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SP86 -039 - 5 - <br />M. W. Carley & Associates, Inc. <br />June 10, 1986 <br />over 2 inches of base course) placed on top of 8 inches of aggre- <br />gate base. The aggregate base should be placed upon 18 inches of <br />select granular material. Both the aggregate base and'underlying <br />granular material should be compacted to a minimum of 100% of <br />standard Proctor density (ASTM D698 -78). Regardless of the com- <br />bination utilized to achieve a G.E. of 25, to reduce the risk of <br />fines being "pumped" into the pavement section, we recommend that <br />a geotextile fabric be installed below the granular material. <br />Prior to the placement of the fabric, we recommend that the <br />subgradd soils be proof - rolled with a loaded dump truck to assist <br />in detecting any extremely soft areas. Extremely soft areas <br />should be subcut and stabilized. <br />It is our opinion that the inplace bituminous materials could be <br />recycled. Based upon one (1) bituminous extraction, the inplace <br />blacktop has an asphalt content of approximately 7 -1/2 %. <br />C.3• Ground Water Recommendation: As previously indicated, <br />ground water was observed in all of the bore holes at a depth of <br />7 to 8 feet immediately after withdrawal of the auger. Due to <br />the relatively impermeable nature of cohesive soils, several dayb <br />may be required for water levels to stabilize. Given sufficient <br />time, the ground water would likely stabilize at higher levels. <br />This being the case, ground water could be of significance from <br />design and construction standpoints. Since this street is pre- <br />sently in use, we have assumed that utilities are inplace. <br />However, future utility work could experience construction dif- <br />ficulties due to a high ground water level and wet soils. <br />Page 72 <br />