ThamesTunnel_

Report of the Thames Tunnel Commission October 2011


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1 EXECUTIVESUMMARY• TheThamesTunnelCommission(hereinreferredtoastheCommission)recognises

thatthescaleofsewagedischargesintotheThamesTidewayisunacceptable.Evenwiththeimprovementstothesewagetreatmentworks(STWs)andtheLeeTunnelinplace,theestimated18millioncubicmetresofannualstormwaterandsewageoverflowsandtheannualnumberofspillsfromcertainCombinedSewerOverflows(CSOs)wouldresultinadversewaterqualitythatwillintensifywithincreasesinthepopulationprojectedandwithpossibleadverseeffectsduetoclimatechange.

• ThetenworstCSOsareresponsiblefornearly80%ofthetotalloaddischarged.IfthesepollutingloadswereremovedthentheremainingCSOswouldnothaveasignificanteffectondissolvedoxygenintheRiverThames.Undercurrentplans,aproposed22kmlongtunnelwillcollectspillsfromtheseand7moreCSOsatacostforeachoverflowthatmightallowforindividualtreatmentworkstobebuiltateach.

• Thereisaneedtoaddresscurrentplanningandfundingarrangementsforwaterandwastewatersystems,asundertheseitiseasiertoconstructlarge,costly,inflexibleandenvironmentallyimpactinginfrastructuresystems,likethetunnel,thanitistoprovidegreeninfrastructurealternativesthatdelivermanybenefitstosocietyandthatareadaptabletoachangingclimate.

• WhiletheCommissionacceptstheneedtotakeintoaccountbothaestheticandhealthimpacts,thebenefitscomparedwiththecostsofconnectingtheproposednumberofCSOstoafulllengthtunnelneedstobere-assessed.

• ItiscruciallyimportantthattheEnvironmentAgency’smethodologyfordeterminingwhetheraCSOhasunacceptableadverseenvironmentalimpactsshouldbesupportedbyascientificallyrobustevidencebaseinformedbyadequatemonitoring,validatedcomputermodelsandmeasureswhichcanbepreciselycalculated.Giventhelackofscientificknowledgebehindthesemodelsandlimiteddata,uncertaintiesinthisassessmentprocessshouldbeclearlyidentifiedandlinkedtothecostsandbenefitsofremediatingeachCSOsothatinformeddecisionscanbemade.

• TheCommissionrecommendsthatawiderangingcost-benefitstudy,includingthefullrangeofpotentialbenefits,beundertakentoinvestigatethepotentialandfeasibilityofconnectingcertainlessfrequentdischargingCSOstogreeninfrastructuresourcecontrolmeasuresasanalternativetoconnectiontothefulllengthtunnel.GreaterattentionshouldbegiventoanassessmentofthedisproportionatecostsincurredincleaninguptheRiverThamestoachieveanunreasonablestandardofcleanlinesswheresalmonidfisheriesaresupported.

• TheCommissionregretsthatthealternativeoptionstoafulllengthtunnelhaveneverbeenadequatelytested,especiallywheresuchalternativescandelivermorethanthemono-benefitofCSOspillreductionthatthetunnelwillprovide.Theseoptionsincludereducingflowsbyseparation,bygreeninfrastructure,bytheconstructionoflocaldetachedsewagetreatmentworks,bytheconstructionofdistributedstorageandbytheenhancementoftheexistingseweragenetwork,therebyallowingapartialtunnelsolutionatalowercostorevenanon-tunnelsolution.

• ProfessorChrisBinnieandProfessorColinGreenhaveproducedproposalsforalternativesolutionsthatappeartooffermuchbettervalueformoneythanthesingletunnelsolution.TheCommissionurgesDefra,theEnvironmentAgencyandThamesWatertogivecarefulconsiderationtothesealternativeproposals.

TABLEOFCONTENTS 1 EXECUTIVESUMMARY

2 INTRODUCTION Page 5

2.1 HowtheThamesTunnelbecamethepreferredoption

2.2 Developmentssincethe2007MinisterialrequestfortheThamesTunnel

2.3 TheThamesTunnelCommission

3 SUMMARYOFEVIDENCERECEIVED Page 10

3.1 Interpretingcompliancerequirementsandotherdrivingfactors

3.2 EvaluatingcriteriausedtovalidateThamesTunnelanddetermineconnections

3.3 Questioningforconnectionsandverifyingmodelswithdatacollection

3.4 Estimatingcosts/benefitsandtheimpactonThamesWaterbillpayers

3.5 Understandingimplementationhurdlesofgreeninfrastructurealternatives

4 INVESTIGATIONOFALTERNATIVESOLUTIONS Page18

4.1 Greeninfrastructureoptions

4.2 EvidencefromUSCities

4.3 DeliveringmultiplebenefitsfromusingSustainableDrainageSystems(SuDS)andWaterSensitiveUrbanDesign(WSUD)

5 RECOMMENDATIONS Page24

5.1 Planningissues

5.2 Thecaseforthetunnel

5.3 Thecaseforamixedsolution

5.4 Theinfractionproceedings

MAPS Page32

Map1 PreferredAbbeyMillsroute

Map2 UnsatisfactoryCSOsfordissolvedoxygen

Map3 UnacceptableCSOsonhealthgrounds

Map4 CSOsplacedincategory2

APPENDIX Page36

AppendixA MembersoftheCommission

AppendixB Bibliography

AppendixC Writtenevidencereceived

AppendixD Oralevidencehearings

AppendixE Listofabbreviations


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2 INTRODUCTION2.1 HowdidtheThamesTunnelbecamethepreferredoption?

2.1.1 MuchofLondon’ssewerageinfrastructureconsistsofcombinedsystems,meaningasinglesewerconveysbothfoulsewageandrainwaterrunofftoasewagetreatmentworksfortreatment.Thecurrentsewersystemissubjecttosignificantflowsfromsurfacedrainage,whichhasintensifiedinthelastdecadesbecauseofincreasingamountsofimpermeablesurfacesthataccompanydevelopmentandaggravatestormwaterrunoff,aswellaspopulationgrowthandintensifiedweatherevents.Inparticular,theincreaseinhardsurfaces,suchasroofsandroads,hasreducedthecapacityofthelandtoabsorbrainwater.Instead,itonlytakesafewmillimetresofrainfalltosurgeintothecombinedseweragesystem.Whenthisoccurs,itisnormalpracticetodischargetheoverflowsofstormwaterandsewagedirectlytoawatercourse—or,inLondon’scase,intotheRiverThames.Thisiscalledacombinedseweroverflow(CSO)event.

2.1.2 In2000,theThamesTidewayStrategicStudy(TTSS)Groupwasestablished,undertheindependentchairmanshipofProfessorChrisBinnie,withrepresentativesfromthekeyUKgovernmentagenciesinvolvedinurbanwastewatermanagement:theEnvironmentAgency(EA),theDepartmentforEnvironment,Food,andRuralAffairs(Defra),theGreaterLondonAuthority(GLA),andThamesWater(TW).TheWaterServicesRegulationAuthority(Ofwat)maintainedanobserverstatus.TheobjectivesoftheTTSSweretoassesstheimpactofintermittentdischargesofstormsewageontheThamesTideway,toidentifyobjectivesforimprovements,andtoexplorepotentialsolutions.

2.1.3 Followingfouryearsofanalyses,theTTSSrecommendeditspreferredsolution:alargediameterstorageandtransfertunneltobedeliveredwithin15yearsknownastheThamesTidewayTunnel.Atotalof36combinedsewageoverflows(CSOs)wereidentifiedbytheEnvironmentAgencyasbeingunsatisfactory,ofwhich34dischargedintothetidalThamesandtwointotheRiverLee.Theremaining21CSOswerefoundbytheEAnottorequireanyaction.

2.1.4 ThelargestunsatisfactoryCSOdischargingintotheRiverLeewastobeaddressedbya7kilometrelong,7.2metrediameterstoragetunnel,referredtoastheLeeTunnel,fromAbbeyMillsPumpingStationstoBecktonSewageTreatmentWorks,whilealocalimprovementsolutionwasadequatefortheotherCSO.FollowingcompletionoftheimprovementstothesewagetreatmentworksandtheLeeTunnelby2015,bothunderwaynow,spillagesofcombinedstormwaterandsewagetothetidalThamesinatypicalyearareestimatedtobereducedfrom39millioncubicmetrestosome18millioncubicmetres,atatotalcostof£1.3bn.

2.1.5 TheThamesTunnelwastoaddresstheremainingspillagesandcriteriadevelopedbytheTTSS:

• Toreducetheadverseenvironmentalimpactsontheriverecosystemsandfishspecies;

• Toreducetheunacceptableaestheticissues,and;

• ToreducetheelevatedhealthrisksforrecreationalusersofthetidalThames.

AtthetimeoftheTTSSrecommendation,estimatedcostoftheThamesTunnelwas£1.7billion.

2.1.6 In2005,OfwatcommissionedareportbyJacobsBabtietoreviewtheworkandreportsoftheTTSS.PublishedinFebruary2006,itsuggestedaproposalthatprovidedlessbenefitsatalowercost:twoshortertunnelsintheeastandwest,anewtreatmentfacilitynearHeathwallPumpingStationincentralLondon,andascreeningplantandenhancedprimarytreatmentplantatAbbeyMillsineastLondon,aswellasin-riverskimmers,sewagetreatmentupgrades,andre-oxygenationmeasures.TheBabtiereportalsodidnotfullyagreewiththecriteriaset

• TheCommissionalsourgesconsiderationofcomplimentarygreeninfrastructuresolutionsinthemediumtolongtermtoalleviatestormwaterrunoffvolumesbeforetheyentertheseweragesystemandtoaddresssurfacefloodwaterchallenges,particularlyinthecontextofemergingnationalandEuropeanlegislationandpolicysuchas“TheNaturalChoice:SecuringtheValueofNature”,thatpromoteprinciplesofeconomicandenvironmentalsustainabilityandintegratedwatermanagementapproaches.

• TheCommissionraisesseriousconcernsabouttheescalatingcostsoftheThamesTunnelandtheimpactthiswillhaveoncustomers,pushingasignificantproportionofThamesWaterbillpayersintowaterpoverty.

• TheunderlyingprinciplesofnationalandEuropeanlegislationandpolicyemerginginthelastfiveyearsareeconomicandenvironmentalsustainabilityandanintegratedapproachtowatermanagement.ThisshouldlieattheheartoftheapproachtoreducingstormwaterandsewagedischargesintotheThamesTideway.

• TheNationalPolicyStatement(NPS)onWasteWatershouldnotpre-empttheroleoftheplanningprocesstodeterminewhethertheThamesTunnelmeetsthecriteriaformajorwastewaterdevelopments.TheCommissionsupportstheEFRACommittee’srecommendationthattheNPSshouldbesimplyagenericdocumentandnotmakereferencetospecificschemes.

• Overthepast10-15years,thefeasibilityofSuDSasasubstantialpartofthesolutiontotheproblemofurbanwatermanagementhaschangeddrastically.OthercitiesaroundtheworldprovidetheevidencethatthenewtechnologiesareoperationalandreliableandthatrapidimplementationofSuDSandGI–sayin10to20years–isrealistic.

• TheCommissionstronglyrecommendsthatthe2007MinisterialrequestofThamesWatertopursueafull-lengthstoragetunnelbereconsidered,sothatthefullrangeof‘besttechnicalknowledge’optionsavailabletomanagestormwaterareevaluatedwithequalconsiderationasthetunnelinmeetingcompliancewiththeUrbanWasteWaterTreatmentDirective.TheCommissionalsoencouragesDefratoinformtheEUproceedingsfortheneedforanenvironmentalandeconomicreassessmenttoensurethatnotonlystormwateroverflowissuesareaddressedbutalsofloodingandwidersocietalbenefits,andthattheoptionspursueddonotentailexcessivecostforthebenefitsaccruedintoday’seconomicclimate.


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usedtobenchmarkoptions,andthatitwillinevitablyincreaseatoutturnoncetheprojectriskandfinancingcostisaddedin.

2.2.4 InMarch2010,thethenSecretaryofStateforEnvironment,FoodandRuralAffairs,HilaryBenn,setoutthecasefortheThamesTunnelasaprojectofnationalsignificance,which,ifnotimplemented,couldcausereputationalrisktotheUK.ThesucceedingSecretaryofState,CarolineSpelman,issuedawrittenministerialstatementinSeptember2010confirmingtheCoalitionGovernment’ssupportfortheconstructionandwrotethat:“IamalsomindedthatdevelopmentconsentfortheprojectshouldbedealtwithundertheregimefornationallysignificantinfrastructureprojectsestablishedbythePlanningAct2009.Iconsiderthatthisprojectwithitsuniquescaleandcomplexity,isofnationalsignificanceand,therefore,appropriateforthisregime.”

2.2.5 In2010ThamesWateropenedanew£250milliondesalinationplantinEastBecktondesignedtoprovidewaterto1millionoftheCapital’spopulationduringtimesofdroughtandpeakdemand.TheCommissionreceivedevidencefromProfessorColinGreenmakinganeconomiccasethat,insteadofdesalination,stormwatercouldhavebeencollectedbysourcecontrolmeasures,suchasrainwaterharvestingaroundtheCity,savingtheneedforsuchanenergyintensiveplant.(See:http://www.lbhf.gov.uk/Directory/News/ttc.asp)Thisisanexampleofthepropensitytouselargeinfrastructuralsolutionsratherthandispersedandlocalisedapproachesasisdoneinmanyotherpartsoftheworld.InLondonthiswouldremovesignificantamountsofstormwaterandreducedemandforthesewertunnel.

2.2.6 ThamesWater’sphaseoneconsultationprocesswasconductedfromSeptember2010toJanuary2011.ThephasetwoconsultationprocessisduetobegininNovember2011.ThamesWaterexpecttosubmitplanningapplicationsinthesummerof2012.

2.2.7 Between2007and2011,severalkeylegislativeandpolicystatementsrelatedtowatermanagementhaveemergedbothintheEUandtheUKthatshouldalsoinformtheThamesTunnelimplementationdecisions.IntheEU,thesepolicydocumentsincludetheEUBiodiversityStrategy,theApril2009ECWhitePaper,‘AdaptingtoClimateChange’,andtheWaterFrameworkDirectiveGuidanceDocumentsonCommonImplementationStrategy.IntheUK,thesedocumentsincludetheUKGovernmentWhitePaper,‘TheNaturalChoice:Securingthevalueofnature’,andtheUKNationalEcosystemAssessment.

2.2.8 IntheEUBiodiversityStrategy,relevantpolicyincludesTarget2,whichsaysthat,by2020,ecosystemsandtheirservicesaretobemaintainedandenhancedbyestablishinggreeninfrastructureandbyrestoringatleast15percentofdegradedecosystems.Specifically:

• Action5:Improveknowledgeofecosystemsandtheirservices;

• Action6:Setprioritiestorestoreandpromotetheuseofgreeninfrastructure;

• Action7:Ensurenonetlossofbiodiversityandecosystemservices.

