ACHIEVING THE BLUE DROPA City of Cape Town Perspective
CONTENTSOverview of City of Cape Town Water Supply SystemChallengesAdopted Elements of Best PracticeWater Safety PlanningBlue Drop AssessmentsConclusions
BULK SUPPLY SYSTEMThe City’s Bulk Water Supply Systemis planned and operated as anintegrated system;Integrated operation: (CoCT BW &WCWSS);Maximisation of the storage in theWCWSS for both the urban andagricultural demands throughminimizing spillage from the dams;The water resource planning,development and operation of theWCWSS is done by the City inconjunction with DWA and the otherusers.
BULK WATER SYSTEMPROFILEThe Western Cape Water Supply System:Supplied from 14 Damso Capacity of 6 major dams is 898 300 000 m 3ooo11 owned and operated by the City2 owned and operated by the DWA1 owned by TCTA and operated by DWA;12 Water Treatment Plants;oTotal treatment capacity of 1 600 Ml/d26 Bulk Reservoirs;oTotal storage capacity of 2 740 MlAtlantis Groundwater Scheme – artificiallyrechargedLarge diameter bulk conveyance pipelines –o605 km of up to 2.4m diameter pipelinesReticulation system > 10 000 kms with 256reservoirs and Distribution points in formaland informal settlements.Current City Demand ≈ 340 million m 3 pa;
CHALLENGESRaw water quality - cost of treatment of potable water.ooAlgal proliferation in dams impacts treatment - taste, odour and toxins e.g. (TWK, VV)Colour, soft, acidic, aluminiumMonitoring Capacity & Capabilityoo80% vs 100% SANS 241 determinands (Antimony, Cadmium, Selenium and Uranium)Sampling points in informal settlements, quality and reliability of resultsAvailability of suitably trained staff to meet DWA RegsoProcess controllers - RPLMaintaining acceptable DWQ throughout extensive integrated retic systemodisinfection challengeo Stabilization challenge – CO 2Aging infrastructureoAsset management plan
ADOPTED ELEMENTS OF “BEST PRACTICE”ISO SystemsCatchment Management – Drinking Water ResourcesDWQ Monitoring – In house Accredited LaboratoryTraining – PCs, SamplersTaste, Odour and Toxin ControlChemical Usage in Treatment ProcessesDisinfection & StabilizationIncident Management ProtocolAsset ManagementWater Safety Planning
IMPLEMENTATION OF ISO 9001 QMSBegan with Bulk Water ISO 9001: 2000 QMS certification in 2003Re-certification and roll-out to entire W & S DepartmentEnables a controlled environment for quality management andcontinual improvementStructured approachElectronic Document Management System
CATCHMENT MANAGEMENTPristine resourcesManage the catchmentsLimit human activity – detrimental toWQContain nutrients and contaminants toacceptable levelsControl vegetation – removal of alienspeciesMonitor raw water quality in thestreams and damsHydrobiologyo Algae counto Geosmin/MIBo MicrocystinRaw Water Quality – Treatment Cost
DRINKING WATER QUALITY REQUIREMENTSRisk Assessment of Water Safety plan is mainly based oncompliance of Drinking Water Quality.SANS 241 requires tests to be performed throughout the entirevalue chain of Water SupplyDevelopment of Sampling frequency and protocol is based on theoutcome of the test performedPopulation sampling coverage is defined as 1:20 000 for Metros
WATER QUALITY MONITORINGDWQ ChallengesSampling Coverage cannot be defined through water supplysystem since the entire system is INTEGRATED.Shortage of sampling point to cover the required ratio of 1:20 000identified in 2010 during the assessment.Capacity to ensure resampling within 24hrs as required by theCity‟s Incident Management Protocol
WATER QUALITY MONITORINGProgrammeMonitoring by In-house accredited laboratorySANAS Accredited in 2011High level of technical expertiseExtremely well equipped laboratory>110 000 phys, micro & chem analyses / yearMonitoring programmeHourly sampling and analysis – operational at WTP laboratorieso WTP Labs also well equippedWeekly composite and grab samples from WTP analysed at SSo Raw and treated waterWeekly sampling at reservoirs and distribution points – SSo Hand-held loggers – Sampling reliabilityWeekly Scientific Services visit by chemist to WTPMonitors processChecks plant labOversees equipment calibration
