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Groundwater Sample Collection <br /> = After wells are purged, or not purged, according to TSR instructions, samples are collected for laboratory <br /> analysis. For wells that have been purged using conventional pump or bail methods, sampling is <br /> conducted after the well has recovered to 80 percent of its original volume or after two hours if the well <br /> does not recover to at least 80 percent. If there is insufficient recharge of water in the well after two <br /> hours,the well is not sampled. <br /> Samples are collected by lowering a new, disposable, '/z-inch to 4-inch polyethylene bottom-fill bailer to <br /> just below the water level in the well. The bailer is retrieved and the water sample is carefully transferred <br /> to containers specified for the laboratory analytical methods indicated by the TSR. Particular care is <br /> given to containers for volatile organic analysis (VOAs) which require filling to zero headspace and <br /> fitting with Teflon-scaled caps. <br /> After filling, all containers are labeled with project number (or site number), well designation, sample <br /> date, sample time, and the sampler's initials, and placed in an insulated chest with ice. Samples remain <br /> chilled prior to and during transport to a state-certified laboratory for analysis. Sample container <br /> descriptions and requested analyses are entered onto a chain-of-custody form in order to provide <br /> instructions to the Iaboratory. The chain-of-custody form accompanies the samples during transportation <br /> to provide a continuous record of possession from the field to the laboratory. If a freight or overnight <br /> carrier transports the samples,the carrier is noted on the form. <br /> For wells that have been purged using low-flow methods, sample containers are filled from the effluent <br /> stream of the bladder or peristaltic pump. In some cases, if so specified by the TSR, samples are taken <br /> from the sample ports of actively pumping remediation wells. <br /> Sequence of Gauging,Purging and Sampling <br /> The sequence in which monitoring activities are conducted are specified on the TSR. In general, wells <br /> are gauged beginning with the least affected well and ending with the well that has the highest <br /> concentration based on previous analytic results. After all gauging for the site is completed, wells are <br /> purged and/or sampled from the least-affected to the most-affected well. <br /> Decontamination <br /> In order to reduce the possibility of cross contamination between wells, strict isolation and <br /> decontamination procedures are observed. Portable pumps are not used in wells with LPH. Technicians <br /> wear nitrile gloves during all gauging, purging and sampling activities. Gloves are changed between <br /> wells and more often if warranted. Any equipment that could come in contact with fluids are either <br /> dedicated to a particular wells, decontaminated prior to each use, or discarded after a single use. <br /> Decontamination consists of washing in a solution of Liqui-nox and water and rinsing twice. The final <br /> rinse is in deionized water. <br /> Exceptions <br /> Additional tasks or non-standard procedures, if any,that may be requested or required for a particular site, <br /> and noted on the site TSR, are documented in field notes on the following pages. <br /> 115/04 version <br />