Action6goesontocommittheEuropeanCommissiontodevelopaGreenInfrastructureStrategyby2012topromotethedeploymentofgreeninfrastructureprojectsandthemaintenanceofecosystemservices,forexample,throughbettertargeteduseofEUfundingstreamsandPublicPrivatePartnerships.By2014,MemberStates,withtheassistanceoftheCommission,arechargedwithdevelopingastrategicframeworktosetprioritiesforecosystemrestorationatsub-national,nationalandEUlevels.On12thOctober2011,theMinister,RichardBenyonlaunchedthe‘GreenInfrastructurePartnership’,saying:“Thereareareaswherethereisn’tenoughgreenspacetofacethechallengesofclimatechange–increasedfloodingandoverheatingandthereareareaswherelackofgreenspaceisassociatedwithdeprivationandpoorhealth.”

outbytheTTSS,includingthedissolvedoxygentargetsfortheenvironmentalimpacts,andsuggestedthatsustainabledrainagesystems(SuDS)shouldbeimplementedoverthemediumtolong-termwhereappropriate.

2.1.7 TheTTSSandBabtiereportsandoptionswerethenconsideredbyaworkinggroupsetupbyDefrainDecember2005.Theworkofthisgroupwasinitiallytoconsiderwhetherapartialsolution,coherenttothewiderThamesTidewayproblem,couldbedeliveredintimetoprotectthe2012OlympicandParalympicGamesagainsttheriskofsignificantaestheticpollutionfromCSOs.ThisworkledtothethenMinisterofStateforClimateChangeandtheEnvironment[IanPearson]writingtoThamesWaterinJuly2006toaskittoprovideadetailedassessmentandcostsfortwooptions:option1beingafull-lengthandcontinuoustunnelcontrollingunsatisfactoryCSOsintheBecktonandCrossnesscatchments;andoption2beingtwoseparatetunnelsasproposedintheJacobsBabtiereport.

2.1.8 InDecember2006,ThamesWaterdelivereditsassessmentintheThamesTidewayTunnelandTreatmentSummaryReport,‘TacklingLondon’sSewerOverflows’.ItconcludedthatOption1variantsachievedahigherproportionoftheobjectivesdefinedbytheTTSSandthattheonlyvariantofOption1thatcouldrealisticallyofferanypotentialforthedesiredearly-phaseddeliveryforthe2012Olympicswasafull-length(30kilometre),7.2-meterdiametertunnelfromAbbeyMillsandWestLondonjoiningatBeckton—knownasOption1c(seeMap1)

2.1.9 Thisreportinformedthe‘RegulatoryImpactAssessment,2007’forsewagecollectionandtreatmentforLondon,publishedbyDefrainMarch2007.Specifically,theassessmentrejectedthesolutionintheJacobsBabtiereportbecauseitdidnotmeetthecriteriasetbytheTTSSandtheEnvironmentAgency(EA),andbecauseitwasconsiderednottomeettherequirementsoftheUrbanWasteWaterTreatmentDirective.Specificallytheproposalwasrejectedfornotdealingwithoverflowsfrom18unsatisfactoryCSOsandbecause,accordingtocomputermodelingresults,theexpectedimprovementofdissolvedoxygenconcentrationsdidnotmeettherequiredstandards.

2.2 Developmentssincethe2007MinisterialrequestfortheThamesTunnel

2.2.1 InApril2007,theMinisterofStateforClimateChangeandtheEnvironmentstated,inalettertotheChiefExecutiveofThamesWater,that:“Afull-lengthstoragetunnelwithadditionalsecondarytreatmentatBecktonsewagetreatmentworks…isneeded.”Subsequently,theMinisterrequestedthatThamesWatermakeprovisionforthedesign,construction,andmaintenanceofthescheme.Asaresult,Option1cfromtheTTSSreportbecamethebaselinetunneloptionconsideredbytheLondonTidewayTunnelprogrammeandhasremainedassuchsince.

2.2.2 Followingthisinstruction,ThamesWaterhasrefinedthefull-lengthstoragetunnelschemebyexaminingthreealternativetunnelalignments:theRiverThamesroute,theRotherhitheroute,andtheAbbeyMillsroute.AllthreecontributetowardsachievingtheEAwaterqualitystandardsandtheTTSScriteria,andsatisfyingtheinterpretedrequirementsoftheDirective,buttheAbbeyMillsrouteoffersthelowestcostandleastadverseenvironmentalandcommunityimpacts,soisnowthepreferredroute.Siteselectionconsultationwasconductedin2009.

2.2.3 Therecommendedfull-lengthstoragetunnel(AbbeyMillsroute)isnowestimatedtocost£3.588billionandhastheshortestimplementationtimetofacilitatetargetobjectivesin2020.ThamesWater’sNeedsReportconcludesthatcomparedtoothertunnelalternatives,thefull-lengthstoragetunnelapproachontheAbbeyMillsrouteisthemostcosteffectivesolutionwhichmeetstheDirectiverequirementsandtheenvironmentalobjectivessetbytheTTSS.InanarticleintheNewCivilEngineermagazineofJunethisyear,however,MartinBaggs,ThamesWater’sChiefExecutiveOfficer,revealedthatthe£3.6bnpricetagisanindicative2008price,


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contain“particularadvice”onalternativestotheLondonschemessuchasreducingdemand,divertingsurfacewaterfromsewagesystemsordecentralisationofwastewatertreatmentinfrastructure.Itarguedthat,sincepreviouslyrejectedalternativestotheThamesTunnelhadnowhadtheircostassessmentsrevised,itwasinappropriatetorestricttheIPC’sconsiderationof“plausiblealternatives”[121].TheMinisterconcededthattherecouldbea“bitmore”informationincludedontheneedforspecificprojectswhichwouldhelptheIPCfurther[123].”

2.3.2 TheconcernsoftheEFRACommittee,andthosewhosubmittedevidencetotheCommittee’sinquiryintotheNPS,madecleartheneedforanindependentreviewofthevariousoptionsfordealingwithLondon’swastewater,withinthewidercontextofwatermanagementacrosstheCapital.FiveLondonboroughs(HammersmithandFulham,KensingtonandChelsea,Richmond,SouthwarkandTowerHamlets)cametogethertosponsoranindependentCommissiontocarryoutthisreview.

2.3.3 TheaimandpurposeoftheThamesTunnelCommissionwasfourfold:

• ReviewthefindingsofpreviousstudiesrelatingtotheThamesTunnelandreassesstheassumptionsmadeinthosestudiesinthelightofsubsequentresearchandmoreup-to-datescientificknowledge;

• Examinetherecentresponsesofotherworldcitiestotheproblemsofpollution,floodingandpotentialwatershortages;

• Considerevidencefromstakeholders,expertsinthefieldandotherinterestedparties;

• ReassesstheoptionsforaddressingEUDirective91/271/ECinthelightofdevelopinginternationalperspectivesonwastewatermanagementandinthelightoftherecentEUWhitePaperonAdaptationandSurfaceWaterManagement.

2.3.4 TheCommissionmetregularly,overathreemonthperiod,toreviewtheexistinganalysesofwastewatermanagementinLondon,withinthecontextofcurrentandemergingenvironmentallegislation,policyandprocedures(seeAnnexB).TothatendtheCommissionstudiedpracticesandapproachesusedabroadaswellasnewdevelopmentinurbandrainage,wastewatercollectionandtreatment,sustainableurbandesignandredevelopment.Atotalof40organisationsandindividualssubmittedwrittenevidencetotheCommission(seeAnnexC)and,overthreedays,atotalof25individuals,representing12ofthoseorganisations(seeAnnexD),werecalledtogivefurtheroralevidencetotheCommission.

2.3.5 ThisreportpresentsthefindingsandrecommendationsoftheCommissiononthebasisoftheevidencereceived.ThemembershipoftheCommissionandmembersoftheSecretariatarelistedatAnnexA.

2.2.9 IntheECWhitePaper,‘AdaptingtoClimateChange:TowardsaEuropeanframeworkforaction’,underthewatermanagementsectionthereisacommitmentto“explorepossiblewaysofimprovingpoliciesanddevelopingmeasureswhichaddressbiodiversitylossandclimatechangeinanintegratedmannertofullyexploitco-benefitsandavoidecosystemfeedbacksthataccelerateglobalwarming.”

2.2.10 IntheWaterFrameworkDirectiveCommonImplementationStrategy,GuidanceDocumentNo.24says(underPrinciple7:Favouringrobustadaptationmeasures)that:“Ifinvestmentsarebeingplannedforinfrastructurewithlonglifespansitisprudenttofavourmeasuresthatareresilienttoawiderangeofplausibleclimateconditions…thesemeasuresshouldalsoworkwithnaturalprocessesandrealisemultiplebenefits(e.g.,forfloodriskmanagement,droughtmanagement,natureconservation,navigationandrecreation).”InPrinciple8:Maximisingcross-sectoralbenefitsandminimisingnegativeeffectsacrosssectors,itsaysthat“measurestakentoimprovewaterstatusthroughwastewatertreatmentorreuse,artificialrechargeofaquifers,inter-basintransfersandsoforth,implyhigherenergyconsumptionandgreenhousegasemissions.”

2.2.11 TheUKGovernmentNaturalEnvironmentWhitePaper,‘TheNaturalChoice;Securingthevalueofnature’(June2011),laysoutavisionto2060forbiodiversity,watermanagement,greeninfrastructure,airqualityandecosystemservices.Greeninfrastructureisexpectedtodeliverreducedpollutionandgreaterresiliencetoclimatechange.Thepaperoutlines10‘catchmentlevelpartnerships’betweenbusinesses,citizensandinterestgroupsandencourageslocalnaturepartnershipsworkingatthestrategiclandscapescale.TheWhitePapercallsformorecoherentandlargescaleapproachestoprotectfragmented,fragileecosystems;citinganeedtorestorenatureinourcities,townsandriversandrecognisingthetensioninwatermanagementbetweenincreaseddemandandreducedflowsinsummer.

2.2.12 The‘UKNationalEcosystemAssessment:Understandingnature’svaluetosociety’(June2011)notesthatecosystemshavechangedmarkedlyoverthepast60years,pressuresareincreasing,andthenaturalworldisconsistentlyundervalued.Itcautionsthatdecisionsmadenowwillhavefarreachingconsequencesandthatamoreintegrated,holisticapproachisneededtodeliversustainabledevelopment.Therecentlypublished‘ManualforCities:EcosystemServicesinUrbanManagement‘providesclearguidanceandevidencefortakingamulti-functionalandmulti-valueapproachtonaturalandgreenspacesinurbanareas,connectingurbanplanninganddesignwithecosystemsandwatermanagementinanintegratedway.

2.3 TheThamesTunnelCommission

2.3.1 TheThamesTunnelCommissionwaslaunchedon4July2011,informedbytheEFRACommittee’sresponsetoDefra’sdraftNationalPolicyStatementonWasteWater,whichhighlightedthelackofinformationavailabletotheCommitteeonalternativeoptionstotheThamesTunnel:

“TheabsenceofadetailedevidencebasemakesithardtoassesswhetherthedraftNPS’sconclusionsonthepotentialforSuDs(sustainabledrainagesystems)tocontributetoreducingwastewaterareeitheroverorunder-stated.WerecommendthatDefrarevisestheNationalPolicyStatement(NPS)tosetoutindetailthebasisofitsassessmentforthepotentialofalternativeapproachestomitigatetheneedfornewinfrastructure,suchastheincreaseduseofsustainabledrainagesystemsandwaterefficiencymeasurestoreducetheproductionofwastewater.”

Inparagraph64ofthereport,theCommitteefurthernotesthat:

“WitnessesalsohadreservationsastotheadequacyofthedraftNPS’ssectionsonalternativestoconstructingnewinfrastructure.LondonCouncilswereconcernedthatthedraftNPSdidnot


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providesolutionsassociatedwithresponsetotheUWWTDbyreducingstormwaterenteringthesewagesystem,obviatingthenecessityforatunnel.Inanearlystudy,ThamesWaterarenowworkinginpartnershipwithlocalauthoritiestoconsiderusingSuDStomanagefloodriskintheCountersCreeksewercatchmentarea.

3.1.6 Toasignificantextent,floodmanagementisunhelpfullyseenasaseparateissuetowatersupplyandwastewatertreatment,requiringdifferentandoftendisconnectedsolutions.Thesameistruefortheissueofwastewatertreatment.DevelopmentsinwastewatertreatmenttechnologycanbeofsignificantinfluenceonthelocationofSewageTreatmentWorks(STWs),onthepreferredmixofblackwaterandstormwater,onthetolerablehydraulicloadinganditsvariability,ontheusabilityoftheeffluentandmuchelse.Incontrastwithmanymajorcitiesaroundtheworld,anintegratedmasterplanforthedrainage,floodriskmanagement,watermanagement,waterqualitymanagementandwatersupplyofMetropolitanLondonislacking,asistheintegrationofthesewaterissueswithpoliciesonurbanplanning,socialandeconomicdevelopment,publichealthandwell-being.

3.2 EvaluatingthecriteriausedtovalidatetheThamesTunnelanddetermineconnections

3.2.1 TheTTSScriteriasettoevaluatetunneloptionswerethreefold:

• Toreducetheadverseenvironmentalimpactsontheriverecosystemsandfishspecies;

• Toreducetheunacceptableaestheticissues,and;

• ToreducetheelevatedhealthrisksforrecreationalusersofthetidalThames.

3.2.2 AccordingtotheTTSSreport,“therearenostatutoryecologicalobjectivestoapply”and“sinceitisgenerallyrecognisedthatfisharethemostsensitiveindicatorofecologicalquality,thedecisionwastakentodevisestandardsthatareprotectiveofrelevantfishspecies.”(16)(S4:ProtectionofEcology:paras2and3).Alargenumberoffishare,however,alreadypresent:125differentspeciesoffishhavebeencaughtintheThamesEstuarybetweenFulhamandTilburysince1964.Since1990,13newspecieshavebeenrecordedintheRiverThames,includingseahorses,afterearlierinvestmentinsewerageinfrastructuretoimproveriverquality.

3.2.3 TheecologicalstandardsdevisedbytheTTSSGroupweremuchmoreambitious,withtheaimofturningtheThamesintoasustainablefisheryforsalmon,smeltandothersensitivespecies(9)(S5.12–5.15).ThereseemstobenolimittothebudgetthatcanbespenttosustaintheThamesasafisheryforsensitivefish.UWWTDandUKRegulationsdonotlegislateforit,however,andtheCommission’sviewisthatthisaimisexpensiveandunrealistic.

3.2.4 TheWandsworthSocietyquestionstherationalefortheproposedtunnel,believingitwillhavearelativelylimitedeffectonthequalityofwaterinthetidewayatahugeenvironmental,socialandfinancialcost.TheSocietygoesontociteseveralkeystudies,includingJacobsBabtie,whichstatesthattheSTWupgradeswouldpreventmostfishkills.EvidencefromtheEAtotheCommissionprovidedlittlescientificandcredibleinformationabouttherelativeamountsofoxygenandbacteriologicalpollutionarisingfromtheCSOspills,STWinputs(frombothstormtankoverflowsandfinaleffluents),backgrounddiffuserunofffromroadsandothersurfacesintheCityandcomingfromupstreamintotheriverreachaboveMogden.Itispossiblethatevenwiththeproposedtunnel,pollutionfromthesemyriadofothersourceswillstillcompromisethequalityoftheriverwater.

3.2.5 ThewaterintheRiverThamesisusedforalargenumberoffunctions,inadditiontotheecologicalfunctionsthatitservesanditistheconvictionoftheCommissionthatthewatercouldbeusedevenmoreintensively.Waterqualityrequirementsfortheseotherfunctionswereneverelaboratedon.Thatmakesthefocusofthewaterqualitystandardsratherlimited,

3. SUMMARYOFEVIDENCERECEIVED3.1 Interpretingcompliancerequirements&otherdrivingfactorsforthe

ThamesTunnel

3.1.1 TheneedfortheThamesTunnelarises,inlargepart,fromtheobjectiveoftheUnitedKingdomtoaddressinfractionproceedings,takenagainsttheUKbytheEuropeanCommissionforbeinginbreachoftheUrbanWasteWaterTreatmentDirective(91/271/EEC).IntheopinionoftheEuropeanCommission,wastewatercollectingsystemsinLondonarebeingallowedtospilluntreatedwastewatersfromcombinedseweroverflowstoofrequentlyandinexcessivequantitiesintotheRiverThames.

