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.: <br /> f -- <br />II <br />III IIIIIIII <br />999 IIIII I <br />YVCC <br />Yampa Valley Coal Corporation 129588 Routt County Road #27. Oak Creek, CO 80407 • (303) 879-3800 <br />April 5, 1988 <br />Randy Price <br />Colorado Mined Land Reclamation Division <br />1313 Sherman Street, Room 423 <br />Denver, CO 80203-2273 <br />Dear Mr. Price: <br />'T " `i L <br />I1~~~ ~, f u~t _ <br />~~ ~1 <br />'.I ~\ ( IJ l1i <br /> <br />RE: Twentymile Coal Company; Jetting VS. Bailing Wel]s <br />The MLRD requested Twentymile Coal Company (TCC) to sample some bedrock <br />wells in order to evaluate differences between samples collected by before <br />and after the well was evacuated (jetted) using compressed nitrogen. In <br />addition, I have included data collected from a number of wells sampled in <br />late 1985 and early 1986 according to the procedure recommended above. <br />In November and December, 1987 <br />wells. The water quality data is <br />were collected from each well. The <br />bailer into the well using the w. <br />second sample was collected in the <br />with compressed nitrogen before the <br />volume of water was evacuated before <br />sets of samples were collected from four <br />presented in Attachment A. Two samples <br />first sample was collected by lowering a <br />.ter recovered on the first bail. The <br />ame way, except that the well was jetted <br />well was bailed. At least one casing <br />the sample was collected. <br />The data indicates that for three wells: 006-87-1, 006-82-48, and <br />006-82-48A, the sampling method made no difference. The values for the <br />major ions were not significantly different. For well 006-83-48C the major <br />ions showed a significant difference. The water change from a <br />sodium-carbonate type before jetting to a sodium-bicarbonate type after <br />jetting. The data also indicates that the post-jetting water quality is <br />more like the water quality from the other wells, and therefore is the more <br />representative sample. However, this has to be evaluated for each well as <br />some wells may require evacuation of one bore volume of water prior to <br />sampling. <br />In December, 1985 and January, 1986 series of samples were collected <br />from five monitoring wells. The wells sampled were 001-5-5, 001-5-6, <br />009-5-10, 008-SP-5A and 026-SP-2. A sample was collected from each well and <br />then the well was evacuated with the bailer. A second sample was then <br />collected from each well. <br />