2011-10-31_REVISION - M1976009HR (7)

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RULE 6.5 GEOTECHNICAL STABILITY EXHIBIT INTRODUCTION: In the mid- 1990's amendment, information pertaining to stability was meager. There was considerable discussion with the application reviewer as to whether it should be provided or not. The application reviewer decided it was not needed because of the character of the site. This character is not conducive to stability problems and historically what problems have occurred were small and highly localized. Furthermore, because of the lack of instability producing structure of the rock being mined, attempts to map and define the complete variety and configuration of the melange of huge "chunks" of granite would be virtually impossible. Hundreds or even thousands of cores would be needed, both vertical and angled, to define the structure and search for possible weak zones. In this situation, it was considered more useful to simply deal with problems as they occur and to mine in such a way as to limit the possible development of large scale problems. Thus, other than the blasting plan, much of this exhibit discusses the overall structure as it is known and relies heavily on past experience with mining at this site over several decades. Furthermore, MSHA carefully watches that mining techniques and the resulting topography does not create hazardous conditions. Unlike other kinds of quarries that mine sedimentary rocks (sandstone, limestone, dolomite, etc.) this site mines granite and there are no sedimentary beds on the site or even near the site. Such characteristics as bedding planes, clay seams, extensive water seepage to create saturated slip zones are not found here. Of course, any time mining is occurring in a steep slope mountainous area slope failures and landslides are a risk. Thus the real question becomes the probability that such would occur. Here, because the structure underlying the surface is a melange of generally old, hard igneous and metamorphic rocks devoid of an identifiable structural pattern the probabilities are low. This is the very reason why these issues were not more extensively examined in the last amendment. (1) On a site - specific basis, an Applicant shall be required to provide a geotechnical evaluation of all geologic hazards that have the potential to affect any proposed impoundment, slope, embankment, highwall, or waste pile within the affected area. The Applicant may also be required to provide a geotechnical evaluation of all geologic hazards, within or in the vicinity of the affected lands, that may be de- stabilized or exacerbated by mining or reclamation activities. The Menzer Quarry has been in operation for several decades. The mining occurs in a part of the Pikes Peak Granite that has been modified extensively by a special kind of geological process. This modification broke the formation into a large number of very large "blocks" of rock often hundreds of feet across. In gross form, the deposit looks like a very deep and large pile of various kinds of rocks of huge dimensions mixed together as if pushed into a pile by a giant bulldozer. In fact, the bulldozer was Pikes Peak. Between about 20 million and 3 million years ago, crustal extension to the west of the Pikes Peak region created huge graben in the high mountains. These features include the San Luis Valley, and the South, Middle, and North Parks that run along a general north -south line through the Rocky Mountains. The San Luis Valley and, as some believe, South Park may be related to the Rio Grande Rift that is mainly in New Mexico. As this extension occurred, the mountain ranges to the east of the collapsing crust were forced to the east. Some of the most dramatic movement occurred in the Pikes Peak region. As the ancient 1.1 billion year old batholith that forms Pikes Peak and much of the surrounding land Menzer Quarry Corrective Action Amendment Rule 6.5 October 2011 Page 1