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fl 1 ATC Associates Inc 1117 Lone Palm Avenue, Surte B (: Modesto, Califorma 95351 VYAkTC 209-579-2221 ASSOCIATE s INC Fax 209-579-2225 In June and July 2000, WHF supervised the advancement of ten soil bonngs at the site and completed five of the borings as groundwater monitoring wells MW5, MW6, MW8, MW9, and MW 10, and three of the borings as vapor extraction wells VE 1, 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 Califorma licensed land surveyor and presented in Table 3 SAMPLING ACTIVITIES On November 19, 2004, groundwater samples were collected by ATC personnel from monitoring wells NMI 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 and turbidity was visually observed 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 (Environmental Laboratory Accreditation Program Certification No 2359), a California-certified analytical laboratory, for chemical analysis of TPHg and utilizing EPA Method 8015B, BTEX utilizing EPA Method 8021B, and MTBE, tertiary butyl alcohol (TBA), di-isopropyl ether (RIPE), ethyl tertiary butyl ether (ETBE), tertiary amyl methyl ether (TAME), 1,2-dichloroethane (1,2-DCA), and 1,2 dibromoethane (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 MW 1 through MW6, MW8, and MW9 on November 19, 2004, ranged from 72 03 to 76 20 feet below the tops of the well casing elevations This represents an increase in groundwater table elevation by an average of 1 44 feet from the August 17, 2004, sampling event The data from MW6 was not used for contouring because it is screened in a deeper interval The water level data was used to develop the groundwater elevation contour map (Figure 3) Shallow groundwater flow in the uppermost aquifer varied across the site on August 17, 2004, but was generally toward the southeast The average hydraulic gradient was calculated to be 0 03 ft/ft or approximately 158 ft/mile A summary of groundwater monitoring data is presented in Table 1 s\envwomentW\25291 Veports\4QR-2004 dm 2