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•1 "1 S iG C ® Ifs . 7-Eleven Store#32262 Extended Groundwater Pumping Test and Oxygen Infection Feasibility Study November 15, 2005 Page 7 Kiff Analytical in Davis, CA for analysis of TPHg, BTEX, MtBE, TBA, DIPS, EtBE, and TAME by EPA Method 82608 Laboratory Analytical Results Laboratory analyses of groundwater samples collected before and after the pumping test are presented in Table 1 BTEX, TBA, DIPE, ETRE, and TAME were not detected in samples EX-1 Pre and EX-1 Post at concentrations above laboratory limits Maximum MtBE and TPHg concentrations in EX-1 Pre and EX-1 Past were 1,100 pg/L and 510 lag/L, respectively The groundwater sample collected from the holding tank (BT-1) did not contain concentrations of TPHg, BTEX, TBA, DIPE, and ETBE above laboratory reporting limits MtBE and TAME were detected at 880 pg/L and 2 0 pg/L, respectively Certified laboratory analytical data and chain-of-custody documentation are in Attachment D Hydrocarbon Removal and Groundwater Disposal During the groundwater pumping test approximately 3,570 gallons of groundwater was extracted from EX-1 Approximately 0 008 pounds of TPHg, 0 0 pounds of benzene, and 0 022 pound of MtBE were removed from groundwater during the test Hydrocarbon removal data is presented in Table 2 The extracted groundwater generated during the pump test was temporarily stored onsite in a 6,500 gallon holding tank and hauled by Gomez Tucking and disposed of at Instrat in Rio Vista, California Groundwater disposal documentation is presented in Attachment E OXYGEN INJECTION FEASIBILITY STUDY On August 10-12, 2005, SECOR conducted an oxygen infection feasibility test using oxygen Infection well S-1 Approximately 300 cubic feet (ft') of oxygen was infected into well S-1 (Figure 2) over 30 minutes Dissolved oxygen (DO) concentrations were measured with a DO meter equipped with a down-hole probe During the test, infection pressures and flow rates were recorded from the infection well and lower explosive limit (LEL) oxygen measurements were collected in S-1 and in adjacent wells EX-1 and MW-5 Prior to the infection test, DO concentrations in the S-1, EX-1, and MW-5 were 0 2 milligrams per liter (mg/L), 0 1 mg/L, and 0 0 1 mg/L, respectively After the infection test, DO concentrations in EX-1 and MW-5 were 0 2 mg/L and 0 1 mg/L, respectively 24 hours after infection into S-1, DO concentrations in EX-1 and MW-5 were 0 4 mg/L and 0 2 mg/L, respectively 48 hours after infection Into S-1, DO concentrations in EX-1 and MW-5 did not increase (Table 3) 17-Elevenl7-11 5tores1322621Reports132262 Pump Test and 02 Feasibility 11-10-05 doc SECOR International Incorporated t