3815_PGSF WMVD Pkg 2_Vol 4-3_03.03.2026_BXWA_Certified

3rd Interim Action Construction Report Kimberly-Clark Upland Site 0121049.080.084 July 30, 2024 2-2 landauinc.com 2.2 Site Grading Site grading conducted during implementation of the Interim Action included importing, grading, and compacting clean fill to meet the following goals: 1) increase elevation of the Site to be protective of anticipated sea level rise associated with expected climate change impacts, 2) direct stormwater drainage to the site-wide stormwater conveyance and treatment system, and 3) support construction of the low-permeability cap described in Section 2.3 to reduce surface water infiltration. Final site grades are presented on as-built sheets C3.3 through C3.14 (Appendix A). Clean fill was compacted to meet subgrade design requirements for the low-permeability cap. A preload was also used at the Site to further limit long-term settlement in areas with significant wood debris deposits and protect the long-term functionality of the low-permeability cap. 2.2.1 Preload and Grading Preload activities were conducted in accordance with the Preload Early Action Letter, which was included as an attachment to the Work Plan. Preload material was imported to the Site, placed in preload within the area illustrated on as-built sheet C1.1 (Appendix A). Following completion of preloading, the material was used as fill during Site grading activities. Preload material was evaluated against import fill criteria presented in the Work Plan prior to being transported on Site, as is detailed in Section 2.2.2 below. Results of preloading activities are presented in the Preload Ground Improvement Summary Memorandum (Appendix B). Performance of the preload was monitored from August 2021 through the completion of settlement associated with the preload in January 2022. Following completion of preloading activities, preload soil was used to provide the base course for the pavement cap and raise the elevation of the Upland Area. This material was graded and compacted to meet geotechnical requirements, reduce stormwater infiltration, and convey stormwater to stormwater treatment infrastructure installed as a part of the Project. 2.2.2 Import Fill Evaluations In accordance with the Work Plan, import fill evaluations were conducted by the contractor and submitted to the Port and Ecology for review and approval prior to delivering the material to the Site. Fill materials imported to the Site were sampled at a rate of five samples for the first 1,000 cubic yards (CY) and one sample per each additional 1,000 CY of each specific material. Characterization samples were analyzed for the following: • Gasoline-range total petroleum hydrocarbons (TPH-G) by Northwest total petroleum hydrocarbon gasoline-range extended (NWTPH-Gx) and Northwest total petroleum hydrocarbon diesel-range extended (NWPTH-Dx) • Polycyclic aromatic hydrocarbons (PAHs) by US Environmental Protection Agency (EPA) Method 8270 selected ion monitoring (SIM) • Metals (arsenic, copper, lead, mercury, nickel, zinc) by EPA Method 6000/7000