3.1.2 Passedin1991,theUrbanWasteWaterTreatmentDirectivewastheprevailingregulatoryframeworkatthetimetheThamesTidewayStrategyStudyevaluatedLondon’soptionstoaddressstormwaterandsewageoverflow.TheDirectiveconcernsthecollection,treatmentanddischargeofurbanwastewaterandthetreatmentanddischargeofwastewaterfromcertainindustrialsectors.TransposedintoEnglishlawin1994,Annex1oftheDirectivehasguidedtherequirementsforcollectingsystems:

“Thedesign,constructionandmaintenanceofcollectingsystemsshallbeundertakeninaccordancewiththebesttechnicalknowledgenotentailingexcessivecosts,notablyregarding:volumeandcharacteristicsofurbanwastewater,preventionofleaks,andthelimitationofpollutionofreceivingwatersduetostormwateroverflows.”

TheDirectiveissilentasregardsthenumberofpermissibleoverflowsperyear.ThatisfortheMemberStatetoconsiderwhenassessingtheappropriatemeasurestolimitpollution.

3.1.3 TherewasageneralviewthatthethreekeyEUDirectivesinthisarea:theWaterFrameworkDirective,theFloodingDirectiveandtheUrbanWasteWaterTreatmentDirectiveareallcomplementaryandreinforcingbutthatthefundamentalonehastobetheWaterFrameworkDirectiveinthatitsetsoutthecriteriaforestablishinggoodecologicalstatusforEuropeanrivers.Itwasacknowledgedthattherehasalwaysbeenaproblemindeterminingwhatgoodecologicalstatusmeansforanopenurbanandtidalriver,andthatthisisstillbeingdebatedbutthattheWaterFrameworkDirectiveseekstoestablishthisand,assuch,shouldbetheprimarydriverofwatermanagementinrelationtooururbanrivers.TheUrbanWasteWaterTreatmentDirectiveandtheFloodingDirectiveshould“rideonthebackoftheFrameworkDirective”,accordingtoDefra.

3.1.4 Theinfractionproceedings,relatingtotheUrbanWasteWaterTreatmentDirective(UWWTD),areclearlydrivingDefra’sfocusonasingletunnelsolution.TheGovernmentisoftheopinionthattheEuropeanCommission’stimetableforcompliancewiththeDirectiveissuchthatSuDScanplayaveryminimalpartindelivery.AlthoughtheredoesnotappeartobeacleardeadlinesetbytheECforcompliancewiththeUWWTD,theCommissionwasunabletoclarifywhatscopetheremightbeforapartialSuDSsolutionbeingproposedoveralongerperiodoftime.TheGovernmentisreliantontheTTSSreportof2006andAppendixEinthe2010consultationdocumentsindeterminingthatgreensolutionswillbedifficulttoimplementinmeetingtherequirementsoftheUWWTD.TheCommissionfoundnoevidenceofanydialoguewiththeEuropeanCommissionontheacceptabilityofothersolutionsforthepresumedinfractionoftheUWWTD,noronthelongtermsustainabilityofsolutions,noronthewaystobestintegratetheplansformeetingUWWTD,theWaterFrameworkDirectiveandtheFloodDirective.

3.1.5 RajBhatiaprovidedwrittenevidencethat,aspartofthe‘DrainLondon’initiative,ThamesWaterhasproposedSuDSretrofitmeasuresinLondon,includingdetentionbasins,greenroofs,pocketstreetinfiltrationandpermeablepaving,manyofwhich,overthemediumtolong-term,


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bythefactthatdecisionsonsuchasignificantinvestmentastheconstructionoftheThamesTunnelwerebasedoncomputermodelingresultsthathadaweakscientificbaseandcouldnotbeverifiedduetothelackofknowledgeandmonitoringdata.Theefficacyofthemodelingcouldnot,however,beassessedindetailbytheCommissionasmodelingreportsandresultswerenotprovidedinevidence,despiterepeatedrequests.Duetothelackofscientificrigourintheanalyses,thesomewhatarbitrarycategorisationofsomeofthelowerlevelpollutingCSOswasbroughtintoquestion,asalessthanscientificmethodofselectingforconnection.

3.3.2 OnthebasisofthemonitoringofindividualCSOdischargestherewasanargumentpresentedbysomewitnessesthatthelessertomid-pollutingCSOscouldbetackledbySuDSand/orlocaltreatment.ItwasalsorevealedthatThamesWaterhasbeenconductingmoreaccuratemonitoring,astopollutingloads,attheninepumpedCSOs.Thisdatahasnotbeenreleasedbutitisbeingusedtovalidatethemodelingandthisprocessisstillongoing.TherewascriticismofthefactthatthislevelofmonitoringisnotbeingconductedacrossalltheCSOsthatmightbeconnectedtothetunnel.

3.3.3 TheEnvironmentAgency(EA)has20yearsofmonitoringdataondissolvedoxygenlevelsintheThames,whichwasnotprovidedinevidenceandwhich,itargued,isbetterwaterqualitydatathananywhereelseinthecountry.TheEA,initsevidence,pointedtoLondon’sclaysoilandthelackoflargeareasoflandasproblemsinintroducingSuDSasthesolutiontoreducestormwaterrunoffandCSOvolumesandfrequencies.Theseassumptionswerenevertested.OneofthewitnessesshowedampleevidenceoftheavailabilityoflandthroughoutLondon–exceptforthecitycentre–whileotherspointedatwaterstorageopportunitiesonroofs,inbasements,underroadsandelsewhere.AppendixEinthe2010consultationdocumentdemonstratedthatinmanypartsofLondon,therearemanyopportunitiestoretrofitSuDSandillustratedhowthismightbedone.

3.3.4 TheAgencyalsostatedthatthewesttoeastinterceptorsewersarerunningatclosetofullcapacityatcertaintimes,evenindryweatherflow.Thisis,however,agoodreasontoimplementSuDSinordertoretainstormwaterlocally,ratherthandrainitwithoutdelayintothesewersystemandthiswillalsohelpmanagefloodrisks.DealingwithovercapacitysewersintimesofdryweatheralsorequirescontrolofinputsnearertosourceandtheCommissionweresurprisedthatnoconsiderationhadbeengiventoprovidingnewdispersedSTWstoreducethefoulflowsgoingintothemaindrainagenetwork,incommonwiththeapproachbeingtakeninmanyotherpartsoftheworld.

3.3.5 Enlargingthecapacityoftheinterceptors,e.g.bybuildingthetunnel,wouldrequireafurtherextensionofthehydrauliccapacityoftheconnectedSTWs,astheywillbedealingwithalargervolumeofwateratahigherflowrate.Itisunclearhowthisextensionisincludedinplanningandbudgeting.

3.4 Estimatingcosts/benefitsandtheimpactonThamesWaterbillpayers

3.4.1 TheapproximateestimateofthepreferredOption1cinDecember2006,withoutadetailedschemedesign,was£2.16billion.ThecurrentpreferreddesignisashortertunnelthanOption1cbutitscostisnowprojectedtobe£3.6billion,althoughthisisafigurethatwasusedbyThamesWaterin2008tobenchmarkandisexpectedtorise.ThamesWatercustomerswouldbepayingforthescheme.

3.4.2 Initsevidence,Ofwatexpresseditsdesiretoachievethebestvalueformoneysecuredforcustomers,giventhesolutionasitstands.Ofwatrecognisestheenormityoftheproject,eveninrelationtoThamesWater,whichisthebiggestwatercompanyintheUK.Theregulatorybodyalsorecognisesthattheimpactoncustomerbillswillberelativelylarge–a£60to£65increaseinannualbills,whichcurrentlyaverage£319.

definitelyinrelationtothelongtermsolutionsbeingsought.

3.2.6 TheCommissionheardevidencethatSuDScanmitigatemostofthepollutantspickedupbystormwater,whereasthetunnel,whileaddressingtheacutepollutionproblems,willnothelptoaddressthecumulativeandlongtermpollutingproblemsthatintroducingstormwaterintotheseweragesystemcancause.NorwillithelpwithaddressingfloodingriskintheCity.

3.2.7 OneexpertnotedthatUKpolicyonsourcecontrolforthesemicropollutantsdoesappeartoespousetheintroductionofsustainabledrainagesystemsbutthattheimplementationofsuchsolutionsispiecemeal,i.e.thereisaprobleminextrapolatingthestrategicobjectivesintooutcomesimplementedontheground.

3.2.8 SomeexpertwitnessesquestionedtheextenttowhichtheaestheticcriteriawereofrelevancetothetermsoftheUWWTD,whichreferstoenvironmentaldamage.Thescientificvalueofmonitoringtheaestheticcriteriawasalsoquestioned.Itwaspointedout,forexample,thataestheticmonitoringofpollution(muchofwhichhasbeenhearsay)cannotidentifywhichCSOisresponsibleforthedischargeastheThamesisaveryturbidflowofwaterandthetidewillcarrypollutantsanddetritusforsomemilesupanddownstream.

3.2.9 Referencewasalsomadetothe‘BromleyCase’,inwhichtheAdvocateGeneral’sopiniononwhatthe‘besttechnicalknowledgenotentailingexcessivecost’actuallymeanswasgiven.Insimpleterms,hislegalopinionwasthatthecostsoffixingtheproblemiscomparedtotheharmthatwillcontinueifitisnotfixed.

3.2.10 LambethCouncil’sevidencerecognisesthatduetobothpopulationgrowthandrequireddevelopmenttherewillbeincreasedpressureonexistinginfrastructureandthattherewillultimatelybetheneedforamajorcivilengineeringprojecttoaccommodatesuchgrowthinLondon.However,theCouncilsaystheThamesTidewayTunnelshouldconsidertakingamoreholisticapproachandbeaccompaniedbycomplimentary‘softer’measurestoaddressflooding.

3.2.11 ItwaswidelyagreedthatpollutionintheRiverThameshasvastlyimprovedoverthepastthirtyyears–thePortofLondonAuthority(quotingtheEnvironmentAgency)boastedthatitisthecleanestmetropolitanestuaryinEurope-butthatthecurrentlevelsofsewagegoingintotheriverareunacceptable.

3.2.12 TheCommissionconcludesthatindeedthereisanurgentneedtoaddresstheproblemoftheCSOdischarges.Alongtermsustainablesolutionisrequired,addressingtheCSOproblemfromthewidercontextofproblems,challengesandopportunitiesinrelationtoLondon’surbanwatermanagementandtakingintoaccounttheneedforadaptationtoexternaldevelopmentssuchasclimatechange,shortagesofnaturalresources(e.g.energynutrients,water),developmentsintechnologyanddemography,inassetvalues,fundingsystemsandingovernancepractices.Atthesametime,seekingtomaximisetheopportunitiestoprovidenewgreeninfrastructureandbetterplacestoliveinlinewiththeMayor’saspirationsforLondontobethegreenestCityinEurope.StormwaterisakeyresourcethatcanbeutilisedtokeepLondongreen;withoutthis,greenareaswillneedtobewateredwithexpensiveandwastefultapwater.

3.3 Questioningdecisionsforconnectionsandverifyingmodelswithdatacollection

3.3.1 Inherevidence,theChairmanoftheStoptheShaftgroup,SianBaxter,referredtoEnvironmentAgencymonitoringthatsuggeststhat98.7%ofdischargescomefrom18CSOs,andsoquestionedwhetheranyotheroutflowsneedtobeaddressed.ThesamemonitoringdatashowsthatfiveCSOscontributesome70%ofthedischarge.ThevalueformoneyaspectofconnectingmarginallypollutingCSOstotheTunnelwasraisedaswasthequalityandaccuracyoftheEAandTWmonitoringofindividualCSOdischarges.TheCommissionwassurprised


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theGovernment’sdecisionin2007,however,thatthetunnelwastheonlyadequatesolution.InevidencetotheCommission,however,Ofwatnotedthattherewasafeelingwithintheorganisationthat,withachangeofgovernmenttheremightbeanopportunitytolookatitagain.

3.5.4 TheformerChairmanoftheTTSSGroup,ProfessorChrisBinnie,gaveevidencethatthemaintechnicalreviewofSuDS,thatinformedthestrategicstudy,wastheBinnie,BlackandVeachreport,conductedin2002.Inhisevidence,ProfessorBinnieacceptedthatthe£12,000investedinthisstudywasaminisculeproportionofthe£5millioninvestedinthewholestrategicstudy.

3.5.5 TheGreaterLondonAuthority(GLA),whileexpressingsupportforthetunnel,acceptstheneedtoextenditsexistinggreeninfrastructureprojectsandtoimplementrelatedplanningpoliciescontainedwithintheLondonPlan.TheGLArecognisestheneedforamixedeconomysolutionofbothgreyandgreeninfrastructureandisopentoproposalsforspeedinguptheintroductionofSuDSsolutions.

3.5.6 WhiletheGovernment’schangestothepermitteddevelopmentrights,in2010,wererecognisedasastepforwardsonimplementinggreeninfrastructure,therelaxationofsomeoftheothercontrolsoverrainwaterdischarge,withlocalauthoritiesnolongerhavingthepowertoenforceSuDSforrearextensionsorrearpatios,forexample,wasseenbytheGLAasastepbackwards.

3.5.7 ThamesWaterarealsodevelopingstrategicsewerfloodalleviationschemes,suchasCountersCreekinHammersmithandFulham,toaddresspeakdemandandstopsewerfloodinginhomes.TheThamesTunnelteamisalsoresponsiblefortheworkontheCountersCreekstrategicsewerbuttherearetwoseparateaimsdrivingthetwoschemes:oneisstoppingthedischargestotheriver,theotheroneisstoppingfloodinginhomes.AcrossLondonthereareactivitiesdeliveringfloodriskmanagementschemes,basedonsurfacewatermanagementplans,byDrainLondonandThamesWater’sregulatorycomplianceunderDG5.Thereisnointerconnectednessbetweentheseandthetunnel.Customersandpropertytaxpayerswillhavetopayadditionalcostsoverandabovethoserequiredforthetunnelofseveralmillionpoundsforfloodriskreduction.Anintegratedapproachtostormandwatermanagement,astakenelsewhereintheworld,woulddelivergreaterbenefitsandatlesscost.

3.5.8 AtBecktonsewagetreatmentworks,ThamesWaterisincreasingthetreatmentcapacityfrom17cubicmetresasecondupto27,another10cubicmetresasecondoftreatmentcapacity.Thiswillenabletreatmentofmoreflowinwetweather.Otherimprovementstotreatmentworksarealsoongoing.Inevidence,thecompanystatedthattheynowhavestringentsuspendedsolidslimits:theammoniastandardisreducedasistheBiochemicalOxygenDemand(BOD).Allofthesecondarytreatmentparametersarebeingimproved.ThamesWaterdidnotruleoutthepossibleconstructionofanewsewageworks.

