6307 36TH AVE W Geotech Report 2025-07-29

1 1 ' August 13,2008 Project No.T-6241 If grading activities are planned during the wet winter months, or if they are initiated during the summer and extend into fall and winter, the owner should be prepared to import wet weather structural fill. For this purpose, 1 we recommend importing a granular soil which meets the following grading requirements: U.S.Sieve Size Percent Passing 3 inches 100 No.4 75 maximum 1 No.200 5 maximum* *Based on the 3/4-inch fraction. Prior to use,Terra Associates, Inc. should examine and test all materials imported to the site for use as structural fill. We recommend that structural fill be placed in uniform loose Iayers not exceeding 12 inches in thickness and compacted to a minimum of 95 percent of the soil's maximum dry density as determined by American Society for ' Testing and Materials (ASTM) Test Designation D-698 (Standard Proctor). The moisture content of the soil at the time of compaction should be within two percent of its optimum, as determined by this same standard. In nonstructural areas, the degree of compaction may be reduced to 90 percent. All structural fill in City of Everett rights-of-way must conform to City materials and compaction specifications. ' 5.3 Excavations All excavations at the site associated with confined spaces, such as retaining walls and utility trenches, must be ' completed in accordance with local, state, and federal requirements. Based on current Washington Industrial Safety and Health Act(WISHA)regulations, loose to medium dense weathered soils and medium dense to dense outwash soils would be classified as Type C soils. The dense to very dense unweathered till soils would be classified as Type A soils. Accordingly, for temporary excavations less than 20 feet in depth, the side slopes in Type C soils should be laid ' back at an inclination of 1.5:1 (Horizontal:Vertical) or flatter. Excavations less than 20 feet in Type A soils can be laid back at a slope inclination of 0.75:1 or flatter. For temporary excavation slopes less than eight feet in height in Type A soils, the lower 3 '/2 feet can be vertical. All exposed slope faces should be covered with a ' durable reinforced plastic membrane during construction to prevent slope raveling and rutting during periods of precipitation. ' The above information is provided solely for the benefit of the owner and other design consultants, and should not be construed to imply that Terra Associates,Inc. assumes responsibility for job site safety. It is understood that job site safety is the sole responsibility of the project contractor. r Page No. 8 1