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prior to the submission of a Phase III bond release request. However, the monitoring plan <br />was subsequently modified through MR -12 and the operator committed to reinitiating <br />surface and groundwater monitoring for one year prior to Phase III bond release. <br />4. Probable Hydrologic Consequences <br />April 3, 2012 <br />RN4 <br />a. Ground Water <br />The permit area for the Hamilton Mine consists of 757 acres and is located <br />approximately 2 miles southeast of the town of Naturita in Montrose County. The <br />permit area overlies part of the Nucla - Naturita Coal Field. The area is characterized <br />topographically by dissected mesas sloping to the north toward the San Miguel River. <br />The region is underlain by sedimentary rocks of Jurassic and Cretaceous age which dip <br />gently to the north. The entire permit area is underlain by the Lower Cretaceous <br />Dakota Sandstone, which consists of interbedded conglomeratic sandstones, dark gray <br />carbonaceous shale, and numerous coal seams. Five coal seams are present in the <br />Dakota Sandstone in the permit area, three of which are of minable thickness. <br />Underlying the Dakota Sandstone is the Lower Cretaceous Burro Canyon Formation, <br />which is approximately 150 feet thick. It consists generally of two beds of <br />conglomeratic sandstone, each 10 to 40 feet thick, separated by a shale sequence. The <br />lower sandstone of the Burro Canyon Formation contains the only significant ground <br />water accumulations in the permit area. This aquifer lies 90 to 100 feet <br />stratigraphically below the lowest coal seam to be mined. The applicant has monitored <br />wells BW -1, BW -2, and BW -3 to establish pre - mining water levels and quality. Yield <br />from these wells vary from zero to three gpm. No other ground water development has <br />taken place in the vicinity of the permit area. <br />Five springs or seeps have also been located in and around the permit area at the <br />contact of the Burro Canyon and the underlying Morrison Formation. The discharge of <br />these springs is generally so slight as to be immeasurable, and most have been dry <br />since the second quarter of 1989. Specific conductivity of the water varies from <br />approximately 1100 to 1700 umhos /sec. <br />Potential impacts to ground water from the operation include: <br />- Lowering of water levels in the Burro Canyon aquifer; <br />- Contamination of the Burro Canyon aquifer; <br />- Lowering of water levels in alluvial aquifers of Bramiers Draw and <br />Section 33 Creek; <br />- Contamination of the same alluvial aquifers. <br />As described above, relatively continuous sandstones in the lower Burro Canyon <br />Formation yield small amounts of water to wells and are the source of several small <br />springs and seeps in and around the permit area. Along with the rest of the <br />stratigraphic section, this formation dips to the north at 2 to 3 degrees in the area. <br />Discharge to the surface occurs at the seeps mentioned above. The formation does not <br />outcrop within the permit area. Recharge to the Burro Canyon likely occurs well south <br />15 <br />