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1. The pH, conductivity, and turbidity meters will be calibrated at a minimum at the beginning of each sampling day using commercially obtaibed.standards. Calibration will be checked two to three times during the day to evaluate the potential that the calibration is ddfdng throughout the day. If instnnnent drift is detected in the field, the mem=ments taken dming purging and sampling will be adjusted accoaiingly. Example calibration logs are included in.Appendi'x'C. During purging and sampling of the wells the instruments will be used in the same manner as dxring calibration. 2. Depth to water will be measured again, prior to sampling, in each well as described in Section 4.4.1 and recorded on the Purge Characterization aad Sample Log. The volume of groundwater in the well using will be calculated using the following equation(s): 4-inch well: (Thiel Well Depth from the mark on the well casing (ft) - DTW (ft)) x 0.653gal/fL .3.' Prior to purging, thc-water•will.be%exaunined••:by-using-a di sable bailer that is clear- -enough to see through. Pcafinrs such as immiscible lay= will be noted and m ;t„ ;Sra-ble layers-are observed the well will not be purged prior to sampling. 4__ The well will then be purged using the-purge pumps_:Due to thc-fact tba:t the pumps must Pe water from depths as great as 70 tci S0 fess below ground surface,Purge rates range from I/4 to 1 gallon per minute. Thi.s'purge rate does not appear to exceed the recharge rates. of the wells. Purge water will be ALwl argcd to-the ground (sec Section 4.4.6)- to water in cats will be taken periodically during purging. The purpose of these measurements is to monitor drawdown. If a decrease in groundwater elevation is .noted, the purge rate will be untoequilibrium(purge rate equals rehazge rate) is achieved. The fre�y of mc&sure:mcnt will be-once every five minutes initially decreasing to once every one-hatfhour once equt'h�has been reached. If equilibrium cannot be reached,it will be to purge the well to dryness. Purge. until less than 101% of the ori " volume of water repi2ins in the well, Hand bairmg y be acquired to meet this objective. Monitor the DTW every 15 minutes to evaluate rtcharge. Start sample collection when either two fat of water has filled the well or.1.75 hours has elapsed since the end of purging. Collect volatile organics no later than two hours after pmziq. Record all actions and measur=c= associated with purging a well dry on the Purge ° � tion and SamPle Log. 1144-Ry IIU3��1OR34225 A-7 July 14,200 /08cKiiG KR.