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City of Ripon Well#12 - Nitrate Study Report May 31,2006 3.0 INFORMATION REGARDING SURROUNDING SITES The second task that SGI carried out was to gather environmental, geological, and other background information regarding the area surrounding Well 12. One of the sites identified was the RFS site. Sources of the information were the City, the CRWQCB, and RFS. 3.1 Files from the City of Ripon SGI obtained a number of files from the City of Ripon. The documents received included correspondence, maps, and reports. SGI used these documents to help determine sites of interest other than the RFS site. Another possible site of interest, the Jimco Truck Stop, was identified from these documents. The Jimco Truck Stop is located immediately adjacent to the RFS site to the north. 3.2 CRWQCB File Review On August 3, 2005, an SGI geologist visited the CRWQCB to obtain files for the RFS site and the Jimco Truck Stop. Several files from the RFS site were viewed and copied. 3.2.1 Information obtained from the RFS Files The RFS site has operated as a fertilizer storage formation plant for approximately 45 years. Underground storage tanks (USTs) were used at the site in the past. These USTs were removed on July 15, 1987. Soil samples collected beneath these USTs indicated residual petroleum hydrocarbon contamination. Eight borings were advanced and three were converted to monitoring wells. In 1995, five additional borings were advanced and two were converted to monitoring wells. More borings and wells have been drilled, as recently as 2005. Another site with USTs, the Jimco Truck Stop, is located directly to the north of RFS. Quarterly sampling at RFS site indicate TPHg, TPHd, benzene, and 1,2-dichloroethane (1,2-DCA) in groundwater and in soil vapor. It is hypothesized in the most recent quarterly report that elevated concentrations correlate to higher groundwater levels than when the release occurred. In December 2000, a soil vapor extraction system (SVE) began operation. Approximately 748 gallons of petroleum product were removed by the system over the period of startup to December 2003. At this time, concentrations had decreased to the point that it was no longer cost effective to continue, and the system was taken offline. The most recent groundwater monitoring and well installation event at the time of the file review occurred in April 2005. At that time, RFS had already received a letter from James Barton of the CRWQCB expressing concerns about the nitrate contamination in Well 12 and City Well #5. Despite issuance of R4 Wel 12RM Gtt 3-1 the Source`41111i op,Inc.