1
11
The future for stormwater The future for stormwater managementmanagement
Richard AshleyPennine Water Group
Department of Civil & Structural EngineeringUniversity of Sheffield
Richard AshleyRichard AshleyPennine Water GroupPennine Water Group
Department of Civil & Structural EngineeringDepartment of Civil & Structural EngineeringUniversity of SheffieldUniversity of Sheffield
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Overview Overview In an uncertain future
Need we change what we have always done?There’s a right engineering way
Inertia of existing systems and paradigmsInstitutional (in)flexibilityCarrots and sticksExamples from Netherlands, USA, Australia and elsewhereIs there room to manoeuvre?What does the future hold?
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What are we trying to achieve?What are we trying to achieve?
Health and welfareQuality of lifePreservation of ecosystems…What are our levels of service?
Climate change means these all change much more rapidly and in a more complex way than we are used to
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Conclusions up frontConclusions up front
Cannot continue as we have doneMixed solutions that are incremental and adaptable are required
Some of these will require separate stormwater managementSome will require disconnectionSome may require new combined sewersSome will require constraints on householders!
However, we do not know which.. as yet
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Why? Why? -- Complexity Complexity
Balancing quantity and qualityThere is no longer A RIGHT engineering wayWhole systems approaches are going to be needed
Outside perspective
water manager
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Current main driver Classification Current main driver Classification standardsstandards
Ecological (surface waters) -high, good, moderate, poor, bad
BiologySupported by water quality, morphology and hydrology + UK standards for pollutants
Chemical (surface waters) -pass, failEuropean standards for priority list pollutants
Groundwater Classification (Quantitative + Chemical) - good, poorWater quality, quantity and significant damage to dependent ecosystems
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Unfortunately stormwater runoff is extremely variable in quality and quantity
Runoff via sewer Direct discharge Comments Substance *Low case
(μg/l) High case (μg/l)
*Low case (μg/l)
High case (μg/l)
Cadmium 0.09 0.19 0.13 0.67 Chloroform (Trichloromethane)
0.02 0.33 0.30 0.50
Chromium 1.6 2.8 4.4 9.4 Highest from housing area
Copper 11.1 17.3 15.9 206 Di(2-ethylhexyl)phthalate
5.4 33.9 69.8 69.8 Highest from housing area
Dichloromethane 0.6 4.5 1.0 9.1 Fluoranthene 0.02 0.03 0.31 0.31 Lead 4.6 1.9 7.9 85.2 Mercury 0 0.19 0 0.58 Nonylphenols 0.88 2.43 1.8 4.9 Naphthelene (PAH) 0 0.16 0 0.37 Nickel 2.4 4.3 4.2 8.1 Nonylphenol ethoxylate
10.6 181.1 20.2 449.0
PAHs 0.46 0.63 1.56 1.56 Zinc 23.0 50.8 35.7 445.0
UKWIR 2004
From direct stormwater discharge
From residual after storage of first flush
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Uncertainty and standards
Standards need to be flexible and adaptable > design codes?
Sustainable communities PPS1 & 26
PPS3 > more flexibility on densities?
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New civil engineer 22/09/05New civil engineer 22/09/05
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UKWIR 21st century sewer designUKWIR 21st century sewer designHouse of Lords inquiry into water House of Lords inquiry into water
managementmanagementEnvironmental legislation is the greatest single change driverThe EA are more interested in the environment than peopleOfwat are more interested in costs than value
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Priority substances directivePriority substances directive
Lack of de minimis levels is extremely worrying, making it difficult—if not impossible—to complyunlikely that without realistic target levels—taking into account background levels - can be justified in terms of costswork towards the inclusion of appropriate, science-based de minimislevels in the DirectiveOfwat agrees!!!
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PlusPlus……
Responding to a changing climateGovernment sustainable development aspirations….
At regional spatial strategy, local development documents, with sustainability appraisalsEmphasis here is on local planning authority responsibilities
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Some relevant Projects Some relevant Projects URBEM (EU 5th framework)Daywater (EU 5th framework)WaND – Water cycle management and new developments (UK Sustainable urban environments)INTERREG IIIb:
Urban Water Cycle (UWC)No Rain Water in Sewers (NORIS)FLOWS
LIFE: SMURFAUDACIOUS (adapting existing urban drainage to climate change)EA/BOC project on retrofit SUDS
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ScorePPScorePP
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The Water Balance Model promotes a watershedThe Water Balance Model promotes a watershed--based approach that based approach that manages the natural environment and the built environment as intmanages the natural environment and the built environment as integrated egrated
components of the same watershed.components of the same watershed.
