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CT"logua[reckwa Iac Page 4 Groundwater Monrtonng Report Project No 770 2 June 15,2004 Vertical gradients were calculated for the MW-5/105 & MW-61106 well pairs for the V quarter 2004 monitoring events The vertical gradient was negative (a downward direction) for the MW-5/105 well pair for all three events The MW-6/106 well pair vertical gradient was positive (an upward direction) on January 22 and February 26, and negative (a downward direction) on December 16 Bothp ositive and negative vertical gradients have been calculated for previous events Similar to the historical lateral directions, the direction of groundwater in the vertical plane also fluctuates at the site The magnitude of vertical groundwater flow direction ranged from—0 02 to 0 0097 for the site investigation 1.2 Groundwater Sampling Procedure On January 22 and February 26, 2004, Del-Tech Geotechnical Support Services staff mobilized to the site to measure depth to groundwater in the site's monitoring wells On March 15 - 16, 2004, Del-Tech Geotechnical Support Services staff again mobilized to the site to complete the quarterly groundwater monitoring and sampling of the site's monitoring wells Before sampling was attempted the wells were sounded for depth to water and then a clear disposable bailer was used to determine if floating product was present No free product was noted for the event, however, the field technician recorded the presence of"sheen/oily droplets" to wells MW-5 and MW-105 The wells were purged of at least three well volumes of stagnant water using a dedicated Waterra check-ball assembly and '/2 inch tubing Purging continued until the temperature, conductivity and pH of the groundwater stabilized (<10% variation among three readings) indicating that formation ' water representative of aquifer conditions was entering the wells These water quality parameters were measured at intervals of each well volume purged ' Once purging was complete, a water sample was collected from the Waterra tube Care was taken to minimize sample agitation Once the sample container was filled and capped, the ' bottle was inverted, tapped and checked for headspace bubbles The sample container was identified and labeled with a unique designation, inserted into foam holders and placed into an ice chest cooled to 4°C for transport to the laboratory ' All non-disposable sampling equipment was decontaminated using a hot water washer and detergent before and between uses Disposable gloves were used by the technician to Icollect all samples and were changed with each sample collection A chain of custody document, listing all samples collected, accompanied the samples from ' field to laboratory, thereby providing a means to track their movement and insure their integrity l 1