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area can and is controlled by a locked gate to prevent casual or <br /> accident access. <br /> 6. 3 Exposure of personnel to outdoor winter conditions <br /> would include risks of frostbite, colds, bronchitis, pneumonia, <br /> hypothermia. <br /> 6.4 Personnel required to work on sealing mine portals <br /> during winter months will be exposed to dangerous travel conditions <br /> on icy and/or snowpacked roads, some of which have not been <br /> walT:talned in many years. All roads are subject to avalanche <br /> dangers. Some of the roads are in areas where Mid-Continent has <br /> never controlled avalanches in the past, and Mid-Continent does not <br /> know what the appropriate avalanche controls would be. <br /> 6.5 Personnel will be exposed to hazardous work site <br /> conditions, such as steep slopes on the North face of Huntsman <br /> Ridge, icy/snowy surface conditions, and inclement weather <br /> exposures on the surface. Portal work will be subject to 130 mine <br /> slopes and icy conditions in the mouths of the portals. Extreme <br /> slip-and-fall conditions will be present. Freezing and thawing <br /> will intensify the hazard of weathered rock in the roof of the <br /> portals increasing the possibility of roof falls even with <br /> additional temporary support. <br /> 6. 6 During winter months, cold air enters the Dutch <br /> Creek Mine via the RTP adits, it rises through the mine and <br /> exhausts out the higher outcrop portals. During the summer this <br /> natural flow is reversed. Therefore, there is a possibility of <br /> hazardous levels of methane occurring during portal sealing work <br /> areas during the cold, winter weather that does not exist in the <br /> more accessible, summer months. <br /> 6.7 Portal seals constructed by bulldozing <br /> incombustible materials into the portals will not be satisfactory. <br /> It will be impossible to avoid including snow and ice, that will <br /> subsequently melt, with the soil and natural materials used in such <br /> sealing. <br /> 6.8 Portal seals constructed of block material during <br /> winter months will not be satisfactory because of the constant <br /> subfreezing and frequent subzero temperatures. These consistently <br /> low temperatures will freeze the mortar almost immediately, and it <br /> will subsequently thaw and crumble without properly setting. <br /> 6.9 Portal seals constructed by shooting down roof will <br /> require working under and drilling into potentially dangerous roof <br /> that is weathering by virtue of winter freezing and thawing, access <br /> by additional mobile equipment under winter hazardous conditions, <br /> and handling explosives under increased difficulties and hazardous <br /> conditions. <br /> Mines Sealing g 75.1711 <br /> D RAF T <br /> MSHA Modification - 5 - 13-Nov-92 <br />