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'eologtca!'IecF�cus Inc Page 4 Soil& Groundwater Investigation Report Ted Peters-UST Project No 640 2 November 3, 1999 ' On July 23, 1999, Don Light of Del Tech mobilized to the site to develop the new monitoring wells (using mechanical surging and pumping methods) until a clear stream of water was obtained On July 26, 1999, Don Light returned to the site to purge and collect groundwater ' samples from the three new monitoring wells All development and purge water was containerized in 55-gallon DOT approved containers and stored on site until its disposition can be arranged ' 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 centrifugal pump Purging continued until the temperature, conductivity, and pH of the groundwater has stabilized (<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 a sample from each well Care was taken to I 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 headspace 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 4°C for transport to the laboratory All non-disposable sampling equipment was decontaminated using a steam cleaner before I and between uses Disposable gloves were used by the technician to collect all samples and were changed after each sample was collected I 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 IAll water purged from each monitoring well was placed in a 55 gallon DOT approved container, properly labeled and stored on site 2.2.2 Groundwater Sample Analyses One groundwater sample from each well was submitted to BSK Laboratories of Fresno (State Certified Laboratory 41180) and analyzed for a benzene, toluene, ethylbenzene and xylene (BTEX) by EPA method 602 a oxygenated fuel compounds (MTBE, DIPE, ETBE, TAME, TBA by EPA method 8260 a gasoline range petroleum hydrocarbons (TPH-G) by EPA method 8015(m) A Chain of Custody was completed for all samples collected and tracked to ensure sample integrity I