Skagway Ore Peninsula Redevelopment Project

The Skagway Ore Peninsula Redevelopment Project, located in the remote town of Skagway in southeast Alaska, included demolition of existing docks and mooring structures, removal of ore loading equipment, and construction of a new dock with five new mooring dolphins. Three of the new dolphins were constructed in water over 100 feet deep.

The Greenbusch Group monitored underwater and in-air sound levels during the removal of 14-inch, 24-inch, and 36-inch diameter pipe piles with a variety of vibratory hammers. Installation of 24-inch, 36-inch, 42-inch, and 48-inch diameter pipe piles with vibratory and diesel impact hammers was also measured. Underwater sound levels were measured simultaneously at two locations, 30 feet from the pile and at a distance equal to three times the water depth at the pile location. Several of the piles were nearly 300 feet long and were driven in water approximately 150 feet deep. A total of 28 piles were monitored, and staff spent 27 days in Skagway.

With temperatures dipping to as low as -27 degrees Fahrenheit, special care was given to maintaining the minimum operating temperatures of the monitoring equipment (and monitoring staff). Because of the project’s remote location, monitoring staff would frequently need to carry the equipment approximately 1 mile to and from the site each day. Pile driving also occurred in multiple work areas each day, requiring the equipment to be portable and flexible. Monitoring equipment included custom hydrophone enclosures and cables, and recording equipment capable of simultaneous multichannel measurements. Recording equipment was able to be divided into distinct measurement systems to make single channel measurements at different locations to allow for data collection several hundred feet from the pile.