4704 HARBOR LN 2018-01-02 MF Import

Main Office 17311 — 135" Avenue NE, A-500 Woodinville, WA 98072 (425) 486.1669 FAX (425) 481-2510 (425) 337-1669 Snohomish County DATE: October 6, 2009 NELSON GEOTECHNICAL ASSOCIATES, INC. GEOTECHNICAL ENGINEERS & GEOLOGISTS Engineering -Geology Branch 437 East Penny Road Wenatchee, WA 98801 (509) 666.7696 FAX (509) 665-7692 MEMORANDUM TO: Rick and Holly Ar derson CC: John Dippold — Carney Badley Spellman Eilom Mattes — Penlco Insurance FROM: Khaled M. Shawish, PE Bala Dodoye-Alali RE: Anderson Landslide Repairs Temporary Erosion Control 4704 Harbor I ann. Everett, Washington NGA File No. 816909 We recommend that temporary erosion control measures be promptly implemented on the exposed landslide scarp on the Anderson's portion of the slide. The area is currently exposed and could experience additional movement if not protected. We recommend that the exposed scarp be covered with erosion control matting, as shown on the Temporary Erosion Control Details on the attached two figures. The matting should be composed of strong synthetic material and should be porous. The CONTECH TRM C45 erosion control matting, or approved equivalent, should be appropriate for this application. Your landscape contractor may propose an alternative matting, however we should review and approve any proposed alternatives prior to installation. The platting should be thoroughly staked to the ground surface using 3-foot long metal stakes. The matting should extend from the top of the slope, down to the property line, and should cover the width of the slide scarp. Some removal ni vegetation and/or loose material may be needed to ensure intimate contact between the erosion control material and the slope. The above recommended system should provide adequate temporary protection for the slope against nonual erosion stenhming from direct rainfall. The erosion control matting should not increase runoff I/