Heathfield Stage 1 Surface Water Management Plan
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Heathfield Stage 1 Surface Water Management Plan Final Report April 2015 East Sussex County Council County Hall St Anne's Crescent LEWES East Sussex BN7 1UE JBA Project Manager Rachel Huitson-Little Aberdeen House South Road Haywards Heath West Sussex RH16 4NG Revision History Revision Ref / Date Issued Amendments Issued to Tom Schindl (East Sussex Draft Report v1 / February County Council) N/A 2014 Early issue - still requires final JBA QA and sign off Draft Report v2 / February Minor text amendments Tom Schindl (East Sussex 2014 (following internal QA) Country Council Final Report v3 / March Minor text amendments Tom Schindl (East Sussex 2014 (following ESCC review) County Council) “Way Forward” section Tom Schindl (East Sussex Draft Report v4 / April 2014 amended following ESCC County Council) review Further text amendments Tom Schindl (East Sussex Final Draft v5 / April 2015 undertaken by ESCC County Council) Contract This report describes work commissioned by Nick Claxton, on behalf of East Sussex County Council, by a letter dated 15/03/2013. East Sussex’s representative for the contract was Tom Schindl. Jenny Hill and Matthew Roberts of JBA Consulting carried out this work. Prepared by .................................................. Jennifer Hill BSc MSc Analyst Reviewed by ................................................. Rachel Huitson-Little MSc CEnv MCIWEM C.WEM Director Purpose This document has been prepared as a Draft Report for East Sussex County Council. JBA Consulting accepts no responsibility or liability for any use that is made of this document other than by the Client for the purposes for which it was originally commissioned and prepared. JBA Consulting has no liability regarding the use of this report except to East Sussex County Council. Acknowledgements JBA would like to acknowledge and thank Wealden District Council, Southern Water, the Environment Agency and East Sussex County Council for all their assistance during this project. i List of Figures Figure 1-1: A map to identify the location of ordinary watercourses in Heathfield ................... 3 Figure 1-2: A figure to illustrate the integration of flood mechanisms. ..................................... 4 Figure 1-3: A map of Heathfield, the underlying geology and the surrounding constraints to development. ........................................................................................................ 5 Figure 3-1: The GeoPDF flood risk and recorded flooding incidents in Heathfield. ................. 12 Figure 3-2: A map of the flooding hotpot - Waldron Thorns ..................................................... 14 Figure 3-3: A photo from the site visit to Waldron Thorns showing a completely blocked gulley grate. .............................................................................................................. 15 Figure 3-4: A conceptual model to explain the surface water runoff problem in Heathfield ...... 15 Figure 3-5: A map of the flooding hotpot - Meadow Way ......................................................... 16 Figure 3-6: A map of area covered by the surface water flood risk quantification analysis ..... 17 Figure 3-7: The total number of receptors affected by deep water flooding at a 1 in 200 year return periods ................................................................................................... 19 Figure 4-1: Strategic development areas identified in Heathfield. ............................................ 20 Figure 5-1: Action plan flow diagram, applicable where asset condition has been attributed as the flood source. .................................................................................................. 26 List of Tables Table 1-1 Report layout ............................................................................................................. 7 Table 2-1 Partners involved in the SWMP process ................................................................... 8 Table 2-2 Stakeholders involved in the SWMP process ........................................................... 8 Table 2-3 Catchment data and data supplier ............................................................................ 9 Table 2-4 Flood risk modelling data and supplier ...................................................................... 9 Table 2-5 Data quality scoring system ...................................................................................... 10 Table 2-6 Received data and allocated quality score ................................................................ 10 Table 3-1 Source of flooding colour coding system .................................................................. 12 Table 3-2 Sewer flooding incidents, colour coding system ....................................................... 13 Table 3-3 Number of receptors in Heathfield at risk from surface water flooding ..................... 17 Table 3-4 Number of receptors in Waldron Thorns, Heathfield at risk from surface water flooding ..................................................................................................................... 18 Table 3-5 Number of receptors in Meadow Way, Heathfield at risk from surface water flooding ..................................................................................................................... 18 Table 3-6 Number of receptors in the flooding hotspots within Heathfield that are at risk of surface water flooding .............................................................................................. 19 Table 5-1 Asset condition grade assessment taken from the Condition Assessment Manual ...................................................................................................................... 25 Table 5-2 Site specific actions priories according to repeated incidents occurring after 2000……………………………………………………………………………..…..27 ii Abbreviations AONB .............................. Area of Outstanding Natural Beauty AStGWF .......................... Areas Susceptible to Ground Water Flooding AStSWF .......................... Areas Susceptible to Surface Water Flooding BGS ................................ British Geological Society CAM ................................ Condition Assessment Manual CFMP .............................. Catchment Flood Management Plan CIL .................................. Community Infrastructure Levy DAP ................................. Drainage Area Plan DRN ................................ Digital River Network FRA ................................. Flood Risk Assessment ESCC .............................. East Sussex County Council FMfSW ............................ Flood Map for Surface Water LLFA ............................... Lead Local Flood Authority LFRMS ............................ Local Flood Risk Management Strategy NLPG .............................. National Land and Property Gazetteer NRD ................................ National Receptors Database RFCC .............................. Regional Flood and Coastal Communities RMA ................................ Risk Management Authority SAB ................................. SUDS Approving Body SDA ................................. Strategic Development Area SFRA .............................. Strategic Flood Risk Assessment SUDS .............................. Sustainable Drainage Systems SWMP ............................. Surface Water Management Plan uFMfSW .......................... updated Flood Map for Surface Water iii Contents Executive Summary ................................................................................................................. .Error! Bookmark not defined. List of Figures……………………………………………………………………………….…….…..ii List of Tables……………………………………………………………………………...……...……ii Abbreviations……………………………………………………………………………..…………..iii 1 Introduction ................................................................................................................. 1 1.1 What is a surface water management plan .................................................................. 1 1.2 Summary of aims and objectives .................................................................................. 1 1.3 Stages of SWMP development ..................................................................................... 2 1.4 Sources of flood risk ..................................................................................................... 2 1.5 Study area .................................................................................................................... 4 1.6 Using this report ............................................................................................................ 7 2 Preparation .................................................................................................................. 8 2.1 Partnership approach ................................................................................................... 8 2.2 Data collation and review.............................................................................................. 8 2.3 Source Pathway Receptor ............................................................................................ 11 3 Communicating the risk ............................................................................................. 11 3.1 GeoPDF ........................................................................................................................ 11 3.2 Priority areas ................................................................................................................