Chignik Public Dock
Owner: Alaska Dept. of Transportation
Lead Design Firm: PND Engineers Inc.
General Contractor: Pacific Pile & Marine LP
The remote fishing town of Chignik is only accessible by plane or boat, and without a new dock, its residents were in danger of losing their state ferry service.
To deliver the $12-million dock by spring 2016, the project team worked through one of the area’s worst winters on record, says Andy Romine, project manager at general contractor Pacific Pile & Marine. The dock’s design features 13 “open cells,” which resemble interconnected horseshoes and were built with 905 sheet piles 30 ft to 77 ft long.
Soft soil conditions complicated dock construction. Workers drove the piles using guide wire support and tiered templates to maintain plumbness and wall stability throughout installation. Each sheet had to be anchored to the template to prevent pile slippage or unwanted movement of the sheet before it was driven to grade.
The team had access to an existing stockpile of fill for the project—material dredged during the construction of Chignik’s boat harbor in 2012. But the material’s weakness presented another challenge.
“The fill material was not competent to hold up equipment. It was adequate to hold up the dock, but you couldn’t run equipment on it,” Romine says. The answer was an extra bargeload of 14,000 tons of gravel to add on top of the fill material.
The softness of the existing ground made it hard to keep the dock in alignment, Romine says, and impacted the construction process. “We had to put in a lot of the dock at one time. Usually, this dock is built in a sequence—you do a part and fill it in as you go. We had to build a lot of it and then do all the backfill at once.”
The project is a key infrastructure improvement for Chignik. Beyond getting the ferry in and out during the summer months, town officials hope the new dock will encourage economic growth in the fishing and mining industries.
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