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A S S O C I A T E S I N !C 5 MW10, and three of the bonngs as vapor extraction wells VE1, VE2, and VE3 Groundwater monitoring well MW7 was replaced by vapor extraction well VE3 Soil samples collected from borings B101, B103, B104, VE3, and VE 1 contained detectable concentrations of TPHg and BTEX On August 16, 2003, the well casing elevations were re-surveyed by Condor Earth Technologies for elevation to within 0 01 foot under the supervision of a California licensed land surveyor and presented in Table 3 SAMPLING ACTIVITIES On May 27, 2004, groundwater samples were collected by ATC personnel from monitoring wells MW 1 through MW6, MW8, MW9, and the on-site domestic well Well MW 10 has an obstruction at approximately 20 feet bgs and was not sampled 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 groundwater purged from 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 • The groundwater samples collected from each well were submitted to Argon Laboratories Inc (ELAP Cert No 2359), a California-certified analytical laboratory, for chemical analysis of TPHg and total petroleum hydrocarbons as diesel (TPHd) utilizing EPA method 8015B, BTEX utilizing EPA method 802113, and MTBE, tertiary butyl alcohol (TBA), d1-isopropyl ether (DIPE), ethyl tertiary butyl ether (ETBE), tertiary amyl methyl ether(TAME), 1,2-dichloroethane (1,2-DCA), and 1,2 d>bromoethane (EDB) utilizing EPA method 8260B Groundwater well purge and sample logs are contained in Attachment 1 GROUNDWATER FLOW DIRECTION Water level measurements collected from wells MWI through MW6, MW8, and MW9 on May 27, 2004, ranged from 7143 to 76 32 feet below the tops of the well casing elevations This represents a decrease in groundwater table elevation by an average of 1 68 feet from the February 5, 2004, sampling event The data from MW6 was not used for contouring because it is screened in a deeper interval The water level data were used to develop the groundwater elevation contour map (Figure 3) Assuming horizontal isotropic conditions, groundwater flow in the uppermost aquifer beneath the site on May 27, 2004, varied across the site, but was generally toward the southeast The average hydraulic gradient was calculated to be 0 04 ft/ft or approximately 211 ft/mile A summary of groundwater monitoring data 1s presented in Table 1 ANALYTICAL RESULTS • The groundwater samples collected from wells MW1, MW2, MW4, MW5, MW6, and MW9 and contained detectable concentrations of TPHg and BTEX constituents The groundwater samples S 1Enviromental125291\reports\?QR-2004 doc 2