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The current groundwater elevation, approximately 7 5 feet below the top of the well casings, is above the top of the screen, approximately 8 to 10 feet below the top of the well casings Because of the extremely high groundwater elevation, the petroleum hydrocarbon concentrations in groundwater at this time are representative of the screen interval and not the groundwater table Groundwater beneath the site generally flows in a southwesterly direction with average gradient of 0 002 ft/ft, or approximately 10 6 feet/mile Groundwater monitoring data are summarized in Table 1 A groundwater gradient map for the June 25, 1997 monitoring episode is shown on Figure 2 Groundwater samples were collected from wells MW2 through MW4 after purging and stabilization of physical parameters (pH, electrical conductivity, and temperature) The monitoring wells were purged and sampled according to RESNA Industries Quality Assurance/Quality Control Plan, on file with PHS/EHD Well purge logs are included in Attachment 1 The community well was sampled through an existing sampling port Collected groundwater samples were placed on ice and transported under chain-of-custody to State-certified Argon Laboratories Samples were analyzed for benzene, toluene, ethylbenzene, and xylenes (BTEX) and TPHg by EPA methods 8020 and modified 8015, respectively Laboratory analyses detected elevated concentrations of petroleum hydrocarbons in the samples collected from wells MW3 and MW4 Groundwater samples collected from well MM2 and the municipal well contained no detectable concentrations of BTEX or TPHg The laboratory method detection levels for BTEX and TPHg were 0 5 and 50 ppb, respectively The analytical iresults are generally consistent with historical levels Analytical results are summarized in Table 1 Laboratory reports and chain-of-custody documentation are presented in Attachment 2 In accordance with PHS/EHD correspondence dated December 27, 1993, the sampling schedule of MW 1 has been reduced to annually and wells MW5 and MW6 to semi-annually Wells MW2, MW3 and MW4 will continue to be sampled quarterly Additionally, the nearby community well will be sampled quarterly This schedule is based upon historical groundwater analytical data w 1943261quart1y12gr-1997 doc 3 • SMTH