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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 obtained.'siandards. Calibratio will be checked two to du=times during the day to evaluate the potential that the c:ahi ration is drifting throughout the day. -If instrument ddft is detected im the field, the measurements taken during purging and sampling will be adjusted accordingly. Example calibration Iogs are included in AP�endjx,C•. During Pig and sampling of the wells the instr=ents will be used in the same manner as during 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 and Sample Log. The volume of groundwater in the well casing will be calculated using the following equation(s): 44inch well: '(Total Well Depth from the mark on the well casing (ft)'- DTW (ft)) x 0.653 gall& 3.' Prior to purging, the-water,will-be-.examined-by-using m disposable:butler that is clear~ -enough to sec through_ Feaf ur-s such as immiscible layers will be noted and measured_ ^If immiscible layers-are observed the well will not be purged prior to sampling- 4- The well will then beed e e =Due to the-fact that the pumps muni 1 Pig using thPmSpumps-- Purge urates from depths as great as-70 to 80 ferx below ground surface,purge rates ramie from 1/4 to I gallon per minute- This-purge rate does not appear to exceed the recharge rates. of the wtUs- Purge water will be discharged to-the ground (sce Section 4.4.6)_ Depth to water measm=ents will be taken periodically during purging. The pose of these measurements is to monitor drawdown. If a decrease in groundwater elevation is .nater,, the purge rate will be:decreased until.equill-hrium(purge rate equals nxhargc rate) is achieved. The ficqucacy of measurement will be-once every five minutes initially damming to once every one-half hour once equilibrium has been reached. If equilibrium cannot be reached,it will be necessary to purge the well to dryness_ Purge- until loss than 10%of the original volume of avatar remains in the well, Hand bailing may be required to melt this objective. Monitor the DTW every IS minutes to evaluate recharge. Start sample collation when either two fact of water has filled the well or 1.75 hours has elapsed since the cad of purging. Collect Volatile organics no later than two - hours after purging. Record all actions and measurements associated with purgin8 a well dry on the Purge Characterization and Sample Log. • 21-483-949-S Ik23 I OR325 A-1 July 14,2000 Capyr4*=0 lCidaftkre tae.