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Well Purging <br /> Before sampling occurred, a polyvinyl chloride (PVC) bailer, centrifugal pump, low-flow <br /> submersible pump, or Teflon bailer was used to purge standing water in the casing and <br /> gravel pack from the monitoring well Monitoring wells were purged according to the <br /> Protocol presented in Figure A-I In most monitoring wells, the amount of water purged <br /> before sampling was greater than or equal to three casing volumes Some monitoring wells <br /> were expected to be evacuated to dryness after removing fewer than three casing volumes <br /> These low-yield monitoring wells were allowed to recharge for up to 24 hours Samples <br /> were obtained as soon as the monitoring wells recharged to a level sufficient for sample <br /> collection If insufficient water recharged after 24 hours, the monitoring well was recorded <br /> as dry for the sampling event <br /> Groundwater purged from the monitoring wells was transported in a 500-gallon water <br /> trailer, 55-gallon drum, or a 325-gallon truck-mounted tank to EMCON's San Jose or <br /> Sacramento office location for temporary storage EMCON arranged for transport and <br /> disposal of the purged groundwater through Integrated Waste Stream Management, Inc, <br /> Field measurements of pH, specific conductance, and temperature were recorded in a <br /> waterproof field logbook Figure A-2 shows an example of the water sample field data <br /> sheet on which field data are recorded Field data sheets were reviewed for completeness <br /> by the sampling coordinator after the sampling event was completed <br /> The pH, specific conductance, and temperature meter were calibrated each day before <br /> field activities were begun The calibration was checked once each day to verify meter <br /> performance Field meter calibrations were recorded on the water sample field data sheet <br /> Well Sampling <br /> A Teflon bailer was the only equipment acceptable for well sampling When samples for <br /> volatile organic analysis were being collected, the flow of groundwater from the bailer was <br /> regulated to minimize turbulence and aeration Glass bottles of at least 40-rrullihters <br /> volume and fitted with Teflon-lined septa were used in sampling for volatile organics <br /> These bottles were filled completely to prevent air from remaining in the bottle A positive <br /> meniscus formed when the bottle was completely full A convex Teflon septum was placed <br /> over the positive meniscus to eliminate air After the bottle was capped, it was inverted <br /> and tapped to verify that it contained no air bubbles The sample containers for other <br /> parameters were filled, filtered as required, and capped <br /> When required, dissolved concentrations of metals were determined using appropriate <br /> field filtration techniques The sarnple was filtered by emptying the contents of the Teflon <br /> bailer into a pressure transfer vessel A disposable 0 45-micron acrylic copolymer filter <br /> was threaded onto the transfer vessel at the discharge point, and the vessel was sealed <br /> Pressure was applied to the vessel with a hand pump and the filtrate directed into the <br /> is appropriate containers Each filter was used once and discarded <br /> SACW\P1ft8OW8051510 2AS Wcjb 1 A-3 Rev 0 September 24 1996 <br />