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'w A S S O C I A T E S I N C In August 1995, Smith Technology conducted a subsurface site investigation to further define the extent of contamination in groundwater at the site Smith Technology supervised the installation of monitoring wells MW-4, MW-5, and MW-6 The three new wells were developed and sampled along with the original monitoring wells MW-1, MW-2, and MW-3 Analytical results of groundwater samples collected from the six monitoring wells indicated the presence of elevated concentrations of petroleum hydrocarbons in the vicinity of MW-3 and MW-6, in the northeastern corner of the site In November I998, ATC conducted a subsurface site investigation to evaluate the vertical and horizontal extent of hydrocarbon impacted soil ATC supervised the installation of three soil borings SBI, S132, and S133 from approximately 30 to 50 feet bgs Analytical results of soil samples indicated the vertical extent of soil contamination had been defined, but the horizontal extent of impacted soil was not fully identified in the northeastern corner of the site Site activities are summarized in ATC's Summary Report of Additional Subsurface Investigation, dated January 27, 1999 SAMPLING ACTIVITIES On April 14, 2003, ATC personnel collected groundwater samples from monitoring wells MW-1 through MW-6 The locations of the monitoring wells are shown on Figure 2 Prior to collection of groundwater samples, the depth to water, pH, electrical conductivity, and temperature were measured in the monitoring wells and recorded A minimum of three well casing volumes was purged from each well prior to sampling The wells were allowed to recover and samples were collected from each well using dedicated disposable bailers Purged well water was contained on site in DOT approved 55 gallon drums and labeled for disposal pending receipt of lab results The groundwater samples collected from each well were submitted to Argon Laboratories, a state-certified laboratory (FLAP cert no 2359) located in Ceres, California, for analyses Laboratory analyses consisted of total petroleum hydrocarbons quantified as gasoline (TPHg) utilizing EPA Method 8015B, benzene, toluene, ethylbenzene, total xylenes (BTEX) utilizing EPA Method 802113, and methyl tertiary butyl ether (MTBE) utilizing EPA Method 8260B Groundwater well purge and sample logs are contained in Attachment 1 ANALYTICAL RESULTS The samples from wells MW-1, MW-4, MW-5, and MW-6 contained no detectable concentrations of TPHg, BTEX, or MTBE TPHg, ethylbenzene, and total xylenes were detected in the groundwater sample collected from MW-2 at concentrations of 890, 1 4, and 10 micrograms per liter (µ/L), respectively TPHg and BTEX were detected in the groundwater sample collected from MW-3 at concentrations of 1,300 µ/L, 4 1 µ/L, 4 7 µ/L, 14 µ/L, and 16 µ/L, respectively A summary of current and historical laboratory analytical results is presented • in Table I Laboratory data sheets and chain-of-custody documentation are contained in Attachment 2 w Iwordpro1626051quartlyl2QR-2003 doc 2