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Targets Targets ……
Good ecological statusEnvironmental flowsProhibited substances
Flows and loads
••But do we really know what the targets But do we really know what the targets are? are? ••Or how well the responses work?Or how well the responses work?
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In the USA they use TMDLsIn the USA they use TMDLs
Recommended BMP Responsible entity
Discourage the presence of resident waterfowl
Residents and property owners, Towns of North Kingstown and East Greenwich
Structural Stormwater Management BMP(s) Town of North Kingstown Agricultural BMPs, including a waste storage structure, roof runoff management.
Farm owner
Water body TMDL Pollutant
Water Quality Target
Natural Allocation TMDL Goal Targeted Beneficial Uses
Accumulated sediment
Increase/maintain lake storage capacity by 53 acre feet
94 % of loading attributable to natural background
5 % decrease in sediment loads from watershed
A. Hiddenwood Watershed, Walworth County South Dakota (February 1999)
Total phosphorus
Increased visitor days/camp site use; decreased incidence of winter fish kills
95 % of loading attributable to natural background
2% decrease in total phosphorus loads from watershed
Immersion recreation; limited contact recreation; warm water semi-permanent fish life propagation
Citizen engagement is one of the main Citizen engagement is one of the main principles of the Clean Water Act and principles of the Clean Water Act and
NPDESNPDES
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New planning of high density communitiesNew planning of high density communities
Everyone wants to live in a mews development
2020
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New modernism in the USANew modernism in the USA
5.5 – 16 units/acre
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Principles Principles
Level of serviceFlood protection should be provided to a minimum level of serviceRisks to people and amenity benefits should be addressed (including safety)
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Principles Principles Sustainability
Drainage systems should replicate the natural rainfall-runoff processes occurring on the site, pre-developmentWater quality treatment should minimise environmental impactEcological benefits should be maximisedDrainage systems should aim to utilise natural resources that can be reused and are energy efficient in terms of constituent products, construction processes and operation and maintenance activities
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Principles Principles
CostA whole life cost analysis of the system should demonstrate cost-effectiveness (through option appraisal) and financial viability (through security of long-term funding)
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Sustainability Sustainability
SUDS = Sustainable Drainage Systems
••May be the better option to use pipesMay be the better option to use pipes
••Whole system life performance!Whole system life performance!
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Responding Responding -- DCLG & Defra, 2006DCLG & Defra, 2006
Big infrastructure Big infrastructure investmentinvestment
Adaptation Adaptation ––incremental incremental ‘‘no no
regretregret’’
Acceptable risk Acceptable risk levellevel
Future acceptable Future acceptable risk levelrisk level
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Defra diffuse pollution study Defra diffuse pollution study programme workshopprogramme workshop
SUDS usually reduce the opportunity for misconnections to occur – as it is obvious if foul inputs are connected into open stormwater systems. Benefits are believed to accrue due to the increasing use of grass-crete for car parks, permeable asphalt, paviours, and grass swales. The SUDS approach to drainage is believed to be the most effective mitigation for road run-off pollution currently available.
