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Groundwater samples were collected from monitoring wells MW-1, MW-2, and MW-3. Prior to collection of groundwater samples a minimum of three well casing volumes were purged. The depth-to-water, pH, electrical conductivity, and temperature were measured and allowed to stabilize before groundwater samples were collected. Additionally, Eh was measured in the groundwater purged from the wells. Samples were then collected from each well using disposable bailers. Purge water was contained in 55-gallon DOT approved drums. Purge water from monitoring well MW-1 from the previous sampling event did not contain detectable concentrations of petroleum hydrocarbons and was discharged to the ground surface. Groundwater well purge and sample logs are provided in Appendix A. The groundwater samples collected from each well were submitted with Chain of Custody Record to Sequoia Analytical Laboratories, Inc. in Redwood City, California, a State Certified laboratory. The samples were analyzed for TPHg and BTEX by EPA methods 801518020, respectively; MTBE by EPA method 8020; and dissolved oxygen, carbon dioxide, alkalinity, nitrate, sulfate, and ferrous iron. Groundwater analytical results are summarized in Table 2. The Chain of Custody Record, laboratory analytical reports, and chromatograms are included in Appendix B. RESULTS OF LABORATORY ANALYSES Results of this quarter's laboratory analysis of groundwater samples from monitoring wells MW- 1, MW-2 and MW-3 indicate the presence of petroleum hydrocarbons in groundwater in > : monitoring wells MW-2 and MW-3. TPHg and BTEX concentrations in well MW-2 were significantly lower (approximately one order of magnitude) than last quarter. In MW-3, concentrations of TPHg and BTEX were similar to previous quarters. MTBE was detected only in well MW-2. MTBE was not confirmed through analysis by EPA Method 8260 per recommendations by Ron Rowe of PHSIEHD (Rowe 1996). No petroleum hydrocarbons were detected in monitoring well MW-1. The analytical results of the analysis of groundwater samples for dissolved oxygen, carbon dioxide, alkalinity, nitrate, sulfate, and ferrous iron are summarized in Table 2. CONCLUSIONS Based on the results of this quarterly monitoring and sampling, Smith Technology recommends continued groundwater monitoring and sampling of wells MWA, MW-2 and MW-3 in order to detect changes in groundwater quality beneath the site. w:1951221Rq*rtsl4QMR1996.doc 4 • smTH