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,CvATC A S S O C I A T E S I N C 2.3 Groundwater Monitoring Well Construction 1 Soil borings MW1, MW2, and MW3 were subsequently completed as groundwater monitoring wells to assess impacted groundwater beneath the site, and to provide measurement points for the determination of groundwater flow direction and hydraulic gradient The wells were surveyed on ' February 19, 1999 to an arbitrary elevation Survey data is contained in Table 2 Each well was constructed with 2-inch PVC casing to depths ranging from 38 5 to SFO feet bgs ' The screened interval of each well was positioned from approximately 5 feet above to 15 feet below the encountered water table to allow for seasonal water level fluctuations The screen slot ' size is 0 020-inch Well construction details are depicted on the well logs contained in Appendix A ' 2.4 Monitoring Well Development Groundwater monitoring wells MW1 and MW3 were developed on February 19, 1999 Each well was purged until the extracted water was relatively sediment free Development/purge logs are included in Appendix C Purge water was temporarily stored on site in 55-gallon drums After fluid levels had been allowed to stabilize, groundwater levels were obtained from wells MW1, MW2, and MW3 Fluid levels were taken on February 19, 1999, utilizing an electronic water probe capable of measuring with an accuracy of 11100 of a foot Groundwater elevation data are presented in Table 2 ' 2.5Groundwater Sampling and _._.. p gaAnalysis On February 19, 1999, groundwater samples were collected from wells MW1, MW2, and MW3 The samples were collected after purging a minimum of three well volumes and stabilization of ' electric conductivity, pH, and temperature Field development/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 1 volatilization Sample containers were then labeled with sample identification, placed on ice, and shipped under chain-of-custody to Sequoia Analytical ' The groundwater samples from wells MW1, MW2, and MW3 were analyzed by Sequoia Analytical for TPHg, BTEX, and oxygenate fuel additives Groundwater analytical results are summarized in Table 3, and laboratory data sheets are presented in Appendix D 3.0 SUBSURFACE CONDITIONS ' 3.1 Geology Soil in borings MW1, MW2, and MW3 consisted of silty sand and poorly graded sand from the surface to depths between 16 5 to 20 feet bgs Soil in boring MW1 from depths between 16 5 to w 114981Veportslsumwel doc 3