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� C>j1 � <br />D:Ux <br />�Hy <br />N�� <br />�H� <br />'� I-xi'tl <br />U7 H <br />H <br />x� <br />O I—i � <br />H�g <br />�Y (� <br />C y � <br />HH <br />g �' <br />c� C w <br />�O� <br />� <br />C� <br />�� <br />f <br />� <br />a <br />DAVID L. NELSON AND ASSOCIATES, INC. <br />Cunsulting Enginccring Gculogy <br />Febc�iaiy 8, 1990 <br />Pza9ect No. 0890 <br />Page 4 <br />Excavation Consldecations <br />The depth of excavation and/oc stzuctuzal filling vithin the 6uilding a=ea <br />vill be dependent on the elevations chosen EoL Eoundation and flooi <br />elevations. Finished flooi elevations may cesult in eazth cuts and stzuctuxal <br />fills along upslope building/vall lines and do�nslope buildinq 1Lnes, <br />cespectively, Excavations that extend belov the gxound vatez could have <br />sevece consequences and potentially cause slope instability. We cecommend <br />that ve be retained to reviev excavation plans and to obsezve site conditions <br />ducing excavation to evaluate this potential. The use of cut-off oi fcench <br />dzains and flatteL cut slopes, may be necessacy to maintain slope stability. <br />A typical cut-ofF drain is attached to this repoet. This vould be determined <br />at the time of excavaticn. tie expect that the excavation Eor the stcuctuze <br />vill come close to if not intecsect the cuzrent giound vatec elevattons. <br />Stability of open excavation cuts vithin the sloping poztions oE the site <br />ducing constcuction vill depend on the natuce and consistency oE the naturally <br />occurxing soils, as vell as the ptesence of g=ound vat>i seepage and cunoi:. <br />The folloving temporary cut slopes a[e expected to be appropriate foz the[r <br />zespective soil types: <br />-2H to 1V foc loose sutficial soils. <br />-1.SH to 1V foc loose-medium dense silty sand and glacial dzift. <br />-1H to 1V for devatered medium dense-dense advance outvash saads, <br />�ith cut heights up to 10 feet. <br />Ample slope pcotection and maintenance should be used ductng construction. <br />Because of the many variables involved, the above values shouid be considezed <br />genetal guidelines. Unsuppocted peimanent cut slopes in medlum dense native <br />oz compacted sttuctucal fill soils should be no steepec than 2H to 1V. Once <br />speciEic plans aze developed, moce definitive infocmation could be pcovided. <br />Pezmanent fill embankments ace expected to stand at vazious slopes depending <br />on the matertal and compaction eftozt used. Foc stcuctural fill, that is Eill <br />comprised oE clean impozted ox on site soils vith a zelative compaction in <br />excess of 90� (aSTH D-1557), embankmer.t slopes should be no steepec than <br />