Searching for fresh, cheap sand in Stono Inlet
By Warren Cobb | Managing Editor
In July, Folly Beach City Council voted to pay $67,517 from the Beach Preservation Fund to Athena Technologies LLC for Vibracore Sampling in the Stono Inlet. Vibracore sampling involves drilling into the seafloor and pulling a sample out for study. Cores collected are analyzed for chemical evaluation of sediment for pre-dredge, site assessment, monitoring, or remediation planning purposes.
The City is in the middle of a Limited Reevaluation Report with the Army Corps. The purpose of the report is to find new sand for Folly Beach’s future renourishments, ideally between eight and ten million cubic yards. “Working this far in advance allows us to find the best sand at the lowest cost and have the use of that sand permitted by other state and federal agencies like Fish and Wildlife and Department of Natural Resources,” says Spencer Wetmore, assistant to Folly Mayor Tim Goodwin, and the project liaison. “Factors that affect the cost of sand include the distance from the beach (pumping distance), the amount of sand in one place (which prevents high mobilization costs to move the dredge during pumping), and the administrative cost of having that sand approved for use.”
The Army Corps and the City have worked together to look at old studies and current geological formations to identify areas where there is likely to be sand. Several potential areas have been identified. The next step is to take samples to determine quality and quantity of sand in each place. Quality refers to whether each area actually contains sand, or if it has too much unsuitable material like mud or rocks. Quantity is how much sand is in a particular area and how far down the good sand extends. The Corps has hired Athena Technologies Inc. to take samples from areas identified by the City.
Wetmore says the sand the City believes will be the best quality and least expensive sand is located in the areas near the Stono Inlet, which is designated as a Coastal Barrier Resources Act zone (CBRA, which engineers pronounce “Cobra”). CBRA zones are places where the federal government is prohibited from spending money in certain environmentally sensitive areas under the Coastal Barrier Resources Act.
Wetmore says the act is primarily targeted at things like preventing the federal government from spending money on federal flood insurance that would encourage development in these areas. “We believe there is a large amount of high quality sand in this area and that we can work with federal and state environmental agencies to use it in an environmentally responsible way,” she says. “Even factoring in administrative costs, we believe that using this sand would be millions of dollars cheaper than using sand from offshore or farther away from the beach.”
Because of CBRA restrictions, the City can spend money on the sampling, but the Corps cannot. The City is working with the same contractor used by the Corps, which saves a tremendous amount on mobilization costs because the boat is already in the region taking the same kind of samples.
The goal is to use this sampling data to seek a public interest exemption from the CBRA restrictions that would allow the City to take sand from this area to maintain Folly Beach. “We have had the exemption before, and we want to show that we can dredge the sand responsibly and protect sensitive areas like Bird Key while maintaining our beach and all of the habitats that it provides for species like endangered birds and turtles,” says Wetmore. “Plus, it seems unreasonable for the federal government to maintain jetties (protecting the entrance to the Charleston Harbor) that block the sand from the north and then also enforce restrictions that keep us from getting sand from the south. The bottom line is that we believe that spending this money now will lead to major savings on the next renourishment projects.”
Athena Technologies LLC is slated to perform this sampling in the Stono Inlet later this year.