2012-12-20_INSPECTION - M1993041

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OBSERVATIONS PERMIT #: M- 1993 -041 INSPECTOR'S INITIALS: MAC INSPECTION DATE: November 30, 2012 The inspection was conducted by Michael Cunningham of the Division of Reclamation, Mining and Safety (Division). Patrick Fischer and Denise Arthur of CEMEX, Inc. were also present for the inspection. The site is located approximately 2 miles east of Lyons, Colorado. The site is permitted for 1,854.45 acres, of which 464.9 acres are designated as affected area. Only 105 acres may be disturbed by mining at any given time, this does not include other areas of disturbance such as the crusher area, stockpiles, offices, maintenance shop, conveyor, or the fuel station. The approved post mining land use is rangeland. Gen. Compliance With Mine Plan: The site was in operation at the time of the inspection. The Operator mines Limestone from a series of four ridges referred to in the Mining Plan as: Hi -Cal ridge, 2nd ridge, 3rd ridge, and 4th ridge. Mining is currently occurring within the Hi -Cal ridge and the 3rd ridge. The Operator is mining within two pits which are adjacent to one another and area separated by 100 LF. According to the 2012 Annual Report, the pits encompass 80.4 acres. The Operator conducts periodic blasting which results in benches that area approximately 45' in height. Mining is progressing to the north. The blasted material is transported to the crusher facility which is located along the main access road, approximately 3,000 feet south of the pits. After crushing, the material is loaded onto a conveyor and transported south across Highway 66 to the CEMEX cement plant at the Lyons Quarry (M- 1977 -208). The conveyor route is approximately 7,000 LF and was not operating at the time of the inspection. The bedding planes have a north /south strike and dip towards the east. Therefore the pit floors dip towards the east and the highwalls are formed along the north, south and east side of the pits. The Operator has committed to not exceeding a maximum depth of 170' in the Hi -Cal excavation or a maximum depth of 80' in the excavations for the other ridges. Based on the Division's observations, the operator has not exceeded the maximum allowed depths in either of the pits. The main overburden stockpile is located immediately south of the pits and a smaller secondary stockpile is adjacent to the crusher facility. Topsoil has been stockpiled along the east side of the pits and is currently providing a visual barrier between the mine site and County Road 47. The stockpiles are vegetated and stable. The fuel station is located near the entrance to the site; fuel is stored within a secondary containment unit. The Division also visited the office and maintenance shop area; everything was in order and no problems were noted. Hydrologic Balance: The pits collect water from precipitation; the Division observed water in the 3rd ridge pit during the inspection. The water is periodically pumped from the 3rd ridge pit into the Hi -Cal ridge pit where it is used for dust suppression. Since the water remains in the pits for longer than 72 hours, the Operator must account for evaporative depletions. The Operator tracks the consumptive use of water and then makes payments to the St. Vrain and Left Hand Water Conservancy District; water is eventually diverted into the St. Vrain River to replace the evaporative depletions associated with the mining operation. A small wetland area had been identified towards the north end of the site. According to the Operator, the wetlands were formed from water seeping from the irrigation ditch which runs through the north portion of the mine site. The Operator has provided the Division with documentation from the Army Corps of Engineers Page 2 of 5