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Table 5: Harrow Avenue - Recommended Flexible Pavement Section Section Thickness (inches) Bituminous Wear Course, MnDOT 2360 3 MnDOT Class 5 Aggregate Base - Reclaim 8 Within several years after initial paving, some thermal shrinkage cracks will develop. We recommend routine maintenance be performed to improve pavement performance and increase pavement life. Pavement should be sealed with a liquid bitumen sealer to retard water intrusion into the base course and subgrade. Localized patch failures may also develop where trucks or buses turn on the pavement. When these occur, they should be cut out and patch repaired. The pavement sections above provide options to meet the ESAL requirements. Other pavement design options would be acceptable as well as long as they meet the minimum requirements for bituminous thickness, aggregate base thickness, and can meet the ESAL requirements. 4.3 Utilities Invert elevations for the culverts are anticipated to be within 5 feet of existing grades, and invert elevations for the watermain and sanitary sewer are anticipated to be between 8 and 13 feet below grade. Based on the borings, the subgrade soils for the utilities will consist chiefly of sands with silt and silty sands except at Boring PB -13 where organic soils are present. In addition, we recommend sand conforming to MnDOT Specification 3149.2F Granular Bedding be placed in the bottom of an unstable or wet excavation. The sand should have 40 percent by weight passing the #40 sieve and less than five percent (5%) by weight passing the #200 sieve. The granular bedding should be placed to at least the crown of the pipe. Trench backfill above this point may consist of the non-organic excavated soils once properly moisture conditioned. Underground utilities are expected to be installed by backhoes completing the excavations and placing fills. Soil compactors should be used to compact the fill in even lifts to the specified densities. 4.4 Dewatering Wet and saturated soils were encountered in the borings. Groundwater could potentially enter the excavations for deeper utilities. Dewatering in this area will likely require sand point wells. 4.5 Backfill and Fill Selection and Compaction The on-site non-organic soils may be reused as backfill and fill provided they are moisture conditioned and can be compacted to their specified densities. Any wet soils excavated would need to be dried before reuse as an engineered fill. Backfills with cobbles larger than six inches (6") should not be placed below pavements or in contact with utilities. We recommend that sandy soils be moisture conditioned to meet compaction specifications and clayey soils be moisture conditioned to within two percent (2%) below to three percent (3%) above their optimum moisture contents as determined from their standard Proctor tests (ASTM D-698). Fill should be spread in lifts of 8-10 inches for clays and 10-12 inches for sands, depending on the size and type of compaction equipment used. Geotechnical Report Oneka Lake Boulevard and Harrow Avenue Improvements Hugo, Minnesota WSB Project No. 010893-000 Page 8