Skawgay, AK – The Skagway harbor has been a tourist destination for decades with berths for five cruise ships up to 1,000 feet in length. During the cruise season, these ships disembark nearly 10,000 visitors a day. The Municipality of Skagway forecasted an increase in future tourism and was planning to expand the harbor. Plans were halted due to the severed wind and wave activities funneled towards the waterfront by the surrounding fjords.
Expansion of the inner basin required construction of a new breakwater. The Municipality of Skagway considered various concepts before landing on an innovative partially penetrating breakwater developed by PND Engineers, Inc. (PND). The partially penetrating breakwater was composed of 20-inch diameter by half-inch-thick steel pile with flat sheet pile welded to either side designed to protect the harbor from waves in waters up to 70 feet deep. Bearing pile were driven in one piece to reduce crew exposure to the harsh conditions and decreased their time spent staged on over-water templates.
In order to properly function as a wave attenuator, the sheet sections of the combination barrier pile had to extend to a certain depth. Any misalignment by the pile driving crew made threading the sheets nearly impossible. PND designed the pile lengths to minimize the length of pipe pile imbedded in the marine sediments prior to threading the attached flat sheets. Had the importance of minimizing pile penetration prior to threading the sheets been unrecognized in the design phase, constructing the interlinking barrier pile wall would have been made much more difficult.
The breakwater has been successfully tested by a number of storm events, blocking waves and greatly improving conditions in the Skagway Small Boat Harbor. With the protection of the new breakwater, the Municipality of Skagway is free to expand the harbor. Click here to read full article.