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~~ <br />i <br />• <br /> <br />RSS Operational Drainage to Pond 8 <br />Calculation Rational and Results Summary <br />Rational: <br />- Calculated using Sedcad+ Ver. 3 Modified by technical revision -include the guazd <br />shack concrete ditch and drainage pipe. <br />- The Vpan concrete ditch, and 12"PVC drain pipe replaces the grated channel trapezoidal <br />ditch and culvert to Pond 8. <br />- The Pond 8 hydrologic calculations that determine the capacity of Pond 8 on pages RSS- <br />9and ] 0 remain unchanged as the runoff to Pond 8 is unaffected by the change in <br />structures. <br />- The non-pond structure input and output table on pages RSS-] 1-13, have been revised to <br />indicate which structures have been removed. <br />- Areas, slopes and flow paths digitized from 100 scale topo maps flown in 11/94. The <br />attached 400 scale diagram represents the subwatersheds digitized. <br />- The soil map, Exhibit 23, shows the azea as Area 80 -"Stony Land" and Area 52C <br />"Utaline Stoney Loam. There is no defined soil group associated with the "stony land" <br />soil therefore Table 5.1 in the Sedcad reference manual was used to determine a soil <br />group. Generally the soil samples for this and other disturbance areas classifies the soil <br />to be sandy to silty loam (Tab Section 9) which equates to a "B" soil group. Utaline has a <br />published soil group of "B" in Table B-1 of Peak Flows in Colorado. A "D" soil group <br />was used for operations azeas where clays from the mining operations may be <br />incorporated in the surface. The following CN's were used in the calculations: <br />64 - B soil group, sage-grass with 20% cover. <br />77 -Estimated between 64 and 86 for a partially disturbed hillside <br />86 - B soil group, fallow, bare soil. Used for topsoil piles, ponds and dirt <br />slopes. <br />92 - D soil group, gravel road. Used for parking, storage and stockpile areas. <br />95 -Estimated between 92 and 98 for portal azea <br />98 -Concrete and pavement <br />• <br />- 10 year 24 hour storm event of 1.4" <br />Results Summary: (other information may have been generated in this section but is not being <br />used in the site drainage design at this time.) <br />Structure # Structure Description <br />Design <br />I 1 1 Collection ditch along <br />access road 2:1 side slopes, 7% grade, .7' min. depth <br />RSS-6 <br />(Rev. 9/10/98) <br />