Ely Ouse to Essex Transfer Scheme

Essex & Suffolk Water: Ely Ouse to Essex Transfer Scheme

25 October 2011

Will Robinson Water Resources Manager

nwlpp Presentation Overview

• ESW Water Resources • Ely Ouse Essex Transfer Scheme • The Abberton Scheme

nwlpp ESW Water Resources

nwlpp ESW Treated Water Supply Areas

Population: 1.82m (1.5 million in Essex) Water supplied: 458 Ml/d (Average) Average Annual Rainfall: Hanningfield: 575mm Barsham: 630mm nwlpp Essex Resource Zone and Associated Infrastructure

nwlpp Essex Raw Water Sources

Bulk Supply Import from Groundwater 3% TWU to Chigwell 20%

Essex Rivers 47% Ely Ouse to Essex Transfer Scheme 30% (in dry years)

nwlpp Ely Ouse Essex Transfer Scheme: History

• 1964: Ministry of Housing and Local Government Study highlighted water supply issues in Essex • 1968: Ely Ouse Essex Water Act enabled construction works • 1971/72: First Transfers to Essex

nwlpp Denver Existing Ely Ouse Essex Blackdyke Tunnel Transfer Scheme Kennett PS

Kirtling Green Outfall

Wixoe PS

Gt Sampford O/F

Abberton Reservoir

Langford

nwlpp Hanningfield Reservoir Denver Complex

The Denver complex

The Wash

Denver Sluice

Ouse Washes Flood Relief Channel

Diversion Sluice To Essex

Cut Off Channel nwlpp Ely Ouse Essex Transfer Scheme

• 18 month quantity: 79,555 Ml • Daily quantity: 455 Ml/d • Monthly HOF configuration: – March to August: 114Ml/d – September to February: 316Ml/d

• Transfers to Essex (2008 Baseline): – Average 18 month: 15,800 Ml – Maximum 18 month: 58,000 Ml Transfers generally made in dry years with often no transfers in average or wet years nwlpp

Scheme Operation • Scheme owned and operated by the Environment Agency • Operated in accordance with the operators manual • Quarterly Operator Group Meetings – EA and Essex & Suffolk Water – Review of available resources – Transfer Forecasts • Control Curves informs operational decision making – Ensure reservoir storage is sufficient to reliably meet demand

nwlpp Reservoir Control Curves

nwlpp Aquator®

• Maximises water resource yield within licence and infrastructure constraints • Daily time-step • Naturalised flow sequence DO • Denaturalised with abstraction Maximum yield possible and discharge profiles Scenario Analysis Run with a specified demand to assess behaviour of system

nwlpp nwlpp Refill Reliability Approach

Refill Reliability Matrix 2012/13 - Combined Reservoir Storage - Abberton maximum allowed level applied

Volume at bottom Zone Band Storage Ml % May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr Zone Ml 50995 100% 50995 - 48700 A 48700 95% 91.10% 91.10% 95.80% 97.40% 99.00% 99.00% 99.00% 99.00% 99.00% 99.00% 99.00% 99.00% 48700 - 46405 B 46405 91% 91.10% 89.50% 91.10% 97.40% 99.00% 99.00% 99.00% 99.00% 99.00% 99.00% 99.00% 97.40% 46405 - 44110 C 44110 86% 89.50% 89.50% 91.10% 92.70% 99.00% 99.00% 99.00% 99.00% 99.00% 99.00% 99.00% 92.70% 44110 - 41815 D 41815 82% 89.50% 89.50% 91.10% 92.70% 97.40% 99.00% 99.00% 99.00% 97.40% 97.40% 95.80% 69.00% 41815 - 39520 E 39520 77% 89.50% 87.90% 87.90% 87.90% 94.30% 99.00% 99.00% 99.00% 97.40% 97.40% 92.70% 42.10% 39520 - 37225 F 37225 73% 87.90% 87.90% 86.40% 87.90% 92.70% 97.40% 99.00% 99.00% 97.40% 97.40% 91.10% 37225 - 34930 G 34930 68% 87.90% 87.90% 84.80% 86.40% 89.50% 95.80% 99.00% 97.40% 97.40% 94.30% 81.60% 34930 - 32635 H 32635 64% 86.40% 87.90% 84.80% 86.40% 89.50% 92.70% 97.40% 95.80% 94.30% 91.10% 67.40% 32635 - 30340 I 30340 59% 86.40% 84.80% 84.80% 84.80% 89.50% 91.10% 95.80% 94.30% 92.70% 87.90% 51.60% 30340 - 28045 J 28045 55% 86.40% 83.20% 84.80% 84.80% 86.40% 89.50% 91.10% 92.70% 92.70% 86.40% 7.30% 28045 - 25750 K 25750 50% 81.60% 78.50% 81.60% 84.80% 86.40% 89.50% 91.10% 91.10% 87.90% 75.30% 25750 - 23455 L 23455 46% 80.00% 78.50% 80.00% 84.80% 84.80% 89.50% 89.50% 91.10% 86.40% 64.20% 23455 - 21160 M 21160 41% 78.50% 78.50% 78.50% 83.20% 84.80% 86.40% 89.50% 86.40% 80.00% 18.40% 21160 - 18865 N 18865 37% 78.50% 75.30% 76.90% 83.20% 81.60% 84.80% 86.40% 86.40% 51.60% 1.00% 18865 - 16570 O 16570 32% 76.90% 72.10% 72.10% 72.10% 78.50% 83.20% 84.80% 80.00% 7.30% 16570 - 14275 P 14275 28%

