3500 TERMINAL AVE Geotech Report 2022-10-25

30 I Port of Everett—South Terminal Wharf& Electrical Upgrades—Phase 2 • For earthwork in the vicinity of the existing bulkhead wall,we recommend placing fill and compacting using light compaction equipment. • Compact all structural fill to at least 95 percent of the modified Proctor maximum dry density(as determined by ASTM D 1557 test procedure). • Control the moisture content of the fill to within 2 percent of the optimum moisture.Optimum moisture is the moisture content corresponding to the maximum Proctor dry density. • In wet subgrade areas,clean material with a gravel content of at least 30 to 35 percent may be necessary.Gravel is material coarser than a US No.4 sieve. • At least one week before filling begins, provide samples of the structural and drainage fill for laboratory testing. Laboratory testing will include a Proctor test and gradation for structural fill and a gradation for drainage fill. Field testing with a nuclear density gauge uses the maximum dry density determined from a Proctor test,therefore it is important to complete the laboratory testing as soon as possible in order to not delay backfilling. Use of On-Site Soil as Structural Fill Our explorations indicated that the near-surface dredge fill includes silty,gravelly sand,and sandy gravel, and are likely suitable to be used for structural fill.The suitability of excavated site soils for use as compacted structural fill depends on the gradation and moisture content of the soil when it is placed.As the amount of fines(that portion passing the No.200 sieve)increases,the soil becomes increasingly sensitive to small changes in moisture content and adequate compaction becomes more difficult to achieve.Soil containing more than about 5 percent fines cannot be consistently compacted to a dense non-yielding condition when the water content is greater than about 2 percent above or below optimum. Reusable soil must also be free of organic and other compressible material. In general, on-site soils used as structural fill should conform to Section 9-03.14(3)of the 2016 WSDOT Standard Specifications(M 41-10) with the exception that the percentage passing the U.S. No. 200 sieve should be based on the minus%- inch fraction. Option 3 should not be allowed. Temporary Cuts Because of the variables involved,actual slope grades required for stability in temporary cut areas can only be estimated before construction.We recommend that stability of the temporary slopes used for construction be the sole responsibility of the contractor,since the contractor is in control of the construction operation and is continuously at the site to observe the nature and condition of the subsurface. Excavations should be made in accordance with all local,state,and federal safety requirements. For planning purposes,the soils across the site are likely OSHA Soil Classification Type C; however,the soil classification must be reevaluated at the time of construction. The stability and safety of open trenches and cut slopes depend on a number of factors, including: 19232-01 N December 6,2017 H RTCROWSER