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aALLIANT ENVIRONMENTAL ASSESSMENT WORKSHEET 11 Robinson Sod Farm <br />10. Geology, Soils and Topography/Land Forms <br />a. Geology - Describe the geology underlying the project area and identify and map any susceptible <br />geologic features such as sinkholes, shallow limestone formations, unconfined/shallow aquifers, or <br />karst conditions. Discuss any limitations of these features for the project and any effects the project <br />could have on these features. Identify any project designs or mitigation measures to address effects to <br />geologic features. <br />The bedrock geology of the site primarily consists of Jordan Sandstone and the St. Lawrence <br />Formation. Depth to bedrock is between 150' and 200' for the majority of the site, with an area <br />between 100'-150' in the northeast part of the site and an area between 200' and 250' on the south <br />edge of the site (Mossler, 2013). The surficial geology of the site consists of muck/peat in the west <br />and sand facies in the east (Meyer, 2013). <br />There are no known geologic hazards, karst, sinkholes, or other conditions that would require <br />mitigation measures on the property (Berg, 2016). <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 <br />activities (distinguish between construction and operational activities) related to soils and topography. <br />Identify measures during and after project construction to address soil limitations including <br />stabilization, soil corrections or other measures. Erosion/sedimentation control related to stormwater <br />runoff should be addressed in response to Item 11.b.ii. <br />The USDA NRCS Web Soil Survey indicates that the project site includes 5 soil mapping units that <br />consist mostly of muck and peat that are hydric soils (Appendix A, Figure 8; Table 5.). The soils are <br />very limited for dwellings without basements, single family dwelling units, and local roads that <br />include factors such as ponding, frost action, and subsidence. The Web Soil Survey indicates that <br />organic soils are not as susceptible to rill and sheet erosion as mineral soils. The sandy soils of the <br />area have a relatively low erodibility with K-factors ranging from 0.1 to 0.24. <br />The grading operations during construction is expected to impact approximately 155 acres and <br />require large volumes of soil corrections. Grading will include approximately 600,000 cubic yards of <br />soil. The grading will involve the movement of soil to construct new roads, building residential pads, <br />and stormwater features. <br />Table 6. Soil Classifications on the Project Site <br />Rf Rifle mucky peat 48.3% 100 Hydric Not prime farmland <br />Markey muck, <br />Ma occasionally ponded, 32.3% 100 Hydric Not prime farmland <br />0 to 1 percent slopes <br />Iw Isanti fine sandv loam 12.9% 93 Hvdric Not prime farmland <br />PAGE 9 <br />