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Water Resources Management Plan 2014 Cambridge Region Appendix A5 - Water Resource Zone Integrity Assessment

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1 Introduction Defining a Water Resource Zone (WRZ) is a key first step in producing the companies water resources management plan (WRMP). A WRZ is the largest self-contained area for managing supply and demand where the infrastructure joining water resource supplies and demand centres can provide customers within the zone the same level of service, i.e. the available supply can be transferred within the zone to different areas of customer demand.

The definition of a WRZ according to Environment Agency and UKWIR key terms is:

“The largest possible zone in which all resources, including external transfers, can be shared and, hence, the zone in which all customers will experience the same risk of supply failure from a resource shortfall.”1

2 Background In the Company’s previous water resources management plan published in January 2010, the company defined the Company area of supply as a single resource zone. The basis for this was the fully integrated supply and distribution network. The nature of the network, and the supply zones that form the water resources zone has not fundamentally changed for the production of the draft WRMP in 2013, however this technical note has been produced to provide further background on the nature of the WRZ to satisfy the regulators that the definition has been met. The Company engaged in discussions with the Environment Agency at an early stage of the WRMP process, and these have formed the basis of the information included here.

3 CAM Water Resource Zone The single resource zone area, with supply sources, demand centres and transfers indicated is shown in Figure 1. The WRZ comprises 5 distinct supply zones, which are interconnected, and these are each discussed in detail in the next sections. The available supply and customer demands, for each supply zone, not taking account of connectivity between the supply zones within the WRZ are indicated in table 1. These figures are based on annual average dry year figures.

Table 1. Sub zone supply and demand

Supply Zone Supply Ml/d Demand Ml/d Demand Ml/d Surplus/deficit (average) (average) (peak) Ml/d (average) Cambridge 96.6 44.2 55.6 52.4 (31.9) Heydon 7.5 7 9.3 0.5 Croydon 2 1.2 1.7 0.8 Linton 6.4 2.8 4.2 3.6 Bourn 1 7.9 10.9 -6.9 Bluntisham 0 9.4 11.1 -9.4 Madingley 0 4.2 6.3 -4.2 Total 113.5 76.7 99.1 36.8

1 Water Resources Planning Guideline Technical Methods and instructions, June 2012, EA

Water Resources Management Plan Page 2 4 Supply Zones

4.1 Cambridge Zone The Cambridge Supply Zone is the largest zone, in terms of both supply and demand. It also has the largest available surplus, due to the majority of sources supplying into the zone. The integrated network provides supply and storage within the zone, and transfer to the north of the company area of supply and WRZ, where there are few, or limited supply sources.

Under normal operations the demand in the Bourn, Bluntisham and Madingley zones is met by the transfer of supply from the Cambridge zone, with the exception of an available 1Ml/d from Kingston in the Bourn zone. This amounts to 20.5Ml/d of demand under average conditions from the surplus within the Cambridge zone normally being transferred. The remaining surplus in the Cambridge zone is 31.9Ml/d when this normal transfer is taken into account.

Additional transfers can be made from the zone as follows:

• Up to 5Ml/d, constrained by available infrastructure, can be transferred into the Heydon zone reservoirs. • 2.4Ml/d (100m³/hr) of surplus can be transferred into the Linton zone via the Fleam Dyke 12” booster, constrained by existing infrastructure

4.2 Bourn, Bluntisham and Madingley Zones As discussed in 4.1 above, these zones to the northern area of the WRZ are supplied by transfer of supply from Cambridge Supply Zone. There is therefore no requirement to transfer from these supply zones to any other zone.

4.3 Heydon Zone Under normal operation the zone is supplied by Heydon, Great Chishill, Morden Grange and Fowlmere sources. The surplus within the zone remains through the planning period until 2040, as there is no significant planned development over the period with the supply zone demand centres.

The supply zone is highly flexible in terms of transfer options and connectivity, with a number of options to transfer resource into and out of the zone as described below:

• The full output from Duxford Grange (3.6Ml/d) can be diverted from the Cambridge Supply zone directly into the Heydon zone by operation of a control valve, or via boosters. • Surplus from the Cambridge supply zone can be diverted from the Melbourn main into Heydon Storage reservoirs by operation of a manual valve and is dependent on Fowlmere relift pumps. This is in the order of 5Ml/d (210m³/hr) constrained by the pumps.

Water Resources Management Plan Page 3 • Transfer from the Heydon zone into the Cambridge zone, via the Fowlmere to Cambridge booster is possible, although this is an unlikely scenario as surplus is higher in the Cambridge zone. • A transfer from the Heydon Zone into the Croydon zone is available, the capacity of which is 1.6 Ml/d

4.4 Linton Zone The supply zone of Linton is self-sufficient under normal operating conditions. Supplies in this zone may be subject to sustainability reductions under the Restoration of Sustainable Abstraction programme over the WRMP planning period, in the order of 1.5Ml/d, however a surplus would still be expected in the zone. Transfer between the Linton zone and Cambridge zone of up to 2.4Ml/d is possible using the Fleam Dyke 12” booster or by valve operations. The infrastructure capability of the transfer into the zone has been sized to compensate for the equivalent loss of the largest source within the zone.