14275 - 11980 Q 11980 23%

11980 - 9685 R 9685 19%

9685 - 7390 S 7390 14%

– Looks at what happened in each month since 1934 – Model provides a probability of achieving refill by end of April for any given starting month and storage state – Purpose of approach is to ensure resrvoirs are full by begining of following drawdown period nwlpp Water Resources Planning

nwlpp Water Resource Management Plan

• Water Resources Management Plan Regulations 2007 • Plan produced every 5 years – Current Plan 2010 to 2015 • Sets out how supply will be met over the next 25 years • Process • Forecast Demand (Distribution Input) • Assess water Available for Use (WAFU) • Establish whether there is a supply surplus / deficit • Identify Demand Reduction / Supply Schemes

nwlpp Dry Year Supply Demand Balance

Baseline Water Available For Use Essex Resource Zone: Final Supply Demand Balance v Distribution Input 500

480

460

440

420

Ml/d 400 Increasing Supply Deficit

380

360

340

320

Distribution Input nwlpp Water Available for Use (WAFU) (Baseline) Water Available For Use - Baseline Water Resource Management Plan

Twin Track Approach • Reduce Demand – Leakage Reduction: One of the lowest in the UK – Metering: 49% in Essex – Promotion of Water Efficiency • Reducing demand by 1 litre/property/day • New Supplies – Options Appraisal (Inc. Environmental Impact Assessment) – Least Cost Least Environmental Impact Solution • Abberton Scheme nwlpp Essex Resource Zone: Final Supply Demand Balance

500

480 Only small surplus 460

440

420 Abberton Raising and

Ml/d Transfer 400 Enhancement 380

Denver Licence 360 Variation

340

320

2006/07 2007/08 2008/09 2009/10 2010/11 2011/12 2012/13 2013/14 2014/15 2015/16 2016/17 2017/18 2018/19 2019/20 2020/21 2021/22 2022/23 2023/24 2024/25 2025/26 2026/27 2027/28 2028/29 2029/30 2030/31 2031/32 2032/33 2033/34 2034/35 Year Distribution Input nwlpp Baseline Water Available For Use Water Available For Use - BaselineFinal Plan WaterDistribution Available Input For inc. UseVariable Target Headroom - Final Plan The Abberton Scheme

nwlpp Denver Licence Variation

Denver

The Abberton Scheme

Transfer Northern Pipeline Enhancement

Wixoe PS

Wormingford Intake & Southern Pipeline

Abberton Reservoir Enlargement

Langford Intakes

nwlpp Hanningfield Reservoir Denver Licence Variation

• 18 month quantity increased from 79,555Ml to 100,000Ml • Maximum daily quantity to remain unchanged at 455 Ml/d • Monthly HOF configuration to be changed:

Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Pre-variation (Ml/d) 318 318 114 114 114 114 114 114 318 318 318 318 Proposed Variation (Ml/d) 318 318 318 318 114 114 114 114 318 114 114 114

This HOF configuration allows for higher transfers when river flows are higher

nwlpp Current & Future Transfers to Essex

2014 2014 + 2027 2027 + Baseline Abberton Baseline Abberton Scheme Scheme

Average 18 month Transfer 18.6 17.7 21.6 18.6 (Mm3)

nwlpp Denver

Transfer Enhancement Northern Pipeline

Wixoe PS Southern Pipeline

Abberton Reservoir

Langford Intakes nwlpp Hanningfield Reservoir Main Dam being raised

Wormingford New Temporary pipeline Inlet Pumping to be built Station

Causeway to be raised

nwlpp New Temporary Pumping Station

Concrete Edge Removal

nwlpp Edge Re- profiling

nwlpp nwlpp Conclusions of EIA

• The Abberton Scheme has been assessed as having no significant effect upon water, biodiversity, and recreation & socio-economics

• The Habitats Regulations Assessments of impacts upon the European Sites identified no adverse effect upon interest features and were approved by NE.

• The Abberton Scheme has been designed as far as possible, to prevent, reduce or off-set potential adverse environmental effects and, where appropriate, to deliver environmental enhancements.

nwlpp Abberton Scheme Benefits

• Forecast customer demand will be met over the next 25 years • The enlarged Abberton Reservoir and Wormingford to Abberton pipeline will enable the use of higher intrinsic flows in the River Stour than is currently possible. – Less water will be taken from Denver in most years • Reservoir ecology enhancements – New, gently sloping, natural edge – Creation of 6ha wetlands – Creation of reedbed areas

nwlpp Timeline: Abberton Scheme

• 1993: Studies begin • 1999: Included in Water Resources Plan • 2004: Included in Water Resources Plan • 2007: Environment Statement finalised • 2009: Justification of Need demonstrated in Company’s Water Resources Management Plan All planning consents secured • 2010: DEFRA Accept Justification of Need for the Full Abberton Scheme Funding for the full Abberton Scheme secured via Ofwat’s Period Review process (PR09) Start of Reservoir Construction • 2011: Denver Licence Variation granted • 2013: Dam raising Contractors leave site

nwlpp • 2014/15: Filling enlarged reservoir

Questions?

nwlpp