3.5.9 ThamesWaterviewsSuDSastherightthingtodofornewdevelopment,andameansoffuture-proofingwhateversolutionischosentoreduceCSOdischarge.Thecompanydoesnotbelieve,however,thatretro-fittingSuDSwouldreducethenumberofCSOdischargestoapointthatcomplieswiththecurrentlegislation.Theyarealsoconcernedthattheircustomersdonotbecomeadefaultfundingmechanismforschemesthatmightbemoreappropriatelyfundedbylocalcounciltaxpayers.AsfarastheCommissionwasabletoestablishneitherwasevertestedandverifiedbyresearchandanalysis.NorweretheseissueseverthesubjectofadebateonthewatermanagementstrategywiththerelevantpartiessuchasThamesWater,theGLA,theEnvironmentAgencyandtheLondonBoroughs.

3.4.3 Ofwatexpressedconcernsastotheincreasedcostassociatedwiththetunnel,pointingoutthatthe£2.23billionestimatein2006wasforthewholescheme:theThamesTunnel,theLeeTunnelandtheBecktonsewagetreatmentworksupgrade,meaningthatthecurrentestimateforthoseworksisnow£4.5billion-broadlydoublethe2006estimate.Inevidence,Ofwatnotedthatthecostbenefitanalysiswasmarginalin2006socanonlyhavegotworse.

3.4.4 TheConsumerCouncilforWater(CCW),initsoralevidencetotheCommission,calledforanew,environmentalauditoftheriver,followedbyacompletelyfreshcost-benefitanalysisofthewholetunnelproposal.TheCCWwasclearthatanysuchanalysisshouldtakeaccountofthefactthattheThameswillneverbebathingwaterandthattheriverisalwaysgoingtohavehighturbidityduetotidalaction.Thisshouldalsoestablishwhattherelativesourcesofthepollutantsenteringtheriverare:CSOs;diffuseinputs;fromupstream;STW.

3.4.5 CCWalsonotedthatanestimatedcostof£3.6billionforthetunnelworksoutatsomethinglike£120millionperkilometre,includingallthesuperstructureandconnections,soeverykilometrethatisdugwestofthecoreCentralLondonarea,isgoingtoincreasethecostatsomethinglikethatlevel.TheConsumerCouncil’sviewisthatbuildingasmallself-containedlocalsewagetreatmentworksinWestLondoncouldbeanoptionthatsignificantlyreducesthelengthandcostofthetunnel.The£18millionsewagetreatmentworksatReading,wascitedasanexampleofthepotentialcostsavings.

3.4.6 CouncillorRaviGovindia,LeaderofWandsworthCouncil,believesitisintheinterestofThamesWater’scustomersthataceilingisplacedonthemaximumcostssotheycanbeclearontheeffectitwillhaveontheirfuturewaterseweragecharges.

3.4.7 TheCommissionnotedthatmaximisingbenefitsforsocietywasneverthemainobjectiveoftheproject.Alternativeswereneverstudiedfromtheperspectiveofsynergiesorcollateralbenefits–actualorpotential–butratherasamono-functionalsolutiontoasingleproblem.

3.5 Understandingthebenefitsandimplementationhurdlesofgreeninfrastructurealternatives

3.5.1 TheMilwaukeeMetropolitanSewerageDistrict’sExecutiveDirector,KevinShafer,recommendsthattheThamesTunnelCommission,iffinanciallyfeasible,strivetomoveforwardwithmultipleapproachessimultaneously.IntheCity’spracticalexperience,multipleapproachesaremorelikelytoprovidesynergisticbenefitsthansinglesolutions.Simplyput,greeninfrastructuresupplementsgreyinfrastructureandhelpsitworkmoreefficiently.Mr.Shaferwrites,“Iknowthisthroughbothcomputermodelingandpracticalexperience.”

3.5.2 WaterCommissioner,HowardNeukrug,ofthePhiladelphiaWaterDepartmentbelievesthatexpansionsoftraditionalsewageoverflowcontrolsystemsisnotthesustainableapproachtodevelopingwaterqualitysolutionsforthefuture.Yesterday’ssewersystemswerenotdesignedtohandletoday’schallengeandtheeverexpandingregulatorysystem,nor,moreimportantly,aretheyequippedtomimicthenaturalstormwatermanagementprinciplesessentialfortrueecosystemrestoration.Agreenapproachtostormwatercontrolasanalternativetotraditionalapproachesbringswithitsignificantandmeasureableimprovementsintheurbanenvironment,includingbiodiversity,reductionsingreenhousegasemissions,reductionsinheatstress-relatedillnessandmortality,reductionsinelectricalandfuelusage,improvementsinaquaticandterrestrialecosystems,reductionsincrimeandassociatedwaterqualityenhancements.

3.5.3 DefraacceptstheneedforsustainabledrainagesystemsbutdoesnotacceptthatthesecanalleviatetheneedfortheThamesTunnelsolution,ascurrentlyproposed.Ofwathasconstantlyquestionedthevalueformoneyofthetunnelproposal,asisitsrole,andcommissionedtheJacobsBabtiestudyinordertoexploremorecosteffectiveoptions.Theregulatoraccepted


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thiswouldbeaconsiderablestartandwouldnotneedalotofretrofitting.Itwouldrequirethenecessarygovernanceandfundingstreamsthoughtomakeitwork.

3.5.17 CllrStephenGreenhalghnotedthedifferentgovernancestructuresofBritishandUScitiesasoneofthereasonswhytheUSissofaraheadinintroducingSuDS.Chicagohasaclearaccountabletechnicalofficerresponsibleforwaterqualityandenvironmentalissuesatastrategiclevel.TheCommissionerforWaterQualityandEnvironmentalIssuesisresponsibleforintroducingSuDSprogrammesacrossthecity.

3.5.10 Ofwatreferredtotheproblemsofsitingnewsewagetreatmentworks,duetoplanningrequirementsandtheobjectionsoflocalresidents.AnewworksinBrightontooksome10yearstobegrantedplanningpermission.OfwatwouldencouragethewatercompaniestofundSuDS,whereitiscostbeneficial.

3.5.11 TheCommissionwastoldthatthatsuchsubsidyschemesfordisconnectingroofsandpavedsurfacesfromcombinedsewersystemsareoperationalandsuccessfulinmanycitiesabroad.

3.5.12 ProfessorBryanEllisnotedsomeoftheproblemsinmaintainingSuDSinUKcities,wheresomanydifferentauthoritiesandcompaniesareresponsibleformaintaininginfrastructure,e.g.porouspavementsmayberegularlydugupbydifferentutilitiesandtelecommunicationscompanies.HepointedtopracticeinJapanasameansofovercomingtheseproblems,wheretheyhaveco-ordinatedapproachesforfiveyearsintheintroductionofinfrastructure.

3.5.13 ProfessorElliswascriticalofthelackofaproperplanningreviewfortheintroductionofSuDS.ItishisbeliefthatthisshouldhavedevelopedfromtheThamesTidewayStrategicStudybutdidnot,duetothefactthattheremitoftheoriginalcontractorsemployedtodothemodelingworkwasconcernedwithlookingatspillage,frequenciesandratesandvolumesrelatedtotheCSOs.Theywerenotrequired,specifically,toaddresstheissueofpluvialflooding(byheavyrainfall)incontrasttoriverflooding.SuDSisseenasdesirablebyallbutitsimplementationappearstohavebeenrelegatedtosomefuturetimeduetoperceivedproblemsinintroducingandmaintainingsuchsystems.ProfessorElliswouldliketoseebetterliaisonbetweentheLondonBoroughsandThamesWater,toimproveco-operationandcollaborationintheintroductionofSuDS.Hereferredtoonesuccessfulcollaborativestudy,beingfundedbyThamesWater,forwhicharaingardenhasbeenconstructedinIslington.ItisthefirsttimethataraingardenhasbeenmonitoredinLondontoidentifyhowmuchwateritistakingoutoftheseweragesystem.Itisaverysmallraingarden,a30metresquareofroofsurface,butearlymonitoringresultshadshownthatatthatdateithadtakenoutalltherainfall.

3.5.14 ProfessorEllisarguesthatthecurrentapproachoftheEnvironmentAgencyneedsmodification,andhebelievesthattheEnvironmentAgencyhaverecognisedthis.IndiscussionswithBirminghamCityCounciltheAgencyhasrecognisedthatitssurfacewatermapsareonlyjustthefirstbroadscreening,andthattheCouncilshouldnotrelyupontheseasfirmindicationsoffloodingdistributionsanddepthswithintheirarea.Identifyingtheproblemisthefirstpartofthemodeling,thesecondpartisfindingthesolution.Amodelingapproachisavailable,whichlooksatwhattheappropriatetypesofSuDSarethatcouldbeusedtoaddresstheproblem,andwheretheycouldbelocated.

3.5.15 Themodelisaprocedurewhichallowsthescanningofasiteordevelopmentorsubcatchment,toidentify,forexample,whereflatroofsare,wherecarparksare,etc.Itcaneliminateroofswithmorethan3degreesasbeingunsuitableforgreentechnologiesandthenincombinationwithgroundwatermapsitcanidentifywhereattenuationstoragecanbeprovided.ThemodelidentifieswhatparticularkindsofSuDSareappropriateandwheretheycanbelocatedinthecatchment.ThemodelisrerunwiththeSuDSinsertedtoseewhatthebenefitsareintermsofflowreduction.

3.5.16 ProfessorEllisdidnotbelievethatthepublicwouldbeunacceptingofSuDSschemes,e.g.thefloodingofparks,assomehavesuggested.HepointedoutthatthefloodmeadowsinLondonarealwaysoperationalandthatpeopleacceptedtheminthepast.ThemainproblemthatheseeswithSuDSisensuringthatthesearemaintainedovertimeintheprivatesector.Overa20or30yeartimescale,itwasProfessorEllis’sbeliefthatsufficientalternativedrainageinfrastructurecouldbeputintoplacetocontrolasmuchas90%ofevents.Hesuggestedthatlegislationshouldrequirethatatleastthefirst10to15millimetresofrainwaterrun-offshouldbecontainedorretainedonsiteorwithinadevelopmentandnotreleased.Itwashisviewthat


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treatment,storageandtransmissionfacilities.Greeninfrastructurepractices,suchasrainwaterharvestingtechniqueshelpcaptureandconservewater.Harvestedstormwatercanbeusedforlowenddomesticpurposessuchasirrigatinggardens,toiletflushingandlaundrywashing.Downspoutdisconnections,raingardens,porouspavements,curblessparkinglots,andnarrowerroadscanalsohelpreplenishandsustaingroundwater.

Heatstressreduction

4.1.6 Evaporationhelpsalleviateheatstress.Retainedstormwatercanbeusedformaximisingevaporationduringhotdryspells.Watercanbeusedfordirectevaporativecoolingfromwettedpavementsandroofsorforindirectevaporativecoolingbyplantevaporation.Reductionofheatstressreducesenergydemandforairconditioning.

Ancillarybenefits

4.1.7 Greeninfrastructureisalsoattractivebecauseitcanbeusedtoachievemultipleecologicalenvironmental,socialandeconomicgoals,measuredbysomeasshorterhospitalstays,reducedinstancesofchildhoodobesity,reducedcrime(perceivedandactual),increasedcommunityinteraction,airandnoisequalitybenefits,andthelistcontinues.Whereasfundsspentonconventionalstormwatermanagementcanonlybeusedforwaterinfrastructure.TheThamesTunnelisamono-functionaldeviceintermsthatitcanonlybeusedforthestorageandconveyanceofwastewater.Whateverthemotivationisforevaluatinggreeninfrastructureanditsvariousoptions,bestmanagementpracticesacrosstheliteraturefindthatlandusestendtodictatethebestgreeninfrastructuremeasurefit,aswellascosts,storagecapacities,andtreatmentabilities.Mostbenefitstranslateintoqualityoflifeandeconomicvaluesuchashigherpropertyvalues.

4.2 EvidencefromtheUS

4.2.1 MitigatingCSOsiscostly.A2000‘CleanWatershedsNeedsSurvey’estimatedthat$56billion(2005dollars)incapitalinvestmentwasneededforU.S.CSOcontrol.SeparatingcombinedsewerlinesandbuildingdeepstoragereservoirsortunnelsarethetwomostcommongreyinfrastructuremethodsofCSOcontrol.Thecostsforseparatingcombinedsewers,disconnectingstormwaterinletsfromthecombinedsewersystems,anddirectingthemtoanewlyinstalledseparatestormsewersystemrangefrom$2.6millionto$3.2millionforeachmileofcombinedsewertobeseparated.Deepstoragesystems,builttoholdtheexcesssurgeofcombinedsewerwastewaterduringwetweatherevents,takeyearstobuildandarecostly.

4.2.2 Yet,morerecentdataisbeinggatheredonhowgreeninfrastructurestrategiesreducestormwatercosts—competitively.TheU.S.EnvironmentalProtectionAgencysummarised17casestudiesofdevelopmentsapplyinggreeninfrastructuretechniquesinDecember2007,concludingthat“inmostcases,[greeninfrastructure]practiceswereshowntobebothfiscallyandenvironmentallybeneficial”withtotalcapitalcostssavingsrangingfrom15%to80%,withafewexceptions.

4.2.3 InNewYorkCity,wheretheDepartmentofEnvironmentalProtection(DEP)foundthatthebiggestremainingchallengetowaterqualitystandardsareCSOs,thecitydecidedinitsSustainableStormwaterManagementPlantopursueahybridgrey-greenapproach.Since2005,thecityhasspentmorethan$1.5billiononCSOreductionincludinginfrastructureimprovementsandCSOstoragefacilityupgrades.ButaccordingtotheSeptember2010NYCGreenInfrastructurePlanreport,thesetypesofCSOreductionprojectsareveryexpensiveanddonotprovidethesustainabilitybenefitsthatNewYorkershavecometoexpectfrommultibilliondollarpublicfundinvestments.NewYork’sDEPmodelingeffortsdemonstratedthattheuseofgreeninfrastructureincombinationwithotherstrategieswouldnotonlybemoreeffectiveatcontrollingCSOs,ascomparedtogreystrategiesalone,butwouldalso

4. INVESTIGATIONOFALTERNATIVESOLUTIONS4.1 Greeninfrastructureoptions

4.1.1 Greeninfrastructure(GI),alsoreferredtoaslowimpactdevelopment(LID)orsustainabledrainagesystems(SuDS),arepracticesthatcanbeusedtoaddressstormwaterproblemsatsourcebyrestoringsomeofthenaturalhydrologicfunctionsofurbanisedareas.Itcanalsoencompasslimiteddevelopmentinsensitiveheadwaterregionsandgroundwaterrechargeareasbut,morerecently,theattentionhasfocusedatthecity,neighbourhoodandsite-levelscalewiththecaptureandretentionofrainfall,infiltrationofrunoff,andthetrappingandabsorptionofpollutionthroughdecentralised,engineeredstormwatercontrols.EngineeredsystemsmostcommonlybeingusedinU.S.andAustralianurbanareasincludegreenroofs,raingardens,rainbarrelsandcisterns,vegetatedswales,pocketwetlands,andpermeablepavements.Greeninfrastructurealsoencouragesnarrowerstreetwidths,greeningtheurbanenvironment,andparkinglotsborderedbydrainageswales.Withupto70%ofthetotalimperviouscoverinU.S.urbanareasattributabletotransportation-relatedsurfaces,andamajorityofthatcoverdirectlyconnectedtostormdrainsystemsandalongwaterways,suchsurfacescanoftenproducethefirstrunoffduringstormevents.

