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t i ATC Associates Inc. 1117 Lone Palm Avenue, Suite B Modesto,California 95351 209-579-2221 ASS%TC O C I ATE S I N c. Fax: 209-579-2225 Groundwater samples were collected from monitoring wells MW-1 through MW-8. Prior to collection of groundwater samples a minimum of three well casing volumes were purged from each well. The pH, electrical conductivity, and temperature were measured and allowed to stabilize before groundwater samples were collected. Samples were then collected from each well using disposable bailers. Purge water was contained in 55-gallon DOT approved drums. Groundwater well purge and sample logs are provided in Attachment 1. The groundwater samples collected from each well were submitted with Chain-of-Custody Record to State-certified Argon Laboratories Inc. (Environmental Laboratory Accreditation Program Certification No. 2359). The samples were analyzed for TPHg by EPA Method 8015M; BTEX by EPA Method 8021B; and MTBE, tert-amyl methyl ether (TAME), TBA, di-isopropyl ether (DIPE), ethyl-tert-butyl ether (ETRE), 1,2-dichloroethane (1,2-DCA), and 1,2- dibromoethane(EDB)by EPA Method 8260B. LABORATORY ANALYTICAL RESULTS TPHg was detected in the groundwater sample collected from MW-2 and MW-4 at a concentration of 330 micrograms per liter (µg/1) and 80 µg/1, respectively. Benzene was detected in the groundwater samples collected from MW-2, MW-3, and MW-4 at concentrations of 200 µg11, Il µg/1, and 3.3 µg11, respectively. Toluene was detected in the groundwater sample collected from MW-2 at a concentration of 0.7 µg/l. Ethyl benzene was detected in the groundwater samples collected from MW-2, MW-3, and MW-4 at concentrations of 4.2 µg/1, 2.5 µg/l, and 5.3 µg11, respectively. Xylenes were detected in the groundwater samples collected from MW-2 at a concentration of 6.0 µg/1. MTBE was detected in the groundwater samples collected from MW-1, MW-2, MW-3, and MW-4 at concentrations of 1.8 µg/1, 15 µg/1, 2.9 µg/1, 1.6 µg/l, respectively. The laboratory analytical results indicate constituents of concern (COCs) were detected in the groundwater samples collected from MW-1, MW-2, MW-3, and MW-4. Only the groundwater samples collected from wells MW-2 MW-3 and MW-4 contained benzene at concentrations that exceeded the Maximum Contaminant Level (MCL) of 1.0 µg/1. MTBE was detected in the groundwater samples collected from wells MW-1, MW-2, MW-3, and MW-4. Only the groundwater sample collected from well MW-2 contained MTBE at a concentration that exceeded the Secondary MCL of 5.0 µg/1. Groundwater analytical results are summarized in Table 2. The laboratory analytical reports are included in Attachment 2. sAEnviromnentahl78611reportsl4gmr2005.doc 4 ATC Associates Inc.