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• AS S O C I ATE S IN C .
<br /> In January 2003, GHH Engineering, Inc. (GHH) advanced three cone penetrometer borings and
<br /> three soil borings to depths ranging from 104 feet bgs to 122 feet bgs.
<br /> In May 2003, GHH advanced four soil borings, MW6a, MW6b, MW7a, and MW7b to the east of
<br /> the site. These borings were completed as well clusters with MW6 and MW7a advanced to a
<br /> depth of approximately 75 feet bgs, and MW6b and MW7b advanced to a depth of
<br /> approximately 94 feet bgs. GHH also installed well EW1 in the southeast portion of the site.
<br /> Site activities were summarized in GHH's Second Quarter 2003 Groundwater Monitoring
<br /> Report and Additional Assessment Report, dated June 2003.
<br /> In January 2004, an ATC geologist supervised the installation of five spargepoint wells
<br /> associated with an ozone injection system. Each spargepoint has a shallow and deep injection
<br /> well for the ozone. The shallow spargepoints were installed to a depth of approximately 75 feet
<br /> bgs and the deep spargepoints were installed at a depth of approximately 108 feet bgs. From
<br /> February 17 to approximately April 20, 2004, an ATC geologist supervised the installation of
<br /> groundwater monitoring wells MW6c, MW7c, MW8, MW9a, MW9b, MW9c, MW10a, MW10b,
<br /> and MWIOc.
<br /> SAMPLING ACTIVITIES
<br /> On June 3, 2004, ATC personnel collected groundwater samples from monitoring wells MW1
<br /> through MW5, MW6a, MW6b, MW6c, MW7a, MW7b, MW7c, MW8, MW9a, MW9b, MW9c,
<br /> MW10a, MW10b, MW10c and EWL The locations of the wells are shown on Figure 2. Prior to
<br /> collection of groundwater samples, the depth to water was measured in MW1 through MW5,
<br /> MW6a, MW6b, MW6c, MW7a, MW7b, MW7c, MW8, MW9a, MW9b, MW9c, MW10a,
<br /> MW10b, MWIOc and EW1 and the pH, electrical conductivity, and temperature were measured
<br /> in groundwater purged from the monitoring wells and recorded. A minimum of three well casing
<br /> volumes were purged from each monitoring well prior to sampling, except for wells MW6c,
<br /> MW7c, MW9b, and MW10c which were bailed dry. Approximately 1.2, 1.3, 1.4 and 2.1 well
<br /> volumes of water were removed from MW6c, MW7c, MW9b, and MW10c, respectively. The
<br /> wells were allowed to recover and samples were collected from each well using disposable
<br /> polyethylene bailers. After samples were collected, dissolved oxygen (DO) concentrations were
<br /> measured.
<br /> The groundwater samples collected from each well were submitted to State-certified Argon
<br /> Laboratories Inc. (ELAP Cert. No. 2359) in Ceres, California for chemical analyses of total
<br /> petroleum hydrocarbons as gasoline (TPHg) and total petroleum hydrocarbons as diesel (TPHd)
<br /> _ .__utilizing.EPA Method 8015B; benzene, toluene, ethylbenzene, and xylenes (BTEX) utilizing =
<br /> EPA Method 802113; and methyl tertiary butyl ether (MTBE), ethyl tertiary butyl ether (ETBE)
<br /> di-isopropyl ether (DIPE), tertiary amyl ether (TAME), tertiary butyl ether (TBA), 1,2-
<br /> dichloroethane (1,2-DCA), and 1,2-dibromoethane (EDB) utilizing EPA Method 8260B.
<br /> • Groundwater well purge and sample logs are contained in Attachment 1.
<br /> S:1268231QM reports12004 2QR.doc 2
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