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1 .I i AEGIS ENVIRONMENTAL, INC. STANDARD OPERATING PROCEDURE RE: MEASURING LIQUID LEVELS USING WATER LEVEL OR INTERFACE PROBE SOP-12 Field equipment used for liquid-level gauging ty ically includes the measuring probe (water-level or interface) and product bailer(s). The field kit also includes cleaning supplies (buckets, TSP, spray bottles, and deion zed water) to be used in cleaning the equipment between wells. Prior to measurement, the probe tip is lowered int the well until it touches bottom. Using the previously established top-of-casing or top- f-box (i.e., wellhead vault) point, the probe cord (or halyard) is marked and a measun g tape (graduated in hundredths of a foot) is used to determine the distance between he 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 easure 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) indicator and the DTW measurement is made accordingly. The steady tone indicates floating hydrocarbons. In this case, the probe is slowly raised until the steady tone ceases. This is the depth-to- roduct (DTP) indicator and the DTP measurement is made accordingly. The process of lowering and raising the probe mut be repeated several times to ensure accurate measurements. The DTW and DTP measurements are recorded on the liquid- level data sheet. When floating product is indicated by the probe's response, a product bailer is lowered partially through the product-wa er interface to confirm the product on the water surface, and as further indication of product thickness, particularly in cases where the product layer is quite thin. This measurement is recorded on the data sheet as "product thickness." In order to avoid cross-contamination of wells during the liquid-level measurement process, wells are measured in the order of "clea " to "dirty" (where such information is available). In addition, all measurement equipment is cleaned with TSP or similar solution and thoroughly rinsed with deionized water be ore use, between measurements in respective wells, and at the completion of the day's use. ATTACHMENT/SOP-12lMARCH 1993