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CLEA�k__'W�i6ATER • frsciron mrntal Serc>:ces 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 Additionally, a water sample was collected from the on-site domestic well (DW) 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-contamination Purge water and rinseate was stored on-site in Iabeled 55-gallons drums pending future removal and disposal All 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 MTBE by EPA Method 8260B Groundwater Monitoring Results On May 8, 2000, static groundwater in the wells was present beneath the site at depths ranging from approximately 16 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 0 004 ft/ft (Figure 3) This groundwater flow direction is similar to that in the previous quarters event, but is not the most common direction observed 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 Dissolved-phase contaminant concentrations were only present at low levels this monitoring event Low levels of contaminants were observed in both MW-1 and MW-2 Maximum contaminant levels found in these two wells were TPHg 360 µg/L (MW-1), benzene 0 84 µ%/L (MW-1), and MTBE 30 lig/L (MW-2) These levels of contaminants are less than observed in the first quarter 2000 monitoring event Samples from the on-site domestic well continue to be free of any petroleum contaminants Considering the well was not impacted by elevated contaminants levels prior to remediation, it appears that the well is not threatened by the minimal post-remediation contaminant levels now present in the soil and shallow groundwater beneath the site MTBE was the only fuel oxygenate tested for this quarter The previous results indicated that it was the only fuel oxygenate detected in groundwater samples MTBE was detected this quarter in MW-1 (5 8 gg/L) and MW-2 (30 gg/L) These levels of MTBE are lower than observed the previous quarter 7B107C GWMR 2Q00 3 May 24,20(x0