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SP86 -039 - 4 <br />M. W. Carley & Associates, Inc. <br />C. ANALYSIS AND RECOMMENDATIONS <br />June 10, 1986 <br />C.1. Design Data: It is our understanding that the length of <br />roadway to be upgraded is approximately 700 feet. It is our <br />understanding that the existing pavement section was designed for <br />5 -ton load limits. The roadway is to be upgraded to a 7 -ton <br />bituminous section design. <br />C.2. Roadway Design: It is our opinion that the existing pave- <br />ment distress is a result of poor subgrade soils combined with a <br />thin pavement section. To produce a 7 -ton roadway design, we <br />recommend that the existing pavement section be removed and <br />replaced with a thicker section. <br />The pavement section used for this roadway will be a function of <br />the type of subgrade materials which exist. From a roadway <br />design standpoint the .clay soils are considered the dictating <br />subgrade materials. Several bag samples of these soils were <br />returned to our laboratory so that Hveem- stabilometer R- values <br />could be determined. Bag sample #1 from boring B -1 and bag <br />sample #2 from boring B -2 were combined, representing the predo- <br />minant lean clay encountered on this site. This sample was <br />determined to have an R- value'of 2. <br />It is our opinion that the predominant clays encountered are con- <br />sidered poor subgrade soils with a medium to high potential for <br />frost heaving. Therefore, to produce a pavement section capable <br />of supporting 7 -ton loads, we recommend a pavement design uti- <br />lizing a granular equivalent (G.E.) of 25. <br />To achieve this gravel equivalent, one alternative would be to <br />utilize a 4 -inch thick bituminous layer (2 inches of wear course <br />Page <br />BR/1UflM <br />