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1 ' Site Background Information Flame Mini-Mart Page 2 of 4 1 • March 1998- Four soil borings (B 1 through B4) were advanced to maximum depths of 25 ' feet below surface grade (bsg) near the three former 10,000-gallon USTs and former fuel dispenser island areas TPH-g and BTEX compounds were not detected in any of the analyzed samples, however,MTBE was detected from soil boring BI at 20 feet bsg near the tnortheast end of the former USTs at a concentration of 0 25 milligrams per kilogram A letter of findings (Analytical Results of Pre-removal Assessment, dated 25 March 1998) was submitted by AGE to the SJCEHD ' 0 September 1999 - Three soil borings (P-1 through P-3)were advanced to maximum depths of approximately 60 feet bsg near the former UST and fuel dispenser island areas TPH-g was detected in the 50-foot soil sample from P-1 at a concentration of 2 6 mg/kg, low concentrations of BTEX compounds were detected from P-1 between 45 feet and 5 5 feet bsg at concentrations as high as 0 16 mg/kg Significant MTBE was detected from P-1 at depths ' between 25 feet and 55 feet and from P-2 at 25 feet bsg at concentrations as high as 38 mg/kg (P1-25) Laboratory analysis of a grab water sample collected from P-1 detected TPH-g at 1,500 micrograms per liter(µg/1),BTEX compounds as high as 690 gg/l benzene and MTBE ' at 420 µg/l A report of findings (Preliminary Investigation &Evaluation Report, dated 30 October 2000) was submitted by AGE to the SJCEHD ' November 1999-Ground water monitoring wells MW-I through MW-4 were installed at the site to depths of 65 feet bsg TPH-g was detected in the 45-foot soil sample from MW-2 at a concentration of 3 1 mg/kg, low concentrations of BTEX compounds were detected at 45 ' feet bsg from MW-1 and MW-2 at concentrations as high as 0 82 mg/kg Significant MTBE was detected from MW-3 at depths of 15 feet and 20 feet bsg at concentrations of 8 5 mg/kg and 11 mg/kg, respectively, MTBE was detected in the 45-foot soil sample from MW-2 at ' a concentration of 0 1 mg/kg Laboratory analysis of initial water samples collected from MW-1 through MW-4 detected TPH-g as high as 1,400 µg/l (MW-3),BTEX compounds as high as 190 µg/1 and MTBE as high as 95 µg/l (MW-2) A report of findings (Preliminary ' Investigation &Evaluation Report, dated 30 October 2000) was submitted by AGE to the SJCEHD • November 2001 -AGE advanced four cone penetrometer testing(CPT) soil borings(CPT-1 through CPT-4)to depths of approximately 100 feet bsg on-and off-site to assess the vertical extent of petroleum-impact and identify potential hydrologic units Based on CPT data,AGE ' interpreted the CPT data to identify seven potential hydrogeologic units informally identified as HUI between 55 and 63 feet bsg,HU2 between 63 and 68 feet bsg,HU3 between 68 and 75 feet bsg, HU4 between 75 and 78 feet bsg, HUS between 78 and 90 feet bsg, HU6 between 90 and 95 feet bsg and HU7 located at depths greater than 95 feet bsg Laboratory analysis of grab water samples detected MTBE from CPT-1 at depths of 60 feet and 76 feet bsg at concentrations of 88 µg/1 and 1 6 µg11, respectively, from CPT-2 at depths of 76 feet, 80 feet and 100 feet at concentrations as high as 49µg/1,and from CPT-3 at depths of 68 feet and 100 feet bsg at concentrations of 37 µg/1 and 4 3 µg/l, respectively MTBE was not detected in water samples collected from CPT-4 (Table 1) A report of findings (Cone Advanced GeoEnvironmental,Inc I