Dade County, Florida Deep Water Sand Search Study: Fid-Bau Portal

Dade County, Florida Deep Water Sand Search Study

Andrews, Jeffrey L.

A combined geophysical and geotechnical study was conducted at a reconnaissance level in order to determine the potential for recovery of beach quality sand in the deep water area of Dade County beyond the outer reef line. The geophysical survey plan included 121 track lines covering a total of approximately 150 line-miles over a total area of more than 15 square miles. The reconnaissance study area can be broadly divided into three sub-sections according to depth and corresponding lithology. The three sub-sections lie generally in the depth ranges of 55–110 feet, 130 to 240 feet and 250 to 300 feet. The division between the two deep-water sections is probably a wave-cut scarp that is persistently present at depths of 250 to approximately 290 feet. The results ot tne deep-water reconnaissance investigation indicate that there is significant potential for beach compatible sand in water depths of 250 to 300 feet as well as dredgeable volumes within the depth of 55 to 110 and 130–240 feet within the surveyed area. The resolution of this reconnaissance survey is too coarse to specifically define borrow areas and the details of sediment textures. However, the central and southern portions of the surveyed area may include a significant volume of beach compatible sand estimated to potentially be approximately 20,000,000 cubic yards. Based on the results of the survey it is recommended that sand resources in the deep water area be evaluated in more detail using high resolution sub-bottom profiling methods in combination with coring methods applicable to deep water investigations.