2802 HOYT AVE EVERETT ELKS Geotech Report 2018-01-02 MF Import

Geotechnical-Engineering Evaluation Everett Elks Club November 2, 2006 NGA File No. 751106 Page 4 approximately two feet of silty fine to medium sand inter-pretcd to be fill, we encountered approximately 12 feet of dense to very dense, orange -brown grading to brown -gray, fine to medium sand with gravel and trace silt. Below the sand, we encountered approximately five feet of very dense, brown -gray, silty fine n to medium sand underlain by fine to medium sand with varying amounts of silt. Boring 2 was terminated in the native sand with gravel at a depth of approximately 35.5 feet. Boring 3 was drilled within the alley along the western side of the existing building. Below the concrete in Boring 3, we also encountered approximately two feet of medium dense, silty fine to medium sand interpreted to be fill. 111e fill was underlain by eery dense, gray silty fine to medium sand. Boring 3 was terminated in the silty sand at a depth of approximately 15.5 feet. Hydrologic Conditions Wet conditions were encountered in the fill material directly under the sidewalks and alley, but groundwater seepage was not encountered within the explorations. A perched groundwater condition may develop on this site dining the wet season. Perched water occurs when surface water infiltrates through less dense, more permeable soils such as the sand and gravel and accumulates on top of a relatively impermeable material such as the underlying silty material. Perched water does not represent a regional groundwater "table" within the upper soil horizons. Perched water tends to vary spatially and is dependent upon the amount of rainfall. We would expect the amount of any groundwater to decrease during drier times of the year and increase during wetter periods. SENSITIVE AREA EVALUATION Seismic Hazard Medium dense to very dense glacial soils were encountered underlying the site. Based on the 2003 International Building Code (IBC), the site conditions best fit the description for Site Class D. Hazards associated with seismic activity include liquefaction potential and amplification of ground motion by soft deposits. Liquefaction is caused by a rise in pore pressures in a loose, fine sand deposit beneath the groundwater table. The medium dense to very dense glacial material interpreted to underlie the site has a low potential for liquefaction or amplification of ground motion. NELSON GEOTECHNICAL ASSOCIATES, INC.