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' CO i.ORA DO GJES TMOREf,AND, INC. Orchard Valley Mine - Perrnit Application Colorado MLRD/OSM Joint Review Rydrology, Groundwater Because of the confusion surrounrliny the possible existence of groundwater in the permit and adjacent areas, further study is needed. Much of the information for thrr yrounr7i,•ater study can probahly be generated using in-house information and brl a site inspection by CWI staf;~ of theiz~ groundwater consultant. Colorado Westmoreland, Inc., needs to provide the following information: Drill Logs of exploratory and core hales in the permit and adjacent areas. Ber'a use the logs arc• geophysica.t logs, it would assist the analysis if the Logs were interpreted by CIJI and the type, location, and thickness of the strata were noted on the logs. Several East-West and North-South cross-sections through the permit and adjacent areas showing the geology down to and including the first aquifer and other coal seams below the lowest coal scam to be mined. The location of the cross-sections should be shown on a plan view of the permit area. The drill logs used to draw a cross-section should be plotted on the cross-section. These cross-sections can be used to locate fault zones and associated fracture zones and con tinuou.s sandstone beds or other strata which could act as aquifers. If the cross-sections indicate that there are strata or zones which can be aquifers, the existence of water can perhaps be determined from in-house sources. These in-house sources include: Information developed during drilling, abandoned mine workings adjacent to the permit area, the existence of springs, seeps, of wells in the area, especially if these are found downdip (north) of the mine plan area; the results of testing Pad No. 47 as a water source; the existence of heavier vegetation along the outcrop of various strata, again, especially if they outcrolr downdip of the mine plan area; and, past experience during mining. If fault and fracture zones encountered during past mining are known to be extensive, both vr.rticalhJ and horizontally, and it can be shown that they intersect the strata which are potential aquifers, then the rate, duration, and quantitiy of groundwater flow or lack thereof, from these zones can provide information concerning the existence of groundwater. The springs and seeps can also indicate the existence of other alluvial aquifers similar to the one CWI i.s currently using as a water source. The 92 springs and stockpondsabove t)ic mine area, mentioned in the application, need to be clearly located on a map or maps, preferably of 1 inch = 500 feet scale. The map should clearly differentiate between springs and ponds. The location, extent, and piezometric surface subsurface waters within and adjacent to the permit area must be mapped and described; such groundwater systems must be delineated using in-house infrirmationrby field studies, or by drilling exploratory wells, if necessary. '4. ~ ,iA I i.