3210 36TH PL NE 2018-01-02 MF Import

• :�egrccate stockpilcs �t�ili induce setdement extending some distance away from the stuckpilc location. Wc recommend a 20-foot minimum setback from the toe of a stockpilc to any i setdement-sensi[ive structure. I These g�oteclmical issucs and other cansiderations are discussed further and recommendations pertainine ro the geotechnical aspects of the project are pr�scnted in the following sections. I EARTHWORK Erosion and Sedimentation Contro! Potcntial sources or causes of erosion and sedimcntat�en depend upon construction methods, slope Icngtli and gradient, amount of soil exposed and/or disturbed, soil type, constniction sequencing and wcather. The project impact on erosion-prone areas can bc reduced by implementing �n erosion and sedimentation control plan. The plan should be designed in accoruancc with the city of Gr�crett ancL'or applicable �ounty standards. The plan should incorporate basic planning principles including: i • Scheduling grading and construction to minimize soil exposure, • Retaining existing vegetation �ahene��er feasiblc. � • Revegetating or mulching denuded areas, • Directing runoff away Gom denuded areas, • Minimizing the length and steepness of slopes ��ith exposed soils, • DecreasingrunoCCvelocities, • Preparing drainage ways and outlets to handle concentrated or increased runoft; • Confining sediment to the project sitc, and • [nspecting and maintaiuing control measures frequenUy. Cemporary erosion protection should be used and maintained in areas with exposed or diswrbed soils to hclp minimize erosion and reduce transport of sediment to adjacent areas and receiving waters. Perniancnt erosion protcction should Ue providcd by re-establishing vegetation by hydroseeding or landscape planting. Until Qie permanent erosion protection is established and the site is stabilized, site monitoring should be performed by qualiticd personnel to evaluate the effectiveness oF the erosion control measures and repair odifications to the erosion control s stem bascd on and/or modify them as appropriatc. Provisions for m y monitoring observations should be included in the erosion and sedimentation control plan. Excavation Consideretions Surticial soils consisting of till and soft native organic silt were obsen�ed in the explorations. \Vc anticipate that thesc materials can be excavated with conventional excavation equipment, such as excavators or dozers. Ho�vever, due ro the soR and wet nature of the natice fine-grsined soils, we rccommend that d�e cantractor use low ground pressure cquipment including wide-tracked dozers, when operating over the native soils. In addition, �vc recommend that all excaaations by excavawrs be ❑ccomplished using a bucket with a smoodi edge to reduce disturbance ro the nati�e soils, especially when perForming excavations in areas under planned structures. 'i FilcA'o.8987-004-00 P4S�L'6 �iE0EN61NEER� ', Oc�oGcr ll,?006