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rw • The gravel sections presented below are bazed on the subsoil conditions observed along the proposed roadway, the assumed traffic loadings and the AASHTO Guide (or Design oC Pavement Structures (1986). The design calculations are shown in Appendix A. We recommend that the gravel section to be constructed for this roadway consist of a minimum of 8 inches of pit run gravels and 4 inches of road baze gravels. The new gravel section should be placed on the clays and claystone bedrock materials exposed along the roadway. Subgrade/Gravel Preparation: Prior [o placing the gravel sections on the new roadway, we recommend that [he exposed soils be scarified to a depth of 6 inches, brought to within 2 percent of the optimum moisture content and then be recompacted [o a[ leas[ 95% of the standard Proctor density determined in accordance with ASTM D698. a.ny fdl materials placed beneath the roadway should be placed in 6 to 8 inch lifts and compacted [0 95% of the maximum standard Proctor density. The new subbase gravels and base course materials placed on ttre roadway should be compacted [o at leas[ 95% of the maximum modified Proctor density at or near the optimum moisture content, determined in accordance with ASTM D1557. The baze course and subbase gravels should be approved by [be soils engineer, prior to placement. We recommend that the road base gravels placed on the roadways meet [he requirements For Class V or VI base course in accordance with the Colorado Department of Transportation specifications. (n addition, the subbase gravels should meet the requirements for Class II or Class III baze course. • Drainaee: The collection and diversion o[ surface drainage away from the roadway area is extremely important for satisfactory performance of the roadway. The design of surface drainage features should be carefully considered to remove all water from all roadway areas. In addition, the maintenance of all drainage structures should be conducted periodically to ensure proper performance. We recommend that the new gravel surface be constructed with a crown or super elevation of a[ least 2 percent. Limitations: This report has been prepared in accordance with generally accepted soil and pavement engineering practices in this area For use by the client for desigtt purposes. The conclusions and recommendations submitted is this report are based upon the assumed traffic loadings and [he data obtained from the test holes advanced along the subject roadway. If during construction, soil and ground water conditions appear to be different from those described herein, this office should be advised at once so that reevaluation of the recommendations may be made. We recommend the on- site observation o the ubgrade prool'rolling, gravel placement and compaction by a qualified soils engineer. Sincerely. Brian D. Len, Jt.E. ~j a~