Wood waste remediation at sediment cleanup sites in Washington State: lessons learned after 20 years of cleanup

The timber industry in Washington State has played an important role in the state’s economic and industrial development, with mills producing pulp, paper, plywood and other timber products. The state’s waterways provided the most economical means to transport and store timber, resulting in the accumulation of harmful wood waste in or near productive littoral zones. The Washington State Department of Ecology has completed cleanup at a number of sites with significant recorded accumulations of wood waste. These include the Hylebos Waterway in Tacoma, Port Gamble Bay on the Kitsap Peninsula and the Scott Paper Mill in Fidalgo Bay, Anacortes. Throughout this process Ecology has developed methodologies for evaluating wood waste impacts to the benthic community as well as compliance with the State’s Sediment Management Standards (SMS) rule. A successful evaluation of wood waste impacts is complex but key objectives that satisfy the SMS requirements include 1) identifying past and continuing sources of wood waste 2) describing the overall nature and extent (lateral and vertical extent, percent cover) 3) characterizing chemical and biological conditions of site sediments and 4) informing and selecting among the potential range of remedial alternatives. Through the cleanup of multiple sites Ecology has refined its technical understanding of remediating wood waste such as 1) the volume and types of wood waste that is harmful to the benthic environment 2) the tools and methods that best define nature and extent and environmental impacts depending on the age and origin of the wood waste 3) how to correlate conventional chemistry results with bioassay results and 4) how to best optimize the selection of cleanup alternatives