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S E C 0 R • Mr Michael Infurna—SJCEHD January 29, 2003 Page 4 Remedial Well and System Installation Between July 8 and 15, 2002, a total of 20 ozone sparge wells (S-1 through S-20) and four vapor extraction wells (V-7 through V-10) were installed to depths ranging from approximately 30 to 45 feet bgs The analytical results of selected sod samples collected during the well installation are summarized in Table 1 and the details related to the well completions are summarized in Table 2 Following installation of the wells, the lateral ozone injection lines, sod vapor extraction lines, and remediation compound were installed The SVE lines were stubbed up into the remediation compound into a manifold that was connected to the 500 scfm catalytic oxidizer The 20 ozone sparge pipes were stubbed up into a manifold and connected to the 6 cfm ozone injection skid and generator The location of piping runs and remediation compound are shown on Figure 3 The equipment layout within the compound is shown on Figure 4 Soil vapor extraction was initiated at the site on September 26, 2002, under Authority to Construct number N-4613-1-0, issued by the San Joaquin Valley Air Pollution Control District (SJVAPCD) Ozone sparging was initiated at the site on November 20, 2002 Details of the remediation well installation and system startup are described in SECOR's Remediation Well and Soil Vapor Extraction System Installation Report, dated November 27, 2002 Groundwater Monitoring iWater Table Elevations and Gradient On October 1, 2002, SECOR personnel measured the depth to water in each of the ten site-related groundwater monitoring wells (Table 3) The depth to water was not measured in well MW-7 due access limitations A water level indicator was used to gauge the wells to the nearest 0 01 foot A groundwater elevation contour map indicates that groundwater flow is generally toward the south at a gradient of 0 002 ft/ft (Figure 4) Current and historical groundwater monitoring data are summarized in Table 3 Separate-Phase Petroleum Thickness Well gauging and sampling efforts for the fourth quarter 2002 did not detect separate-phase petroleum hydrocarbons (SP) in any of the wells monitored (Table 3) Historically, SP has not been present in the groundwater monitoring wells at the site Groundwater Sampling Well Purging f Groundwater monitoring wells were purged using a submersible pump and disposable bailers until pH, temperature, and conductivity readings had stabilized Temperature, conductivity, and pH readings were recorded in the wells, at regular purge intervals of one casing volume, with a portable instrument that was calibrated before the wells were purged Water purged from the eleven groundwater monitoring wells was stored in drums on site, pending characterization and disposal Domestic Well Groundwater Sampling Procedures • Domestic wells were purged by turning on the water at the well, thus draining the well's holding tank and filling the tank with fresh water from the aquifer Once the tank has been recharged, water Riverbank-02-40 doc SECOR international incorporated i