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<br /> A S S 0 C I A T E S I N C
<br /> In August 1995, Snuth Technology conducted a subsurface site investigation to further define the extent of
<br /> contamination in groundwater at the site Smith Technology supervised the installation of monitoring wells MW-
<br /> 4, MW-5,and MW-6 The three new wells were developed and sampled along with the original monitoring wells
<br /> MW-1, MW-2, and MW-3 Analytical results of groundwater samples collected from the six monitoring wells
<br /> indicated the presence of elevated concentrations of petroleum hydrocarbons m the vicinity of MW-3 and MW-6,
<br /> in the northeastern corner of the site
<br /> In November 1998, ATC conducted a subsurface site investigation to evaluate the vertical and horizontal
<br /> extent of hydrocarbon impacted soil ATC supervised the installation of three soil borings SBI, SB2, and
<br /> SB3 from approximately 30 to 50 feet bgs Analytical results of soil samples indicated the vertical extent
<br /> of soil contamination had been defined, but the horizontal extent of impacted soil was not fully identified m
<br /> the northeastern corner of the site Site activities are summarized in ATC's Summary Report of Additional
<br /> Subsurface Investigation, dated January 27, 1999
<br /> SAMPLING ACTIVITIES
<br /> On October 23, 2003, ATC personnel collected groundwater samples from monitoring wells MW-1
<br /> through MW-6 The locations of the monitoring wells are shown on Figure 2 Prior to collection of
<br /> groundwater samples, the depth to water, pH, electrical conductivity, and temperature were measured in the
<br /> monitoring wells and recorded A minimum of three well casing volumes was purged from each well prior
<br /> to sampling The wells were allowed to recover and samples were collected from each well using dedicated
<br /> . disposable bailers Purged well water was contained on site in DOT approved 55 gallon drums and labeled
<br /> for disposal pending receipt of lab results
<br /> The groundwater samples collected from each well were submitted to Argon Laboratories, a state-certified
<br /> laboratory (FLAP cert no 2359) located in Ceres, California, for analyses Laboratory analyses consisted
<br /> of total petroleum hydrocarbons quantified as gasoline (TPHg) utilizing EPA Method 8015B, benzene,
<br /> toluene, ethylbenzene, total xylenes (BTEX) utilizing EPA Method 8021B, and methyl tertiary butyl ether
<br /> (MTBE), tertiary butyl alcohol (TBA), di-isopropyl ether (DIPE), ethyl tertiary butyl ether (ETBE),
<br /> tertiary amyl methyl ether (TAME), 1,2-dichloroethane (1,2-DCA), and 1,2-dibromoethane (EDB) utilizing
<br /> EPA Method 8260B Groundwater well purge and sample logs are contained in Attachment 1
<br /> ANALYTICAL RESULTS
<br /> None of the analytes of interest were detected in the groundwater samples collected from MW-1, MW4,
<br /> MW-5, and MW-6 TPHg was detected in the groundwater sample collected from MW-2 at a
<br /> concentration of 400 nucrograms per liter (µ/L) TPHg, toluene, ethyl benzene, and total xylenes were
<br /> detected in the groundwater sample collected from MW-3 at concentrations of 890 µ/L, 11 p/L, 23 µ/L,
<br /> and 54 µ/L, respectively A summary of current and historical laboratory analytical results is presented in
<br /> Table I Hydrographs of groundwater elevations and analytical data are contained in Attachment 2
<br /> Laboratory data sheets and chain-of-custody documentation are contained m Attachment 3
<br /> GROUNDWATER FLOW DIRECTION
<br /> • Groundwater level measurements were collected from MW-1 through MW-6 on October 23, 2003
<br /> Groundwater levels ranged from 28 51 to 29 32 feet below the tops of the well casings, representing an
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