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The maximum allowable velocity of water in the vegetated interceptor ditch is 5.000 fps. A ditch design <br />analvsis is at Enclosure 6. <br />During construction, the erodible fraction of the soil matrix is expected to be rapidly removed, leaving a <br />protective armor (ditch lining) of cobble sized materials in [he circumvential ditches. Thus the circumvential <br />ditch material is desmbed as 'graded silts -cobbles colloidal'. The maximum allowable velocity of such a <br />pro[ective ditch lining is 5.50 fps. Ditch desigtu are at EnGosures 7 and & <br />6. LIMITATIONS OF THE SEDCAD+ MODEL AND <br />SUBSTITUTIONS <br />SEDCAD+ does no[ model silt fences or straw bales. No con[ribution to sedimen[ control or mitigation of <br />af[ecu on water quality was made in this analysis. <br />SEDCAD+ does no[ model [ores[ (brush) litter as a filter. The litter was equaled [o a grass filler. Equivaien[ <br />grass filter inpu[ parameters used were: <br />1) a slope of 20cJo. <br />2) a Manning "n' value of 0.1 (a very dense grass). <br />3) a spacing of 0.2 inches (between grass stems). <br />4) a height of 2 inches. <br />5) a filter width of 390 feet (the lower perimeter of the pile). <br />6) an infiltration rate of 0.1. <br />'>) a stiffness factor of 20. <br />8) a length of 30 feet. <br />7. SEDCAD+ ANALYSIS INFORMATION <br />The Small Area Exemption SEDCAD+ demonstrations are summarized in the following tables. <br />(War EIl• S.iE Lone Pine Gulch Developmrnt Waste Pilq Page 6 of S) <br />