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i <br /> ' EXHIBIT I - SOILS INFORMATION <br /> The soils within the permit area occur on nearly level landscapes <br /> and are generally deep, greater than 40-60 inches , and poorly <br /> drained . The soils are underlain by gravels . The gravel averages <br /> 20 feet deep throughout the permit area . <br /> Three different soil mapping units occur within the permit area . <br /> They are the Altvan loam, Aquolls and Aquents ( gravelly <br /> substratum) , and the Heldt silty clay . The soils map is <br /> illustrated on Map I- 1 . <br /> A detailed description of the soils mapping units as prepared by <br /> the soil conservation office is provided below. <br /> ' I- Altvan loam, 0 to 1 percent slopes . This is a deep , well <br /> drained soil on terraces at elevations of 4 , 500 to 4 , 900 feet . It <br /> ' formed in old alluvium deposited by the major rivers . Included in <br /> mapping are small areas of soils that show evidence of poor <br /> drainage . Also included are small , long and narrow areas of sand <br /> and gravel deposits . <br /> 1 Typically the surface layer of the Altvan soil is grayish brown <br /> loam about 10 inches thick. The subsoil is brown and light <br /> yellowish brown clay loam and sandy clay loam about 15 inches <br /> thick. The substratum is calcareous loamy sand about 6 inches <br /> thick over gravelly sand . <br /> ' Permeability and available water capacity are moderate . The <br /> effective rooting depth is 20 to 40 inches . Surface runoff is <br /> slow, and the erosion hazard is low. <br /> ' This soil is used almost entirely for irrigated crops . It is <br /> suited to all crops commonly grown in the area , including corn, <br /> ' sugar beets , beans , alfalfa, small grain, potatoes , and onions . <br /> An example of a suitable cropping system is 3 to 4 years of alfalfa <br /> followed by corn, corn for silage, sugar beets , small grain, or <br /> ' beans . The high clay content and the rapidly permeable substratum <br /> slightly restrict some crops . <br /> This Altvan soil has fair to good potential for urban and <br /> recreational development . The chief limiting soil features for <br /> urban development are the shrink-swell potential of the subsoil as <br /> it wets and dries and the rapid permeability of the sand and gravel <br /> substratum. Septic tank absorption fields function properly , but <br /> in places the substratum does not contain enough fines to properly <br /> filter the leachate . Sewage lagoons require sealing . Lawns , <br /> shrubs, and trees grow well . Capability subclass Its irrigated . <br /> ' I- 1 <br />