4730 COLBY AVE SEPA 016 - 027 - YMCA Geotech Report 2025-04-14

7 7 October 25. 2015 YMCA - Everett L&A Job No. 15-089 Page 5 Soil Condition Subsurface conditions of the subject project site were explored with eleven test pits. These test pits were excavated on September 4, 2015, with a rubber-track backhoe to depths of 9.5 to 12.0 feet. The approximate locations of the test pits are shown on Plate 2 Site and Exploration Location Plan. The test pits were located with either a tape measure or by visual reference to existing topographic features in the field and on the topographic survey map, and their locations should be considered only as accurate to the measuring method used. A geotechnical engineer from our office was present during subsurface exploration, examined the soil and geologic conditions encountered, and completed logs of test pits. Soil samples obtained from each soil layer in the test pits were visually classified in general accordance with United Soil Classification System, a copy of which is presented on Plate 4. Detailed descriptions of soils encountered during site exploration are presented in test pit logs on Plates 5 through 9. Fill was encountered by all test pits except Test Pit 6, located in the middle of the open field north of the existing buildings, in which a thin layer of topsoil was encountered on the surface. The fill is from a few inches up to 5.0 feet in total thickness. Except the top few inches, the fill, consisting of light-brown to light-gray, medium-dense, silty to slightly-silty, fine to medium sand with various amounts of gravel, appears to have been compacted to a medium-dense state. A layer or layers of weathered soil of light-brown to brown to brown- gray, medium-dense, silty fine sand with trace gravel from 1.0 to 4.3 feet or more thick, was found underlying the fill and/or relic topsoil. An advance outwash deposit of light-gray, LIU & ASSOCIATES, INC.