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1 <br />Water levels will be measured with an electric sounder. The electric sounder is a <br />transistorized instrument that uses a reel -mounted, two -conductor, coaxial cable that <br />connects the control panel to the sensor. Cable markings are stamped at 1 -foot <br />increments. The water level will be measured by lowering the sensor into the monitoring <br />well. A low -current circuit is completed when the sensor contacts the water, which serves <br />as an electrolyte. The current is amplified and fed into an indicator light and audible <br />buzzer, signaling when water has been contacted. A sensitivity control will compensate for <br />highly saline or conductive water. The electric sounder will be decontaminated by rinsing <br />with deionized water after each use. <br />Depth to water will be recorded to the nearest 0.01 foot in the field logbook. The <br />groundwater elevation at each monitoring well will be calculated by subtracting the <br />measured depth to water from the surveyed elevation of the top of the well casing. The <br />total depth of the well is then measured in the monitoring wells scheduled for sampling by <br />lowering the sensor to the bottom of the well. The total depth of the well, used to <br />calculate purge volumes and to determine whether the well screen is partially obstructed <br />by silt, will be recorded to the nearest 0.1 foot in the field logbook. <br />SAMPLE COLLECTION' <br />Sample collection procedures include equipment cleaning, water level and total well -depth <br />measurements, well purging and sampling, spring (or surface water) sampling, leachate <br />sampling, and lysimeter sampling. <br />Before the sampling event is started, equipment that will be placed in the well or come in <br />contact with groundwater will be disassembled and cleaned thoroughly with detergent <br />water, and then steam cleaned with deionized water. Any parts that may absorb <br />contaminants, such as plastic pump valves, bladders, etc., will be cleaned as described <br />above, or replaced. <br />During field sampling, equipment surfaces that are placed in the well or contact <br />groundwater will be steam cleaned or rinsed with deionized water before the next well is <br />purged or sampled. <br />11 SA0N .\PJO\093M390031.9BG-94 sdg:4 D-2 Rev. 0, 4/20/95 <br />