This update was provided by the South Island Dredging Association
to the CSA Board Oct. 25, 2011.

South Beach Marina Dock, Shops and Restarurants

The South Island Dredging Association (SIDA) has begun to implement the Task Force recommendation for dredging the designated Sea Pines waterways and marinas. GEL Engineering of Charleston has been engaged to direct the permitting process and oversee the required testing program. They will be assisted by additional experts where appropriate to gather the needed data described below.

Currently, SIDA has a state dredging permit (Critical Area/Water Quality Certification Permit) and a federal dredging permit (Army Corps of Engineers). Both permits specify hydraulic dredging with disposal at the Port Royal Ocean Dredged Materials Disposal Site (the ODMDS). The separate permit for disposal at the ODMDS has expired. All of the testing to obtain a new ODMDS permit was completed but the application was put on hold when potential dredge contractors declined to bid on the project and the Task Force began its review.

The disposal method now specified in the current permits held by SIDA is not feasible. Disposal at the ODMDS is permitted only by bottom dumping barge. The insurmountable problem is that there is no bottom dumping barge that can contain the fine grain pluff mud without excessive leakage when filled via hydraulic dredging. Such leakage would result in work stoppage and potential sanctions. For this reason no contractor responded to SIDA's request for bids in 2008 for hydraulic dredging with this method of disposal.

SIDA will seek to obtain new permits so that disposal of the dredged material can be placed in designated areas of the Calibogue Sound, a method known as "inshore open water disposal." SIDA intends to use the traditional hydraulic cutterhead dredge technology which is the preferred method of regulators and the method specified in SIDA's current permits.

In its earlier applications in 1999 SIDA had sought approval of inshore open water disposal. In this regard SIDA hired experts approved by the regulators to conduct extensive testing of the material to be dredged and deposited in carefully selected sites in Calibogue Sound. The testing program was prescribed in the "Evaluation of Dredged Material Proposed for Discharge in Waters of the U.S. - Inland Testing Manual" and the work was overseen by an inter-agency task force of state and federal regulators. The tests found no level of any pollutants that exceeded permissible levels. All of the test results were within the EPA/Army Corps of Engineers acceptable parameters for each of the venues to be dredged. Nevertheless, certain of the regulators and some environmental groups advised against inland open water disposal and a protracted permitting and litigation process was anticipated. Because of the urgent need to dredge Harbour Town marina which was becoming inaccessible, SIDA amended its permit to allow disposal at the Port Royal ODMDS. The testing in 2008 confirmed the absence of elevated concentrations of pollutants in the sediment to be dredged. There is no reason to think that there has been any change in the level of any pollutant in the sediments now proposed for dredging. The regulators, of course, will insure this is confirmed as necessary.

The Corps uses open water disposal in inland and near shore locations in many locations throughout the United States. The "Inland Testing Manual" was prepared by the Corps and the Environmental Protection Agency to evaluate locations for this very purpose. There are at least two locations in South Carolina where the Corps has performed inland open water disposal in recent years. In April 2010, the Corps used open water disposal to remove a shoal in the Atlantic Intracoastal Waterway near its intersection with the North Edisto River. The Corps hydraulically dredged the material to a location in the North Edisto River between the Intracoastal Waterway and the Atlantic Ocean. The Corps also used open water disposal approximately five years ago in the Dewees Inlet, an inlet adjacent to the north end of Isle of Palms.

Both federal and state regulators would have to approve inland open water disposal. As for state regulation, the South Carolina Critical Area Permitting Regulations provide for open water disposal at R.30-12.I(2)(b):

"Open Water and deep water disposal should be considered as an alternative if highland alternatives are not feasible. However, open and deep water disposal sites should be seriously considered only after careful consultation with the Department and other relevant State and Federal agencies."

Recent meetings with state and federal regulators suggest that obtaining approval for inland open water disposal is possible if all of the requisite testing and evaluations prove satisfactory. The Corps has offered to chair and coordinate an inter-agency review of inland open water disposal for our venues and SIDA has asked that it do so. As part of the process the regulators may require that prior tests be updated and likely will also require additional testing to determine if there will be potential harm to the environment from inland open water disposal. The testing program is extensive and addresses such issues as sediment size and chemistry, essential fish habitat, benthic evaluations, bathemetry, and dispersion modeling. All of these data will be used to determine the suitability for inland open water disposal and the best locations and methods to employ.