Final Environmental Impact Statement for Wyoming Interstate Co, Ltd's Piceance Basin Expansion Project under CP05-54.

ENVIRONMENTAL ANALYSIS CHAPTER 3 3.1 Geology 3.0 ENVIRONMENTAL ANALYSIS 3.1 Geology 3.1.1 Geology and Physiography The proposed Piceance Project route would cross parts of three major physiographic provinces: the Wyoming Basin, Southern Rocky Mountain, and the Colorado Plateau (Howard and Williams 1972). The Wyoming Basin Province generally consists of mountain ranges separated by broad basins. The pipeline route crosses a section of the Wyoming Basin known as the greater Green River Basin. The portion of the Southern Rocky Mountains Province that is crossed is an area of moderate relief called the Danforth Hills, but the route mainly crosses alluvial areas. The Colorado Plateau Province is characterized by mesas and plateaus and the southern portion of the pipeline route is located in the Piceance Basin. Table 3.1-1 summarizes by MP the physiographic provinces and geology along the proposed pipeline route. Construction of the proposed project facilities would not materially alter the geologic and physiographic conditions or worsen existing unfavorable geologic conditions in the area. Construction effects would include disturbances to the natural topography along the ROW and aboveground facilities due to grading and trenching activities. Upon completion of construction, WIC would restore topographic contours and drainage patterns as closely as possible to their pre-construction condition. Operation of the pipeline and its associated facilities would not affect the geologic and physiographic conditions in the project area. 3.1.2 Mineral Resources Potentially Exploitable Resources In Colorado, the route crosses areas containing sedimentary rock strata that are productive of oil and gas. The Sand Wash and Piceance Basins primarily produce natural gas from Tertiary and Cretaceous rocks. The route crosses or is in the vicinity of several oil and gas fields including Piceance Creek, Danforth Hills, Big Hole, and Big Hole North (Wray et al. 2002). Most of the route is underlain by strata that are potentially productive of oil and gas. These areas may be potentially capable of producing coal bed methane (EPA 2002). From MP 135.3 to MP 141.7, the proposed project lies within an area of known oil shale-bearing strata of the Green River Formation in the Piceance Basin (Tweto 1979). The proposed project also crosses potential coal-bearing formations located in the Danforth Coal Field (Tremain et al. 1996). The Danforth Coal Field is located in the extreme northeast Piceance Basin and contains coal resources in upper Cretaceous rocks that are potentially mineable from surface or underground mines. In Wyoming, the pipeline route crosses areas that are entirely underlain by strata that are potentially productive ...