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31 FIELD SERVICES AND LABORATORY ANALYSIS Geocon performed gioundwater monitoring and sampling on January 9, 2004 to determine water table elevation and the distribution of dissolved hydrocarbons in groundwater monitoring wells Two ' offsite and one onsite domestic well were sampled to determine if potable water supplied to adjacent residents are impacted with petroleum hydrocarbons Groundwater elevation data and contaminant ' concentrations in groundwater are reported in Tables l and 2 ' Operation and maintenance (O&M) services were performed for the SVE and ozone sparge systems for the reporting period between October 15, 2003 and January 9, 2004 ' 31 Water Table Elevations And Gradient On January 9, 2004, Geocon personnel measured the depth to water in each of the ten Site-related ' gioundwater monitoring wells 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 was generally toward the south at a gradient of 0 002 ft/ft as depicted in Figure 4 Groundwater monitoring data is ' presented in Table 1 32 Quarterly Groundwater Sampling Groundwater monitoring wells were purged using a submersible pump until pH, temperature, and conductivity readings had stabilized Temperature, conductivity, and pH readings were recorded for each well for each casing volume removed using a field instrument Water purged from the wells is stoied in a 500-gallon above ground storage tank within the remediation system compound Domestic wells DW-1, DW-211 and DW-3 were purged by opening a spiget at the well head works, ' draining the well's holding tank, and allowing the tank to re-fill with fresh water pumped from the aquifer Once the tank had been recharged, water samples were collected directly from a spigot at the holding tank Domestic wells DW-2R, DW-3, and DW-4 are on a quarterly sampling schedule and ' DW-1 is on a monthly sampling schedule However, the residence that is serviced by domestic well DW-4, located at 23665 South Santa Fe Road, had no serviceable lune to the potable water supply ' available at the tune of the quarterly sampling event Onsite domestic well DW-1 has vitiate concentrations that exceed the drinking water standard San Joaquin County Environmental Health has requested the abandonment and replacement of domestic well DW-1 The replacement is ' scheduled for First Quarter 2004 • 1 ' Froic,ct No 58643-06-01 4- February 18 2004