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r I I i ' Ms Margaret Lagono Page 2 of 6 GROUNDWATER ACTIVITIES -� Groundwater Monitoring and Sampling r� Groundwater monitoring was conducted on November 20, 2000 Depth to groundwater was i ' measured in wells MW 1 through MW 13 and subtracted from the wellhead elevations to determine groundwater elevation The depth to groundwater was also measured in vapor wells VW1 through VW6, however, wellhead elevations have not been determined for the vapor wells Water levels fell an average of 1 16 feet since last monitored on August 14, 2000 Groundwater flow direction was generally towards the northeast with a gradient averaging approximately 0 004 feet per foot A groundwater gradient map generated using the November 20, 2000 monitoring ' data is shown on Figure 2 Groundwater monitoring data are summarized in Table 1 Monitoring logs and well construction information are included in Attachment A ' On November 20, 2000 through November 22, 2000, Ground Zero collected groundwater samples from groundwater monitoring wells MW 1 through MW 13, and vapor wells VW 1 through VW6 A nummum of three well casing volumes was purged from each well prior to ' sampling During the purging process, physical parameters (pH, conductivity, and temperature) were monitored in each well and allowed to stabilize before collecting groundwater samples Samples were collected after groundwater recharged to 100% of the original depth to water level Purged water was contained in labeled 55-gallon drums approved by the Department of Transportation (DOT) The drums are stored onsite in a locked enclosure Purge logs and purgewater disposal documentation is included in Attachment A Samples collected for analysis were placed in an ice chest at a temperature of approximately 4° ' Centigrade, and transported under chain of custody to Argon Laboratories (FLAP #2359) TPHg and BTEX were analyzed using EPA method 8015 modified and EPA method 8020, respectively Oxygenates, EDB, 1,2 DCA, methanol and ethanol were analyzed using EPA method 8260 ' Analytical results for TPHg, BTEX and MTBE are summarized in Table 2, oxygenate results are summarized in Table 3 Attachment B contains laboratory reports and chain of custody documentation ' Groundwater Analytical Results ' Groundwater Monitoring Wells The potentiometric surface was above the top of the screened intervals in all monitoring wells except MW 1, MW2, and MW 13 No petroleum hydrocarbons were detected in wells MW 11 and ' MW 12 Low levels of petroleum hydrocarbons were detected in wells MW2, MW7, MW9 and MW10 after being at non-detectable levels during the last event The highest concentrations of TPHg and BTEX were detected ,n samples collected from wells MW3, MW4, MWS, and MW 13 TPHg and benzene were at their highest concentrations in well MW3 since sampling began TPHg increased an order of magnitude in wells MW3 and MW 13, and benzene concentrations ' roeklq=\4QM2000