The East Multnomah County (EMC) Groundwater Contamination Area covers a three (3) square mile area within the cities of Gresham and Fairview, Oregon. The area extends from N.E. Halsey Blvd. to the Columbia River, and from N.E. 178th Ave. to N.E. 223rd Avenue.

Two aquifers within the project area are contaminated with trichloroethene (TCE), an industrial solvent. The groundwater contamination covers a 400 acre area centrally located within the project area. The contamination was caused by land disposal of used solvents at the Cascade Corporation and Boeing of Portland facilities during the 1960s. At the time, it was thought that the solvents would
completely volatilize; instead, the solvents seeped into the groundwater.

Eight of the City of Portland's South Shore wellfield supply wells are located within the project area and downgradient of the area of contamination. The wellfield serves as a backup source of drinking water for the city. A number of other domestic and municipal water supply wells are also located within the project area and are threatened. None of the City's wells have been impacted to date.

In May 1993, EPA proposed to place EMC on the National Priorities List (NPL). This would designate EMC as a federal "Superfund" site. In September 1995, DEQ requested that EPA defer final listing of the site.

DEQ issued a remedial action record of decision (ROD) for the area-wide contamination in the deeper TSA aquifer on December 31, 1996. The cleanup for the TSA aquifer includes the installation of up to 23 groundwater extraction wells and treatment using air stripping technology. The cleanup is projected to cost Boeing and Cascade $10 to $12 million and take approximately 20 years to complete. DEQ issued a consent order to Boeing and Cascade on February 14, 1997 which specifies the requirements, deliverables and schedule for implementing the final remedy selected by DEQ.

Quarterly Activities

Construction of the air stripper located on Boeing property north of Sandy Blvd. was completed in late August 1997, and groundwater extraction was initiated from four extraction wells north of Sandy Blvd. on September 12. As of September 15, 11 extraction wells are operational and extracting contaminated groundwater at a rate of approximately 500 gallons per minute (gpm).

Decommissioning of two private supply wells owned by Sandy Mobile Villa was completed in early August 1997. Hookup of three private residences to the City of Fairview public supply system was also completed.

Two monitoring wells were installed into the deep Sand and Gravel aquifer (SGA). One well is northeast and the other south of the area of SGA contamination. No contamination was detected in either well, indicating the extent of the problem appears to be limited. An interim assessment report was issued on October 1, 1997 which illustrates predicted migration of SGA contamination under PWB pumping scenarios.

An additional six to seven extraction wells are projected to be drilled and brought on-line in the next 3-6 months.

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