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(!0tkTC . ASSOCIATE S I N C . In August 2000, JPCA advanced soil boring 131, MW4, and MW5. MW4 and MW5 were completed as groundwater monitoring wells. B 1 was advanced to a depth of 115 feet bgs and MW4 and MW5 were installed to a depth of 75 feet bgs. Soil and groundwater samples were collected and analyzed. Site activities were summarized in JPCA's 2nd Phase II Environmental Assessment Report, dated October 25, 2000. In January 2003, GHH Engineering, Inc. (GHH) advanced three cone penetrometer borings and three soil borings to depths ranging from 104 feet bgs to 122 feet bgs. In May 2003, GHH advanced MW6a, MW6b, MW7a, and MW7b to the east of the site. These borings were completed as well clusters with MW6a and MW7a advanced to a depth of approximately 75 feet bgs, and MW6b and MW7b advanced to a depth of approximately 94 feet bgs. GHH also installed EWI in the southeast portion of the site. Site activities were summarized in GHH's Second Quarter 2003 Groundwater Monitoring Report and Additional Assessment Report dated June 2003. In January 2004, an ATC geologist supervised the installation of five injection wells (IW1 - IW5) associated with an ozone injection system. Each injection well has a shallow and deep spargepoint for the ozone. The shallow spargepoints were installed to a depth of approximately 74.0 feet bgs and the deep spargepoints were installed at a depth of approximately 107.7 feet bgs. From February 17 to approximately April 20, 2004, an ATC geologist supervised the installation of MW6c, MW7c, MW8, MW9a, MW9b, MW9c, MWIOa, MWIOb, and MW1Oc. The data for the well installation was submitted in an ATC's report entitled Summary Report of Subsurface Investigation and dated February 24, 2005. 2.0 GROUNDWATER MONITORING ACTIVITIES On December 13, 2004, ATC personnel collected groundwater samples from MW 1 through MW5, MW6a, MW6b, MW6c, MW7a, MW7b, MW7c, MW8, MW9a, MW9b, MW9c, MW10a, MW10b, MW10c and EWL The locations of the wells are shown on Figure 2. The depth to water was measured in all wells prior to collection of groundwater samples. The pH, electrical conductivity, and temperature were then measured in the groundwater purged from the monitoring wells and recorded. Turbidity was visually observed and recorded. MW6c, MW7C, MW913 and MW10C were bailed dry before a minimum of three well casing volumes were purged. These wells were allowed to recover to the extent practical during the field activities and then sampled for chemicals of concern (CDCs).- A minimum of three well casing volumes were purged from each remaining groundwater monitoring well prior to sampling. After samples were collected, dissolved oxygen (DO)concentrations were measured. The groundwater samples collected ftom each well were submitted to State-certified Argon Laboratories Inc. (Environmental Laboratory Accreditation Program Cert_ No. 2359) in Ceres, California for chemical analyses of total petroleum hydrocarbons as gasoline (TPHg) and total SA268231QM reporu\2004 4QR.doc 2