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III IIIIIIIIIIIIIIII ~~G ~~~- ~,~/o, <br />999 S~C (f ~,^M~L ~~ ~xo~Pr~us ~, <br />November 1993 Raton Creek * Small Arco Exemption • 1 <br />• SMALL AREA EXEMPTIONS <br />LOADOUT AREAS <br />1.0 SANTA FE LOADOUT AREAS <br />Recently both Santa Fe lease areas have been reclaimed consistent with the approved reclamation <br />plan. During reclamation both sites were regraded to effettively control run-off. Given the new <br />site configurations, EFMC has competed hydrologic designs to control surface water runoff from <br />the newly regraded lease areas. <br />Lease Area 1 includes approximately 1.3 acres of disturbed regraded area. The area is graded so <br />that run-off is diverted to the center of the site and then northeast to an existing box culvert as <br />shown on SF Loadout Sites Map, (Map 23). To control runoff from the site EFMC will <br />cons[rutt a sediment fence at the northeast end of the site as shown on the SF Loadout Sites <br />Map, (Map 23). The sediment fence will be adequately sized to safely pass the peak discharge <br />from a 10-year 24 hour event. Run-on to the site is effectively controlled by the surrounding <br />railway tracks and associated ballast road-bed. <br />Lease Area 2 includes approximately 2.2 acres of regraded area surfaced with gravel. The area <br />has been regraded so that all runoff is diretted to the south. Run-off from the site will be <br />controlled by a collettion ditch and berm which will divert all run-off to a sediment fence <br />located at the south corner of the site as shown on the SF Loadout Sites Map, (Map 23). Run- <br />• on to the site is effettively controlled by the existing railway [racks and associated ballast road- <br />bed and one berm constructed along the northeast edge of [he truck turnaround area as shown <br />on the SF Loadout Sites Map, (Map 23). All drainage structures will be constructed to safely pass <br />[he peak discharge from a 10-year, 24hour event. <br />1.1 Hydrology Designs <br />Runoff peak discharge calcttla[ions were performed utilizing the SEDCAD+ computer model <br />consistent with the methodology previously discussed in this Exhibi[. The sediment fence and <br />diversion ditch and berm were designed to handle the peak discharge from a 1C-year, 24-hour <br />storm event. <br />1.2 Hydrology Inputs <br />All hydrology inputs are shown on [he SEDCAD+ computer printouts (see attached). <br />The CN numbers used for both areas were obtained from Procedures for Determining <br />Peak Flows in Colorado and Technical Release No. 55 (USDA-SCS, 1980). Based on soil <br />type and vegetation cover, curve numbers were determined using Table 2-2a and 2-2d, <br />USDA-SCS TR-55, for the following conditions: <br />Disturbed <br />Soil Type: B <br />Ground Cover: NA <br />Cover Type: Dirt Road <br />CN: 82 <br />n:~esbarxoz.res <br />i vzvez io,m TerraMat>iz/ACZ lnr. "P.O. Box 774018 * Steamboat Spnngs, Colorado 80477 "(303f 879-6?60 <br />