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• SWTH The depth to water measurements and the elevations of the well casings (Table 1) were used to evaluate the groundwater flow direction and gradient beneath the site (refer to attached Field Procedures) Groundwater elevation beneath the site rose an average of 1 79 feet since March 23, 1995 Groundwater flow direction was generally to the northeast at a gradient of approximately 0 0034 ft/ft as depicted on Figure 3 On May 30, 1995, groundwater samples were collected from wells MW-1 through MW-5 for laboratory analyses The field methods used are presented in Attachment 1 Field purge logs are included in Attachment 2 Groundwater samples were analyzed by Sequoia Analytical for total purgeable petroleum hydrocarbons (TPHg) using Environmental Protection Agency (EPA) Method 8015 modified, total extractable petroleum hydrocarbons (TPHd) using EPA Method 8015 modified, and benzene, toluene, ethylbenzene, and total xylenes (BTEX) using EPA Method 8020 Copies of the laboratory reports and chain of custody documentation are included in Attachment 3 Results of laboratory analyses indicated dissolved TPHg was detected in the samples from wells MW-1 and MW-2 at 3,900 parts per billion (ppb) and 74 ppb, respectively The TPHg in well MW-2 was reported by the laboratory as an unidentified hydrocarbon <C8 No TPHg was detected in any other site monitoring wells BTEX constituents were detected in well MW-1, most notably benzene at 480 ppb Hydrocarbon constituents detected in well MW-1 generally increased by one order of magnitude since March 1995 No BTEX constituents were detected in any other site monitoring wells TPHd was detected in wells MW-1 and MW-5 at 1,000 ppb and 210 ppb, respectively The laboratory results of TPHd were reported as unidentified hydrocarbons in the C9-C24 range No TPHd was detected in any other site monitoring wells No petroleum hydrocarbons were detected in monitoring wells MW-3 or MW-4 Results of laboratory analyses are summarized in Table 2 SUMMARY AND RECOMMENDATIONS The groundwater flow direction and gradient was generally consistent with those evaluated during previous events Dissolved gasoline hydrocarbons were detected in the samples from wells MW-1 and MW-2 Dissolved hydrocarbons in the diesel range were detected in wells MW-1 and MW-5 during the reporting period Dissolved TPHg and TPHd concentrations were below laboratory detection limits in monitoring wells MW-3 and MW-4. 38009 10k2QSR95doc 2