Presentation by

South West WaterExperiences of Pumped Storage

Jo RobinsonResources AnalystSouth West Water

Overview

• Pumped Storage Explanation • SWW Pumped Storage Schemes• Developing a Scheme• Pumped Storage Operation• Conclusions

Pumped Storage

• Making use of higher winter river flows to aid reservoir refill

• Maximising effective catchment area• Reservoir no longer just dependant on natural

refill• Useful for multi-season reservoirs which have

potential to be more susceptible to successive dry winters

Pumped Storage

• Can be operated as long as flow is available (subject to licences)

• Enables water to be taken from reservoir at a greater rate during summer knowing that it can be topped up in winter if required

• Reduces risk of low reservoir levels the following summer which could lead to customer restrictions, drought orders/permits and poor reservoir water quality

The effect of pumped storage on a 24 month drought

pum

ping

perm

itted

pum

ping

perm

itted

pum

ping

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itted

J F M A M J J A S O N D J F M A M J J A S O N D1975 1976

0%

100%

ReservoirStorage

Storage increase due to pumping

But…

• Schemes are expensive – high energy consumption

• Schemes are subject to environmental constraints– potential impact on flows required to help

fish migration– potential loss of natural variation in flows– potential impact to water quality in reservoir

SWW Pumped Storage Schemes

Pumped Storage Scheme

Developing a PS Scheme

Case Study:WimbleballReservoir

Wimbleball Supply/Demand Balance

New Water Resource Solutions

• Increasing groundwater supplies

• Axe Valley Reservoir

• Wimbleball Pumped Storage Scheme

Wimbleball Pumped Storage Scheme

Pumps water from Exebridge back to the reservoir

We no longer have to rely on natural inflow alone

Allers WTW

Maundown WTW(Wessex Water)

Pynes WTW

Wimbleball Reservoir

TIVERTON

EXETER

Exebridge

Licence Application

Need to demonstrate that the whole water strategyhas been considered by showing:• Below economic level of leakage• Potential infrastructure enhancements have been

carried out• Water conservation is being promoted• That having done all this there is still a need to

take water from the environment via pumped storage

Licence Application

Scheme Construction

Main Elements of the Scheme

• Weir• Intake screens• Pumping station• Water main• Tunnel • Outfall structure

Weir is 21m wide and used for:• raising the water level to enable intake to operate• measuring the flow to ensure licence compliance

Exebridge Weir

Intake Screens

9m long coarse trash screen with 6mm slots to screen large debris

• 8 Johnson passive screens with 3mm slots

• Screens are “fish friendly”but block easily

Johnson Passive Screens

Site of ExebridgePumping Station

Exebridge Pumping Station

Tunnel

Wimbleball Reservoir Outfall

Environmental Considerations

Fish Movement Studies

Environmental sensitivity of pipeline routes

Pumped Storage Operation

CollifordPS Outfall Structure

Deciding when to Pump

• Period of licence eg Wimbleball Nov – Mar• Licence availability

– Daily licence– Annual licence (not always x365 daily)– Licence may be used in conjunction with

abstractions for public water supply

Reservoir Pumping Zones

DCP Zone ADCP Zone BDCP Zone CDCP Zone DConsider Winter Pumping

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2500

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20000

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1/06

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6/06

01/0

7/06

01/0

8/06

01/0

9/06

01/1

0/06

01/1

1/06

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2/06

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l)

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Wimbleball Pumping Zones

Reservoir Storage Projections

0

2500

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20000

01/0

1/06

01/0

2/06

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3/06

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01/0

6/06

01/0

7/06

01/0

8/06

01/0

9/06

01/1

0/06

01/1

1/06

01/1

2/06

01/0

1/07

01/0

2/07

01/0

3/07

01/0

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5/07

Rem

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196 2 19 63 1964 1965 1966 1967 1968 19 69 1970 1971 1972 1973 19741975 19 76 1977 1978 1979 1980 1981 19 82 1983 1984 1985 1986 1987198 8 19 89 1990 1991 1992 1993 1994 19 95 1996 1997 1998 1999 2000

Abstract as required

Consider implementationof bans on non-esssential

use of water

Consider implementation of hosepipe bans & drought

Initiate regular contacts with the EA and increase publicity

Wimbleball Indicative Projected Storage 06/07

A series of possible outcomes which can provide an indication of the probability of various states of storage occurring in the future.

Autumn leaf clogging reduces volume pumped

Operational Issues

Riparian and fisheries interests

Intake Protection

• Water quality monitoring instruments and triggers to avoid abstraction of poor quality water

• Regular maintenance and calibration

• 24 hr site manning• Awareness of pipeline

delivery times • Rapid notification and

shutdown in the event of a pollution incident

Deciding when to Stop Pumping

• Once a PS scheme is shut down it is difficult to restart

• Important to have a controlled shut down• Pumping zones – has target storage been

reached? • Weather forecasts• Have licence constraints been reached?

0

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22000

Date

Rem

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10%

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100%

Rem

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DCP Zone ADCP Zone BDCP Zone CDCP Zone DConsider Winter Pumping2006 Net Storage

Net Capacity 21320 Ml

Consider Winter Pumping

Storage without pumping

Actual storage with pumping

Use of Wimbleball Pumped Storage in 2005/06

Conclusions

• Secures reliable supplies– reduces the risk of hose pipe bans– reduces the risk of drought orders affecting the

environment

• More effective use of an existing asset• Requires careful operational management

– to minimise pumping costs– to avoid adverse environmental effects– can require constructive dialogue with

stakeholders

Colliford Reservoir

Questions