1707 SCENIC DR SNO CO PUD Geotech Report 2022-10-25

within the fill in some of the explorations at the site. Accordingly, the contractor should be prepared to deal with boulders and concrete debris and abandoned foundations, if encountered. Temporary Cut Slopes The loose to medium dense weathered glacial soils encountered at the site is consistent with Type C soils by Washington Industrial Safety and Health Act(WISHA). We recommend that temporary slopes in excess of 4 feet in height constructed in loose to medium dense on-site soils be inclined no steeper than 1.5H:1V for Type C soils. The dense glacial till and soils are consistent with Type B soils and temporary siopes in excess of 4 feet in height may be inclined no steeper than 1H:1V. If significant seepage is present on the cut face of the slopes then the cut slopes may have to be flattened. However, temporary cuts should be discussed with the geotechnical engineer during final design development to evaluate suitable cut slope inclinations for the various portions of the excavation. For open cuts at the site we recommend that: ■ No traffic, construction equipment, stockpiles or building supplies be allowed at the top of the cut slopes within a distance of at least 5 feet from the top of the cut. s Exposed soil along the slope be protected from surface erosion using waterproof tarps or plastic sheeting. ■ Construction activities be scheduled so that the length of time the temporary cut is left open is reduced to the extent practical. ■ Erosion control measures be implemented as appropriate such that runoff from the site is reduced to the extent practical. ■ SurFace water is diverted away from the excavation. e The general condition of the slopes be observed periodically by a geotechnical engineer to confirm adequate stability. Permanenf Slopes We recommend that permanent cut and fill slopes be constructed no steeper than 2H:1V. Construction and regrading of permanent slopes should be completed as described in the "Slope Construction and Regrading"section above and as shown on Figure 4. To reduce erosion, newly constructed slopes should be planted or hydroseeded shortly after completion of grading. Until the vegetation is established, some sloughing and raveling of the slopes should be expected. This may require localized repairs and reseeding. Temporary covering, such as clear heavy plastic sheeting,jute fabric, loose straw, excelsior matting or other rolled erosion control products should be used to protect the slopes during periods of rainfall. Erosion and Sedimentation Control Potential sources or causes of erosion and sedimentation depend upon construction methods, slope length and gradient, amount of soil exposed and/or disturbed, soil type, construction sequencing and weather. Implementing an erosion and sedimentation control plan will reduce the project impact on erosion-prone areas. The plan should be designed in accordance with the City of Everett, Snohomish County and/or State of Washington standards. The plan should incorporate basic planning principles including: ■ Scheduling grading and construction to reduce soil exposure. GEOENGINEER� October24,2014 Page 11 Fle No.0482-027-02