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<br /> ATC
<br /> A S S O C I A T E S I N C
<br /> In June and July 2000, WHF supervised the advancement of ten soil borings at the site and
<br /> completed five of the borings as groundwater monitoring wells MW5, MW6, MW8, MW9, and
<br /> MW10, and three of the borings as vapor extraction wells VE1, VE2, and VE3 Groundwater
<br /> monitoring well MW7 was replaced by vapor extraction well VE3 Soil samples collected from
<br /> borings 11101, B 103, B104, VE3, and VE 1 contained detectable concentrations of TPHg and
<br /> BTEX
<br /> SAMPLING ACTIVITIES
<br /> On August 15, 2003, groundwater samples were collected by ATC personnel from monitoring
<br /> wells MW1, MW2, MW3, MW4, MW5, MW6, MW8, MW9, and the on-site domestic well
<br /> The locations of the monitoring wells are shown on Figure 2 Prior to collection of groundwater
<br /> 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
<br /> well prior to sampling The wells were allowed to recover and samples were collected from each
<br /> well using dedicated disposable bailers After groundwater samples were collected, dissolved
<br /> oxygen was measured in each well
<br /> The groundwater samples collected from each well were submitted to Argon Laboratories Inc
<br /> . (ELAP Cert No 2359), a California-certified analytical laboratory, for chemical analysis of
<br /> TPHg and total petroleum hydrocarbons as diesel (TPHd) utilizing EPA method 8015, BTEX
<br /> utilizing EPA method 8020, and MTBE, tertiary butyl alcohol (TBA), di-isopropyl ether (DIPE),
<br /> ethyl tertiary butyl ether (ETBE), tertiary amyl methyl ether (TAME), 1,2-dichloroethane (1,2-
<br /> DCA), and 1,2 dibromoethane (EDB) utilizing EPA method 8260 Groundwater well purge and
<br /> sample logs are contained in Attachment 1
<br /> GROUNDWATER FLOW DIRECTION
<br /> Water level measurements were collected from wells MW1, MW2, MW3, MW4, MW5, MW6,
<br /> MW8, and MW9 on August 15, 2003 On August 15, 2003, water levels ranged from 71 93 to
<br /> 77 75 feet below the tops of the well casing elevations This represents a decrease in
<br /> groundwater table elevation by an average of 2 42 feet from the May 23, 2003 event On August
<br /> 16, 2003, the casing elevations were re-surveyed by Condor Earth Technologies under the
<br /> supervision of a CA licensed land surveyor The new elevations (Top of Casing, TOC Elevation)
<br /> are noted in Table 1 The water level data were used to develop the groundwater elevation
<br /> contour map (Figure 3) Assuming horizontal isotropic conditions, groundwater flow in the
<br /> uppermost aquifer beneath the site on August 15, 2003 varied across the site, but in general, the
<br /> flow was southeasterly The average hydraulic gradient was calculated to be 0 05 ft/ft or
<br /> approximately 264 ft/mile A summary of groundwater monitoring data is presented in Table 1
<br /> 5\Env iromental125291Veports�3QR-2003 doc 2
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