ARCHIVED REPORTS_2008_22 - Laserfiche WebLink

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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 wi71 be checked two to three tunes during the day to evaluate the potential that the calibration is driffing throughout the day. -If instrument drift is detected in the field, the measurements taken during purging and sampling will be adjusted acconlingly. Example calibration Iogs arc included in.Ap ' dix'C.. During purging and sampling of the welts the instruments 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 easing will be calculatedUs* the following equa$on(s)• 4-inch well.- '(Total Well Depth from the mark on the well casing (ft) - DTW (ft)) x 0_653 gal/fL .3., Prior to purging, the-water,will be-. -br using-a disposable'bailer that is ci mr7 ,enough to see through. Features such as immiscible layers will be noted and-measured. If irnmiscibie layers-arc observed the vrc not be purged prier to sampling_ 4_ The well will then be purged using the e _Due to the-fact that the pumps must purge water from depths as great as-70 to 80 feet below ground surfaces purge rates range fiom 114 to I gallon per minute. This-purge rate docs not appear to exceed the recharge - ratcs of the wells. Purge water will be discharged to-the ground (see Section 4.4.6)- Depth to watt'measurements will be taken paiodically duing pig- The purpose of these moments 3s to mon tar-dr-avdowm If a decrease in groundwater elevation is mooted,the purge rate will be 'tun(purge rate equals rage rate)is achieved. The frequ=cy of measurement will be-once every five minutes initially decreasing to once every on hour once equili-brium has been reached. If equilibrium cannot be reached,it will be necessary to purge the well to dryness. Purge. until less than 104/0 of the (miginal volume of vmtcr repzains in the well. Hand Wing may be requhvd to meet tWsobj6cdve. Monitor the DTW every 15 minutes to evaluate r=harge. Start sample collection whet either o fat of water has filled the well or-135 hours has elapsed since the end of purging. Collectvolatile organics no later than two hours after purging. Record all actions eats associated with purging a well dry on the Forge Characterization and Sample Log. 449-8 1123 OR325 A•7 July 14,2000 CWOkht 2000 Kkk ldcr,lac.