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Sample Collection <br /> tSample collection procedures include equipment cleaning, water-level and <br /> total well-depth measurements, and well purging and sampling <br />' Equipment Cleaning <br /> Before the sampling event is started, equipment that will be placed in the <br />' well or will come in contact with ground water will be disassembled and <br /> cleaned thoroughly with detergent water, and then steam cleaned with <br /> delonlzed water During field sampling, equipment surfaces that are <br /> placed In the well or contact ground water will be steam cleaned with <br /> delonlzed water before the next well is purged or sampled <br /> ' Water-level Floating Hydrocarbon, and Total Well-depth Measure- <br /> ments <br /> Before purging and sampling occurs, the depth to water, floating hydro- <br /> carbon thickness, and the total well depth will be measured using an <br /> ' oil/water interface measuring system The oil/water interface measuring <br /> system consists of a probe that emits a continuous audible tone when <br /> ' immersed In a nonconductive fluid, such as oil or gasoline, and an inter- <br /> mittent tone when immersed In a conductive fluid, such as water Liquid <br /> levels will be recorded relative to the tone emitted at the ground-water <br /> surface The probe will be decontaminated by rinsing with a nonphosphate <br /> detergent solution and then double rinsing with deconized water or steam <br /> cleaning after each use Alternatively, an electric sounder and a t3ottom- <br /> ' filling, clear Teflon® bailer may be used to record floating hydrocarbon <br /> thickness and depth to water <br /> The electric sounder is a transistorized instrument that uses a reel- <br /> mounted, two-conductor, coaxial cable that connects the control panel to <br /> the2nsor �t,ln markings :re st3Ped :± `.^.^: r!3rpala The 'eater <br /> e ., G�-Yf„ M. <br /> level will be measured by lowering the sensor into the monitoring well A <br /> low-current circuit is completed when tha sensor contacts the water, which <br /> serves as an electrolyte The current is amplified and fed into an indicator <br /> ' light and audible buzzer, signaling when water has been contacted A <br /> sensitivity control compensates for highly saltine or conductive water The <br /> electric sounder will be decontaminated by rinsing with a nonphosphate <br /> ' detergent solution and then double rinsing with delonlzed water after each <br /> ' PRA P91 K022 AOW Rev 0 February 7, 1992 <br />