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A S S O C I A T E S I N C GROUNDWATER MONITORING On December 22, 1998, an ATC Associates technician measured the depth to water in wells MW- 1 through MW-5, and RWA, piezometer PZ-1, and vapor well VW-3d 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 and RWA were used to evaluate the groundwater flow direction and gradient beneath the site The groundwater elevation beneath the site decreased an average of 0 19 feet since September 22, 1998 The groundwater gradient for September 22, 1998 showed groundwater flowing to the east at a gradient of approximately 0 002 ft/ft which is consistent with previous groundwater gradients The groundwater gradient for December 22, 1998, is depicted on Figure 3 GROUNDWATER SAMPLING On December 22, 1998, groundwater samples were collected from wells MWA 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 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 3 ANALYTICAL RESULTS Results of laboratory analyses indicated dissolved TPHg was detected in the sample from well MW-1 at a concentration of 2,400 parts per billion (ppb) No TPHg was detected in any other site momtonng wells that were sampled Benzene (800 ppb) and TPHd (290 ppb) were also detected in well MW-1 Low concentrations of BTEX constituents and TPHd were detected in well MW-3 Low concentrations of benzene and xylenes were detected in well MW4 No other BTEX constituents or MTBE were detected in any of the wells The laboratory results of TPHd were reported as unidentified hydrocarbons in the C9-C24 range MTBE was detected in the sample from well MW-4 at concentration of 250 ppb, however flus detection was not confirmed by laboratory EPA method 8260 In November 1997 groundwater samples from wells MW-1 through MW-5 were analyzed for fuel oxygenates utilizing EPA . method 8260 and none were detected but groundwater was above the top of screen in these wells w 162574162574 0119436714QSR98doc 2