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2 <br />The authors reviewed this preliminary information, and later that same day, traveled to <br />Colorado Springs, Colorado, in order to be available for site visits and meetings on <br />December 4, 2008. On the morning of December 4, 2008, they met Messrs. Stefansky <br />and Schroeder and proceeded to the mine site. <br />MSHA issued an imminent danger order under a section 107(a) of the Mine Act, and <br />roadways to the areas of active mining at the pit floor, the drill bench, and a roadway to <br />the top of the pit were closed from entry and blocked with berms prior to MWGED's <br />site visit. <br />DISCUSSION <br />The following information was collected through conversations with company <br />personnel; an examination of the quarry pit and surrounding area; a review of pertinent <br />data and documents obtained from the mine operator, the Colorado Geological Survev <br />(CGS) and the MSHA mine database; and a review of media reports, photos of the site <br />and technical data available on the internet. <br />Mine Location and Production Historv <br />The Pike View Quarry is located at the northwest limits of the City of Colorado Springs, <br />Colorado, about 3 miles to the west of the intersection of Interstate Route 25 and <br />Woodmen Road. The quarry has been operated by a succession of several owners since <br />about 1904, producing crushed limestone aggregate. It was operated intermittently <br />until the 1950's, but from the late 1950's onward, production increased with demand for <br />construction aggregates associated with the construction of the nearby Air Force <br />Academy and suburban development in the area. The quarry employs about 20 <br />persons, and according to the CGS, produces about a million tons of crushed limestone <br />products per year. <br />Mine Operation History <br />The limestone was mined from the lower slope of a 1,500- to 2,000-foot-high ridge that <br />forms a part of the eastern front of the Rampart Range of the Rocky Mountains, as <br />shown in Figures 1 and 2. The natural slopes that were mined were inclined between <br />about 2 and 2.5 horizontal feet to 1 vertical foot (2H:1V to 2.5H:1V). The limestone was <br />quarried from the slope in 30-foot-high cuts by drilling and blasting each cut then <br />excavating the shot material with a front-end loader. The current highwall design has <br />30-foot-wide catch benches spaced about 30 feet vertically with slopes about 75 degrees <br />from horizontal between benches. The design produces an overall slope angle of about <br />1.2H to 1V. In recent years, the quarry operations had progressed to the gentle slope at <br />the foot of the ridge, so the mining transitioned to a pit operation, continuing to use 30- <br />foot-wide benches spaced at about 30 feet horizontally.