1920 MERRILL CREEK PKY 2018-01-01 MF Import

i I SHANNON&WILSON.INC. 8.2.4 i�dslide Dep�its and Fill IWithout subsurface information, it is assumed that the slope fill is non-engineeretl and loose. This is also suggested by other documents indicating end-dumped fill on the site. i I Cumently, the existing fill slopes are t1►ought to be muginally stable. This is supported by the follawing observations: 1) these soils are in a loose state, 2) fill soils W the south of the site have failed on slopes as steep as or flatter than portions of the site, 3) there is evidence of a possible scarp along the slope, as shown on Figure 1, 4) 1.SH:1V to 1.75H:1V are near the angle of repose of dumped fill, 5) stumps and debris were observed Iin the 811, 6) there is evidence of creep within the fill, and � 1Yiad Associates indicates mwements of old survey stalaes on the slope. IThe likely mode of failure with fill is also a planar, shailaw slide, which would tend I w occur during heavy tainfall or during a seismic event. As in colluvium, failure would not likely impact the proposed upslope development, but it could impact the property belaw. I 8.3 �D�C ta ion ISince the propo�ed buildings will be constructed on undisturbed, native, glacial soils, it is our opinion that the minimum 25-foot setback distance from the top of the slope (as required by EMC 19-8'n may be used in finalizing the development. These minimal setback distances will cornespond to a stability factor of safety of at least 2, pravided the Irecommendations below aze implemented. ► Although the 611 can stand vertically and suffer only a slow retreat wer dme because of its inherent erosional resistance, its slopes should be cut back to at � least 1H:1V w reduce the possibility of block falls. Addidonally, although highly resistant W erosion, the slope should be vegetated to reduce sediment dischazge Idownslope, by means established by the project landscape az�chitect. ► T'he outwash slopes should be cut back no steeper than 1.SH:IV. Vegetation or erosion-control geosynthetics will be required to control erosion. The project landscape architect should be consulted in this regard. IAdhecence to these slopes will require regrading the steep hillside areas shown on Figuce 2 to a flatter slope. The areas indicated for regrading on Figure 2 exclude a 5- to 10-faot-high I W-6693-01 12