Sinkhole found under Ketchikan harbor shop as council adds $151,000 for storm repairs

Crews demolishing Ketchikan's old harbor maintenance shop after last month's storm found a sinkhole beneath it about 20 by 12 by 6 feet, city officials told the City Council on Thursday. The council voted 7-0 the same night to add up to $150,999 to finish repairing the failed storm drain there.

City Manager Abner Hoag said a staff member believes a floor support that happened to sit right at the edge is the only reason the building didn't collapse into the hole. The shop held paint, fuel and other hazardous maintenance materials, plus a big diesel heating tank, and staff had moved all of it out.

"We were super fortunate that we took the action that we did," Hoag said.

The Oct. 15 storm collapsed the 48-inch pipe that carries stormwater from a state culvert under Tongass Avenue past the Port and Harbors maintenance building to the water, according to a city memo. Water washed out the ground behind the building, and part of the bank behind it fell into the ocean, Assistant City Manager Shawn Hart said Thursday.

P&T Construction got a contract for up to $99,000 after the storm to divert the stormwater and keep the erosion from getting worse. Thursday's amendment brings the contract to $249,999 so the company can replace the broken drain out to Tongass Narrows, the channel along the waterfront. The new 60-inch pipe is in town, waiting for better weather, Hart said. In the meantime, a relief pipe is in, and a temporary berm on Tongass Avenue is meant to send backed-up water through it toward the North Boat Launch instead of flooding the road.

The contract also covers two more damaged sites found since the council last heard about the storm Oct. 19. On Fifth Avenue near the Armory, erosion undercut trees that could have fallen. Crews took the trees down, temporarily stabilized the slope and put in a new manhole and 50 feet of pipe, and that work is about 80% done, Hart said. Just below the telecommunications building, washed-out ground needs to be backfilled. That work hasn't started.

The city has spent about $80,000 on the storm drain sites so far, and Hart estimated $400,000 to $500,000 to complete them. City officials said the work falls under the disaster declaration and is eligible for state reimbursement. The city's early damage estimate topped $4 million in October.

The biggest single repair is at Ward Cove, where the storm's landslide pushed buildings at a Ketchikan Public Utilities substation almost 8 feet off their foundations. "No customers lost power due to this," Hart said. Crews shifted those customers to other substations, and a mobile substation went into service next to the site Oct. 30. A camera is watching the slope for movement.

Repairs there could cost up to $1.5 million and take two to three months, Hart said. The city is still working out its insurance claim, and the state will cover whatever insurance doesn't, he said.