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Mr Jeff Wong Page 2 of 4 2.2 Groundwater Monitoring and Sampling A Ground Zero technician monitored water levels in all site wells, and collected groundwater samples from monitoring wells MW2 through MW913 on September 10 and 11, 2003 No sample was collected from well MWI Groundwater elevations were calculated by measuring the depth to groundwater in each well and subtracting the measured depth from the respective well head elevation The measured depth to groundwater below the tops of the well casings (btoc) in the shallow monitoring wells ranged from 67 38 feet in well MW1 (corrected for the presence of free product) to 68 24 feet in well MW5 (completed at approximately 2 25 feet above ground surface) Groundwater elevations in the shallow aquifer beneath the site ranged from 35 39 feet below mean sea level (MW2) to 35 80 feet below mean sea level (MW5) Groundwater levels in shallow monitoring wells MW1 through MWS fell an average of 3 89 feet between June 17, 2003 and September 10, 2003 The groundwater level in well MW9B, which was completed in a deeper aquifer, was measured at approximately 67 78 feet btoc on September 10, 2003, a drop of 3 95 feet during the same period Table 2 summarizes groundwater elevations in site monitoring wells Groundwater flow in the shallow aquifer was irregular beneath the site on September 10, 2003, but was generally toward the northeast Figure 2 presents a potentiometrxc surface map generated using the September 10, 2003 monitoring data An experienced Ground Zero technician purged at least three well casing volumes of water from monitoring wells MW i through MW9B prior to sampling the wells During the purging process, the technician measured the temperature, pH and electrical conductivity of the water Samples were collected after the physical parameters stabilized and water levels in the wells recovered to at least 80% of their pre-purged levels The samples were temporarily stored in an ice chest refrigerated to a temperature of approximately 4°C and delivered under chain of custody protocol to Argon • Laboratories (FLAP #2359) for analysis Purged groundwater was contained in appropriately labeled DOT-approved 55-gallon drums in accordance with 49 CFR part 172 and 40 CFR part 262 Copies of field data sheets and purge logs are included in Attachment B 3.4 GROUNDWATER ANALYTICAL RESULTS Argon Laboratories analyzed all groundwater samples total petroleum hydrocarbons as gasoline (TPHg) using EPA 8015B, benzene, toluene, ethylbenzene, and total xylenes (BTEX) using EPA 8021B, and oxygenated gasoline additives, ethylene dibromide (EDB) and 1,2-dichloroethane (1,2- DCA)using EPA 8260B No gasoline constituents were detected in groundwater samples collected from wells MW6, MW7, MW8, or MW913 .} TPHg was detected in wells MW2 and MW4 at concentrations of 1,700 parts per billion(ppb) and 100 G IGROUNDZEITULESURG\ReportslQMR1200313QM2003 doc