WATER QUALITY MONITORINGATLABSATLAB – Automated process lab at WTPsautomated pH, alkalinity, hardness, turbidity and residual chlorineanalysesgood repeatability, traceability and accuracygives trends of results for operational performanceconnected to central server – can view results from officeMonitor raw water quality in the streams and damsAlgae countGeosminToxins
WATER QUALITY MONITORINGBiological Sciences: HydrobiologyAlgal Monitoring &Identification, Chlorophyll-adeterminationThe section analyses water from various raw waterimpoundments eg. Theewaterskloof Dam, and Wetlands acrossthe city. Work is also done for a number of external clients. Staffalso contribute to over comments to clients w.r.t Physical,Chemical and algal monitoringSite investigations and Boat samplingBio-monitoringELISA Toxin tests for Microcystins
WATER QUALITY MONITORINGBiological Sciences: MicrobiologyMembrane Filtration and HPCMethodsThe section analyses water from Potable Water treatment plantsand Waste Water treatment plants. Test are also undertaken onwater in the various city wide reservoirs and distributionsystems, this includes the Informal settlements. Environmentalwater is also monitored monthly, these include rivers andwetlands as well as the fortnightly coastal waters, including Blueflag beaches.Cryptosporidium andGiardia trials areunder wayColilertMethod
WATER QUALITY MONITORINGScientific Services Laboratory ImprovementsHighest qualification (PHDs, Masters, Honours,Bachelors and Diplomas) in various watersciences and engineeringWater Quality Data maintained in LaboratoryInformation Management System (LIMS) whichwent live in July 2007.The city„s drinking water quality has consistentlyachieved position 1 in SABS inter-laboratorycomparison.SANAS: 17025 accreditation achieved in 2011.Legislation requires drinking water qualityanalyses be performed in an accreditedlaboratory.Many state of the art instruments - ICP, FIA, IC,TOC, UV, HPLC, ELISA (> R25 million) to attainbetter turnaround time on the high volume ofanalyses.
SAMPLER TRAININGThe correct procedure to collect samples isessential.SANS 241 Section 5.2 gives reference to theStandard Methods that can be used for asampling programme.Training of sampling officers and pollutioncontrol officers is critical in order to minimisecontamination associated with sampling. Intensetraining programme at the City.Samples need to be handled according to thelaboratory requirements in order to minimiseincorrect results. Strict SOPs in place.
PROCESS CONTROLLER TRAININGProcess specific trainingoPeculiar to the Cape soft, acidicand coloured watersSite specific trainingoPlant specific – different processesSpecialized on-site equipmenttrainingContinual updating.RPL – opportunity for olderexperienced hands with loweracademic levels
TASTE, ODOUR AND TOXIN CONTROLMonitoring protocolAnalysis(GCMS, ELISA)Powdered activated carbonCarefully selected to be effectivePAC dosing
CHEMICAL USAGE AT WTPsVery stringent specifications for processchemicalsMinimising contaminantsEnsuring sustained quality within tighttolerancesSecurity of supplyResulting in improved treated waterquality
CHEMICAL DOSING CONTROL AT WTPsState-of-the-art dosing control systemsChange from solid to liquid chemicalsMass-flow metering – Coriolis metersFeed the coagulant at precise rates (0.01 mg/l)automatically adjust according to:ooflow changeswater quality and temperature changesUV absorbance of coloured raw waterooa good measure of the required coagulantdosageSpectrophotometer used for rapid andsensitive determination UV absorbance
11 th International GothenburgSymposium8 th – 10 th November 2004Orlando, USASession 1: Dosage Control“Optimization of Potable Water Quality andChemical Usage through Specially DevelopedDosage Control Systemsin the City of Cape Town”byPeter FlowerISO 9001: 2000
Coagulation pH ControlWhen treating the coloured waters of the Cape, usingaluminium sulphate, selection of the optimum pH requires acompromise betweenMinimizing the residual organic contentminimizing aluminium concentration in the treated water.Generally the best organic removal is achieved around pH 5.2– 5.4But the solubility of aluminium increasesrapidly below pH 5,4Need to allow for a reasonable variationin pH, which is a practical reality in alltreatment plantsOptimum coagulation pH 5,6 – 5,8Because coagulation pH control is socritical to optimum flocculation andeffective colour removal, it was includedin the new control system.
