3121 TULALIP AVE 2026-02-05 - Laserfiche WebLink

Geotechnical Engineering Evaluation NGA File No.959616 Watson Residence Addition July 6,2016 Everett,Washington Page 3 explorations, examined the soils and geologic conditions encountered, and maintained logs of the explorations. The soils were visually classified in general accordance with the Unified Soil Classification System, presented in Figure 4. The logs of our explorations are presented as Figures 5 and 6. The following paragraph contains a brief description of the subsurface conditions encountered in the explorations. For a detailed description of the subsurface conditions,the hand auger logs should be reviewed. Hand Augers 1 through 3 were located in the general vicinity of the proposed addition areas. At the surface of Hand Augers 1 through 3 we found approximately 0.8-to 1.0-feet of surficial grass and topsoil underlain by approximately 1.0-to 1.7-feet of medium dense to dense, orange brown silty fine to medium sand with gravel that we interpreted as weathered advance outwash soils. Below the weathered advance outwash soils in both of our hand augers, we encountered dense to very dense, brown-gray to gray fine to medium sand with silt and gravel that we interpreted as native unweathered advance outwash soils. Hand Augers 1 through 3 were completed within the native Advanced. Outwash soils at respective depths of approximately 6.5, 6.0, and 5.5 feet below the existing ground surface. Hand Augers 4 through 7 were located within the steep slope area. At the surface of Hand Auger 4, we encountered approximately 3.5-feet of very loose to loose, dark brown silty fine to medium sand with gravel, debris, and organics, which we interpreted as undocumented fill soils. Underlying the undocumented fill soils, we encountered approximately 1.0 foot of medium dense, orange brown, silty fine to medium sand with gravel underlain by dense to very dense brown gray to gray fine to medium sand with silt and gravel, which we interpreted as weathered unweathered native advance outwash soils, respectively. At the surface of Hand Augers 5 through 7 we found approximately 0.8 feet of surficial topsoil underlain by dense, brown-gray fine to medium sand with silt and gravel that we interpreted as native unweathered native advance outwash soils. Hand Augers 4 through 7 were terminated within the native unweathered advance outwash soils at depths in the range of 1.5 to 5.5 feet below the existing ground surface. Hydrologic Conditions We did not encounter groundwater within our explorations or observe groundwater seepage emitting from.the slope. However, we anticipate that perched water conditions may develop on this site during extended periods of wet weather. Perched water occurs when surface water infiltrates through less NELSON GEOTECHNICAL ASSOCIATES, INC.