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Environmental Assessment <br /> Coal conveyors are commonly constructed with a supporting service road to facilitate operations and <br /> maintenance. Assuming a modest 50-foot-wide disturbance corridor to construct a conveyor for the <br /> approximately six-mile length of alternatives 6, 7, and 8, ground disturbance would be approximately <br /> 36.4 acres of permanent impact, an impact nine times greater than the Proposed Action. It is inaccurate to <br /> claim that aerial coal conveyors are "quiet."While there have been some technological advancements to <br /> mitigate noise generated from coal conveyors, several studies referenced below identify coal conveyors as <br /> one of the noisiest pieces of equipment at an underground coal mine. <br /> The following information is excerpted from Conroy et al. (2014)in a United States Patent Office filing: <br /> "Coal conveyors are widely used in the coal mining industry. They are used, for example,to convey raw <br /> coal or coal ore stones. Coal conveyors can save labor and improve efficiency by moving large volumes <br /> of material. A common type of coal conveyor is a belt conveyor. Belt conveyors typically include a long <br /> belt supported by a support structure, such as a metal frame. Rollers often are disposed at least at ends of <br /> the system. The belt is looped around each of the end rollers, one or more of which is powered to drive <br /> the belt across the metal frame,thereby moving the material. <br /> Typical coal conveyors can be expensive to implement. For example, a typical truss conveyor often has a <br /> large amount of structural steel. Typical coal conveyors also can be difficult to install. Because they are <br /> disposed on the ground and extend over a long span, it can be difficult to traverse roads and rough terrain. <br /> Installation can sometimes require the use of longer, alternative routes to avoid difficult to traverse areas. <br /> Coal conveyors also can have a significant environmental impact, especially relating to the generation of <br /> noise. <br /> In a study presented at Acoustics 2004 (Brown 2004), Brown concluded the following; "Large, outdoor <br /> belt conveyor systems for bulk materials are major sources of industrial noise and frequently become an <br /> environmental emissions issue for many existing and proposed plants. Deficiencies in the industry's <br /> understanding of the complex,underlying conveyor noise generating mechanisms has meant there are <br /> relatively few practical and cost-effective noise management strategies."In a"Coal Mining Planning and <br /> Design Institute, Survey Report" (2012),it was estimated that average noise generated by a belt conveyor <br /> system is about 89 decibels (dB). Elevating that continuous (day and night)noise 10-20 feet above the <br /> ground and along the mesa top east of Hay Gulch would serve to unnecessarily expand noise impacts to <br /> both area residents and wildlife. <br /> From a logistical standpoint, it would be unreasonable to assume that a feasible alignment and associated <br /> ROW could be obtained;then the conveyor constructed before the King II current coal reserve is <br /> exhausted. The commenter acknowledged this fact in the following statement: "The issue that GCC <br /> Energy has is that they do not have permission to mine coal in the lease modification or the exploration <br /> area. This would leave them about 2.67 million tons to mine. This situation is a time problem given the <br /> schedule for permit modification assuming the lease modification can be issued within the next year." <br /> The reasons for eliminating this alternative include the following: <br /> ■ Economically infeasible;the commenter acknowledged, "It is unlikely that use of a conveyor <br /> would be lower cost as compared with over-the-road or off-highway trucks on a single use road." <br /> DOI-B LM-CO-S010-2011-0074-EA <br /> September 2017 <br /> -55- <br />