines forDrinking Water Quality. Twice the townhas been flooded and buried by mud slides,which has impacted on supplies to othertowns in Gippsland Waters areadownstream on the Macalister River. Thelessons learned helping the community ofLicola, proved invaluable in helpingGippsland Water prepare their downstreamwater treatment plants for possible dirtywater events after rain.

This report outlines in brief, the process ofdetermining a suitable chemical dosingregime, and problems encountered inachieving a suitable water quality from thesystem.

Which Coagulant?

Several samples were collected so thatdifferent turbidity raw water could betested for flocculation and settling. Toensure simplicity of the process, a ‘singlechemical’ dosing option was preferred,since no trained water treatment personnelwere available to operate the system. Severalreadily available chemicals were trialledincluding; Polymer 1190, Alum,PolyAluminiumChloride and Aquapac55.

Polymer 1190 was trialled and found to beunsuitable as a coagulant/flocculant

W A T E R T R E A T M E N T

IN AT THE DEEP END!Mark Samblebe

Judged Best Overall Paper at WIOA’s Victorian Water Industry Engineers and Operators Conference 2007

Figure 1. Jar test results for Polymer 1190.

Figure 2. Jar test results for Alum.


reducing turbidity as seen in Figure 1,where optimal dose only resulted in settledwater turbidities of around 160 ntu.

Alum was then dosed in conjunction with1190 (at 5ppm which showed best resultsin first trial) showing improved results asseen in Figure 2. Settled water turbidity wasreduced to 50ntu. To improve performancefurther, pH correction was required, andwas rejected due to increasing complexity ofthe process. The fairly narrow workingrange also made this option less attractive.

Aquapac55 was tested and showed muchimproved results. Figure 3 shows settledwater turbidities of 17ntu at the optimaldose rates, which would be expected toimprove in the actual application due to theextra settling time that will be available onsite. 45 and 50ppm/v were the optimal doserates.

The best chemical for flocculation provedto be PAC10LB (10%PolyAluminiumChloride – Low Basicity) asshown in Figure 4. Results of jar tests usingPAC10LB gave excellent results with a verybroad working range which suited theapplication and experience of operatorslikely to manage the system once installed.Settled water turbidity of less than 2ntuwere achieved.

The ability of PAC10LB to produce flocover such a wide range of dose rates wasseen as being ideal to ensure successfuloperation of the system. All other chemicalsnot only produced higher settled waterturbidities, but also had a narrower workingrange which increased the level of expertiseand control operators would need to haveto keep the system working, especiallywhere raw water turbidities varied so widelyin such short time frames.

Putting It Into Practice

Based on results of the jar testing, thechemical selection was complete, now thesystem had to be set up. A dosing pumpwas sized and scavenged from within

Gippsland Waters spares. PAC10LB wasordered in small 15L containers to removethe need to install chemical storages andbulk loading/unloading facilities. SinceLicola is a small town with relatively lowdemand, one 15L container was calculatedto last between 3 and 9 days depending onthe raw water quality. A flow meter wasordered to determine the flow rate to allowcalculation of dose rates.

The concept for the system was starting totake shape. The swimming pool wasmodified by the addition of three plasticbaffles to maximise sludge retention andminimise sludge migration through thepool. The baffles also prevented shortcircuiting. Figures 5 & 6 show thetemporary baffles being installed by Lionsclub volunteers and Gippsland Water staff,and the Macalister River running at a“thick” 4000 ntu.

Chemical dosing systems were set up withrapid mixing provided by a half cockedvalve and bends in the pipe work. Whenthe plant was started, slow mixing wasinsufficient to encourage good flocformation which reduced the efficiency ofthe process. It was decided to operate thepool as a “batch” system, which operated infill and drain phases. This enabled the pool

more settling time to settle the fine floc.Generally the pool was filled during theafternoon, and allowed to settle overnight,then pumped out in the morning.

