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<br />and then the weighted CN for the 25 sub-basins. Minimum infiltration <br />rates for the various sub-basins were then developed based upon the <br />undulation of the land and the S.C.S. field data accumulated during <br />and subsequent to the soil survey. The results and reliability of this <br />approach has been reviewed with the S.C.S. engineering staff at Sterling. <br />The numerous depressions existing throughout the basin have a <br />strong influence on the surface runoff parameters and further represent <br />a significant benefit for the groundwater recharge in the region. The <br />aspect of interest for this study is the surface runoff parameters. <br />The excess precipitation from major storms (those storms generating <br />more rainfall than the soil will accept by infiltration) will surface <br />flow into these closed depressions and the water will pond until deep <br />infiltration and evaporation exhaust the surface storage. Most of the <br />larger depressions have been field checked to insure the potential <br />storage capacity exceeds any potential runoff from storms up to a 100 <br />year recurrence interval. The density and size of some of the larger <br />depressions can be noted on Figure 2. <br />In addition to the numerous depressions throughout the basin, the <br />railroad embankment represents a major physical feature that creates an <br />influence on the storm runoff through the major drainageway. U. S. Highway <br />34 also transects the basin but does not affect the storm runoff as <br />significantly as the railroad embankment. The railroad embankment crosses <br />the drainageway at four main locations (other sub-basins also are transected <br />by the railroad). The upper or westernmost is located approximately 7000 <br />feet west of Hyde. Two cast iron culverts (one 26 inch diameter, the other <br />30 inch diameter)' are available to carry flow northward under the seven <br /> <br />-4- <br />