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�" <br />� <br />; <br />� <br />� ' C'� <br />DAVID l. NEISON AND ASSOCIATES, IMC. <br />Comulti� En�ineerin� Gaolo�y <br />August 29. 198j <br />Pro3ect No. 4183 <br />Page tive <br />� <br />Roadrra�y developaenL is underatood to be perio�ed Mithirt the <br />steep area juet rreaL oi Narbeck Road and continue up She c�ntral � <br />s.+ale area onto the upland areaa. PrePaz'ation of th� rnadn�y <br />within the ontrance area ms�y require excavation into the slop� are: <br />We sug8eat atabilisation methoda be utiliaed v►ithin this aeva to � <br />maintain slope atability. Soils Mithin this area ars ezp�et�d to <br />conaist of the glacial till and glacial outaaeh doils r►ithin th� <br />upper elevationst horever, the finer �'ained Mhidbey Foraition <br />soila may also be encountered. Since adequate inloivsLion is <br />not availaDle rvithin this area, we au88est inter� roadway dati�s <br />and stabilizaLion utilise either a?Ji�1V backeloping of th� slops <br />area or the uae of a moderate aiaed retaininB nall uona Lha Soe- <br />of-slope nrea. If the slope area ia found to be rslatively eLable <br />during ':he course of roadway conetruction, a rock�ry protection <br />method could be utilized in lieu of bac§sl�ping or retaining rvalie <br />Removal and replacement of the organic aurficial soila ie racom- <br />mended ':hroughouti the roadna�y area, particularly within the <br />central sv�ale area. The organic material ehould be r�moved and <br />repla�ed usinp, granular structural fill, generally approved for <br />use within the azea. Any excavation slopes within thie area <br />should utilize a nominnl 2}i�1V backalope and Da rewgstattd to <br />reduce potential erosion. Conventional pavement das:gn ehould <br />be suitable within the prepared road areas. <br />Filling or excavation should not be perfarmad within Lh� set-back <br />area or over the steep slopes. Surface water ahould not be <br />allowed to Preely flow over the steep slope az'eae. <br />Vegetation removal is understood to be desired within portiona <br />of the set-back and steep slope areas. We suggeat thaL iS ar�y <br />vegetation is to be removed, that it be selective in nature and <br />performed auch that stability oS Lhe alope areas ie maintained. <br />Where larger trees are to be cut, we suggest that the stumpe <br />be allowed to re�cain, and that underbrush be undisturbed. Ar�y <br />removal of logs or slash along the slope areas should be per- <br />formed such thaL disturbance to the ground surface ia minimized. <br />J!/ <br />� <br />