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A S S d C I A T E S I N C GROUNDWATER MONITORING On September 22, 1998, an ATC Associates technician measured the depth to water in wells MW-1 through MW-5, and RW-1, piezometer PZ-1, and vapor wells VW-1, VW-2s, VW-3d, VW-4, VW-5s, and VW-5d The water level was not measured in vapor well VW-2d due to an obstruction in the casing that made the well inaccessible 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 RW-1 were used to evaluate the groundwater flow direction and gradient beneath the site The groundwater elevation beneath the site decreased an average of 1 10 feet since June 3, 1998 The groundwater gradient for September 22, 1998 showed groundwater flowing to the east at a gradient of approximately 0 003 ft/ft which is consistent with previous groundwater gradients The groundwater gradient for September 22, 1998, is depicted on Figure 3 GROUNDWATER SAMPLING On September 22, 1998, groundwater samples were collected from wells MW-1 through MW-5 for laboratory analyses Well RW-1 was not sampled at the direction of Mr Jeff Wong of the PHS/EHD The field methods used are presented in Attachment I Field purge logs are included in Attachment 2 At the direction of Mr Jeff Wong of the PHS/EHD only groundwater samples from wells MW-1 and MW-2 were submitted for laboratory analysis The other samples were not analyzed because the groundwater level was above the top of screen in the monitoring wells 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 820 parts per billion (ppb) Benzene, toluene, xylenes, and MTBE were also detected in well MW-1 TPHg, BTEX, and MTBE constituents were not detected in the sample from well MW-2 TPHd was detected in the samples from wells MW-1 and MW-2 at concentrations of 460 ppb and 67 ppb, respectively The laboratory results of TPHd were w 162574162574 0119436713QSR98doc 2