CCP 01-31-1994 - Laserfiche WebLink

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I .. AET #93-1379 - Page 12 " The above-referenced specification also includes moisture content range requirements. This I moisture range should be closely evaluated for silty and clayey soils. I Subgrade Soil Factors/R-Value No actual R-value testing was conducted to aid in determining subgrade soil strength. However, I based on our experience and on charts developed by MnDOT, we offer the following chart to aia your selection of the appropriate soil strength parameter for the pavement section thickness I design. I .....................'."....'_...-.-,....,-.. .SoiJI'aCtOtjP~t.Fi~. .....JJ5~89~.201MnDOT I .' $lllteAid Manual 2' + Granular Keithson Drive Borrow over Clays A-2-4 over A-6 75% 45 .. Remaining Streets, no sand layer Clays A-tJ 110% 20 I Remaining Streets, l' Select Granular A-3 (or near l' Select Granular over Clays A-3) over A-6 100% 35 Remaining Streets. 2' Select Granular A-3 (or near I 2' Select Granular over Clays A-3) over A-6 75% 45 I Note: The above applies for the case of reconstruction only. If the subgrade were not prepared to proper stability within the upper 3' zone, lower values would be recommended. I Subgrade Drainae:e I The sub grade approach recommended herein will create a situation in the upper sub grade where granular soils overlie clayey soils. Because of this, water may become trapped within the I granular layer. To prevent trapping and build-up of subgrade water, we recommend sand layers be drained by a means of subsurface drainage. Where roadways are reasonably sloped, water ''e will tend to naturally migrate towards the lower elevation areas. In this case, finger drains tapped into catch basins can provide an outfall for the sand layer. However, where roads are flat (such as Amble Drive) we recommend placing parallel drain lines along the length of the I I