Agenda - Council - 09/14/2021 - Laserfiche WebLink

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R-Value R-Value testing was beyond the scope of this project. The soil borings predominantly encountered sand soils meeting the ASTM Classification SP or SP-SM. Soils meeting the ASTM Classification CL typically have R-Values ranging from about 50 to 75. It is our opinion an R-Value of 50 can be used for pavement design. Pavement Section -Roadways Based on an estimated R-value of 50 and a maximum of 75,000 ESAL's we recommend pavement section consisting of a minimum of 4 inches of bituminous (2 inches of wear course and 2 inches of base course) underlain by a minimum of 6 inches of aggregate base. 4.11 Pavement Materials We recommend aggregate base meeting MN/DOT specification 3138 for Class 5 aggregate base. We recommend the aggregate base be compacted to 100 percent of its maximum standard Proctor dry density. We recommend that the bituminous wear and base courses meet the requirement of MN/DOT specification 2360. We recommend the bituminous pavements be compacted to at least 92% of the maximum theoretical density. We assume the streets/roadways will include concrete curb and gutter. We recommend specifying concrete that has a minimum 28-day compressive strength of 4,000 psi. We recommend specifying 5 to 8 percent entrained air for exposed concrete to provide resistance to freeze -thaw deterioration. We recommend slump, air content and compressive strength test of Portland cement concrete. 4.12 Stormwater Ponds & Infiltration Basins We anticipate that stormwater ponds will be constructed as part of the project. We were not provided any information regarding pond bottom elevations. For the purposes of this evaluation, we've assumed the bottoms of the pond would be set about 5 feet below existing site grades. At the anticipated pond bottom elevations, the soil boring encountered sand soils generally meeting the ASTM Classification SP or SP-SM. Lesser amounts of silty clay (CL- ML) and clayey sand (SC) were also encountered in the boring and infiltration rates for these soils are also presented below. It is our opinion that the infiltration rates presented in Table 6, which were obtained from the "Minnesota Storm Water Manual", can be used for stormwater pond design. Table 6. Infiltration Rates In -situ soils Soil Description Hydrologic Soil Group Design Infiltration Rate (in/hr) SP & SP-SM Poorly Graded Sand & Poorly Graded Sand with Silt A 0.8 SC Clayey Sand D 0.06 CL-ML Sandy Lean Clay and Lean Clay D 0.06 12