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� <br />� �` <br />� <br />��� � <br />>HsV� <br />y zH � <br />� H� <br />� y'�H9 i�1 <br />Zo <br />� H� l� <br />�/��g <br />y� V C] <br />�y� ,,� <br />HH <br />N <br />gdy . <br />��M <br />x H Vi <br />H O fn <br />i <br />� � �t <br />� <br />�,��j i� <br />� ( � <br />0 <br />�DAVID L. NELSON AND ASSOCIAT[5, INC. <br />Consulting Enginccring Gcolugy <br />M.�rch 20, 1990 <br />Fcoject No. 2890 <br />Page 5 <br />Stability of open e�:cavation cuts within the sloping portinr.s of the site <br />during construction will depend on the nature and consistency of the naturally <br />occurring soils, as well as tt,e presence of ground water seepa9e and runoff. <br />The following temporary cut slopes are expected to be appropriate for their <br />respective soil types: <br />-2N to 1V for loose surficial soils. <br />-1H to 1V for medium dense weathered glacial till. <br />-0.75H to 1V fcr dense 9lacial till with cut heights up to 8 feet. <br />Ample slope protection and maintenance should be used during construction. <br />Because of the many variables involved, the above values should be considered <br />general guidelines. Unsupported permanent cut slopes in dense native or <br />compacted structural fill soils should be no steeper than 2ti to 1V. <br />Structural Fills <br />Permanent fill embankments are expected to stand at various slopes depending <br />on the material and compaction effort used. For struc hiral fill, that is fill <br />comprised of clean imported or on site soils with a relative compaction in <br />excess of 90� (ASTM D-15571, embankment slopes should be no steeper than <br />2H:1V, and propeily protected from erosion. All fill placed downslope of the <br />building site, if used, should be placed as structural fill. All fill areas <br />should be observed and apprcved by the 9eotechnical consultant. Absolutely no <br />filling should be performed upon the sloping portions of the site, including <br />"temporary" foundation excavation spoils, witt�out pricr approval and <br />observation by the geotechnical consultant. <br />Foundations <br />In our opinion, the use of shallow spread footings founded on the native, <br />I�! undisturbed glacial till deposits should prove suitable for support of the <br />proposed dwelling. For footings placed within th=_ glacial till as discusscd <br />�.4 below, an allowable bearing pressure of 3000 pouncs per square foot (psf) map <br />be used. Within the sloping portion of the site, ve su9gest tliat "stepped" <br />type footings be used, where excavation is performed into the dense glacial <br />till for footing pla�e�nent. We recommend that the footings be placed a <br />q <br />1 <br />