10632 7TH AVE SE Geotech Report 2025-07-28

I June 6,2008 Serenity Meadows L&A Job No. 8A017 Page 8 site. To further mitigate the erosion hazard, the vegetation cover outside of construction limits should be preserved and maintained, and unpaved exposed ground within the site resulted from construction activities should be re-vegetated as soon as possible. Concentrated stormwater should not be discharged uncontrolled onto the ground within the site. Stormwater over impervious surfaces,such as roofs and paved roadways, should be captured by underground drain line systems connected to roof downspouts or by catch basins installed in paved roadways and driveways. Water collected by these drain line systems should be tightlined to discharge into a storm sewer or a suitable stormwater disposal facility, such as a bio-filtration swale. Seismic Hazard and Design Consideration The Puget Sound region is in an active seismic zone. The subject site is underlain at shallow Idepth by dense to very-dense,fresh, advance outwash or till soils of moderately-high to very:high shear strength. There is a lack of continuous, extensive, static groundwater table at shallow depth under the site. The site is mostly gently to moderately sloped. The combination of the above makes it rather unlikely for seismic baards, such as liquefaction or soil lateral spreading, Ito occur on the site during strong earthquakes. Therefore, the seismic hazard of the site should be minimal. The residential buildings to be constructed on the site,however, should be designed to withstand seismic forces induced by strong earthquakes. Based on the soil conditions encountered by the test pits, it is our opinion that Seismic Use Group I and Site Class D should be used in the seismic design of the proposed residences in accordance with the 2003 International Building Code{IBC). SITE PREPARATION AND GENERAL GRADING Site preparation should include clearing and grubbing within construction limits. Existing structures on the site to be demolished should also have their foundations removed. Weak surficial soils should be stripped down to medium-dense weathered soils within the roadways and down to the underlying dense to very-dense, fresh, advance outwash and/or till soils within LIU & ASSOCIATES, INC.