Middle Waterway Sediment Remediation: A Case Study

The Middle Waterway, located in Tacoma, Washington, is approximately 3,500 feet long and is typified by areas utilized for both waterway commerce and critical fish habitat. The Middle Waterway Action Committee (MWAC) has completed pre-remedial design and a remedial options analysis for cleanup of the Middle Waterway. Working under the US Environmental Protection Agency (EPA) Superfund program for the Commencement Bay Nearshore/Tideflat Superfund Site, the remediation plans approved by EPA include dredging, thin-layer capping, and natural recovery. Approximately 90,000 cubic yards of dredged material from the mouth of the waterway will be disposed of in the Blair Slip 1 nearshore confined disposal facility (CDF), together with sediments from the Hylebos Waterway, to support economic development by the Port of Tacoma. Due to listing of several fish species under the Endangered Species Act (ESA) as threatened or endangered, the remediation plans were designed to support the remediation of contaminated sediments, the protection and creation of critical habitat to support salmon recovery, and waterway commerce. The successful integration of these potentially divergent objectives has been key to support by EPA, industry, resource agencies, and public interest groups. Final design plans are expected to be approved by the summer of 2002, with remediation commencing in late 2002 or late 2003, depending on the time frame for consent decree negotiations and construction of the Blair Slip 1 CDF.