After a week of successful operation, the keyconcerns of staff were that sludge removalfrom the pool was very labour intensive. A“creepy crawly” pool vacuum was used toremove sludge periodically, howeverfrequently got caught on the plastic bafflesrendering it unsuitable for the job. Sludgehad to be manually removed via the poolvacuum system. This took a volunteer up toeight hours depending on the raw waterquality and how much sludge had beengenerated.

The second main issue, was an inability tomaintain a disinfection residual, despite thetreated water quality being below 1.5 ntu,higher organic loads were reducing a 2mg/L free chlorine residual to nearlynothing in the space of two hours. A fewphone calls were made and the team atActivated Carbon Technologies Pty Ltd,came to the party and donated, free ofcharge to the Lions Club, 3 months supplyof pre-wet Powdered Activated Carbon(PAC). All we needed to do was install aPAC batching/mixing tank and dosingsystem. Aeramix were contacted for helpwith the PAC mixing system, and provedagain that the water industry does have aheart, donating a mixer and a days labourto install and commission the PAC mixingand dosing system (Figure 7). Afterinstallation of the PAC dosing system,chlorine residuals increased and weremaintained into the reticulation system atsatisfactory levels.

In addition to this, we also needed to dealwith the sludge migration problem in theswimming pool clarifier! Aeramix donatedmore time to assist with construction of amore permanent solid baffle system as seenin Figure 8.

The solid baffles worked much better atkeeping sludge from migrating throughout


Figure 3. Aquapac55 jar test results.

Figure 4. PAC10LB jar test results.

the pool reducing the amount of time andeffort required to remove sludgesignificantly, as well as enabling the processto be run as a “flow through” rather than“batch” system clarifier.

Chemical mixing was improved by adding a200L container to the flocculation zoneinto which the inflow entered. This washalf filled with rocks to improve the rapidmix and spread or diffuse the flow tominimise short circuiting of the flocculationand settling zones and provide better slowmixing to aid floc formation at the inlet tothe flocculation area (Figure 7).

Conclusion

The town of Licola has had a torrid year in2007, surviving bushfire, re-establishing awater supply and distribution system,flooding and mudslides, and more recently,raging flood waters that saw the destructionof the roads and bridges that permit accessto the town.

Beyond the temporary system put togetherby Gippsland Water, Aeramix, ActivatedCarbon Technologies and of course theLions Club Volunteers, preliminary designand investigation into supply of a purposebuilt water treatment system wasundertaken. The water industry showedgreat support for this project providingmany discounts, and donations ofequipment and time.

The Lions club submitted an applicationfor funding to secure a safe water supply

and were awarded $100,000.00, but to datelittle progress has been made. Of theallocation to Licola for a water supply,much of this is being spent on consultancy,into the viability of supplying a shallowbore, and after it all the DSE do not intendfor the supply to be classified as potable,and it will not be plumbed into the townsreticulation. The Lions club, after all this,will most probably have to generate theirown funding to install a treatment plantregardless.

The challenges presented by bushfireaffected catchments for the potable waterindustry are wide and varied. This projectshows that even under the worst ofconditions, the bare essentials and basics ofwater treatment theory, if investigatedproperly and implemented with attention todetail to ensure the process chemistry

confined to a less than ideal physicalstructure can and does work.

Acknowledgements

In a project of this type, many organisationsand individuals deserve great thanks for theirassistance, with many more being worthy ofnote for their contribution to equipment fora permanent plant. Thanks to:

• Orica Chemicals Morwell - Scott Laidlaw– chemical supply and selection assistance.

• Activated Carbon Technologies Pty Ltd.– Peta Thiel and Peter Cullum - Supplyof 3 months PAC.

• Aeramix – Cole Harvey - Supply andinstallation of PAC mixing system andconstruction of baffles.

• Gippsland Water – supply of dosingpumps, tanks, process investigation andmaterials for baffle construction.

