Agenda - Public Works Committee - 01/21/2025

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October 7, 2024 ITT Project 24-327 Various Gravel Roads IP 25-07 Ramsey, Minnesota geotextile fabric and select granular material meeting MnDOT specification 3149. The top of the subgrade should be compacted to a minimum of 100% of standard proctor maximum density. The subgrade should be sloped towards the edges to provide drainage. Areas C through F: The silty sand (SM), poorly graded sand with silt (SP-SM) and poorly graded sand (SP) outwash soils on site this site are classified as A-1-b and A-3 soils in accordance with the American Association of State Highway Transportation Officials (AASHTO) classification system. A-1-b and A-3 soils are rated as excellent material for use as roadway subgrade material. Without benefit of a laboratory R-value determination and based on Mn/Dot guidelines, we recommend an R-value of 70 be assumed for the onsite soils. Based on an assumed R-value of 70, we recommend the following bituminous pavement section for low volume, 9-ton, residential streets: Thickness Course/Description G.E. 3.5" MnDOT Superpave Bituminous 7.9" 6.0" MnDOT 3138 Class 5 Aggregate Base 6.0" 9.5" TOTAL 13.9" In using the above R-value for bituminous pavement design, it is essential that the subgrade be constructed of uniform soils at a moisture content and density in accordance with Mn Dot specification 2105 and capable of passing a test roll in accordance with Mn Dot specification 2111. The native, undisturbed soils may need preparation (drying and compacting) to pass a proof roll. If the subgrade is not compacted, uniform and capable of passing a test roll, then we recommend the subgrade be scarified and recompacted or subcut and geotextile fabric placed along with select granular material meeting Mn Dot specification 3149. The top of subgrade should be compacted to a minimum of 100% of standard proctor maximum density. The subgrade should be sloped towards the edges to provide drainage. Page 10