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For quality control purposes,a duplicate vapor sample should be collected from each sampling port. This sample is then put on hold at the laboratory pending the initial analysis. To minimize the potential for cross-contamination between vapor samples,the polyethylene tubing,if not sample dedicated,is thoroughly cleaned and rinsed. Vapor samples are subject to very limited holding times,typically 48 hours. Thus,care must taken to avoid delays in submittal of vapor samples to the laboratory. In the event the vapor samples cannot be submitted to the analytical laboratory on the same day they are collected,they are to be temporarily stored in the dry,non-refrigerated, packed cooler until the very first opportunity for submittal well within the required holding time,taking into account the time needed for shipment to and receipt by the laboratory. SOP-12 MEASURING LIQUID LEVELS USING WATER LEVEL METER OR INTERFACE PROBE Field equipment used for liquid-level gauging typically includes the measuring instrument(water-level meter or interface probe)and product bailer(s). The field kit also includes cleaning supplies (buckets,solution,spray bottles,and deionized water)to be used in cleaning the equipment between wells. Prior to measurement,the instrument tip is lowered into the well until It touches bottom. Using the previously established top-of-casing or top- of-box(i.e.,wellhead vault)point,the probe cord(or halyard)is marked and a measuring tape(graduated in hundredths of a foot)is used to determine the distance between the probe end and the marking on the cord. This measurement is then recorded on the liquid-level data sheet as the"Measured Total Depth"of the well. When necessary in using the interface probe to measure liquid levels, the probe is first electrically grounded to either the metal stove pipe or another metal object nearby. When no ground is available, reproducible measurements can be obtained by clipping the ground lead to the handle of the interface probe case. The probe tip is then lowered into the well and submerged in the groundwater. An oscillating(beeping)tone indicates the probe is in water. The probe is slowly raised until either the oscillating tone ceases or becomes a steady tone. In either case,this is the depth-to- water(DTW)indication and the DTW measurement is made accordingly. The steady tone indicates floating liquid hydrocarbons (FLH). In this case,the probe is slowly raised until the steady tone ceases. This is the depth-to-product(DTP)indication and the DTP measurement is made accordingly. The process of lowering and raising the probe must be repeated several times to ensure accurate measurements. The DTW and DTP measurements are recorded on the liquid-level data sheet. When FLH are indicated by the probe's response,a product bailer is lowered partially through the FLH-water interface to confirm the FLH on the water surface and as further indication of the FLH thickness, particularly in cases where the FLH layer is quite thin. This measurement is recorded on the data sheet as"FLH thickness" In order to avoid cross-contamination of wells during the liquid-level measurement process,wells are measured in the order of"clean"to "dirty"(where such information is available). In addition,all measurement equipment is cleaned with solution and thoroughly rinsed with deionized water before use,between measurements in respective wells,and at the completion of the days use.