7100 HARDESON RD Geotech Report 2025-03-06

Geotechnical Engineering Report lierracon Merrill Creek Operations Base Expansion • Everett, Washington December 14, 2020 • Terracon Project No. 81205012 GeoReport EXPLORATION AND TESTING PROCEDURES 1 Field Exploration Boring Boring Depth Location B-1-20 26'/2 feet North-central portion of expansion area B-2-20 41'/2 feet South-central portion of expansion area Boring Layout and Elevations: Unless otherwise noted, Terracon personnel provided the boring 1 layout using taped measurement to existing site features. Coordinates were obtained with reference to taped features and their relative positions as shown on ortho-corrected aerial photography and internal Terracon GIS software. Elevations were not obtained. If elevations and a more precise boring layout are desired, we recommend borings be surveyed following completion of fieldwork. Subsurface Exploration Procedures: We advanced the borings with a truck-mounted rotary drill rig using continuous-flight, hollow-stem augers. The driller cored through the existing concrete pavement with a diamond core-barrel, then switched to auger drilling of soil. Six samples were obtained in the upper 15 feet of each boring and at intervals of 5 feet thereafter. In the split-barrel sampling procedure, a standard 2-inch outer diameter split-barrel sampling spoon was driven into the ground by a 140-pound automatic hammer falling a distance of 30 inches. The number of blows required to advance the sampling spoon the last 12 inches of a normal 18-inch penetration is recorded as the Standard Penetration Test(SPT) resistance value. The SPT resistance values, also referred to as N-values, are indicated on the boring logs at the test depths. We observed and recorded groundwater levels during drilling and sampling. For safety purposes and in accordance with Washington State regulations, all borings were backfilled with granular bentonite clay chips after their completion. The concrete pavement surface was then restored with a concrete patch. The sampling depths, penetration distances, and other sampling information was recorded on the field boring logs. The samples were placed in appropriate containers and taken to our soil laboratory for testing and classification by the Geotechnical Engineer. Our exploration team prepared field boring logs as part of the drilling operations. These field logs included visual classifications of the materials encountered during drilling and our interpretation of the subsurface conditions between samples. Final boring logs were prepared from the field logs. The final boring logs represent the Geotechnical Engineer's interpretation of the field logs and include modifications based on observations and tests of the samples in our laboratory. Laboratory Testing The project engineer reviewed the field data and assigned a limited number of laboratory tests to understand the engineering properties of the various soil strata, as necessary, for this project. Responsive • Resourceful • Reliable EXPLORATION AND TESTING PROCEDURES 1 of 2