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�� K4 ATC Associates Inc 1117 Lone Palm Avenue, Suite B (: Modesto, California 95351 V %Tc 209-579-2221 A S S O C I A T E S t N C Fax 209-579-2225 In June and July 2000, WHF supervised the advancement of ten soil borings at the site and completed five of the borings as groundwater monitoring wells (MW5, MW6, MW8, MW9, and MW10), and three of the borings as vapor extraction wells (VE1, VE2, and VE3) MW7 was replaced by VE3 Soil samples collected from borings 13101, B103, B104, VE3, and VE1 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 20, 2005, ATC personnel collected groundwater samples from MWI through MW6, MW8, MW9, and the on-site domestic well 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 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 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 801513, BTEX utilizing EPA Method 8021B, and MTBE, tertiary butyl alcohol (TBA), di-isopropyl ether (DIPE), 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 I GROUNDWATER FLOW DIRECTION Water levels were measured in MWI through MW6, MW8, and MW9 on May 20, 2005 and ranged from 70 24 to 74 80 feet below the tops of the well casing elevations This represents a decrease in groundwater table elevation by an average of 0 34 feet from the February 16, 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 May 20, 2005 but was generally toward the southeast The average hydraulic gradient was calculated to be 0 05 ft/ft or approximately 264 ft/mile A summary of groundwater monitoring data is presented in Table I • S Ienvlromenta11252911reportsl2ndQR-2005 doc 2