The 83-acre Pacific Sound Resources (PSR) site, formerly known as the Wyckoff West Seattle Wood Treating facility, is located on the south shore of Elliott Bay on Puget Sound in Seattle, Washington. A wood-treating facility operated at the site between 1909 and 1994. Wood-preserving operations used creosote, pentachlorophenol (PCP) and various metal-based solutions of copper, arsenic and zinc. Daily operations, as well as spills, leaks and storage of treated wood products resulted in soil and groundwater contamination. Direct discharge or disposal of process wastes and indirect transport were the most likely sources of contamination to the marine sediment. Following cleanup, operation and maintenance activities and monitoring are ongoing.