Water NATURE'S PRECIOUS RESOURCE An Environmentally Sustainable Water Resources Development Strategy for England and Wales SUPPLEMENTARY REPORT Q & C t [S3 NRA National Rivers Authority 'OTHER' OPTIONS Supplementary Report No 4 May 1994 % ® Sir William Halcrow & Partners Ltd 1994 Sir William Halcrow & Partners Ltd has prepared this report in accordance with the instructions of the National Rivers Authority for their sole and specific use. Any other persons who use any information contained herein do so at their own risk. Sir William Halcrow & Partners Ltd Burderop Park Swindon Wiltshire SN4 OQD Tel 0793 812479 Telex 44 84 4 Halwil G Fax 07 93 812089 National Rivers Authority Water Resources Development Strategy ’Other’ Options Supplementary Report No 4 May 1994 Contents Amendment Record This report has been issued and amended as follows: Issue Revision Description Date Signed 1 1 31.5.94 NATIONAL RIVERS AUTHORITY WATER RESOURCES DEVELOPMENT STRATEGY SUPPLEMENTARY REPORT No 4 ‘OTHER’ OPTIONS Contents List Page No 1 INTRODUCTION AND SUMMARY 1-1 1.1 Introduction 1-1 1.2 Summary 1-3 2 BARRAGES 2-1 2.1 General 2-1 2.2 Water Resource Tidal Barrages 2-2 2.3 The Wash Barrage 2-3 2.4 Morecambe Bay Barrage 2-11 2.5 Comparison of Schemes 2-15 3 GROUNDWATER RECHARGE 3-1 3.1 General 3-1 3.3 Groundwater Recharge in the NRA Regions 3-9 3.4 Environmental Considerations 3-12 3.5 Costs 3-13 EFFLUENT REUSE 4-1 4.1 Definitions 4-1 4.2 Reuse for Potable Water Supply 4-1 4.3 Reuse for Other Purposes 4-5 4.4 Treatment Technology 4-7 4.5 Environmental Considerations 4-10 4.6 Costs 4-11 5 DESALINATION _ 5-1 5.1 General 5-1 5.2 Desalination Processes 5-2 5.3 Operational Considerations 5-7 5.4 Existing UK Plants 5-8 5.5 Power Sources 5-9 5.6 Water Sources 5-10 5.7 Potential Desalination Sites 5-10 5.8 Environmental Considerations 5-11 5.9 Costs 5-14 6 UNDERSEA PIPELINES 6-1 6.1 General 6-1 6.2 Potential Pipeline Routes and Resources 6-1 6.3 Pipeline Engineering 6-2 6.4 Pipeline Operation and Maintenance 6-4 6.5 Environmental Considerations 6-5 6.6 Costs 6-7 7 TANKERS AND WATER SACS 7-1 7.1 General 7-1 7.2 Tankers 7-1 7.3 Water sacs 7-5 7.4 Operational Considerations - Tankers and Water Sacs 7-8 8 CRAIG GOCH ENLARGEMENT 8-1 8.1 Background 8-1 8.2 Scope of Scheme Options 8-1 8.3 Development Options and Assumptions 8-3 8.4 Environmental Considerations 8-6 8.5 Costs 8-11 9 VYRNWY REDEPLOYMENT 9-1 9.1 Background 9-1 9.2 Description of Existing Vyrnwy Works 9-1 9.3 Proposed Redeployment 9-3 9.4 Regulation Options 9-4 9.5 Environmental Considerations 9-6 9.6 Costs 9-6 10 KIELDER TRANSFER SCHEME 10-1 10.1 Background 10-1 10.2 Existing Kielder Scheme 10-1 10.3 Hydrological Considerations 10-2 10.4 Proposed Transfer Works 10-4 10.5 Environmental Considerations 10-7 10.6 Costs 10-12 11 NATIONAL WATER GRID 11-1 11.1 General 11-1 11.2 Demands 11-1 11.3 Resources 11-3 11.4 Grid Structure 11-4 11.5 Construction Programme 11-5 11.6 Grid Operation 11-6 11.7 Environmental Considerations 11-7 11.8 Costs 11-7 12 CONSIDERATION OF OPTIONS, CONCLUSIONS AND RECOMMENDATIONS 12-1 12.1 General 12-1 12.2 Barrages 12-1 12.3 Groundwater Recharge 12-2 12.4 Effluent Reuse 12-2 12.5 Desalination 12-3 12.6 Undersea Pipelines 12-3 12.7 Tankers and Water Sacs 12-4 12.8 Craig Goch Enlargement 12-4 12.9 Vyrnwy Redeployment 12-5 12.10 Kielder Transfer 12-6 12.11 National Water Grid 12-6 1 INTRODUCTION AND SUMMARY 1.1 Introduction 1.1.1 Background This report is the fourth in a series of nine supplementary reports which provide supporting information for the National Rivers Authority Water Resources Development Strategy document: "An Environmentally Sustainable Water Resources Development Strategy for England and Wales". The other reports in the series are as follows: 1 Methodology and Assumptions for Demand Scenarios; 2 Review of Public Water Supply Yields; 3 Marginal Demands; 5 Hydrological Modelling; 6 Resource Scheme Costings; 7 RESPLAN Modelling; 8 Comparative Environmental Appraisal of Strategic Options; 9 National Strategy Overview. The NRA is committed to publishing a water resources strategy for England and Wales to meet demands up to the year 2021. The strategy is likely to have several components, including elements of demand management, local source development and inter-regional transfer. A number of studies are already under way; these address a variety of major strategic resource development and water transfer schemes in terms of practicability, cost and environmental impact. There are, however, a number of ’other’ options which, due to their lesser strategic importance, expense or previous studies, have not attracted large scale investigation at this time. Sir William Halcrow and Partners Ltd (Halcrow), in its role as Project Manager for the NRA’s Water Resources Strategy, was