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- <br /> F <br /> ,mss <br /> AEGIS ENVIRONMENTAL, INC. <br /> STANDARD OPERATING PROCEDURE <br /> RE: MEASURING LIQUID LEVELS USING WATER-LEVELOR INTERFACE PROBE <br /> SOP-42 <br /> Field equipment used for liquid-level gauging typically includes the measuring probe <br /> (water-level or interface), light filter(s), and product bailer(s). The field kit also includes <br /> cleaning supplies (buckets, TSP, spray bottles, and deioNzed water) to be used in <br /> 1 cleaning the equipment between wells. <br /> Prior to measurement,the probe tip is lowered into the well until it touches bottom. Using <br /> the previously established top-of-casting (TOC) point, the probe cord (or halyard) is <br /> marked and an measuring tape (graduated in hundredths of a foot) is used to determine <br /> the distance between the probe end and the marking on the cord. This measurement is <br /> then recorded on the liquid-level data sheet as the depth to water (DTW). <br /> When using the interface probe to measure liquid levels, the probe is first electrically <br /> grounded to either the metal stove pipe or another metal object nearby. When no ground <br /> is available, reproducible measurements can be obtained by clipping the ground lead to <br /> the ",andle of the interface probe case. After grounding the probe, the tap of the well <br /> casing is fitted with a light filter to insure that sunlight does not interfere with the operation <br /> of the probe's optical mechanisms. The probe tip is then lowered into the well and <br /> submerged in the groundwater. An oscillating (beeping) tone indicates that the probe is <br /> in water. The probe is slowly raised until either the oscillating tone ceases or becomes <br /> a steady tone. In either case, this is the depth-to-wa#er indicator and the D'1N <br /> measurement is made accordingly. The steady tone indicates floating hydrocarbons. In <br /> this case, the probe is slowly raised unti! the steady tone ceases. This is the depth-to- <br /> product (DTP) indicator and the DTP measurement is made accordingly. <br /> The process of lowering and raising the probe must be repeated several times to ensure <br /> accurate measurements. The DTW and DT? measurements are recorded on the liquid <br /> level data sheet. When floating product is indicated by the probe's response, a product <br /> bailer is lowered partiaLy through the product-water interface to confirm the product on <br /> the water surface, and as further indication of product thickness, particularly in cases <br /> where the product layer is quite thin. This measurement is recorded on the data sheet <br /> as product thickness (PT). <br /> In order to avoid cross contamination of wells during the liquid-level measurement <br /> process, wells are measured in the order of "clean" to "dirty" (where such information is , <br /> available). In addition, all measurement equipment is cleaned with TSP solution and <br />