4.1.2 Incontrasttoconventionalcentralisedcontrols,thebenefitsofgreeninfrastructurearethatitisdecentralised,isadaptableandoffersflexibilityandsite-specificsolutionsthatcanbetailoredtobothnewlydevelopedlandorretrofittedintoexistingareas.Facilitiescanbeinstalledonandinprivateaswellason/inpublicland.Evenin100%pavedareas,greeninfrastructurecanbeappliedtoprovidelocalwatersupplies,reduceandretainstormwaterrunoff,e.gbyacombinationofgreenroofs,raintanksandundergroundinfiltrationfacilities.GIcanbeusedonindividualsitesorindividualneighbourhoodstoaddresslocalisedstormwaterorCSOproblems,orincorporatedintoamorewidespreadmunicipalstormwatermanagementprogramme.Othermajorbenefitsincludestormwatervolumecontrol,pollutantremoval,waterconservationandahostofotherancillarybenefits,discussedinmoredetailbelow.

Stormwatervolumecontrol

4.1.3 Traditionalstormwatermanagementfocusesonflowratesfromlargerstorms.Thisapproachoverlookstheimportanceofvolumecontrolfromstorms.Itisincreasinglyclearfrommountingevidence,however,thatreducingtheamountofurbanrunoffisthemosteffectivestormwaterpollutioncontrol.Reducingrunoffvolumesdecreasestheoverallvolumeenteringcombinedsewersystems,reducingthenumberandsizeofoverflows.Effectivepracticesforprovidingvolumereductionbenefitsincludegreenroofs,permeablepavements,infiltrationswalesandcrates,bioretention,trees,andwaterharvestingpractices.

Pollutantremoval

4.1.4 Notonlydoesgreeninfrastructuredecreasepollutantloadsbyreducingrunoffvolumes,thereisagrowingbodyofworkindicatingthatgreeninfrastructurepracticesareeffectiveatremovingpollutantsfromstormwaterdirectly.Usingnaturalprocesses,greeninfrastructurefilterspollutantsorbiologicallyorchemicallydegradesthem,whichisespeciallyadvantageoustoseparatesewersystemsthatdonotprovideadditionaltreatmentbeforedischargingstormwater.Effectivepracticesincludeopenareasandbufferzonesaroundurbanstreamsandriverstoprovidetreatmentandmanagementofoverlandflowbeforeitreachesthewaterway.

Waterconservation

4.1.5 Communitiesacrosstheglobemustfindwaystorespondtowatersupplyshortfalls.Waterconservationcanhelpalleviatethesethreatsbyallowingcommunitiestomaximisetheirexistingandplannedwatersupplysourcesandpreventtheneedforcostlyexpansionofwater


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4.3.2 AlternativesforthemanagementofstormwaternearertosourcehavebeenconsideredduringtheformulationoftheTTTscheme.ThefirstofthesewasastudybyBlackandVeatchforthe2005schemereview.ThisreportedthatthereweresomegroundsforconsideringtheuseofSuDSincertainareas.

4.3.3 ThemostcomprehensiveassessmentofSuDSviabilitywascarriedoutin2009.Thiswaspresentedintheconsultationof2010asAppendixE3.Thespecificationforthisstudy,asforthoseearlier,wastodeterminethecostandeffectivenessoftheuseofSuDSinreducingoreliminatingoverflowsintotheRiver.Nowiderconsiderations,suchasfloodriskreductionsorqualityofurbanlifeweretobeconsideredinthestudy.

4.3.4 DuetothetimeandresourcesavailableforthestudyonlyalimitedrangeofSuDScouldbeconsideredforretrofittingandonly3ofthesewercatchmentsintheTTTareacouldbestudied.Thethreeexampleareaswerelocatedinthewestofthecatchment,southoftheRiverThames;thesubcatchmentscontributingtotheWestPutney,PutneyBridgeandFrogmore(BuckholdRoad)CSOs.Frogmore(BuckholdRoad)comprises454hamixeduseurbanarea;WestPutneyandPutneyBridgecatchmentsare425haand142harespectively.Thisstudyshoweditwasrelativelystraightforwardtodisconnectsignificantamounts,easilysome40%ofthepavedareasinthecatchmentsexamined.

4.3.5 ComputermodellingbyCH2MHillshowedparticularlypromisingresultsforthepotentialdisconnectioninthePutneyBridgeandFrogmoresubcatchments.Forthetypicalyear,the50%removaloptionresultsinreducednumbersofCSOevents,maximumflowratesandtotaloverflowvolume.ForFrogmore(whichisthebestcase),forexample,thenumberofeventsisreducedfrom29to10(-66%),andthetotaloverflowvolumefrom94,500m3downto21,400m3(-77%).Thenumberofeventsproducingover1000m3isalsosignificantlyreducedatallthreeCSOs.Theimpactofremovingthefirst5mmofrainfall(viastorageinblue/greenroofsetc.)haslittleimpactonthelargestormsconsideredhere.However,agreaterdepthof50mmwouldhavebeensufficienttocontaineachoftherainfalleventsinthetypicalyear.

4.3.6 Thestudyshowedthatdisconnecting50%oftheimpermeableareafromtheentirecatchmentareaswouldreducethetotaloverflowvolumeby54%;reducingthenumberofCSOspillsinatypicalyearto3(areductionof90%)foroneofthemajorCSOcatchments.Thiswouldrequirethedisconnectionofsome10,327haofconnectedhardsurfacessuchasroofs,drives,carparks,roadsandpavements.Thisisnotaninconsiderableamount(equivalenttoapproximately15,000footballpitches)butcomparedtothetotalityofunpavedareainthecatchmentitmustbefeasible.

4.3.7 AmoreconstanthydraulicloadingandamoreconstantqualityoftheinfluentofSTWimprovethetreatmentefficiency;longperiodsofheavyhydraulicloadingrequireextracapacityofthesludgesettlerstoavoidsludgeoverflows.SuchprolongedperiodsofheavyhydraulicloadingwouldresultfromtheemptyingoftheTunnelafteritwasfilledbyastorm.

4.3.8 Ultimatelythesescenarioswerefurtherrefinedtoreflectopportunitieslikelytobecost-effectiveandacceptabletorelevantstakeholders,althoughnomodelingoftheseoptionswasundertaken.Inthiscontexttheexistenceoflargeareasoflowtomedium-risemunicipalhousingblocks,oftenflat-roofedandsetinextensivegrassedgrounds,wasseentoprovidean

providetheadditionalbenefitsofcoolingthecity,reducingenergycosts,andincreasingpropertyvalues—andthestudyfoundthatgreeninfrastructurecouldbemorecosteffectivethancertainlargeinfrastructureprojects,suchasCSOdeepstoragetunnels(Gunderson/DEP).Thecostsforeachstrategywerealsocalculatedonaunitcostbasis.BasedonthecostpercubicmetreofCSOreductionforeachrespectivealternative,thegreystrategyisestimatedtobethemoreexpensiveoption($0.62pergallonforthegreystrategyversus$0.45pergallonforthegreenoption).Inparticular,thecostsofbuildinggreeninnewdevelopmentsislessthanacentralisedCSOapproachorconventionalstormwatermanagementprogrammesandmayprovideanopportunitytofurtherdecreasetheeconomiccosts.

4.2.4 StudiesinMarylandandIllinoisshowthatnewresidentialdevelopmentsusinggreeninfrastructurestormwatercontrolssaved$3,500to$4,500perquarter-tohalf-acrelot.Costsavingsforthesedevelopmentsincludeavertedcostsforlessconventionalstormwaterinfrastructureandpaving,andlowersitepreparationcosts.Addingtothecostsavings,developmentsusinggreeninfrastructurenormallyyieldmorelotsforsaleandhighersalespricesbecauseofthepremiumbuyersplaceonvegetationandconservationdevelopment.

4.2.5 Inurbanareas,greeninfrastructurewillbemostcosteffectivewhenitisincorporatedaspartofanoverallredevelopmenteffortorwhenlargeimprovementstoinfrastructurearerequired.Intheseinstances,thecostsofgreeninfrastructureareminimisedrelativetothescopeandcostsoftheoverallproject,asinthecaseoftheearlierNewYorkexample.

4.2.6 Althoughgreeninfrastructurehasbeenshowntoreducestormwaterrunoffandcombinedseweroverflowsandimprovewaterquality,itsvalueasanalternativeisonlyasgoodasitcanbeimplemented—andmeasured.U.S.citieshaveincorporatedgreeninfrastructureintostormwatermanagementprogramsbecauseofdirecteffortstoencouragealternativestormwaterapproaches.Buttheapproachisbenefittingfrompolicyprescriptionsbeingputintoplaceoverthelast5-10years,rangingfromincorporatinggreeninfrastructureintolong-termcontrolstrategiesforCSOs(somecitiesareevencreatingstormwaterutilitiessimilarinfunctiontowaterandwastewaterutilitiestoallowfortheassessmentandcollectionofauserfeededicatedtostormwatermanagementprograms)todedicatedfundingforstormwatermanagementthatrewardsgreendesigntoprovidingincentivesforresidentialandcommercialuseofgreeninfrastructure.Asjustoneexample,beginningin2006,Portland,Oregonprovideduptoa25%discountinitsstormwaterutilityfeeforpropertieswithon-sitestormwatermanagement.

4.3 DeliveringmultiplebenefitsfromusingSustainableDrainageSystems(SuDS)andWaterSensitiveUrbanDesign(WSUD)

4.3.1 Valuecreationisthekeytomodernurbanplanningandwithinthis,watermanagement,whichshouldbeintegratedintothewiderangeofsocietalfunctionsandisnolongertheprovinceofthewatersystemspecialistalone.Managingwaterintoday’smoderncityrequiresaco-creativeapproachbetweenpolicymakers,professionalsandcitizensandtheuseofsourcecontrolmeasures(knownasSuDSintheUK)isnowstandardpracticethroughoutmostoftheworld.Theout-of-sight,out-of-mindapproachespeciallytodrainageandwastewater,wheredrainsandsewersconveythewateraway,identifiedinthe2004NAOreport1isnolongertenablegivenrecentknowledgeadvancesthatseeallformsofwaterintheurbanenvironmentaspotentialresourcesandameansofprovidingopportunitiestoenhanceurbanlivingatlowcost.Forexample,the‘GreeningforGrowth’projectinVictoriainLondon2seekstoembedthenaturalenvironmentinthecreationofasustainableandclimate-resilient126habusinessarea.Withoutsurfacewatermanagement,providingirrigationforthegreenareasandalsocontrollingfloodingofVictoriastationusing25haofgreenroofsthatdealwith80,000m3ofrainwaterannually,theschemewouldnotbeabletobedelivered.

1NAO (2004) Out of sight - not out of mind. HC 161 Session 2003-2004: 16 January.

2Landscape Institute (2011) Local Green Infrastructure.

3Ashley, R, Stovin, V, Moore, S, Hurley, L, Lewis, L and Saul, A, 2009, London Tideway Tunnels Programme Thames Tunnel Project Needs Report - Potential source control and SUDS applications: Land use and retrofit options 29th July 2009 [http://www.thamestunnelconsultation.co.uk/consultation-documents.aspx]


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sizeorcapacity,creatingadditionalstoragethisway.Itiscontendedthatfurtherpopulationgrowthwillexacerbatethisproblem.Yet,thereseemstobenoattempttoconsidertheuseofdispersedwastewatertreatmentplantsorretrofitinperipheralcatchmentareas.Globallytheuseofdecentralisedwastewaterfacilitieshasgrown,acknowledgingtheirinherentflexibilityandhenceresiliencecomparedwithlargeend-of-pipeplants.Inaddition,decentralisedfacilitiesalsoreducepumpingcosts.Localresource(nutrient)andenergyrecovery(closingtheurbanwater,nutrientsandenergycycletogether)fromthewastewaterattheseplantsisseentobeafutureopportunityandonethatavoidstheneedforlongdistanceconveyanceinexpensiveupsizedsewers.

4.3.15 TWshouldbesettingmoreambitiousgoalsandobjectivesforurbandrainage,watermanagementandwatersupplyfortheshort,mediumandlongtermthatfocusontheopportunitiesratherthanthethreats.TheCommissionproposesthatanewandmorewiderangingcost-benefitstudybeundertakentoinvestigatethepotentialmulti-functionalvalueandfeasibilityofretrofittingmainlyGIsourcecontrolmeasuresasanalternativetoconnectingcertainoftheCSOstothetunnelandalsotoconsidertheoptionsfordecentralisedwastewatertreatmenttotackletheoverloadedsewers.TheaddedbenefitsshouldincludemakingLondonmoreclimateresilient,integrationwithfloodriskmanagementmeasures,theMayor’sdriveforadditionalgreeninfrastructurevialanduseplanningand,notleast,providinggreenjobsanddevolvedresponsibilitiestocommunitiesunderthe‘BigSociety’initiative.

4.3.16 ThisstudywouldrequireaccesstoThamesWater’scomputationalmodelsofthesewernetwork,especiallytoverifytheeffectsofanyproposedsourcecontrolanddecentralisationonthehighlycomplexandinterconnectedsewernetworkinLondonaswellasontheemissionsoftheCSOsandtheSTWs.Thestudywouldneedtobeconductedbyexperienced,independentandcompetentconsultantsandwouldneedtomeettheverytighttimetableforrespondingtotheimpending2ndstageTidewayTunnelconsultation.ItwasadisappointmenttotheCommissionthatdespitenumerousrequests,accesswasnotprovidedtothereportsaboutthevalidationandresultsfromthecomputermodelsusedinthemostrecentanalyses.

excellentandcost-effectiveopportunityforretrofittingSuDS.WhilstnotprovidingacompletesolutiontoalloftheCSOspills,SuDSwereshowntobeeffectiveenoughatmakingsignificantreductionssuchthattheresidualspillsatcertainCSOscouldbemanagedlocallyand/orareducedlengthoftunnelcouldbeemployedmuchasisbeingdoneinPhiladelphia,Bostonandanumberofothercities.Londonisunusualinthatitseemstogoforamono-solution–theThamesTidewayTunnelbutthebestsolutionisnotlikelytobeamono-solution-itwillneedamulti-faceted,multi-strandapproach.

4.3.9 TherearemanydifficultiesinimplementingSuDSapproachesinLondon.Theseincludelegalandregulatoryproblemsinregardtotransferof‘ownership’oftheredirectedstormwaterfromThamesWater(TW)tomyriadpropertyandlandownersandroadandhighwayoperators.ManyofthesestakeholdersdonothavetheexperienceandhencethecapacitytotakeonthisresponsibilityandwouldneedtobeassistedbyTWtodevelopthiscapacity–asanalternative,TWcoulddevelopanewbusinessthatcanprovideinstallationandmaintenanceofinstalledfacilities.TWconcludedfromthe2009studythatthecostswerehighandthatitwouldtakealongtimeandbetoodisruptivetoeffecttheSuDSoption.NoattemptwasmadetoincludethewiderbenefitsofusingSuDS.

4.3.10 Nonethelessurbanredevelopmentingeneralprovidesasignificantopportunitytoincrementallyimplementan,arguably,moresustainableandadaptablephilosophyofgreeninfrastructuretomanagesurfacewaterandthiswillhappeninevitablyinLondon.Itisdesirabletoconsiderredevelopmentas‘newbuild’andtoapplyfarmorestringentSuDSprinciplesthan‘like-for-like’surfacerunoffcontrol.Thescaleofredevelopmentissuchthatinmanyurbanareassuchanapproachcouldtransformthedrainagecharacteristicsofsome10%ofurbancoreareasoveraperiodasshortas10yearsand,onaverageinNorth-WesternEurope,inaperiodof50yearstimeabout80%-90%oftheurbanareawillhaveundergonesubstantialredevelopmentactivities.

