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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 obtaiixed.standards. Calibra$®n wd11 be checked two to three times during the day to evaluate the potential that the calibration a is drifting throughout the day. -If Instrument drift is detected in the field, the measurements taken during puTing and sampling will be adjusted accotdjrgjy. Example calibration logs are included in APIndix-C C. During purging and sampling of the wells the instruments will be used in the same manner as&uing calibrarion. 2. Depth to water will be measured again,prior to sazuPlmg, in each wellas described in Section 4.4.1 and recorded on the Purge Characterization and Sample Log. The volume of groundwater in the well casing will be calculated using the following equation(s): 44n6 well: '(Total Well Depth fiTrrfL the mark on the well casing {ft) - DTW (ft)) x 0.653 gal/ft. 3.' Prior to purging, the water will.be.examined by-using a disposable bailer that is clear- ,enough to see through. Features such as immiscible layers will be no and measured. If immiscible layers-arc observed the well will not be purged prior to sampling- 4- The well will then beed using the-purge P '8 g Fig SPS-=Due to the fact than the pumps must Purge water from depths as great as-70 to 80 feet below ground surfac-,purge rata range from 1/4 to I gallon per.minute_ This-purge rate does not appear to exceed the recharge rates, of the wells. - purge water will be discharged to-the grov4d (sec Section 4.4.6). Depth to water measurcinents will be taken periodically during purging. The purpose of -these measurements is to monitor drawdown. if a do erase in groundwater elevation is ztotcd,the purge rate will be d=eas until equilibrium (purge rate equals recharge rate) its achieved. The frequency of measurement will be once every five minutes initially decreasing to once every one-half hour once equilibriu n has been reached- If equilibrium cannot be reached,it will be necessary to purge the well to dryness. Purge. until kis than 10'/® of the original volume of water remains in the well. Hand bailing Pay be required to meet thus objective. Monitor the DTtY every 15 minutes to evaluate ,recharge. Start sample collection when either two feet of wa er has filled the wellor.1.75 hours has elapsed since the end of purging. Collect volatile organics no later than two hours after purging. R.ccord all actions and measurements associated with purging a well dry on the Purge Charact*dzation and Sample Log. 0234U-949-Fo 1\31 OR325 A-7 My 14,2000 2A00 KkU M4C4 tae.