ARCHIVED REPORTS_2010_11 - Laserfiche WebLink

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1. The pH, conductivity, and =bidity meters will be calibrated ata °. urn at the beginning of each sampting day using commercially obtained.'simdards. Calibration will be checked two to three times during the day to evaluate the potential that the calibration is driffing tbroughout the day. •If in=ument ddft is detected in the field, the measurements taken during puzZing and sampling will be adjusted accordingly, Example calibration logs are.included 1n.Apliendix'C. During purging and sampling of the wells the lastruments will be used in the same manner as during calibration. 2. Depth to water will be treasured 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): 4-inch well: ET6tal Well Depth from the mark on the well casing (ft) - DTW (g)) x 0.653 gal/fL .3.' Prior to purging, the.water will be•.cxamined-byusing-a d sgosabla-bailer that is clear- enough to see through.. Features such as iramis'ble 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 be purged using the-purge purnps-zDue to the fact that the p nps must k purge water from depths as great as-70 to 80 feet below ground surface,purge rates range from I/4 to I gallon per minute. Thi.s'purge rate does not appear to exceed the recharge rates. of the wells.. . Purge water will be discharged to-'the ground (see Section 4.4.6)- Dtpth to water measurcments will be taken periodically during puraing. The purpose of these measurements is to monitor drawdown. Lf a decrease in gromadwatw elevation is notedthe . rate will be until 'laza(purge:talc equals recharge rate)is achieved. The ftevency of meat will be-once every five .minutes initially decreasing to once every one-Iialffhour once equilzibrivat has been ren died. If equilibrium cannot be reached,it will be atcessaiy to purge the well to dryness. Purge. unffl less than 100% of thcariginal volume of W3tCr.=Mi= in the well, Hand Wiling ma be required to meet this objective. Monitor the DTW every IS minutes to evaluate r=harge. Start sampfe collection when either two feet of water has filled the well or 1.75 bows has elapsed since the and ofpurging. Collectvolatile organics no later than two - ho= aft4r purging. Racord all actions and measurements also ' with purging a well. dry on the Purge ion and Sample Log. 84 11231 OR325 A-7 July 14,2000 dei Enc.