4.3.11 SuDSarethebetteranswertotheeffectofclimatechange.ItisexpectedthatLondonwillsuffermorefrequentlyfrommoreintensiverainstorms,moredroughtsandmoreheatstress.Greeninfrastructurehelpstocopewithallthreeandisflexibleovertheperiodofseveraldecades,whiletheTunnel,onceinstalled,lacksflexibility.InadditionGIhasasmallercarbonimpactbothduringconstructionandincontinuingoperation.

4.3.12 Sincethesestudieswereundertakenalotmoreworkhasbeenforthcominglookingatthemulti-functionalvalueofmanagingstormwaterusinggreeninfrastructure(GI)andSuDS.IntheUSAandnowintheUK,newtoolshavebeendevelopedshowingthattheaddedeconomicvalueofusingGIinsteadofnewsewerscanbeprodigious–some$3bninPhiladelphiaforexample.SuchaddedvalueishighlysignificantgiventhecurrenteconomicclimateandcouldbeveryvaluabletothelocalcommunitiesacrossLondon.

4.3.13 Giventhelatestideasaboutmulti-functionalandmulti-valueGIusedinconjunctionwithsurfacewatermanagementnowemerging,thereistheopportunitytobothimprovethequalityofthewaterintheRiverThames,andbyusingGItomanagethestormwaterclosertosource,simultaneouslyaddgreeningtothelocalareaatpotentiallylowercostthanthatofconnectingsomeofthelocalCSOsintothenewThamesTunnel.ThesourcecontrolstudyalreadyundertakenfortheThamesTidewayTunnel(TTT)hasshownthatstormwaterdisconnectionisfeasibleandthatthemainimpedimenttoitsuseiscostcomparedwiththenarrowlydefinedrangeofbenefits.TheThamesWaterstudyhoweverfailedtoincludetheknownaddedvalueoftheotherpotentialbenefitsofusingsourcecontrolinsteadoftheendofpipestoragetunneloption.

4.3.14 ItisarguedextensivelyintheTTTdocumentsthatmanyofthesewersinLondonare,effectively,runningalmostfullindryweatherand,asaconsequence,needtobeincreasedin


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requiredbyEuropeanandnationallegislationwithinanacceptabletimescale.Theoriginalgovernmentdecisionof2007hasbeenovertakenbyalarmingincreasesincostsaswellasbydevelopmentsinsustainabledrainagepractice.AssumptionsmadethenthatonlyafulllengthtunnelcoulddelivertherequiredreductioninsewagedischargesintotheTidewayneedtoberobustlychallengedifpublicvalueformoneyistobeassured.

5.1.7 ThedraftNPSdocumentconsidersdecentralisationofwastewatertreatmentinfrastructureinoneparagraph(2.413).Itdismissesadecentralisedapproachtowastewatertreatmentasmostappropriateforsmaller,dispersedruralcommunities.Suchanassessmentrevealsalackofinterestorunderstandingofglobalinitiativesinlookingatappropriatealternativesforclosingthecycleofwater,nutrientsandenergyandreducingtheenvironmentalfootprintofcities.Scientificevidenceisclearthatadaptabilityinthelongrunwillbereducedbycentralisingthetreatmentinfrastructure.

5.1.8 ThedocumentstatesthatitistheGovernment’spolicytoencouragetheuseofSuDSwhereverpossible,andthatthispolicywasstrengthenedinTheFloodandWaterManagementAct2010.AppendixEoftheNeedsreport,titled‘PotentialsourcecontrolandSuDSapplications’,concludesthat,inthecatchmentswhichcomprisedthestudyarea,itwastechnicallyfeasibletoretrofitstormwaterdisconnectionmeasuresusingSuDS,whichcouldpotentiallybeeffectiveatreducingtheCSOspillsintotheRiverThames.However,spilleventswerelikelytoremainabove10eventspertypicalyeareveninareaswherethestrategyismostpractical.WerecognisethesignificantimpedimentstotheutilisationofSuDSintheshorttomediumterm,butmanyofourwitnessesattheevidencehearingsareconvincedthatinthelongtermSuDsshouldbewidelyadoptedinLondon.ItisimportanttoplannowwhereSuDSshouldbeexpectedtocontributetothereductionofstormwaterdischarges.Wehaverecommended,inparagraph4.3.15,thatawiderangingcost-benefitstudyshouldbeundertakentoinvestigatethepotentialmulti-functionalvalueandfeasibilityofretrofittingmainlyGIsourcecontrolmeasuresasanalternativetoconnectingcertainCSOstothetunnel.TheEFRAcommitteehasrecommendedthatDefrashouldundertakewithin12monthsafullassessmentofthepotentialnationalimpactofthewidespreadadoptionofSuDs.Werecommendthat,whatevermightbetheresponsefromgovernmenttotheEFRACommittee’srecommendationforanationalassessment,thecost-benefitstudywecallforshouldprovideanin-depthanalysisfortheBecktonandCrossnesscatchments.

5.2 Thecaseforthetunnel

5.2.1 TheThamesTidewayTunnelappearstohaveanumberofadvantagesoverotheroptionsfordrasticallyreducingthequantityofsewagedischargesintotheRiverThames.

• TheprojectwouldbethesoleresponsibilityofThamesWaterasundertakertodeliver.AnyhybridsolutionwhichreliedinpartonSustainableDrainageSystemswouldmakeaccountabilityforafailuretomeettherequiredenvironmentalstandardshardertoapportion.

• TheentirecostoftheThamesTidewayTunnelmightbefundedbyshareholdersand,therefore,ultimatelybycustomersofThamesWater.Atatimeoftightconstraintsonpublicexpenditurethishasobviousmeritsforgovernment.Theremight,however,beconcernonthepartofshareholdersatthescale,complexityandrisksoftheThamesTidewayProject.TheFloodsandWaterManagementAct2010includes,insection35,provisionforlargeinfrastructureprojectstobedeliveredbythirdpartyinfrastructureproviders,wherethesizeorcomplexityofaprojectthreatens,orislikelytothreaten,theundertaker’sabilitytoprovideservicesforitscustomers.TheThames

5. RECOMMENDATIONS5.1 Planningissues

5.1.1 ThePlanningAct2008introducedanewsystemforissuingplanningconsentforlarge,nationallysignificantprojectstoavoidthedelaysthatoccurredindeterminingapplicationssuchastheSizewellBnuclearpowerstationandHeathrowTerminal5.TheInfrastructurePlanningCommission(IPC)wasestablishedtomakedecisionsonsuchprojects,knownasNationallySignificantInfrastructureProjects(NSIPs)guidedbyNationalPolicyStatements(NPS)whichclarifytheissueswhichtheIPCshouldtakeintoaccountwhenconsideringplanningapplications.TheprovisionsoftheLocalismBill,atpresentbeforeparliament,abolishestheIPCanddecisionswillnowbetakenbytherelevantSecretaryofState,withadvicefromanewMajorInfrastructurePlanningUnit.

5.1.2 AdraftNPSwaspublishedonWasteWaterbyDefrainNovember2010.Forplanningapplicationscoveredbythis,NPSdecisionswillbemadejointlybytheSecretaryofStateforEnvironment,FoodandRuralAffairsandtheSecretaryofStateforCommunitiesandLocalGovernment.However,theThamesTunnelprojectdoesnotcurrentlymeetthedefinitionsinthePlanningActforawastewaterNSIP,sincetheActappliestotheconstructionoralterationofwastewatertreatmentplantswithacapacitytoserveapopulationofmorethan500,000.Whilethetunnelmeetsthepopulationcriteria,itisnotasewagetreatmentworks.ThegovernmentproposestoamendthePlanningActsothatlargescalestorageandtransferschemesarebroughtwithintheplanningregimeforNationallySignificantInfrastructureProjects.TheHouseofCommonsEnvironment,FoodandRuralAffairs(EFRA)Committeehasendorsedthiscourseofaction.

5.1.3 TheDraftNPSonWasteWaternotonlysetsoutGovernmentpolicyonthenationalneedforwastewaterinfrastructure,identifyingspecificcriteriaforprovinganyproject’sneeds,butalsosetsout,inChapters3and4,materialinsupportoftheneedscaseforthetwoLondonNSIPs,oneofwhichistheThamesTunnel,thattheGovernmenthasalreadyassessedasmeetingtheseneeds.

5.1.4 IntheEuropeancontextanNPSonWasteWateronlyisexceptional;manycountrieshavemovedtointegratedplansforsurfacewater,groundwater,wastewaterandwaterqualityandwaterresourcesplanning.

5.1.5 TheEFRACommitteehasrecommendedthatthedraftNPSberevisedtoproduceapurelygenericdocumentbyremovingChapters3and4onthereplacementoftheDeephamsSewageTreatmentWorksandtheThamesTunnel.DeframaywishtoprovidematerialinanannexexemplifyingpointsmadeintheNPSbyreferencetospecificschemes,butitshouldbemadeclearthatitdoesnotconstituteinformationtowhichdecisionmakersmusthaveregardwhenconsideringprojectapplications.Webelievethisrecommendationisoffundamentalimportanceandgiveitourfullsupport.TheNationalPolicyStatementshouldnotincludetheThamesTunnelasaspecificscheme.TheStatementshouldbeapurelygenericdocument.

5.1.6 ThedraftNPSappearstobepre-emptingdiscussionofkeyissuestobedeterminedthroughtheplanningprocedures.ItisfortheplanningprocessandnottheNationalPolicyStatementtodeterminewhethertheThamesTunnelmeetsthecriteriaformajorwastewaterdevelopments.Thedraftframeworkdocumenthasrightlybeencriticisedforitsfailureadequatelytoconsideralternativemeasureswhichmightmeetnationalneedsforwastewaterinplaceofconstructingnewinfrastructure.WewouldexpecttheSecretariesofState,advisedbytheMajorInfrastructurePlanningUnit,todemandarigorousanalysisofallalternativemeansofdevelopingtheprojectwhilestilldeliveringwhatis


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some£200meach.

5.3.4 WeweretoldbytheEnvironmentAgencythattheexistingnetworkisrunningatnearfullcapacityincertainpartsoftheseweragenetwork,evenindryweather.ThefactthatcertainCSOsdischargeafterjust2mmofrainisfrequentlycitedasjustificationforthefulltunnel.EachCSOpresentsseparateissuesanditisessentialtodemonstrateineachcasethatonlyconnectiontothetunnelcanprovidetherequiredcontrolatanacceptablepriceandwithintherequiredtimescale.

5.3.5 TheproposedThamesTidewayTunnelProjectispredictedtoreducetheannualvolumeofstormsewagedischargesintotheThamesby93%,ofwhichoverhalfwillbeachievedbytheworkalreadyinprogressontheLeeTunnelandtheupgradingofthefiveSTWs.Thecostofconstructingthe7kmLeeTunnel(£635m)andupgradingthefiveSTWs(£675m)isexpectedtoamounttosome£1.3billion.Itisevident,therefore,thatthenextstageoftheThamesTidewayTunnelProject,theconstructionofthefulllengthtunnelof23kilometres,atacostofapproximately£3.6billion,appearstoofferlessvalueformoney.Itisexpectedtoreducestormsewerdischarges,whichbeforethecommencementoftheThamesTidewayTunnelProjectamountedto39millioncubicmetres,from18millioncubicmetresto2.6millioncubicmetres.AfterthetunneliscompletetherewillstillbeperiodicdischargesfromtheSewageTreatmentWorksandapproximately2.6millioncubicmetresdischargedannuallyfromCSOs.TheannualnumberofCSOdischargeswouldfallfromanaverageof60ayeartofourorless.

5.3.6 WeweretoldbyThamesWaterthatiftheextendedworksatMogdenhadbeeninplacetherewouldhavebeenfiveoccasionsovertheprevious13yearswhenanoverflowwouldhavebeenmadefromMogdenSTW,withatotalestimatedvolumeofsome3.3millioncubicmetres.AsthissewagetreatmentworksdischargesintothewesternreachesoftheTideway,itsoverflowsmighthavepotentiallymoreadverseimpactsthanoverflowsofuntreatedsewagefromtheothersewagetreatmentworkssiteddownstream.

5.3.7 TheEnvironmentAgencyhasassessed10CSOsusinglimitedaccuracycomputermodelsasbeingunsatisfactoryintermsofdissolvedoxygenstandards.Thelargestdischargesfromthese10CSOsareattributedtoAbbeyMillsPumpingStationwhichwillbeaddressedbytheLeeTunnel.AllofthesetenCSOsarealsoconsideredunsatisfactoryintermsofaestheticstandardsandsevenareconsideredunsatisfactoryintermsofhealthstandards.ThesetenCSOsareAbbeyMillsP/S,GreenwichP/S,Deptford,HammersmithP/S,FalconBrookP/S,HeathwallP/S,WesternP/S,LotsRoadP/S,RanelaghandActon.NinearetobeconnectedtotheThamesTunnelandonetotheLeeTunnel[seeMap2].WeacceptthatthedischargefromthesetenCSOs,consideredunsatisfactorybytheEnvironmentAgency,mustbeaddressed,thoughwenotethatProfessorChrisBinnie,whowaschairmanoftheThamesTidewayStrategySteeringGroupfrom2000to2006hassuggested,inhisrecentReviewoftheTunnel,thattheremightbenoabsoluteneedtodealwiththedissolvedoxygenimpactsfromGreenwichP/SandDeptford.HisReviewcanbefoundat:http://www.lbhf.gov.uk/Directory/News/ttc.asp.WereferfurthertoProfessorBinnie’sReviewatparagraph5.3.24.

5.3.8 ThesetenCSOs(includingAbbeyMillsPumpingStation)accountfornearly80%ofthetotalloaddischargedfromalltheCSOs.Initspaper,‘An Assessment of the Frequency of Operation and Environmental Impact of the Tideway CSOs’,TheEnvironmentAgencystatesthatiftheseloadswereremoved,therewouldnotbeasignificanteffectondissolvedoxygenfromtheremainingCSOs.

5.3.9 35ofthe36unsatisfactoryCSOsaredesignatedbytheEnvironmentAgencyashavingunacceptableaestheticimpactsand16aredesignatedashavingunacceptablehealthstandards[seeMap3].OnlyoneCSOisdeemedunsatisfactoryforhealthimpactsalone.ThisisHollowayCSOwhichisnottobeconnectedtotheTunnelbuttobecontrolledbydiversionsandgate

Tunnelprojectcharacteristicssuggestthatthismightbeacandidatetobedeliveredusingthisapproach.WeunderstandthatThamesWater,Defra,InfrastructureUKandOfwatarecurrentlyconsideringthepossiblestructureofaninfrastructureproviderforthedeliveryoftheThamesTunnel.

• Thetunnelcouldpossiblybedeliveredby2020,althoughtheCommissionnotesthattherearedoubtsaboutthefeasibilityofthisprojection,withareasonableexpectationthatitwouldmeettherequirementsoftheUrbanWasteWaterTreatmentDirectiveatleastfortheshortterm:aclaimthattheCommissioncouldnotverify.

• TheThamesTidewayTunnelisastand-alonesolutionwhichdoesnotdependonotherancilliarymeasurestoachievecompliancewithenvironmentalregulatoryrequirements.

• AnysolutionwhichreliesexclusivelyorlargelyonretrofittingSuDS,disconnection,andtheseparationofstormwaterfromseweragesystemswouldtakelongertoimplement.

• TheThamesTidewayTunnelwouldprovidethemostefficientsolutiontoenhancingundergroundstoragecapacityoverawiderangeofcatchmentswithin10-20years.

