2721 WETMORE AVE MARQUEE APARTMENTS Geotech Report 2023-06-22

Subsurface Exploration, Geologic Hazard,and 2721 Wetmore Preliminary Geotechnical Engineering Report Everett, Washington Preliminary Design Recommendations to 4 to 6 feet are expected. As is typical with earthwork operations, some sloughing and raveling may occur, and cut slopes may have to be adjusted in the field. In addition, WISHA/OSHA regulations should be followed at all times. 9.0 STRUCTURAL FILL Should structural fill be necessary to establish desired grades beneath lightly-loaded portions of the project (floors, etc.), it should be placed and compacted according to the recommendations presented in this section. Due to the expected high foundation bearing loads, compacted structural fill should not be placed beneath building footings or columns. However, up to 1 foot of controlled density fill (CDF) can be used to protect footing excavations in the moisture-sensitive lodgement till. Structural fill may also be required for sidewalk and ramp subgrades and for backfill around foundation elements. All references to structural fill in this report refer to subgrade preparation, fill type, placement, and compaction of materials, as discussed in this section. If a percentage of compaction is specified under another section of this report, the value given in that section should be used. Structural fill is defined as non-organic soil, acceptable to the geotechnical engineer, placed in maximum 8-inch loose lifts, with each lift being compacted to at least 95 percent of the modified Proctor maximum dry density using ASTM D-1557 as the standard. In the case of roadway and utility trench filling, the backfill should be placed and compacted in accordance with City of Everett standards. For planning purposes, we recommend the use of Type 17 sand and gravel for right-of-way and utility trench backfill. The use of CDF, approved by the City, can also be used for trench backfill. The contractor should note that AESI should evaluate any proposed fill soils prior to their use in fills. This would require that we have a sample of the material at least 3 business days in advance of filling activities to perform a Proctor test and determine its field compaction standard. Soils in which the amount of fine-grained material (smaller than the No. 200 sieve) is greater than approximately 5 percent (measured on the minus No. 4 sieve size) should be considered moisture-sensitive. Use of moisture-sensitive soil in structural fills is not recommended. The on-site soils are not considered suitable for use as structural fill. In addition, construction equipment traversing the site when the soils are wet can cause considerable disturbance. For all fills, a select import material consisting of a clean, free-draining gravel and/or sand should be used. Free-draining fill consists of non-organic soil with the amount of fine-grained material limited to 5 percent by weight when measured on the minus No. 4 sieve fraction and at least 30 percent retained on the No. 4 sieve. Neither the native sediments nor local imported fill soils should be reactive with normal cements. May 28,2019 ASSOCIATED EARTH SCIENCES,INC. FSM/Id-190168E001-2-Projects\20190168\KE\WP Page 9