NSF-led offshore drilling near Nantucket draws public questions on permits, discharges and aquifer links

A team from the National Science Foundation and the International Ocean Drilling Program told the Nantucket Select Board it plans a summer expedition to core sediments and sample groundwater at three sites south and southwest of the island to study a subsea freshwater lens.

The researchers said the project proposes two boreholes at each of three sites — about 20, 27 and 43 miles from Nantucket — with coring to as much as 550 meters below the seafloor. Two boreholes would receive vertically deployed sensor cables left on the seabed for data collection, potentially for up to two years, the team said.

The expedition team emphasized its scientific goals: to determine how, when and whether meteoric (rainfall-derived) or glacial meltwater entered shelf sediments and how long that freshwater has persisted. “We're trying to understand how and when this freshwater was in place in sediments beneath the ocean,” said Brandon Dugan, identified as a hydrogeologist and professor at Colorado School of Mines.

Why it matters: Nantucket relies on a shallow sole-source aquifer for municipal water. Residents at the meeting asked whether the…