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Where TOC = top-of-casing elevation, DTW =depth to water(interface), and PT = PSH <br /> thickness <br /> If PSH thickness is less than 0 02 foot, and the well is planned for purging prior to sample <br /> collection, the well is purged and sampled in accordance with the sample collection section of <br /> this SOP If the PSH thickness is 0 02 foot or greater, the PSH is bailed from the well, and left <br /> onsite in a labeled and sealed container No sample is collected for analysis from wells having a <br /> PSH thickness of greater than 0 02 foot <br /> 4. No-Purpae Sampling <br /> Well purging is not conducted prior to sampling if purging is not needed to meet technical and/or <br /> regulatory project requirements Following collection of water level measurements, wells that are <br /> not purged are sampled according to the protocol in the sample collection section of this SOP <br /> 5. Purging Procedures <br /> Well purging is conducted prior to sampling if purging is needed to meet technical and/or <br /> regulatory project requirements If purging is conducted, the monitoring wells are purged using a <br /> vacuum truck, submersible electric pump, bailer, hand pump, or bladder pump, as appropriate for <br /> site conditions A surge block may be used if it becomes apparent during purging that the well <br /> . screen has become bridged with sediment or the produced groundwater is overly turbid <br /> During the purging process, groundwater is monitored for temperature, pH, conductivity, <br /> turbidity, odor, and color These parameters are recorded on a water sample log Purging <br /> continues until all stagnant, water within the wells is replaced by fresh formation water, as <br /> indicated by removal of a minimum number I of well volumes and/or stabilization of the <br /> above-outlined parameters Sampling is performed after the well recharges to at least 80 percent <br /> of hydrostatic <br /> Purge water is stored on site in Department of Transportation-approved, 55-gallon drums until <br /> water sample analytical results are received from the laboratory If active groundwater treatment <br /> is occurring at the site, purge water may be disposed of through the treatment system, or the <br /> purge water may be transported off site as non-hazardous waste to an approved off-site disposal <br /> facility If permanent pumps are installed in the wells for groundwater remediation, purging may <br /> be accomplished by operating the pumps for at least 24 hours before sampling to ensure adequate <br /> purging <br /> i <br /> Matn',D\EnvuonmentaMarmarTexaco\Workplan'\042003 wpd 2 <br />