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I. The pH, conductivity, and turbidity meters will be 'brated at a minimum at the WM beginning of sampling day using co esraaliy o� ed.` ' . Cali"bratiou be checked two to three times &uiug the day to evaluate the potential that the calibration is dff&g thmughout the day. If instrument drift is detected ffi the field, th, tneasureme=iaken during purging and sampling id° Y• Example calibration logs arc included in Ap ' dix-C. During purging and sampling of the wells the instruments will be used in the same manner as during caftration. 2. Depth to water will be fnegswcd again, prior to s2mPlIng. in each wellas-deiscri-bed in Section 4.4.1 and recorded on the Purge Characterization,and Sample Log. The voIurme of groundwater in the well caking will be calculated using the followingequation(s): 4-inch well: '{Total Well Depth front the mark on the well casing (ft)'_ DTW (ft)) x 0.653 gaUfL .3-, Prior to purghtg, the water be-_=ami ed by-using�a disposable'bailer that is clear- --enough to sec through Features such as immiscible layers will be noted and m 'If immiscible layers-are observed the well will not be purged prior to samplin& 4_ The well will then be purged using the-purge -Duo to the-fact that the punum must purge water from dcpdLs as great as 70 td 80 feel below ground surfface,purge rates range from 114 to I gallon per minute. Thiss-purge rate docs not appear to exceed the recharge of the a water will be discharged to--the ground (see Section 4.4.6)- Depth to waw measw=cnts will be taken periodically during purguig. The purposcof these measurements is to madtor-dravidown. ff a decreas4 in grouadwater,elevation is the purge rate will be i rn(purge rate equals recharge rate) is achieved. The EeVency of m ent will be every five minutes initially decreasing to once every one-halfhour once equihibdum has been rtached- If t be reached,it will be necessary to purge the well to dryness. Purge. until I= than 104/0 of the original 'volume of water in the we11, Hand bailing may be required to meet d&objective, Monitor the DTW every 15 minutes to evaluate recharge. Start sample collection vwhen citha two feet of water has filled the well or-1.75 bourn has elapsed since dw end of purging. Collect volatile organics no law than two - hoeus after purging. Riecord all actions and measur=ents associated with p a Well.odry n the Purge Characterization and Sample Log. !t4 It2310R32S A-7 fitly 14,200