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Hylebos Dredging Begins
Release Date: 10/16/2002
Contact Information: Ken Marcy
October 16, 2002
32,000 cubic yards of contaminated sediment to be removed and treated
With oversight from the Environmental Protection Agency, the Occidental Chemical Corporation this week begins a three to four month effort to dredge and treat 32,000 cubic yards of contaminated sediments in the Hylebos Waterway in Tacoma= s Commencement Bay.
The area being dredged, known as Area 5106, lies near the mouth of the Hylebos Waterway, just off shore of the former Occidental Chemical facility (currently owned by Pioneer Chemical) on Alexander Avenue. The sediments, which are contaminated with volatile organic compounds (VOC's) and semi-volatile organic compounds, (SVOC's) will be removed with a specialty dredge known as a 'Toyo'. The slurry of contaminated sediments will then be pumped directly to an enclosed holding tank, and then to treatment tanks. The treatment process removes the VOC's and SVOC's by heating, mixing and aerating the slurry in the tanks. Treated sediments will be de- watered and stored on the Occidental property until the disposal site in the mouth of the adjacent Blair Waterway is prepared. .
Last March, the EPA issued orders to Occidental and other responsible parties requiring them to proceed with clean-up activities. The Hylebos Waterway is one of three remaining waterways in the Commencement Bay/Nearshore Tideflats site requiring cleanup under Superfund. Dredging work for the remaining reaches of the Hylebos is slated for 2003 and 2004.
"Marine life in the bay is constantly threatened by the pollutants in these sediments," said John Iani, Administrator of EPA's regional office in Seattle. "Occidental's efforts to remove these contaminants are another important step to restoring a healthy bay."
Since the late 1800's a multitude of industrial uses, including shipbuilding, oil refining and chemical manufacture and storage have caused widespread hazardous waste contamination of the soil and nearshore sediments in Commencement Bay. Many of the contaminants have harmed marine life and pose a threat to humans who consume fish and shellfish from the area.