Wessex Water’s Grid - overview · 04/02/2017  · 2 Wessex Water’s Grid - overview • Wessex...

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Wessex Water’s Grid - overview

• Wessex Water’s largest ever construction project• Valued at over £220M• Commenced in 2010, due to complete in 2017• Long term strategic vision to address existing and

potential water supply and customer issues:• Security of supply and resilience• Reduction in abstraction licence• Supply demand balance• Quality issues• Presentation not focussed on modelling but Project

contains all the elements used in modelling

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Presentation structure

• Development of the concept– Strategic objectives– What do customers want?– Why do we need a grid?– Is it the best solution?– How catchment management fits in

• Design & construction– Team structure– Project objectives & Scope of works– Environmental constraints– Concept development– Programme

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Strategic objectives

• To address customer priorities• To align investments with our strategic direction statement• To resolve three key issues:

– Meeting demand for water over next 25 years– Improving security of supply– Maintaining drinking water quality

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What do customers want?

Willingness to pay for improvements

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

Leakagereduction

Security ofsupply

Reducing

greenhousegas em

issions

Drinking w

aterquality

Taking water

from rivers

Internal flooding

River w

aterquality

Beaches &

bathing waters

External

flooding

Pollution

incidents torivers

£ pa

for 1

0% c

hang

e

Indicative cost benefit ratios

0

0.5

1

1.5

2

Leakagereduction

Security ofsupply

Reducing

greenhousegas em

issions

Drinking w

aterquality

Taking water

from rivers

Internalflooding

River w

aterquality

Beaches &

bathing waters

External

flooding

Pollution

incidents torivers

• Our research shows that customers want us to ‘get the basics right’ and deliver our services in a sustainable way

• Improvements in security of supply and drinking water quality ranked very highly in the detailed willingness to pay surveys

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Wessex Water supply area

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• Why do we need a grid?– Standalone sources (21%)– 23.5 Ml/d of low flow reduction (4%)– 43 Ml/d of high nitrate sources (8%)– Growing peak demand

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This couldn’t happen to us?

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Stand alone sources

B R

E L

Bristol

BathChippenham

Salisbury

Bournemouth

Poole

Dorchester

Taunton

Bridgwater

Yeovil

Existing network

Stand alone sources

LEGEND

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Low flows reductions

R. Wylye

R. Avon

-5 Ml/d -6 Ml/d -1.5 Ml/d

-11 Ml/d

-23.5 Ml/d

Low Flow licence reductions

Brixton Deverill Codford

Newton Toney

Clarendon

R. Wylye

R. Avon

-5 Ml/d -6 Ml/d -1.5 Ml/d

-11 Ml/d

-23.5 Ml/d

Low Flow licence reductions

-5 Ml/d -6 Ml/d -1.5 Ml/d

-11 Ml/d

-23.5 Ml/d

Low Flow licence reductions

Brixton Deverill Codford

Newton Toney

Clarendon

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Deteriorating raw water - nitrates

Fonthill Bishop Nitrate Trend

0

2

4

6

8

10

12

14

1985

1986

1987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

2010

Nitr

ate

as m

g/l a

s N

12

At risk nitrate sources

Existing network

Sources at risk of exceeding nitrate limits

LEGEND

B R

E L

Bristol

BathChippenham

Salisbury

Bournemouth

Poole

Dorchester

Taunton

Bridgwater

Yeovil

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Increasing demand

300

350

400

450

500

550

600

1980 1985 1990 1995 2000 2005 2010 2015 2020 2025 2030 2035

Dis

trib

utio

n in

put (

Ml/d

)

Normal year demand forecast Dry year demand forecastPeak week demand forecast Weekly historic demandAnnual average demand Available resources

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Presentation structure

• Development of the concept– Strategic objectives– What do customers want?– Why do we need a grid?– Is it the best solution?– How catchment management fits in

• Design & construction– Team structure– Project objectives & Scope of works– Environmental constraints– Concept development– Programme

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Strategic options

Issue Plan A Holistic solution

Plan BIndividual solutions

Meeting demand and low flows

Grid New water resource developments

Drinking water quality

Grid & catchment management

Additional water treatment plants

Security of supply Grid Local network improvements

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Costs and benefits

Plan A Holistic solution

Plan BIndividual solutions

Net benefits (present value) £m

162 - 52

Cost beneficial? Yes NoOperating cost £m pa 2.0 3.1

Operational carbon emissions C02e thousand tonnes pa

4.4 6.1

Security of supply – number of consumers no longer at risk of supply restrictions

150,000 35,000

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How the grid addresses the key issuesLocal links omitted for clarity

Existing networkProposed pipelinesSources at risk of exceeding nitrate limitsStand alone sourcesLow flow sourceArea of supply demand deficit

LEGEND

B R

E L

Bristol

BathChippenham

Salisbury

Bournemouth

Poole

Dorchester

Taunton

Bridgwater

Yeovil

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How the grid addresses the key issuesLocal links shown

Existing networkProposed pipelinesSources at risk of exceeding nitrate limitsStand alone sourcesLow flow sourceArea of supply demand deficit

