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January 3, 2025 <br />HWA Project No. 2021-159-21 <br />Geotechnical Engineering Report 3 HWA GEOSCIENCES INC. <br />Port Gardner Storage Facility <br />were installed to facilitate pump tests to determine parameters the contractors could use for <br />dewatering calculations. The approximate borehole locations are shown on the Site and <br />Exploration Plan, Figure 2. <br />Soil samples were collected within the exploratory borings at approximate 2.5- to 5-foot depth <br />intervals using Standard Penetration Test (SPT) sampling methods, which consisted of using a <br />2-inch-outside-diameter split-spoon sampler driven with a 140-pound auto-hammer. During the <br />test, each sample was obtained by driving the sampler up to 18 inches into the soil with the <br />hammer free-falling 30 inches per stroke. The number of blows required for each 6 inches of <br />penetration was recorded. The standard penetration resistance of the soil was calculated as the <br />number of blows required for the final 12 inches of penetration. If a total of 50 blows was <br />recorded within a single 6-inch interval, the test was terminated, and the blow count was <br />recorded as 50 blows/number of inches of penetration. This resistance provides an indication of <br />the relative density of granular soils and the relative consistency of fine-grained cohesive soils. <br />At the completion of the boreholes, they were backfilled with bentonite chips per Washington <br />State Department of Ecology (Ecology) requirements, except for HWA-10P, HWA-13P, HWA- <br />14P, HWA-16P, HWA-17P-24/HWA-17P-24A, HWA-18P-24, HWA-19P-24 and HWA-20P- <br />24, which were completed as standpipe piezometers. <br />Cone penetrometer testing (CPT) was performed in borings SCPT-1 through SCPT-3 using an <br />electronic cone penetrometer instrument equipped to collect data related to tip resistance, side <br />friction, pore pressure and inclination by ConeTec Inc., under subcontract to HWA. The <br />instrument was advanced into the soil by a hydraulic ram, collecting data every 2 inches. <br />Reported data was provided as both raw data and in a report by ConeTec, Inc, presented in <br />Appendix A. In addition, shear wave velocity testing was conducted every 3.25 feet in borings <br />SCPT-1, SCPT-3, and SCPT-4 simultaneous to collecting CPT data. Shear waves were auto <br />generated by an impact hammer horizontally striking a beam held in place by normal force. <br />Normalized CPT data can be correlated to soil behavior type to determine the subsurface <br />stratigraphy and relative soil densities or consistencies at the boring location. <br />The borings were completed under the full-time observation of an HWA geotechnical engineer <br />or geologist, who collected pertinent information as the exploration was advanced, including soil <br />sample depths, stratigraphy, soil engineering characteristics, and groundwater occurrence. Soils <br />were classified in general accordance with the classification system described on Figure A-1, <br />which also provides a key to the exploration log symbols. The boring logs are presented on <br />Figures A-2 through A-19. Logs for borings conducted as part of the WMVD project (HWA- <br />19P-24 and HWA-20P-24) are presented on Figures A-20 and A-21. <br />The stratigraphic contacts shown on the individual logs represent the approximate boundaries <br />between soil types. Actual soil type transitions may be more gradual. The soil and groundwater