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Quarterly Monitoring and Sampling Report(Q2 2001) 4 Ranch Market 23569 Santa Fe Road Riverbank California May 10 2001 . service from the Aero Pure Water supply tank was disconnected and the water valve was opened, allowing DW-2R to supply water to the home on the Panto}a Property Groundwater Monitoring Water Table Elevations and Gradient On April 11, 2001, SECOR personnel measured the depth to water in each of the ten site-related groundwater monitoring wells (Table 3) 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 0 005 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 second quarter 2001 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 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 ten 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 ten groundwater monitoring wells was stored in drums on site, pending characterization and disposal Groundwater Sampling Procedures The groundwater monitoring wells were re-monitored to verify at least 80% recovery prior to sampling Adequate recovery was observed in the purged wells prior to sampling A disposable bailer was used to collect the groundwater samples All samples were collected in appropriate containers, preserved on ice, and transported under chain-of-custody manifest to Kiff Analytical LLC located in Davis, California The water samples were analyzed for TPHg, BTEX, 1,2-DCA, EDB, and 5 oxygenates using EPA method 8260B Groundwater Analytical Results Historical and recent groundwater laboratory analytical results are summarized in Table 3 The highest TPHg and benzene concentrations were detected in monitoring well MW4 at 41,000 File Ranch Market\Report\Rtverbank-01-2Qdoc