4704 HARBOR LN 2018-01-02 MF Import

Fram 10/30/2009 12 30 #230 P.003/003 Anderson Landslide Repairs Temporary Erosion Control Summary Everett, Washington October 30, 2009 NGA File No. 816909 Page 2 The contractors also detennined that the downspouts and drains for the house are dirvcted to a single black cotugated pipe that had lxsn connected to the black IIDPE pipe that tuns down the slope. This connection was severed due to the slide. Based on that finding, and since the corrugated pipe cannot be re -attached to the black I IDPF pipe at this time due to objections from die downhill property owners, we recommended that the comrgated pipe be bent and placed horizontally across the slope to the cast of the landslide and that a perforated pipe be placed at the end of the pipe to help disperse runoff. We observed that the contractor added a black perforated pipe covered with a black sleeve and laid the pipe across the top of the slope. '11is will act as a temporary area to disperse the water until the shoring wall is installed. As mentioned in our previous memo, the erosion control matting should provide adequate temporary protection for the slope against normal erosion stemming from direct rautfall. The erosion control matting should not increase runoff onto downhill properties. In fact, runoff coming off of the scarp should be reduced, as the erosion control material will reduce the velocity of runoff and allow more trttiltration/evaporation of rain water. Some maintenance of this system will likely be needed during and alter heavy rain events. We emphasize that this is not a permanent slope stabilization measure. The shoring wall along with erosion control and drainage improvements as recommended in our geotechnical report should be implemented as soon as possible. We trust this memorandum should satisfy your needs at this time. Please contact us if you have any questions or require additional services. NELSON GEOTECHNICAL ASSOCIATES, INCJib A