Chapter 9: Road drainage and the water environment

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M1 JUNCTION 19 IMPROVEMENT ENVIRONMENTAL STATEMENT VOLUME 2 CHAPTER 9 – ROAD DRAINAGE AND THE WATER ENVIRONMENT Table 9.13: M1 Junction 19 Water Environment Features Summary: Operation Effects................ 41 FIGURES Figure 9.1 Figure 9.2 Figure 9.3 Figure 9.4 Figure 3.13 Existing Hydrological Features Existing Drainage Zones Proposed Drainage Zones Typical Pond Layout River Avon Flood Compensation and Otter Mitigation APPENDICES Appendix A Appendix B Appendix C Pollution and Spillage Risk Calculations Glossary of Technical Terms Flood Risk Assessment Page ii
M1 JUNCTION 19 IMPROVEMENT ENVIRONMENTAL STATEMENT VOLUME 2 CHAPTER 9 – ROAD DRAINAGE AND THE WATER ENVIRONMENT 9.1 INTRODUCTION 9.1.1 This chapter is an assessment of the potential environmental effects of the proposed M1 Junction 19 Improvement on road drainage and the water environment. It comprises the environmental assessment of surface water, groundwater and flood risk during both construction and operation of the scheme. It includes calculations in line with the Design Manual for Roads and Bridges (DMRB) Volume 11, Section 3, Part 10, Annex 1. The chapter also provides recommendations for best practice and mitigation based on the outcomes of the assessment. 9.1.2 In common with other Chapters, the Road Drainage and the Water Environment assessment recognises that the Catthorpe Viaduct, which carries the M6 to M1 Southbound link over the M1, is being replaced as a maintenance project. The scope of this work includes the replacement of the bridge on a new alignment immediately to the south west of the existing. It also requires the creation of new approach embankments either side of the M1. The work is programmed to begin in June 2010, for completion in November 2011. 9.1.3 The bridge and earthworks either side of the M1 would be retained in the proposed layout for the M1 Junction 19 Improvement, as would the alignment of the M6 to M1 Southbound link east of the M1. To the west of M1 this link would have to be amended to accommodate the proposed M6 to A14 link. 9.1.4 A separate environmental assessment 49 has been carried out for the bridge replacement as a stand alone maintenance project. 9.1.5 This ES for the M1 Junction 19 Improvement takes into account the new bridge both:- • As part of the existing junction, assuming the M1 Junction 19 Improvement is not built; the ‘do-minimum’ scenario • As part of the completed M1 Junction 19 Improvement; the ‘do-something’ scenario. 9.1.6 In terms of road drainage and the water environment, the proposals for the viaduct replacement will be to match the existing drainage arrangements as far as possible, with only negligible differences in the locations of pipes and gulleys. There will also be some reduction in the highway area to be drained as the replacement viaduct will be narrower than the existing. 9.1.7 These issues are dealt with in Section 9.6 Environmental Impact. Objectives 9.1.8 The objectives for the road drainage and water environment assessment are:- • To protect the water environment • To reduce the risk of pollution and flooding 9.1.9 In addition, there is a general scheme objective that the impact on the natural and built environment should be minimised. It is also considered that appropriate measures should be taken and best practice followed during and after construction, by the use of sustainable drainage techniques. B0531000_ID_70-EIA Vol 2 Chap 9 Road Drainage and the Water Environment Final Rev 4.doc Page 1
Page 1: M1 Junction 19 Improvement Environm
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M1 JUNCTION 19 IMPROVEMENT ENVIRONM
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Appendix A - Pollution and Spillage
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Method D - Assessment of Pollution
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Groundwater: Hydrocarbons Hydrogeol
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Non Technical Summary Skanska Const
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Contents 1 Introduction 1 1.1 Overv
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1 Introduction 1.1 Overview Jacobs
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2 Policy Review 2.1 Planning Contex
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When the both the ‘Flood Zone’
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3 Flood Risk to the Proposed Develo
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3.2 Fluvial Flooding - Ordinary Wat
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Major earthworks affecting surface
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3.7 Flooding from Infrastructure Fa
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3.9 Summary of Risks to Site Table
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4 Impacts of the Proposed Developme
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4.6 Summary of Flood Impacts from D
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5 Proposed Mitigation Measures 5.1
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The extents of this problem are cur
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5.7 Summary of Recommended Mitigati
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6 Residual Risks The level of flood
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7 PPS25 Sequential and Exception Te
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8 Conclusion The M1 Junction 19 Imp
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Appendix A Existing Layout, Environ
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Appendix B Contractor’s Proposals
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Appendix C Hydrogeological Assessme
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Memorandum Fairbairn House, Ashton
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Memorandum (Continued) Page 3 of 6
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Memorandum (Continued) Page 5 of 6
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Appendix D Volume Distribution for
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Floodplain compensation area - elev
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Depth Bands (m) TOTAL (m³) Area Re
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Chapter 9: Road drainage and the water environment

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