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Researchers from the National Institute for Occupational Safety and Health (NIOSH) Spokane Mining Research Division (SMRD) are evaluating the comparative performances of ground convergence monitoring methods currently utilized in underground mining. A portion of this research is exploring applications of photogrammetry for periodic visual assessment of slow-converging ground. This paper describes the photogrammetric systems evaluated, including their components and methodology. These systems include light-weight equipment easily carried by a single individual traversing rough terrain in underground mine environments. This study demonstrates how photogrammetric methods may complement or replace existing underground convergence monitoring techniques on the basis of time and personnel requirements, equipment cost and robustness, and overall data quality. This research supplements previous studies into photogrammetric and laser scanning methods, and enhances understanding of how digital technology may be utilized to maximize safety in underground excavations. NIOSH SMRD is committed to improving workforce health and safety through innovative research and applications of technology.

Corrosion of ground support can lead to falls of ground, posing a significant risk to miner safety. To address this problem, the Spokane Mining Research Division of the National Institute for Occupational Safety and Health is investigating ground support corrosion at the Greens Creek mine, located near Juneau, Alaska, United States of America. Field and laboratory studies include surveys of weld-wire mesh corrosion, rock mass conductivity measurements, and sample analyses using a scanning electron microscope, energy dispersive spectrometry, and Fourier transform infrared spectrometry. Current field studies demonstrate a correlation of rock mass conductivity to the degree of weld-wire mesh corrosion and the relationship of ground conductivity surveys to support corrosion potential. Laboratory analyses of mine samples identify the presence of sulphate, which is a determinant for sulphate reducing bacteria activity. Identification of sulphate reducing bacteria (SRB) would provide evidence for microbial influenced corrosion in this mine. Ongoing research is evaluating methods of SRB inhibition. These results provide engineers with a means to map corrosion potential of the rock mass, and identify a number of paths for design of focused mitigation efforts for problem areas. Keywords: corrosion, sulphate reducing bacteria (SRB), microbial influenced corrosion (MIC), resistivity, safety