USACE proposes maintenance dredging of Block Island Harbor of Refuge Federal navigation project

Photo: USACE

The US Army Corps of Engineers (USACE) New England District is proposing maintenance dredging of the Block Island Harbor of Refuge Federal Navigation Project (FNP) on Block Island, Rhode Island.

The Town of New Shoreham is the sponsor and requested that this project be maintained.

The proposed work involves maintenance dredging of portions of the 4.5-metre-deep mean lower low water (MLLW) inner harbour which is made up of an anchorage area, inner channel, and inner basin, plus 0.6 metres authorised overdepth, in the Harbor of Refuge FNP. No maintenance dredging of the FNP entrance channel will occur as a part of the proposed work.

Sediment in the western portion of the 4.5-metre inner basin has been determined to be unsuitable for open water placement and will not be dredged.

Natural shoaling processes have reduced available depths to as little as 0.3 metres in the 4.5-metre MLLW anchorage making navigation hazardous at lower stages of the tide. Maintenance dredging of approximately 38,000 cubic metres of silt and fine-grained sand from approximately 2.4 hectares of the authorised project area will restore the inner harbour portion of the FNP to authorised dimensions.

Approximately 24,000 cubic metres of sand material is proposed for placement at the previously-used, nearshore placement site off of Crescent Beach. The remaining silty material (approximately 13,700 cubic metres) will be placed at the Rhode Island Sound Disposal Site (RISDS).

A private contractor, under contract to the government, will use a mechanical dredger and scows to remove the material and then transport it for placement at the disposal sites.

Construction is expected to take between three and four months between October 1 and January 31 of the year(s) in which funds become available.

The proposed work is being coordinated with: the US Environmental Protection Agency (EPA); US Fish and Wildlife Service; National Marine Fisheries Service; Rhode Island Department of Environmental Management; Rhode Island Coastal Resources Management Council; Rhode Island Historical Preservation and Heritage Commission; Narragansett Tribal Nation; and the Town of New Shoreham.

An environmental assessment is in preparation and will be available for review upon request.

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