1920 MERRILL CREEK PKY 2018-01-01 MF Import

� SHANNON F�WILSON.INC. maloes this material vulnerable to weathering, as related to wind, fneeze/tl►aw effects, and erosion from rainfall and surface water 8ow if not properly sloped and vegetate�. The thick clay and silt geologic unit that commonly underlies the outwash in the Puget Sound az.:a is I not exposed here. However, based on the water-holding capability of the lazge pond to the east of the slope at the south end of the site, it is possible that the silt and clay are near the Ibottom of the slope. 5.3 Colluvium � Colluvium comprises the steep slopes that lie immediately below the vertical or near-vertical Ibluffs on the site. The wlluvial slopes range from 35 to 45 degrees and are very loose. In some of the am,as below the steep, unvegetated bluffs, thete is little vegehadon on the slopes Ibecause of the accumulation of material from the 611 and outwash bluffs above. I5.4 Landslide Deposits I �)ne area of slope inshability was observed just south of the southeastem property corner (see Figure 1). This area had 2- to 4-foot setdowns on the side; however, the headscarp area was obscured by sod and concrete debris. The slide appeared to be located entirely in fill Isoils. � In addidon, a 4- to 10-foot-high linear scarp was observed in the central portion of the site, extending for a distance of about 400 feet (see Figure 1). Abave the scarp the slope was inclined at 12 to 14 degrees, and below the scarp the slope angle ranged from 27 to 33 degrees. The scarp was inclined at about 45 to 60 degrees and wes unvegetated. The slopes uphill and downhill wece both cwered with small-diameter trees and moss. The soils � dawnslope of the scarp were idendfied as fill. This featuce may be the scarp of a landslide, the surface acpression of widespread setdement of the downslope fill, or a remnant of the Ifilling of the downslope portion of the slope. T'he actual cause cannot be determined without subsurface ezplordtions. Hawever, basad on the known mechanism of slope Siling (end- Idumping), as dceumented by othe�, it is probable that some cmep is occurring. Additionally, a few fcet of observed mwement in old survey shakes, as noted by the I surveyors from TYiad Associates during current site mapping, supports the probability that some creep has occurred. IW-6693-01 5