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-r <br />1 <br />SP88 -050 - 5 - <br />M. W. Carley & Associates, Inc. <br />June 2, 1988 <br />Using this R -value and with the assumed traffic loads, we <br />recommend that pavement sections on this material be designed <br />using a Granular Equivalent (G.E.) of at least 12. <br />If cohesive soils are encountered in portions of the subgrade, we <br />recommend the pavement section be designed using the Granular <br />Equivalent indicated in our previous report (G.E. = 25). <br />When designing the pavement, we recommend that the bituminous <br />portion of the pavement be at least 3 inches thick. It may be <br />possible to recycle portions of the existing bituminous and reuse <br />the aggregate. Evaluation of these materials are, however, <br />beyond the scope of this investigation. <br />C.3. Subgrade Preparation: To reduce the risk of localized <br />pavement distress, prior to placing any base materials, we <br />recommend that all roadway areas be proof - rolled with a loaded <br />dump truck to assist in detecting "soft" areas. Any soft areas <br />noted during the proof- rolling process should be subcut and <br />refilled with compacted soils. The backfili material should <br />consist of soil types similar to those which predominate below <br />the affected area and should be compacted a minimum of 100% of <br />standard Proctor density (ASTM D698). We recommend that one of <br />our soils engineers observe the proof -roll process and assist the <br />contractor in determining the depth and extent of any subcutting. <br />C.4. Groundwater Recommendations: As previously indicated, <br />groundwater was observed in four of the bore holes at a depth of <br />about 7 feet immediately after withdrawal of the auger. Due to <br />the relatively impermeable nature of cohesive soils, several days <br />may be required for water levels to stabilize. Given sufficient <br />time, the groundwater would likely stabilize at higher levels. <br />Page 76 <br />uRAnn'M <br />