2011-06-30_REVISION - M2002004 (82)

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GCC Rio Grande, Inc. — Pueblo Cement Plant and Limestone Quarry Exhibit E previously discussed, Exhibit D -2 details the sequencing of backfill, including grading and soil placement along with seeding, that will occur concurrent with mining in each panel. The backfill will be composed of unconsolidated materials and shale that cover the Fort Hays Limestone. The unconsolidated material thickness ranges from approximately 0 feet to approximately 25 feet. Shale up to 15 feet in thickness underlies the unconsolidated material in areas along the eastern edge of mine plan boundary; however, based on exploration data, shale does not appear to occur in the subcrop over much of the resource area. In general, backfilled areas will be about 10 to 20 feet below existing surface elevations. Once backfill grading is completed, subsoil and topsoil will be spread followed by seeding, fertilizing, and mulching. Highwalls will be dozed into the pit to blend with the surrounding topography. Graded slopes will be no steeper than 4h:1 v, and main drainages from the reclaimed areas will be re- established. Highwalls at the northern edge and the sides of the earthen incline will be permanently stabilized by placing a mixture of spoil and soil materials on the final slopes. The spoil/soil mixture's content will be 70 percent or less for rock, and 30 percent or more for soil. Final highwalls will be sloped not to exceed 4h:ly. The graded backfill will be ripped with equipment and implements capable of penetrating a minimum of 12- inches deep on 18 -inch centers to alleviate compaction and reduce slippage planes between the backfill /soil interface. Once grading is completed, topsoil and subsoil materials will be spread followed by seeding, fertilizing, and mulching, when applied. Exhibit D -1 illustrates topography at the end of the first eight years of mining operations. Exhibit D -2 illustrates the sequence and status of reclamation activities at the end of the first eight years of operation. Final Reclamation Material Balance Exhibit F -1 is the final reclamation surface plan for the quarry area at the end of the 50 -year operating pit life. Using the Suprac Vision mine modeling software, an ultimate pit shell for the entire 50 -year life of mine was developed that incorporated the proposed side slopes in both overburden and limestone. The pit floor was defined by extracting 5 -feet of the Codell Sandstone. With this pit shell and pre- existing topography, a surface -to- surface volume extraction was performed to determine to total bank volume of available reclamation fill. The approximate bank volume of overburden (unconsolidated material and shale) is estimated to be 14.4 million cubic yards. In order to define the final reclamation surface, a 20 percent swell factor was used to calculate the overall volume of material that is anticipated to be placed back into the quarried area over the course of mining. Using this swell factor, the approximate quantity of available reclamation backfill becomes 17.3 million cubic yards. Generalized balanced cross sections depicting the pre- mining topography, ultimate pit shell and reclaimed surface are provided in Exhibit F -2. Although the quantity of material backfilled will vary spatially, the mining and reclamation process is expected to result generally in a fill wedge increasing in thickness to the southeast. Based on this scenerio, a final reclamation surface was modeled given the volume of backfill available. Once complete, the contours were generated from the reclamation surface model and incorporated into the surrounding topography, as shown on Exhibit F -1. Restoration of Arroyos Several arroyos were assessed to determine that cross - sections reflect a broad, shallow area, typical in the upper watersheds. From these assessments, a typical cross section was identified having a trapezoidal shape with a 5 -foot bottom and nearly flat slopes (that is, 20H:1 V). This cross section will convey the 100 -year flood with depths no greater than 3 feet, which reduces flow velocities, shear stresses, and therefore erosive forces. Depending on flow velocity, erosion control measures vary from vegetation for flat slopes (up to 0.5 %), to vegetation and rock for intermediate slopes (from 0.5% to 2.0 %), and Revised June 29, 2011 E -2 Exhibit E — Reclamation Plan