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AMERICAN ENGINEERING TESTING, INC. AET Project No. 22-00012 <br /> poorly compacted fill is placed in the building pad, excessive building settlement could occur; <br /> this risk can be reduced by careful construction procedures and full-time observation by a <br /> Geotechnical Engineer or Materials Technician during fill placement. These risks can be further <br /> reduced by importing granular fill, such as Mn/DOT 3149.2B2 (as discussed above), which is <br /> less susceptible to disturbance during wet weather, easier to dry, and easier to compact. <br /> The fill in the building pads should be placed in lifts and compacted to at least 98% of the <br /> maximum Standard Proctor dry density(ASTM: D 698). Where the thickness of new fill exceeds <br /> 10 feet, we recommend that the compaction effort be increased to 100% of the maximum <br /> Standard Proctor dry density. Cohesive soils must be placed within 2% of the optimum water <br /> content. The fill should be placed in lifts thin enough to attain the specified compaction level <br /> throughout the entire lift thickness. This normally requires that fill be placed in loose lifts less <br /> than 8 inches thick. <br /> If sand fill is used to prepare the building pads over clay subgrades, there is a potential for the <br /> sand fill to hold water. A perimeter drain system at foundation level, inside and outside the <br /> building, could remove this trapped water. There could be a substantial volume of water <br /> infiltrating the sand fill during construction until the buildings are enclosed, roofed and exterior <br /> surface drainage provided. Providing an efficient means of removing this water could aid in <br /> reducing the potential for construction delays or disturbance of the building pad soils. If sand fill <br /> is not used inside the building pad,these drain systems would not be needed. <br /> 6.2 Building Pad Preparation Alternative No. 2—Aggregate Piers <br /> As an alternative to soil correction, we recommend that you consider improving the soils in situ <br /> with aggregate piers (stone columns or Geopiers ). With this alternative,the on-site topsoil and <br /> higher water content clay generated during mass grading of the parking areas could be used to <br /> raise the grade in the building pads. This would reduce the volume of soils that would have to be <br /> exported off-site. Soil contamination is known to exist on some parts of the site, and the <br /> aggregate pier alternative would also reduce the possibility of having to dispose of contaminated <br /> Page 13 of 28 <br />