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,~-- <br />E <br />ctober l7, 1996 <br />Ms. E. Cosby <br />Page 5 <br />TABLE4 <br />PRACTICE FACTOR <br />Surface Practice Practice Factor <br />Disturbed -Roads and Facility Area None 1.0 <br />Newly Disturbed Reclaimed Moderak 0.65 <br />1 to 2 Year Reclamation Moderate 0.65 <br />3+ Year Reclamation Moderak 0.65 <br />Undisturbed None 1.0 <br />3.0 12ESi1I.TS <br />Table 5 presents the results of the SEDCAD+ analyses for the Gulch A Pond under each condition. According <br />to the analyses, the amount of sediment produced from the post-mine condition is less than that produced from <br />the existing conditions. This can be explained by the detention time in the routing pazameters from the dis[wbed <br />areas. As anticipated, the volume of discharge is much larger from the post-mine condition than the existing <br />condition. <br />TABLES <br />SEDIMENT POND DATA SUMMARY <br /> Cinch A Pond Culch A Pood <br /> (Existing Condition) (Pmt-Mine Conditions) <br />Watershed Area (acres): <br />Disturbed Area 28.2 60.3 <br />I to 2 Year Reclamation 55.4 28.2 <br />3+ year Reclamation 203.0 581.2 <br />Undisturbed 64.2 60.3 <br />Total 350.8 730.0 <br />10-Year, 24-Hour Storm Event (inches) 1.8 1.8 <br />RunoR-Volume (acrc-feet) 1.94 3.93 <br />3 Year Sediment Yield (acre-feet) 4.1 I 2.37 <br />Pond Elevations (R): <br />Principal Spillway Invert (>6] 8.3 6617.9 <br />Emergency Spillway Invert 6620.0 6620.0 <br />Top oCErnbanl;mertt 6622.4 6622.4 <br />Pond Storage Volumt (acre-feel): <br />Below Principal Spillway 6.51 6.19 <br />Below Emer enc S illwa 7.96 7.96 <br />