LOCAL SEDIMENT MANAGEMENT AT LEEWARD-GOING-THROUGH IN PROVIDENCIALES, TURKS AND CAICOS

摘要

Dredged material was transferred from the borrow site to the beach via a pipeline cutter suction dredge. Approximately 260,000 m~3 of material was taken from the borrow area and placed on the beach. Survey transects were used to ensure complete sediment removal. The same transects continue being used to determine shoal evolution and migration. The project significantly widened and improved the severely eroded Emerald Beach shoreline by the placement of approximately 240,000 m~3 of high quality sand. The immediate post-construction survey data for the beach profiles is scheduled to be resurveyed 6 months following the initial construction project, or in February 2005. This new information will be compared to the immediate post-construction survey data to determine the shoreline change rates and the volumetric change rates. A physical and biological monitoring plan for the Emerald Beach Sand Replenishment Project has been implemented to measure and evaluate the physical and biological systems within the nearshore coastal areas surrounding Leeward-Going-Through. The purpose of the post-Project monitoring studies are to evaluate the Project's overall performance and to determine the long-term beneficial and/or adverse impacts of the Project on the coastal environment. The results of the measured changes will be used to determine if erosion amelioration measures and mitigation is required. Water Cay, immediately north of Little Water Cay and connected by Donna Cut, was planned for development requiring an access channel be dredged to move construction equipment onshore. An environmental impact statement and construction drawings were developed to satisfy outline planning needs while in depth site investigations were conducted finalizing channel alignment and sediment containment location. Sediment analysis indicated beach compatible sand and beach nourishment was planned. The complexity of site investigations, design, and management of coastal engineering projects that utilize hydraulic dredging were experienced firsthand, teaching many lessons either not taught or are impossible to teach in a university setting. All projects were relatively uneventful, considering the remote location and complex working environment. Recognition of the local interests regarding the property owner rights, government planning interests, marine environment, dredge contractor, and client all were found to be essential to effective project management. The first-hand professional experiences were invaluable for a contemporary engineering education.