Nantucket commission continues town dredging plan — consultants outline volumes, timing and protections

Consultants for the town told the Nantucket Conservation Commission on April 16 that a proposed maintenance dredging project would restore navigation in two shallow harbor channels, but the commission continued the filing to its May 7 meeting to allow state reviews and sediment characterization to be provided.

Doug Partridge of Arcadis and Ben Smarfy of the town's natural resources department described two work sites — in and near the harbor entrance and in Heather Creek — and said the work is intended to restore recreational and commercial boat access and protect public ramps, moorings and shellfish areas. "The whole purpose and sole purpose here is for his main purposes, but 1 of the major purposes is for navigation," Partridge said during his presentation.

Partridge gave design details for the proposed footprints and elevations and estimated dredge volumes under different scenarios. He said the dredging would be performed to a design elevation of −7.35 NAVD88 with a 2‑foot allowable overdredge; with that overdredge the larger site could total as much as about 51,000 cubic yards, while more conservative excavation would be closer to 15,000 cubic yards. He said the town expects two dredging events at the smaller site over a 10‑year period and more frequent maintenance at the larger creek site, which his modeling indicated could require multiple passes per year.

On environmental protections, Partridge said the work window would run from Oct. 3 to Jan. 15 to avoid state‑ and federally regulated species impacts, and that remote sensing and acoustic mapping showed eelgrass was largely absent from the proposed footprints. He also said the team has met with state reviewers including MEPA and has submitted a MISA form and expects to receive responses in short order.

Commissioners pressed the consultants on where dredged material would be staged and how it would be handled. Partridge said dredged material would be barged to upland sites for temporary dewatering and trucked offsite; he added that no beneficial‑reuse projects have yet been formalized. "Right now, we have no beneficial, reuse projects that have been identified or approved," he said.

Because agency responses and sediment sampling remain outstanding, the commission agreed to continue the town's Notice of Intent to the May 7 meeting so staff can provide state feedback and the applicants can submit required sampling and permit coordination materials.

The commission did not vote on the project scope or issue permits at the April 16 meeting; the continued hearing is scheduled for May 7.