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i <br /> AEGIS ENVIRONMENTAL, INC. <br /> STANDARD OPERATING PROCEDURE <br /> I RE: MEASURING LIQUID LEVELS USING WATER LEVEL OR INTERFACE PROBE <br /> SOP-12 <br /> IField equipment used for liquid level gauging typically includes the measuring probe <br /> (water level or interface), light filter(s), and product bailer(s) The Meld kit also includes <br /> I cleaning supplies (buckets, TSP, spray bottles, and deion:zed water) to be used in <br /> 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 point, the probe cord (or halyard) is marked and <br /> an measuring tape (graduated in hundredths of a foot) is used to determine the distance <br /> Ibetween the probe end and the marking on the cord This measurement is then recorded <br /> on the liquid level data sheet as the depth to water (DTW) <br /> IWhen 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 handle of the interface probe case After grounding the probe, the top 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 ether case, this is the depth-to-water indicator and the DTW <br /> I measurement is made accordingly The steady tone indicates floating hydrocarbons In <br /> this case, the probe is slowly raised until 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 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 /> I 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 /> IIn 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 /> Iavailable) In addition, all measurement equipment is cleaned with TSP solution and <br /> thoroughly rinsed with deiornzed water before use, between measurements in respective <br /> wells and at the completion of the day's use <br /> ATTACHMENT/SOP-12/FEBRUARY 1992 <br /> f <br />