2010-12-30_PERMIT FILE - P2010026 (5)

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TABLE 2 (continued) RD&D LEASE COC-69166 SOIL INTERPRETATIONS 12 Hydrologic Group Classification of Soils: Hydrologic soil groups are used in watershed planning to estimate runoff from rainfall. Soil properties are considered that influence the minimum rate of infiltration obtained for a bare soil after prolonged wetting. These properties are: depth of seasonally high water table, intake rate and permeability after prolonged wetting, and depth to a very slowly permeable layer. The influence of ground cover is treated independently - not in hydrologic soil groupings. The soils have been classified into four groups, A through D. The individual classifications are taken from the most current official soil series "Form 5" sheets. Statements in parentheses following the definitions may be helpful to soil scientists wishing to place soils into hydrologic groups using the soil classification system. A. (Low runoff potential). Soils have high (rapid) infiltration rates even when thoroughly wetted and consist chiefly of deep, well to excessively drained sands or gravels. These soils have a high rate of water transmission. (Includes Psamments except those in Lithic, Aquic, and Aquodic subgroups; soils in Grossarenic subgroups of Udults and Udalfs, and soils in Arenic subgroups of Udults and Udalfs except those in clayey or fine families). B. (Moderately low runoff potential). Soils have moderate infiltration rates when thoroughly wetted and consisted chiefly of deep, well to excessively drained sands or gravels. These soils have a high rate of water transmission. (Soils other than those in groups A, C, or D). C. (Moderately high runoff potential). Soils have slow infiltration rates when thoroughly wetted and consist chiefly of soils with a layer that impedes downward movement of water, soils with moderately fine to fine texture, soils with slow infiltration due to salts or alkali, or soils with moderate water tables. These soils may be somewhat poorly drained. This category also includes well and moderately well drained soils with slowly and very slowly permeable layers (fragipans, hardpans, hard bedrock, and the like) at moderate depth (20-40 inches). (Includes soils in Albic or Aquic subgroups; soils in Aeric subgroups of Aquents, Aquepts, Aquolls, Aqualfs, and Aquults in loamy familities; soils other than those in group D that are in fine, or clayey families except those with kaolintic, oxidic, or halloystic mineralogy; Humods and Orthods; soils with fragipans or petrocalcic horizons; soils in shallow families that have permeable substrata; soils in Lithic subgroups that have rock that is pervious or cracked enough to allow water to penetrate). D. (High runoff potential). Soils have very slow infiltration rates when thoroughly wetted and consist chiefly of clay soils with a high swelling potential, soils with a permanent high water table, soils with a claypan or clay layer at or near the surface, soils with very slow infiltration due to salts or alkali, and shallow soils over nearly impervious material. These include Aquods; soils in Aquents, Aquepts, Aquolls, Aqualfs, and Aquults except for aeric subgroups in loamy families; soils with natric horizons; soils in Lithic subgroups that have impermeable substrata; and soils in shallow families that have impermeable substrata). 13 Understory Vegetation: The potential production of the native understory vegetation in normal years in pounds of air-dry vegetation per acre. Data taken from Soil Survey of Rio Blanco County (Tripp et. al. revised 1992). 14 Organic Matter Percent: Organic matter percent of the "A" horizon surface layer. Data taken from Table 10 of the Soil Survey of Rio Blanco County (Tripp et. al. revised 1992). 1s Thickness of "A" horizon surface layer taken from soil map unit and soil series descriptions of the Soil Survey of Rio Blanco County (Tripp et. al. revised 1992). 0 01 0 21