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eh <br />ESPEY, HUSTON & ASSOCIATES, INC. <br />• <br />Soils with a low runoff potential have high, or rapid infiltration rates <br />even when thoroughly wetted, and consist mostly of deep, well to excessively <br />drained sands or gravels. They also have a high rate of water transmission. <br />Soils with a moderately low runoff potential have moderate infiltration <br />rates when thoroughly wetted and consist mainly of moderately deep to deep, <br />moderately well drained to well drained soils with moderately fine to moderately <br />coazse textures and moderately slow to moderately rapid permeability. They also <br />have a moderate rate of water transmission. <br />Soils with a moderately high runoff potential have slow infiltration rates <br />when thoroughly wetted and consist mainly of soils with a layer that impedes <br />downwazd movement of water, soils with moderately fine to fine texture, soils with <br />• slow infiltration due to salts or alkali, or soils with moderate water tables. They <br />may be somewhat poorly drained. They are also we]] drained and moderately well <br />drained soils that have slowly permeable and very slowly permeable layers (hazd- <br />pans, hazd bedrock) at moderate depths 20 inches to 39 inches. <br />Soils with a high runoff potential have very slow infiltration rates when <br />thoroughly wetted and consist mainly of clay soils with a high swelling potential; <br />soils with a permanent high water table; soils with a claypan or clay layer at or neaz <br />the surface; soils with very slow infiltration due to salts or alkali; and shallow soils <br />over neazly impervious material. They also have a very slow rate of water <br />transmission. <br />In Table I-12, the estimates of permeability aze for soils in place and aze <br />based on the structure, texture, and porosity of the soil material and on field <br />observations. The available water capacity, given in inches per inch of soil, is the <br />capacity of the soil to hold water available for most plants. It is commonly defined <br />as the difference between the amount of water in the soil at field capacity and the <br />• amount at wilting point. The shrink-swell potential is an indication of the volume <br />I-83 <br />