501 RIVERSIDE RD REGIONAL DISPOSAL COMPANY EVT TRANSFER FACILITY PHASE 1 SITE IMP Geotech Report 2025-07-28

RDC EVERE TTRANSFER FACILITY_-Everett,Washington APPENDIX A FIELD EXPLORATIONS Subsurface conditions were explored at the site by drilling eight borings (B-1 through B-8). The borings were completed on April 25, 2013 to depths ranging from 111/2 feet to 161 feet below the existing ground surface. The locations of the explorations were surveyed by Reid Middleton I after completion of the field work. The locations of the borings are shown on the Site Plan, Figure 2. Ground surface elevations shown on the exploration logs were estimated based on the existing grade contour lines shown on Figure 2. 1 The borings were completed using a trailer-mounted drill rig with continuous-flight, hollow-stem auger drilling equipment, owned and operated by Geologic Drill Explorations, Inc. of Spokane,Washington. The borings were continuously monitored by a geotechnical engineer from our firm who examined and classified the soils encountered, obtained representative soil samples, observed groundwater conditions, and prepared a detailed log of each boring. 1 The soils encountered in the borings were sampled at 21/2 to 5-foot vertical intervals with a 2-inch outside-diameter, split-barrel standard penetration test (SPT) sampler. The SPT samples were I obtained by driving the sampler 18 inches into the soil with a 140-pound automatic hammer free-falling 30 inches. The number of blows required for each 6 inches of penetration was recorded. The blow count("N-value") of the soil was calculated as the number of blows required for the final 12 inches of penetration. This resistance, or N-value, provides a measure of the relative density of granular soils and the relative consistency of cohesive soils. Where very dense soil conditions preclude driving the full 18 inches,the penetration resistance for the partial penetration was entered on the logs. The blow counts are shown on the boring logs at the respective sample depths. Soils encountered in the borings were visually classified in general accordance with the classification system described in Figure A-1. A key to the boring log symbols is also presented in Figure A-1. The logs of the borings are presented in Figures A-2 through A-9. The boring logs are 111 based on our interpretation of the field and laboratory data and indicate the various types of soils and groundwater conditions encountered. The logs also indicate the depths at which these soils or their characteristics change; although,the change may actually be gradual. If the change occurred between samples, it was interpreted. The densities noted on the boring logs are based on the blow count data obtained in the borings and judgment based on the conditions encountered. Observations of groundwater conditions were made during drilling. Groundwater conditions observed during drilling represent a short term condition and may or may not be representative of �. the long term groundwater conditions at the site. 1 I GEOENGINEERS� June 18,2013 I Page A-1 File No.4322-002.00