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i <br />CNAPTERTHREE Affected Emlironment <br />3.5 METEOROLOGY AND AIR QUALITY , <br />3.5.1 Regional Overview ' <br />This section presents information on the climate, a brief overview of the regulatory requirements <br />related to air quality permitting, and information concerning the existing air quality in the project <br />region. <br />3.5.2 Climate , <br />3.5.2.1 Study Area <br />The proximity of the mountains exerts a strong influence on the climatology and meteorology of <br />the study area. The study area (comprised of the northern and western portions cf the White <br />River Resource Area) is chazacterized by hot, dry summers and cold, dry winters. Air movement , <br />at this latitude is predominantly from the south southwest. However, prevailing ~~vind and <br />dispersion patterns are modified by the complexity of the terrain. Significant diumal drainage <br />flows (slope and valley winds) can be expected within the study area. For example, <br />meteorological data at the Parachute Site indicates a very strong westerly component. <br />The study azea is subject to prolonged and intense inversions, which occur in both winter and <br />summer (BLM 1982). Inversions aze most severe in the winter when snow cover and shorter <br />daylight hours combine to intensify the difference between cold air at the surface and the warmer <br />air mass aloft. Inversions aze more frequent and persistent in valleys, such as the Piceance Creek , <br />Basin and the Parachute Creek valley, where air movement is relatively restricted. In general, <br />the depth of the colder air defines the mixing height and determines the volume itt which air <br />pollution emissions can be confined. Prolonged inversion conditions with low mixing heights <br />create a buildup of pollutants confined in a smaller volume. During summer, the early morning <br />inversions are generally dissipated by sunshine warming the air near the ground. During the. ' <br />winter, inversions may persist throughout the day. <br />3.5.2.2 Project Area: Piceance Site/Pipeline/Parachute Site , <br />The climate of the Project Area is best represented by data from the Little Hills meteorological <br />monitoring station (Station No. 55048) between 1948 and 1991. The station is located <br /> <br />approximately 8 miles northeast of the Piceance Site at latitude 40.00°N, longitude 108.12°W, , <br />and elevation 6,140 feet above msl. <br />The climate of the Project Area is classified as semi-and continental with a growing season of <br />approximately 100 days (BLM 1982). This type of c]imate is chazacterized by lo~v relative <br />humidity, sunny days and clear nights, low precipitation with high evaporation, anal large diumal <br />temperature changes. <br />, <br />The Project Area receives an average of 12 to 14 inches of precipitation a year, with total <br />precipitation ranging from as much as 20.37 inches (1986) to as little as 8.53 inches (1966). <br />Spring and late summer are the wettest periods of the yeaz. August is the wettest month with an <br />3-22 Meteorology and Air Quality <br />