Sitka Coast Guard dock switches from steel to plastic fender piles

Pile driving for the Coast Guard's new cutter dock in Sitka will use plastic fender piles instead of steel, a change that shrinks the underwater zones where marine mammals could be disturbed and also lets the work go faster. NOAA Fisheries finalized the change Aug. 3, in an authorization good for one year.

The contractor switched from 16-inch steel to 14-to-16-inch plastic. The plastic is marginally quieter, about one decibel less at close range, which was enough to shrink the zones around the work where whales and sea lions could be harassed by the noise. It also goes in faster, 15 minutes per pile instead of 30, letting crews install up to six or eight a day rather than five, a gain in construction pace alongside the smaller noise footprint.

Most of the project is unchanged: still 60 fender piles, the same vibratory installation method, and the same shutdown and monitoring rules. The quieter piles didn't lower the estimate of how many animals could be affected, because NOAA bases that on how often the species show up in the area, not on the noise footprint.

NOAA found the work poses negligible impact to affected species, and a late-July biological opinion found no jeopardy to the endangered Western Steller sea lion or the threatened Mexico-North Pacific humpback. No public comments were received.

Whether the safeguards go far enough is contested. The Marine Mammal Commission, writing last year about related Coast Guard work in Seward, Sitka and Kodiak, called the injury thresholds regulators use "outdated," meaning the standards these approvals are measured against may understate the harm. The commission also said the Coast Guard would need to consult potentially affected Alaska Native communities. Southeast Alaska Native communities, including Sitka-area subsistence users, have an identified stake, since construction noise and access restrictions can shift the movements of the marine mammals they rely on.

The Coast Guard awarded a $50.5 million contract in 2024 for a 250-foot wharf and a 200-foot floating dock in Sitka.