Features of the Dosing Control SystemThe heart of the systema mass-flow metering device, (coriolis principle)to very accurately measureo masso densityo temperature of the product flowing through it.This measuring device is integrated with:An accurate dosing pump with a variablespeed drive,In-stream probes to monitor pH of thewater during coagulation,Spectrophotometer readings giving theUV Absorbance levels of the waterPLC-based computer system with feedback control loopsEnables extremely accurate:Dosing control and monitoring systemInventory control (not easily achieved when dealing with large volumes of liquiddosed at relatively low rates)Data Acquisition, Control and Reporting System (DACAR TM )Gives plant managers invaluable information to help optimise the processes tomaintain consistent high water quality with lowest possible chemicalconsumptions, etc.
Benefits Derived from the Improved SystemTypical Chemical DosingScreenCONTINUOUS ONLINE GRAPHICAL DISPLAY FOR PROCESS CONTROLA user-friendly and real-time display of process variables:Online process viewing – simple menu systemImmediate indication of deviation from set-points (pH & dosage mg/l accurate to 2 decimal places)Live trendingOnline monitoring of active chemical ingredientResulting in timeous implementation of corrective action – ensuring consistent qualityPower failure to pumps – current dosage rate (sec/litre) for manual operation
Benefits Derived from the Improved SystemMANAGEMENT REPORTSEffective management information(shift/day/month/ year) :Water treated and dosage trendsoAppears to vary, but reported to2 decimal placesChemical dosage precisionoActual vs targetpH control precisionoActual vs targetChemical mass-balance reportsoAccurate consumption reports andinventory controlStock leveloAlso expressed as “days stockremaining at current consumption”Cost & Performance:oooooChemical costsUnit process costsChemical savingsProcess efficiencyProcess Controller performance
Measured Effects and ImprovementsIMPROVED COAGULATION pH CONTROLEssential for effective coagulation and flocculation - achieved through:Closer monitoring with a continuous graphical display of the “Actual pH vsthe Target pH” – useful tool for process controllersAutomatic adjustment of lime dosing by linking motor speed of the screwfeed at the base of the silo proportionately to the plant flowDemonstrated by tighter groupingof plots – less scatterImproved Treated waterAluminium levels afterMay 2000May 2000
Measured Effects and ImprovementsREDUCED COAGULANT DOSAGE RATESRan trials to reduce coagulant ratesImproved consistency of concentrationEnhanced dosing control & monitoringReduced in 5% increments fromfactors determined empirically1st 5% ↓ for 2 months – system stabilityUV Abs of t/water closely monitoredMinimal affect recorded on treated UV2nd 5% reduction – achieved similar results, so a 3rd 5% reduction was made.Before trial 0.04 < UV Abs the City‟s upper limit of 0.1Reverted to 5% coagulant ↓ - conservative (lime feed automation, summer UV peak)Sodium aluminate dosed ∝ aluminium sulphate ∴ effective 5% sod alum reductionCoagulant usage ↓, quality ➚ , treated water Al, Na & SO4↓, roll-out plan.
