2019-01-18_REVISION - M1974086 (16)

Home Browse Search

GEOTECHNICAL STABILITY EXHIBIT There are no buildings or any structures outside the permit area which could be affected by the excavation. A minimum 30 foot buffer will be maintained from the permit boundary line to all new excavations. There will be no excavation within 30 feet of the property line. 1. Quarry Slope Stability The Ralston Quarry is entirely contained within a basalt extrusion adjacent to Pierre shale that has been uplifted. Basalt, like what is found in this quarry, is highly competent material that facilitates mining to very steep slopes. The south, north, and east slopes of the quarry are entirely contained within the basalt, and are therefore limited in their slopes by the basalt's geotechnical properties and local jointing. On the west slope,the basalt-shale contact dictates the limits of excavation and permanent slopes. Brierley and Associates of Golden, CO performed a site specific analysis of the slope stability at Ralston Quarry. This information can be found in Appendix 2. All mining and reclaimed slopes within the quarry itself will be based on these reports and analysis. See Map F-I for details of the final slope configurations within the quarry. Asphalt Paving Co. will adjust bench heights and widths within these limits to create slopes that are aesthetically pleasing in reclamation. Also, internal slopes maintained during mining will vary as necessary to facilitate mining, and to maintain safety standards. The slopes shown on Maps C-2 and F-1 are plan views of the maximums and minimums determined by Brierley, and are used to illustrate the maximum possible build out of the quarry. The final slopes will vary and adjust to the on-site geology. 2. Blasting Seismic measurements are taken each year, and a report of these measurements is provided to Asphalt Paving Co. A copy of the most recent report can be found in Appendix 3. 3. North Platform Backfill Ralston Quarry GrM 1e ki i and Asw intm PLLC January 2019 GS-1