4.4 EAW Attachment - Laserfiche WebLink

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12 Pavement Section Based on an estimated R-value of 50 and a maximum of 150,000 ESAL’s we recommend a pavement section consisting of a minimum of 3 ½ inches of bituminous (1 ½ inches of wear course and 2 inches of base course) underlain by a minimum of 6 inches of aggregate base. If a heavy-duty section is required, we recommend a 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. 4.12 Materials and Compaction We recommend specifying aggregate base meeting MN/DOT Class 5 aggregate base. We recommend the aggregate base be compacted to 100 percent of its maximum standard Proctor. We recommend that the bituminous wear and base courses meet the requirements of MN/DOT specification 2360. We recommend the bituminous pavements be compacted to at least 92 percent of the maximum theoretical density. We recommend specifying concrete that has a minimum 28-day compressive strength of 4,500 psi, and a modulus of rupture of at least 600 psi. We recommend Type I cement meeting the requirements of ASTM C150. We recommend specifying 5 to 7 percent entrained air for exposed concrete to provide resistance to freeze-thaw deterioration. We also recommend using a water/cement ratio of 0.45 or less for concrete exposed to deicers. 4.13 Stormwater Ponds/Infiltration Basins Based on the provided concept plan, the project will include constructing several storm water ponds/infiltration basins on the project site. We were no provided any information regarding proposed bottom elevations for the ponds. Below the topsoil the soil borings encountered poorly graded sand, poorly graded sand with silt and silty sand corresponding to the ASTM classifications of SP, SP-SM and SM. For stormwater pond/infiltration basin design it is our opinion that the infiltration rates presented in Table 5 can be used for pond design. These values were obtained from tables included in the “Minnesota Storm Water Manual.” Table 5. Design Infiltration Rates In-situ Soils Soil Description Hydrologic Soil Group Design Infiltration Rate (in/hr.) SP Poorly Graded Sand A 0.8 SP-SM Poorly Graded Sand with Silt A 0.8 SM Silty Sand B 0.45 Field tests (double ring infiltrometer) can be performed within the proposed infiltration basin area to verify infiltration rates of the in-situ soils. We would be pleased to provide these services if required or requested.