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0 9 • <br /> • <br /> 8.0 CONSTRUCTION <br /> 8.1 SITE PREPARATION <br /> 8.1.1 Grubbing and Stripping <br /> Stripping-and grubbing will.be required at the site to remove vegetation that is at the ground <br /> surface. Where present,the existing root zone material should be stripped and removed from all <br /> proposed building and pavement areas. We anticipate a stripping depth of approximately <br /> 6 inches to 1 foot over areas of the site where native vegetation has grown. Greater depths may <br /> be necessary to remove localized zones of organic material or deeper root zones in loose upper <br /> material. The actual stripping depth should be based on field observations at the time of <br /> construction.''Stripping depths should extend at least 5 feet beyond the limits of proposed <br /> structural areas. Stripped material should be transported off site for disposal or used as fill in <br /> landscaped areas. <br /> 8.1.2 Subgrade Verification <br /> A member of our geotechnical staff should observe the exposed footing, foundation, floor slab, <br /> pavement, and driveway subgrade after stripping, excavation, scarifying and compaction, and <br /> placement of structural fill have been completed to confirm that there are no areas of unsuitable <br /> or unstable soil."Thesubgrade should be evaluated using moisture-density testing or a hand <br /> probe. If soft, loose, or otherwise unsuitable soil is found at the subgrade level, we recommend <br /> the soil be over-excavated and replaced with structural fill or stabilization material. We <br /> recommend the upper 24 inches of subgrade beneath footings, foundations, pavement, and <br /> floor slabs be properly compacted to 95 percent of the maximum dry density, as determined by <br /> ASTM D1557. <br /> 8.1.3 Permanent Slopes <br /> Permanent cut or fill slopes should not exceed.a.gradient of 2H:1 V, unless specifically evaluated <br /> for stability. Upsiope buildings, access roads, and pavement should be set back a minimum of <br /> 5 feet from the crest of such slopes. Alternatively,the setback at the top of the slopes can be <br /> determined on a case-by-case basis by the geotechnical engineer. Slopes should be planted with <br /> appropriate vegetation to provide protection against erosion as soon as possible after grading. <br /> Surface water runoff should be collected and directed away from slopes to prevent water from <br /> running down the face of the slope. <br /> 8.2 ,DRAINAGE..CONSIDERATIONS <br /> 8.2.1 Surface Drainage <br /> The finished ground surface should be sloped away from the structures at a minimum 2 percent <br /> gradient for a distance of at least 5 feet. Roof drainage from the structures should be directed <br /> into solid,smooth-walled drainage pipes that carry the collected water to the storm drain system. <br /> Pavement surfaces and open space areas should be sloped such that surface water runoff is <br /> collected`and`routed to-suitable discharge points..Runoff water should not be directed to the top <br /> of slopes. <br /> 8.2.2 Subsurface Drainage <br /> In our opinion, perimeter footing drains should be required considering the proposed below- <br /> grade,tuck-under structures will be embedded into the very dense glacial till material. <br /> GEODESIGN2 9 . NWHome-1-01:101618 <br />