The Author

Mark Samblebe ([email protected]) is a Water TreatmentTechnologist with Gippsland Water inVictoria.



Figure 5. Temporary baffles in the Licolaswimming pool.

Figure 6. Macalister River at 4000ntu.

Figure 7. The PAC mixing system and ‘jerry rigged’ rapid mixing and diffuser tank.

Figure 8. The improved baffle system.

WaterWorksAdvertising

To reach the decision-makers in

the water field, consider

advertising in WaterWorks, the

official journal of Water Industry

Operators’ Association.

For information on advertising

rates, please contact Brian Rault

at Hallmark Editions,

Tel (03) 8534 5014 or email

[email protected]


COAGULANT DOSING CONTROLMOVES FORWARD

Chris Laidlow

C O A G U L A N T D O S I N G

Background

One of the main challenges for theoperators of a typical surface watertreatment plant is to achieve that‘optimum’ coagulant dose. This isparticularly important where the sourcewater quality varies considerably.

Over the years many attempts have beenmade at automating the process ofcoagulant control, arguably the mostsuccessful of these has been the StreamingCurrent Meter (SCM). SCM’s operate in afeed back control loop, takingmeasurements downstream of the coagulantdosing point and feeding information backto adjust the coagulant dose.

Past efforts at developing feed forward(predictive) control, based around eitherUV 254 or colour measurements, have beenlargely unsuccessful due to the very narrowrepresentation of removable contaminationthat these parameters reflect.

This article is a summary of the operationalimpacts that we have experienced with aunique feed forward system which was putinto service in 2006 at the WainuiomataWater Treatment Plant (WTP) inWellington, New Zealand. The new systempredicts the coagulant dose based on acombination of turbidity, UV254 andDissolved Organic Carbon (DOC)measurements.

The Wainuiomata WTP is a ‘run of river’plant which treats water from twocatchment areas to the north-east ofWellington. The catchments are bush cladand reserved solely for water supplypurposes. Raw water quality can changerapidly from very good (turbidity 0.5NTU, colour 5 deg Hazen and DOC 1.0mg/l) to very poor (turbidity > 500, colour

> 100 and DOC > 15 mg/l). Raw wateralkalinity is low at 16 mg/l (average) asCaCO3.

The treatment process can, to a certainextent, handle poor raw water conditionsbut the plant would normally be shutdownif the cost of treatment exceeds that ofother treatment sources.

The plant treats a maximum continuousflow of 50 MLD and the treatmentprocesses are; alkalinity addition and pHcontrol (lime and CO2), coagulation(PACl), polymer addition, flocculation,separation (DAF), filtration, pHadjustment and chlorination.

In 2005 we replaced our old colour meterswith s::can spectrophotometers. The s::canrecords the UV Vis absorption spectrumbetween 200 and 750 nm. These spectraare used to determine a range of parametersincluding DOC, TOC, UV254, colour andturbidity.

Figure 1 shows the raw water absorptionprofile from the Wainuiomata WTP inletover a 7 day period. The profile shows twoshort-term rain events during days 3 and 7.It can be seen that there is very little changein absorption in the colour range (375nm –

435nm) but a significant increase in theDOC range (250nm - 350nm).

Coagulant dose at the plant was controlledby an SCM. Whilst the SCM could berelied upon to cope with minor/moderateraw water quality fluctuations it did have itslimitations. pH variations affected the SCMoutput and, as the SCM control is afeedback system, it often failed to respondquickly enough or completely enough tosharp changes in raw water quality, thusleading to filter turbidity problems due tounder dosing.

During moderate to heavy rainfall the plantoperators had to keep an eye on filteredwater quality for signs of deterioration andwhen faced with an unfavourable weatherforecast they would often adjust the SCMset point to increase the coagulant dose inorder to pre-empt raw water qualitychanges. Since the price of under dosingwould be a six hour call out to wash all thefilters and get the plant back on line, thetendency was to play safe and overdose.

