commencement bay, south tacoma channel

SOUTH TACOMA CHANNEL OF COMMEN

The Commencement Bay, South Tacoma Channel site covers 2½ square miles in Tacoma, Washington. The site includes three Project Areas being addressed as distinct sites: the Tacoma Municipal Landfill, South Tacoma Field, and Well 12A. The background for each problem area is described below. Project Area #1: Tacoma Landfill, Pierce County, Tacoma, Washington The Tacoma Landfill covers approximately 210 acres and is operated by the City of Tacoma. In 1960, the landfill began accepting municipal, industrial, construction, demolition, and bulk wastes. About 4 million tons of refuse have been deposited at the landfill, including wastes received in the 1960s and 1970s that have since been designated as hazardous substances. The landfill is surrounded by residential development and open land, with some commercial and industrial development. At Tacoma Landfill, landfill gas contains volatile organic compounds (VOCs) including methylene chloride and toluene. Groundwater is contaminated with VOCs and heavy metals. Private residential wells and a municipal wellfield are located downgradient of the landfill. Groundwater flows to the southwest toward Leach Creek, which lies approximately one quarter mile from the landfill. EPA's Five Year Review report, issued Sept 2008, indicates protectiveness of the remedy could not be made for several reasons. (1) New, lower surface water criteria were promulgated which drive the need for more surface water monitoring at lower detection levels to use in assessing protectiveness of the older cleanup levels (vinyl chloride, 1,2-dichloroethane). (2) The City and Tacoma/Pierce County Department of Health need to verify that residences down gradient from the Landfill were not using groundwater for drinking (the issue being that early warning values for arsenic are being exceeded as state health-based criteria are becoming lower). (3) The implications of elevated arseninc on human health and the groundwater to indoor air pathway need to be evaluated. As of this writing (January 2010), the City has addressed of the issues raised in collaboration with EPA, Washington Department of Ecology, the Tacoma/Pierce County Department of Health and with assistance from the Army Corps of Engineers. In February 2009, the City requested the third and final extension of the closure date for the Landfill - which is now December 31, 2014. (Note 3 such extensions are allowed under the Consent Decree and the previous one was granted February 25, 2005 & expired December 31, 2009.) The City and the agencies are also working on (1) long term management of the Groundwater Extraction & Treatment System (GETS) and (2) the preliminary steps of final Landfill closure. Project Area #2: Well 12A, Pierce County, Tacoma, Washington Well 12A is one of 13 wells used by the city of Tacoma to meet peak summer and emergency water demands. The well was taken out of operation by the City when it was found to be contaminated, but has been operating since July 1983 with five air-stripping towers. Investigations by EPA found the source of contamination to be centered on properties owned by the Burlington Northern Railroad and the Time Oil Company. A waste oil and solvent recycler had previously operated on the properties from approximately the 1920s until the 1960s. A Groundwater Extraction and Treatment System (GETS) was installed in November 1988. Five additional GETS wells were installed in August 1993. During construction of a Soil Vapor Extraction System (SVES) in August 1993, approximately 5,000 cubic yards of waste sludge was removed and 37,000 pounds of solvent was recovered by the vapor extraction system at the time of shut down in May 1997. As of September 1998, the GETS has removed 13,428 pounds of volatile organic compounds from treated ground water. The GETS is not meeting the cleanup criteria set forth in the 1985 Record of Decision. A remedial enhancement and optimization project is being conducted to determine if the groundwater extraction and soil vapor extraction systems can be enhanced to addressed NAPL at the site or if a different treatment technology would be more appropriate. Field work for the optimization project was completed in 2002 and the resulted in recommendations to analyze the capture zone. Capture zone analysis was completed in 2005 and those data are being evaluated to improve the system. Project Area #3: South Tacoma Field, Pierce County, Tacoma, Washington The South Tacoma Field comprises 260 acres of land at the edge of an industrial area in Tacoma, Washington. Historically, the site was used by Burlington Northern Railroad for rail car manufacturing, repair and maintenance from 1892 to 1974. At that same time, iron and brass foundries operated on-site and produced various rail car parts. The swamp area of the site was used as a dump for foundry, construction and domestic wastes. In the north end, Tacoma City Light has operated since 1953 and previously stored and maintained transformers. Additionally, Tacoma Public Works has discharged city stormwater from two outfall locations on the west side of the site since 1950. In September 2008, EPA issued the 2nd Five Year Review Report for this project area. Protectiveness was not established because upgrades are needed to prevent public access to capped areas and groundwater monitoring needs to be optimized.