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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 /> Meld equipment used for liquid-level gauging typically includes the measuring probe <br /> (water-level or interface) and product bailer(s) The field kit also includes cleaning <br /> supplies (buckets, TSP, spray bottles, and deionized water) to be used in cleaning the <br /> 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-casing or top-of-box(i e , wellhead vault) point, the probe <br /> cord (or halyard) is marked and a measuring tape (graduated in hundredths of a foot) is <br /> used to determine the distance between the probe end and the marking on the cord This <br /> measurement is then recorded on the liquid-level data sheet as the "Measured Total <br /> Depth" of the well <br /> When necessary in using the interface probe to measure liquid levels, the probe is first <br /> electrically grounded to either the metal stovepipe or another metal object nearby When <br /> no ground is available, reproducible measurements can be obtained by clipping the <br /> ground lead to the handle of the interface probe case <br /> The probe tip is then lowered into the well and submerged in the groundwater An <br /> oscillating (beeping) tone indicates the probe is in water The probe is slowly raised until <br /> either the oscillating tone ceases or becomes a steady tone In either case, this is the <br /> depth-to-water (DTW) indicator and the DTW measurement is made accordingly The <br /> steady tone indicates floating hydrocarbons In this case, the probe is slowly raised until <br /> the steady tone ceases This is the depth-to-product (DTP) indicator and the DTP <br /> 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 DTP 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 partially 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 " <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 or similar solution <br /> and thoroughly rinsed with deionized water before use, between measurements in <br /> respective wells, and at the completion of the day's use <br /> ATTACHM£NTISOP 121MARCH 1993 <br />