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CVATC
<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 bonngs 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 B101, B103, B104, VE3, and VE 1 contained detectable concentrations of TPHg and
<br /> BTEX
<br /> On August 16, 2003, the well casing elevations were re-surveyed by Condor Earth Technologies
<br /> for elevation to within 0 01 foot under the supervision of a California licensed land surveyor and
<br /> presented in Table 3
<br /> SAMPLING ACTIVITIES
<br /> On February 5, 2004, 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 /> Well MW10 has an obstruction at approximately 20 feet bgs and was not sampled The locations
<br /> of the monitoring wells are shown on Figure 2 Prior to collection of groundwater samples, the
<br /> depth to water, pH, electrical conductivity, and temperature were measured in groundwater
<br /> purged from the monitoring wells and recorded A minimum of three well casing volumes was
<br /> purged from each well prior to sampling The wells were allowed to recover and samples were
<br /> icollected from each well using dedicated disposable bailers
<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 8015B, BTEX
<br /> utilizing EPA method 802113, and MTBE, tertiary butyl alcohol (TBA), di-isopropyl ether
<br /> (DIPS), ethyl tertiary butyl ether (ETBE), tertiary amyl methyl ether (TAME), 1,2-dichloroethane
<br /> (1,2-DCA), and 1,2 dibromoethane (EDB) utilizing EPA method 8260B Groundwater well
<br /> purge and sample logs are contained in Attachment 1
<br /> GROUNDWATER FLOW DIRECTION
<br /> Water level measurements collected from wells MViWI, MW2, MW3, MW4, MW5, MW6, MW8,
<br /> and MW9 on February 5, 2004, ranged from 70 35 to 74 20 feet below the tops of the well casing
<br /> elevations This represents an increase in groundwater table elevation by an average of 0 76 feet
<br /> from the November 20, 2003, sampling event The data from MW6 was not used for flow
<br /> directions because it is screened in a deeper interval The water level data were used to develop
<br /> the groundwater elevation contour map (Figure 3) Assuming horizontal isotropic conditions,
<br /> groundwater flow in the uppermost aquifer beneath the site on February 5, 2004, varied across
<br /> the site, but was generally toward the southeast The average hydraulic gradient was calculated to
<br /> be 0 02 ft/ft or approximately 105 ft/mile A summary of groundwater monitoring data is
<br /> • presented in Table 1
<br /> S\Enviromental12529IVcports\IQR-2004 doc 2
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