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S08 March 2000 <br /> AGE-NC Project No 96-0232 <br /> Page 4 of 11 <br /> AGE has been unformed that ground water near the Flag City Chevron site and below 150 feet bsg <br /> is not of beneficial use due to lugh total dissolved solids (TDS) <br /> 2 5 GROUND WATER DEPTH AND FLOW DIRECTION <br /> Review oflustorical depth to ground water maps published by the San Joaquin County Flood Control <br /> and Water Conservation District(FCD&WCD)dating back to 1971 suggests that ground water depth <br /> near the site has fluctuated between approximately 5 and 15 feet bsg, review of regional ground <br /> water elevation maps published by the FCD&WCD suggest a south-southwest ground water flow <br /> direction <br /> Based on ground water monitoring data collected at the site since July 1996, ground water flow <br /> direction has been inferred to be flowing towards the north-northeast on five occasions, towards the <br /> west-northwest on two occasions and towards the south-southwest on two occasions <br /> 26 SITE STATUS SUMMARY <br /> Based on eight ground water sampling events, MTBE-impacted ground water appears to have <br /> migrated west-southwest of the site MTBE has been detected in water samples collected from a <br /> domestic drinking water well (Rocky's Restaurant- 14659 Thornton Road) located approximately <br /> 100 feet west-southwest of the Flag City Chevron site on five occasions Therefore, AGE proposes <br /> to dnll five soil borings using CPT technology and to install five "clustered" ground water <br /> monitonng wells utilizing hollow stem auger techniques to <br /> • Delineate the vertical and horizontal extent of dissolved MTBE, <br /> • Charactenze the geological and hydro-geological framework, <br /> • Assess potential MTBE-migration pathways, and <br /> • Protect the beneficial use ground water supply <br /> 3.0. SCOPE OF WORK <br /> Based on the results of the previous investigations and UST removal activities, soil and ground water <br /> at the site has been Impacted by petroleum hydrocarbons The lateral and vertical extent of MTBE- <br /> impact must be assessed and the hydrogeologic framework modeled prior to the initiation of <br /> remediation To obtain data to model the geo-hydrological system and to delineate the vertical extent <br /> Advanced GeoEmironmental,Inc <br />