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� v A A S S O C I A T E S I N C 4.7 Groundwater Monitoring Well Construction ' Soil borings MW8 through MW10 were completed as groundwater monitoring g wells to assess ' impacted groundwater beneath the site, and to provide measurement points for the determination of groundwater flow direction and hydraulic gradient ' The groundwater wells were constructed with 2-inch PVC casing to a depth of approximately 40 feet bgs The screen interval in the groundwater wells was positioned with approximately 5 feet of screen above and 15 feet of screen below the encountered water table to allow for seasonal water level fluctuations The screen slot size was 0 020-inch All on-site and off-site wells were surveyed on March 8, 2002 by a State-licensed land surveyor, ' Condor Earth Technologies (47698) The wells were surveyed to NAD83 horizontal datum and NAVD88 vertical datum The equipment used to survey the wells to the horizontal datum was a Leica GPS 500 sub-centimeter level GPS system in RTK mode The equipment used to survey ' the wells to the vertical datum was a Topcon Auto-Level optical level Survey data are presented in Table 3 4.8 Monitoring Well Development ' Groundwater monitoring wells MW8 through MW10 were developed on December 31, 2001 Each well was purged until the extracted water was relatively sediment free Development logs are included in Appendix D Purgewater was temporarily stored on site in DOT approved 55- gallon drums 4.9 Groundwater Sampling and Analysis ' On December 31, 2001, groundwater samples were collected from groundwater wells MW1 through MW10 and CW On December 31, 2001, fluid levels were taken 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 D Subsequent to purging, groundwater was sampled and transferred to appropriate sample containers, using clean, disposable bailers with bottom emptying devices to reduce volatilization ' Groundwater lace were samples d on ice and delivered under chain-of-custody p p y documentation to Argon for chemical analysis Selected groundwater samples were analyzed for TPHg by EPA method 8015, BTEX by EPA method 8020, and MTBE, TAME, ETBE, DIPE, TBA, 1,2-DCA, and EDB by EPA method 8260 The analytical results for groundwater samples are summarized in Table 2 Laboratory data sheets and chain-of-custody documentation are included in Appendix C ' w lwordpro\625961reportsloff--site doc 6