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Top Filling Station • - 3 - • October 23, 2011 <br /> of the monitoring wells and groundwater level contours is provided at the end of this five year <br /> summary. <br /> Remediation Summary <br /> • Free Product: No free product was documented throughout the life of this case <br /> • Soil Excavation: Unknown <br /> • In-Situ Soil Remediation: Soil vapor extraction, conducted from August 2004 through <br /> unknown <br /> • Groundwater Remediation: Groundwater extraction, conducted from November 2004 <br /> through present, has removed 4,021,840 gallons of groundwater and 938 pounds of <br /> TPHg. The current rate of TPHg removal is 1.2 pounds of TPHg per day <br /> General Site Conditions <br /> • Geology and Hydrogeology: The Site is underlain by interbedded and intermixed sand, <br /> silt and clay. The depth to groundwater is approximately 36 feet bgs and the <br /> groundwater gradient is north northeast <br /> • Groundwater Trends: There are more than 16 years of groundwater monitoring data for <br /> this Site. Benzene trends are shown below, source area (MW-76) and down gradient <br /> (MW-3) <br /> BENZENE Results for MW7B <br /> wow <br /> 70ao0 j <br /> 80000 <br /> 10. <br /> .J <br /> j --eervzErve ___T,. <br /> BENZENE Results for MW3 <br /> 10000 <br /> 8000 <br /> 8000 <br /> 7000 <br /> e000 <br /> 8000 <br /> x000 <br /> —aervzerve _--HADD <br /> Risk Evaluation <br /> There are no water supply wells or surface water receptors present within 800 feet of the Site. <br /> Recommendation <br /> April 2008, the Fund recommends that the San Joaquin County LOP direct the Responsible <br /> Party to assess the effectiveness of the current remediation systems and implement other <br /> technologies to achieve Water Quality Objectives in a timely manner. The Fund will review this <br /> site next year to track progress. <br />