Improvements in the Treated Water QualityREDUCED ALUMINIUM LEVELSImproved quality control as development processprogressed1st significant Al concentration reduction inSteenbras treated water:1995 – liquid Sodium Aluminate1996 – liquid Aluminium SulphateLower levels and improved consistency:Liquid coagulants – tight tolerancesDosing at accurately known and consistentconcentrationsTendency to o/dose – reduced.2nd significant Al concentration reduction:May 1999 – dosing control systemClear graphical indication of state of-, and changes in- the process with“on-line” trendingRapid and effective operator reaction“Finger trouble” largely eliminated – systemauto reacts to condition changes
DISINFECTION CONTROL AND MONITORINGPre-chlorination with dissolved gas used at the WTPs after the removalof the organics through effective flocculation and settlement to avoidTHM formationFinal chlorination at the exit from the WTP to the service reservoirRe-chlorination to ensure adequate residual through to the end of thereticulation systemChlorine residual monitored by means of on-line monitors, which areremotely monitored with alarms and trends recordedChlorine residual as well as microbiological indicators are monitored atstrategic points within and at the ends of the distribution systemSpecial sampling taps used to ensure reliable resultsSamplers undergo rigorous training and required to follow strict SOPs
DISINFECTION CONTROL AND MONITORINGDWA requires 0.2 mg/l chlorine residual as indication of “acceptable drinkingwater” in distribution system and point-of-deliveryCoCT aims to maintain bacteriologically safe drinking water -ofrequent analysis for E.coli and faecal coliforms together with themeasurement of free chlorine residual - “Best Practice”o Measure E.coli and faecal coliforms weekly - frequency >than SANS 241Residual Chlorine Levels - Not only rely on colorimetric comparator analysiso auto-titration equipment (AT-LAB by Metrohm TM )oon-line free chlorine analyzers (Micro 2000 TM ) at WTPs, bulk reservoiroutlets and distribution systemCity‟s bacteriological compliancePositive bacteriological measurement – at higher frequencyUse of technically sophisticated methods of Cl 2 monitoring and analysis,Question the need to exceed 0.2 mg/l chlorine residual at point of supply
STABILIZATION CHALLENGESoft, acidic coloured waterStabilization using lime and carbon dioxideNational shortage of carbon dioxideCompromising the stabilization processNeed to exceed the SANS 241 upper limit on pH to protect the infrastructure
DWQ INCIDENT MANAGEMENT PROTOCOLDeveloped a flow chart for the protocol to deal with failures of samplestaken of the treated water in terms of SANS 241 (Parts1&2): 2011oooFinal treated water at the WTPsAt the reservoir sampling points after secondary chlorinationAt the distribution sampling pointsProvides compact summary supplementing the detailed protocoldocument.On display at all Bulk installations for quick reference to:ooooRequired alert levelsResponse timesAction stepsContact details
DWQ INCIDENT MANAGEMENT PROTOCOL
DWQ INCIDENT MANAGEMENT PROTOCOL
DWQ INCIDENT MANAGEMENT PROTOCOL
THEEWATERSKLOOF DAMDAMSTABLE MOUNTAIN DAMSSTEENBRAS UPPER &LOWER DAMSWEMMERSHOEK DAM
WATER TREATMENT PLANTSSTEENBRAS WTP WEMMERSHOEK WTP VOËLVLEI WTPBLACKHEATH WTPFAURE WTP
RESERVOIRS, PIPELINES & PUMP STATIONSTYGERBERG RESERVOIRPLATTEKLOOF RESERVOIRFIRLANDS PUMP STATIONFAURE RESERVOIRWITSANDS PUMP STATIONVOËLVLEI PIPELINEVOËLVLEI PIPELINEVOËLVLEI PUMP STATION
ASSET MANAGEMENTThe City of Cape Town based its Asset Management Plan onthe International Infrastructure Management ManualUsed the Roger Byrne tool to inform the AMP (top-downlevel)Lower level of AMP on the SAP system still in progress(bottom-up)The whole system still needs to be fully integrated
