2011-10-31_REVISION - M1976009HR (7)

Home Browse Search

was pushed eastward it encountered resistance from mainly Paleozoic and Mesozoic sedimentary beds. Where the Precambrian granites and the more recent sedimentary rocks met, many of the sedimentary rocks were lifted upward and rotated so the previous flat -lying beds steeply dipped to the east or even became vertically oriented. In some places, such as Cheyenne Mountain located to the south of the Menzer Quarry, the granite rode over the sediments, flipping them over and then often burying them under thousands of feet of granite. This kind of thrust faulting is more commonly seen in Wyoming and is unusual along the Colorado mountain front on the east side of the Rockies. On the southeast side of Pikes Peak where the Menzer Quarry is located, the eastward movement of Pikes Peak essentially plowed the earth in front of it. This "plowing" extensively fractured the granite into huge blocks or chunks that were then tumbled together in a highly variable agglomeration of most if not all the variety of rock types found in the Pikes Peak granite. As a result of erosion during primarily the Pleistocene, these rocks were exposed. As expected, the on -site rocks vary widely from place to place and the entire mass is devoid of any identifiable structure. Although this makes mining difficult because the quality of the rock varies greatly over sometimes short distances, it also has the advantage in that the resulting topography is very stable. With so much variety, weak rocks that, in larger masses, could be prone to failure are held in place by surrounding hard rocks. In many of the exposed walls at the Menzer Quarry this "structure" is quite visible. No major faults extend through the area, although to the east were the granites and the sedimentary beds meet, there are probably large faults. The more or less linear form of Turkey Creek Canyon could be a fault line, but no information has been found to verify that the canyon is anything other than a steep, stream cut canyon bounded on the east by very resistant granites that form the towering cliffs in the canyon downstream from the quarry. Even if there was a fault there, it would only encounter the quarry area on the far eastern edge. Although features have been found in the course of the mining that look like faults, these often turn out to be comparatively short boundaries between two very large blocks of rock. Thus, these are more like joints than faults. Sometimes, the joints generate a small amount of water when they are exposed. But these seeps quickly dry out and the few that persist with weeping show no signs of motion between adjacent blocks of rock. This is consistent with experiences in drilling water wells in the surrounding countryside. The wells rarely produce more than a very few gallons per minute and many of those soon go dry. As is evident in examining the quarry, there is not much water contained in this jumble of rock. What water there is tends to be confined to small joints between blocks. Furthermore, encountering wet rock during the mining does not occur. (2) On a site - specific basis, an Applicant shall be required to provide engineering stability analyses for proposed final reclaimed slopes, highwalls, waste piles and embankments. An Applicant may also be required to provide engineering stability analyses for certain slopes configuration as they will occur during operations, including, but not limited to embankments. Information for slope stability analyses may include, but would not be limited to, slope angles and configurations, compaction and density, physical characteristics of earthen materials, pore pressure information, slope height, post - placement use of site, and information on structures or facilities that could be adversely affected by slope failure. Shortly after the amendment in the mid- 1990's, mining on the south side of the quarry produced a benching pattern with walls 50 to 60 feet high and benches about 25 to 30 feet wide. Menzer Quarry Corrective Action Amendment Rule 6.5 October 2011 Page 2