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ecnics nc.Geofogicaf ThI � EE <br /> 2741 T fiver Road w' ���i� i � PI'l 12. <br /> Nodesto,Cafifomia 95351 - <br /> (209)S38-6424f°Fax,#538-5852 <br /> 'June 8, 2001 . - <br /> Project No.: 750.3 <br /> Project Name: City of Escalon <br /> Ms Linda Sanborn 4 <br /> State Water Resources Control Board "A <br /> 2014 T Street, Suite 130 • ,., w ;, 1* ti :� <br /> s <br /> P.O. Box 944212 <br /> Sacramento, CA 94244-2120 <br /> RE: Cost Pre-Approval: Vadose Zone Remediation & Groundwater Monitoring <br /> Location: Former Arco Gas Mini Mart, 1305 Escalon Avenue, Escalon, CA <br /> USTCFP:- Claim No. 013929 .W - <br /> Dear Ms Sanborn: <br /> GTI has prepared the enclosed Remedial Design Plan and a budget to perform the vadose zone <br /> remediation, plus groundwater.monitoring for a period of one year. <br /> The goal of the Remedial Design Plan is to protect public health by: <br /> • Removing the contaminants in the vadose zone that are leaching into the drinking water <br /> aquifer. <br /> • Help mitigate the BTEX plume in the groundwater by increasing the oxygen content of the <br /> capillary fringe, thus improving the natural attenuation process. <br /> • Prevent these contaminants from impacting water wells. <br /> Summar} of Work Performed <br /> GTI performed a vapor extraction pilot test at the site in`June of 2000. Field and laboratory test <br /> results showed that the site is conducive to remediation by vapor extraction. The vapor <br /> extraction wells installed for the pilot tests are adequate for the remedial action ..project <br /> proposed here. <br /> Work performed to date is summarized below: <br /> • February 1999 - six boreholes were _drilled, soil and groundwater samples collected <br /> -(including one groundwater sample from each borehole via hydropunch methods), samples <br /> tested for petroleum hydrocarbons. Analytical results show the presence of BTEX, TPH-G <br /> and oxygenated fuel compounds in the soil and groundwater. <br /> 41 <br /> April 1999 - One monitoring well and two vapor extraction wells were installed. <br /> + June 1999 - One monitoring well was installed. <br /> • ..July 1999 -.One monitoring well and two vapor extraction wells were installed. <br /> • April 2000 - A groundwater monitoring event reveals that MW-I was impacted with BTEX, <br /> TPH-G and MTBE.- Groundwater depth was approximately 56 feet below ground surface <br /> and flows to the west-northwest. <br />