The SCM was also slow to react toimproving water conditions and theresulting dose often over or under theoptimum dose. This is clearly illustrated inFigure 2 which shows actual trends of the

Figure 1. UV Absorption Profile at Wainuiomata WTP.


dose controlled by the SCM compared withthe dose predicted by the feed forwardsystem.

Feed Forward Control System

In 2006 Dr Jason Colton of h2opeControlsLtd developed a coagulant control systemthat uses data from the plant inlet s::canand turbidity meter to derive a coagulantdose set point which, with the plant inletflow, is used to control the speed and strokeof the coagulant dose pump.

We installed the control system into theplant PLC in August 2006 and the planthas been running continuously on thissystem since then.

For a few days after installing the feedforward system we stayed on SCM controland compared the output of both systems.The first thing that struck us was theinstantaneous reaction of the feed forwardsystem to raw water quality variations. Itwas also noticeable how the feed forwardcontrol tracks the variations in a muchtighter fashion than the SCM output.

The feed forward system can operate in twomodes; conventional mode and enhancedmode. In conventional mode the feedforward algorithm optimises coagulantdosing for economy, which means that itwill calculate the minimum dose requiredto achieve acceptable filter outlet turbidityand run times. In enhanced mode thealgorithm optimises for DOC removal,which means that it will calculate theminimum dose required to achievemaximum DOC removal.

The feed forward system at WainuiomataWTP has now been in service for over 9months and over that time we have seen asignificant reduction in plant outages dueto ‘front end’ dosing problems.

By operating in conventional mode we have

reduced our coagulant costs by 15%. When

trialling the plant in enhanced mode, the

coagulant dose increased by about 10%,

however, due to the reduced organic load in

the filtered water, the chlorine demand

dropped by almost 15%.

The plant technicians have now gainedconfidence with the s::can and the feedforward system and pay it little attentionapart from checking the trend screens onthe plant SCADA. We are currentlyinvestigating ways to connecting the outputof the s::can to our SCADA network sothat the units can be accessed remotely.

As the s::can measures turbidity, we had itin mind that we could dispense with theraw water turbidity meter as well as thecolour meter and the SCM, but we have yetto resolve discrepancies between theexisting turbidity meter and the s::canturbidity measurement. We suspect that thecause of the discrepancy is due to airbubbles in the s::can sample chamber andwill be trialling a modified sample chamberin the near future.

The instrument display is situated in an IP65 enclosure which is mounted adjacent tothe probe (Figure 3).

This unit has a touch screen display fromwhich the operator can select variousdisplays, including the current value of eachparameter, historic trending and viewing ofthe raw spectral data which shows a


Figure 2. Comparison of Feedback and Feed Forward Coagulant Dose (Courtesy ofh2ope Controls Ltd, Wellington, New Zealand).


fingerprint of the water at that moment intime.

We had some initial issues with makingsure that the instrument was properly‘zeroed’ and discovered that it is importantto use water that is free of organics. We usedistilled water that has been passed througha mixed bed ion exchange resin.

The instrument probe sits in a samplechamber, essentially just a piece of PVCpipe, to which a raw water sample isconnected (Figure 3). The only connectionsto the probe are a small diameter air purgeconnection for automatic cleaning, and acable to connect it to the touch screendisplay.

Unlike our old colour and streamingcurrent meters, the s::can is a very robustpiece of equipment. It has no moving partsand pre-filtration of the sample flow is notneeded as the system can measure andcompensate for solids. The instrument hasan air cleaning cycle that can be controlledfrom the touch screen.

From a maintenance point of view it hasbeen trouble free and requires littleattention. The units are inspected weeklywhen the sample chamber drain plug isremoved to clear any accumulatedsediment. In addition to that, we carry outa monthly zero check.

