Flintshire Bridge Converter Station Flood Emergency Response Plan
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Flintshire Bridge Converter Station Flood Emergency Response Plan November 2019 Flood Emergency Response Plan Flintshire Bridge Converter Station i Quality information Prepared by Checked by Verified by Approved by Charlotte Clinton David Ritchie David Ritchie Associate Director Technical Director Technical Director Revision History Revision Revision date Details Authorized Name Position Draft Template 22/01/2019 Draft for review 30/10/2019 Final for issue 01/11/2019 Distribution List # Hard Copies PDF Required Association / Company Name AECOM Flood Emergency Response Plan Flintshire Bridge Converter Station ii Prepared for: National Grid Electricity Transmission Limited Lead HVDC Engineer Flintshire Bridge Converter Station Weighbridge Road Zone 4 Deeside Industrial Estate CH5 2LF Prepared by: AECOM Infrastructure & Environment UK Limited AECOM House 179 Moss Lane Cheshire, Altrincham WA15 8FH United Kingdom T: +44(0)1619 278200 aecom.com © 2019 AECOM Infrastructure & Environment UK Limited. All Rights Reserved. This document has been prepared by AECOM Infrastructure & Environment UK Limited (“AECOM”) for sole use of our client (the “Client”) in accordance with generally accepted consultancy principles, the budget for fees and the terms of reference agreed between AECOM and the Client. Any information provided by third parties and referred to herein has not been checked or verified by AECOM, unless otherwise expressly stated in the document. No third party may rely upon this document without the prior and express written agreement of AECOM. AECOM Flood Emergency Response Plan Flintshire Bridge Converter Station iii Table of Contents 1. Introduction ...................................................................................................... 1 2. Summary of the FCA and the requirements of Planning Condition 8 ............... 2 Flood Consequences Assessment ................................................................................................................... 2 FLIB Converter Station and ........................................................................................ 3 3. Flooding Mechanisms ...................................................................................... 3 Flooding from Rivers and Sea ........................................................................................................................... 3 Reservoir Flood Risk ......................................................................................................................................... 4 Surface Water Flooding ..................................................................................................................................... 4 4. Flood Warnings................................................................................................ 6 5. Response Actions ............................................................................................ 7 Alarms .............................................................................................................................................................. 7 Site Evacuation Procedures & Routes ............................................................................................................... 7 Reoccupation of the Site ................................................................................................................................... 8 6. Training & Exercising ....................................................................................... 9 7. Document Control .......................................................................................... 10 AECOM Flood Emergency Response Plan Flintshire Bridge Converter Station 1 1. Introduction 1.1 This document sets out the Flood Emergency Response Plan for Flintshire Bridge (FLIB) Converter Station as required by planning condition 8 of Planning Application Reference 050340. The document sets out the procedures that should be followed in the event of a flood alert and a targeted flood warning. The information and procedures that are set out in this document should be reviewed as minimum every three years and after a flood event. 