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Riverstone SouthEAWDraft December 2020 <br />b.Soils and topography-Describe the soils on the site, giving NRCS (SCS) classifications and descriptions, <br />including limitations of soils. Describe topography, any special site conditions relating to erosion <br />potential, soil stability or other soils limitations, such as steep slopes, highly permeable soils. Provide <br />estimated volume and acreage of soil excavation and/or grading. Discuss impacts from project activities <br />(distinguish between construction and operational activities) related to soils and topography. Identify <br />measures during and after project construction to address soil limitations including stabilization, soil <br />corrections or other measures. Erosion/sedimentation control related to stormwater runoff should be <br />addressed in response to Item 11.b.ii. <br />TheWeb SoilSurvey indicates the project areaincludes sevensoil mapping units that consistof <br />mostly loamy sands(Table 4andFigure 7). <br />Table 4. Soil Classifications <br />% of % <br />SymbolSoil NameHydric CategoryFarmland Category <br />AreaHydric <br />Predominantly <br />BaBecker very fine sandy loam9.57Prime farmland <br />non-hydric <br />Predominantly <br />D67AHubbard loamy sand, 0-2% slopes20.01Not prime farmland <br />non-hydric <br />Predominantly <br />D67BHubbard loamy sand, 1-6% slopes16.03Not prime farmland <br />non-hydric <br />Hubbard loamy sand, 2-12% <br />D67C2.80Non-hydricNot prime farmland <br />slopes <br />Farmland of statewide <br />DnADickman sandy loam, 0-2% slopes37.60Non-hydric <br />importance <br />Farmland of statewide <br />DnBDickman sandy loam, 2-6% slopes12.50Non-hydric <br />importance <br />Nymore loamy coarse sand, 12- <br />NrD1.70Non-hydricNot prime farmland <br />25% slopes <br />Five of the seven soils do not have limitations for dwelling units and local streets. Two of the soils <br />(Ba and NrD) have limitationsdue to factors such as flooding, depth to saturated zone,frost action, <br />and slope. Soils in the project area are generally considered slightly to moderately susceptible to the <br />sheet and rill erosion by water, as indicated byslopes andK factors that range between 0.02and <br />0.37. <br />Grading operations for residential development construction are expected to affect about 68.0acres <br />and involve movement of about 350,000cubic yards of soilto construct streets, residential building <br />pads, and stormwater features. Grading is expected to avoid disturbanceof trees that will be <br />preserved, which cover about 7.73acres. <br />Elevations in the project area range from 880feet above mean sea level at the highest point in the <br />northwesternpart of the site to 858 feet at the lowest point in the southeastern part of the site. <br />Review of two-foot contour mapping indicates the northwestern part of the site includes about one <br />acre of 12-14% slopesand the site does not include any bluffs(Figure 5). Soilsmapping classifies <br />thesteepestpart of the site, about 1.33 acre, as 12-25%slopes (Table 4,Figure 7). As shown on the <br />9 <br /> <br />