The Upper Narrows Tunnel on Highway 160 in southern Colorado has been designed with a unique system of escape adits to provide for life safety in the event of emergencies in the tunnel. The use of adits provides for a higher level of safety in this application than would be provided by the more common ventilation system. A summary of the unique project conditions that facilitate such a system is presented, and the methods of analyses and results of calculations used during the design are reviewed.
Mined land reclamation pennits for open pit mines and quarries often require detailed mine plans showing mine development, phasing, areas of disturbance, and reclamation activities at each stage of development. Slope angles and bench/highwall configurations are critical to the mine plan both for reclamation and for mine economics. However, detailed evaluation of slope stability prior to excavation requires an extensive exploration and testing program followed by detailed engineering analyses which can be both time consuming and expensive to the mine owner. Furthermore, basing slope configurations entirely on predictions requires a relatively high degree of conservatism in the design.An alternative approach is to base slope design on the performance of existing slopes combined with engineering models to extrapolate the observed behavior -the "Observational Approach". A key factor in applying the observational approach is the development of different mine reclamation plans for the range of alternative slope configurations. During the process, regulatory authorities need to be satisfied that a rational approach is used to progressively open the mine without overdevelopment which could potentially compromise reclamation activities. This paper describes the observational approach to mine development and reclamation, and presents a discussion of how the method can be implemented with the use of specific controls to satisfy regulatory requirements. An example project is presented for an open pit aggregate quarry in the foothills of the Rocky Mountains near Denver, Colorado. Details of application of the observational approach to the project are presented including alternative mine configurations, reclamation measures, and regulatory agreements.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.