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1 <br />' Site Background Information West Clay Properties <br /> Page 3 of 6 <br /> California Based on the low to non-detect concentrations of petroleum hydrocarbons in the soil <br />' samples collected from the sidewalls and floor of the excavation, it appears that the major portion <br /> Of the most significantly impacted soil was removed during over-excavation <br />' Ground Water Monitoring- Based on analytical results of ground water samples collected during <br /> quarterly monitoring and site assessment activities, the most impacted ground water appears to be <br /> centered around EW-1 and MW-10 The vertical extent of the contamination plume, as well as the <br />' lateral extent east and south of the former UST cluster, is not well defined <br />' CPT INVESTIGATION <br /> Between 01 and 04 June 2004,four CPT soil borings(CPT-01 through CPT-04)and 11 individually <br />' established soil borings for collection of ground water samples were advanced at the southern UST <br /> No 3 location and the northern UST cluster area CPT soil borings were advanced at the following <br />' locations- ground water samples were collected from dedicated borings at the following intervals <br /> • CPT-01, CPT-02 and associated ground water sampling borings were advanced near the <br />'• northern boundary of the former UST No 3 location (Figures 2 and 3) to determine the <br /> vertical extent of petroleum hydrocarbon-impacted ground water CPT-01 and CPT-02 were <br /> co-located borings CPT-01 was advanced to approximately 100 feet bsg, CPT-02 was <br /> advanced to approximately 170 feet bsg-CPT-01 was sampled between 77 and 81 feet bsg <br /> and between 93 5 and 97 5 feet bsg while later CPT-02 was sampled between 114 and 118 <br /> feet bsg and between 137 and 141 feet bsg, <br /> I • CPT-03 and associated ground water sampling borings were advanced south-southwest of <br /> the former UST No 3 location to determine the down-gradient extent of petroleum <br /> hydrocarbon-impacted ground water CPT-03 was advanced to approximately 210 feet bsg <br /> -CPT-03 was sampled between 50 and 54 feet bsg, 74 and 78 feet bsg, 133 and 137 feet bsg <br /> and 176 and 180 feet bsg, <br />' • CPT-04 and associated ground water sampling borings were advanced north of the former <br /> UST cluster excavation (Figures 2 and 4) to determine the vertical extent of petroleum <br /> hydrocarbon-impacted ground water at the former UST cluster area CPT-03 was advanced <br /> to approximately 175 feet bsg <br /> • Ground water sampling boring CHB-01 was advanced approximately 70 feet east-northeast <br /> of CPT-04 to determine the vertical extent of petroleum hydrocarbon-impacted groundwater <br /> down-gradient of the former UST cluster area-CPT-04 was sampled between 80 and 84 feet <br /> bsg and 166 and 170 feet bsg, while - soil boring CHB-01 was sampled between 78 and 82 <br /> Ifeet bsg <br /> • <br /> Advanced GeoEnvironmental,Inc <br />