5.2.2 IftheoptionsforthemediumtolongtermsolutionstotheproblemofunacceptabledischargesintotheThamesTidewaycouldfairlyberepresentedassimplyachoicebetweenaTidewayTunnelorSustainableDrainageSystemsandothergreeninfrastructuremeasuresthenthecaseforthetunnelwouldbeconvincing.Howeverthebettersolutionsinthemediumtolongtermwillinevitablyembracearangeofstrategies,fromsourcecontrolorSuDS,toseparation,storageandtheenhancementoftheexistingsewagenetworkandSTWs.

5.3 Thecaseforamixedsolution

5.3.1 ThereiswidespreadagreementthatSuDShaveanessentialroletoplayandthisisacknowledgedbyThamesWater,theEnvironmentAgencyandallotherproponentsofthetunnel.HoweverbecauseSuDSisnotthewholeansweritistooreadilyassumedthattheonlysolutionavailableistheonewhichdeliversonitsowntherequiredcompliancewithenvironmentalregulations,includingtheUrbanWasteWaterTreatmentDirective.

5.3.2 Yetthetunnelcannotprovidethesolutiontoanumberofthedischargeissues.Someofthehistoricdischargeshavebeen,andcontinuetobe,notfromCombinedSewerOverflowsbutfromSewageTreatmentWorks.ThamesWater’spublicationofJuly2011“Why Does London need the Thames Tunnel?”quotesacasestudyofheavyrainfallduringthefirstweekendofJune2011causing250,000cubicmetresofsewagetobedischargedfromCSOsandatleast230,000cubicmetresofsewagefromtheMogdenSewageTreatmentWorksatIsleworth.ThetunnelwouldhavedonenothingtoreducethedischargesfromtheMogdenSewageTreatmentWorks.

5.3.3 TheThamesWaterpublication,“Why Does London need the Thames Tunnel?”,statesthattheThamesTunnelneedstocontrolorintercept34oftheCSOsthatdischargetotheRiverThamesthroughcentralLondon.Atthetimeofwriting,ThamesWater’smostrecentproposalsallowfor16ofthese34CSOstobedealtwithbyadaptationsoftheexistingsewernetwork,allowingforindirectinterceptionbythetunnel,whilethe35thwillbecontrolledbytheLeeTunnelandthe36thhasalreadybeenaddressedbyalocalscheme.ThemethodsofadaptingtheseCSOsincludetheconstructionofnewoverflowweirsofftheinterceptorsewers,controllingflowsandtheenhancementofthecapacityofSewageTreatmentWorks(STWs).18CSOsaretobedirectlyinterceptedbytheThamesTunnelatanindividualcostequivalentto


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disconnectionofpavedareaand/orendofpipemeasuressuchastheuseofscreens,skimmersandUVdisinfection.

5.3.17 Wenotethat17ofthe36unsatisfactoryCSOshaveprovedcapableofresolutionbyimplementinglocalsolutions,suchastheconstructionofnewoverflowweirs.WewouldexpectadetailedreviewtobeundertakenofwhatotherincrementalimprovementscouldbemadetothedrainageandsewernetworkwithaparticularfocusonthelessfrequentdischargingCSOswhicharetobeconnectedtotheTunnel.TheseincludeStamfordBrookandNorthWestRelief.Itwouldbemostinstructivetocommissionaspecificstudyforsuchinfrequentdischargerstodeterminewhatmeasuresmightbeexpectedtoleadtoanalmosttotaleliminationofdischargesinfuture.

5.3.18 AnyappraisalofthepossiblesolutionstotheproblemofunacceptabledischargesintotheThamesTidewaymustdeterminepriorities.TheThamesTidewayTunnelProjectcommissionedfirsttheconstructionoftheLeeTunnel,atacostof£635million,andtheextensionstotheSewageTreatmentWorks(Mogden£140million,Crossness£220million,Beckton,£190million,Riverside£85millionandLongReach£40million).

5.3.19 TheLeeTunnelwillremovetheworstoffendingCSOatAbbeyMills.Anyalternativetoafulllengthtunnelmust,asafirstpriority,reduceoreliminatethedischargesfromtheremainingnineCSOswhichimpactmostseriouslyonwaterquality(seeparagraph5.3.7).FromWesttoEasttheseareActon,HammersmithP/S,FalconBrooksP/S,LotsRoad,Ranelagh,WesternP/S,HeathwallP/S,DeptfordandGreenwichP/S.

5.3.20 ThenextpriorityshouldbetoreduceoreliminatethedischargesfromtheremainingtenCSOsforwhichtodatenolocalsolutionhasbeenfound.FromWesttoEasttheseareWestPutney,PutneyBridge,Frogmore,SWRelief,Clapham,Brixton,RegentStreet,Fleet,NEReliefandEarlP/S.

5.3.21 OfthenineCSOswhichimpactmostseriouslyonwaterqualityinthefirstprioritycategory,sevenareinthewesternreachesoftheTideway,fromActontoHeathwall.AnotherfourCSOsofthesecondpriorityareinthiswesternreachoftheTideway.TheJacobsBabtiereviewof2006,appointedbyOfwattoreviewtheThamesTidewayProject,recommendedthatapartialtunnelsolution(OptionH),investigatedbutrejectedbytheThamesTidewayStrategicStudy,shouldbeadoptedinplaceofafulllengthtunnel.A9kmlong,7.2mdiameterwesternstoragetunnelwasrecommendedtobebuiltfromHammersmithtoHeathwellPumpingStation.TheBabtiereviewalsorecommendedarangeofmeasurestocomplementthepartialsolution,includingseparation,SuDS,storage,andrealtimecontrol.

5.3.22 Weregretthattheapproachofarangeofmeasureswasnotadopted.TheJacobsBabtieproposalwasrejectedasnon-compliantwiththeUrbanWasteWaterTreatmentDirective.Thefulllengthtunnelisnowpromotedastheonlysolutionwhichcanprovideadequatestorageand,therefore,preventnon-compliantdischarges.Thealternativeoptionsofreducingflowsbyseparation,bygreeninfrastructure,bytheconstructionoflocaldetachedsewagetreatmentworks,bytheconstructionofdistributedstorage,andbytheenhancementoftheexistingsewagenetwork,therebyallowingapartialtunnelsolutionatalowercostorevenanon-tunnelsolution,haveneverbeenadequatelytested.

5.3.23 WerecognisethepracticaldifficultiesoffindingasuitablesiteforoneormorenewlocaldetachedsewageintheBecktonorCrossnesscatchmentsandsuchanoptionwouldinevitablyprovecontroversial.Howevertherearesmallerfootprintplantsinstalledsuccessfullyelsewhereinurbansettings.Ifasitecouldbeidentifiedneartheriver,theby-productssuchasscreeningsandsludgemightberemovedfromthesitebyrivertransport.

modificationsthatdirectCSOoverflowstotheNorthernLowLevel1sewer.

5.3.10 ThecriteriaforassessingtheeffectofCSOdischargesonaestheticqualityislessstraightforwardthanthatforassessingtheimpactondissolvedoxygen.TheEnvironmentAgency’smethodologytakesintoaccountlocation,easeofaccesstothepublicandthenumberofpeopleinthevicinity,aswellasfrequencyandsizeofdischarges.

5.3.11 Whileweaccepttheneedtotakeintoaccountbothaestheticandhealthimpacts,aswellasdissolvedoxygenimpacts,wearenotpersuadedthatthedeterminationofwhichCSOsfailforaestheticstandardsconductedbytheEnvironmentAgencystandsuptorigorousreview.TenCSOshavebeendeemedtopasstheEnvironmentAgency’sownassessmentfordissolvedoxygenimpacts,aestheticqualityorhealthimpactyethavebeenassignedtoCategory2(dischargesthathaveanadverseenvironmentaleffect)ratherthanCategory3(dischargesthatdonothaveanenvironmentaleffect).TheseareShadThamesP/S,EarlP/S,ChurchSt,QueenStreet,SmithSt,KSP,Grosvenor,SavoySt,NorfolkSt,EssexSt[seeMap4].AlloftheseCSOsexceptEarlP/Saretobeadaptedbycontrolwithinthenetworkratherthanbydirectinterceptionbythetunnel.

5.3.12 Thejustificationforoverridingtheevidencehasbeengiventousas‘basedonvisualobservationmadebyThamesWater,EnvironmentAgencyandduetopubliccomplaintsreceived’.ThiscallsintoquestionthescientificrigourandvalidityofthewholeassessmentexerciseconductedbytheEnvironmentAgencywhichscoresandrankseachCSOonacceptedcriteria,onlyforvisualobservationsandpubliccomplaintsultimatelytodetermineifaCSOisassessedtobesatisfactoryorunsatisfactory.

5.3.13 Twoofthe18CSOswhicharetobedirectlyinterceptedaredesignatedunsatisfactorybecausetheyareconsideredtohavefailedtomeetaestheticstandardsonly(RegentStreetandEarlP/S).

5.3.14 Insummarythereareatotalof36CSOsassessedasunsatisfactory.Ofthe18CSOstobeinterceptedbytheThamesTunnel,6aredeemedtobeunsatisfactoryfordissolvedoxygen,aestheticandhealthstandards,2fordissolvedoxygenandaestheticstandards,8forhealthandaestheticstandardsand2foraestheticstandards.AbbeyMillsP/S,whichistobecontrolledbytheLeeTunnel,wasdeemedunsatisfactorybecauseofdissolvedoxygenandaestheticstandards.Ofthe17CSOswhicharetobecontrolledwithinthenetworkandbyalocalscheme1CSOwasconsideredunsatisfactorybecauseofdissolvedoxygen,healthandaestheticstandards,3CSOswereconsideredunsatisfactoryonaestheticandhealthstandards,12onaestheticstandardsonlyandoneonhealthstandardsonly.

5.3.15 Itiscruciallyimportantthatthereisfullconfidenceinthemethodologyfortheseassessments.ThecostimplicationsofthesedesignationsarefarreachinganditisthereforeessentialthatthepragmaticapproachadoptedfordeterminingwhetheraCSOhasadverseenvironmentalimpactsisreplacedbyamplemonitoringofresults,adecentdataanalysis–includingtheuseofvalidatedmodels-andameasurewhichcanbepreciselycalculated.Thisshouldthenbelinkedtoanuncertaintyassessmentlinkedtoclearestimatesofcostsandbenefits.

5.3.16 ThehealthstandardsshouldbereviewedbytheChiefMedicalOfficertodeterminewhethertheseappropriatelyreflecttheassociationbetweenCSOspillsandelevatedhealthrisk.WhilenoCSOistobeinterceptedtomeethealthstandardsalone,eightaretobeinterceptedtomeetbothhealthandaestheticstandardsandtwoaretobeinterceptedtomeetaestheticstandardsalone.WhilethismayleadtodesirableimprovementstothequalityoftheTideway,theconceptofBestTechnicalKnowledgeNotEntailingExcessiveCost(BTKNEEC),whichisstipulatedintheUrbanWasteWaterTreatmentDirective,mightsuggestamorecosteffectivesolutiontomeetthehealthandaestheticobjectivesthantheconnectionofthesetenCSOstoafulllengthtunnel.SomeoftheoptionsmightincludesourcecontrolmeasuresbySuDSand


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restrictiveway.ItistheCommission’sunderstandingthattheEUDirectiverequirespollutiontobereduced,noteliminated,andthatitisuptomemberstatestodetermineprescribedlimitsfortheecologicalhealthofrivers.Inthecaseoftheecologicalstandards,theTTSSmayhavesetthestandardstoohighintheearly2000’stodeliveraschemetodaythatdoes‘notentailexcessivecost’—anotherimportantcomponenttointerpretingtheEUDirective.TheCommissionalsofindsthatasidefromtherisingcostconsiderationofthefull-lengthtunnel,thereisaneedtoexaminewhethergreeninfrastructuretechnologymayalleviatetheconditionsthatcauseandexacerbateCSOs.

• Therefore,theCommissionrecommendsthatthe2007MinisterialrequestofThamesWatertopursueafull-lengthstoragetunnelbereconsidered,sothatthefullrangeof‘besttechnicalknowledge’optionsavailabletomanagestormwaterareevaluatedwithequalconsiderationasthetunnelinmeetingcompliancewiththeUrbanWasteWaterTreatmentDirective.TheCommissionalsoencouragesDefratoinformtheEUproceedingsfortheneedforanenvironmentalandeconomicreassessmenttoensurethatnotonlystormwateroverflowissuesareaddressedbutalsofloodingandwidersocietalbenefits,andthattheoptionspursueddonotentailexcessivecostforthebenefitsaccruedintoday’seconomicclimate.

5.3.24 WehavenotedwithinteresttherecentReviewoftheTunnelproducedbyProfessorChrisBinnie,whochairedtheThamesTidewayStrategyGroupfrom2000to2006.HenowbelievesthattheWesternTunnel,connectingwithActonandextendingtoHeathwall,shouldberevisitedinthelightoftheimprovementstobedeliveredbytheLeeTunnelandtheupgradingoftheSewageTreatmentWorks.Healsosuggeststhatpresentestimatesofprojecteddryweatherflowsareoverestimated,andthatsomeoftheenvironmentalstandardsareincertainrespectsinappropriate.Hisfullreviewcanbefoundat:http://www.lbhf.gov.uk/Directory/News/ttc.asp

5.3.25 Wewelcomethiscontributiontothedebateonthecaseforafulllengthtunnelandagreethattheremustbearigorousre-appraisalofthecost-benefitsofthepreferredscheme.

5.3.26 Duetothefocusonthefulllengthtunnel,precioustimehasbeenlosttoretrofitSuDSanddisconnectpavedsurfacesfromthecombinedsewersysteminordertoreducethetotalCSOvolume.

5.3.27 Duetothesubstantialbudgetrequiredfortheconstructionofthefulllengthtunnelhardlyanybudgetcanbemadeavailableoverthenextdecadesfortheimplementationofothercomponentsofamixedsolution,suchasforfloodriskreduction,withoutspendingconsiderablymoremoney.

5.3.28 Therehasbeennopublicinformationabouttheenergyandcarbonimpactofthetunnel.DefratoldusthattheyexpectedOfwattorequirethisonlyatthenextassetmanagementplanning5yearreviewin2014.Webelievethatthereneedstobeanassessmentmadeoftheenvironmentalimpactofthetunnel,incomparisonwithalternativesolutions,beforeanydecisionistakenonitsconstruction.

5.3.29 WebelievethatthereneedstobeanewjointgovernancestructureintheCapitaltosuccessfullydevelopanddeliveranintegrated,longtermapproachtoaddressingLondon’sdrainageandurbanwatermanagementneeds.ThisshouldbringtogetherThamesWater,theEnvironmentAgency,Defra,theGLAandtheLondonboroughsandotherkeygroupssuchasCCWater.

5.4 Theinfractionproceedings

5.4.1 Annex1oftheUWWTDstatesthatthedesign,constructionandmaintenanceofcollectingsystemsshallbeundertakeninaccordancewiththebesttechnicalknowledgenotentailingexcessivecosts(BTKNEEC).TheBTKNEECprovisionseekstoensurethatthebestpossibletechnicalknowledgeisusedtopreventenvironmentaldamagebeingcausedfromwastewaterdischarges,uptothepointwhereanincreaseintheleveloftechnologyleadstoanexcessivecostcomparedtothelowerleveloftechnology.Inotherwords,thecostofaschemeusing‘besttechnicalknowledge’becomesexcessiveifalesscostly,lowertechnology-basedschemeisequallycompliantwiththeUWWTD.