In financial terms the investment in newinstrumentation and process controltechnology has netted immediate savings inthe order of $50,000 per year from reducedchemical use, maintenance and unscheduledplant shutdowns. In addition there will be a

favourable long term impact on the capitalreplacement, operations and maintenancebudgets as we will ultimately have the s::canreplacing three instruments; colour,turbidity and streaming current.

The broader benefits of improved waterquality are harder to define at this stage butwe expect to see a reducing trend in

organically derived compounds (taste &

odour & DBP’s) in the distribution system

over time.

Operator confidence, easing those nagging

doubts, is also difficult to define but it is

pleasing to see high levels of interest for the

new technology among our staff.

The combination of new instrumentation

and process control has been very successful

and the bottom line results speak for

themselves. We expect to see even greater

savings after installing the control system at

our other surface water treatment plant later

in the year.

Acknowledgements

I would like to thank Alastair Forsyth

(Wainuiomata Treatment Technician) for

his advice and clarification, Jason Colton

(H2ope Controls) and Rob Dexter (DCM

Process Controls) for assistance with

implementation of the technology.

The Author

Chris Laidlow ([email protected])

is Water Supply (Operations) Manager,

Greater Wellington Water in New Zealand.

Note: H2ope Controls are now marketing this

patented coagulant control system by the name

of Com::pass (ed)


Figure 4. S::can Parameters and Measuring Principals (Courtesy of s::canMesstechnik GmbH, Vienna, Austria).

Figure 3. The s::can unit is shown mounted against the right hand wall with theoutput display touch screen situated above it on the back wall. The old colour meteris shown on the left on the back wall.

The Molendinar Water Treatment Plant

(WTP) is one of two plants supplying

water to the Gold Coast. Figure 1 shows

the turbidity of finished water produced at

the Molendinar WTP for the period July

1999 to April 2007.

The graph clearly shows a dramatic

improvement in the quality of water

supplied to the Gold Coast. What has

brought about this improvement?

There have a been a number of key events

in the journey from relatively high and

variable filtered water quality to low and

consistent filtered water quality.

HACCP

A HACCP quality control philosophy was

introduced in 2000. This introduced Gold

Coast Water (GCW) to the concepts of

control points and monitoring of control

points and the identification of poor

performing points and formed a basis of

implementing improvement strategies.

Water Treatment Alliance

GCW joined the Water TreatmentAlliance in 2002. The WTA is a self

W A T E R T R E A T M E N T P L A N T S

GOLD COAST WATER IMPROVES Craig Bolin

Figure 1. Long term turbidity trend of finished water from the Molendinar WTP from1999 to 2007.

• Membrane keypads and LED digital

displays for programming of mixing and

flocculation times & speeds

• Independent microprocessors with Hall

Effect speed controllers

• LED lighting to illuminate floc, reduce

heat & improve safety

• Square Jars to emulate full scale water

plant conditions

• Paddles induce partial axial flow

• Quiet operation

• Compliance EN61000 FCC Part 15,

AS/NZS CISPR11, UL1950, CE.

Visit www.microfloc.com.au for more information

The Australian designed and manufactured microFLOC jar-testers provide many

world class features


improvement program for the optimisation

of WTP operation. The WTA introduced

the concept of extensive monitoring of

filtered water turbidity as a measure of total

WTP performance and the key role of

filters in achieving consistent low turbidity.

Filters after all are the only barrier to

protozoan pathogens and must be

optimised at all times. As a result GCW

started to collect more extensive filtered

water turbidity data.

Filter Upgrades

Both the HACCP and WTA programs

heightened our awareness of filters and

their key role as barriers to pathogens in

water treatment. Detailed inspection of the

filters quickly identified the need for a filter

rebuild. Figure 2 shows the state of the

filters at GCW’s other plant Mudgeeraba

WTP in 2003 where a thick layer of mud

covered most of the surface of the filter and

filter performance was at best marginal.

A complete upgrade was carried out from

the base up on the 16 filters at Mudgeeraba

WTP with the underdrains replaced and

the media upgraded from mono to dual

media.

