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Brookview Estates Reconstruction <br /> Ramsey, Minnesota <br />NTI Project No. 18.MSP06855.000 <br /> <br />2.3Utilities <br />The fill and native soils observed in soil borings were generally suitable for utility support. Due to the <br />observed groundwater levels and depending on the installation depth of the utilities, temporary <br />dewatering would likely be required during the utility trench excavations for deeper utilities, such as <br />sanitary sewer. Stabilization of the trench subgrade may be required, in particular in locations with <br />lean clay subgrade, in order to provide a stable platform for construction. Stabilization could consist of <br />a one half to one foot layer of crushed rock or sand with a maximum 5 percent material passing the No. <br />200 sieve and 50 percent passing the No. 40 sieve. <br />The Geotechnical Engineer of Record or their designated representative should observe the project <br />excavations to determine that unsuitable materials have been properly removed and adequate bearing <br />support is provided by the exposed soils. The exposed soil at the base should be compacted with a <br />vibratory roller to 95 percent standard Proctor dry density (ASTM D698). Such observations and testing <br />should be performed prior to backfilling. <br />The on-site, non-organic soils are anticipated to be suitable for reuse if properly moisture conditioned <br />and compacted. Replacement backfill required in utility trenches should consist of non-organic material <br /> <br />It is especially important that trench backfill for utility construction within paved areas be thoroughly <br />compacted to minimize future pavement damage. We recommend that such soils be compacted in <br />accordance with the recommendations noted in <br />section in Appendix B of this report. <br />The stability of embankments along utility excavations is dependent on soil strength, site geometry, <br />moisture content, and any surcharge load for excavated soils and equipment. We present cautionary <br /> <br />The Contractor is solely responsible for assessing the stability of and executing underground utility and <br />project excavations usi <br />- OSHA). <br />2.4Pavement Recommendations <br />Full Reconstruction Option <br />The most conservative method of subgrade preparation would be to remove the undocumented fill <br />soils and replace them in their entirety with properly compacted engineered fill. This method of <br />subgrade preparation would provide the most uniform subgrade but would also be the most costly <br />method of construction and would be a relatively a-typical method of subgrade preparation for <br />improvements to existing municipal roadways. <br />If the City were willing to accept some risk in potential long term increased maintenance of the <br />pavement section for the significant upfront savings, the roadway can be reconstructed over the <br />existing fill. <br /> <br />Page 3 of 7 <br /> <br />