Eastern Bays Shared Path: Assessment of Environmental Effects for Intertidal Ecology EOS Ecology Report No.HUT01-17050-01 | March 2019 Eastern Bays Shared Path: Assessment of Environmental Effects for Intertidal Ecology EOS Ecology Report No.HUT01-17050-01 | March 2019 Prepared for Hutt City Council Prepared by EOS Ecology Shelley McMurtrie Kirsty Brennan Reviewed by Gary Stephenson (Coastal Marine Ecology Consultants) Alex James (EOS Ecology) EOS ECOLOGY | SCIENCE + ENGAGEMENT EXECUTIVE SUMMARY ............................................................................ 1 1 INTRODUCTION ................................................................................ 4 2 METHODS ......................................................................................... 7 2.1 Determination of Proposed Seawalls and Area of Works ............................. 7 2.2 Habitat Types – Broad Scale ......................................................................... 7 2.3 Intertidal Ecology .......................................................................................... 9 2.4 Sediment Contamination ............................................................................ 13 2.5 Data Analysis .............................................................................................. 13 3 EXISTING STATE OF THE ENVIRONMENT ...................................... 15 3.1 Existing Seawalls ........................................................................................ 15 3.2 Hydrodynamics and Sediment Transport .................................................... 21 3.3 Habitat Types – Broad Scale ....................................................................... 23 3.4 Intertidal Ecology (Benthic Invertebrates and Macroalgae) ....................... 26 3.5 Sediment Contamination ............................................................................ 42 4 OVERVIEW OF DESIGN AND CONSTRUCTION METHDOLOGY ...... 44 4.1 Proposed Seawalls and Shared Path Concept ............................................ 44 4.2 Overview of Construction Methodology ..................................................... 51 5 ASSESSMENT OF ENVIRONMENTAL EFFECTS .............................. 53 5.1 Construction Effects .................................................................................... 53 5.2 Operational Effects ...................................................................................... 56 6 RECOMMENDED MITIGATION ....................................................... 70 6.1 Construction Phase Mitigation Measures .................................................. 70 6.2 Operational Phase Mitigation Measures .................................................... 72 7 ACKNOWLEDGMENTS .................................................................... 77 8 REFERENCES .................................................................................. 77 9 APPENDICES ................................................................................... 83 9.1 Appendix 1 – Detailed Map of Proposed Seawall Types ............................ 83 9.2 Appendix 2 – Habitat Maps – Broad Scale Assessment ............................. 86 9.3 Appendix 3 – EOS Ecology Ecological Survey Sites .................................... 92 9.4 Appendix 4 – Benthic Invertebrate Fauna Overview .................................. 94 EOS ECOLOGY | SCIENCE + ENGAGEMENT EOS ECOLOGY | SCIENCE + ENGAGEMENT Eastern Bays Shared Path: Assessment of Environmental Effects for Intertidal Ecology 1 EXECUTIVE SUMMARY $!#% %&%%%* &01%#$! 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