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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 6 of 10 <br />placed which supports the floor slab only (outside of the 1:1 oversize zone below footings) for <br />cast foundation backfill or interior utilities can have a reduced minimum compaction level of <br />95% of the standard maximum dry unit weight. All fill should be placed at a moisture content of <br />+/- 2% of optimum as defined by the standard proctor test. <br /> <br />The excavated onsite soils can be reused as engineered fill, provided they are free of organics, <br />debris, and other deleterious materials. It is beyond our scope of services to determine the <br />volume of materials onsite that is suitable for reuse. Consideration of excavating a borrow area <br />in either a “green area” or possibly a parking area can also be considered to obtain naturally <br />deposited sand soils for the building pad fill. The borrow area can be re-filled and compacted <br />with on site fills placed according to MPCA Best Management Practices. <br /> <br />If imported soils are required, we recommend using sands with silt or sands meeting MnDOT <br />3149.2.B.2 Select Granular Borrow, similar to the existing site soils. The sand should be <br />classified as (SP) or (SP-SM). Frozen soils should not be used as fill and fill should not be <br />placed over frozen soils. If a different material is proposed, samples should be submitted to AET <br />for review. <br /> <br />If there are areas where fill is placed on slopes, we recommend benching the sloped surface <br />(benches cut parallel to the slope contour) prior to placing the fill. Benching is recommended <br />where slopes are steeper than 4:1 (H: V). <br /> <br />6.3 Foundation Design <br />The anticipated structure can be supported on conventional spread foundations placed on the <br />newly placed engineered fill or the natural alluvial soils. We recommend perimeter foundations <br />for heated building space is placed such that the bottom is a minimum of 48 inches below <br />exterior grade. We recommend foundations for unheated building space (such as canopy <br />foundations) be extended to a minimum of 60 inches below exterior grade. <br /> <br />Based on the conditions encountered, it is our opinion the building foundations can be designed <br />based on a net maximum allowable soil bearing pressure of 2,000 to 4,000 psf depending on the <br />location, depth, and building structural loads These soil bearing pressures would have a safety <br />factor of 3 with regard to ultimate bearing capacity. We recommend a minimum width of 30 Draft