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r:_ ~ r III IIIIIIIIIIIIIIII <br />STATE OF COLORADO <br />DIVISION OF MINERALS AND GEOLOGY <br />Depznmenl of Natural Resources <br />1313 Sherman SL, Room 215 <br />Denver, Colorzdo 80203 <br />Phone: 1303) 866-3567 <br />FAX: (3031 832-8106 <br />DATE: <br />TO: <br />FROM: <br />RE: <br />J1. <br />2. <br />/3 . <br />4. <br />JULY 12, 1996 <br />DAVE BERRY <br />JOE DUDAS$ <br />~~ <br />DPPARTMENT OF <br />NATURAL <br />RESOURCES <br />Roy Ronie. <br />Governor <br />)a mec S. Lnchhead <br />Eaeculive Diieclor <br />ntidiael B. long <br />Division Director <br />ADDITIONAL HYDROLOGY ADEQUACY QIIEBTIONB, BOWIE NO. 2 <br />MINE, PERMIT NO. C-96-083, 80WZE RE80IIRCE8 LIMITED <br />The completion diagrams for the bedrock drill holes DH-54 and <br />DH-55 state that a portion of the casing is slotted while the <br />remaining portion is solid. However, the stippling in the <br />drawing shows that the entire casing is slotted. Please <br />reconcile this difference. <br />On page 2.04-25 of the permit application, it is stated that <br />the lower perched water zone in the Mesaverde is located <br />between the Rollins Sandstone and the "C" coal seam. However, <br />the monitoring well for this lower perched zone, DH-55, <br />appears to be receiving ground water inflow from a zone just <br />above the lower "B' coal seam upward 283 feet, presumably <br />almost into the upper "D" coal seam. This is because ground <br />water can enter the gravel pack along the entire length of the <br />casing and enter the well through the slotted casing. This <br />monitoring well would appear to be sampling a zone which would <br />include the additional lower "D" coal aquifer, while leaving <br />out the zone between the Rollins Sandstone and the lower "B" <br />coal seam. Please explain how the monitoring well DH-55 can <br />monitor the entire lower perched water zone, without including <br />any other zone. <br />Referring to Map 09, Hydrologic Monitoring Location Map, and <br />Map 11, Lower Perched Water Zone Mesa Verde Formation, the <br />location of monitoring well DH-55 indicates that the well is <br />neither upgradient nor downgradient of the lower perched water <br />zone. Without an upgradient well and a downgradient well, any <br />change in aquifer water quality or quantity could not be <br />directly attributed to the effects of mining. How is the <br />monitoring of one well, particularly at this location, capable <br />of monitoring the effects of mining on the aquifer? <br />Referring to Map 09, Hydrologic Monitoring Location Map, it <br />