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New systems New systems –– should be easiershould be easier
Are there really any?Encouragement to use ‘SUDS’ in preference and piped drainage where SUDS inapplicable
Sewers for adoption, PPS25,,,,,
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Combined Combined vsvs separate drainage separate drainage systemssystems
We all know the problems…
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Deep storage tunnels in USADeep storage tunnels in USA
‘‘approaches address the symptoms not the causeapproaches address the symptoms not the cause’’
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Natural Resources Natural Resources DefenseDefense Council 2006Council 2006“Capturing, retaining, and trying to improve the quality of vast
quantities of urban stormwater runoff is often more difficult and expensive than reducing the amount of stormwater generated from the outset through strategies to reduce imperviousness and maximize infiltration and filtration. ..costs can be decreased when these techniques are incorporated into redevelopment and ongoing infrastructure replacement efforts. Comprehensive stormwater management programs can be used to minimize the effect of impervious surfaces and manage precipitation and stormwater with the use of natural processes. These “green” approaches are often less expensive and more effective than current stormwater and CSO controls…. Newer, flexible, and more effective urban stormwater and CSO strategies are being adopted in North America. Cities are beginning to introduce green infrastructure as a component of comprehensive stormwater management plans aimed at reducing stormwater runoff, CSOs or both. This approach is significant in that it can be used to address the stormwater problem “at the source”
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EU projectsEU projectsNORIS & Urban water cycleNORIS & Urban water cycle
http://www.noris.co.uk/http://www.interregnorthsea.org/project-details.asp?id=1-16-31-7-37-04
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Disconnecting stormwater from
combined systems -
Environmental impact in Wierengerwerf, NL
Sampling before a storm and Sampling before a storm and immediately afterwardsimmediately afterwards
TNO NetherlandsTNO Netherlands
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Short term Short term effectseffects
What is the quality of rainwater in a separated stormwater system?
Field monitoringAcute effectsImpacts on plankton and physico-chemical
Biological : Effects on biota – lab scaleChemical: indicators
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At inlet to ditches and ponds
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Regen 1: zink opgelost
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1015
2025303540
NOR001 NOR003 NOR004
Regen 1: zink totaal
05
1015
2025303540
NOR001 NOR003 NOR004
Ponds total Zn
Pondsbioavailable Zn
Dutch standard
Dutch standard
Before a storm
After a storm
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ToxicityToxicity
Regen 1: Thamnotox
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Blanco RWA001 RWA003 RWA006
%le
vend
na
24 u
ur b
loot
stel
ling
Small crustaceasurvival
blank
4040
Heavy metalsHeavy metals
0
100
200
300
400
500
600
700
800
900
zink iron aluminium strontium koper barium lead
µg/l
RWA1
RWA3RWA6
significant
Not significant
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0
0.5
1
1.5
2
2.5
3
3.5
4
vana
dium
nicke
l
molybd
enum
coba
lt
antimony
arsen
icum
thalliu
m
dyspro
sium
uraniu
mthu
lium
µg/l
RWA1
RWA3
RWA6
Exotic metalsExotic metals
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LocalLocal plastererplasterer washed washed buckets into drain buckets into drain -- ExoticExoticmetalsmetals are are knownknown toto bebepigments/constituentspigments/constituents in in plasterplaster
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Dealing with existing systemsDealing with existing systems
Dense urban areasSewered watercoursesOut-of-sight-……Combined systemsSeparate systems connected to combinedWrong connections
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What are others doing?What are others doing?
In the Netherlands combined sewers are supposed to be separated
- Alkmar estimate saving €80M compared with using CSO chambers
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Dutch 4Dutch 4thth policy plan of Water policy plan of Water Management (NW4)Management (NW4)
By 2006:-separate 60% of rainwater in new developmentsSeparate 20% of existing systems
Water policy for 21st century aims not to transport rainwater over long distances or to purify it
Hence needs to be stored, used and managed at source
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MorraparkMorrapark, zero emission mixed area , zero emission mixed area developmentdevelopment
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BOSTONBOSTON
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BOSTONBOSTON
From one big interceptor ($1.3bn, 1993) to 29 smaller From one big interceptor ($1.3bn, 1993) to 29 smaller schemes ($835M, 2002) schemes ($835M, 2002) -- many disconnections.many disconnections.
Separate stormwater utilities Separate stormwater utilities -- but citizens are on the but citizens are on the management Boardsmanagement Boards
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NEW
RETROFIT
Seattle
Green roads: 91% infiltration and traffic calming
Contractor fines of > $1M for contaminating streams during construction
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Portland OregonPortland Oregon
Transportation estimated to cause 70% of the demand on stormwater systems 44,000 outof 110,000 homes disconnected removing 1 billion gallons a yearHomeowners get signs in gardens
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AbtechMagic spongeNorwalk,
Connecticut
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National Resources National Resources DefenseDefense Council Council (2006)(2006)
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‘‘greeninggreening’’
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From this to From this to ……………………this in 25 yearsthis in 25 years
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Other Nth American studiesOther Nth American studies
Vancouver: ’50-year retrofit of green roofs and infiltration could counteract the effects of climate change and urbanisation’. But the costs will be similar or slightly more than conventional systems for retrofits.New York also proposing a similar approach.Proposals presume there are added benefits and that the approach can be spread over a long period, with incremental development.
