4730 COLBY AVE YMCA Geotech Report 2025-04-14

Subsurface Exploration, Geologic Hazard,and Snohomish County YMCA Geotechnical Engineering.Report Everett, Washington Design Recommendations should extend horizontally outward a minimum distance of 3 feet beyond the locations of the perimeter footings or roadway edges before sloping down at a maximum angle of 2H:1V. The contractor should note that any proposed fill soils should be evaluated by AESI prior to their use in fills. This would require that we have a sample of the material at least 72 hours in advance 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. The existing fill, lodgement till, and pre-Fraser soils are estimated to contain substantially more than 5 percent fine-grained material. Use of moisture-sensitive soil in structural fills should be limited to favorable dry weather and dry subgrade conditions. Construction equipment traversing the site when the soils are wet can cause considerable disturbance. If fill is placed during wet weather or if proper compaction cannot be obtained, 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 25 percent retained on the No. 4 sieve. A representative from our firm should inspect the stripped subgrade and be present during placement of structural fill to observe the work and perform a representative number of in-place density tests. In this way, the adequacy of the earthwork may be evaluated as filling progresses, and any problem areas may be corrected at that time. It is important to understand that taking random compaction tests on a part-time basis will not assure uniformity or acceptable performance of a fill. As such, we are available to aid the Client in developing a suitable monitoring and testing program. 11.0 FOUNDATIONS Conventional spread footings and column pads may be used for building support when founded either directly on the undisturbed, dense to very dense natural sediments or on new Structural Fill placed above suitable native deposits, as previously discussed. We recommend that an allowable foundation soil bearing pressure of 4,000 pounds per square foot (psf) be utilized for design purposes, including both dead and live loads. Foundation areas should be deepened, if necessary, to expose sediments suitable for the support of the recommended bearing pressures. An increase of one-third may be used for short-term wind or seismic loading. All footings must penetrate to the prescribed bearing stratum and no footing should be founded in or above loose, organic, or fill soils. February 26,2018 ASSOCIATED EARTH SCIENCES,INC. AWR/ms-170671E001-2-Projects12 01 706 71 1KE\WP Page 13