4.5 Croydon Zone Croydon is a highly simplified supply zone, with a single source into storage and then into supply, hence the transfer of supply out of the zone is not a consideration. A transfer from the Heydon zone into the Croydon zone allows for the transfer of up to 1.6Ml/d. This effectively allows surplus from the Cambridge Zone to be passed through Heydon and into Croydon, if required.

5 Impact of Planned Development The majority of known planned development is within the Cambridge supply zone, notably the North West Cambridge, Northstowe and NIAB developments, where the majority of the WRZ resource surplus is available. Therefore the additional demand from this growth can easily be met within the overall WRZ. Where required, reinforcement work to the network in the Cambridge supply zone will be carried out for these developments, to ensure that existing customers are not affected by these developments.

There are no known significant planned developments or major growth in any other supply zones at this time. Should any occur however, then any necessary network improvements and reinforcement would be carried out as required to ensure that customers level of service remains consistent. This will ensure surplus resource within the WRZ can be effectively transferred where needed.

6 Bulk Imports and Exports The Company operates a single Bulk Export, to Veolia at Hadstock, from the Linton Supply zone. This is a small export supplying properties directly from the WRZ.

Water Resources Management Plan Page 4 Two Bulk imports exist, one at Earith Bridge in the East from Anglian Water, and one at Odsey in the South from Veolia. The Earith Bridge import directly supplies 8 Cambridge Water customers in the WRZ. The Odsey Bulk import directly supplies 35 Cambridge Water customers in the WRZ, and is a separate supply zone.

These imports and exports are indicated on the WRZ schematic, and the size of these excludes them from the WRZ definition for transfer of surplus, as they are subject to the de- minimus rule of the definition.

7 Conclusion Historical factors have led to the company WRZ being made up from a number of sub supply zones for supply management, however where these have supply resources available, there is a high level of connectivity to allow for transfer of resources between all of the supply zones, hence the area of supply meets the definition of a WRZ.

The largest supply zone, Cambridge contains the majority of the sources of supply, and also has the largest surplus available. This zone also supplies the zones without supply sources available.

In conclusion the area of supply boundary provides the most appropriate boundary for the definition of a WRZ for Cambridge Water, being an appropriate geographical boundary within which there exists a high level of infrastructure connectivity, and ability to transfer resource within the zone. This integrated supply network ensures that all customers within the company area of supply, and hence WRZ receive the same level of risk to public supply, subject to the de-minimus rules of the definition.

Water Resources Management Plan Page 5 Figure 1 – WRZ Schematic

RAMSEY WISTOW RESERVOIR TOWER WISTOW ZONE RAMSEY ZONE TOWER RESERVOIR

1.2 ml/d 0.6 ml/d 1.6 ml/d 0.8 ml/d

BURY WARBOYS BURY BOOSTER TOWER BOOSTER ZONE EUSTON WARBOYS PUMPING STATION TOWER 0.5 ml/d 0.1 ml/d 0.7 ml/d 0.1 ml/d ZONE BRETTENHAM PUMPING STATION 8.0 ml/d

WOODHURST BLUNTISHAM WOODHURST BOOSTER 11.3 ml/d TOWER BOOSTER ZONE BLUNTISHAM TOWER 6.9 ml/d 0.1 ml/d 7.7 ml/d 0.2 ml/d ZONE 8 PROPERTIES

EARITH BRIDGE BULK IMPORT5.3m³/d BOURN BLUNTISHAM MADINGLEY BLUNTISHAM BOOSTER

ST. IVES ST. IVES ST. IVES ST. IVES EUSTON BOOSTER RESERVOIR BOOSTER RESERVOIR RELIFT ZONE ZONE WESTLEY PUMPING STATION 0.1 ml/d 1.5 ml/d BLUNTISHAM 0.1 ml/d 2.1 ml/d RESERVOIR DULLINGHAM PUMPING STATION 11.4 ml/d WESTON COLVILLE PUMPING STATION

MADINGLEY OVER 3.6 ml/d 2.8 ml/d MADINGLEY RESERVOIR OVER TOWER WILBRAHAM CHERRY HINTON RESERVOIR ZONE TOWER ZONE PUMPING STATION MADINGLEY MADINGLEY RESERVOIR TOWER TOWER 5.7 ml/d 3.5 ml/d .7 ml/d ZONE 5.2 ml/d 1.1 ml/d BOURN CASTLE HILL 0.9 ml/d RESERVOIR 1.2 ml/d 0.3 ml/d BOOSTER ZONE 0.5 ml/d COTON A ZONE FLEAM DYKE 36" BOOSTER PUMPING STATION

