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AMERICAN ENGINEERING TESTING, INC. AET Project No. 22-00012 <br /> We recommend that the fmal 12 inches of the clay subgrade be treated with Class C fly ash. The <br /> subgrade can consist of the on-site dark brown to black clayey topsoil. For preliminary design <br /> purposes, we estimate that treating the upper 12 inches of clay subgrade with about 10% by <br /> weight of fly ash would likely increase the R-value from 10 to about 20. Laboratory Proctor and <br /> CBR or Stabilometer testing would be required to confirm the estimated subgrade support <br /> parameters for this alternative. The actual required amount of fly ash will depend on the water <br /> content of the soil at the time of compaction. If you wish to pursue this alternative further, <br /> please contact us for additional information. We can also assist in preparing preliminary cost <br /> estimates for this alternative. <br /> 6.9.3 Subsurface Drainage <br /> Drainpipes should be installed in the sand subbase to remove infiltrating water. This can be <br /> accomplished by placing short segments of perforated drainage lines which are connected to <br /> catch basins at lower elevations (referred to as "finger drains"). Where the pavement is relatively <br /> level, and finger drains are not frequent, we recommend placing a series of longer parallel <br /> drainage lines through the level area to better remove infiltrating water. <br /> The final slope/shape of the subcut bottom prior to sand subbase placement should be such that <br /> water is directed to the drainage area. The subcut bottom should not include depressions which <br /> act as reservoirs for water collection. <br /> 6.9.4 Section Thicknesses <br /> For the traffic pattern typical of this type of parking lot, we recommend the following pavement <br /> sections; our recommended pavement sections without and with fly ash stabilization are <br /> presented in Tables B and C,respectively(see also Figure 2 in Appendix A). <br /> Page 23 of 28 <br />