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AET#22-00173- Page 6 of 10 <br /> Based on the proposed construction, this should limit total and differential settlements of the <br /> addition to ] inch and '/2 inch or less, respectively, provided that the bearing soils are not <br /> disturbed; wet or frozen at the time of construction. The specifications should include a note ihat <br /> the contractor must avoid disturbance or freezing of the bearing soils. <br /> Structure Backfillin� <br /> We recommend not using the clayey backfill in the basement or around the new foundation walls <br /> because clay can be difficult to compact in confined spaces. Rather, select soil such as Mn/DOT <br /> 3149.2B2 processed to have less than 12% passing the No. 200 sieve should be imported for the <br /> backfill. On-site cohesive soils could be used in the upper 1 feet of backfill and sloped away <br /> from the new home to direct run-off away from the foundation and to reduce surface water <br /> infiltration into the sand backfill. <br /> The backfill for the basement and around the newly constructed foundation walls should be <br /> placed in lifts, and mechanically compacted with manually operated equipment to at least 95% of <br /> the maximum Standard Proctor dry density (ASTM D 698). The fill should be placed in lifts thin <br /> enough to attain the specified compaction level throughout the entire lift thickness. This <br /> normally requires that fill be placed in loose lifts less than 8 inches thick. Large towed or self- <br /> propelled compaction equipment should not be used within 4 feet of the walls since this <br /> eyuipment could damage the walls, and impart permanent lateral stresses against the wall which <br /> are not accounted for in the structural design. The backfill should not be loosely dumped, nor <br /> should it be compacted by "puddling"or flooding. <br /> Floor Slabs <br /> Any new fill placed to attain floor slab subgrade, including utility and foundation trench backfill, <br /> should be compacted to a minimum of 95% of the maximum Standard Proctor dry density <br /> (ASTM D 698). Due to the frost susceptible soils found near the surface in the boring locations, <br />