Laserfiche WebLink
October 7, 2024 <br />ITT Project 24-327 <br />Various Gravel Roads <br />IP 25-07 <br />Ramsey, Minnesota <br />(SP-SM) and silty sands (SM) are considered excellent material for use as roadway subgrade <br />material. These soils are fairly easy to compact using vibratory compaction equipment near their <br />optimum moisture contents. <br />We recommend that any imported fill and utility trench backfill material consist of mineral soils <br />meeting the requirements specified below. No organic soils, roots, stumps, logs, brush, etc. <br />should be used as structural fill below any utility structure or pavement section. We recommend <br />that all fill and utility trench backfill material be free of soft, wet, or frozen soils, highly <br />expansive soils, rubble, debris, and rocks in excess of 6 inches in diameter. The fill material <br />should be as uniform as possible both in composition and moisture content. <br />No organic soils with organic content in excess of 3.0% by weight should be used as roadway <br />embankment fill or as subgrade material. Some of the fill was dark brown to black. However, it <br />is our opinion that most of the dark silty sand fill will be suitable for re -use. <br />The organic soils encountered on Xenolith Street in Area A were covered with at least 5 feet of <br />granular, inorganic fill. That means it is below the depth that would be affected by traffic wheel <br />loading. It is still likely to be affected by frost heave and some differential settlement. We see no <br />need to remove this material unless it is exposed during construction. <br />We recommend that all embankment fill material be placed in 12-inch loose lifts and compacted <br />to a minimum of 95% of standard proctor maximum density (ASTM D698). Any fill placed in <br />the top 3 feet of the road subgrade should be compacted to at least 100% of standard proctor <br />maximum density. All fill material should be compacted at a moisture content within plus or <br />minus 2% of the optimum moisture as determined by a standard proctor. We recommend <br />compaction tests be taken at a minimum rate of one test per two feet of fill per 200 linear feet of <br />roadway subgrade, and aggregate base material. <br />Page 8 <br />