ASSET MANAGEMENTOverall R.B.S Outputs for Bulk Water:Current Replacement Cost: R 12 779 mDepreciated Replacement Cost: R 5 818 mAnnual Planned Maintenance Required: R 40.1 mDRC/CRC: 45.3%R 4 000 000R 3 500 000R 3 000 000R 2 500 000R 2 000 000R 1 500 000R 1 000 000R 500 000R 0OPEX Repair profile in 2011Rands2011 2013 2015 2017 2019 2021 2023 2025 2027 2029R 300 000 000R 250 000 000R 200 000 000R 150 000 000R 100 000 000R 50 000 000CAPEX Repair profile in 2011RandsR 02011 2013 2015 2017 2019 2021 2023 2025 2027 2029
ASSET MANAGEMENTAsset Management Philosophy:Manage the considerable infrastructure assets through appropriatereplacement and maintenance programmes to ensure thesustainability of the bulk supply system.Maintenance is largely re-active with cyclic and pro-activemaintenance conducted on selected strategically important elementsof the infrastructure.A special form of asset management – very importantStabilization of the treated wateroooooRaw water highly corrosive and aggressive towards metals andcementicious materialsStabilize to just over a neutral point on the index – high pHFine film deposit on the pipes and fittings - protectionProvides protection to the Billions of Rands worth of infrastructureMaintains a sustained quality of treated water through the storage andconveyance system.o Stabilization level compromised by national shortage of CO 2oSANS 241 upper limit on pH
WATER SAFETY PLANNINGRisk-based approachWSP follows the WHO guidelines
WATER SAFETY PLANNINGCITY OF CAPE TOWN WATER SAFETY PLAN COMMITTEENAME DESIGNATION ROLE1. PHILEMON MASHOKO DIRECTOR: WATER & SANITATION Oversee Water QualitySafety Plan2. PETER FLOWER MANAGER: BULK WATER Chairperson, BD CommitteeStorage, Conveyance andtreatment of Bulk Water3. PIERRE MARITZ MANAGER: RETICULATION Distribution of DrinkingWater and Collection ofWastewater4. MPHARU HLOYI MANAGER: SCIENTIFIC SERVICES Water Quality Monitoringand Quality Assurance andBlue Drop Data Management5. JOSIAH MPOFU MANAGER: EAM Water and SanitationDepartment AssetManagement6. SAREL PIETERSE SECTION HEAD: WATER LAB, SCIENTIFIC Drinking Water SpecialistSERVICES7. ALF MOLL HEAD: OPERATIONAL LOGISTICS Drinking Water Protocoldevelopment8. MJIKISILE VULINDLU SECTION HEAD: BIOLOGICAL LAB, Drinking Water SpecialistSCIENTIFIC SERVICES9. JACO DE BRUYN HEAD: WS DEV PLANNING Information Management10. STEVIE DARK SPO: WATER LAB, SCIENTIFIC SERVICES Scientist11. ASA LEKKER / CARMEN JOHNSON PROFESSIONAL OFFICER: LIMS,Information ManagementSCIENTIFIC SERVICES12. DESIREE DAMON SECTION HEAD: QUALITY ASSURANCE, Quality AssuranceSCIENTIFIC SERVICES13. DOUGLAS KIEWIET ACTING AREA MANAGER: PLATTEKLOOF Process OperationsWTP14. ARNE SINGELS SPECIALIST: BULK WATER Bulk Water System specialist15. ZAMUXOLO TUTU MANAGER: MAINTENANCE Asset registers, Maintenance
CONCLUSIONS – LESSONS LEARNT
YEAR OFASSESSMENTBLUE DROP ASSESSMENTSNo OF ASSESSMENTCATEGORIESBD SCORE%COMMENT2009 9 100 One of only 3 municipalities toget 100%2010 9 98.18 2 nd highest Score2011 8 97.61 2 nd highest ScoreAlso received Platinum Awardfor 3 successive BD Awards2012 5 ? ???
BLUE & GREEN DROP ASSESSMENT PROGRAMSExcellent initiative on the part of DWA to focus institutions onwater quality managementLocal authorities – influence politicians to allocate fundingappropriatelyProvides an achievable goal for the staff in the Water &Sanitation industryRecognition of excellence is now possible.
Mpharu HloyiT: 021 684 1000M: 083 660 2300E: Mpharu.MoeletsiHloyi@capetown.gov.zaPeter FlowerT: 021 487 2586M: 083 375 0039E: Peter.Flower@capetown.gov.zaI thank you forQuestions? your attention