1209 MADRONA AVE 2016-10-05 - Laserfiche WebLink

Geotechnical Engineering Evaluation Packer Property Retaining Walls and Steep Slope Evaluation Everett, Washington INTRODUCTION This report presents the results of our geotechnical engineering investigation and evaluation of the existing block retaining walls and steep slopes at the Packer property in Everett,Washington. The project site is located at 1209 Madrona Avenue, as shown on the Vicinity Map in Figure 1. The purpose of this study is to explore and characterize the site's surface and subsurface conditions, and to provide geotechnical recommendations for improving the conditions of the existing walls and stabilization of the landslide that recently occurred on the steep slopes within the northern portion of the property. The property is currently occupied by a single-family residence within the southern portion of the site. A steep northwest-facing slope is located to the north of the residence. The portion of the steep slope along the western property line appears to be an old ravine area. The neighboring property to the west slopes steeply down to your western property line and appears to share the steep slope area within the old ravine. There is a total of five tiers of short concrete block walls existing on the steep slope below the residence. We understand that the property owner began constructing the lower western block wall along the steep slope immediately above the old ravine area in the summer of 2000. The upper three walls were then constructed during 2001 to 2003. The lower eastern wall was then constructed in 2005 after a landslide occurred below the lower western wall. In general, these walls appear to be relatively stable and appear to have experienced minimal movement throughout the years since they were constructed. We also understand that in late November 2012, two landslides occurred over a 24 hour period. The first slide involved the lower (down-ravine) portion of the steep neighboring slope to the west and an area on the Packer property directly adjacent to the neighbor's landslide area, but lower in elevation. The slide area on the Packer property extended up-ravine to about fifteen feet below the lower western retaining wall. The second slide involved the upper(further up the ravine)portion of the steep neighboring slope to the west. Also involved was an area of the Packer property directly adjacent to the neighbor's new landslide area,but lower in elevation. The new slide area on the Packer property became within five feet below the lower western retaining wall. Prior vegetation that was planted on the slope by the homeowners were mostly removed by the recent slides. NELSON GEOTECHNICAL ASSOCIATES, INC.