Laserfiche WebLink
f <br /> s <br /> 1.41 <br /> Well Purging <br /> If the depth to groundwater is above the top of screens of the monitoring wells, then the <br /> wells will be purged. Before sampling occurs, a polyvinyl chloride (PVC) hailer, <br /> centrifugal pump, low-flow submersible pump, or Teflon bailer will be used to purge <br /> standing water in the casing and gravel pack from the monitoring well. In most <br /> monitoring wells, the amount of water purged before sampling is greater than or equal to <br /> three casing volumes. Some monitoring wells are expected to be evacuated to dryness <br /> after removing fewer than three casing volumes. These low-yield monitoring wells will <br /> be allowed to recharge for up to 24 hours. Samples will be obtained as soon as the <br /> monitoring wells recharged to a level sufficient for sample collection. If insufficient water <br /> recharged after 24 hours, the monitoring well will be recorded as dry for the sampling <br /> event. <br /> Groundwater purged from the monitoring wells will be transported in a 500-gallon water <br /> trailer, 55-gallon drum, or a 325-gallon truck-mounted tank, to IT's San Jose or <br /> Sacramento office location for temporary storage. IT will arrange for transport and <br /> disposal of the purged groundwater through Integrated Waste Stream Management, Inc. <br /> Field measurements of pH, specific conductance, and temperature will be recorded in a <br /> waterproof field logbook. Figure B-2 shows an example of the water sample field data <br /> sheet on which field data will be recorded. Field data sheets will be reviewed for <br /> completeness by the sampling coordinator after the sampling event is completed. <br /> The pH, specific conductance, and temperature meter will be calibrated each day before <br /> field activities begin. The calibration will be checked once each day to verify meter <br /> performance. Field meter calibrations will be recorded on the water sample field data <br /> sheet. <br /> Well Sampling <br /> A Teflon bailer is the only equipment acceptable for well sampling. When samples for <br /> volatile organic analysis are collected, the flow of groundwater from the bailer will be <br /> regulated to minimize turbulence and aeration. Glass bottles of at least 40-milliliters <br /> volume and fitted with Teflon-lined septa will be used in sampling for volatile organics. <br /> These bottles will be filled completely to prevent air from remaining in the bottle. A <br /> positive meniscus will be formed when the bottle is completely full. A convex Teflon <br /> septum will be placed over the positive meniscus to eliminate air. After the bottle is <br /> capped, it will be inverted and tapped to verify that it contained no air bubbles. The <br /> sample containers for other parameters will be filled, filtered as required, and capped. <br /> When required, dissolved concentrations of metals will be determined using appropriate <br /> field filtration techniques. The sample will be filtered by emptying the contents of the <br /> Teflon bailer into a pressure transfer vessel. A disposable 0.45-micron acrylic copolymer <br /> filter will be threaded onto the transfer vessel at the discharge point, and the vessel will <br /> Sac\N:ICTmPkhDatalArchive\Arco\5469\Reports15469p1D3.doc-95Usg:1 IT Corporation <br /> B-3 02/28/00 <br />