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• 5.2.2 Loadout The unit train Loadout facility is located at a site adjacent to the Roaring Fork River which meets the criteria for an alluvial valley floor (AVF). These criteria include the presence of unconsolidated stream-laid deposits holding streams with sufficient water for subirrigation or flood-irrigation for agricultural activities. A soil survey and ground water well installation on the site confirm the presence of unconsolidated alluvial material at least 40 to 50 feet below the surface. The topsoil material consists of about 12 inches of sandy loam. The lower material consists of a small amount of sandy clay, medium to coarse sands, gravels and boulders. The land on which the Loadout facility is located has been flood-irrigated for production of hay. The land use of the surrounding area has been irrigated hay • meadow, irrigated pasture, and riparian land. The essential hydrologic functions of the AVF are characterized by the surface waters, ground water, and their interactions. The Roaring Fork bisects the permit area and is the predominant surface water feature. The drainage area of Roaring Fork River is approximately 1,400 square miles at the facility. Nearly all the river flow is derived from the upper watershed areas. Less than 5 acre- feet of annual surface runoff in the Roaring Fork is derived from the permit area. Other features which account for little surface runoff are the flay lying terraces of the irrigated areas and the well vegetated river banks. The shallow ground water functions of the AVF at the site are directly related to the surface water functions. The Roaring Fork River appears to alternate between a gaining and losing stream in the vicinity of the Loadout. Ground water measurements taken May 22, 1980 from one monitoring well and two surrounding domestic wells located the water table between elevations 6034 and 6032 near the southeast corner of the site and 6016 near the northwest portion C~ 5-13