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i <br /> 1 <br /> Mary L Gardella 1991 Trust - 3 - " August 29, 2011 <br /> • In-Situ Soil Remediation: Soil vapor extraction, conducted from November 2004 through <br /> June 2005 removed approximately 2,375 pounds of TPHg y <br /> Groundwater Remediation: Ozone sparging, conducted December 2004 through <br /> June 2005, February 2006 through July 2006 and March 2011 through June 2011 <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 33 feet bgs and the <br /> groundwater gradient is southeast <br /> • Groundwater Trends: There are more than 12 years of groundwater monitoring data for <br /> this Site. Benzene trends are shown below, source area (MW-2) and down gradient I <br /> ti <br /> (MW-8) 4 `, <br /> " BENZENE Results for MW2 <br /> 5000 <br /> 4500 <br /> AI <br /> �.... .._ <br /> ,moo S50D E � <br /> z�o ._ <br /> 1500 <br /> 1000 <br /> �o <br /> BENZENE Trentl I V <br /> BENZENE Results for MW8 <br /> X11 j <br /> 06 <br /> 9.10 <br /> Risk Evaluation <br /> Soil vapor survey and human health risk assessment approved by SJC LOP by letter on <br /> 1111012009. There are no water supply wells or surface water receptors present within 900 feet <br /> of the Site. <br /> Recommendation <br /> In May 2008, the San Joaquin County LOP has directed the Responsible Party to expand the <br /> ozone sparging system. The Fund concurs with the expansion of the groundwater treatment <br /> system. The Fund will review this site next year to track progress. <br /> UPDATED, September 2010, this site has been under investigation for 17 years. The Fund <br /> concurs with the San Joaquin County LOP that a soil vapor survey and Human Health Risk <br /> Assessment should be conducted. <br /> 7 <br /> ' i <br />