1998-01-20_REVISION - M1977342 - Laserfiche WebLink

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0 • route and consist of meadow and meadow/shrub types. For perspective, the disturbance and alteration of the approximate 70 acres will amount to approximately 0.003 percent of the total habitat area within the upper Williams Fork River valley. In reality, because of the configuration of the conveyor and access road, less than 50 percent of the 70 acres actually will be disturbed. Communities and habitats similar to those along the conveyor route are common and widely distributed throughout the Williams Fork River valley. In the short-term (<15 years), clearing the conveyor right-of-way in lodgepole pine and mixed conifer stands will result in conversion of these habitats to grass/forb communities. In the long-term (>15 years), the conveyor corridor will likely be maintained as a shrub/seedling seral stage. These changes will favor species adapted to grass/forb types and early seral stage forests (elk, deer, Townsends solitaire, and white-crowned sparrow) to the detriment of species requiring mature confer forests (American marten, southern red-backed vole, northern three-toed woodpecker, hairy woodpecker, and mountain chickadee). • Construction of the conveyor will include installation of 17 overpass and underpass wildlife crossing structures along its length to facilitate movement. Underpasses will be located at trestles where the conveyor line crosses drainages and wetlands. One underpass would be a culvert-type where the line crosses the maintenance road; similar to the underpass used with the present railroad route. Underpass crossing structures will maintain vertical clearances between 6-14 feet in height and horizontal clearance of 15-50 feet. Overpass structures will be constructed as semi-circular earthen ramps bisected by the conveyor. Each ramp will be a minimum of 20 feet wide with at least one foot of topsoil placed over the structure. The approach ramps will be constructed to fan out 180 degrees at the toe of the fill slope. The overpass structure will be revegetated. Crossing structures will be located at points where existing game trails suggest the heaviest usage by large mammals and other species. During the route clearing phase and construction of the conveyor extensive human activity and use of heavy equipment likely will cause non-sedentary species to avoid those areas of activity during periods of activity. Likewise, newly constructed underpasses and overpasses probably will be avoided until construction ceases, • revegetated areas begin to mature, and animals become familiar with the sites.