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Flood Investigation Report- Kelleythorpe and Driffield Showground During winter 2012 - 2013 Revision Schedule East Riding of Yorkshire Council Flood Investigation Report Kelleythorpe and Driffield Showground during Winter 2012/2013 CES\D200\LDES\1808 **/**/**** Rev Date Details Author Checked and Approved By 0.1 1 Initial Draft AMM 0.2 11/10/13 Revised Draft GP/AMM [Type text] Flood Investigation Report- Kelleythorpe and Driffield Showground During winter 2012 - 2013 Copyright Notice Maps in this report are reproduced from Ordnance Survey material with the permission of Ordnance Survey on behalf of Her Majesty’s Stationery Office Crown copyright 2008. Unauthorised reproduction infringes Crown copyright and may lead to prosecution or civil proceedings. East Riding of Yorkshire Council 100023383. Records of the public sewer system included are a facsimile of the statutory record provided by Yorkshire Water Services. For the purposes of this report minor sewers and other non relevant data have been omitted from the plans for clarity. The statutory public sewer record is held by Yorkshire Water Services Ltd. Acknowledgement East Riding of Yorkshire Council would like to thank members of the Driffield Agricultural Society (DAS), for their co-operation and assistance throughout this investigation. CES\D200\LDES\1808 3 Flood Investigation Report- Kelleythorpe and Driffield Showground During winter 2012 - 2013 Table of Contents Page Lead Local Flood Authority and Responsibilities ............................................................................. 5 Relevant Flood Risk Management Authorities................................................................................ 5 Abbreviations: ................................................................................................................................. 7 1. Executive Summary ........................................................................................................................ 8 1.1 Location of Flooding .............................................................................................................. 9 2. The Drainage System .................................................................................................................... 12 2.1 The Land Drainage System .................................................................................................. 12 2.2 Flooding History ................................................................................................................... 13 3. The Flooding Event ....................................................................................................................... 14 3.1 Conditions before the event ................................................................................................ 14 3.2 The Event ............................................................................................................................. 15 3.3 Causes and Investigation Findings ....................................................................................... 18 4. Conclusions ................................................................................................................................... 23 5. Recommendations ........................................................................................................................ 24 Useful Links and Contact Details: .................................................................................................. 25 Appendices: ........................................................................................................................................... 26 Appendix 1 Monthly rainfall and groundwater levels .................................................................. 27 Appendix 2 Aerial photograph of event ....................................................................................... 28 Appendix 3 Groundwater levels from 2010 to present ................................................................ 29 Appendix 4 Historic groundwater levels ....................................................................................... 30 Appendix 5 Geology of the area .................................................................................................... 31 Appendix 6 Location plan (A3) ...................................................................................................... 32 Appendix 7: Showground culvert location .................................................................................... 33 CES\D200\LDES\1808 4 Flood Investigation Report- Kelleythorpe and Driffield Showground During winter 2012 - 2013 Lead Local Flood Authority and Responsibilities East Riding of Yorkshire Council, as the Lead Local Flood Authority (LLFA), has a responsibility under Section 19 of the Flood and Water Management Act 2010 to investigate significant flood incidents in its area. Section 19 states: (1) On becoming aware of a flood in its area, a lead local flood authority must, to the extent that it considers it necessary or appropriate, investigate — (a) which risk management authorities have relevant flood risk management functions, and (b) whether each of those risk management authorities has exercised, or is proposing to exercise, those functions in response to the flood. (2) Where an authority carries out an investigation under subsection (1) it must— (a) publish the results of its investigation, and (b) notify any relevant risk management authorities. (3) The LLFA has lead responsibility for managing the risk of flooding from surface water, groundwater and ordinary water courses. This report has been prepared by the East Riding of Yorkshire Council in its role as LLFA in response to extensive flooding which affected properties in Gott Close, Montgomery Square, Driffield Rugby Club and Driffield Showground in the winter of 2012-13. This report provides details and an overview of flooding that has occurred, describes the conditions which led to the flooding, considers the response to the flooding thus far and makes technical recommendations for the flood risk authorities concerned. Relevant Flood Risk Management Authorities The relevant parties that have relevant flood risk management responsibilities are: East Riding of Yorkshire Council East Riding of Yorkshire Council is the Lead Local Flood Authority responsible for managing flood risk from surface runoff, groundwater and ordinary watercourses, development of a Local Flood Risk Strategy, Asset Plans and Investigations under the Flood & Water Management Act 2010. East Riding of Yorkshire Council is also the Highway Authority with responsibility for highway drainage under the Highway Act 1980. Environment Agency Responsible for managing the Flood risk from main rivers, the sea and reservoirs including coastal erosion risk management, permissive powers to maintain Main Rivers, Strategic Overview over all forms of flooding and development of a national Flood Risk Strategy. CES\D200\LDES\1808 5 Flood Investigation Report- Kelleythorpe and Driffield Showground During winter 2012 - 2013 Yorkshire Water Yorkshire Water Services is the statutory sewerage undertaker for the Yorkshire region with a duty to effectually drain sewers pursuant to the Water Industries Act 1991. Additionally: Riparian Landowners Riparian landowners are those who own land adjoining a watercourse and have certain responsibilities, including the following: • They must maintain the bed and banks of an open watercourse, and also the trees and shrubs growing on the banks. • They must clear any debris, even if it did not originate from their land, this debris may be natural or man-made. • They must keep any structures that they own clear of debris. These structures include culverts, trash screens, weirs and mill gates. If they do not carry out their responsibilities, they could face legal action under the Land Drainage Act 1991. Details of a riparian landowners responsibilities can be found in “Living on the Edge” published by the Environment Agency. CES\D200\LDES\1808 6 Flood Investigation Report- Kelleythorpe and Driffield Showground During winter 2012 - 2013 Abbreviations: AOD Above Ordnance Datum CCTV Survey using Closed Circuit Television camera travelling through a pipe or culvert. CSO Combined Sewer Overflow DAS Driffield Agricultural Society EA Environment Agency ERYC East Riding of Yorkshire Council GWL Ground Water Level m metres MH Manhole YWS Yorkshire Water Services Ltd CES\D200\LDES\1808 7 Flood Investigation Report- Kelleythorpe and Driffield Showground During winter 2012 - 2013 1. Executive Summary The flooding in Kelleythorpe was unusual in that it was not as a result of a single rainfall event but due to the cumulative effect of rainfall over a prolonged period. During 2012, persistent wet weather (second wettest year on record in England, see Appendix 1) resulted in exceptionally high water levels in the whole area and in particular the River Hull catchment which includes the Driffield area. With high water levels in the River Hull, combined with elevated groundwater levels in the chalk, the groundwater was not able to drain away into the river and so remained at elevated levels for some time. This led to many seasonal springs rising across the area and exceptionally high flows in various watercourses on the Wolds, with surface and property flooding in many places including parts of Driffield and Kelleythorpe, as well as the inundation of the foul sewer system. Significant areas of farmland were also flooded