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` v TC A S S O C I A T E S I N C 2.3 Groundwater Monitoring Well Construction Soil borings 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 new wells were surveyed on March 17, 1999 and tied into the existing monitoring wells. Survey data is contained in Table 2. Each well was constructed with 2-inch PVC casing. The screened interval of each well was V 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 MW2 and MW3 were developed on March 17, 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 existing well MW and new wells MW2 and MW3. Fluid levels were taken on March 17, 1999, 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. 2.5 Groundwater Sampling and Anal On March 17, 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 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 .�. Lean clay and lean clay with sand was encountered in soil borings MW2 and MW3 in the upper 6.5 to 10 feet of the soil column. Soil from depths between 6.5 to 10 feet bgs and 16.5 to 20 feet w:\16393\reports\sumi.doc 3 V