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Mr Kvle Chn,tie Project 0805-114 04 May 15 1995 Page 3 Groundwater ,ampler collected from wells MW-l through MW-8 and MW-10 were analyzed for total petroleum hydrocarbons as gasoline (TPHG), and benzene, toluene, ethylbenzene and total xylene isomers using Environmental Protection Agency (EPA) Method 5030/8015 and EPA Method 5030/8020, respectively These samples were analyzed at Columbia Analytical Services, lm, , In San Jose California The results of analyses are summarized in Table 2 Copies of the laboratory analysts reports are presented in Attachment A TPHG and benzene were not detected at laboratory detection li ruts in well,,, MW-7 and MW-8 Dissolved hydrocarbons were detected In wells MW-1 through MW-6 and MW-10 TPHG concentrations ranged from below detection limits in well MW-4 to 340 parts per billion (ppb) in well MW-1 Benzene concentrations ranged from below detection limits in wells MW-2 and MW-6 to 70 ppb in well MW-5 TPHG and benzene concentrations are shown on Fiaure 2 SITE REMEDIATION After obtainiri_ an Authority to Construct Permit (Permit No N-3218-1-0) from the San Joaquin Valley Unified Air Pollution Control District, the final installation of the retnediation system was completed in September 1994, as depicted on Figure 2 The system consists of an air spargiri -enhanced vapor extraction system with cam ic. oxidation treatment (i e , AIREX TOX 100) -\s of the end of the first quarter 1995, the system utilized one air sparging well (AS-1) and 12 vapor extraction wells (VW-1 through VW-12) Once access is obtained from Asw the property owner and approval of a workplan is given by San Joaquin County Public Health Services (SJCPHS), two✓dditional air sparge wells, one additional off-site groundwater monitoring well. and two/additional vapor extraction wells will be installed at the site and will be incorporated into the System Initial start-up of the system was conducted on November 8, 1994 As of February 3 1995, the system uptime has been approximately 90 percent The 10 percent downtime was due to start-up adjustments and repair of a faulty dilution air valve that occurred during the fourth quarter 1994 Influent and effluent air samples were collected on January 23 and February 3, 1995 (see Table 3) Laboratory results indicate TPHG influent and effluent concentrations of 29 000 milk«rams Der cubic meter (rn m3) and 21,000 m T in;, respectively, on January 23 1995, and concentrations of 19,000 mg/m3 and 9,300 mg/m', respectively, on February 3, 1995 These -'e,ults indicate TPHG removal rates of 27 and 51 percent for the iespecuve . dates (see Table 4) Based on the concentrations detected and an average flow rate of W\N pyo\D80W80f 1140 4bs-45}gas 5