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Ms Lori Duncan Page 2 of 3 The waste was stored on site in accordance with 49 CFR part 172 and 40 CFR part 262 Table 1 summarizes product thickness measurements and product removed Field notes associated with product bailing, including charts showing the measured product thickness in the well over time and the depth to fluid thickness in the well over time are included in Attachment 1 2.2 Groundwater Monitoring Water level elevations were monitored in wells MW1 through MW7 on September 30, 2004 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 30, 2004 ranged from 26 35 feet below the top of the well casing (btoc) in well MW3 (corrected for the presence of free product) to 27 31 feet btoc in well MW5 Groundwater flowed in a northeasterly direction with a calculated gradient of 0 0041 feet per foot (approximately 21 feet per mile) A potentiometric surface map for September 30, 2004 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 September 30, 2004 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 pre-purged 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/purge logs are included in Attachment 2 3.0 GROUNDWATER ANALYTICAL RESULTS Tetrachloroethene (ACE) was detected in wells MW1, MW2, MW4, MW5, MW6, and MW7 at concentrations of 8 6 parts per billion (ppb), 7 9 PPba 3 8 ppb, 4 4 ppb, 45 Ppb, and 110 ppb, respectively Y No PCE was detected in well MW3 (<0 5 ppb) cis-1,2-Dichloroethene(cis-1,2-DCE)ranged from <0 5 ppb in wells MW2, MW4 and MW5 to 7 7 ppb in well MW3 Chloroform ranged from 0 7 ppb in wells MW4 and MW7 to 2 2 ppb in well MW6, but was not detected in well MW3 (<0 5 ppb) Trichloroethene (TCE) was detected only in wells MW6 (1 5 ppb) and MW7 (3 6 ppb) •} 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 5 6 G\GROUNDZEIGABBARDVeportslQMR12004L3QM2004 doe