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Ms Margaret Lagorio <br /> Page 2 of 3 <br /> well casings (btoc) The potentiometric surface rose an average of 0 51 feet since last monitored <br /> on September 6, 2002 Groundwater flowed to the north at a calculated gradient of 0 0043, or <br /> approximately 23 feet per mile A potentiometric surface map for December 3, 2002 is presented <br /> on Figure 2 Groundwater monitoring data are summarized in Table 1 Field notes are included <br /> in Attachment B <br /> Groundwater Sampling <br /> An experienced Ground Zero technician purged and sampled the site wells on December 3, 2002 <br /> The wells were purged of at least five well casing volumes of water using a centrifugal pump <br /> prior to sampling The field technician measured the physical parameters of temperature, pH, <br /> and electrical conductivity during the purging process Purged groundwater was contained in <br /> appropriately labeled DOT-approved 55-gallon drums, which are stored onsite pending disposal <br /> After groundwater parameters had stabilized and water levels had recovered to at least 80% of <br /> pre-purged levels, groundwater samples were collected using dedicated, disposable bailers and <br /> transferred into appropriate containers The samples were then placed into an ice-chest <br /> refrigerated to approximately 4°C and transported to Argon Laboratories (ELAP #2359) under <br /> chain of custody protocol Field notes and purge logs are included in Attachment B <br /> GROUNDWATER ANALYTICAL RESULTS <br /> Argon Laboratories analyzed all groundwater samples for total petroleum hydrocarbons as <br /> gasoline (TPHg) using EPA method 8015M, and for benzene, toluene, ethylbenzene, xylenes <br /> (BTEX), and MTBE using EPA method 8020 <br /> Wells MW1 and MW3 contained TPHg at 810 parts per billion (ppb) and 300 ppb, respectively <br /> Very low levels of toluene, ethylbenzene, and xylenes were also detected in wells MW1 and <br /> MW3 No benzene or MTBE was detected in either well No gasoline constituents were detected <br /> in well MW2 Groundwater analytical results are summarized in Table 2 Laboratory reports are <br /> included in Attachment C <br /> SUMMARY AND CONCLUSIONS <br /> • The depth to groundwater beneath the site ranged from 11 28 to 11 80 feet btoc <br /> Groundwater flowed north with a gradient of approximately 23 feet per mile, <br /> • Very low levels of toluene, ethylbenzene and xylenes were detected in wells MW 1 and MW3 <br /> at levels below their respective primary and secondary Maximum Contaminant Levels <br /> (MCLs), <br /> • No Benzene or MTBE was detected in any site well No gasoline constituents were detected <br /> in well MW2 �. <br /> G 1Data1GROUNDZE\Souza\Reportsl4QMR_2002 dor- <br />