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levels were recorded to the nearest 0.01 foot in the field logbook. <br /> Total depth is measured by lowering the sensor to the bottom of the <br /> well . Well total depth was recorded to the nearest 0.5 foot in the <br /> field logbook to facilitate purge volume calculations. The electric <br /> sounder was decontaminated with deionized water after each use. <br /> r <br /> Well Purging and Sampling <br /> s <br /> Prior to initiating the well purging, Well WizardTM Model HR-4500 <br /> pneumatic displacement pumps and P-1201 bladder pumps were permanently <br /> .installed in Monitoring Wells MW-1, MW-2, MW-3, and MW-4. The pump <br /> intakes of the pneumatic displacement pumps were set 6 feet from the <br /> bottom of each of the wells. The intakes of the bladder pumps were <br /> set 1 foot from the bottom of each of the wells. In these wells, the <br /> pneumatic displacement pump was activated for well purging and the <br /> bladder two-stage pump activated for sample collection in order to <br /> eliminate air-water contact. <br /> Immediately prior to sampling Wells -1, -2, -3, and W-4, <br /> standing water in the casing and sand pack was purged from the wells <br /> using the dedicated pneumatic displacement pumps. In these wells, the <br /> amount of water purged prior to sampling was greater than four casing <br /> volumes. During the purging operation, purge water was monitored for <br /> temperature, pH, and electrical conductivity, at an approximate <br /> frequency of one measurement per casing volume removed. Prior to col- <br /> lecting samples for laboratory analysis, these parameters were stabi- <br /> lized to verify that stagnant water had been evacuated from the well ; <br /> that is, two consecutive sets of similar field measurements were <br /> obtained. Purged water was stabilized when (1) the pH was within <br /> ±0.1 pH units, (2) electrical conductivity was within ±5 percent, or <br /> (3) temperature was within ±1.0°F. All records of the above data were <br /> recorded on a field data sheet. Plate C-1 shows an example of the <br /> Water Sample Field Data Sheet. Copies of the field data sheets were <br /> reviewed by the Sampling Supervisor upon the completion of the sam- <br /> pling event. The pH, electrical conductivity, and temperature meter <br /> PJ9 9390102.00D C-3 <br /> 1 <br />