10930 HOLLY DR Geotech Report 2025-08-08

Helix Design Group,Inc.-Greenwood Heating Sr Air Conditioning,Everett,WA April 22,2022 Geotechnical Engineering Report Z0219 The enclosed test pit logs indicate the vertical sequence of soils and materials encountered in our test pits,based on our field classifications. Where a soil contact was observed to be gradational or undulating, our logs indicate the average contact depth. We estimated the relative density and consistency of the in-situ soils by means of the excavation characteristics and the stability of the test pit sidewalls. Our logs also indicate the approximate depths of any sidewall caving or groundwater seepage observed in the test pits. The soils were classified visually in general accordance with the system described in Figure A-1,which includes a key to the exploration logs. Summary logs of the explorations are included as Figures A-2 through A-4. 3.0 SITE CONDITIONS The following sections present our observations, measurements, findings, and interpretations regarding surface, soil, groundwater,infiltration and seismic conditions. 3.1 Surface Conditions As previously indicated, the project site consists of two contiguous, previously undeveloped tax parcels, situated immediately northeast of the intersection between Airport Rd and Holly Dr, towards the southwest corner of the city limits of Everett, Washington. The associated parcels occupy 1.34 acres and 0.85 acres,respectively,with the subject property encompassing a total areal extent of approximately 2.19 acres,with the entirety of the property being enclosed by chain-link fencing. The project area is bordered by developed commercial/industrial sites immediately to the north and east,with these areas currently being occupied by Pioneer Cable Contractors,Inc., and Goldfinch Bros,Inc.,respectively. Additionally,offsite to the west,beyond the course of Airport Rd,is the Airport Road Recycling&Transfer Station, and a transformer station for a local electric utility. Beyond(to the west)the transfer and transformer stations are properties owned by Paine Field. Currently the site is occupied by tall grasses,thin trees and scattered brushes. Brush and thin trees are largely relegated to the margins of the property,with the interior of the site containing only thin. ground cover. The interior of the site has also recently been impacted by manmade activities,with evidence of recent homeless encampments being present. Topographically, the project area is relatively level to gently sloped, with a slight descent from south to north being observed over the full extent of the parcel. 3.2 Soil Conditions Our subsurface explorations revealed relatively consistent subgrade conditions across the project area;generally consisting of a surface mantle of forest duff underlain by native,glacial till deposits. The uppermost 2 to 21/2 feet of glacial soils were highly weathered, comprising mottled,medium dense gravelly silty sand. Beneath this soil horizon we encountered unweathered glacial till soils, generally comprising very dense gravelly silty sand. Unweathered glacial till soils were observed through the termination of all of our test pit explorations; a maximum depth of approximately 5 feet below existing grade, Migizi Group,Inc. Page 3 of 16