Laserfiche WebLink
1 <br />SMITH WILLIAMS CONSULTANTS, INC. <br />• <br />brush, or trees and underlain by a loose, rocky sandy soil. The vegetation was viewed <br />as either a thin vegetative stand with limited cover in meadow areas or with good <br />vegetative cover in forested areas. This category also included revegetated ground. <br />Wooded Curve = 66 <br />.Grass Curve = 71 <br />^ Roads and Stockpile Surfaces: SCS Soil Type D (shallow soils with nearly <br />impermeable sub-horizons) was assumed in these areas due to the expected <br />compaction from heavy mining equipment. The area consists of haul roads and <br />horizontal surfaces of ore storage areas. These areas are compacted by haul trucks. <br />Curve = 90 <br />^ Fill Slopes: SCS Soil Type A was used in these areas due to the coarse nature of rock <br />fill material before revegetation. The area consists of segregated coarse rock <br />overburden faces with a very high infiltration rate. Runoff is seldom observed from <br />these areas. <br />• ~ Curve = 50 <br />These curve numbers were used to develop a single composite curve number for each <br />sub-watershed based on areas of land use and soil types. Reclaimed overburden facilities and the - <br />reclaimed Phase 5 VLF were assigned a curve of 71. <br />5.5 Diversion Analysis and Design <br />The storm-water diversion channels for the VLF referenced in this design package are shown on <br />Drawings A510 and A520. The diversion structures are primarily trapezoidal diversion channels <br />that are located around the perimeter of the VLF. Roadside diversion channels are also included <br />in areas with low peak flows and/or small watersheds. In addition, where needed, diversion <br />channels along roadsides and elsewhere will collect storm water flows and direct runoff to the <br />trapezoidal diversion channels. All trapezoidal and roadside diversion channels were sized to <br />convey the 100-year/24-hour peak flows. _ <br />As noted previously, Phase 5 VLF will likely be constructed over a period of 3 to 4 construction <br />seasons. During staged construction, temporary diversions will need to be constructed to route <br />surface wafer around the VLF until the ultimate footprint and diversions are constructed. <br />S:\PROJECTS\1125 CC&V PHASE 5 VLF\H2 - DESIGMAREQUA VLF\VLF PHASE 5 FINAL REPORT V2.DOC 39 <br />