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Bradford Bradford –– city regenerationcity regenerationNew inner city canal linking to New inner city canal linking to the networkthe network
DaylightingDaylighting: Better urban design: Better urban designBetter places to live and workBetter places to live and work
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5858
30
5959
6060
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Inlet basinSettling
basin
wetland
Final wetland
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AUDACIOUSAUDACIOUS
Maps are Crown Copyright. All rights reserved. Bradford MDC 100019304
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TonsonTonson CourtCourt Line of old watercourse obliterated by developmentConnected into sewerFlooding from higher ground and from covers in low areaNeed to find original line of watercourse, otherwise massive strorage solutions requiredUse trench trough systems to drain playing fieldsYW need to address sewer flooding problems
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Storage designStorage designSealed trench/trough storage systems the benefits of infiltration were
negligible and without sealing, the systems would act as land drains, lowering the water table and affecting the numerous trees which are located in a preservation area.
Overflow
Connection
Main river
Under drainControl
Trench/Trough
Climate change added 10% to the volume
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Recovery of urban rivers and streamsRecovery of urban rivers and streams
Jonathan Swift noted how quickly a rainstorm could turn the Fleet into a torrent, and what filth it would carry down in its wake:
"Sweepings from Butchers Stalls, Dung, Guts and Blood, Drown'd Puppies, stinking Sprats, all drench'd in Mud, Dead Cats and Turnip-Tops come tumbling down the Flood".
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Fleet RiverFleet River
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URBEM projectURBEM projectprovides new tools, techniques and procedures to enhance watercourses located in urban areas. cover the differing, multi-functional uses of urban watercourses and their adjacent communities provides for those who are involved in urban river rehabilitation, the best and most innovative practice with which to develop a comprehensive rehabilitation scheme that will achieve the “maximum ecological potential”requirements of the WFD. As river rehabilitation involves many aspects the project is targeted at different institutions involved in the enhancement of watercourses at all levels.
Essentially urban rivers are an Essentially urban rivers are an opportunity not a threatopportunity not a threat
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DayWaterDayWater –– EU project EU project http://daywater.enpc.fr/www.daywater.org/DECISION SUPPORT FOR INTEGRATED URBAN STORMWATER MANAGEMENTADSS: Hydropolis interface for the building of the Matrix of Alternatives (MoA) and to the Multicriteria Analysis (MCA),Chemical hazard identification and assessment tool (CHIAT) and vulnerability mapping (FLEXT),Source and flux models in urban stormwater (STORM and SEWSYS)
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DayWaterDayWater Chemical hazard identification Chemical hazard identification and assessment tool and assessment tool -- CHIATCHIAT
Source characterisation
Receptor and exposure identification
Hazard identification Expert
judgementHazard
assessment
Case specific information
Observed and potential present constituents
Inherent properties Measured data
Toxicity
Grouping
Addition
Legislation
Navigation
What is and can CHIAT
AcknowledgmentsBackground
RICH Tool
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DayWaterDayWater Chemical hazard identification Chemical hazard identification and assessment tool and assessment tool -- CHIATCHIAT
Source characterisation
Receptor and exposure identification
Hazard identification
Expert judgement
Hazard assessment
Case specific information
Observed and potential present constituents
Inherent properties Measured data
Toxicity
Grouping
Addition
Legislation
Navigation
What is and can CHIAT
AcknowledgmentsBackground
RICH Tool
Methodology for evaluating and Methodology for evaluating and prioritising environmental risks prioritising environmental risks associated with chemical constituents in associated with chemical constituents in stormwaterstormwater
Selected stormwater priority pollutants Selected stormwater priority pollutants (SSPP)(SSPP)
Database of SSPPDatabase of SSPP
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Tidan – pollutant source existing system & leaking/exfiltrating combined sewers
0%
20%
40%
60%
80%
100%
Cu Zn Pb Cd tot-P tot-N PAH
roofroadwetdeposition
7474
Relative sourcesRelative sources
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Nutrient pollution sourcesNutrient pollution sources
7676
2 in 1 liner2 in 1 liner
Sanitary flowsSanitary flows
Excess storm Excess storm flowsflows
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Linden, Linden, HannoverHannover
