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Yi+ is CLEAkWATER G a o U r I N C Environments!Services GROUNDWATER MONITORING AND SAMPLING RESULTS Depth to groundwater 8 38 (MW-4) to 11 10 (MW-8) feet below top of casing Flow direction Southeast at 0 006 ft/ft TPHg concentration range < 50 µg/L (MW-2, MW-4) to 12,000 gg/L (MW-5B) Benzene concentration range <0 50 µg/L (MW-2, MW-3, MW-4, MW-7) to 740 ug/I~ (MW-5B) MTBE concentration range <5 0 gg/L (MW-2, MW-3, MW-4, MW-7, MW-8) to 100µg/L (MW-5B) Remarks MTBE was detected by EPA 8020 in the groundwater sample collected from MW-5B this quarter Previously MTBE has been confirmed as "non-detectable" by EPA 8260 in all monitoring wells sampled at the site Monitoring well MW-4 was omitted from the Groundwater Elevation Contour Map PROJECT STATUS & RECOMMENDATIONS The contaminant plume is currently delineated and being monitored on a quarterly basis Clearwater recommends completing quarterly sampling for four quarters, which started in the second quarter 2000, to examine trends in hydrocarbon concentrations and distribution The last of the four monitoring events is scheduled for the first quarter 2001 If hydrocarbon concentrations exhibit a downward trend within the core of the plume, then Clearwater will recommend collecting data to document remediation by natural attenuation If concentrations do not fall, then Clearwater will evaluate other options for the reduction of contaminant concentrations ATTACHMENTS • Site Vicinity Map (Figure 1) • Site Plan (Figure 2) • Groundwater Contour Map - 11/14/00 (Figure 3) • Hydrocarbon Distribution Map - 11/14/00 (Figure 4) • Groundwater Elevations and Analytical Results (Table 1) • Clearwater Gauging Data/Purge Calculations and Well Purging Data • Certified Laboratory Reports and Chain-of-Custody Form • Clearwater Groundwater Monitoring and Sampling Protocols CGI-ZB 178C-4QT00 3 November 29, 2000