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GROUNDWATER ELEVATION Y <br /> Before the sampling event is begun, monitoring wells at the site will be measured for <br /> static water levels during a single water level survey. Water levels will be converted to <br /> elevations in mean sea level and displayed on a groundwater contour map. All (or <br /> selected) monitoring wells will be sampled for chemical constituents after the water-level <br /> survey is completed. <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 increments. <br /> The water level will be measured by lowering the sensor into the monitoring well. A <br /> low-current circuit is completed when the sensor contacts the water, which serves as an <br /> electrolyte. The current is amplified and fed into an indicator light and audible buzzer, <br /> signaling when water has been contacted. A sensitivity control will compensate for highly <br /> saline or conductive water. The electric sounder will be decontaminated by rinsing with <br /> 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 <br /> by 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 0.5 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, and spring (or surface water) sampling. <br /> Equipment Cleaning <br /> Containers used for sample collection are batch-certified clean directly from the supplier. <br /> Sample containers are used only once and discarded after analysis is complete. <br /> During field sampling, equipment surfaces that are placed in the well or contact <br /> groundwater will be steam cleaned with deionized water before the next well is purged <br /> or sampled. <br /> SAC/pjU093M9390011.8a1-94/lfc:9 Rev.0, 10/17/94 <br /> 0939-001.18 A-2 <br />