7505 SEAWAY BLVD Geotech Report 2022-10-25

November 11, 2016 HWA Project No. 2014-117-21 2.1 HWA PHASE I EXPLORATIONS Our Phase I exploration program consisted of drilling four geotechnical borings, designated BH-1 through BH-4, at various locations on the subject property. Phase I explorations were conducted by Holocene Drilling of Lacey, Washington on August 15th 2014. Boring BH-1 was drilled to a depth of 20.8 feet in support of design of the proposed bus bay platforms. Boring BH-2 was drilled to a depth of 20.5 feet in support of developing soil parameters for design of site improvements. Boring BH-3 was drilled to a depth of 21 feet in support of stormwater facility design. Boring BH-4 was drilled to a depth of 20.9 feet in support of design of the center bus island. 2.2 HWA PHASE II EXPLORATIONS Our Phase II exploration program consisted of drilling two machine-drilled borings (designated BH-5 and BH-6) and advancing five hand borings (designated HH-1 through HH-5). Dynamic cone penetrometer(DCP)testing was performed in each hand boring to evaluate soil density at depths beyond the bottom of the hand-bored shaft. Borings BH-5 and BH-6 were drilled to depths ranging of 31.5 and 30.6 feet, respectively, in support of proposed signal poles near the proposed transit center entrance on 75th Street SW. Borings BH-5 and BH-6 were drilled by Environmental Drilling of Snohomish, Washington on February 15, 2016 and November 3, 2016, respectively. Hand borings HH-1 and HH-2 were advanced to depths of 2.3 and 3 feet, respectively, in support of the proposed bus bay platforms. Hand borings HH-3 and HH-4 were advanced to depths of 3.5 and 3.3 feet, respectively, in support of a proposed retaining wall. Hand boring HH-5 was advanced to a depth of 3 feet in support of proposed signal pole design near the current entrance to the PUD facility on'75th Street SW. The approximate boring locations for Phase I and H explorations are shown on the Site and Exploration Plan, Figure 2. Each exploration was monitored by an HWA geotechnical engineer. Summary boring logs are presented in Appendix A, Figures A-2 through A-12. 3. SITE CONDITIONS 3.1 GENERAL GEOLOGIC CONDITIONS Geologic information for the project area was obtained from the Preliminary Surficial Geologic Map of the Mukilteo and Everett Quadrangles, Snohomish County, Washington (Smith, 1976). According to this map, near-surface deposits at the project site consist of Vashon glacial till. Glacial till is the material which was deposited along the sole of the glacial ice as lodgement till. 2014-117 Final Geotechnical Report 3 HWA GEOSCIENCES INC.