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t CUARWATER G R O U P, I t T C. 3A FIELD ACTIVI ES Clearwater began quarterly groundwater sampling at the subject location in February 1995. - All work has been performed_in accordance with Clearwater Field Procedures (previously submitted), and under the directive and guidelines established by the PHS/EHD and the Regional Water Quality Control Board. 'The monitoring wells were sampled on December 21, 1995 under the supervision of'Mr. Ron Rowe of the PHS/EHD. All wells were gauged to the nearest hundred'h of a foot and then purged of a minimum of three well volumes. Temperature, H and conductivity of the purged water were monitored to ensure collection of a representative groundwater sample. F, Groundwater samples were collected from the monitoring wells using dedicated' polyethylene bailers and placed in appropriate sample containers. Samples were Z2 0 labeled, documented on a chain-of-custody form, and stored in a cooler for transport to American Environmental Network (AEN), a tate-certified laboratory located in ► Pleasant Hill, California. ' Well gauging, purging and sampling data is presented in ! Appendix A. All groundwater samples were analyzed for TPHg and TPHd by EPA Method 3510/GC-FID, and for BTEX by EPA Me od 8020 (modified). 4.0 RESULT 4.1 Water Level Monitoring Data On December 21 the depth to ground water int ae three wells ranged from 19.40 to 20.75 feet bgs (Table 1). - Groundwater flow w as estimated to be northerly at an approximate gradient of 0.16%; the estimated groundwater elevation contours are shown on.Figure 3. 4.2 Groundwater Sample Analytical Results P Y TPHg, TPHd, and BTEX were not detected in concentrations exceeding method detection limits in any .of the three groundwater samples (Table 1). The analytical results are consist with the results of groundwater samples collected on October 18, 1995. Concentrations of TPHd ranged from 100 to 530 ppb in samples collected during February and May, 1995. Analytical results are displayed graphically on F gore 4, and laboratory reports and chain-of-custody forms are attached as Appendix B. D-104 4Q95 2 January 26, 1996