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AMERICAN ENGINEERING TESTING, INC. AET Project No. 22-00012 <br /> possibly requiring additional maintenance before the final lift of bituminous is placed. <br /> In the new pavement areas, we recommend stripping the existing pavement and surficial topsoil <br /> to at least 2 feet beyond the edge of new pavements. After stripping the existing pavement, <br /> vegetative layer, and topsoil, and before placing new fill in the pavement areas, we recommend <br /> that the exposed clayey soils within 3 feet of the pavement elevation be evaluated for stability by <br /> test rolling. Unstable soils found during the test roll (generally soils that yield more than 1 inch) <br /> should be subcut and replaced, or scarified, dried and compacted until a passing test roll is <br /> achieved. <br /> If the remnants of the existing buildings on the site underlie the new pavement areas,they should <br /> be cut off at least 2 feet below bottom of new base course to avoid "hard spots" under the <br /> pavement that will be placed. We recommend that the bid documents contain a unit price line <br /> item for removal of old buried structures and utilities that cannot be seen from the surface but <br /> might be encountered. <br /> Because of the poor frost/drainage and the variable stability properties of the clayey soils on this <br /> site,we strongly recommend placing a sand subbase layer below the bottom of the base course in <br /> the new pavement areas. We recommend using a Modified Select Granular material for the sand <br /> subbase layer, such as Mn/DOT 3149.2B2 processed to have less than 40% passing the No. 40 <br /> sieve and less than 7% passing the No. 200 sieve. Drainpipes should be installed in the sand <br /> subbase to remove infiltrating water. We recommend that the subbase extend beneath the curbs <br /> and to 2 feet beyond the outside edge of the curbs, for frost and drainage uniformity. However, <br /> outside the curbs, the sand subbase should be capped with slow draining soil to reduce <br /> infiltration of surface water into the sand layer. Please note that the sand subbase has very little <br /> "binder" in it and will rut under construction traffic. Therefore, the aggregate base course will <br /> likely have to be placed by end-dumping so that the construction equipment can work off of an <br /> aggregate base course surface rather than the sand subbase. <br /> Page 21 of 28 <br />