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Nnrrmhrr l?47 CPCC -.1'rr6nrdrn )"rc•ld Danuur..rrulion - Aline 3 • 7 <br />~. •..• ~ <br />fhc weighted average I< (actor for Block North is 0.30 and for Block South is 028. K factor calculations for <br />• the reclaimed areas can be lound in Appendix A, Table 2. K facrors for the reference areas are similar to [hose <br />of the disturbed areas \vith a K value for the Cropland of 0.24, Low Sage of 0.32, and Pastureland of 0.32. K <br />values for the three reference areas were averaged a~ for the Combined Reference Area. The soils found in <br />Blocks North and South are similar to the soils found in adjacent pastw'eland areas; therefore. the K factors for <br />the recla1imed blo11cIks~ should not vary' significantly when compaared to K factors for adjacent unmined areas. <br />r~• { -F~+^~[- ~ .W-~ = acf ec..~_ ~{ p c.c.t~ v''-~ . ~ y fa.c . <br />Representative Slupe Length. The slope length is representative of the typical slope length over the <br />subwatershed and was determined as the distance from point of origin of overland flow to the point where [he <br />slope decreases such that significant deposition occurs or until Flow enters a defined channel. For the <br />representative one acre parcels evaluated in this model, the assumption was made [ha[ overland Flow typically <br />occurs over the entire length of the modeled area (208.71 feet) for [he unmined parcels. For the mined parcels, <br />overland flow is interrupted by [he presence of contour furrows which were established during the final grading <br />of the recl::i:ned parcels. To simplify the model inputs, the conrour furrows- were modeled to occur at 52.17 <br />foot width increments. A review of aerial photos covering [he proposed bond release blocks and an on the <br />ground inspection of these areas in the field indicates that furrows are typically established at behveen 40 and <br />50 feet in [Ite areas with Flatter slopes and between 20 and 30 feet in areas with steeper slopes. The <br />representative slope length is therefore conservatively overestimated on the reclaimed sites in the SEDCAD+ <br />model evaluations. The principle of contour furrowing as applied at CYCC was to increase depression storage <br />and interrupt overland Flow to the extent that design event runoff from the drainage area could be completely <br />contained in surface depressions. <br />Average Slope. The average slopes are entered in percent and are the typical or representative slopes for <br />overland flow for each block. These average slopes were measured directly from the 1" = 500' scale maps <br />• available for bout areas. As previously mentioned, these representative slopes were utilized ilt tnodelittg runoff <br />responses for both the mined and unmined areas. <br />Control Practice Factor. The control practice (CP) factor is defined as the ratio of sediment loss from an area <br />with a given cover and conservation practice to that of a field in continuous fallow. CP factors as determined in <br />this evaluation are dependent upon [he percentage of vegetative ground cover in contact with the ground <br />surface. These percentages were estimated as the sum of 25% of the average vegetative cover (both desirable <br />and undesirable species) plus the average litter cover as determined by the collected data from the 1995, 1996, <br />and 1997 vegetative surveys conducted by CYCC for the areas being evaluated. To account for the increased <br />surface t'ouglntess associated with the establishment of contour furrows and typical seedbed preparation <br />practices utilized such as ripping or chisel-plowing, the table-value CP factors for the reclaimed areas are <br />adjusted to accoultt for surface roughness. As shown at the bottom of Table S.A.2, found in Applied Hvdrolo¢y <br />and SedimentoloQV for Disturbed Areas; Barfield, et al. (1981), the following multipliers are used to account for <br />increased surface roughness on reclaimed lands: <br />Very Rough .40 ~~~ <br />Moderate .65 - ~-~'^"' <br />Minor .90 <br />Given the seedbed preparation methods used in reclamation at these sites, existing surface roughness for Blocks <br />North and South falls behveen very rough and moderate; therefore, a multiplier of 0.50 was used to determine <br />model inputs. The model input CP factors were determined using Table S.A.3 - "C Factors for Permanent <br />Pastore, Raltgeland, Idle Land, and Grazed Woodland"; Barfield, et al. (1981), page 392: <br />• <br />is\b°ndre l\nu nc 3\xd\scd m i ncAdoc <br />