ARCHIVED REPORTS -GROUNDWATER MONITORING REPORTS

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i v Ms Lori Duncan Page 2 of 4 between April 1, 2003 and June 30, 2003 was 0 38 feet Approximately 7 9 gallons of product and {� product/water mixture was removed from well MW3 during the reporting period utilizing a passive skimmer and by manually bailing the product from the well A passive skimmer was installed in well MW3 on April 28, 2003 to remove free product 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 a chart showing the measured product thickness in the well over time are included in Attachment A 2.2 Drilling and Installation of Additional Monitoring Wells Ground Zero conducted additional subsurface investigations during the month of May 2003 The investigations included drilling soil borings and installing groundwater monitoring wells southwest (MW5), northeast (MW6), and northwest (MW7) of the former waste oil UST to investigate the extent of groundwater contamination in those directions The monitoring wells were installed in the shallow water bearing zones to total depths of approximately 37-38 feet below ground surface The wells were subsequently surveyed by Morrow Surveying on June 3, 2003 A detailed report summarizing drilling methods and results will be submitted under separate cover 2.3 Groundwater Monitoring Water level elevations were monitored in wells MW1 through MW7 on June 3, 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 Ievel 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 June 3, 2003 ranged from 24 21 feet below the tops of the well casings (btoc) in well MW3 (corrected for the presence of free product) to 25 24 feet btoc in well MW5 Groundwater flowed in a northeasterly direction with a calculated gradient of 0 0034 feet per foot (approximately 18 feet per mile) A potentiometric surface map for June 3, 2003 is shown on Figure 2 Groundwater monitoring data are summarized in Table 2 Monitoring data sheets are included in Attachment B 24 Well Development and Purging An experienced Ground Zero technician developed the new wells (MW5, MW6, MW7) on June 3, 2003 by surging, bailing and pumping each well until turbidity was minimized The temperature, pH, electrical conductivity, and turbidity of the groundwater were measured during the well development process and allowed to stabilize prior to collecting a groundwater sample The wells were developed until turbidity decreased to below 50 NTU Groundwater purged from the wells was placed into labeled DOT approved 55-gallon drums, which were later removed from the site for off-site disposal An experienced Ground Zero technician purged groundwater from wells MW 1, MW2, and MW4 on June 4, 2003 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 0 1GROUNDZOGABBARDIraports\QMR1200312QM2003 doc