Environment & Transport S19 Flood Investigation Report Engineering & Flood Risk Management Team Warrington Borough Council – Lead Local Flood Authority Date: December 2018 Location: Borough Wide Rainfall Event Flood Investigation Reference Number: 2018/019/001 Version: Final 01 Warringto n Borough Council – Environment & Transport S19 Flood Investigation Report: 2018/019/001 December Final01 Disclaimer Although every effort has been taken to ensure the accuracy of the information contained within the pages of this report, we cannot guarantee that the contents will always be current, accurate or complete. This report has been prepared as part of Council's responsibilities under the Flood and Water Management Act (2010) as Lead Local Flood Authority (LLFA). The findings of this report are based on a subjective assessment of the information available to those undertaking the investigation and therefore may not include all relevant information. Therefore it shouldn't be considered as a definitive assessment of all factors that may have triggered or contributed to the flood event. The opinions, co nclusions and any recommendations in this report are based on our assumptions when preparing this report, including, but not limited to those key assumptions noted in the reports, including reliance on information provided by third parties. The Council expressly disclaims responsibility for any error in, or omission from, this report arising from or in connection with any of the assumptions made being incorrect. The opinions, conclusions and any recommendations in these reports are based on conditions encountered and information reviewed at the time of preparation and the Council expressly disclaims responsibility for any error in, or omission from, this report arising from or in connection with those opinions, conclusions and any recommendations. The Council forbids the reproduction of this report or its contents by any third party without prior agreement. Control and Distribution This document is owned, maintained, and updated by the Engineering & Flood Risk Team, Warringto n Borough Council. All users are asked to advise the Engineering & Flood Risk Team of any changes in circumstances or information that may materially affect this investigation. Information should be sent to: Mr Jim Turton Engineering & Flood Risk Manager Warringto n Borough Council New Town House 3F Buttermarket Street Warrington WA1 2NH Tel: 01925 44 2542 E-mail: [email protected] This document will be reviewed following any new information being received in relation to the flood event and its causes/effects. i Warringto n Borough Council – Environment & Transport S19 Flood Investigation Report: 2018/019/001 December Final01 Revision Schedule & Approvals Originator: Approved by: Approved by: Revision Name Name Name Final 01 Jonathan Jim W Turton Tom Shuttleworth Dawson-Parry Date Signature Signature Signature December 2018 Position Position Position Asset & Flood Risk Engineering & Flood Infrastructure Engineer Risk Manager Delivery, Highways & Engineering Service Manager Document Status: Final01 Supporting Documents List ii Warringto n Borough Council – Environment & Transport S19 Flood Investigation Report: 2018/019/001 December Final01 Table of Contents Disclaimer .................................................................................................................................. i Control and Distribution .......................................................................................................... i Revision Schedule & Approvals ............................................................................................ ii Supporting Documents List.................................................................................................... ii 1 Introduction ....................................................................................................................... 1 2 Incident Summary ............................................................................................................ 2 2.1 Affected Areas ............................................................................................................. 2 3 Flood Incident Details ...................................................................................................... 3 3.1 Antecedent Co nditions ................................................................................................ 3 3.1.1 Rainfall Summary................................................................................................. 3 3.1.2 Soil Moisture Deficit ............................................................................................. 5 3.2 Rainfall Data ................................................................................................................ 6 3.3 Watercourse Data ..................................................................................................... 11 3.4 Weather / Flood Warning .......................................................................................... 14 3.5 Groundwater Conditions ........................................................................................... 19 4 Flooding Locations ........................................................................................................ 23 4.1 Campbell Crescent, Great Sankey ........................................................................... 23 4.1.1 Effects of the Flood Event.................................................................................. 23 4.1.2 Flood History ...................................................................................................... 23 4.1.3 Historic Mapping ................................................................................................ 23 4.1.4 United Utilities Statutory Sewer Map ................................................................. 24 4.1.5 Long Term Flood Risk........................................................................................ 25 4.1.6 Flooding Mechanism Conclusion....................................................................... 26 4.1.7 Actions................................................................................................................ 26 4.2 Liverpool Road, Great Sankey .................................................................................. 27 4.2.1 Effects of the Flood Event.................................................................................. 27 4.2.2 Flood History ...................................................................................................... 27 4.2.3 Historic Mapping ................................................................................................ 29 4.2.4 United Utilities Statutory Sewer Map ................................................................. 30 4.2.5 Long Term Flood Risk........................................................................................ 31 4.2.6 Highway Maintenance Records ......................................................................... 32 4.2.7 Flooding Mechanism Conclusion....................................................................... 33 4.2.8 Actions................................................................................................................ 33 4.3 Fairfield Road, Stockton Heath ................................................................................. 34 4.3.1 Effects of the Flood Event.................................................................................. 34 4.3.2 Flood History ...................................................................................................... 34 4.3.3 Historic Mapping ................................................................................................ 34 4.3.4 United Utilities Statutory Sewer Map ................................................................. 35 iii Warringto n Borough Council – Environment & Transport S19 Flood Investigation Report: 2018/019/001 December Final01 4.3.5 Long Term Flood Risk........................................................................................ 36 4.3.6 Highway Maintenance Records ......................................................................... 37 4.3.7 Flooding Mechanism Conclusion....................................................................... 37 4.3.8 Actions................................................................................................................ 37 4.4 Sankey Street, Bewsey & Whitecross ...................................................................... 38 4.4.1 Effects of the Flood Event.................................................................................. 38 4.4.2 Flood History ...................................................................................................... 38 4.4.3 Historic Mapping ................................................................................................ 38 4.4.4 United Utilities Statutory Sewer Map ................................................................. 38 4.4.5 Long Term Flood Risk........................................................................................ 39 4.4.6 Highway Maintenance Records ......................................................................... 40 4.4.7 Flooding Mechanism Conclusion....................................................................... 40 4.4.8 Actions...............................................................................................................