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Mr Mike Infurna . Page 2 collected after physical parameter stabilization, and a minimum of 80% recovery of pre purge water levels Subsequently the samples were placed in an ice chest refrigerated to a temperature of approximately 4°C Purgewater was contained m appropriately labeled DOT-approved 55-gallon drums Purge logs are included in Attachment A Groundwater samples were delivered under chain of custody protocol to Argon Laboratories (ELAP #2359) Analysis consisted of gasoline oxygenate additives, 1,2-DCA and EDB using EPA method 8260, BTEX using EPA method 8 02 0, and TPHg using modified EPA method 8015 I GROUNDWATER ANALYTICAL RESULTS Gasoline oxygenate additives and EDB were not detected in the samples from any monitoring well TPHg and benzene were detected wells MWl through MW4 and in U-Haul well MW7 Concentrations of dissolved TPHg and benzene ranged from 480 parts per billion (ppb) to 220,000 ppb, and 2 0 ppb to 17,000 ppb in wells MW3 and MWl, respectively 1,2-DCA detected in groundwater ranged from 260 ppb in well MW2 to 1,200 ppb in well MW1 1,2-DCA was not detected in MW3 nor in U-Haul well MW7 Analytical results are summarized in Table 2 Attachment B contains laboratory reports and chain of custody documentation SUNEVIARY The groundwater gradient at the site was flat(;z0 001 ft/ft or—_5 ft/mi) Groundwater appeared to flow in a northwesterly direction Concentrations of TPHg, BTEX and 1,2-DCA were similar to those measured during previous sampling events Concentrations of gasoline oxygenate additives and EDB remained below laboratory method detection limits in all wells, and 1,2 DCA was not detected in wells MW3 and U-Haul MW7 CONCLUSIONS • Groundwater flow direction at the site continues to exhibit extreme variability This variability may be a result of the pumping of nearby water supply wells Water levels at the site fell nearly six feet since the previous sampling event Water levels in the site vicinity exhibit large seasonal fluctuations and even larger long-term fluctuations • Overall concentrations of dissolved petroleum hydrocarbons and 1,2-DCA in groundwater at the site appear to be stable or slowly decreasing • The limits of the dissolved hydrocarbon plume have not been defined RECOMMENDATIONS We recommend the installation of additional monitoring wells as proposed in our Workplan dated June 28, �. 2002 In response to the first comment in the EHD Workplan approval letter (July 15, 2002), we will install a deep monitoring well in the central portion of the site and will screen the well from approximately 95-100 feet 11GZA FS%SY5011Data1GROLINDZEV ARRYSaeports\QMR1200212QM2002 doe