Hannover started to separate the existing combined system in 1970s to reduce CSOs to the rivers Ihme and Leine. Today about 2/3 of the system is separated
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Inolet
Germany
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Modelling Modelling
The total area combined, representing the sewer system 25 years agoThe present sewer system with both combined and separate areas
Measurements made on the outflow from the INOLET system shows reduction efficiencies of 20–50 % for different pollutants
8080
Original system Original system
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Original source of pollutantsOriginal source of pollutants
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Stormwater pollutant sourcesStormwater pollutant sources
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Pollutant input to receiving water after partial separationPollutant input to receiving water after partial separation
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Findings Findings
Most P load comes from sanitary sewage in WWTW effluent and CSO spills (10%)After separation CSO spills reduced and only 2% comes from stormwater inputs
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Before and afterBefore and after
Separation increases Separation increases the loads of Cu, Zn, the loads of Cu, Zn,
PbPb, , CdCd, PAH, PAH
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Other findingsOther findings
INOLET filters reduce the overall system pollution load emitted by 21%, 30% and 29% for copper, zinc and PAHbrake wear is the dominant source for Cusources of Zn pollution are mainly corrosion from roofs and tyre wear
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Other pollutantsOther pollutantsBOD and COD behave similar to total P - with the sanitary wastewater flow. Hence, the total discharges of BOD and COD will be lower for the new system compared with the old TSS behaves similarly to Zn. Thus, the total discharges to the recipient of TSS will be higher for the new system compared with the old. The effect of INNOLET filters on TSS load will also be similar to zinc with a reduced discharge of about 30% compared with the new system
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Public Public ENGAGEMENTENGAGEMENTin Los Angelesin Los Angeles
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Public ENGAGEMENTPublic ENGAGEMENTin Los Angelesin Los Angeles
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International workshop on stormwater International workshop on stormwater management into the futuremanagement into the future
an integrated urban water management approach should be considered in keeping with global movements to IUWM and Integrated Water resources Management (IWRM)In the UK only one aspect (receiving water ecological status) has been considered and not the overall need to adopt an IWRM approach.whilst some storage would inevitably be needed to be engineered, alternative source controls should be looked at in greater depth.the very limited accuracy of sewer system quality models, and possible over-reliance on these effectively makes any comparison of options unreliable, as certain options rely on better drainage system simulation modelling than has been achieved
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Integrated approachesIntegrated approaches
From IUD to WSUD and LID >>>
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USE
Potable water supply and treatment plant
Discharge
Hot water system
Shower and bathroom taps
Clothes washing
Toilet flushing
Garden irrigation
Built environment Natural environment
Natural environment
Built environment
Human consumption - kitchen
MINIMISE
MINIMISE
REUSE
Discharge
Sewage treatment
plant (STP)
Rosebery RTA Site Redevelopment
Treatment
Header TankTreated water for toilet reuse
To sewer
Supplementary Mains water
Collection of light greywater
Overflow to sewer
WSUDWSUD
Tony Wong
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9393
USE
Potable water supply and treatment plant
Discharge
Hot water system
Shower and bathroom taps
Clothes washing
Toilet flushing
Garden irrigation
Built environment Natural environment
Natural environment
Built environment
Human consumption - kitchen
MINIMISE
MINIMISE PROTECT & ENHANCE ENVIRONMENT
REUSE
Discharge
Stormwater
treatment
Train
Sewage treatment
plant (STP)
Rosebery RTA Site Redevelopment
NAB Building, Melbourne Docklands
WSUDWSUD
Tony Wong
9494
Blacken
Ridge
Bioretention
Basin
Baltusrol
Estate
(Australand)
Victoria
Park
(Landcom)
Cremorne
Street
(City
of
Yarra)
Victoria Harbour, Melbourne Docklands
(Lend Lease)
Baltusrol Estate(Australand)
Bourke Street Tree Planters (Lend Lease)
Building Bioretention Planters (Portland, Oregon, USA)
Hampton Park Wetland (Melbourne Water)
Lynbrook Estate Wetland (VicUrban) All Nations Park Wetland (City of Darebin)
NAB Building Forecourt Wetland
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Understand the drivers to Understand the drivers to understand the preferred solutionunderstand the preferred solutionIn the UK increasing the value of assets is a major driverBut….
