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Geo6ytaf7erhnics Inc. Page Sod Groundwater Investigation Report ` C&B Equipment Project No.: 336..2 December 22, 1997 grout (augmented with <4% bentonite) via a tremie tube. The well was secured with a locking watertight cap encased in flush mounted traffic rated well box. On October 20, 1997,Don Light of Del Tech mobilized to the site to developed the new monitoring wells (using mechanical surging and pumping methods) until a clear stream of water was obtained. On October 23, 1997, Don Light returned to the site to purge and collect groundwater samples from the three existing monitoring wells on site, the five new monitoring wells and one domestic well associated with the site. All development and purge water was containerized in 55 gallon DOT approved containers and stored on site until its disposition could be arranged. The groundwater monitoring logs are included in Appendix D. The top of casing elevations for the monitoring wells were surveyed in by Duane Kimball, licensed land surveyor, on December 16, 1997. The elevations are referenced to the U.S.G.S. bench mark"Tracy AZ". A site map with his elevations is included in Appendix E. `= 2.2.1 Groundwater Sampling Procedure The groundwater in the new well was sampled no sooner than 24 hours after well development. The following was the procedure for the sampling of groundwater from the +. well: Before sampling was attempted the well was sounded for depth to water. The wells were then purged of at least 3 well volumes of stagnant water using a submersible pump. Purging continued until the temperature, conductivity, and e H of the groundwater has stabilized p (<10% variation between three readings) indicating that formation water representative of aquifer conditions was entering the well. These water quality parameters were measured at intervals of each well volume purged. A stainless steel bailer was used to collect each sample. Care was taken to minimize sample agitation from the initial filling of the bailer to the transfer of the sample to the VOA vial and glass amber liter bottles. Once the sample container was filled and capped, the bottle was _ then inverted, tapped, and checked for head space bubbles. The sample container was then identified and labeled with a unique designation, inserted into foam holders and placed in an ice chest cooled to VC for transport to the laboratory. All non disposable sampling equipment was decontaminated using a steam cleaner before the following quality control measures: • Disposable gloves were used by the technician to collect all samples and were changed with each sampling event. • A bailer blank for the well was collected prior to sampling by filling the decontaminated - stainless steel bailer with water (provided by the laboratory) and then filling a VOA vial (provided by the laboratory) using the same procedures for actual sample collection. Bailer blanks for each sample, along with a field blank (prepared from water provided by the laboratory poured into a VOA vial on site), accompanied the samples to the laboratory and serve as checks against cross contamination. l .-i i 'i