3007 PANAVIEW BLVD 2016-01-01 MF Import

• September 2,1997 2 973-1164.100 The natural ravine slopes were between Z5 to 30 degrees on the upper slope,and appmximately 15 to 18 degrees on the lower slope. The geomelry of the slump we observed in May,1997 was relatively unchanged at the time of our field investigation in June,1997. The slope failure that occurred on your lot — on January 1,1997 resulted in a block of ground across the entire yard width undei che ; mncrete patio to drop about four to six feet in elevation. The patio cracked and broke in half and several of the support posLa for the entry level deck were undernuned. The — appmximate plan view geometry is shown on Figure 2,Site P1an. The type of slide that occurred on your property is referred to as a slump,which is characterized by the dawnslope movement of a relatively intact block of soil. The slump block v — approximately 70 to 75 feet in north-south width with a relatively level upper bench about 15 to 7A feet wide. The slope of the main scarp,which is the upper most ground break in the slope caused by a failure,is approxunately 40 degrees,and is located 5 to 10 ^ [eet horizontally from the east edge of your house. The main scarp can be traced south , of your property onto the adjacent neighbofs lot. The slope on the neighbors lot to the north experienced a mud/debris flow that stripped the upper surface of so$from the ' slope. The mud/debris flow abuts the slump on your lot. � The slope of the slump block is on the order of 25 to 30 degrees. The slope below the "� slump block is somewhat gender at about 15 to?A degrees. The surfaces of the slopes ; arn hummocky and are densely vegetated with trees and shrubs. Some tension cracks and associated minor slutnping was observed in the ravine at the eastern end of your �- property near the creek 3. FIELD INVESTIGATION Our field investigation was mmpleted on June 18,1997. The smpe of work included ' field mapping the surface features of the slope failure,geologic mntacts,and the . locafion of your house in relation to the failure. Several exploration staHons were locaMd in the vicinity of the slope failure and at selected areas of your property to assess ' the subsurface mnditions. These are shown oii Figure 2. At these stations we used . either a post-hole digger or hand auger to explorn the subsurface soil conditions. The subsurface soils wern examined and classified,and a topographic cross-section was ' preparnd through the slope failure,using a tape and clinometer. The site plan and cross , . sections presented in Figures 2 through 5 were mmpleted using field measuring equipment such as a measuring tape,hand level and clinometer. They should be ' mnsidered approximate. ' 4. RESULTS OP THE FIELD INVESTIGATION � 4.1 Geologic CondiBons ; � ,_, The geologic deposit�fortning the upland ridge where your house is located were � deposited by the advance and retreat of the Vashon stade glaciers about 12 to 15 •- Golder Assoclafes