8417 EVERGREEN WAY Geotech Report 2022-10-25

Geotechnical Engineering Report-Revised 11-erracon Proposed CFT Retail al Everett,Washington February 1, 2018■Terracon Project No. 81185002 Field Exploration Description The proposed boring locations were laid out in the field by a Terracon representative using a scaled site plan provided by the client. Several locations were adjusted due to close proximity to overhead powerlines and underground utility lines. Ground surface elevations indicated on the boring logs were estimated from Google Earth Imagery. The locations and elevations of the borings should be considered accurate only to the degree implied by the means and methods used to define them. The eight (8) soil borings were drilled using a truck-mounted B-61 drill rig using hollow-stem augers to advance the boreholes. Samples of the soil encountered in the borings were obtained using the split-barrel sampling procedures. In the split-barrel sampling procedure, the number of blows required to advance a standard 2-inch O.D. split-barrel sampler the last 12 inches of the typical total 18-inch penetration by means of a 140-pound hammer with a free fall of 30 inches, is the standard penetration resistance value (SPT-N). This value is used to estimate the in situ relative density of cohesionless soils and consistency of cohesive soils. An automatic SPT hammer (autohammer) was used to advance the split-barrel sampler in the borings performed on this site. A significantly greater efficiency is achieved with the autohammer compared to the conventional safety hammer operated with a cathead and rope. This higher efficiency has an appreciable effect on the SPT-N value.The effect of the autohammer's efficiency has been considered in the interpretation and analysis of the subsurface information for this report. The autohammer efficiency was reported by the subcontract driller as 75%. The samples were tagged for identification, sealed to reduce moisture loss, and taken to our laboratory for further examination, testing, and classification. Information provided on the boring logs attached to this report includes soil descriptions, consistency evaluations, boring depths, sampling intervals, and groundwater conditions. The borings were backfilled with bentonite chips and sealed with black cement prior to the drill crew leaving the site. A field log of each boring was prepared by a Terracon geotechnical engineer or geologist. These logs included visual classifications of the materials encountered during drilling as well as the engineer's geologist's interpretation of the subsurface conditions between samples. Final boring logs included with this report represent the engineer's interpretation of the field logs and include modifications based on laboratory observation and tests of the samples. Responsive ■ Resourceful ■Reliable Exhibit A-3