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r1�2 fL Ms Lori Duncan Page 2 of 3 22 Groundwater Monitoring Water Ievel elevations were monitored in wells MW 1 through MW7 on December 4, 2003 The depth to water and depth to product in well MW3 were measured using an electronic water/hydrocarbon interface probe Depths to water in other site wells were measured using an electronic water level indicator Groundwater elevations were calculated by subtracting the measured depth to groundwater in each well from the respective wellhead elevation The depth to groundwater in the wells on December 4, 2003 ranged from 25 97 feet below the top of the well casing (btoc) in well MW3 to 27 02 feet btoc in well MW5 Groundwater flowed in a northeasterly direction with a calculated gradient of 0 0035 feet per foot (approximately 18 5 feet per mile) A potentiometric surface map for Dece 4, 2003 is shown on Figure 2 Groundwater monitoring data are summarized in Table 2 Monitoring data sheets are included in Attachment 2 2.3 Well Purging An experienced Ground Zero technician purged wells MW1 through MW7 on December 4, 2003 using dedicated, disposable bailers The technician purged a minimum of three well casing volumes of water from each well and measured physical parameters of temperature, pH and electrical conductivity during the purging process Purging was terminated at each well after the measured parameters stabilized All downhole equipment was decontaminated between wells by washing with a solution of laboratory-grade detergent, and then double rinsing with clean rinse water 2.4 Groundwater Sampling Groundwater samples were collected from each well after physical parameters had stabilized and the water in the well had recovered to at least 80% of pre-purge levels Samples were placed in an ice chest at a temperature of 4° Centigrade and submitted to Argon Laboratory under chain of custody protocol The samples were analyzed for the presence of TPHg, TPHd, BTEX, and VOCs pursuant to the existing groundwater monitoring and sampling program Field development/purge logs are included in Attachment 2 3.0 GROUNDWATER ANALYTICAL RESULTS All groundwater samples were analyzed for TPHg and TPHd using EPA method 8015B, BTEX using EPA 8021 B, and VOCs and oxygenated gasoline additives using EPA 8260B Tetrachloroethene (PCE) was detected in wells MW1, MW2, MW4, MW5, MW7, and MW7 at concentrations of 12 parts per billion (ppb), 9 4 ppb, 7 4 ppb, 5 0 ppb, 34 ppb, and 77 ppb, respectively No PCE was detected in well MW3 (<20 ppb) Cis-1,2-dichloroethene (cis-1,2-DCE) ranged from <0 5 ppb in well MW5 to l9 ppb m well MW3 Chloroform ranged from 13 ppb in well MW5 to 4 2 ppb in well MW 1, but was not detected in well MW3 at a detection limit of 2 0 ppb Trichloroethene (TCE) was detected in wells MWI, MW2, MW3, MW6, and MW7, ranging from 0 7 ppb in well MW2 to 5 8 ppb in well MW3 No petroleum hydrocarbons or gasoline additives were detected above method detection limits in groundwater samples collected from any site well, except well MW3 Well MW3 contained TPHg at 1,600 ppb, benzene at 14 ppb, toluene at 39 ppb, ethylbenzene at 18 ppb, and xylenes at 86 ppb Well MW3 also contained several additional VOCs GIGROUNDZEIGABBARDIreports\QMR1200314QM2003 doe