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Z Well Purging If the depth to groundwater was above the top of screens of the monitoring wells, then the wells were purged Before sampling occurred, a polyvinyl chloride (PVC) bailer, centrifugal pump, low -flow submersible pump, or Teflon bailer was used to purge standing water in the casing and gravel pack from the monitoring well Monitoring wells were purged according to the protocol presented in Figure A-1 In most monitoring wells, the amount of water purged before sampling was greater than or equal to three casing volumes Some monitoring wells were expected to be evacuated to dryness after removing fewer than three casing volumes These low -yield monitoring wells were allowed to recharge for up to 24 hours Samples were obtained as soon as the monitoring wells recharged to a level sufficient for sample collection if insufficient water recharged after 24 hours, the monitoring well was recorded as dry for the sampling event Groundwater purged from the monitoring wells was transported in a 500 -gallon water trailer, 55 -gallon drum, or a 325 -gallon truck -mounted tank, to IT's San Jose or Sacramento office location for temporary storage IT arranged for transport and disposal of the purged groundwater through Integrated Waste Stream Management, Inc Field measurements of pH, specific conductance, and temperature were recorded in a waterproof field logbook Figure A-2 shows an example of the water sample field data sheet on which field data are recorded Field data sheets were reviewed for completeness by the sampling coordinator after the sampling event was completed The pH, specific conductance, and temperature meter were calibrated each day before field activities were begun The calibration was checked once each day to verify meter performance Field meter calibrations were recorded on the water sample field data sheet Well Sampling A Teflon bailer was the only equipment acceptable for well sampling When samples for volatile organic analysis were being collected, the flow of groundwater from the bailer was regulated to minimize turbulence and aeration Glass bottles of at least 40 -milliliters volume and fitted with Teflon -lined septa were used in sampling for volatile organics These bottles were tilled completely to prevent air from remaining in the bottle A positive meniscus formed when the bottle was completely full A convex Teflon septum was placed over the positive meniscus to eliminate air After the bottle was capped, it was inverted and tapped to verify that it contained no air bubbles The sample containers for other parameters were filled, filtered as required, and capped When required, dissolved concentrations of metals were determined using appropriate field filtration techniques The sample was filtered by emptying the contents of the Teflon bailer into a pressure transfer vessel A disposable 0 45 -micron acrylic copolymer filter was threaded onto the transfer vessel at the discharge point, and the vessel was sealed Pressure was applied to the vessel with a hand pump and the filtrate directed into the appropriate containers Each filter was used once and discarded CP 1C\Common\QMR\ARCO\4thO99\2168Q499 DOC-98Ug 1 IT Corpomtjon A-3 02/07/00