5.4.2 InDefra’sregulatoryimpactassessmentforsewagecollectionandtreatmentforLondoninMarch2007,itstatesthat:

“The Directive recognises that overflows will occur, as it is not possible to construct collecting systems and treatment plants so as to treat all waste water during situations such as unusually heavy rainfall. It therefore requires member states to decide on measures to limit pollution from storm water overflows. It is considered there is some flexibility in terms of the measures we can consider and apply to limit pollution from storm water overflows.”

5.4.3 Giventhesetwoconditions,theCommissionfinds,asmanyoftheothertestimonyprovidedtotheCommissionalsosupports,thattheUK’simplementationoftheUrbanWasteTreatmentDirective1991/271/EECandtheWaterFrameworkDirectivehavebeeninterpretedina


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includesresearchonimprovedconceptsforurbanwatermanagementandbettermethodsforurbandrainagedesignandwaterqualitycontrol.

Secretariat

PeterSmith LondonBoroughofHammersmithandFulham

AlexKennaugh NaturalResourcesDefenseCouncil

TomConniffe LondonBoroughofHammersmithandFulham

DrLouiseWalker EcoFuturesLtd

ThemembersoftheCommissionexpresstheirdeepgratitudetotheaboveforalltheassistancetheyhavegiveninproducingthisreport.

APPENDIXB Bibliography

ThamesTunnelStudiesandReports

TheMainThamesTidewayTunneldocumentation:

• ThamesTidewayStrategicStudy–SteeringGroupExecutiveSummary(ThamesWater,February2005)

• ThamesTidewayStrategicStudy–SupplementaryReporttoGovernment(ThamesWater,November2005)

• ThamesTidewayStrategicStudyIndependentReview–Phase1FinalReport(OFWAT/JacobsBabtie,February2006)

• TTSSSummaryReport:TacklingLondon’sSewerOverflows(ThamesWater,December2006)

- Anassessmentandvaluationofenvironmentalbenefits(Eftec,December2006)

- Anassessmentandvaluationofenvironmentalandsocialimpactsandmarketbenefits(Entec,December2006)

- TidewayTunnelCostBenefitAnalysis(NERA,December2006)

• RegulatoryImpactAssessment,SewageCollectionandTreatmentforLondon(Defra,March2007)

• SiteSelectionbackgroundpapers(ThamesWater,May2009)

• ProjectOverview(ThamesWater,Summer2010)

TechnicalStudies:

• Tideway–RefinementofOptionA(FaberMaunsell,August2004)

• Connections–CFDModelling(ThamesWaterR&T,November2004)

• Land&PlanningReports(Cascade,2004)

• BudgetCostsphases5to7(ECHarris,2004)

APPENDIXA MembersoftheThamesTunnelCommission

Chairman–TheEarlofSelborneGBEFRS

LordSelbornehassatintheHouseofLordssince1972.HechairstheFoundationforScienceandTechnologyandisaformerChairmanoftheLordsSelectCommitteeonScienceandTechnology.HeisthecurrentChairmanofthePartnersBoardofLivingwithEnvironmentalChangeandhasbeenPresidentoftheRoyalGeographicalSocietyandChancelloroftheUniversityofSouthampton.

CommissionMember–ProfessorRichardAshley

ProfessorAshleyisProfessorofUrbanWateratSheffieldUniversityandaCharteredCivilandEnvironmentalEngineer.Heisrecognisedinternationallyforhisworkoncomputermodelingoftheperformanceofsewersystems.HeholdsresearchpostsatLuleatechnicaluniversityinSweden;theUniversityofBradfordandUNESCOIHEDelft,Netherlands,andwasamemberoftheDTIteamthatundertooktheForesightstudiesintofuturefloodrisksintheUK,anadvisertotheinquiryintoWaterManagementintheUKin2006,thePittreviewoftheUKfloodsof2007.HehasmanyyearsexperienceinsustainabilityassessmentandnowworksonseveralEUprojectsonfloodresilienceandadaptationtoclimatechange.HealsoadvisesOECDonwaterinfrastructure,workswithAustralianandUSpartnersonwatersensitiveurbandesignandfloodriskworldwide.

CommissionMember–HenryHenderson,NaturalResourcesDefenseCouncil

HenryHendersonisthedirectorofNRDC’sMidwestoffice,whichopenedinChicagoin2007.BeforejoiningNRDC,HenryservedasapartnerintheChicago-basedenvironmentalconsultingfirmPolicySolutionsLtd.HenrywasthefoundingcommissionerfortheCityofChicago’sDepartmentofEnvironmentfrom1992to1998.Ascommissioner,hedevelopedanenvironmentalmissionforthecity,whichincludedthedevelopmentoftheChicagoBrownfieldInitiative,anaturalresourcesrehabilitationinitiative,thecity’senergypoliciesandutilityregulations,andChicago’scleanairinitiativetoimproveregionalairqualitywhilepromotingeconomicdevelopment.HenryservedastheIllinoisassistantattorneygeneralfrom1985to1987.Overthepast10yearshehastaughtenvironmentallawandpolicyattheUniversityofChicago,theUniversityofIllinoisandKentCollegeofLaw.

CommissionMember–DrJeanVenablesCBE

JeanVenablesisaCharteredCivilEngineerandCharteredEnvironmentalistwithanMScinPublicHealthEngineeringandalonginvolvementinwaterandwastewaterengineering,waterpollutioncontrol,waterresourcesissuesandfloodriskmanagement.From1994to2003,shewasChairmanoftheThamesRegionFloodDefenceCommittee.SheinitiatedtheThamesEstuary2100projectandwasanexpertadvisortotheprojectteam.In2006shewasappointedandremainsChiefExecutiveoftheAssociationofDrainageAuthorities.In2008/09,JeanwasPresidentoftheInstitutionofCivilEngineers(ICE)andisnowamemberoftheICEWaterPanelandChairmanoftheICEProfessionalConductCommittee.

Commissionmember-Dr.ir.FransH.M.vandeVen,DeltaresandDelftUniversity

FransvandeVenisleaderoftheUrbanLand&WaterManagementteamatDeltares,theDutchindependentinstitutefordeltatechnology,andheisassociateprofessorofUrbanWaterManagementattheFacultyofCivilEngineeringandGeosciencesatDelftUniversityofTechnology.HeholdsaPhDinHydrologyandisleadingresearchworldwideonlimitingtheenvironmentalfootprintofcitiesandmakingthemclimateresilientandsubsidence-free.This


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FlemingH,HartJ–SevernTrentServices,undated)

• Investigatingandmodellingthedevelopmentofsepticsewageinfilledsewers(RobertBachmann,AdrianJSaul,RobertEdyvean–SheffieldUniversity,2004)

InternationalStudiesandReports

1. ‘TheChicagoGreenAlleyHandbook’(CityofChicago)

2. ‘AGuidetoStormwaterBestManagementPractices:Chicago’sWaterAgenda’(CityofChicago,2003)

3. RooftopstoRivers:Greenstrategiesforcontrollingstormwaterandcombinedseweroverflows(Kloss&Calarusse,NaturalResourcesDefenseCouncil,June2006)

4. London:GardenCity?InvestigatingthechanginganatomyofLondon’sprivategardensandthescaleoftheirloss(LondonWildlifeTrust/GLA,2010)

5. ChangingCourse:DeliveringasustainablefutureforthewaterindustryinEnglandandWales’(SevernTrentWater,April2010)

6. TheEconomicsofEcosystemsandBiodiversity:Mainstreamingtheeconomicsofnature;Asynthesisoftheapproach,conclusionsandrecommendationsofTEEB(TEEB,2010)

7. TheEconomicsofEcosystemsandBiodiversity:AquickguidetoTEEBforlocalandregionalpolicymakers(TEEB,2010)

8. EconomicalCSOManagement,Gundersonetal(Stormwater,May2011)

9. CommunicationfromtheCommissiontotheEuropeanParliament,theCouncil,theEconomicandSocialCommitteeandtheCommitteeoftheRegions:‘Ourlifeinsurance,ournaturalcapital:anEUbiodiversitystrategyto2020’(Brussels,May2011)

10. CityofPhiladelphia:‘GreenCity,CleanWaters’http://www.phillywatersheds.org/what_were_doing/documents_and_data/cso_long_term_control_plan

11. NewYorkCity’sGreenInfrastructurePlanandSurfaceWaterManagementPlan.

• RenewableEnergyOptions(NationalEnergyFoundation,October2004)

• PumpingStudy(KSB,December2004)

• TidewayStormEventSampling(ThamesWaterR&T,December2004)

• TidewayInvestigation(Halcrow)

• Hydraulic,O&MandH&SStudy(WSAtkins)

• UndergroundWorksStudy(FaberMaunsell)

• Settlement&GroundMovementStudy(GCG)

• TreatmentStudy(Binnie,Black&Veatch)

• PumpingStudy(KSB)

• Power(McLellan)

• Screening(ThomsonRPM)

• LitterDisposalPaper(ThamesWaterEngineering)

• ControlSystem(ThamesWaterEngineering)

• RiverQualityStudy(EnvironmentAgency)

• ThamesTidewayStrategy;SustainableUrbanDrainageSystems(SUDS)Study(Binnie,Black&Veatch,November2002)

• ThamesTidewayStrategy;Land,PlanningandEnvironmentStrategicReview(LandUseConsultants&CascadeConsulting,2002)

• ConstructionCostEstimates(ECHarris)

• DerivationofBudgetCapitalCosts(ThamesWaterEngineering)

• DerivationofBudgetOperationalCosts(ThamesWaterEngineering)

Thefollowingcomplementarystudieswerealsocommissioned:

• FishTrial(EnvironmentAgency)

• SCITTER(ThamesWaterEngineeringandR&T,July2003)

• FlowMonitoring(ThamesWaterEngineering)

• CatchmentModelling(ThamesWaterEngineering)

• LiteratureSearch(ThamesWaterR&T)

• Legislation(ThamesWaterLegalDepartment)

Othersupportingdocuments:

• CSOInterceptionReview(EnvironmentAgency,April2004)

• Interim/SmallerScaleMeasurestoAlleviatetheEnvironmentalDamageCausedbytheCSODischarges(EnvironmentAgency,September2004)

• KeyrisksconsideredindevelopingasolutionforLondon’scombinedseweroverflows(EnvironmentAgencyJune2004)

• UseofTetraDeep-BedFiltrationforTreatmentofWetWeatherOverflows(SlackD,


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APPENDIXC Thefollowingorganisationsandindividuals(listedinalphabeticalorder)

responded,inwriting,totheCommission’sopencallforevidence,issuedinJuly2011.

LordBerkeley,ChairmanoftheRailFreightGroup

MrRajBhatiaBArchRIBA,DipTP

ProfessorChrisBinnieMA,DIC,HonDEng,FREng,FICE,FCIWEM.

CityofPhiladelphia

ConsumerCouncilforWater

ComerBrothers

ProfessorJ.BryanEllis,MiddlesexUniversity

EnvironmentAgency

GreaterLondonAuthority

JustineGreeningMP’sWorkingGroup

InstituteofCivilEngineers

SimonHughesMP

MrGrahamKing

LondonBoroughofGreenwich

LondonBoroughofHammersmith&Fulham

LondonBoroughofLambeth

LondonBoroughofRichmond

LondonBoroughofTowerHamlets

LondonBoroughofWandsworth

LondonForumofAmenityandCivicSocieties

LloydsEmergingRisksTeam

MilwaukeeMetreopolitanSewerageDistrict

Ofwat

MrDavidPercivalMICE

PeterboroughRoadandAreaResidentsAssociation

PortofLondonAuthority

ThePutneySociety

SaveKingEdwardMemorialPark

SaveKingsStairsGardensActionGroup

SaveYourRiversideActionGroup

SmartSpongeProductsLtd

StoptheShaft

MsJenniferSlaney

MrGrahamTaylor,BermondseyandRotherhitheEnvironmentGroup

Mr&MrsTaylor

ThamesBank

ThamesWater

WandsworthSociety

WestminsterCityCouncil

WildfowlandWetlandsTrust

APPENDIXD OralEvidenceHearings

Oralevidencewasheardoverthreedays(on17&18Augustand8September)fromthefollowingorganisationsandtheirnamedrepresentatives(inorderofappearance):

ThamesWater:

RICHARDAYLARD,ExternalAffairsDirector

PHILSTRIDE,HeadofLondonTidewayTunnels

MIKEGERRARD,ManagingDirector,ThamesTunnelProject

HOWARDBRETT,WasteWaterPolicyandStrategyManager

DAVIDCRAWFORD,AssistantIntegrationandModellingLead

ConsumerCouncilforWater:

DAVIDBLAND,Chairman,SouthEast

ANDREWWHETNALL,Member,SouthEast

KARENGIBBS,PolicyManager,SouthEast

ThamesTidewayStrategicStudyGroup:

PROFESSORCHRISBINNIE,formerChairman

PortofLondonAuthority:

DAVIDPHILIPS,HarbourMaster(Upper)

JAMESTRIMMER,HeadofPlanningandPartnerships

GreaterLondonAuthorityandTransportforLondon:

STEPHENTATE,AssistantDirector,TransportandEnvironment

KEVINREID,PrincipalProgrammeManager(GLA)

COLINMANN,HeadofBoroughCo-ordination(TfL)

JustineGreeningMP’sWorking Group:

BARRYEDWARDS,TechnicalSub-group

UrbanPollutionResearchCentre, MiddlesexUniversity:

PROFESSORJ.BRYANELLIS

Thamesbank:

LADYDIDOBERKELEY,Director

StoptheShaft:

SIANBAXTER,Chairman

LondonBoroughofHammersmith& Fulham:

CLLRSTEPHENGREENHALGH,Leaderof theCouncil

Ofwat:

KEITHMASON,DirectorofFinanceand Networks

DepartmentofEnvironment,Food andRuralAffairs:

JOHNBOURNE,DeputyDirectorofWater SupplyandRegulation

ANTHONYHYNES

SIMONPARKER

EnvironmentAgency:

DAVEWARDLE,LondonAreaGroup Leader

PAULHICKEY,HeadofLandandWater Quality


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APPENDIXE ListofAbbreviations

Thefollowingabbreviationshavebeenusedinthisreport:

BOD -BiochemicalOxygenDemand

BTKNEEC -BestTechnicalKnowledgeNotEntailingExcessiveCost

CCW -ConsumerCouncilforWater

CSO -CombinedSewerOverflow

Defra -DepartmentofEnvironment,FoodandRuralAffairs

DEP -DepartmentforEnvironmentalProtection

EA -EnvironmentAgency

EC -EuropeanCommission

EFRA -Environment,FoodandRuralAffairs

EU -EuropeanUnion

GI -GreenInfrastructure

GLA -GreaterLondonAuthority

ICE -InstitutionofCivilEngineers

IPC -InfrastructurePlanningCommission

LID -LowImpactDevelopment

NAO -NationalAuditOffice

NPS -NationalPolicyStatement(onWasteWater)

NSIP -NationallySignificantInfrastructureProject

Ofwat -OfficeofWaterServices

P/S -PumpingStation

STW -SewageTreatmentWorks

SuDS -SustainableDrainageSystems(formerly:SUDS-SustainableUrban DrainageSystems)

TTSS -ThamesTidewayStrategicStudy

TTT -ThamesTidewayTunnel

TW -ThamesWater

UWWTD -UrbanWasterWaterTreatmentDirective

WSUD -WaterSensitiveUrbanDesign
