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October 7, 2024 <br />ITT Project 24-327 <br />Various Gravel Roads <br />IP 25-07 <br />Ramsey, Minnesota <br />E. Pavement Recommendations <br />Areas A & B: <br />For the portion of Xenolith Street NW that runs through the wetland area, we recommend using a <br />geogrid in the aggregate base to provide support for the pavement. We recommend placing a <br />multi -axial geogrid withing the aggregate base layer. We recommend 6 inches of aggregate be <br />placed above the geogrid and at least 2 inches of aggregate remain under the geo rid. The <br />existing aggregate could be salvaged from the roadway to be re -used above the geogrid. With the <br />geogrid reinforced aggregate base and granular material over the organic silt and peat, we <br />recommend 3.5 inches of bituminous be placed over the aggregate. <br />The clayey sands (SC), silty clayey sands (SC-SM) and silty sands (SM) encountered on sites A <br />and B are classified as A-2-4 and A-2-6 soils in accordance with the American Association of <br />State Highway Transportation Officials (AASHTO) classification system. A-2-4 and A-2-6 soils <br />are rated as fair material for use as roadway subgrade material. Without benefit of a laboratory <br />R-value determination and based on Mn/Dot guidelines, we recommend an R-value of 30 be <br />assumed for the onsite soils. <br />Based on an assumed R-value of 30, we recommend the following bituminous pavement section <br />for low volume, 9-ton, residential streets: <br />Thickness Course/Description G.E. <br />3.5" MnDOT Superpave Bituminous 7.9" <br />8.0" MnDOT 3138 Class 5 Aggregate Base 8.0" <br />11.5" TOTAL 15.9" <br />In using the assumed R-value for bituminous pavement or concrete design, it is essential that the <br />subgrade be constructed of uniform soils at a moisture content and density in accordance with <br />MnDOT specification 2105 and capable of passing a test roll in accordance with MnDOT <br />specification 2111. The native, undisturbed soils may need preparation (drying and compacting) <br />to pass a proof roll. If the subgrade is not compacted, uniform and capable of passing a test roll, <br />then we recommend the subgrade be scarified and recompacted or subcut and replaced with <br />Page 9 <br />