After years of study and debate, plans to dredge Harbour Town Yacht Basin and two other clogged waterways on Hilton Head Island are advancing.
The South Island Dredging Association, composed of boat-slip owners and some Sea Pines residents, applied Sept. 10 with the U.S. Army Corps of Engineers in Charleston for permits to hydraulically dredge creeks and marinas in Sea Pines.
Regulators, town officials and environmental groups have yet to formally weigh in. Some say they remain wary of the proposal to pump about 300,000 cubic yards of silt, clay and sand into open water near the mouth of Calibogue Sound. Doing so requires approval from state and federal regulators, who halted a 2003 effort to deepen the waterways after a contractor was accused of improperly dumping dredge spoil into the sound.
If a permit is approved, dredging would begin in November 2013 and be finished by April 2014, according to SIDA.
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Those being asked to pay for dredging -- about $4 million, one SIDA member estimates -- include Harbour Town Yacht Basin slip owners, Sea Pines Resort, South Beach and Gull Point homeowners associations, the Baynard Cove property owners association and South Beach Marina.
Material would be dredged using a small cutterhead -- a spiral-tipped device that cuts into the marina and creek bottom -- and pumped 2-3 1/2 miles along the Hilton Head shore through the pipe into open water, using booster pumps.
The dump site would be less than a mile south of the toe of Hilton Head and more than 1 1/2 miles from Daufuskie Island.
The pipe would be submerged when crossing channels to avoid boat traffic.
When completed, the dredging should improve access from Sea Pines waterways to Calibogue Sound for recreational and commercial craft.
Harbour Town Yacht Basin is only 4 1/2 to five feet deep at an average low tide, making it too shallow for large yachts and some commercial sightseeing and charter operations. It would be dredged to eight feet at average low tide.
The other dredge sites are Baynard Cove Creek and Braddock Cove Creek. Dredging would deepen the creeks and the marinas to between 5-8 feet at average low tide.
SIDA has provided nearly 500 pages of studies by a Charleston coastal engineering firm it hired that indicate the dredge material will not harm marine life or the estuary.
Reed Armstrong of the Coastal Conservation League's South Coast office seems to concur with the results of the seven studies by GEL Engineering.
The environmental group has opposed previous plans, fearing that material dumped in the sound could drift and harm water quality and marine life, including shrimp and other shellfish.
"(My) summary view is that the seven studies seem thorough and support inland waters disposal of dredge spoil at the proposed disposal location," Armstrong wrote in response to an email from The Island Packet.
He does have reservations: "But, there are a number of regulatory issues, other options and regulatory oversight and responsibilities, which need to be clarified and defined."
The spoil will be dumped on about 56 acres of sandy bottom near Barrett Shoals, where the Town of Hilton Head gets sand for beach renourishment.
According to GEL, the site is desolate, with "relatively low biological diversity" and removed from sensitive habitat.
Its models also indicate tidal currents will sweep much of sediment seaward, preventing it from accumulating on island beaches or in marshes, creeks or the nearby Cooper and May rivers.
As for federally threatened and endangered species, most are not present in the area when work would take place, according to GEL. Leatherback and loggerhead sea turtles and West Indian manatees, though, could be around.
SIDA's dredging plan calls for a full-time observer in April, when sea turtles and manatees migrate to the area. Specific provisions are to be taken if sea turtles and manatees are sighted, including shutting down operations until the creatures have left a 100-yard perimeter for at least 30 minutes.
An inspector also will ensure dredging remains within permitted boundaries and regularly survey the entire length of pipeline for damages, leaks, spills or other problems, which will be recorded and immediately repaired, according to SIDA.
Water-quality testing and habitat surveys also will be conducted before, during and after dredging, according to the application.
The Coastal Conservation League, however, wants regulatory assurances that if problems occur, an authority is assigned to stop or revise operations.
Armstrong said a bond also should be required to cover costs of potential cleanup or removal of equipment if operations are halted.
Dave Harter, president of the Hilton Head Sportfishing Club, sees little issue with the proposed work -- at first blush.
"(The disposal site) is a relatively innocuous area, especially during winter time," Harter said. "It's not a hot fishing area. It's a little desolate out there. However, it is a place to fish for tarpon, shark and lady fish during the summer. But if they went out a couple miles further, they'd encroach onto an artificial reef."
Not everyone, though, approves of the proposed work.
Judy Almand, executive director of the Port Royal Sound Foundation, said discharging "sludge" outside of Calibogue Sound is an improvement over previous plans, but still opposes the dredging.
"While the Port Royal Sound Foundation recognizes the economic need to maintain current marinas, the foundation does not support using dredging to maintain artificial canals through the salt marshes," Almand wrote in response to an Island Packet email, referring to Baynard Cove and Braddock Cove creeks.
The foundation works to protect natural marine resources, including Calibogue Sound.
RBC Heritage tournament officials have said the yacht basin helps set the tournament apart from other PGA Tour events and is invaluable to marketing the tournament and island.
SIDA member and Beaufort County Councilman Stu Rodman also worries that tourism at Harbour Town and South Beach will decline and neighboring home values drop as the waterways continue to fill.
"The large boats have stopped coming to Harbour Town and other boats sit in mud at low tide at South Beach Marina," he said. "... It's clear this needs to happen soon. I'm glad it's moving forward."
Several agencies, along with the Army Corps of Engineers, must review the dredging permit before it can be approved. Those include the S.C. Department of Health and Environmental Control, the S.C. Department of Natural Resources, U.S. Fish and Wildlife Service, National Marine Fisheries Service, South Atlantic Fishery Management Council, and the U.S. Environmental Protection Agency.
The agencies have 30 days to comment and may request a public hearing to consider the application. The public may also make such a request.
Follow reporter Tom Barton at twitter.com/EyeOnHiltonHead.