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RULE 2 PERMITS <br />Wind <br />The synoptic flow in the area is characterized by prevailing westerly winds, which influence air quality in <br />the region. The direction and speed of the winds are greatly affected by the local topography. <br />The general area contains two large drainage basins: the Yampa River Basin and the Williams Fork River <br />drainage system. The Yampa Valley forms a broad canyon which channels the airflow into an east-west <br />orientation reflecting upslope and downslope motion. Similar upslope-downslope wind flow exists in the <br />Williams Fork Valley. The flow draining this Valley is directed northwardly along the high ground west <br />of Craig prior to joining the main stream flowing up and down the Yampa Valley at the end of the ridge. <br />The high frequency of near-calm conditions exists because of the protection afforded by the local terrain <br />in most of the valleys. These conditions generally occur at night and in the early morning. The strongest <br />winds in the area can be expected during the winter and early spring, especially in March, and briefly <br />during summer thunderstorms. <br />The prevailing winds over most of the permit area will be from the southwest at an average speed of <br />approximately 8 to 9 miles per hour; some 10 to 15 percent of the time the wind will blow out of the <br />northeast. Strong winds will occur due to cold fronts and thunderstorms moving through the area, but fair <br />weather winds will rarely exceed 20 to 25 miles per hour. <br />MeteoroloLyical Work at Colowvo <br />Site specific meteorology and total suspended particulate analyses for the Colowyo operation are set forth <br />in Exhibit 8, Air Quality Information under the title of "Report of Site Meteorology and Total Suspended <br />Particulate Studies." This one year baseline monitoring program was conducted by Western Scientific <br />Services, Inc. of Fort Collins, Colorado during 1976. <br />Site-specific precipitation data obtained at the Colowyo operation are presented in Table 2.04.8-7, <br />Monthly Precipitation - Colowyo Permit Area. <br />Representative wind roses are set forth in Figure 2.04.8-1, Wind Rose - Mine Site and Figure 2.04.8-2, <br />Wind Rose - Gossard Loadout. <br />Rule 2 Permits 2.04.8-2 Revision Date: 6/23/08 <br />Revision No.: MR-91