appendix a - National Grid

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TEP on behalf of National Grid 14 of 21 King’s Lynn 400kV Connection 110488-FRA-R1(1) The Hazard Zone is also known as the Rapid Inundation Zone, which is defined by the EA as areas of land behind both fluvial and tidal defences, which flood flow velocities, exceed 0.5m/sec or the depth of flooding exceeds 0.25m. Most of the Hazard Zone created is as a direct result of a breach for up to the 100-year (fluvial)/ 200-year (tidal) situation. Hazard Zones have been mapped for the King’s Lynn and West Norfolk SFRA and reproduced as Figure 7. This shows that the southern part (to the southeast of Dairy Farm) of the site is located in this zone.
9 POTENTIAL IMPACTS TEP on behalf of National Grid 15 of 21 King’s Lynn 400kV Connection 110488-FRA-R1(1) As the site is within a SFRA identified Flood Zone with climate change included, the main criterion for assessment is to determine the extent of any predicted flooding on the site as well as the influence of the proposed site drainage on local watercourses and any effects that the proximity of the flood zone may have on the pylons. In accordance with PPS25 (Ref. 1) and advice from the EA, a prediction of flood levels is required along with the effects of climate change from the present for the design life of the development. To consider the effect of climate change, PPS25 Annex B Table B2 (TABLE 9) recommends a consideration of a 20% increase in rainfall intensity and 20% increase in peak river flows for the proposed development. 9.1 Construction Activities Construction of the site should not influence the flooding regime and defences in the area. The following items should be considered: a) Construction and excavation works in the vicinity of the existing watercourses will have to be carried out to ensure no damage to the structure or blocking of the watercourse occurs. b) Any works near the flood defences must be carried out to ensure there is no negative effect on the integrity of the defence structures. c) Care will need to be taken during construction phase to reduce the risk of accidental spillage that could lead to the polluting of the nearby watercourse or underlying soils. In particular, direct surface water drainage connections into the watercourse or contaminated releases or silts into the existing drainage network. d) Safety of works should be considered with provision of emergency route and made aware of the EA flood line while working within the flood risk zones. Unpredictable weather may result in flash flood. 9.2 Proposal 9.2.1 Proposed Access It is proposed that construction activities will begin with preparation and installation of access to each pylon site. Existing accesses from public highways may need to be widened or temporary new accesses be constructed. Temporary tracks would be constructed on agricultural land using crushed stone and track way panels. Access to the site will be via the High Road from the north and the Thiefgate Lane from the south, which are then connected to the work areas through temporary stone roads as shown on the site layout in Figure 8. The work areas will result in crossing of the drainage ditches and the River Nar in the area. River scaffolds will be placed on both sides of the River Nar bank with pontoon to form crossings at the river. Any works, large or small, on the flood defence will have an effect on the integrity of the defence structure, therefore it should be avoided where possible. If it is not possible,
Page 1 and 2: 3.0 King’s Lynn B Power Station C
Page 3 and 4: CONTENTS 1 EXECUTIVE SUMMARY.......
Page 5 and 6: 1 EXECUTIVE SUMMARY TEP on behalf o
Page 7 and 8: 3 CONTEXT AND SCOPE OF WORK TEP on
Page 9 and 10: 4.3 Sequential Test Analysis TEP on
Page 11 and 12: 5.3 Geology TEP on behalf of Nation
Page 13 and 14: 7 SOURCES OF INFORMATION 7.1 Enviro
Page 15 and 16: TEP on behalf of National Grid 11 o
Page 17: 8.3 Flooding from Land (Overland Fl
Page 21 and 22: 9.2.4 Crossing TEP on behalf of Nat
Page 23 and 24: 10.5 Flood Plan TEP on behalf of Na
Page 25 and 26: 12 REFERENCES 1. Communities and Lo
Page 27 and 28: Relief Channel River Great Ouse Thi
Page 29 and 30: !H M etres 0 100 200 400 Key This m
Page 31 and 32: ( "This document has been prepared
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Page 36 and 37: TEP on behalf of National Grid King
Page 38 and 39: ANNEX E: THE ASSESSMENT OF FLOOD RI
Page 40 and 41: • A cross-section of the site sho
Page 42 and 43: APPENDIX C PPS 25 Annex D.1: Flood
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Page 46 and 47: APPENDIX D Environment Agency Corre
Page 48 and 49: Kings Lynn B Connection Project - Y
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Page 52 and 53: If you would like to discuss the ab
Page 54 and 55: Dear K. Cheng Our ref: CCN/2011/299
Page 56 and 57: Environment Agency Flood Zone Map c
Page 58 and 59: 2.0 Defence Information River Great
Page 60 and 61: Standard Notice [not for use with S
Page 62 and 63: Ka Yan Cheng From: Gerald Allison [
Page 64 and 65: APPENDIX F Borough Council of King
Page 66 and 67: would like to know if the council h
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Ordnance Survey Mapping © Crown Co
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APPENDIX H Details of Tower Types T
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