Oceanographic surveys of tidal inlets for oil spill response.
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The need for rapid, detailed oceanographic surveys of tidal inlets for contigency planning became apparent during the Ixtoc I and Burmah Agate oil spills in 1979. Tidal inlets, which exist along virtually all coastal plain shorelines, provide the major conduits for open ocean spills to enter environmentally sensitive coastal habitats. During Ixtoc I and Burmah Agate, a significant effort was made to combine scientific expertise with the practical expertise of the U.S. Coast Guard (USGC) Strike Teams to design more efficient and appropriate boom configurations for Texas passes. Information on tidal inlets, needed by the Strike Teams, included distribution of surface currents, duration and time of flood currents, updated bathymetry, and location of low-velocity zones or natural oil traps. Based on the Texas experience, techniques were developed to survey major tidal inlets rapidly, prepare detailed boom and skimmer deployment, and coordinate implementation of each plan with private cleanup contractors. The surveys were designed to improve the performance and efficiency of containment equipment. Site-specific plans for inlet protection were prepared for Brazos-Santiago Pass, Mansfield Pass, Aransas Pass, and Pass Cavallo during Ixtoc I. During the Burmah Agate incident, design for protecting San Luis Pass and Galveston Entrance, two of the largest inlets in Texas, were prepared within 10 days after the spill, using aerial reconnaissance and hydrography studies. The schemes took advantage of natural circulation patterns and identified most likely oil trajectories and impact zones within each pass. Contingency plans for Texas inlets were site-specific and attempted to balance the need to protect sensitive lagoon environments with the need to maintain commercial navigation within the practical limitations of equipment and manpower available.