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somewhat mandated due to a combination of array size restrictions, minimum internal convolution <br />interval, and the user specified time increment for saving convoluted values. <br />Drainage Basin Area <br />The watershed boundaries for the reclaimed mine area watersheds were determined by direct <br />measurement from a 1" = 500' scale computer-generated map. <br />The watershed delineation is shown on Figure 1, Pond HG-8 Watershed. <br />Time of Concentration, T~ <br />The time of concentration was calculated using the SCS upland method (a utility of SEDCAD). All <br />hydraulic lengths, drainage heights and slopes were measured directly from the 1" = 500' scale <br />computer-generated map. The calculated T~ values for each watershed are also shown on the <br />SEDCAD printouts. <br />Muskingum Routing Parameters, K, X <br />The Muskingum Routing Parameters were calculated using the SCS upland method. All hydraulic <br />lengths, drainage heights and slopes were measured directly from the 1" = 500' scale computer- <br />generated map. Values for hydraulic lengths, drainage heights, and slope are summarized in the <br />SEDCAD printouts. <br />Curve Number, CN <br />The SCS Curve Number (CN) designates the runoff potential of an area. A CN was determined for <br />the revegetated watershed based on the hydrologic soil type, as well as the hydrologic soil cover <br />complex, and the range cover condition rating. The CN for the contributing drainage area for Pond <br />HG-8 was determined using the soil mapping of the area, the watershed vegetation condition, and the <br />following assumptions: <br />• Soil mapping of the pre-mining conditions (HGCC, 1980) identified two primary <br />soils in the reclained drainage area of Pond HG-8: l) the Routt Loam, a type C <br />hydrologic soil group; and, 2) the Skylick Loam, a type B hydrologic soil group. <br />In addition, there were several minor soils which were dominately a type B <br />hydrologic soil group. Subsequent soils mapping provided by the Steamboat <br />Spring, Colorado office of the National Resources Conservation Service (MRCS), <br />formally the SCS, reclassified the Skylick soil as a Foidel soil, classified a <br />previously un-named sandy loam as a Claybum soil, and modified the boundaries <br />of the soil map units. Hydrologic soil group information was obtained from the <br />NRCS (Vance Fulton, NRCS soil scientist, personnel communication, 1996). The <br />Routt Loam was the dominant pre-mining soil type, comprising 54~ of the soil in <br />the area. The Foidel and Claybum soils made up approximately 30% of the pre- <br />mising soil, while the remaining 1630 of the area was comprised of the other minor <br />c:~87Thg8~prirtury'vne7had.how 7/16/96 <br />3 <br />