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AEGIS ENVIRONMENTAL, INC. <br /> &STANDARD OPERATING PROCEDURE <br /> RE: MEASURING LIQUID LEVELS USING WATER LEVEL OR INTERFACE PROBE <br /> SOP-12 <br /> Field equipment used for liquid-level gauging typically includes the measuring probe (water-level or <br /> interface) and product bailer(s) The field kit also includes cleaning supplies (buckets, TSP, spray <br /> bottles, and deionized water) to be used in cleaning the equipment between wells <br /> Prior to measurement, the probe tip is lowered into the well until it touches bottom Using the <br /> previously established top-of-casing or top-of-box (i e , wellhead vault) point,the probe cord(or halyard) <br /> is marked and a measuring tape (graduated in hundredths of a foot) is used to determine the distance <br /> between the probe end and the marking on the cord This measurement is then recorded on the liquid- <br /> level data sheet as the "Measured Total Depth" of the well <br /> When necessary in 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 is available, <br /> reproducible measurements can be obtained by clipping the ground lead to the handle of the interface <br /> probe case <br /> The probe tip is then lowered into the well and submerged in the groundwater An oscillating (beeping) <br /> tone indicates the probe is in water The probe is slowly raised until either the oscillating tone ceases <br /> or becomes a steady tone In either case, this is the depth-to-water (DTW) indicator and the DTW <br /> Weasurement is made accordingly The steady tone indicates floating hydrocarbons In this case, the <br /> probe is slowly raised until the steady tone ceases This is the depth-to-product (DTP) indicator and <br /> the DTP measurement is made accordingly <br /> The process of lowering and raising the probe must be repeated several times to ensure accurate <br /> measurements The DTW and DTP measurements are recorded on the liquid-level data sheet When <br /> floating product is indicated by the probe's response, a product bailer is lowered partially through the <br /> product-water interface to confirm the product on the water surface, and as further indication of product <br /> thickness, particularly in cases where the product layer is quite thin This measurement is recorded <br /> on the data sheet as "product thickness " <br /> In order to avoid cross-contamination of wells during the liquid-level measurement process, wells are <br /> measured in the order of "clean" to "dirty" (where such information is available) In addition, all <br /> measurement equipment is cleaned with TSP or similar solution and thoroughly rinsed with deionized <br /> water before use, between measurements in respective wells, and at the completion of the day's use <br /> i <br /> ATTACHMENTJSOP 12fMARCH 1993 <br />