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ATC Associates Inc <br /> ` YVATC <br /> 1117 Lone Palm Avenue, Suite B <br /> Modesto, California 95351 <br /> 209-579-2221 <br /> Assoc I A T E s I NC Fax 209-579-2225 <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) MW7 was <br /> replaced by VE3 Soil samples collected from borings 13101, B103, B104, VE3, and VE1 <br /> contained detectable concentrations of TPHg and 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 16, 2005, ATC personnel collected groundwater samples from MW I through MW6, <br /> MW8, MW9, and the on-site domestic well The locations of the monitoring wells are shown on <br /> Figure 2 Prior to collection of groundwater samples, the depth to water, pH, electrical <br /> conductivity, and temperature were measured Turbidity was visually observed 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 /> collected from each well using dedicated disposable bailers <br /> The groundwater samples collected from each well were submitted to Argon Laboratories Inc <br /> (Environmental Laboratory Accreditation Program Certification No 2359), a California-certified <br /> analytical laboratory, for chemical analysis of TPHg and utilizing EPA Method 8015B, BTEX <br /> utilizing EPA Method 8021B, 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 /> Drums containing investigative derived wastes (IDW) were sampled to evaluate disposal options <br /> These samples were submitted to Argon Laboratories for chemical analysis of TPHg, BTEX and <br /> MTBE <br /> GROUNDWATER FLOW DIRECTION <br /> Water Ievels were measured in MWI through MW6, MW8, and MW9 on February 16, 2005 <br /> ranged from 70 85 to 74 91 feet below the tops of the well casing elevations This represents an <br /> increase in groundwater table elevation by an average of 128 feet from the November 19, 2004, <br /> sampling event The data from MW6 was not used for contouring because it is screened in a <br /> deeper interval The water level data was used to develop the groundwater elevation contour <br /> map (Figure 3) Shallow groundwater flow in the uppermost aquifer varied across the site on <br /> February 16, 2005 but was generally toward the southeast The average hydraulic gradient was <br /> . calculated to be 0 05 ft/ft or approximately 264 ft/mile A summary of groundwater monitoring <br /> data is presented in Table I <br /> S IenviromentaK252911reports\IQR-2005 doc 2 <br />