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Report of Geotechnical Exploration and Review <br />Fox Street Improvements, Orono, Minnesota AMERICAN <br />July 29, 2016 ENGINEERING <br />Report No. 20-14448 TESTING, INC. <br /> <br /> <br /> <br />Page 10 of 12 <br />year design to range from 1,500 to 2,450, with a Heavy Commercial Average Daily Traffic <br />(HCADT) estimated to range from 88 to 141. <br /> <br />Based on an estimated R-value of 12 for the existing subgrade, the pavement section required to <br />provide adequate support for a 9-ton road design at this traffic level will require a Gravel <br />Equivalent (GE) equal to 20.50 using MnDOT’s “Flexible Pavement Design Using Soil <br />Factors” table. <br /> <br />To provide a GE of 20.50, we recommend the pavement section consist of 5 inches of <br />bituminous (2 inches of bituminous wear, 3 inches of bituminous non-wear) and 10 inches of <br />aggregate base. The total GE of this section is 21.25, which is acceptable. <br /> <br />Based on an estimated R-value of 25 using a 1-foot thick sand subbase, the pavement section <br />required to provide adequate support for a 9-ton road design at estimated future traffic level will <br />require a Gravel Equivalent (GE) equal to 17.50 using MnDOT’s “Flexible Pavement Design <br />Using Soil Factors” table. <br /> <br />To provide a GE of 17.50, we recommend the pavement section consist of 4½ inches of <br />bituminous (2 inches of bituminous wear, 2½ inches of bituminous non-wear), 8 inches of <br />aggregate base, and 12 inches of sand subbase. The total GE of this section is 18.125; the sand <br />subbase was incorporated as part of the composite subgrade and was not used to calculate this <br />total GE. The calculated GE is acceptable. <br /> <br />6.5.1 Bituminous Mix Recommendations and Comments <br />We recommend that the bituminous mixes conform to the latest MnDOT specifications. In our <br />opinion, mixes designated as SPNWB330B for the non-wear course and SPWEA340C for the <br />wear course should be used. We recommend that a full tack coat be applied between lifts (not a <br />tack coat in a ribbon fashion). These mixes should be placed to a compaction specification of a <br />minimum 92% of gmm. Cores should be obtained after compaction to confirm density and <br />thickness. <br /> <br />Even if placed and compacted properly on stable subgrade conditions, bituminous pavements <br />will still experience cracking in 1 to 3 years, primarily due to temperature-related expansion and <br />shrinkage. Each of the designs given above assumes that a regularly scheduled maintenance