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GeoHydrologic Consultants, Inc. 2.3 12-Hour Pump Test A 12-hour groundwater extraction test was performed by Park on monitoring well MW- 11 in 1999(located in the UST pit)to evaluate the site for potential groundwater extraction remediation as required by SJCEHD. Transmissivity and hydraulic conductivity values were calculated from well MW-11. The transmissivity varied from 960 gallons per day per foot(gpd/foot)to 77 pgd/foot. With an aquifer thickness estimated 15 feet,the estimated hydraulic conductivity varied from 64 gpd/ft2 to 5.13 gpd/ft. A groundwater capture zone for the extraction well was estimated at approximately 110 feet. Data from the four observations wells (MW-3, MW-4, MW-7 and MW-]0) were used to calculate transmissivity and the coefficient of storage for the aquifer at the site. The transmissivity and the coefficient of storage based upon data taken from well MW-3 (located 60 feet east from M W-11)were 352,000 gpd/foot and 0.205, respectively. The transmissivity based upon data taken from well MW-4 (located 70 feet downgradient from MW-11) was 1,056,000 gpd/foot;the coefficient of storage was not calculated due to an increase in groundwater elevations. The transmissivity based upon data taken from well MW-7 (located 95 feet downgradient from MW-11)was 105,600 gpd/foot;the coefficient of storage was not calculated due to an increase in groundwater elevations. The transmissivity and the coefficient of storage based upon data taken from well MW- 10 (located 60 feet upgradient from MW-11)were 11,733 gpd/foot and 0.0068, respectively. 2.4 Baseline Soil Assessment and Temporary Closure of Underground Storage Tanks As noted in the Third Quarter 2006 Status Report (Thrifty), Circle-K on June 8, 2006, immediately prior to temporary closure of the underground storage tanks(UST's)and lease termination,performed a baseline soil assessment, which included the drilling of three soil borings each to a depth of 45 feet below grade. Results of the soil sampling indicated concentrations of up to 452 mg/Kg TPHg, 1.97 mg/Kg benzene, and 0.128 mg/Kg MTBE. The presence of MTBE again indicated release(s)by ConocoPhillips and/or Circle-K's operations at the site. The findings are included in a Baseline Assessment Report dated June 15, 2006. 2.5 Vapor Extraction System As a result of previous site assessments in 1991, 1994, 1995, 1996, and 1999(MW-12) at Thrifty Station 172, and groundwater monitoring and sampling since June 6, 1991,a soil vapor and groundwater extraction and treatment system were started on April 26, 2001. On April 26,2001, a new Baker Furnace Thermal Oxidizer Unit was placed into operation with the hour meter reading at zero. The remediation system was connected to TOC 172 UST Removal Report Final Page 5