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3 2 GROUNDWATER SAMPLING On May 27, 28, and 29, 1997, groundwater samples were collected from monitoring wells ' MW-1 through MW-12, VW-1, and VW-2 Prior to the collection of groundwater samples, the monitoring wells were purged of a minimum of three well volumes of water and until pH, conductivity, and temperature stabilized The wells were allowed to recover to at ' least 80 percent of their original static groundwater levels prior to sampling The following are procedures for well monitoring, well purging, and water sampling 1 All equipment was washed prior to entering the well with an Alconox solution, followed by two tap water rinses and a deionized water rinse ' 2 Prior to purging the wells, depth-to-water was measured using an Solinst groundwater interface probe to an accuracy of approximately 0 01 foot The ' measurements were made to the top of the well casing on the north side 3 Monitoring wells at the site were prepared for sampling by purging the well of ' approximately 3 well volumes of water using a 2-inch or 4-inch diameter polyvinyl chloride (PVC) bailer 4 One well volume was calculated using the following equation ' V = 314x7481 xhr12 where V = one well volume h = (d,-d2) r1 = the radius of the well in feet 5 Water samples were collected with a Teflon bailer after the well had been purged and water in the well had equilibrated to approximately 80 percent of the static water level or for 2 hours, whichever occurred first The water collected was ' immediately decanted into laboratory-supplied vials and bottles The containers were overfilled, capped, labeled, and placed in a chilled cooler prior to delivery to the laboratory for analysis 6 Chain-of-custody procedures, including chain-of-custody forms, were used to document water sample handling and transport from collection to delivery to the Ilaboratory for analyses 2 F TransfeAReporl\CALTRANS\Ce11y087171017\gm297 fin