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Peabody Sage Creek Mine — Drainage and Sediment Control Plan <br />2.2.3 Length -Slope Factor <br />Input parameters to determine the length -slope (LS) factor were measured from the drainage <br />and sediment control plan maps. The measurements are included in the SEDCAD4 design <br />demonstrations. <br />2.2.4 Control Factor <br />The control factor (CO is used to account for vegetative or mulch cover. The values utilized <br />are shown in the table below. They were adapted from Renard et al, (1997), as presented in <br />Warner et al, (1998). These values are historical values used for the Seneca II Mine and <br />were agreed upon during discussions between SCC and CDRMS representatives in 1999. <br />TABLE 2.05.3 -E2 -3 <br />Control Factor Values <br />Cover <br />Cover Tye <br />Vegetation <br />C Factor <br />Undisturbed <br />Mixed Brush <br />25% canopy 92 meters tall), <br />80% ground cover <br />0.043 <br />Disturbed <br />Bare Ground <br />None <br />1.0 <br />Reclaimed <br />Herbaceous <br />No canopy, 60% ground cover <br />0.043 <br />2.2.5 Practice Factor <br />The practice factor (P) is used to account for conservation practices for the watershed. <br />SCCC used a practice factor of 1.0 for all conditions. This is a conservative value. <br />2.2.6 Sediment Particle Distribution <br />The sediment particle distribution input into the model was obtained from previous analysis <br />conducted for the Seneca II Mine. <br />3.0 POND DESIGNS <br />This section presents the pond designs and, or as -built plans for Ponds 002, 003, 004, <br />PECOCO and the pre- treatment sumps located at the portal area and within the South <br />Facilities area. All ponds and sumps were designed to treat runoff and the associated <br />sediment load from a 10 -tear, 24 -hour storm event in accordance with Rule 4.05.6 of the <br />Regulations of the Colorado Mined Land Reclamation Board for Coal Mining. Designs <br />prepared for the Peabody Sage Creek Mine utilized the SEDCAD4 model (Schwab, 1998). <br />Historic designs and, or as -built plans for Ponds 003 and 004 used the SEDMOT II model <br />(Wilson et al, 1983). <br />Pond locations and corresponding watersheds are shown on Map 2.05.3 M4. Ponds 002, <br />003, 004 and PECOCO are existing structures that were designed and constructed as part of <br />mining activities at the closed and reclaimed Seneca II Mine. There are no changes to the <br />existing land condition (i.e., extent of disturbance or land use) in the watersheds that drain to <br />Ponds 003 and 004 as a result of the Peabody Sage Creek Mine surface activities. <br />TRO1 -10 2.05.3 -E2.9 12/10 <br />