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• Table 8-3 presents site-specrfic wind direction data between January 1981 and December 1986 and between <br />January 1992 and December 1993 (eight complete years). The winds trend from east-southeast to west-northwest <br />which conforms with the general topography of the area. Down valley flow (occurrences from the east-southeast) <br />accounted for 25.2 percent of the recorded hourly averages. Up valley flaw (occurrences from the west-northwest) <br />accounted for 11.4 percent of the recorded hourly averages. Both of these percentages apply to a relatively narrow <br />corridor (22.5 degrees) of wind direction. By including the 22.5 degree sectors on either side of east-southeast <br />and west-northwest, a broader pattern of wind occurrences is shown. The 67.5 degree sector from east through <br />southeast accounts for 39.4 percent of wind occurrences that could be attributed to down valley flow. The 67.5 <br />degree sector from west through northwest accounts for 30.1 percent of wind occurrences that could be attributed <br />to up valley flow. Together these two opposing 67.5 degree sectors encompass 69.5 percent of the available <br />occurrences. The occurrences recorded as calm consume another 7.0 percent while the remaining 23.5 percent <br />are divided among the other ten 22.5 degree sectors with none exceeding 4.0 percent. <br />Average wind speed at the Seneca II-W Bile for the period of record was 3.5 knots. The maximum wind speed <br />recorded was 58.6 knots. The average maximum wind speed was 15.4 knots, while the average minimum wind <br />speed was 0.17 knots. <br /> Table 8-3 <br /> Percent of Time the Wind Blows from a Given Direction <br />• <br /> <br />N 1.3 E 7.0 S 3.5 W 5.1 <br />NNE 1.1 ESE 25.2 SSW 2.8 WNW 11.4 <br />NE 1.1 SE 7.1 SW 1.9 NW 13.7 <br />ENE 2.4 SSE 4.1 WSW 2.3 NNW 3.0 <br /> Calm = 7.0 <br />The previous discussion of winds presented in "Analysis of the Meteorological and Air Quality Data for the Seneca <br />Mine, January 1978 - December 1978", although written for that area and local terrain, provides general <br />characteristics and trends that could be applicable to the Yoast Mine area. The obvious differences are valley <br />orientation and specrfic topographical characteristics. The Seneca II-W meteorological site data was obtained at <br />valley bottom, and showed fairly strict channeling of dawn valley and up valley flows with minor disturbance from <br />the prevailing east-west Yampa River valley winds. The recorded winds collected at the Seneca II-W site support <br />general trends mentioned in the analysis for the Seneca Mine. These results, together with the known wind pattern <br />of the larger Yampa River valley, provide a reasonable long-term assessment of the expected meteorological <br />conditions at the proposed Yoast Mine area. <br />• <br />5 <br />