Agenda - Public Works Committee - 04/16/2024

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We recommend bedding material be thoroughly compacted around the pipes. We recommend trench backfill above the pipes be compacted to a minimum of 95 percent beneath pavements, the exception being within 3 feet of the proposed pavement subgrade, where 100 percent of standard Proctor density is required. In landscaped areas we recommend a minimum compaction of 90 percent. 4.4 Pavement Recommendations The City of Ramsey may have standard plates that dictate bituminous pavement design. If so, we assume the pavements be designed in accordance with the appropriate standard plates. The following paragraphs provide general pavement recommendations in the absence of standard plates. Reconstruction In areas that will be reconstructed we recommend removing all vegetation and topsoil, if any, and all pavements, aggregate base and any soft or otherwise unsuitable materials from beneath the pavement subgrade. Prior to placing the aggregate base (Class 5) we recommend compacting the subgrade soils to provide a more uniform surface and to identify soft, weak, loose or unstable areas that may require additional subcuts. Backfill, if needed, to attain pavement subgrade elevation can consist of any mineral soil provided it is free of organic material or other deleterious materials but recommend additional fill, if needed, consist of soils similar to the soils at a particular local to reduce the potential for creating areas below the pavement section that could collect water. Granular fill classified as SP or SP-SM should be placed within 65 percent to 105 percent of its optimum moisture content as determined by the standard Proctor. Other fill soils should be placed with moisture contents within a range of 1 percentage point below and 3 percentage points above its optimum moisture content. The upper 3 feet of fill and backfill should be compacted to a minimum of 100 percent of its standard Proctor maximum dry density. Full Depth Reclamation For "Full Depth Reclamation" areas there may be instances where the recommended aggregate base thickness exceeds the existing aggregate base thickness. The preferred method of pavement repair would be to reclaim the existing bituminous, subcut the subgrade, replace the reclaim and add additional aggregate base as needed then construct the bituminous pavement. Subcutting the subgrade may not be feasible or cost effective. As an alternate it may be possible to use a thicker bituminous pavement along with the existing aggregate base or possibly subcutting some of the exiting aggregate base. Using MN/DOT granular equivalencies, one (1) inch of bituminous is equivalent to 2.25 inches of MN/DOT aggregate base. R-Values Laboratory tests to determine the soils Hveem Stabilometer R-Value (R-Value) was beyond the scope of this project. Subgrade soil conditions varied along the alignments and included both clayey and sandy subgrade soil. Table 4 provides a summary of the assumed subgrade R-values. These values were obtained from the MN/DOT, Geotechnical & Pavement Manual (2007). 11