Development Application - Part 2 of 2 - Report & Plans · OPW11/0116

                                International
                                Coastal                                                                                                    ^pner recd cot la


                                Management


TABLE OF CONTENTS

EXECUTIVE SUMMARY ...........................................................................................................................................................1


1.      BACKGROUND ................................................................................................................................................................ 3


2.       EXISTING SITUATION ..................................................................................................................................................... 5


3.      OPTION ASSESSMENT ................................................................................................................................................... 9
     3.1.   Option A - Do Nothing                                                                                                                                             9
     3.2.   Option B - Establish Erosion Limit Control Lines                                                                                                                13
     3.3.   Option C1 - Wall and Embayed Beach                                                                                                                              14
     3.4.   Option C2 - Groyne Field and Embayed Beach                                                                                                                      17
     3.5.   Option D1 - Submerged Upstream Closure                                                                                                                          20
     3.6.   Option D2 - Submerged Upstream & Downstream Closure                                                                                                             23
     3.7.   Option D3 - Training Wall with Submerged Upstream & Downstream Closure                                                                                          26
     3.8.   Option E - Combination                                                                                                                                          29


4.      RECOMMENDED OPTION ............................................................................................................................................. 33
     4.1.    Risk Assessment                                                                                                                                              33
     4.1.1.    Uncertainty                                                                                                                                                33
     4.1.2.    Variability in shoreline response                                                                                                                          34
     4.1.3.    Channel Evolution/ River Processes                                                                                                                         34
     4.1.4.    Impact on Shoals                                                                                                                                           34
     4.1.5.    Erosion of Mangroves                                                                                                                                       34
     4.1.6.    Flooding                                                                                                                                                   35
     4.1.7.    Flushing                                                                                                                                                   35
     4.1.8.    Swimmer safety near submerged closure                                                                                                                      35
     4.1.9.    Navigation                                                                                                                                                 35
     4.1.10.   Vandalism I Vessel impact with the structure                                                                                                               35
     4.1.11.   Structural aspects                                                                                                                                         35


5.      CONSTRUCTION MATERIALS ...................................................................................................................................... 36
     5.1.  Sand-filled geotextile containers                                                                                                                           36
     5.2.  Rock                                                                                                                                                        36
     5.3.  Comparison                                                                                                                                                  36


6.      PRELIMINARY DESIGN & COSTING ............................................................................................................................37
     6.1.   Submerged "Closure"                                                                                                                                   37
     6.2.   Training Wall                                                                                                                                         38
     6.3.   Revetment Wall                                                                                                                                        41
     6.4.   Groynes                                                                                                                                               42
     6.5.   Total Strategy                                                                                                                                        43
     6.6.   Staged Works                                                                                                                                          44



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