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IF-AA RFCEIVED AUG 15 1991 ENV1 0fNJfV[ttMTAL HEALTH STANDARD OPERATING PROCEDURES PE R M'T;3[RV 3(`FS RE:GAUGING LIQUID LEVM USING WATER LEVEL PROBE OR INTERFACE PROB SOPS The complete list of field equipment for liquid level gauging is assembled in the Technical office prior to departure to the field This includes the probe(s), light filter(s), and product bailer(s) to be used for liquid levels (tested in test well before departure) The field kit also mcludes cleaning supplies(buckets,TSP,spray bottles,and deionized water)to clean the equipment between gauging wells When using the water level probe to gauge liquid levels,the probe tip is lowered into the well until the unit sounds The top-of-casmg (TOC) point is determined This point is marked with a dot or a groove, or is an obvious high point on the casing, or is the north end of the casing The place on the probe-cord that corresponds with this TOC point is marked and an engineer's tape is used to measure the distance between the probe end and marking on the cord This measurement is then recorded on the liquid level data sheet as depth to water (DTW) When using the interface probe to gauge liquid Ievels, the probe is first grounded by clamping it to the metal stove pipe or another metal object nearby When no ground is available, reproduceable measurements can be obtained by clipping the ground lead to the handle of the interface probe case After grounding the probe, the top of the well casing is fitted with a WGR light filter to insure that sunlight does not mterfere with the operation of the probe's optical mechanisms The probe tip is then lowered into the well and submerged in the groundwater An oscillating (beeping) tone indicates that the probe is in water The probe is slowly raised until either the oscillating tone ceases or becomes a solid tone In either case, this is the depth-to- groundwater (DTW) measurement The solid tone indicates that liquid hydrocarbon is present on top of the groundwater To determine the thickness of the liquid hydrocarbon, the probe is slowly raised until the solid tone ceases This is the depth-to-hgwd hydrocarbon (DTLH) measurement The process of lowering and raising the probe must be repeated several times to insure accurate measurements DTW and DTLH measurements are recorded in hundredths of feet on the liquid level data sheet When liquid hydrocarbon is found in a well, a product bailer must be lowered partially through the water/liquid hydrocarbon interface to confirm the thickness of liquid hydrocarbon on the water surface This measurement is recorded on the data sheet as hgwd hydrocarbon tluckness (PT) In order to avoid cross contamination of wells during the hquid level gauging process, wells are gauged in a clean to dirty order (where this information is available) In addition, any gauging equipment is cleaned with TSP and water and thoroughly rinsed with deionizcd water before daily use,before gauging another well on a site, and at the completion of daily use