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<br /> <br />Portal #1 Reclamation Channel <br />page 2 - <br />The Soil Conservation Service runoff curve number procedure (SCS, <br />1980) was used to calculate the volume and peak rates of runoff. <br />The runoff curve number for the undisturbed areas above the <br />reclaimed area was determined to be 67. Refer to the current <br />hydrologic calculations included in Appendix A for further <br />information. Appendix B is a copy of the relevant permitting <br />hydrology that was developed in 1985 and is pertinent to the <br />reclamation channel design. Table 1 summarizes the calculated <br />flows in the vicinity of Portal #1. <br />Table 1. Desiqn Discharges Around Reclaimed Portal #1 <br />Portal #1 10-yr. event 25-yr. event <br />Precipitation, in. 1.6 2.0 <br />Direct Runoff, in. .07 .17 <br />Volume of Runoff, ac.ft. .12 .28 <br />Peak Discharge, cfs 2.1 5.1 <br />Even though the hillside is steep in the vicinity of the <br />reclaimed portal, the undisturbed nature of the upper area and <br />the small contributing area (20 acres) results in low rates of <br />runoff. <br />~i <br />Water 6 Environmental Systems Technology, Inc. April, 1994 <br />