Now the main driver is the WFDIn the future it will be climate change
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Why the future is differentWhy the future is different
We cannot predict what will happen with any confidenceAdaptable solutions that are incremental mean we can try them out and abandon those that do not deliverBig investments may lead to regrettable solutions….. As we learn more
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European Water Directors report European Water Directors report 20052005
Reference (ecological) conditions for compliance will need to be dynamic:
Adaptation of the classification scales – by adjusting reference conditions - to accommodate effects that cannot be mitigated
Effects not understood – need long term monitoring of minimally impacted sites
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Recommended approachRecommended approach
MUSIC, or SWMM (Strecker version) not microdrainage
Quality of flows data collection and modelling explicitly accounting for uncertainties.
CIRIA manuals and SUDS retrofit
Quantity of flows modelling.Specifically accounting for exceedence flow management.
4. Identify technical and non-technical options for alternative management of the major sources. Carry out flood risk assessments and pollution risk-based assessments
SUDS retrofit (see below)Specification of sources of funding and regulations.Identify service levels and risks.
3. Identify opportunities and constraints to changing the main non-foul inputs
AUDACIOUS and WaND for guidance
Ontologies of stakeholder responsibilities and likely cost burdens
2. Identify stakeholders at the various levels and engage with those relevant to the sources of non-foul inputs
EU infil/exfil projectsFlow records
Monitoring and data records1. Identify sources of non-stormwater inputs
Detailed information source
HowStep
50
9999
Approach Approach -- 22
Australian approachFully integrated approach across the water cycle
9. Assess options for implementing a holistic IUWM or IWRM approach
Australian practice and LID in the USA
Incorporation of approach into the urban planning process (possibly as part of an urban regeneration process)
8. Assess options for implementing changes as part of a WSUD approach
Daywater or similarIdentify land use and space opportunities from local to catchment scale
7. Assess implementation options – using an incremental and adaptable approach
SWARD and SNIFFER project
Multi-criteria approach accounting for technical, social, environmental and economic factors.
6. Using a more detailed multi-criteria assessment approach identify the most sustainable option
SWARD, WLC sewerage project, WaND
Whole life assessment of existing and proposed options – using discounted costings
5. Using a Whole Life Cost approach assess the most cost-effective option
100100
LessonsLessonsNo one yet knows how to do it..What are the targets?What are the means?By the way…. these will both change as drivers change…Responses need to be flexible, resilient and adaptable and one size will not fit all
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In futureIn future
Expect that even in 10 years time we will know more than we do now. If so, then it is important to avoid getting locked into one single solution – sustainability is about recognising uncertainty in the future and delivering solutions that are flexible and adaptable. A single type of solution is not one which is now being defined as a ‘no regret’ solution.
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Good things about disconnection Good things about disconnection Encourages greater local awareness and responsibilityBetter for local ecosystems – green roofs provide other benefits as wellMore efficient sewage treatmentEssential component of an integrated solution approach – especially where there is water stress
Water cycleInfrastructure systemsNatural systems
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Bad thingsBad things……
More riskyHealthFlooding and downstream impactsLocal ecosystemsWrong connectionsLack of confidence in SUDS performance (still an art not a science)Lack of public willingness to engage
Loss of transport capacity in existing combined sewersTransference of responsibilities
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andand……
Our current institutional systems cannot cope with it
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However However
There is an inevitability about disconnection – it is here for new buildIncremental - as urban areas are regenerated (e.g. Los Angeles)It is surely part of the promotion of aesthetic and urban area enhancement (e.g. Malmo)
106106
Finally Finally
We need more R&D in this areaWe cannot yet design ‘quality’
More proper public and other stakeholder engagementHonesty across the service providers and regulators – Government should take more of a leadUKWIR proactive
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““I never knew sustainable urban I never knew sustainable urban drainage was so interestingdrainage was so interesting””