2012-01-06_PERMIT FILE - C1982057 (27)

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• Wind Speed and Wind Direction As previously noted, seven complete years of meteorological data is available for the proposed Seneca II-W Mine area. No wind speed or wind direction data is available from the Hayden Station. The nearest station for which the National Climatic Center does report surface winds cannot be relied upon to provide a reasonable indication of winds at the proposed Seneca II-W Mine site. This is due mainly to the fact that the surface winds are highly dependent upon local topography. A discussion of wind patterns at the original Seneca Mine meteorological monitoring site was presented in a report entitled "Analysis of the Meteorological and Air Quality Data ~' for the Seneca Mine, January 1978-December 1978", submitted to Peabody by Western Scientific Services, Inc., Roy M. 8arne s. The discussion on winds from that report is presented below. "There are two preferred wind directions at the Seneca Mine site from which the wind blows 80 percent of the time. This is induced by the local topography, • i.e., the north south oriented valley as shown in Map 1. During the night as the earth's surface cools by radiation, the lowest level of air also cools. As it becomes denser than the upper level air, it uncouples from the upper level synoptic wind regimes whose patterns are controlled by broad scale pressure fields. This cool air layer, due to its increased density, wi 11 flow downhi 11 or down valley at the Seneca Mine which i s represented by southerly wind directions. A majority of the nights during the year show this drainage flow as a preferred wind direction. The other wind direction commonly exhibited at Seneca Mine is up valley flow or winds from the north-northwest. The predominant wind direction in the annual data set for neutral stability conditions which are typical of synoptic events (Figure SC) is north-northwest. Historical data from the Hayden power plant located to the west of the Seneca Mine valley, indicated the predominant synoptic wind direction to be westerly at the surface due to the terrain effects of the Yampa River valley. Thus, the terrain effects tend to channel the • prevailing synoptic west an d southwest winds to parallel the east west orientation of the Yampa River valley. As the winds enter the n orth end of the 5