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nla7 1999 C>Ona Twurq~mi(r * Pmrd D EraGmrion 1 5 • TABLE 1.4 PRACTICE FACTOR Surface Surface Tv a Practice Practice Factor Reclaimed Regraded Reclaimed Furrow 0.5 Spoils (Pre-Law) Spoils, Paztial Grading Rough and Irregular 0.8 Refuse Coarse Dlaterial Terraced 0.8 Disturbed Stripped None 1.0 3.6 Sediment Particle Distribution A sediment particle size distribution \vas input into the SEDC~ID ~1 computer model. The distribution was obtained from previous anal7ses performed Eor the TCC [nine and is shown on the SEDCAD 4 printouts. 4.0 POND D SUMMARY T1te modeling of Pond D shows that it gill effectively treat the runoff produced from the 10-}'ear, 2d- hour storm event plus the continuous inflow due ro mine water pumping and springs. The input parameters and results are shown on die SEDC~ID 3 printouts and summarized in Table 15, Pond D Summary. • The stage/storage relationship used for Pond D was provided b\• the Epps sun~e}' conducted in 1996. The location of Pond D and its corresponding subwatersheds are shown on Ivlap 9,1, H}drologic Features and Sediment control. .•1 simplistic approach was taken in identift'ing disturbed and undisturbed azeas contributing runoff to each pond. The following areas were segregated as subwatersheds: • Reclaimed (3 areas) • Pre-Law Reclauned • Refuse Pile • Disturbed - Ttfiring • Dtsurbed -Facilities • Pond D Pond D has a principal and emergent}' spillrva}'. .js-built information for the nvo spillways was obtained from the Epps sun'et' conducted in 1996 and other required information was obtained from TCC personnel. T'he principal spillway consists of a G.G Feet tall cmp riser and an accompanying cmp outlet. The riser is '_ feet in diameter and the outlet is 1.5 feet in diameter. The riser is perforated at nvo elevations (G8~7.10 and G8~1920) with four 4-tnch holes. Dfodebng shows that the principal spillway will safely pass the peak flow From the 10-tear, 24-hour storm event, without discharging from the emergent}' spillway. The emergent}' spillways consist of a 90-foo[ wide aapezotdal channel with 3H: 1V side slopes. . hfodeGng of Pond D for the 25-tear, 2~1-hour storm event shows that the entire peak Flow will pass [hrough the rinci al s illvv without discharging through the emergency spillway. This is t}'pical of some older ponds chat were designed Eoc much larger storm events. As a result the minimum freeboard experienced during the 25-\~ear, 24-hour storm is 2.i feet. A summan' of Pond D is presented on Alan rgomer}~ \f%aaon ~Lnmg G roue ' 165 ~. Cmon boulevard, ~uirr ~ 10 ' Lakeunod, f obrado 811228 ' (3031 763-5 NO D-9