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

22

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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33

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

44

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

3

55

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

66

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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77

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?

5

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1010

New civil engineer 22/09/05New civil engineer 22/09/05

6

1111

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

1414

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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1515

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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2121

New modernism in the USANew modernism in the USA

5.5 – 16 units/acre

2222

12

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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)

2626

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,,,,,

3030

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

05

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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3939

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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4141

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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4343

Dealing with existing systemsDealing with existing systems

Dense urban areasSewered watercoursesOut-of-sight-……Combined systemsSeparate systems connected to combinedWrong connections

4444

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

4848

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

5252

National Resources National Resources DefenseDefense Council Council (2006)(2006)

27

5353

‘‘greeninggreening’’

5454

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.

5656

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

29

5757

5858

30

5959

6060

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6161

Inlet basinSettling

basin

wetland

Final wetland

6262

AUDACIOUSAUDACIOUS

Maps are Crown Copyright. All rights reserved. Bradford MDC 100019304

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6363

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

6464

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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

6666

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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

7272

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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7373

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

38

7575

Nutrient pollution sourcesNutrient pollution sources

7676

2 in 1 liner2 in 1 liner

Sanitary flowsSanitary flows

Excess storm Excess storm flowsflows

39

7777

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

7878

Inolet

Germany

40

7979

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

8282

Stormwater pollutant sourcesStormwater pollutant sources

42

8383

Pollutant input to receiving water after partial separationPollutant input to receiving water after partial separation

8484

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

8686

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

9090

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 >>>

9292

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

9696

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

49

9797

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

9898

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.

102102

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

52

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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

104104

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

54

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““I never knew sustainable urban I never knew sustainable urban drainage was so interestingdrainage was so interesting””