Amber Valley Borough Council Level 1 Strategic Flood Risk Assessment
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Amber Valley Borough Council Level 1 Strategic Flood Risk Assessment Final Report October 2016 Amber Valley Borough Council Town Hall RIPLEY Derbyshire DE5 3BT This page is intentionally left blank. 2016s4674 - Amber Valley Borough Council - Level 1 SFRA FINAL v1.0.docx i JBA Project Manager Joanne Chillingworth The Library St Philip’s Courtyard Church End COLESHILL B46 3AD Revision History Revision Ref / Date Amendments Issued to Issued Draft Rev 1.0 / Sept DRAFT Noel Bell, Amber Valley Borough Council 2016 Naomi Doughty, Environment Agency Daniel Clancy, Environment Agency Daniel Killer, Derbyshire County Council Richard Campbell, Derbyshire County Council Chris Rodgers, Derbyshire County Council Final Rev 1.0 / Oct FINAL Noel Bell, Amber Valley Borough Council 2016 Contract This report describes work commissioned by Amber Valley Borough Council. The Council’s representative for the contract was Noel Bell. Prepared by .................................................. Sophie Dusting BSc Analyst ....................................................................... Freyja Scarborough BSc MSc Assistant Analyst Reviewed by ................................................. Joanne Chillingworth BSc MSc MCIWEM C.WEM Chartered Senior Analyst Purpose This document has been prepared as a Final Report for Amber Valley Borough 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 Amber Valley Borough Council. 2016s4674 - Amber Valley Borough Council - Level 1 SFRA FINAL v1.0.docx ii Acknowledgements We would like to acknowledge the assistance of: Derbyshire County Council, including Highways; Environment Agency; Canal and River Trust; Severn Trent Water; Fire & Rescue; and Planners at the neighbouring authorities. Copyright © Jeremy Benn Associates Limited 2016 Carbon Footprint A printed copy of the main text in this document will result in a carbon footprint of 511g if 100% post- consumer recycled paper is used and 651g if primary-source paper is used. These figures assume the report is printed in black and white on A4 paper and in duplex. JBA is aiming to reduce its per capita carbon emissions. 2016s4674 - Amber Valley Borough Council - Level 1 SFRA FINAL v1.0.docx iii Executive Summary Introduction This Strategic Flood Risk Assessment 2016 document replaces the Level 1 Strategic Flood Risk Assessment originally published by Amber Valley Borough Council in February 2009. The purpose of this study is to provide a comprehensive and robust evidence base to support the production of the Amber Valley Borough Council Local Plan. SFRA objectives The key objectives of Level 1 Strategic Flood Risk Assessment are: 1. To replace the Council's existing Level 1 Strategic Flood Risk Assessment, taking into account most recent policy and legislation in the National Planning Policy Framework. 2. To collate and analyse the latest available information and data for current and future (i.e. climate change) flood risk from all sources and how these may be mitigated. 3. To inform decisions on the emerging Local Plan including the selection of development sites and planning policies. 4. To provide supporting evidence to support the Council with the preparation of their Local Plan, allowing the application of the Sequential Test in the allocation of new development sites. 5. To provide a comprehensive set of maps presenting flood risk from all sources that can be used as evidence base for use in the emerging Local Plan. 6. To draw attention to advice for applicants carrying out site-specific flood risk assessments and outline specific measures or objectives that are required to manage flood risk to the appropriate standard. SFRA outputs Identification of policy and technical updates. Identification of any strategic flooding issues which may have cross boundary implications. Identification of any critical flood modelling and data gaps. Appraisal of all potential sources of flooding, including Main River, ordinary watercourse, surface water, sewers, groundwater, reservoirs and canals. Mapping showing distribution of flood risk across all flood zones from all sources of flooding including climate change allowances, including new and amended data sources. Review of historic flooding incidents. Identification of any specific locations within Amber Valley at risk of sewer flooding and if so, to consider whether there is a need for hydraulic modelling to be undertaken. Reporting on the standard of protection provided by defences. Assessment of surface water management issues and Sustainable Drainage Systems guidance. Flood Risk Assessment guidance for developers. Sequential