2003-09-23_REVISION - M1999034 - Laserfiche WebLink

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COLORADO DEPARTMENT OF PUBLIC Is,EALTH AND ENVIRONMENT WATER QUALITY CONTROL DIVISION WATER QUALITY PROTECTION SECTION ROUND-WATER PEP,MIT GUIDPNCE SUGGESTED MOMTORING WELL SAMPLING PROTOCOL B. CrROUTIB WATER SAMPLE CQLLECTFON 2. METHOD A FOR SAMPLE COLLECTION This method is to be utilized for those wells that produce a sufficient volume of water and have a rapid recovery rate. a. Prior to purging/sampling, calibrate all test equipment used in the field according to manufactrue's specifications. Enter all equipment catioration data into a field logbook. Clean all field test equipment and ground-water sampling equipment. b. Purge the well water into a collection container to be able to measure and record temperature, pH, ~ o~}*gcn]- Contame purgitt~ ttnrit~e stagiianf w~ m tfie castng~tas-been replaced by formation water. This is best determined by logging the reaaings for temperature, pH, conductivity [and dissolved oxygen, where applicable) readings. After approximately three czsing volumes have been removed from the well and once G-re most receat r°.zding is within 10% of the previous two readings for each individual field parameter, aground-water sample will be taken. If the field pazameter do not stabilize, a minimum of five casing voltunes shall be removed from the well prior to taking aground-ware: sample. c. If a bailer is used to purge the well and to take the ground-water sample, the bailer is to be lowered into the well to what hereinafter is referred to •as the "sample depth". "Sample depth" is determined by lowering the bailer to the bottom of the well. Once the bailer is gently resting on the bottom, the field person is to mark this location on the cable. The mazk is to be placed directly across from the measuring point while the cable is held taut. Raise the bailer one-foot above the bottom of the well. Mazk the cable or place adhesive tape on the cable to indicate the sample depth for future reference. Taking a sample at this elevation should avoid undue amounts of sedimentr ir, the sample and prevent sediment interfering with closure of the bailer valve. The well should be purged by bailingsom the bottom of the well, until the water level is drawn down to the lowest possible level. Take a "throw-away" sample to deterrnine temperature, pH and conductivity. Record the values and the volume bailed Allow the water level to rechazge to at least four feet in the bottom of the well, or to whatever depth the water recovers in well -{less-tkan faun feet} -fake-another"throw-away" sazn n ' ue is proce ure un~approzlmateIy three volumes have been removed and the pazameter aze within 10% of the previous two readings for each parameter. At this time, the field person will take a sample. If the field parameter do not stabilize, a minimum of five casing volumes shall be removed from the well prior to taking aground-water sample. d Prevent sampling equipment from coming into contact with the ground or a potentially contaminated surface.