asked to review, at a broadbrush level, a number of these ’other’ options to identify those which could form part of the national resource strategy and, therefore, warrant further, more detailed study. Those options not considered appropriate for the national strategy, however, might still be important at a local level. The following ten ’other’ options have been investigated: • Barrages • Groundwater Recharge • Effluent Reuse • Desalination Undersea Pipelines • - Tankers and Water Sacs • Craig Goch Reservoir Enlargement 1-1 • Vyrnwy Redeployment • Kielder Transfer • National Water Grid As can be seen, the above options include specific sources, such as Craig Goch and Vyrnwy, general resource development opportunities such as effluent reuse and groundwater recharge, and transfer options such as the national water grid and undersea pipelines. 1.1.2 Layout The report has been divided into ten sections, one section for each option. The structure of each section varies slightly with the nature of the subject; however, in general each section addresses: • the principles and general advantages and disadvantages of the option under consideration: • the engineering feasibility of the option; • the potential yield of the option; • environmental considerations; and • estimated capital and operating costs. No estimates, however, have been given for the potential yield of the transfer options - the transfer schemes themselves not providing a resource - or those options such as desalination and effluent reuse where yield is not a limiting factor. Much more detailed investigations, including hydrological modelling, would be required to establish the yields associated with the transfer options. The degree to which the environmental implications of the options have been investigated is dependent upon the level of available information and the specificity of the option proposals. In the case of the transfer option by tanker or water-sac there are thought to be no significant environmental implications resulting from the transportation of water which do not already occur as a result of existing tanker and port activities. The environmental considerations of this option have not, therefore, been addressed as a separate issue. Wherever possible, option costs have been based upon either updated scheme costs or previous estimates. In cases where no information was available a component based estimate has been derived using updated costs formulae from TR61 * Cost Information for Water Supply and Sewage Disposal. This document was developed in the mid 1970's and contains cost functions for various different water scheme components. Details of the method are given in the NRA’s Water Resource Planning Report Volume 2. The costs given in the report include capital and annual operating costs. Unit yield costs have been calculated based upon the capital costs and thirty years amortised operating costs discounted at a rate of 8% per 1-2 annum. The unit costs do not include for equipment replacement and assume the option yields to be annual averages. Discussion of the options’ appropriateness for inclusion within the national resources strategy is contained in Section 12. The advantages and disadvantages of each option are summarised and, if warranted, recommendations for further work are made. 1.2 Summary Sir William Halcrow and Partners Ltd (Halcrow), in its role as Project Manager for the NRA’s Water Resources Strategy, was asked to review a number of water resource and water transfer options which could form part of the national strategy, but which are not specifically the subject of detailed investigation within the range of studies being carried out under the national strategy study. This report sets out the findings of the review, the principal objective of which was to determine whether any of these 'other' options warrant further study with regard to possible inclusion in the national strategy. Barrages, desalination and Craig Goch have been the subject of extensive previous studies, whilst others such as the Kielder transfer, the national water grid, undersea pipelines and tankers and water sacs have not been investigated in detail. Groundwater recharge and effluent reuse have been the subject of local investigations; however, their importance as strategic options has not been addressed in the past. The resource implications of redeploying Vyrnwy are at present being studied by teams from North West Water, North West NRA and Severn Trent NRA; this report considers the engineering feasibility and environmental implications of converting Vyrnwy from direct supply to river regulation. The options have been considered, for their general advantages and disadvantages, engineering feasibility, resource yield, environmental implications and costs.