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C7eo(ogico,rech"tcs lr[e Page 4 Groundwater Monitoi ing Report Project No 770 2 September 24, 2043 Both positive 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 fiom—0 02 to 0 0097 for the site investigation ' 1.2 Groundwater Sampling Procedure On April 28 and May 23, 2003, Del-Tech Geotechnical Support Services staff mobilized to the site to measure depth to groundwater in the site's monitoring wells On June 18, 2003, Don Light of Del-Tech Geotechnical Support Services 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 detennine if floating product was present No free product was noted for the event however well MW-5 contained product sheen The wells were purged of at least three well volumes of stagnant water using a dedicated Waterra check-ball assembly and %Z inch tubing Purging continued until the temperature, conductivity and pH of the groundwater stabilized (C10% variation among three readings) indicating that formation water representative of aquifer conditions was entering the wells These water quality parameters weie measuied 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 ' collect 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 ' All water purged from each monitoring well and not used as a sample was placed in a properly labeled 55 gallon DOT approved container and stored on site until its proper disposition can be arranged ' Groundwater monitoring g field logs are included in Appendix C pp