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Ripon Farm Service - 3 _ <br /> � August 25, 2011 <br /> Remediation Summary <br /> • Free Product: No free product was documented throughout the life of this case <br /> • Soil Excavation: An unknown volume of impacted soil was removed and disposed <br /> offsite in 1987 <br /> • In-Situ Soil Remediation: Soil vapor extraction, conducted from December 2000 through <br /> December 2003, removed approximately 4,229 pounds of TPHg <br /> • Groundwater Remediation: No groundwater remediation has been conducted. <br /> General Site Conditions <br /> • Geology and Hydrogeology: The Site is underlain byiinterb4edded and intermixed sand, <br /> silt and clay. The depth to groundwater varies seasonally between 24 to 27 feet bgs and <br /> the groundwater gradient is west. i <br /> • Residual Mass Estimate in Soil: Advance Geoenvironmental (AGE) estimates that 317 <br /> pounds of TPHd remains in site soil. <br /> • Groundwater Trends: There are more than 17 yearsof groundwater monitoring data for <br /> this Site. 1,2 DCA trends are shown below, source area (MW -4) and-down gradient i <br /> (MW-9) <br /> 1,2-OICHLOROETHANE Results for MW4 <br /> 140 <br /> I I � I .► <br /> l <br /> f <br /> +nm 1.2-DICHLOROE7HANE Wena <br /> i 1.2-DICHLOROETHANE Results for MWa <br /> I. <br /> I L <br /> 0.3 <br /> E .P". .r'`t' ,, A'` .a' 4a� .rte r .4� <br /> 1.2.DICKLOROETHANE —Trend <br /> I <br /> Sensitive Receptor Survey <br /> A Sensitive Receptor Survey (SRS) was conducted in 1998 by AGE. A records search at the <br /> Department of Water Resources and an on-the-ground survey in the area identified three water <br /> supply wells within a 2,000 foot radius of the Site. One well exists 75 feet north of the site and <br /> supplies water for the Jimco Truck stop (screen interval, 160-200 feet bgs). The second well <br /> serves a residence southeast of the site. " <br /> Risk Evaluation <br /> i <br /> Soil vapor survey conducted in April 2011. Soil vapor samples were' <br /> below commercial ESLs. <br />