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Transit Mix Concrete Co. <br /> stockpile areas, reflecting the bare conditions and assuming a C hydrologic soil type (Schwab, <br /> 2005). This soil type assumes the stockpiles will be constructed with blasted overburden and <br /> have a sandy texture. <br /> Aerial photo interpretation suggests the native lands have forested or grassland vegetation. The <br /> western portion of the site area is predominately forested with a combination of Douglas <br /> Fir/Ponderosa Pine and the eastern portion is generally a community of sagebrush- <br /> grass/mountain mahogany. Based on vegetative and soil type mapping, as well as aerial <br /> photograph review, weighted curve numbers were developed for the various watersheds. The <br /> curve number values were based on tables from TR-55. As there are no values for Fir/Pine <br /> forests representative of the western portion of the site, it was assumed that Oak-Aspen <br /> community would be similar. Based on a D-type soil for the fir/pine forests, a curve number of <br /> 63 was assigned to all undisturbed subwatersheds for the western portion of the site. For the <br /> lower ranch in the eastern portion of the drainage, a weighted curve number of 68 was used <br /> based on the B-, C-, and D-hydrologic soil groups in that portion of the drainage area. For the <br /> portions of the stockpiles and slopes that have been reclaimed, a CN of 71 was selected based <br /> on a meadow with C-type soils. A medium hydrograph response class was designated all the <br /> subwatersheds. A weighted curve number was calculated for subwatersheds that were <br /> comprised of a mix of these cover conditions. Curve numbers are summarized in Table G-4. <br /> Table G-4 <br /> Curve Number Summary <br /> Cover Curve Curve Number Reasoning <br /> Number <br /> Open pit 98 Impermeable bare rock <br /> Overburden, fines, topsoil stockpile 91 Bare cover with C type soil <br /> Reclaimed stockpile and slopes 71 Meadow with C type soil <br /> Sage-grass/Mountain mahogany 68 Weighted by HSG B, C, and D areas <br /> Fir/Pine 63 Forest with D type soil <br /> 5. Sediment Control Structures <br /> Norwest developed a site drainage plan that covers the access road and the site facilities. For <br /> each operational phase and for the re-sloped reclamation phase the site facilities drainage <br /> changes as the Quarry develops and is contemporaneously reclaimed. This section describes <br /> the sediment control structures necessary to meet the water management design criteria for <br /> each of these periods. Figures G-8 through G-12 show the drainage plans for the different <br /> phases of operational periods of the mine, and Figure G-13 shows the drainage plan for the <br /> final re-sloped surface. Each figure includes the network of culverts, road ditches, terrace <br /> ditches, down drain channels, and sediment basins. The entire drainage plan is shown for the <br /> Hitch Rack Ranch Quarry Permit Application <br /> October 3,2017 G-19 <br />