1920 GRAND AVE Geotech Report 2022-10-25

Mr. Bill Messner ES-6132 October 5, 2018 Page 2 Project Description The site is occupied by a single-family residence, driveway (shared with the adjacent lot to the south), landscaping features, and related improvements. We understand the westerly slope, which is comprised largely of advance outwash and transitional beds, has sloughed and/or eroded in places. To stabilize the slope, a solider pile wall and grouted tieback anchors will be installed generally to the west of the driveway and existing concrete wall, with the tieback anchors extending east into the slope. Piles were installed to support the existing concrete wall; as such, dead load is transferred to the dense native soils at depth, and the existing concrete wall will not surcharge the proposed soldier pile wall. If the design assumptions outlined in this section are incorrect or change, or if construction conditions differ from those encountered during our fieldwork, ESNW should be contacted to review the recommendations and conclusions provided in this letter. This letter has been prepared for the exclusive use of Mr. Bill Messner and his representatives. No warranty, expressed or implied, is made. This letter was prepared in a manner consistent with the level of care and skill that is typical of other members in the profession currently practicing under similar conditions in this area. Site Conditions The subject site is located approximately 150 feet north of the intersection between 20th Street and Grand Avenue, in Everett, Washington. The approximate location of the property is depicted on Plate 1 (Vicinity Map). The property is comprised of one tax parcel (Snohomish County Parcel No. 004374-372-027-01) totaling approximately 0.38 acres. The site is surrounded to the north and south by single-family residences, to the east by Grand Avenue, and to the west by a railroad right-of-way and West Marine View Drive. Site topography is relatively level within developed portions of the property but descends sharply to the west thereafter. We estimate total site elevation change is about 70 to 80 feet, and slope gradients are roughly 80 to 90 percent. Slope vegetation is primarily trees and brush. Subsurface Conditions An ECI representative observed, logged, and sampled three borings on November 10, 2000. Two borings (B-2 and B-3) were advanced along Grand Avenue, and one boring (B-1) was advanced near the center of the existing residence, nearest the slope. The approximate locations of the borings are depicted on Plate 2 (Boring Location Plan). The subsurface information in this section is intended as a general summary concerning the slope; please refer to the attached boring logs for a more detailed description of subsurface conditions. At B-1, loose to very dense silty sand was reported to a depth of about nine feet below the existing ground surface (bgs). Hard, fat clay was encountered thereafter to about 16.5 feet bgs, transitioning to sands with variable silt content until about 33.5 feet bgs. Interbedded, very dense silt and poorly graded sand, as well as hard clay, was encountered to the boring terminus at roughly 41 feet bgs. Earth Solutions NW,LLC