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Ms Margaret Lagono Page 2 of 3 (bgs) The potentiometric surface rose an average of 0 29 feet between November 27, 2001 and June 11, 2002 Groundwater flowed to the north at a calculated gradient of 0 0034 ft/ft, or approximately 18 ft/mile A potentiometric surface map for June 11, 2002 is presented on Figure 2 Groundwater monitoring data are summarized in Table 1 Field notes are included in Attachment B Groundwater Sampling An experienced Ground Zero technician purged and sampled the site wells on June 11, 2002 The wells were purged of at least three well casing volumes of water using a centrifugal pump prior to sampling The field technician measured the physical parameters of temperature, pH, and electrical conductivity during the purging process Purged groundwater was contained in appropriately labeled DOT-approved 55-gallon drums The drums are currently being stored onsite pending disposal After groundwater parameters had stabilized and water levels had recovered to at least 80% of pre-purged levels, groundwater samples were collected using dedicated, disposable bailers and transferred into appropriate containers The samples were then placed into an ice-chest refrigerated to approximately 4°C and transported to Argon Laboratories (FLAP ##2359)under chain of custody protocol Field notes and purge logs are included in Attachment A. GROUNDWATER ANALYTICAL RESULTS Argon Laboratories analyzed all groundwater samples for total petroleum hydrocarbons as gasoline (TPHg), total petroleum hydrocarbons as diesel (TPHd), and total petroleum hydrocarbons as kerosene (TPHk) using EPA method 8015M, benzene, toluene, ethylbenzene, and xylenes (BTEX) using EPA method 8020, and oxygenated gasoline additives, 1,2-DCA, and EDB using EPA method 8260B No TPHd, TPHk, oxygenated gasoline additives, EDB, or 1,2-DCA was detected in any site well TPHg was detected in wells MW1, MW2 and MW3 at concentrations of 530 parts per billion (ppb), 85 ppb and 1,900 ppb, respectively Benzene was detected in wells MW1 and MW3 at 1 4 ppb and 3 6 ppb, respectively Ethylbenzene and xylenes were also detected at low levels in wells MW l and MW3 Toluene was detected only in well MW3 No BTEX was detected in well MW2 Groundwater analytical results are summarized in Table 2 Laboratory reports are included in Attachment C SUMMARY • Groundwater elevations beneath the site rose slightly between November 2001 and June 2002 Groundwater beneath the site flows toward the north at a relatively mild gradient • No TPHd, TPHk, oxygenated gasoline constituents, EDB, or 1,2-DCA was detected in any site well for the second consecutive sampling event • Gasoline constituents were detected in each of the three site wells Gasoline constituents generally decreased slightly in wells MW 1 and MW2, but increased slightly in well MW3 TPHg was the only constituent of concern detected in well MW2 G%Data\GRC)UNDZE\Souza\Reportsl2QMR 2002 doc