Aspect Consulting LLC 11/30/2020

City of Everett,Public Works Operations November 13, 2020 Project No. 200505 For each test pit we will record and document the following, at a minimum: • Conditions in which test pitting is performed • Dimensions and approximate location of each test pit • Lithology observed with each test pit • Locations of features and collected samples,if any The schedule for the excavations will be coordinated with you and based on the availability of your personnel and equipment required to excavate the test pits to a depth up to 12 feet below existing surface grades. Each test pit will be directly observed and logged by one of Aspect's engineers or geologists. Backfill of the test pits will be performed by City personnel, using high quality(clean, freely draining, and angular) crushed gravel or quarry rock chips from a City stockpile(s). Material removed from the stockpiles will be placed within the landfill by the City and managed consistent with current practices. Sampling of soils encountered during the excavations may be performed in lieu of the sampling outlined in Task 3, as determined by Aspect personnel overseeing the test pit excavation. Based on the results of the field explorations and laboratory testing completed in Task 3 below, Aspect will complete geotechnical engineering evaluations of berm and global slope stability, considering both existing conditions and anticipated long-term changes in site topography as the landfill continues to be filled. As part of this analysis we will review the need for modification, rebuilding, or reconstruction of the berm to support long term stability, consistent with the City's anticipated life of the facility. The deliverable from this task will be a memo summarizing the test pit results,our geotechnical engineering evaluations, and our conclusions regarding current and future berm stability, and recommendations for berm modifications,if necessary. As needed, Aspect will prepare updates to the appropriate sections of the operational plans to reflect the findings of this task. Task 3 - Soil Sampling and Geotechnical Laboratory Testing To assess stability of the dredged backwash solids disposed within the landfill, we will collect five bulk(5-gallon bucket)samples of material for geotechnical laboratory testing. The samples will be analyzed for using the following standard test methods, or using an approved alternative: • ASTM D422—Particle Size Analysis with Hydrometer • ASTM D1557—Laboratory Compaction using Modified Effort • ASTM D4318—Liquid Limit, Plastic Limit, and Plasticity Index of Soils • ASTM D2850—Unconsolidated-Undrained Triaxial Shear Strength Results of the analyses will be used to perform stability analysis of the Landfill slopes and the lake- side berm and will inform any updates to the operational plans performed in subsequent tasks. Laboratory test results will be included with the memo described in Task 2 above. Page 3