Flintshire Bridge Converter Station

Flood Emergency Response Plan

November 2019 Flood Emergency Response Plan 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 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.

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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.

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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.

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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 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

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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 Weighbridge Road are located within Zone C1 which indicates areas of floodplain which are developed and served by significant infrastructure including flood defences. These areas are illustrated on Figure 3.

Figure 3 TAN15 Development Advice Map Extract (downloaded 30-10-2019)2

Reservoir Flood Risk 3.9 Neither the site or access road is currently are at risk of reservoir flooding.

Surface Water Flooding 3.10 Sections of the access road along Weighbridge Road are located in a high risk area for surface water flooding. These areas along with the direction of flow are shown on Figure 4.

2 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=2

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Figure 4 Surface Water Flooding High Risk Areas (downloaded 30-10-2019)3

3 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

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4. Flood Warnings

4.1 National Grid Transmission Network control Centre monitors weather and flood alerts for the whole of the GB transmission network. Monitoring incorporates Met office weather warnings, Flood Forecasting Centre Flood Guidance Statements, Met Office Hazard Manager and the Environment Agencies Targeted Flood Warning Service.

4.2 The location of FLIB Converter Station and the low point of the access road is mapped into the various relevant systems including the Environment Agencies Targeted Flood Warning Service.

4.3 On detection of a flood alert or targeted flood warning the Transmission Network Control Manager or his nominee shall inform the FLIB Converter Station Control Room and implement the procedures set out in Section 5 as appropriate.

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5. Response Actions

Alarms Flood Alert

5.1 On receipt of a flood alert the National Grid Electricity Transmission control room will inform the Flintshire Bridge Shift Operator who in turn will inform the Lead HVDC engineer or their delegated site representative that an alert is in place and that personal on site should remain vigilant, continue to monitor the situation and be prepared to evacuate the site. This process is set out below.

Lead HVDC NGET Control FLIB Shift Flood Alert engineer to be Room to inform Operator to issued to NGET prepared to FLIB Shift inform the Lead Control Room implement the Operator HVDC engineer evacuation plan

Targeted Flood Warning

5.2 On receipt of a targeted flood warning the National Grid Electricity Transmission control room will inform the Flintshire Bridge Shift Operator who in turn will inform the Lead HVDC engineer or their delegated site representative that a warning is in place and that the site should be evacuated. The Lead Engineer will appoint a Site Incident Controller who will ensure that all site personnel and visitors are accounted for by taking a roll call.

Lead HVDC Targeted flood FLIB Shift engineer to NGET Control warning Operator to appoint a site Room to inform issued to inform the incident FLIB Shift NGET Control Lead HVDC controller who Operator Room engineer will implement the evacuation plan

Site Evacuation Procedures & Routes 5.3 Should the site need to be evacuated the following process will be followed:

5.4 The Site Incident Controller will assess Weighbridge Road to ensure safe passage can be made and will ensure that all personnel leave site without delay. It is considered that by taking such early action it will be safe for normal road vehicles to pass.

5.5 If the Incident Controller considers that water level may inhibit the use of low cars etc. he shall report back to the National Grid Control Centre and trigger the next stage of National Grid’s resilience plan which in the first instance will involve the use of all-terrain vehicles to make safe passage along weighbridge road.

5.6 The Incident controller will further account for all personnel having safely passed weighbridge Road by a second roll call.

5.7 If for any reason safe passage cannot be made via Weighbridge Road emergency evacuation will take place via the adjacent steel site land to the southwest of the built platform.

5.8 This procedure shall be detailed and maintained within a suite of documents comprising the site emergency plan as specified by National Grid Transmission Procedure.

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Safe Refuge

5.9 If, for any reason all flooded evacuation routes are impassable all areas of the converter station provide safe refuge; mess facilities and welfare amenities are available for 16 Persons. Communication channels include PSTN, Private telephony and data communications facilitated by multiple segregated routes. Further rescue efforts will be co-ordinated by National Grid area resilience teams in co-ordination with other government agencies and emergency services.

Reoccupation of the Site 5.10 As the site is fully remotely controllable and not liable to flood the Link will remain an essential part of the GB transmission system. If for any reason access is required prior to normal levels resuming National Grids Northwest Area Resilience plan will be invoked and the Zonal Incident Controller will, in conjunction with other agencies make suitable arrangements for entry.

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6. Training & Exercising

6.1 All individuals who work at FLIB Converter Station should be made aware of this plan and briefed / trained accordingly. Exercising of this plan / personnel capabilities is essential to ensure all individuals have knowledge of what to do.

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7. Document Control

7.1 This Plan is owned, maintained, and updated by National Grid. All users are asked to advise of any changes in circumstances that may materially affect the plan in any way.

7.2 The plan will be reviewed at least every three years, as a result of lessons identified after an activation event or exercise, following changes ownership of the property or following any change to the flood risk or warning processes.

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