LEGEND

B R

E L

Bristol

BathChippenham

Salisbury

Bournemouth

Poole

Dorchester

Taunton

Bridgwater

Yeovil

.MAIN

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The projects will deliver multiple outputs

• Ofwat– Final determination

• Environment Agency – National Environment plan

• Drinking Water Inspectorate – Undertakings

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Key dates - 8 year programme with interim milestones

Activity Date

Project Launch 1 April 2010Blashford WTW DWI undertaking March 2014Nitrate schemes DWI undertakings March 2015Elimination of stand alone sources March 2015Completion of integrated grid allowing low flows licences to be revoked

March 2018Commissioning in 2017

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How catchment management fits in

Fonthill Bishop Nitrate Trend

0

2

4

6

8

10

12

14

1985

1986

1987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

2010

Nitr

ate

as m

g/l a

s N

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Catchment management activity

• Reduce risk whilst grid is implemented• Ensure long term supply of compliant

water & optimise operating costs• Advocacy• Nitrates

– Continue 4 AMP4 sites– 8 further sites that may fail in AMP5

• Pesticides– Friar Waddon

• Farmer has agreed to move pesticide activity to another site

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Presentation structure

• Development of the concept– Strategic objectives– What do customers want?– Why do we need a grid?– Is it the best solution?– How catchment management fits in

• Design & construction– Team structure– Project objectives & Scope of works– Environmental constraints– Concept development– Programme

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Project Team Structure

Wessex Water Services Ltd

Wessex Engineering and Construction Services

Atkins Ltd

Designer

Trant ConstructionCivil & MEICA

Contractor

May GurneyCivil & MEICA

Contractor

Work stream

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Programme Manager& CDMc

TRANT MAY GURNEY ATKINSProject

ManagementTeam

CommercialManagerPlannerDesign

Co-ordinators

GroupCommercial Manager

QuantitySurveyors Design PMs

Environmental ServicesEstates

ICAEstimating

Operations Support Team

Network Experts

Grid Workstream

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Project objectives

• Improve security of supply

• Provision for reduction in abstraction licences

• Provision for deteriorating raw water quality

• Meet future water supply demand

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Concept Development

• Original concept – called GC1• Revised concept – GC2• Updated GC2 November 2012

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Grid Concept 1Local links shown

Blandford

Shaftesbury

Existing networkProposed pipelinesSources at risk of exceeding nitrate limitsStand alone sourcesLow flow source

LEGEND

B R

E L

Bristol

BathChippenham

Salisbury

Bournemouth

Poole

Dorchester

Taunton

Bridgwater

Yeovil

.MAIN

Grid Concept 1

Grid Concept 1As PR09 business plan, new link north from Blashford with alternative route around Salisbury

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Grid Concept 2Local links shown

Blandford

Existing networkProposed pipelinesSources at risk of exceeding nitrate limitsStand alone sourcesLow flow source

LEGEND

B R

E L

Bristol

BathChippenham

Salisbury

Bournemouth

Poole

Dorchester

Taunton

Bridgwater

Yeovil

.MAIN

Grid Concept 2

Grid Concept 2Synergies with other schemes along Stour valley & new link north to Whitesheets SR

Shaftesbury

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B R

E L

Bristol

BathChippenham

Salisbury

Bournemouth

Poole

Dorchester

Taunton

Bridgwater

Yeovil

.SPINE

Grid Concept 2Local links shown + updated routes

Existing networkProposed pipelineSource at risk of exceeding nitrate limitsStand alone sourceLow flow source

LEGEND BlandfordForum

Shaftesbury

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Programme of works

• More than 25 individual projects

• Value ranging from £ 0.5 – 30M

• 150km of new Pipelines

• 30 new / uprated Pumping Stations

• 11 new Service Reservoirs

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Corfe Mullen to Salisbury transfer scheme – 65km

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Environmental constraints

7 AONBs2 National Parks539 Sites of special scientific interest6819 County Wildlife sites4500 Scheduled Monuments41748 Listed Buildings36000+ Records of Protected Species3 World Heritage Sites1 Heritage Coastline

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Environmental Factors

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Environmental Factors

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Typical Pipeline Easement

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Considerate Construction and waste management

• Spoil to be re-used where possible as trench backfill material

• Use excess trench spoil at other sites for service reservoir landscaping etc

• Trenchless technology to be used to cross ;– Rivers and watercourses– Railways– Trunk roads and A roads

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Considerate Construction

• Traffic management plans to reduce impact of construction traffic on the local road systems

• Minimise construction traffic on roads by using pipeline easements instead

• Minimise volume of construction traffic by avoiding double handling, location of compounds etc

• Minimise construction durations through effective planning

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New Infrastructure

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Booster Pumping Stations

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Considerate Construction

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Considerate Construction

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Aerial photo’s (from Wessex Drone)

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Ground photo’s

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Delivery Programme

AMP 5 AMP 6

2010 2011 2012 2013 2014 2015 2016 2017

Options

Outline design

Detailed design

Construction

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Water supply grid website(www.wessexwater.co.uk/grid)

Conclusion

– Wessex Water’s largest and most complex project

– The only Water Industry project spanning two AMPs

– Aligns with 25 year vision

– Delivers customer priorities

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