11625 AIRPORT RD SONRISE CHRISTIAN CENTER Geotech Report 2022-10-25

I I GEOTECHNICAL EVALUATION EVERETT,WASHINGTON February 6,2018 4.o Field Investigation 4.1.1 Site Investigation Program The geotechnical field investigation program was completed on January 23,2018 and included excavating and sampling four test pits within the property. The soils encountered were logged in the field and are described in accordance with the Unified Soil Classification System(USCS). A Cobalt Geosciences field representative conducted the explorations, classified the encountered soils, kept a detailed log of each test pit,and observed and recorded pertinent site features. The results of the test pit explorations and sieve analyses are presented in Appendix C. 5.0 Soil and Groundwater Conditions I 5.1.i Area Geology The site lies within the Puget Lowland. The lowland is part of a regional north-south trending trough that extends from southwestern British Columbia to near Eugene, Oregon. North of Olympia, Washington, this lowland is glacially carved, with a depositional and erosional history including at least four separate glacial advances/retreats. The Puget Lowland is bounded to the west by the Olympic Mountains and to the east by the Cascade Range. The lowland is filled with glacial and non-glacial sediments consisting of interbedded gravel,sand,silt,till,and peat lenses. The Geologic Map of the Everett Quadrangle,indicates that the site is underlain by Vashon Glacial Till. Vashon Glacial Till is typically characterized by an unsorted, non-stratified mixture of clay, silt, sand, gravel, cobbles and boulders in variable quantities. These materials are typically dense and relatively impermeable. The poor sorting reflects the mixing of the materials as these sediments were overridden and incorporated by the glacial ice. Test Pits TP-i through TP-4 All of the test pits encountered approximately io to 12 inches of topsoil and vegetation underlain by approximately i to 3 feet of loose to medium dense, silty-fine to medium grained sand with gravel (Weathered Glacial Till). This layer was underlain by dense to very dense, silty-fine to medium grained sand with gravel(Glacial Till),which continued to the termination depth of the test pits. 5.1.2 Groundwater Light to heavy groundwater seepage was encountered in TP-i at 3 feet below grade,in TP-2 at 2 feet below grade,and in TP-4 at 2 feet below grade. Groundwater was not encountered in TP-3. The groundwater is perched between weathered and unweathered glacial till and is not likely present at the site during the dry season(generally June through September). 2 PO Box 82243 Kenmore,WA 98028 (206)331-1097 Cobaltgeo@ gmail.com