Pile driving at a Juneau fuel dock could damage seals' hearing

Rebuilding the fuel dock at Juneau's Rock Dump Terminal would put months of pile driving noise into Gastineau Channel. Federal regulators estimate it could reach marine mammals as many as 1,660 times over the job, and that 852 of those exposures, nearly all involving harbor seals, could be loud enough to cause injury or permanent hearing loss. The counts are exposures rather than individual animals, so the same seal near the dock may account for several.

The National Marine Fisheries Service does not expect any animals to be killed or seriously hurt, and says most will simply move away while the work is going on. Steller sea lions, harbor porpoises, killer whales and humpbacks make up the rest of the estimate, with six exposures in the injury category between them.

There is a standard way to quiet pile driving. A bubble curtain, a ring of rising air that dampens sound underwater, is used on projects like this one. PetroMarine Services is not proposing one here, telling regulators it would be impractical economically and technically.

What it does propose is procedural: starting each pile softly before ramping up, halting work when an animal enters a set zone, and keeping at least two trained observers watching the water whenever pile driving is underway.

The job itself involves pulling 50 timber piles, driving 14 steel ones for the structures boats tie against, rebuilding the T-dock and fuel float, and armoring the slope against erosion. It would run about 81 days beginning in January 2027.

Regulators note the site is not in or near critical habitat, the nearest Steller sea lion haulout is 45 kilometers off, and the state classifies the area as non-subsistence. In a separate Juneau consultation, the Douglas Indian Association said it did not see effects on its subsistence use. Several other Juneau-area docks, including the Aak'w Landing cruise terminal and the Auke Bay ferry terminal, have received similar authorizations.

Public comment runs 30 days from the proposal's publication this week.