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NPL Site Narrative for Seattle Municipal Landfill (Kent Highlands)

Kent, Washington

Federal Register Notice:  August 30, 1990

Conditions at proposal (June 24, 1988): Seattle Municipal Landfill (Kent Highlands) is in Kent, King County, Washington, approximately 14 miles south of Seattle. From June 1968 to December 1986, Seattle filled about 60 acres of a 90-acre ravine on a hillside above the Green River. Seattle leased the site from Kentview Properties, Inc., and operated it under a "Nonconforming Permit" from the Seattle-King County Department of Public Health.

In addition to municipal wastes from Kent and Seattle, the landfill accepted sand-blasting grit, some industrial sludges, and other industrial wastes, according to Health Department records.

In 1984, a consultant to the county detected zinc, copper, barium, and manganese in on-site monitoring wells. Over 18,000 people obtain drinking water from public wells within 3 miles of the site, the nearest within 1 mile.

Leachate seeps on the east side of the landfill mix with run-off from the landfill, which is routed through drainage lines to settling ponds that eventually discharge to the Green River. The river is used for spawning and rearing salmon.

In 1985, a consultant to Seattle detected 1,2-dichloroethane and tetrachloroethylene in the air at the edge of the site. An estimated 12,700 people live within 1 mile of the site.

Seattle is currently closing the landfill and developing plans to meet all local, State, and Federal requirements. Under a Consent Agreement signed with the State in May 1987, Seattle is conducting a remedial investigation/feasibility study (RI/FS) to determine the type and extent of contamination at the site and identify alternatives for remedial action. The work is scheduled to be completed in April 1989.

Status (August 30, 1990): The original RI has been completed. Additional data needs resulted in a Phase II RI, which is scheduled to be completed in June 1991. The FS is scheduled to be completed in December 1991. An interim system has been installed in an effort to prevent landfill gas from concentrating on-site or migrating off-site.

For more information about the hazardous substances identified in this narrative summary, including general information regarding the effects of exposure to these substances on human health, please see the Agency for Toxic Substances and Disease Registry (ATSDR) ToxFAQs. ATSDR ToxFAQs can be found on the Internet at ATSDR - ToxFAQs (http://www.atsdr.cdc.gov/toxfaqs/index.asp) or by telephone at 1-888-42-ATSDR or 1-888-422-8737.

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