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} A S S O C I A T E S I N C GROUNDWATER MONITORING On December 14, 1999, an ATC Associates technician measured the depth to water in groundwater wells MW-1 through MW-5, and RW-1, piezometer PZ-1, and vapor wells VW-1, VW-2d, VW-3, and VW-5d No floating product was noted in any site well Groundwater monitoring data are summarized in Table 1 The depth to water measurements and the elevations of the well casings (Table 1) of wells MW-1 through MW-5 were used to evaluate the groundwater flow direction and gradient beneath the site The groundwater elevation beneath the site decreased an average of 165 feet since July 6, 1999 The groundwater gradient for December 14, 1999 showed groundwater flowing to the east-northeast at a gradient of approximately 0 002 ft/ft which is consistent with previous groundwater gradients The groundwater gradient for December 14, 1999 is depicted on Figure 3 GROUNDWATER SAMPLING On December 14, 1999, as requested by Mr Jeff Wong of PHS/EHD, groundwater samples were • collected from groundwater wells MW-1, MW-3, and MW-5 and also from vapor wells VW-1, VW-2d, VW-3, and VW-5d for laboratory analyses Copies of field purge logs are included in Attachment 1 Groundwater samples were analyzed by State-certified 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, total xylenes (BTEX) and methyl tertiary butyl ether (MTBE) using EPA Method 8020 Copies of the laboratory reports and chain of custody documentation are included in Attachment 2 ANALYTICAL RESULTS Groundwater Monitoring Wells Results of laboratory analyses indicated that dissolved TPHg [3,350 parts per billion (ppb)], benzene (1,180 ppb) and TPHd (731 ppb) were detected in groundwater well MW-1 Benzene exceeded the maximum contarninant level (MCL) Low concentrations of toluene, ethyl benzene, and xylenes were also detected in well MW 1 but were reported well below their respective MCLs Low concentrations of TPHd were detected in well MW-3 No other BTEX constituents were detected in any of the groundwater wells sampled The laboratory results of TPHd were reported as unidentified hydrocarbons in the C9-C24 range MTBE was not detected in any of the samples from wells MW-1, MW-3 or MW-5, however the detection level for the sample from MW-1 was elevated due to dilution factors