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Geotechnical Report 2018 PMP Streets Arden Hills, Minnesota WSB Project No. 010111-000 Page 5 4. ENGINEERING ANALYSIS AND RECOMMENDATIONS 4.1 Discussion Fills No information was provided to us regarding density tests or placement observations for the existing fills encountered at the boring locations. Generally, fills that are not documented are recommended for removal and replacement with an engineered fill. However, these fills were likely placed as fill for the pavement section. In our opinion, these fills can be relied upon as pavement support, however, a partial subcut, surficial compaction of the existing fills, and observations and testing during constr uction would lessen the risk of detrimental settlements. Organics Organic soils and vegetated root zones are not suitable for pavement support, and should be removed from within 3 feet of the top of subgrade. Additionally, we recommend peat be removed from within 4 feet of the top of subgrade. Based on a review of the boring logs, it appears that the organics and peat encountered in Boring PB-9 and PB-15 already meet these recommendations. Boring PB-16 appears to be outside of the roadway area. Additionally, underground utilities placed within organics have a high risk of total and differential settlement. In these areas, it is recommended to completely remove the peat or organic clays, support the utility pipe on helical piles, or subexcavate 3 feet and use a lightweight aggregate as the stabilizing bedding. Alternately, use of flexible pipe connections and/or geogrid in the pavement section could reduce damage from differential settlement. Where organics are excavated for utility placement, they should not be reused as backfill. A lightweight backfill should be considered to prevent increased loads on any existing organic soils below the utility pipe. Any increased loads present risk to the utility pipe or pavement section from total or diffe rential settlements. Fine Alluvium The lean clays encountered were generally wet and soft, and should be partially subcut and replaced with an engineered fill. Glacial Tills The glacial deposits were generally suitable for support of pavement sections and utility pipe. Where soft/wet clays are encountered, we recommend a subcut and replacement with engineered fill. General Generally, the soils in the upper 4 feet of the su bgrade influence pavement performance the most. The soils within the pavement subgrade consists mainly of clayey soils, which are frost susceptible. Consideration should be given to partially subcutting these soils and replacing with a non -frost susceptible granular fill to reduce the potential frost heave below the pavement section. 4.2 Pavement Areas Table 2 below presents the existing pavement section thicknesses and the subgrade soils encountered below the pavement.