3007 PANAVIEW BLVD 2016-01-01 MF Import

SepMmber 2,1997 4 973-1164.100 Fill was visible in the exposed main scarp and was enmuntered in HA-1 from the near surface to 10 feet,in HA-2 from the near�urface to a rnfusal depth of 9 feet,and —, in HA-3 from the surface to a depth of 11.5 feet. The fill material was relatively mnsistent in all of the explorations,mnsisting of a loose to mmpact,dusky yellowish brown,coarse to fine sandy and gravely clayey silt with abundant organics and — wood debris. Small clasLv of cveatheced till wern present in the fill. The approximate geologic mntacfs in the landslide area am shown in Cmss Section GC' —' on Figure 2. 4.2 Other Site Conditione There were no visible drainage oudets from your house discharging into the vicinity of the slope failure. However,several small 2 inch PVC pipes were observed in portions of — the brokem m�crete patio,as seen in Figure 2. The purpose of these pipes was not deternuned. There is a flexible PVC drain pipe just south of the cement wall on the south perimeter of your property,presutnably a drainage outlet from the house on the — adjacent lot This drainage feeds directly into the vicinity of the slope failure. Groundwater was enmuntered in HA-1 at a depth of 10.5 feet,and the weathernd till — sample at this depth was saturated. It appears that tt�e groundwater is located at the fil1/weathered till mntact,presumably perched on the underlying dense till. 5. CONCLUSIONS AND RECOMMENDATIONS 5.1 General The slope Eailure appeared to have occurred im m�junction with the mud/debris flow on • the adjacent Frishman lot in surficial,sahuated fill. The fill material mantling the , underlying dense glacial soils became saturated during the heavy snowfall and subsequent rapid melting accompanying heavy rainfall. The saturation of the loose fill ' initiated the slump failure. The fill was most likely cut from the upper portion of your lot prior to mnstruction of your house and graded downslope on the east side of your backyard. Although the , vegetation was dense,we did not observe any evidence to support a deep seated faIlure involving the dense,underlying glacial soils. It appears that the slope failure occurred as a slump in the man-made fill and dces not involve the underlying dense glacial soils. It is possible,based on the slope geometry and the presence of stress cracks behind the scarp that additional sloughing may occur in the fill below the remainder of the intact _. mncrete patio if no rnmediation work is done. " Golder Associafes