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^ab�L i r 3 AV�a A .cw<3o <br /> lr <br /> a <br /> > >F <br /> ri} <br /> A S S O C I A T E S I N C <br /> GROUNDWATER MONITORING <br /> On July 6, 1999, an ATC Associates technician measured the depth to water in groundwater wells <br /> MW-1 through MW-5, and RW-1, piezometer PZ-1, and vapor wells VW-4, VW-5s, and VW- <br /> 5d No floating product was noted in any site well Groundwater monitoring data are <br /> summarized in Table 1 <br /> The depth to water measurements and the elevations of the well casings (Table 1) of wells MW-1 <br /> through MW-5 and RW-1 were used to evaluate the groundwater flow direction and gradient <br /> beneath the site The groundwater elevation beneath the site increased an average of 0 86 feet <br /> since December 22, 1998 The groundwater gradient for July 6, 1999 showed groundwater <br /> flowing to the east-northeast at a gradient of approximately 0 002 ft/ft which is consistent with <br /> previous groundwater gradients The groundwater gradient for July 6, 1999 is depicted on Figure <br /> 3 <br /> GROUNDWATER SAMPLING <br /> On July 6, 1999, as requested by Mr Jeff Wong of PHS/EHD, groundwater samples were <br /> collected from groundwater wells MW-1 through MW-5, RW-1, and vapor wells VW-4, VW-5s, <br /> and VW-5d for laboratory analyses The field methods used are presented in Attachment 1 Field <br /> purge logs are included in Attachment 2 <br /> Groundwater samples were analyzed by State-certified Sequoia Analytical for total purgeable <br /> petroleum hydrocarbons (TPHg) using Environmental Protection Agency (EPA) Method 8015 <br /> modified, total extractable petroleum hydrocarbons (TPHd) using EPA Method 8015 modified, <br /> and benzene, toluene, ethylbenzene, total xylenes (BTEX) and methyl tertiary butyl ether (MTBE) <br /> using EPA Method 8020 Copies of the laboratory reports and chain of custody documentation <br /> are included in Attachment 3 <br /> ANALYTICAL RESULTS <br /> Gioundwater Monitoring Wells <br /> Results of laboratory analyses indicated that dissolved TPHg [2,280 parts per billion (ppb)], <br /> benzene (561 ppb) and TPHd (1,320 ppb) were detected in groundwater well MW-1 Benzene <br /> exceeded the maximum contaminant level (MCL) Low concentrations of toluene, ethyl benzene, <br /> and xylenes were also detected in well MWl but were reported well below the respective MCLs <br /> Low concentrations of TPHd were detected in groundwater wells MW-3, MW-5, and RW-1 <br /> Low concentrations of TPHg and toluene were detected in well RW-1 No other BTEX <br /> constituents were detected in any of the groundwater wells The laboratory results of TPHd were <br /> . reported as unidentified hydrocarbons in the C9-C24 range <br /> W 162574162574 0119436713QSR99doe 2 <br />