The filters at Molendinar WTP were

upgraded from the nozzles up and also dual

media.

ADWG 2004

The “Framework for the Management of

Drinking Water Quality” incorporated in

the “Australian Drinking Water Guidelines

2004” concentrates on a risk management

approach to the management of drinking

water supplies. This approach was

completely compatible with the HACCP

program and the principles of the WTA

and extended our knowledge of this risk

management approach to water quality.

Operator Training

The Framework emphasises the importance

of operator training.

Operations staff are encouraged by GCW

to gain Certificate 3 in water industry

operations qualifications and dual ticket

competencies are looked upon favourably.

In addition, the majority of GCW water

treatment operations staff participated in

specialist “Filter Assessment and

Optimisation” courses offered by the WTA.

As part of these courses operators were

introduced to the responsibilities of GCW

and their own responsibilities with respect

to water quality. Simply stated,

Water Authorities have a responsibility to:

• Produce safe drinking water at all times

• Produce the best quality water possiblefrom the existing system.

Operators have a responsibility to ensure:

• Their actions do not compromise theproduction of safe drinking water at anytime.

• They actively provide feedback tomanagement when they are aware ofshortcomings in the treatment sequence

that may contribute to the production ofunsafe drinking water.

• They are alert to changes in the system

they operate within.

• They act to produce water that is

aesthetically pleasing.

Clearly staff training and awareness is a

high priority. It needs to be remembered

though, that in order to be effective,

training should not be confined to a one off

event. Ongoing training is required to

maintain the awareness needed to ensure

staff are aware of the relevant operational

and management issues and can respond

competently in the event of a water quality

incident.

Optimisation of Filter Function

Currently both of GCWs water treatment

plants have adopted the philosophy

described in “The Practical Guide to the

Operation and Optimisation of Media

Filters” (Mosse and Murray 2006) with the

view to achieving the longest possible

service life from the filters as well as

discovering any potential problems before

major rectification is needed and above all

else consistently produce the best quality

drinking water possible.

With the staff trained appropriately and theexisting equipment operating at optimum,forward planning can be carried out toupgrade the existing equipment orintroduce new and/or improved treatmentmethods.


Figure 3. Cumulative probability graphs for the finished water turbidity from theMolendinar WTP from 2002 through 2007.

Figure 2. The surface of one of the sandfilters at the Mudgeeraba WTP in 2003prior to a rebuild. Note the extensivethick layer of mud on the surface.


Replacement of Hydrated Lime withLiquid Sodium Hydroxide

The use of hydrated lime for post pHcorrection results in an increase inturbidity. While this does not represent anincreased risk to consumers, GCW saw anopportunity to improve water quality evenfurther and replaced the lime system with aliquid sodium hydroxide system with theadded benefit of a major improvement inthe physical working conditions in thisarea.

Replacement of Gas Chlorine withHypo

One additional improvement was that thechlorine gas disinfection system wasreplaced with sodium hypochlorite. Whilstproviding minimal impact on productturbidity and more expensive, the hypoeliminated high risk WH&S issues andprovided improved low range manganeseoxidization – this was appreciated byoperational staff.

Long Term Records

The importance of keeping long termrecords as well as operator training andawareness, having an improvement strategyin place and a firm commitment frommanagement is demonstrated in the aboveinformation and also provides the ability toshowcase the organisation’s operation.

Recently the Water Treatment Alliance hasdeveloped a database to store and report onlong term turbidity data submitted byparticipating water authorities with theview to creating a benchmark forcomparison of individual plantperformance. This system has beenoperating in the USA since the Milwaukeewater quality event in 1993 where 400,000people became ill drinking poorly treatedwater. GCW has recently submitted data tothe WTA. Figure 3 shows what are calledcumulative probability graphs for thefinished water turbidity from theMolendinar WTP from 2002 through2007.

