4841 GLENWOOD AVE 2021-06-09 - Laserfiche WebLink

Retaining Wall Recommendations Page 2 August 21,2019 Everett,Washington RG1 Project No.2016-072 the slope and seismic accelerations for the pseudo-static analysis in the program. The site is mapped as glacial till,therefore the site class for seismic design is Site Class C. A reduced phi angle was used for the retained fill to account for the soils conditions expected in the cut slope beyond the reconstructed area that will be backfilled with structural fill. The drainage specification and limits are shown on the plan sheet W-1 provided as part of the plan set. The installation of the drainage in accordance with the detail will allow for water to flow slowly between the blocks therefore the wall is not designed for hydrostatic pressure. The slope above the wall will be landscaped and should be provided with a minimum of 12 inches of amended soils. We expect the onsite soils can be mixed with compost to provide this layer. The slope fill soils below the amended soils are expected to consist of the native soils compacted as structural fill and should route water that infiltrates through the amended soils to flow to the wall drainage. An example of the look of the finished wall with a slope above is provided on W-1 from a project recently completed.Although the blocks do not have a textured finish,the stacking of the blocks in the correct configuration provides a variable look due to the coursing of the blocks and the running bond construction similar to the look of large bricks. The slope above the wall will be landscaped after the completion of the wall. A fall protection railing will also be installed and can be either installed with posts excavated behind wall or bolted to the blocks at the top of the wall. Erosion and Sediment Control Potential sources or causes of erosion and sedimentation depend on construction methods,slope length and gradient,amount of soil exposed and/or disturbed,soil type,construction sequencing and weather. The impacts on erosion-prone areas can be reduced by implementing an erosion and sedimentation control plan.The plan should be designed in accordance with applicable city and/or county standards. RGI recommends the following erosion control Best Management Practices(BMPs): > Scheduling site preparation and grading for the drier summer and early fall months and undertaking activities that expose soil during periods of little or no rainfall ➢ Installing siltation control fencing or anchored straw or coir wattles on the downhill side of work areas > Covering soil stockpiles with anchored plastic sheeting ➢ Directing runoff away from exposed soils and slopes ➢ Minimizing the length and steepness of slopes with exposed soils and cover excavation surfaces with anchored plastic sheeting > Confining sediment to the project site Inspecting and maintaining erosion and sediment control measures frequently (The contractor should be aware that inspection and maintenance of erosion control BMPs is critical toward their satisfactory performance. Repair and/or replacement of dysfunctional erosion control elements should be anticipated.) Permanent erosion protection should be provided using hydroseeding and/or landscape planting. Until the permanent erosion protection is established, site monitoring should be performed by qualified personnel to evaluate the effectiveness of the erosion control measures. Provisions for 111LEYG It