1.12 ml/d 12.4 ml/d 1.5 ml/d BOURN BOURN BOURN BOURN TOWER TOWER BOOSTER ZONE RESERVOIR GRANTCHESTER CAMBRIDGE ROAD COTON B BOOSTER 1.6 ml/d BOOSTER CASTLE HILL FLEAM DYKE 12" 2.6 ml/d BOOSTER PUMPING STATION

3.2 ml/d

42.8 ml/d 53.7 ml/d CAMBOURNE CAMBRIDGE BOOSTER EVERSDEN ZONE BOOSTER KINGSTON FULBOURN PUMPING STN PUMPING STATION 1.0 ml/d WANDLEBURY BOOSTER 1.5 ml/d ZONE EVERSDEN EVERSDEN 1.4 ml/d CAMBOURNE RESERVOIR 1.9 ml/d RESERVOIR BOOSTER 2.1 ml/d ZONE MELBOURN 0.0 ml/d FLEAM DYKE 12" 2.5 ml/d ZONE PUMPING STATION 0.0 ml/d BOOSTER

7.9 ml/d GENOME WANDLEBURY LONGSTOWE BOOSTER BOOSTER LONGSTOWE 0.1 ml/d TOWER 0.1 ml/d LOWERFIELD ZONE LINTON-CAMBRIDGE TOWER ZONE PUMPING STATION VALVE (N/C) LINTON

0.3 ml/d 0.4 ml/d 3.4 ml/d

CHISHILL LOWERFIELD BALSHAM BALSHAM BALSHAM GENOME PUMPING STATION BOOSTER BOOSTER TOWER TOWER BOOSTER ZONE HATLEY 0.1 ml/d 1.2 ml/d 0.2 ml/d 0.6 ml/d 1.0 ml/d FOWLMERE TO 9.1 ml/d CAMBRIDGE SV 8040 (N/C) BOOSTER BABRAHAM HEYDON PUMPING STATION PUMPING STATION CROYDON SAWSTON MILL HEYDON RELIFT BOOSTER 1.5 ml/d RESERVOIR HEYDON SAWSTON 1.1 ml/d PUMPING STATION FOWLMERE LINTON RIVEY B RELIFT PUMPING STATION PUMPING STATION

CROYDON CROYDON 1.1 ml/d RESERVOIR 1.9 ml/d 2.2 ml/d RESERVOIR 1.5 ml/d ZONE

FOWLMERE PUMPING 3.6 ml/d 4.6 ml/d STATION HORSEHEATH HINXTON GRANGE PUMPING STATION HEYDON DUXFORD AIRFIELD RELIFT 6.8 ml/d RESERVOIR PUMPING STATION 9.0 ml/d ZONE LINTON HEYDON TO CROYDON RESERVOIR 0.0 ml/d EMERGENCY TRANSFER HEYDON DUXFORD GRANGE TO HEYDON BOOSTER VALVE (N/C) RIVEY SHUDY CAMPS BOOSTER BOOSTER

DUXFORD GRANGE RIVEY SHUDY CAMPS TOWER TOWER MORDEN GRANGE RELIFT 1.0 ml/d RELIFT 2.0 ml/d ABINGTON PARK PUMPING STATION CROYDON FOWLMERE HADSTOCK BULK EXPORT BOOSTER RIVEY PUMPING STATION 5.8 ml/d SHUDY CAMPS BOOSTER TOWER ZONE ZONE HINXTON GRANGE 0.2 ml/d 3.4 ml/d 1.7 ml/d CROYDON 0.3 ml/d PUMPING STATION 2.4 ml/d 0.2 ml/d 0.3 ml/d 0.3 ml/d 0.5 ml/d 1.6 ml/d HEYDON DUXFORD GRANGE LINTON BOOSTER PUMPING STATION RESERVOIR ODSEY BULK IMPORT ZONE ZONE MORDEN GRANGE PUMPING STATION CAMBRIDGE TO HEYDON ZONE PSV 35 PROPERTIES 41.2m³/d

PROJECT TITLE NOTES:- BOREHOLE SOURCE NETWORK LINK INDICATING 0.0 ml/d NORMAL FLOW DIRECTION

BOOSTER/RELIFT PUMP NETWORK LINK INDICATING CONTROLLING CAMBRIDGE WATER COMPANY VALVE (NORMALLY CLOSED) WATER RESOURCE ZONE AND SUPPLY ZONE SCHEMATIC

RESERVIOR/TOWER NETWORK LINK NOT USED UNDER NORMAL OPERATION

0.0 ml/d SUPPLY SUB ZONE BOUNDARY 0.0 ml/d CUSTOMER DEMAND STATUS DRAWN CHECKED DATE SCALE DRAWING No. REV PRELIMINARY JBr/SJE DC 06/08/12 N.T.S @ A1 DRAWN CHECKED DATE DESCRIPTION REV A

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