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i — 1, <s CLEARWATER K 0 L P 1 \ C Env:ro remea�af Services Following recovery of water levels to at least 80% of their static levels, groundwater samples were collected from the monitoring wells using dedicated polyethylene bailers Samples were transferred to laboratory supplied containers, labeled, documented on a chain-of-custody form, and placed on ice in a cooler for transport to the project laboratory ' Purging devices were decontaminated between wells in an Alconox@ wash followed by double rinse in clean tap water to prevent cross-contarrunation Purge water and r>nseate was stored on-site in labeled 55-gallons drums pending future removal and disposal Laboratory Analysis of Soil and Grab Groundwater Samples All soil and groundwater samples were analyzed by Entech, a DHS-certified laboratory located in Sunnyvale, California Groundwater samples were analyzed for concentrations of TPHg and BTEX by EPA Methods 8015 (modified)/8020 and for Five Fuel Oxygenates (MTBE, TBA, ETBE, DIPE, TAME) and Lead Scavengers (1,2-DCA, EDB) by EPA Method 8260B Soil samples were analyzed for TPHg and BTEX by EPA Methods 8015 (inodified)J8020 and for MTBE by EPA Method 8260E Results Hydrog_eollo y The soil types observed during this phase of drilling were consiGtent with those previously encountered at the site Lithology consisted mostly of interbedded silty sands and sandy silts with an occasional layer that contained clay mixed with silt Water was first encountered in the soil borings at approximately 23 to 25 ft bgs Water was typically observed in layers of more sandy soil, which tended to be more water- bearing than the more silty or clayey layers On February 7, 2000, static groundwater in the wells was present beneath the site at depths ranging from approximately 15 to 17 feet bgs Gauging data, combined with well elevation data, were used to calculate groundwater elevations in these wells, and to generate a groundwater elevation contour map The groundwater flow direction was calculated to be toward the southwest at a gradient of 0 001 ft/ft (Figure 3) This groundwater flow direction is not the most common direction observed However, the flow direction has been observed to change direction from the northeast to the southwest depending on the time of year This fluctuation of flow direction is most likely due to local agricultural irrigation activities in the area of the site Distribution of Residual Contaminants in Soil Samples from all depths in borings CB2, CB3, and CB4 were essentially free of all contaminants Notable concentrations of TPHg were only found in samples from CB1 at depths of 15, 20, and 25 feet bgs These TPHg concentrations ranged between 190 to 240 mg/kg These detections most likely represent the last of the residual contaminants remaining in soil following remediation It is noteworthy that all soil samples collected at the 30 foot depth interval from all borings were free of detectable contaminant levels Analytical results from the recent confirmation soil borings are ZB107C Conf Bonngs/GWMR 1Q00 4 March 27, 2000