Agenda - Council - 03/23/1982 - Laserfiche WebLink

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Con~ulting Engineers Diversified, Inc. February 11, 1982 Page 5 Based on the available information, we recommend that certain areas of frost susceptible soil and slightly organic soil encountered to a depth of 4 to 5 feet below the surface be removed. These areas are identified on Table 1, included in the Appendix. If.a soft/loose areas besides those identified at the boring locations are identified, they should be also removed. However, a simple pit'should not be dug and.the deleterious materials removed. Rather, such soils should be removed gradually with depth to prevent trapped water occurrences. Drainage considerations should include either catch basins with knockouts, if the roadway is planned with curb and gutter, or sloping the subgrade soils both parallel and perpendicular to the roadway with possible gravel drains to excavated ditches. We ~trongly recommend that you meet with uS' · during the preparation of plans so that adequate drainage is included in the design. The R-Value (Hveem Stabilometer Value) has been estimated for the pavement subgrade soils. These values are included on Table 1. Where anexcavation has been recommended to remove frost susceptible and organic soils, the' R-Value given is for the underlying subgrade soils beneath the cut. Generally, the R-values ranged from as low as 30 for plastic clay and silt areas to as high as 55 where the subgrade soil is a relatively clean sand. A free-draining granular fill would be recommended to attain final grade, provided drainage is included in the design. A suggested, gradation 'for granular fill is included with this letter. It is important that the fines (that. soil passing the No. 200 sieve) not exceed 8 to 10 percent by dry weight. Studies have shown that sand-gravel mixtures with greater than 10 $OILTESTINGSERVICESOFMINNESOT~INC.