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SUPPORTING INFORMATION FOR APPLICATION OF WASTE DISCHARGE FRENCH CAMP GRAIN ELEVATOR ' PILOT SCALE REMEDIATION PROJECT ' 1. Introduction This application seeks authorization to conduct a pilot study in an impacted aquifer at the French ' Camp Elevator in French Camp, California. The pilot study will evaluate the effectiveness of injecting zero-valent iron (ZVI) into the affected groundwater system to reduce carbon tetrachloride concentrations in the aquifer. The method of ZVI injection will utilize a hydraulic fracturing technique. The French Camp Elevator is an active grain storage and transfer facility located approximately five miles south of Stockton, California in San Joaquin County. The site encompasses roughly nine acres and includes improvements such as grain elevators, grain storage bins, storage buildings,truck scales, and an office (Figure 1). Prior to 1980, liquid fumigants containing carbon tetrachloride were stored and used at the site. The fumigant was reportedly stored in five-gallon containers and no permanent tanks were ever used to store fumigant. Evidence of groundwater impact was uncovered during an environmental site assessment conducted in 1999 by QST Environmental. Between 1999 and 2001, consultants for ContiGroup Companies, Inc. (CGI) conducted a series of investigations designed to delineate the nature and extent of contamination in the subsurface underlying the site. ContiGroup began quarterly groundwater monitoring in 2001 in response to the Monitoring and Reporting Program issued by the California Regional Water Quality Control Board—Central Valley Region(RWQCB) on 15 December 2000. Data from the first half of 2002 showed reduced groundwater concentrations in groundwater samples collected from wells MW-3B and MW-4B; samples from these wells historically had the highest reported concentrations of carbon tetrachloride and chloroform at the site. To address this change in site conditions, Haley & Aldrich — with concurrence from RWQCB — implemented a groundwater extraction pilot test program. The pilot test was designed to evaluate the efficacy utilizing groundwater extraction to remediate portions of the aquifer known to be most impacted with carbon tetrachloride and chloroform. The pilot test was recently concluded and interpretations of the test results were presented in a March 2003 report (Haley & Aldrich, 2003). Briefly, we learned that pumping even a small volume of groundwater resulted in significant concentration reductions. However, because the sustainable pumping rate from any one well is low this approach would be expected to require a large number of extraction wells to be an effective full-scale strategy. Because of physical constraints at this active commercial facility, the likely ineffectiveness of the method, and the predicted high costs, groundwater extraction is not considered to be a preferred, nor potentially effective, option for this site. R9CONTGRAMCC14Cargilffrench Camp\Waste Discharge Application\supp info 6.29-04.doc 1