The Washington State Department of Ecology and King County are planning to dredge and dispose of contaminated material left over from years of untreated combined sewer overflows off the beach at Myrtle Edwards Park.
The contaminants include, among others, cadmium, copper, lead, mercury, silver and PCBs, according to an Ecology notice seeking comments from the public.
The plan is to dredge the material and put it on a barge that will contain a filtration system that consists of straw bails and "geotextile" materials.
The filtered water will be treated at the West Point sewage-treatment plant in Discovery Park, said Larry Altose, a spokesman for the Department of Ecology. The solid material will be disposed of at an approved upland solid-waste-disposal site, he added.
There was some thought of dumping the dredged material in an approved 300-foot-deep open-water site in Elliott Bay, Altose said. But King County officials nixed the idea because of the high level of contaminants, he added.
The open-water disposal site - which is overseen by multiple agencies - is the same location the Port of Seattle had originally planned to dump dredged material from Terminal 30, Altose said.
Terminal 30 has been used by cruise ships, but it will be dredged to make it deep enough for container ships when the cruise traffic is shifted to Terminal 91 in Interbay.
The Terminal 30 disposal plan sparked complaints from the environmental camp, but the Port of Seattle has since backed off a bit, according to a Sept. 11 press release from the agency.
The Port is now recommending that 20,000 of the 60,000 square feet of material to be dredged from T-30 be placed in an approved upland landfill. The material destined for the landfill will have the highest concentration of PCBs, according to the Port Commission.
As for the CSO dredging project off Myrtle Edwards, comments can be sent to Grant Yang, site manager, WA Department of Ecology Toxics Cleanup Program, 3190 160th Ave. S.E., Bellevue, WA 98008.
Information about the project can be found on Ecology's Web site under Denny Way CSO Site.
The comment deadline is Oct. 8, and the public is asked to refer to facility number 4455938.
Yang can be reached at 425-649-7126 or gyan461@ecy.wa.gov
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