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Sunwood Drive—Street Improvements <br /> .4jo Ramsey,Minnesota <br /> `.Oe NTI Project No.16.61770.100 <br /> If imported fill is required in paved areas it should consist of debris free, non-organic, mineral soil similar <br /> in composition to the subgrade soils encountered in the surrounding areas. If sand is imported into <br /> areas that are underlain by relatively impervious fine grained soils the sand layer must be drained with <br /> drain tile in order to prevent frost heave from water trapped within the imported sand layer during <br /> freezing temperatures. Individual lifts of engineered fill should be tempered for moisture content, <br /> placed and compacted as noted in the "Placement and Compaction of Engineered Fill" section in <br /> Appendix B of this report. <br /> The performance of stabilometer or similar tests, were beyond the scope of this report; however,they <br /> may be performed, upon request,for an additional fee. Based on the encountered soil conditions, we <br /> estimate that a properly prepared poorly graded sand with silt (SP-SM) soils will have an average <br /> stabilometer R-Value of 40. <br /> For a 20-year design pavement life, Table 3 presents our thickness recommendations for flexible <br /> (bituminous) pavement. These recommendations were based upon the encountered subgrade <br /> conditions, estimated R-value for the existing subgrade soils, the assumed AADT volumes, and the City <br /> of Ramsey's typical pavement section for the respective project area. <br /> Table 3: Flexible Pavement Thickness Design' <br /> Sunwood Drive <br /> Calculated Required City's Typical <br /> Pavement Section Pavement Section Pavement Section <br /> Bituminous Wear Course(inches) 1.5 1.5 <br /> Bituminous Base Course(inches) 2.0 2.0 <br /> Class 5 or 7 Aggregate Base(inches) 6.0 4.0 <br /> 1. Assumed AADT volume of 3500 and an estimated R-value of 40. <br /> 2. The calculated required section was greater than the City's typical section for residential streets,thus NTI <br /> recommends that the Calculated Required Pavement Section be implemented. <br /> Pavement recommendations assume the subgrade soils and aggregate section below paved surfaces will <br /> drain to subsurface piping for eventual discharge into storm sewer, or above grade to ditching, or similar <br /> acceptable systems. Lack of surface and subsurface drainage will significantly reduce the capacity and <br /> longevity of the pavement systems indicated above. <br /> We recommend pavements receive annual maintenance, as a minimum,to correct damages to the <br /> pavement structure, clean and infill cracks which develop, and repair or resurface areas which exhibit <br /> reduced subgrade performance. The lack of maintenance can lead to moisture infiltration of the <br /> pavement structure and softening of the subgrade soils. This, in turn, can degrade the performance of <br /> the pavement system and result in poorly performing pavements with shortened life expectancy. <br /> Page 6 of 7 <br />