HERTFORDSHIRE WATER STUDY 2017 HERTFORDSHIRE COUNTY COUNCIL Infrastructure & Resources, Sub-Catchment Solutions (2021 – 2051)
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HERTFORDSHIRE WATER STUDY 2017 HERTFORDSHIRE COUNTY COUNCIL Infrastructure & Resources, Sub-catchment Solutions (2021 – 2051) MARCH 2017 VERSION CONTROL Version Date Author(s) Checker Approver Comments D1 18/11/2016 Simon Ainley / Aimee Hart Neil McClung R Gunasekara Draft Issue D2 15/03/2017 Simon Ainley / Aimee Hart Neil McClung R Gunasekara 1st Issue 7.3 Identification of Water Infrastructure Options ..................... 38 CONTENTS 8 DISTRICT SUMMARIES .......................................... 42 1 EXECUTIVE SUMMARY ............................................ 4 8.1 Chiltern ..................................................................................... 43 2 STUDY PARTNERSHIP ............................................. 5 8.2 Dacorum ................................................................................... 48 8.3 East Hertfordshire ................................................................... 53 3 WATER VISION FOR HERTFORDSHIRE ................. 1 8.4 Hertsmere ................................................................................. 58 3.1 Principles of the Vision ............................................................. 1 8.5 North Hertfordshire ................................................................. 63 4 BACKGROUND .......................................................... 1 8.6 St Albans .................................................................................. 68 4.1 Overview ..................................................................................... 1 8.7 Stevenage................................................................................. 73 4.2 Urban Growth & Development ................................................. 2 8.8 Three Rivers ............................................................................. 78 4.3 Water Industry Infrastructure Investment & Planning ........... 3 8.9 Watford ..................................................................................... 83 4.4 The Water Environment, River Quality & Ecology ................. 6 8.10 Welwyn Hatfield ....................................................................... 88 4.5 Future Challenges ..................................................................... 8 9 SUB-CATCHMENT SOLUTIONS ............................ 93 4.6 Developing Sub-Catchment Solutions .................................. 11 9.1 Overview................................................................................... 93 5 SCOPE ..................................................................... 16 9.2 Amersham & Misbourne Valley (1) ........................................ 95 5.1 What is Included ...................................................................... 16 9.3 Ash Valley Rural Settlements (2) ........................................... 97 5.2 Exclusions ................................................................................ 16 9.4 Berkhamsted (3) ...................................................................... 97 5.3 Technical Challenges .............................................................. 17 9.5 Bishop’s Stortford (4) ............................................................. 98 5.4 Key Limitations & Uncertainty ............................................... 17 9.6 Chesham and Upper Chess Valley (5) ................................... 98 6 APPROACH ............................................................. 19 9.7 East Hatfield (6) ....................................................................... 98 6.1 Development & Growth Trends .............................................. 20 9.8 Harpenden (7) ........................................................................ 100 6.2 Wastewater Infrastructure ...................................................... 28 9.9 Hemel Hempstead and Bulbourne Valley (8) ...................... 100 6.3 Water Resources ..................................................................... 30 9.10 Hitchin and Letchworth Garden City (9) ............................. 102 6.4 River Water Quality ................................................................. 33 9.12 North East Hertfordshire Rural Settlements (10) ............... 103 7 STRATEGIC INFRASTRUCTURE ASSESSMENT .. 35 9.13 St Albans & Upper Colne Valley (11) ................................... 103 7.1 The Water System ................................................................... 35 9.14 Stevenage & Rural Area (12) ................................................ 106 7.2 Classification of Infrastructure Need .................................... 37 9.15 Tring (13) ................................................................................ 109 9.16 Watford Urban Area (14) ....................................................... 109 Definitions of Classification of Need for the Wastewater System 9.17 Welwyn Garden City and Hertford Growth Area (15) ......... 112 Definitions of Classification of Need for Water Resources 10 WATER MANAGEMENT AND POLICY PLANNING OPTIONS ................................................................ 115 Numerical Modelling Capacity and Performance Assessment 10.1 Current Context ..................................................................... 115 10.3 Supporting Sustainable Development ................................ 117 Hydraulic Modelling Methodology 10.4 Securing Continued Investment in Wastewater Infrastructure ..................................................................................... 118 10.5 Addressing Water Availability .............................................. 119 Mathematical Derivation of Population Projections 10.6 Maintaining Healthy Supply-Demand Balance ................... 119 10.7 Improving Water Quality ....................................................... 120 District Growth Strategies 11 FUNDING & INVESTMENT .................................... 122 11.1 Existing Funding Sources .................................................... 122 Interpretation of District Need Summary Plans 11.2 Suggested Supplementary Investment Models ................. 125 12 CONCLUSION & NEXT STEPS ............................. 127 Phase 2 Investigations & Modelling 12.1 Study Conclusions ................................................................ 127 12.2 District Conclusions.............................................................. 134 12.3 Sub-catchment Conclusions ................................................ 136 GLOSSARY 12.4 Next Steps .............................................................................. 140 See Section 13 13 GLOSSARY ............................................................ 146 APPENDICES Wastewater System Schematisation 1 EXECUTIVE SUMMARY potential future requirements, which incorporate neighbouring Arcadis Consulting (UK) were commission by Hertfordshire Council districts based on the need to address common water infrastructure in 2015 to undertake a strategic assessment of water infrastructure issues. Where there are significant infrastructure challenges and / to provide project partners, including local districts and the Water or growth pressures, strategic solutions have been proposed, Utility Companies, with evidence to support planning for growth over looking to enhance sustainability, improve long-term resilience and the next 35 years. promote innovation. The primary objectives of the study were to identify how future The greatest challenges that threaten the exploration of these sub- growth is likely to affect water infrastructure systems, what changes catchment solutions are growth uncertainties and the water are potentially needed to facilitate this growth and how could new infrastructure regulatory framework. Increasing confidence in systems impact the environmental. The secondary objective was to growth will be an instrumental in securing funding and enabling the identifying a range of options to meet local and strategic Water Utility Companies to minimise investment risks within the infrastructure needs, including a wider policy options. planning process. Where potential solutions could extend over A partnership was developed to underpin consultation and multiple Asset Management Plan (AMP) periods the Water Utility collaboration throughout the project, comprising the key local Companies will need to rely on more robust growth figures to administrative authorities (County Council, District Councils, support the preparation of long-term investment plans. Hertfordshire LEP), the Water Utility Companies (Thames Water, The outcomes of the study should help assist with the preparation Anglian Water and Affinity Water) and the Environment Agency. of Local Plans, clarify some of the uncertainty associated with To achieve these objectives the scale and location of growth, both growth expectations, help facilitate the participation of the Water known (within Local Plans) and anticipated, was clarified through Utility Companies in local planning and support strategic bids for consultation and the consolidation of multiple sources of population growth related funding. The options explored should be used to and housebuilding projections. A range of scenarios were used to assist in the planning of future water infrastructure systems and define key future timeframes and clarify uncertainty within the inform the next round of water resource plans and long-term assessment. High-level numerical and hydraulic modelling was strategies. used to derive an understanding of current and future system A 5-point action plan was derived to provide a framework to