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eel A S S O C I A T E S I N C 2_4 Monitoring Well Development Groundwater monitoring wells MWI, MW2, and MW3 were developed on November 27, 2001. Each well was purged until the extracted water was relatively sediment free. Development logs are included in Appendix C. Purgewater was temporarily stored on site in 55-gallon drums. 225 Groundwater Sampling and Analysis On November 27, 2001, groundwater samples were collected from wells MW I, MW2, and MW3. Fluid levels were taken on November 27, 2001, utilizing.an electronic water probe capable of ' measuring with an accuracy of 1/100 of a foot. Groundwater elevation data are presented in Table 2. The samples were collected after purging a minimum of three well `volumes and stabilization of electric conductivity, pH, and temperature. Field purge logs are presented in ' Appendix C. Subsequent to purging, groundwater was sampled and transferred to appropriate sample containers, using clean, disposable bailers with bottom emptying devices to reduce volatilization. ' Groundwater samples were placed on ice and delivered under chain-of-custody documentation to Argon Laboratories for chemical analysis. Groundwater samples were analyzed for TPHg by EPA method 8015 modified; BTEX by EPA method 8020; and MTBE, TAME, TBA, ETBE, DIPE, 1,2-DCA, and EDB by EPA method 8260. The analytical results for groundwater samples are summarized in Table 3. Laboratory data sheets and chain-of-custody documentation are included ' in Appendix D. 3.0 SUBSURFACE CONDITIONS 31 Geolory Soil from the borings generally consisted of silts and sandy silts from the surface to 22 to 30 feet bgs. Soil consisted of silty sand and sand from depths between 22 to 30 feet bgs and 27 to 35 feet bgs. Soil consisted of clayey sand, sandy clay and clay from depths between 27 to 35 feet bgs and 29 to 42 feet bgs. Soil consisted of silts and sandy silts from depths between 29 to 42 feet bgs and 56.5 feet bgs, the maximum depth explored in these borings. Soil boring logs with a detailed ' description of soil types are contained in Appendix A. 3.2 Hydrogeology ' Water level measurements were collected from wells MW1 through MW3 on November 27 g , 2001. Water levels ranged from 42.38 to 43.27 feet below the tops of the well casing elevations. The water level data were used to develop the groundwater elevation contour map (Figure 3). ,+ Assuming that horizontal isotropic conditions prevail, groundwater in the uppermost aquifer beneath the site flowed towards the north. The average hydraulic gradient on November 27, 2001 ,\92054.0001Vt"Aslsumii.doe 4