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AET #22-OO173- Page 5 of 10 <br /> Based on the soil conditions encountered at the boring locations and the proposed redevelopment <br /> plans, including filling of the existing basement, we have performed settlement estimates for the <br /> proposed redeveloped home. In our opinion, based on the existing conditions and proposed <br /> construction, differential settlements of 1'/2 to 2 inches may occur. These estimates are based on <br /> your Structural Engineer's estimate of required bearing pressure for the redeveloped home on the <br /> order of a maximum of 2,000 pounds per square foot (ps� and the City of Orono requiring that <br /> the existing basement be completely backfilled. If the basement is not backfilled, we estimate <br /> additional differential settlements of'/2 to 1 inch, based on the proposed consU-uction. <br /> To reduce the potential for harmful differential settlements, we recommend imposing a <br /> construction delay of at least 2 months following fill operations for the existing basement. This <br /> delay would allow primary consolidation of the existing fill and organic soils to occur and reduce <br /> the potential for long term differential settlements. During this time, the fill should be monitored <br /> with settlement plates to observe the consolidation of the underlying fill and organic soils. <br /> As an alternative, helical piles may be installed to reduce future settlement by underpinning the <br /> existing foundation. <br /> Based on the conditions found at the borings, we anticipate the garage addition will bear on <br /> undocumented fill or naturally-occurring non-organic soils, and we recommend that the spread <br /> foundations be designed for a maximum allowable soil bearing pressure of 2,000 pounds per <br /> square foot. lt is our judgment the recommended design bearing capacity should include a factor <br /> of safety of at least 3 against shear or base failure. We recommend the perimeter foundations for <br /> heated addition areas be placed such that the bottom is a minimum of 42" below exterior grade <br /> far frost protection. Interior foundations in heated areas can be placed directly below the floor <br /> slab. Exterior foundations (those noi bordering heated building areas) should be extended to a <br /> minimum of 60"below exterior grade. <br />