3815 SHORE AVE 2020-05-20 - Laserfiche WebLink

Geologically Hazardous Areas: Geotechnical Letter Kennedy Single Family Residence 3815 Shore Avenue March 23, 2018 RN File No. 3279-001A Page 7 conducted during the drier months. Additional expenses of wet weather or winter construction could include extra excavation and use of imported fill or rock spells..During wet weather,. alternative site preparation methods may be necessary. These methods may include utilizing a smooth-bucket trackhoe to complete site stripping and diverting construction traffic around prepared subgrades. Disturbance to the prepared subgrade may be minimized by placing a blanket of rock spalls or imported sand and gravel in traffic and roadway areas. Cutoff drains or ditches can also be,helpful in reducing grading costs during the wet season. These methods can be evaluated at the time of construction. Temporary and Permanent Slopes Temporary cut slope stability is a function of many factors, such as the type and consistency of soils, depth of the cut, surcharge loads adjacent to the excavation, length of time a cut remains open, and the presence of surface or groundwater. It is exceedingly difficult under these variable conditions to estimate a stable temporary cut slope geometry. Therefore, it should be the responsibility of the contractor to maintain safe slope configurations, since the contractor is continuously at the job site, able to observe the nature and condition of the cut slopes, and able to monitor the subsurface materials and groundwater conditions encountered. For planning purposes, we recommend that temporary cuts in the near-surface outwash soils be no steeper than 1.5 Horizontal to 1 Vertical '(1.5H:1 V) per WAC 296-155-66403. Cuts in the stiff silty transitional beds may stand at a 1 H:1 V inclination or possibly steeper. If groundwater seepage is encountered, we expect that flatter inclinations would be necessary. We recommend that cut slopes be protected from erosion. Measures taken may include covering cut slopes with plastic sheeting and diverting surface runoff away from the top of cut slopes. We do not;recommend vertical slopes for cuts deeper than 4 feet, if worker access is. necessary. We recommend that cut slope heights and inclinations conform to local and WISHA/OSHA standards. Final slope inclinations for granular structural,fill and the native soils should be no steeper than 2H:1 V..Lightly compacted fills, common fills, or structural fill predominately consisting of fine grained soils should be no steeper than 3H:1V, Common fills are defined as fill material with some organics that are "trackrolled" into place. They would not meet the compaction specification of structural fill. Final slopes should be vegetated and covered with straw or jute netting. The vegetation should be maintained until it is established. Temporary shoring is not part of this geologic evaluation letter. Foundations Shallow: Conventional shallow spread foundations should be founded on undisturbed, medium dense or firmer soil. if the;soil at the planned bottom of footing elevation is not suitable, it should be overexcavated to expose suitable bearing soil, Footings should extend at least 18 inches below the lowest adjacent finished ground surface for frost protection. Minimum foundation widths should conform to IBC requirements, Standing water should not be allowed to accumulate in footing trenches. All loose or disturbed soil shouldbe removed from the Robinson Noble, Inc;