4937 SEA BREEZE WAY 2018-01-02 MF Import

Page 5 Mr. and Mrs. Darrel Freudenburg sand with traces of organic matter to very fine sandy silt. The fill depth varies from zero near the Powder Mill Gulch Creek to a depth of about 9 to 10 feet in the area adjacent to the driveway of the home. The layer beneath the fill consists of a hard clay. Subsurface water cannot penetrate the hard clay layer. BOE/IVG Instead, the water tends to perch on top of the impermeable clay and flow towards the creek. These existing geologic conditions are extremely conducive to earth sliding. The report concludes that potential contributory causes of earth sliding are as follows: 1. The placement of fill material on the property acts to load the weak soils and accelerate the earth movement. 2. The small log dam in Powder Mill Gulch Creek createe: a plunge pool downstreaw that can deepen and widen with increasing stream flows. During plunge pool formation, the hard clay layer will erode at the toe of the slope. The loss of material at the toe of the slope reduces resisting forces, increasing the risk of sliding. 3. The overlying silty sand layer is significantly more erodible than the hard clay below, and its erosicn can cause more rapid earth sliding. This condition can occur if peak water levels in the stream exceed the elevation of the top of the clay layer. 3. Conclusions These reports cover a period of 25 years. certain conclusions consistently arise and when the reports are read together, several facts are evident: 1. The property has a long history of instability and earth slides caused by the existing geologic and hydrogeologic conditions of the soil. 2. Subsurface water cannot penetrate the hard clay layer underlying the property. Therefore, the subsurface water flows downhill towards the creek along the interface between the clay any: