| The General Motors (GM) Former AC Rochester Facility (site) is located within the valley of the Missouri River in Sioux City, Iowa and is bounded by a steep loess bluff to the north, commercial properties to the east, and undeveloped properties to the south and west. A Sioux City municipal drinking water wellfield is located along the Missouri River southeast of the site. GM formerly used the site to assemble and test throttle-body injection fuel systems. Chemicals of potential concern (COPC) in soil and groundwater are chlorinated volatile organic compounds (CVOCs). The current remedy includes a hydraulic capture system (HCS) and a former city supply well that is currently operating as a recovery well to protect other supply wells in the area. No active remedy is occurring in the source area. Improved operation of the HCS and confirmation of capture is crucial to reducing concentrations downgradient of the property boundary and allow operation of City Well #3 to resume supplying water to the city. Evaluation of the potential for soil VI and source area remediation are also high priorities for the site. |