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i <br /> 3.2 GROUNDWATER SAMPLING <br /> ;..,.�� On December 2, 199$ groundwater samples were collected from monitoring wells MW-1 <br /> through MW-12, VW-1, and VW-2. Prior to the collection of groundwater samples, the <br /> -� monitoring wells were purged of a minimum of three well volumes of water and until pH, <br /> ' conductivity, and temperature stabilized. The wells were allowed to recover to at least 80 <br /> percent of their original static groundwater levels prior to sampling. <br /> The following procedures were implemented for well monitoring, well purging, and water <br /> sampling. <br /> r' 1. All equipment was washed prior to entering the well with an Alconox solution, <br /> followed by two tap water rinses and a deionized water rinse. <br /> _=l <br /> 2. Prior to purging the wells, depth-to-water was measured using an Solinst <br /> groundwater interface probe to an accuracy of approximately 0.01 foot. The <br /> measurements were made to the top of the well casing on the north side. <br /> 3. Monitoring wells at the site were prepared for sampling by purging the well of <br /> approximately three well volumes of water using a submersible pump or polyvinyl <br /> chloride (PVC) bailer. <br /> 4. Water samples were collected with a single-use Teflon bailer after the well had <br /> been purged and water in the well had equilibrated to approximately 80 percent of <br /> the static water level or 2 hours after well purging, whichever occurred first. The <br /> water collected was immediately decanted into laboratory-supplied vials and <br /> bottles. The containers were overfilled, capped, labeled, and placed in a chilled <br /> cooler prior to delivery to the laboratory for analysis. <br /> 5. Chain-of-custody procedures, including chain-of-custody forms, were used to <br /> document water sample handling and transport from collection to delivery to the <br /> ` .l laboratory for analyses. <br /> l-m; <br /> .'�1 <br /> 6. Groundwater samples were delivered to the State-certified hazardous waste <br /> laboratory within approximately 48-hours of collection. <br /> 7. Purged water was contained in a DOT approved 55-gallon drum. The drum was <br /> labeled with the contents, date, well number, client name, and project number. <br /> The groundwater monitoring purge logs are presented in Appendix A. <br /> t ,71 <br /> f <br /> i F:Transfer\Report\CALTRANS\Calty0s7171017\STOCKTON\gm49Bf#n 2 <br />