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Ms Lori Duncan Page 2 of 3 . 2.2 Groundwater Monitoring Water Ievel elevations were monitored in wells MW 1 through MW7 on September 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 September 4, 2003 ranged from 25 20 feet below the top of the well casing (btoc) in well MW3 (corrected for the presence of free product)to 26 20 feet btoc in well MW5 Gioundwater flowed in a northeasterly direction with a calculated gradient of 0 0037 feet per foot (approximately 19 5 feet per mile) A potentiometric surface map for September 4, 2003 is shown on Figuic 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 MW I through MW7 on September 4, 2003 using dedicated, disposable bailers The technician purged a minimum of three well casing volumes of water from each well and measured physical parameteis 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 decontam mated between wells by washing with a solution of laboratory-grade detergent, and then double rinsing with clean i inse water 2.4 Groundwater Sampling Groundwater samples were collected fiom 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 VOCs pursuant to the existing groundwater monitoring and sampling program Field development/pui Ile logs are included in Attachment 2 30 GROUNDWATER ANALYTICAL RESULTS All groundwater samples were analyzed foi VOCs and oxygenated gasoline additives using EPA method 8260B Tetrachloroethene (PCE) was detected in wells MW1, MW2, MW4, MW5, MW6, and MW7 at concentrations of 15 parts per billion (ppb), 8 7 ppb, 8 1 ppb, 6 3 ppb, 48 ppb, and 120 ppb, respectively No PCE was detected in well MW3 (<2 0 ppb) Cis-1,2-dichloroethene (cis-1,2-DCE)ranged from<0 5 ppb in well MW5 to 24 ppb in well MW3 Chloroform ranged from 1 0 ppb in well MW7 to 5 7 ppb in well MW2, but was <20 ppb in well MW3 Tiichloroethene (TCE) was detected in wells MW1, MW2, MW3, MW6, and MW7, ranging from 0 5 ppb in we]I MW2 to 6 5 ppb in well MW7 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 benzene at 32 ppb, toluene at 95 ppb, ethylbenzene at 37 ppb, and xylenes at 190 ppb Well MW3 also contained several additional VOCs including 1,4-dichlorobenzene at 6 5 ppb GIGROUNDZE\GABBARDIreports\QMR\2003\3QM2003 doc