The cumulative probability graphs showthe performance of the individualplants/filters against the performance of allthe US surface water WTPs participating inthe Partnership for Safe Water (The USequivalent of the WTA). The yellow anddark blue lines are the monthly maximumand monthly 95%ile performance for theUS plants. These graphs show thatapproximately 98% of the monthly 95%ileturbidity results reported by all the plantswere less than 0.2 NTU. Similarly 96% of

the monthly maximum turbidity valueswere less than 0.3 NTU.

A simple way to interpret the graphs is thatif the line for a filter is above those for theUS plants, then the filter is producingwater with a higher turbidity than themaximum monthly values recorded by allthe US plants. If the line for a filter isbetween the maximum and 95%ile plots forthe US plants then the filter is producingwater with a turbidity lower than themaximum monthly values recorded by theUS plants but higher than the monthly95%ile values. If the line is below the95%ile line for the US plants then the filteris producing water with a turbidity lowerthan both the maximum monthly and95%ile monthly values and can beconsidered to be performing moreefficiently. The lower the line the better theperformance of the filters.

Clearly the Molendinar WTP started off in2003 producing water of relatively poorquality. Over the years as a result of all theevents described above, there is a clearimprovement to the current situation in2007. The strength of this type ofmonitoring is also apparent in that it clearlyshows the drop in performance in 2005-06and the dramatic improvement in 2006-07.This was due to experimenting withdifferent polymers during a period whilstthe plant was experiencing shortened filterruns due to excessive head loss after achange in raw water quality. Traditionallynon-ionic polymer had performed best atMolendinar WTP and did so during thisperiod in regard to turbidity however at theexpense of shortened filter runs due to highhead loss. Cationic polymer improved thefilter head loss performance but resulted in

poorer turbidity in the filtered water. It wasdecided to put up with the shorter filterruns and keep the turbidity as low aspossible (<0.1NTU) until the raw watercharacteristics improved as occurred aroundFebruary “06”

Benchmarking offered by this type of longterm monitoring data naturally creates aform of competition between participantsand therefore adds weight to anyCAPEX/OPEX requests for new andimproved methods/equipment for theprovision of drinking water to theircustomers.

In providing a benchmark figure, theopportunity exists for an authority todisplay its product to the general user sothey have an understanding of the valuethey are receiving each time they pay theirwater account and increases theirconfidence in using its service.

Understandably budget constraints andresources impact on the time it takes toimplement improvements to any system,therefore it is recommended a long termplan be put in place.

Logically, the first place to direct the focusis to the existing equipment and resourcesthat are already in place. This is animportant message in the principles of theWTA and in the Mosse and Murray (2006)book. Apart from the infrastructure, themost important asset an authority has is itsstaff, after all there are not many systemsout there that operate without humaninput.

The long term data show that it can bedone and the importance of actually havingthe data to show that improvement. Ifanyone needs encouragement to start have alook at the state of our filters and thequality of our water in early 2000 and seewhere we are now. There are still things tobe done but GCW is confident it is nowproviding the residents and tourists to theGold Coast with much safer water nowthan we were then.

Acknowledgements

Peter Mosse, John Jacobs, Stan Stevensonand Nigel Garson for their assistance inpreparing this article

The Author

Craig Bolin is Recycled Water TreatmentPlant Supervisor at Gold Coast Water. He can be contacted on([email protected]). Craig iscurrently part of a team preparing tocommission a new class A+ Recycled WaterTreatment facility at Pimpama on thenorthern Gold Coast.


WaterWorksAdvertising

To reach the decision-makers in

the water field, consider

advertising in WaterWorks, the

official journal of Water Industry

Operators’ Association.

For information on advertising

rates, please contact Brian Rault

at Hallmark Editions,

Tel (03) 8534 5014 or email

[email protected]

Water Works December 2007 - WIOAwioa.org.au › documents › waterworks ›...

Documents

Transcript of Water Works December 2007 - WIOAwioa.org.au › documents › waterworks ›...