1.2 The location of FLIB Converter Station including the access and egress route along Weighbridge Road is shown on Figure 1. Figure 1 Site Location 1.3 The document provides the information required by the Flood Consequences Assessment (FCA), December 2012 prepared for and submitted alongside Planning Application 050340 and is structured as follows: § Summary of the FCA and the requirements of Planning Condition 8; § FLIB Converter Station and flooding mechanisms; § Warning systems; § Response actions and evacuation arrangements § Training; and § Document control. AECOM Flood Emergency Response Plan Flintshire Bridge Converter Station 2 2. Summary of the FCA and the requirements of Planning Condition 8 2.1 Planning Condition 8 States: The Flood Emergency Response Plan as detailed at section 6.0 of the submitted Flood Consequences Assessment shall be implemented in full to a timeframe agreed beforehand by the Local Planning Authority. Reason: in the interests of flood alleviation and in compliance with Policy GEN1 of the adopted Flintshire Unitary Development Plan Flood Consequences Assessment 2.2 The Flood Consequences Assessment (FCA), December 2012 concluded that whilst the main site is at low risk of flooding from all sources including tidal flooding, the access and egress routes (along Weighbridge Road) to and from the site could be at risk of flooding during a flood event and therefore the FCA recommended the preparation of a flood plan including flood warning and evacuation plans. 2.3 Maintenance and/or other personnel who may be required to work at the converter station are expected to be highly trained and fully conversant with the risks associated with, and the procedures to be followed in response to a flood warning. The FCA concluded that the plan should ensure that: § Flooding mechanisms within the area of the site are understood (i.e. tidal, fluvial, surface water, groundwater and public sewers). § It is understood who does what during a flood event (Natural Resources Wales, Flintshire County Council, Emergency Services, Welsh Water, Electric, Gas and Telecommunication Companies etc.). § Registration is made to NRW’s Flood Warning Direct Service (if available) and that the flood warning codes are understood. § Evacuation arrangements are made which include: · Choosing a trigger when as to when to activate the flood plan (i.e. a flood depth). · Evacuation routes and evacuation centres are known in order to move to a safe place of refuge (see Section 6.1.3). 2.4 The FCA noted that it is important to test any flood plan by simulating a flooding event (by liaising with NRW) and regularly checking the flood plan to make sure it is kept up to date. It is also worth noting that National Grid Electricity Transmission (NGET) must ensure that any future occupiers of the site are aware of the flooding risks and consequences. AECOM Flood Emergency Response Plan Flintshire Bridge Converter Station 3 3. FLIB Converter Station and Flooding Mechanisms 3.1 Flintshire Bridge Converter Station forms part of the GB Electricity Transmission system linking the High Voltage Networks in North Wales and Scotland by use of a DC Submarine Cable. 3.2 The Converter Station Converts High Voltage DC to High Voltage AC for transmission forming a key part of the Network; as such during the detailed design and construction stages the Built Site Finish Level was raised to 8.675 AOD and all parts of the site itself are in a Low Risk area from all sources of flooding. 3.3 FLIB Converter Station will be staffed by 5 persons during normal work hours and 1 operator working a continuous three shift system 24 hours per day. All car parks, roads and amenities on the site are at low risk of flooding. Site amenities include full welfare facilities for up to 16 persons. 3.4 The Site is situated at the southern end of Weighbridge Road in Flintshire with the access road being in Flintshire County Councils private ownership south of it’s boundary with the adopted road network. The lowest point on the access road is at 4.745 AOD. This access road is in Zone 3 though it should be noted that the road itself is protected from flooding by rivers and the sea by flood defences. 3.5 The following sections provide information on how the different types of flooding relate to the site and the access road. Flooding from Rivers and Sea 3.6 FLIB Converter Station is located in Flood Zone 1 (land having less than a 1 in 1000 or 0.1% AEP of river or sea flooding) and therefore considered to be at low risk of flooding. 3.7 Sections of the access road along Weighbridge Road are located in Flood Zone 3 (land having a 1 in 100 (1%) or greater AEP of river flooding; or land having a 1 in 200 (0.5%) or greater AEP of sea flooding) and this. These areas are illustrated on Figure 2. Figure 2 NRWs Risk of Flooding from Rivers and Sea Mapping (downloaded 30-10-2019)1 1 https://maps.cyfoethnaturiolcymru.gov.uk/Html5Viewer/Index.html?configBase=https://maps.cyfoethnaturiolcymru.gov.uk/Geoc ortex/Essentials/REST/sites/Flood_Risk/viewers/Flood_Risk/virtualdirectory/Resources/Config/Default&layerTheme=0 AECOM Flood Emergency Response Plan Flintshire Bridge Converter Station 4 3.8 The site is also located within TAN15 Development Advice Map Zone B which indicates areas known to have been flooded in the past evidenced by sedimentary deposits. Sections of the access road along