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� <br /> � GEOTECHNICAL ENGINEERING STUDY <br /> Told Development <br /> � May 8, ]990 E-4R88 <br /> Page 8 <br /> � We recommend the apprupriate locations of subsudace drains, if needed, be established <br /> during grading operations by ECI's representative at which time the seepage areas, if present, <br /> may be more clearly ,iefined. <br /> � Pevement roo� <br /> � The adequacy of site pavements is strictly related to the rnndition of the underlying <br /> subgrade. If this is inad�eyuate, no matter what pavement section is constructed, settlement <br /> or movement of the subgrade will be reflected up through the paving, In ordcr to avoid <br /> . this situation, we recommend that the subgrade be treated and prepared as described in the <br /> Site Preparation section of this report. This means at least the top cwelve (12) inches of the <br /> subgrade shouid be compacted to 95 percent of the maximum dry densiry (per ASTM <br /> � D-1557-78). It is possible that some localizod areas o[ s�{� wet or unstable subgrade may <br /> sti1� exist after this process. If so, they may require overexcavation of the unsuitable <br /> materials and their replacement with a compacted structural 6�� or a crushed rock, <br /> � We recommend the following pavement sections: <br /> � � 71vo inches of Asphalt Concrete (AC) over four inches of�ushed Rock Base (CRg) <br /> material, or <br /> � • Two inches of AC over three inches of Asphalt Treated Base (ATB) material. <br /> The pavement section is based on ]ight automaUile tra�c and a subgrude R-value of 60 or <br /> � higher. If the traffic index should change and heary truck traffic increases, we should be <br /> contacted to re-evaluate our pa��ement design. Because of the genera] nature of the site <br /> soils, and if construcdon is likely to be conducted in the wetter winter months, we <br /> � recommend you select the ATB pavement section. This will not only provide you with a <br /> competent "blacktop" surface that wi11 help protect the site from construction activiry, but will <br /> also provide a clean, dry and competent surface on which to store and protect construction <br /> � materials. It has also been our experience that in spite of its slightly higher inidal cost, this <br /> form of surfacing requires considerably less maintenance either during or after a winter <br /> construction period. <br /> � <br /> � LIMITAT_� <br /> Our recommendations and conclusions are bazed on the site materials observed, selective <br /> laboratory testing and engineering analyses, the design information provided us by your <br /> � architect, and our experience and engineering judgement. The conclusions and <br /> recommendations are professional apinions derived in a manner consistent with that level <br /> of care and skill ordinarily exercised by other men�bers of the profession currently practicing <br /> � under similar condidons in this area. No warranty is expressed or implied. <br /> � Eerth Cona�ltents, Inc, <br />