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Dan Mathews -4- January 18, 1982 <br />5) Provide to the Division a hgdroloqu map on a legible contour mao. This <br />hydrologic map should contain the locations of streams, springs, wells, irrigation <br />ditches (i.e. main ditches, feeder ditches, and return flow ditches), head gates, <br />ponds, lakes, impoundments, monitoring wells, surface monitoring sites, and <br />complete watershed boundaries. <br />6) Conduct a mine inflow study. This inflow study is needed to assess the present <br />impacts of mining on groundwater. This inflow study should include: A) A map of <br />all mine inflows on an updated mine workings map; B) A table keyed to this map <br />with the source of inflows (i.e. faults, fractures, cleating, weeping roofs, <br />floors or walls, etc.), estimates or measurements of flow rates, and mine inflow <br />quality (i.e. pH, temperature, and electro-conductivity); C) A record of the amount <br />of water imported into the mine: D) The amount of water discharged and/or consumed <br />within the mine; and E) A narrative describing the occurance and handling of <br />water within the mine. <br />7) Cliaracterizeirrigation on, and within, the "Glacial-Alluvial Aquifer". The <br />subirrigation character of pasture and orchard lands located on the "Glacial- <br />Alluvial" deposits has not been adequately addressed by the applicant. Test <br />"- <br />' boring, test pits and continuous monitoring of water levels are needed to <br />characterize subirrigation within the "Glacial-Alluvial" deposits. <br />After collecting all of this site-specific data, the applicant should have the data <br />analyzed and should rewrite the hydrologic, alternative water supply systems <br />(water rights), and Alluvial Valley Floor sections of the permit application. <br />The following analyses should be prepared: <br />A. An evaluation of groundwater depletion in the coal seams and the "Glacial- <br />Alluvial Aquifer" induced by underground mining operations. <br />B. An evaluation of the effects of mining on stream flow depletion. <br />C. An evaluation of the effects of mining on subirrigation, surface irrigation <br />systems, irrigation return flows to Ward Creek, and productivity of irrigated <br />pasture and orchard Zands. <br />D. An evaluation of water rights held by Grand Mesa Coal Company, and the need <br />for augmentation of water supplies of other water right holders above and below <br />the permit area. An evaluation, should be made to determine if there is sufficient <br />water available in the Colby Domestic Water System to cover the loss of water to <br />well owners. <br />E. An evaluation of the effects of mining on ground and surface water quality <br />during and after mining. <br />During site inspections, Jim Herron has noted that monitoring wells at the mine <br />site are improperly installed. Perforated casings extend above ground allowing <br />surface waters to enter the well and bias both water levels and groundwater <br />quality. This situation can be remedied by digging down around the casing to a <br />depth of three feet, cutting off the perforated casing, gluing on a section of <br />solid casing, and filling the hole around the well to the surface with cement. <br />These monitoring wells should be fixed immediately to ensure that the data being <br />collected is valid. <br />Grand Mesa Coal Company should provide to the Division completion diagrams for <br />each monitoring well. This diagram should include the perforated or slotted, <br />casing interval, the solid casing interval, the location and type of formation packer <br />or seal, gravel packed interval, open hole interval, backfilled interval, and the <br />geologic units into which the well is completed. <br />