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l >ti 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 samples from monitoring wells MW2 through MW9B on March 12 and 13, 2003 No sample was collected from well MW 1 due to the presence of free product 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 63 42 feet in well MW 1 (corrected for the presence of free product) to 64 20 feet in well MW5 (completed at approximately 2 25 feet above ground surface) Groundwater elevations in the shallow aquifer beneath the site ranged from 31 55 feet (MW6) to 31 76 feet (MW7) below mean sea level Groundwater levels in shallow monitoring wells MW1 through MW8 rose an average of 0 72 feet between December 11, 2002 and March 12, 2003 The groundwater level in well MW913, which was completed in a deeper aquifer, was measured at approximately 63 36 feet btoc on March 12, 2003, and rose 0 80 feet during the same period Table 2 summarizes groundwater elevations in site monitoring wells The measured groundwater flow direction in the shallow aquifer was irregular beneath the site on March 12, 2003 The groundwater gradient across the site averaged approximately 0 0015 feet per foot (approximately 8 feet per mile) Figure 2 presents a potentnometrnc surface map generated using the March 12, 2003 monitoring data An experienced Ground Zero technician purged at least three well casing volumes of water from monitoring wells MW2 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 2.3 Liquid Waste Disposal On March 18, 2003, American Valley Waste Oil, Inc (CAL000827878) removed and transported approximately 300 gallons of purgewater generated from groundwater monitoring activities to a permitted disposal/recycling facility A copy of the non-hazardous waste manifest is included in Attachment C 3.0 GROUNDWATER ANALYTICAL RESULTS Argon Laboratories analyzed the groundwater samples for total petroleum hydrocarbons as gasoline (TPHg) using EPA 8015M, benzene, toluene, ethylbenzene, and total xylenes (BTEX) using EPA 8020, and oxygenated gasoline additives, ethylene dnbromnde (EDB) and 1,2-dnchloroethane (1,2- DCA)using EPA 8260B Well MWl was not sampled due to the presence of free product 6 1GROUNDZEITULEBURG\Reports\QMR\2003\1QM2003 doc