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Preliminary Report of Geotechnical Exploration <br />Main & Gates Redevelopment; Elk River, Minnesota AMERICAN <br />July 9, 2021 ENGINEERING <br />Report No. P-0001445 TESTING, INC. <br /> <br /> <br /> <br />Page 9 of 10 <br />Constructing a layer of NFS sand (beyond the basement wall NFS backfill) beneath exterior <br />entrances, sidewalks, and stoops will reduce heaving and associated trip hazards and other <br />problems. There should be tapered transition zones between the frost susceptible and non-frost <br />susceptible soils, and subsurface drainage will be required at the base of the NFS sand section. <br /> <br />Over the life of the sidewalk/entry slabs and pavements, cracks will develop and joints will open <br />up, which will expose the subgrade and allow water to enter from the surface and either saturate <br />or perch atop the subgrade soils. This water intrusion increases the potential for frost heave or <br />moisture related distress near the crack or joint. We recommend implementing a detailed <br />maintenance program to seal and/or fill any cracks and joints. The maintenance program should <br />give special attention to areas where dissimilar materials abut one another, where construction <br />joints occur, and where shrinkage cracks develop. <br /> <br />For further details, we refer you to the attached sheet entitled “Freezing Weather Effects on <br />Building Construction.” <br /> <br />7.0 CONSTRUCTION CONSIDERATIONS <br />7.1 Potential Difficulties <br />7.1.1 Runoff Water in Excavation <br />Water can be expected to collect in the excavation bottom during times of inclement weather or <br />snow melt. To allow observation of the excavation bottom, to reduce the potential for soil <br />disturbance, and to facilitate filling operations, we recommend water be removed from within the <br />excavation during construction. Based on the soils encountered, we anticipate the groundwater <br />can be handled with conventional sump pumping or be allowed to drain into the naturally <br />deposited sands. <br /> <br />7.1.2 Disturbance of Soils <br />The on-site soils can be disturbed under construction traffic, especially if the soils are wet. If <br />soils become disturbed, they should be subcut to the underlying undisturbed soils. The subcut <br />soils can then be dried and recompacted back into place, or they should be removed and replaced <br />with drier imported fill. If the sand soils used as fill become dry they should be wetted prior to <br />recompaction. <br /> Draft