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I 10 use The baler will be lowered to a point just below the liquid level. Iretrieved, and observed for floating hydrocarbon Vquwd measurements will be recorded to the nearest 0.01 foot in the field I logbook. The ground-water elevation at each monitoring well will be cal- culated by subtracting the measured depth to water from the surveyed elevation of the top of the well casing (Every attempt will be made to mea- sure depth to water for all wells on the same day ) Total well depth vAil then be measured by lowering the sensor to the bottom of the well. Total well depth, used to calculate purge volumes and to determine whether the well screen is partially obstructed by silt, will be recorded to the nearest 0 1 foot in the field logbook. Well Purging I Before the sampling event, a polyvinyl chloride baler, low-flow sub- mersible pump, or Teflon baster will be used to purge standing water in the casing and gravel pack from the monitoring well. Monitoring wells will be purged according to the protocol presented in Figure B-1. In most morn- tonng wells, the amount of water purged before sampling will be greater than or equal to three casing volumes. Some monitoring wells are expected to be evacuated to dryness after removing fewer than three cas- ing volumes These low-yield monitoring wells will be allowed to recharge for up to 24 hours Samples will be obtained as soon as the monitoring wells have recharged to a level sufficient for sample collection If insuffi- cient water has recharged after 24 hours, the monitoring well %nil be recorded as dry for the sampling event Ground water purged from the monitoring wells will be contanenzed :n 55-gallon drums for subsequent disposal. Drums will be stored on site at a Shell-designated location. EMCON will arrange for the disposal of the purged ground water and the removal of drums through Crosby and Overton During storage, drums will be properly labeled with a Shell drum label Field measurements of pH, specific conductance, temperature, turbidity and dissolved oxygen (when requested) will be recorded in a waterproof field logbook. Figure B-2 shows an example of the Water Sample Field Data Sheet on which field data are recorded Feld data sheets will be reviewed for completeness by the sampling coordinator after the sampling �• event is completed. PRA P91 K022 AOw Rev 0 February 7, 1992