Test guidance and sequential approach to flood risk. Assessment of strategic flood risk solutions that can be implemented to reduce risks. Summary of Level 1 Assessment Sources of flood risk Parts of Amber Valley are at risk from the following sources; fluvial, surface water, groundwater, sewers, reservoir inundation, canal overtopping / breaches. This study has shown that the most significant sources of flood risk in the borough are fluvial and surface water. Historic flood risk: Amber Valley has long history of flooding, from fluvial and more recently, pluvial sources. Significant borough-wide events occurred in 1932, 1947, 1965, 1977 and 2007. The majority of the historic fluvial flood events were primarily recorded from the River Derwent, Erewash and Ecclesbourne. Recent flood events in 2012 and 2014 have affected 2016s4674 - Amber Valley Borough Council - Level 1 SFRA FINAL v1.0.docx iv more rural communities including Lower Hartshay, Derwent Grove in Alfreton, Duffield, Smalley, Heage and South Wingfield and have tended to be from fluvial and pluvial sources. Fluvial flooding: The primary fluvial flood risk is along the River Derwent and its tributaries including the River Ecclesbourne corridor. These present fluvial flood risk to rural communities as well as to the main urban centres in Amber Valley. In general, these watercourses have narrow Flood Zones in areas of high ground in the north-west, confining the flood extents and wider Flood Zones elsewhere, as there are larger expanses of floodplain and shallower gradients. Surface water: The updated Flood Map for Surface Water shows a number of prominent overland flow routes; these predominantly follow topographical flow paths of existing watercourses or dry valleys with some isolated ponding located in low lying areas. The updated Flood Map for Surface Water shows that the majority of settlements in Amber Valley have a degree of surface water flood risk; whilst, in the majority of cases, the risk is confined to roads, there are notable, prominent flow routes around properties e.g. at the foot of surrounding hills. Sewer: The sewers are managed by Severn Trent Water. The DG5 register of recorded historical sewer flooding was supplied and indicates a total of 363 recorded incidences of sewer flooding in Amber Valley administrative area from July 1999. The settlements with the most recorded incidents include Belper, Heanor and Ripley. Settlements such as Cowhill, Duffield, Ironville, Langley Mill, Heanor and Kilburn may be vulnerable to sewer flooding. Groundwater: There are limited records of groundwater flooding in the borough. The Areas Susceptible to Groundwater Flooding map shows that the majority of the borough is within the <25% classification which is consistent with the underlying bedrock geology. Locations of comparatively greater groundwater susceptibility are located towards the south-west, along the River Ecclesbourne and Cutler Brook / Markeaton Brook corridors. There is an extensive history of mining in Amber Valley; however, the Areas Susceptible to Groundwater Flooding dataset does not account for the potential influence mining activities may have on flood risk. It is noted that there are two soughs located near Crich; these could act as an additional pathway for groundwater. Canals: There are three canals in the borough: the Erewash Canal, the Cromford Canal, and the Nutbrook Canal. These have the potential to interact with other watercourses and become flow paths during flood events or in a breach scenario. Historical evidence shows that the Erewash Canal at Langley Mill interacts with the River Erewash. The Canal & River Trust note that there are a number of risks along the Erewash Canal including deliberate misuse, culvert blocking and / or failure and embankment failure. Reservoirs: There are 17 reservoirs located within Amber Valley and includes those located outside the administrative boundary and whose inundation mapping is shown to affect Amber Valley. It is important to note that there are no records of flooding from reservoirs in the study area. The level and standard of inspection and maintenance required under the Reservoirs Act means that the risk of flooding from reservoirs is relatively low. However; there is a residual risk of a reservoir breach and this risk should be considered in any site- specific Flood Risk Assessments (where relevant). Emergency planning considerations have been included and the flood warning service coverage assessed; currently five Flood Alert Areas and 18 Flood Warning Areas cover parts of the Amber Valley area. Requirements for safe access and egress have also been set out. Defences A review of existing flood defences was undertaken