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R-4 <br /> <br />overlay rehabilitation. Mill & overlay activities do not correct any issues with the <br />underlying subgrade materials or lack of compaction in the lower layers of <br />bituminous. Because a mill & overlay places new pavement on top of these <br />defects, these conditions will eventually break through the new layer of pavement, <br />creating voids where moisture can enter and cause freeze/thaw heaving and <br />potholes. This would reproduce the condition that Watertown Road is in now. <br /> <br />Due to the short pavement life of the mill & overlay alternative, a full depth <br />reclaim approach is recommended and evaluated in this study. This approach will <br />correct many of the underlying subgrade and compaction issues by pulverizing <br />and grinding the existing pavement down to an aggregate base that may be <br />prepped for a new bituminous surface. This method takes the pavement down to <br />a point where we can re-compact the newly created subgrade surface, adding <br />strength and eliminating voids where moisture can collect, and then apply a new <br />bituminous asphalt layer, eliminating many of the issues that are causing alligator <br />cracking and potholes. This new bituminous surface has an expected life of 20- <br />years, however with the underlying issues corrected, it may be maintained and <br />treated in the same manner as a new bituminous roadway. After a period of time it <br />may be chip sealed, seal coated, or even milled & overlaid, to prolong the life <br />beyond the 20-year estimate. <br /> <br />Because Watertown Road is a Municipal State Aid route, certain types of <br />reconstruction and rehabilitation methods would trigger a requirement by <br />MN/DOT for any improvements to meet State Aid Design Standards. Currently <br />the horizontal geometry and width of Watertown Road does not meet state aid <br />design standards, and will need to be modified if the road is reconstructed. There <br />are exemptions to this requirement for maintenance and rehabilitation that will <br />extend the life of the existing roadway without the need to meet State Aid <br />standards. Full depth reclamation is considered pavement rehabilitation that will <br />not trigger this requirement. . <br /> <br />Figure No 1 indicates the proposed street area to be reclaimed and replaced. Full <br />depth reclamation will pulverize and grind the existing bituminous asphalt surface <br />into granular material that may be compacted in place and become a suitable base <br />for a new bituminous surface. This will require the removal of some of the <br />existing material so that the rehabilitated pavement surface is at a similar <br />elevation as the removed surface. In the areas where there is significant distresses