2000 TOWER ST ARTS AND SCIENCES BLDG 2018-01-02 MF Import

EXECUTIVE SUMMARY This report contains the results of our geotechnical engineering services for use in the design of the proposed Art and Science Building at Everett Community College. The project consists of constructing a new three-story building in the existing parking lot located south of Shuksan Hall. The first floor level (Level I building area) will daylight to the cast with partial below -grade walls to the west. The second floor level will have partial below -grade walls in the southwest area of the building. SUBSURFACE CONDITIONS The subsurface conditions at the site were evaluated by drilling five borings in the footprint of the buildir.2. Based on our explorations, the near -surface soils generally consist of glacial till overlying advance outwash. The glacial till consists of dense to very dense silty sand with gravel. Significant groundwater was not encountered in the borings, although a few wet soil layers were observed. !i4mLICWei*3DTJ In accordance with the 1997 Uniform Building Code (UBC), the site is classified as a Soil Type Sc. Likewise, in accordance with the 2003 International Building Code (IBC), the site is classified as Soil Profile Type C. REUSE OF ON -SITE MATERIALS The native glacial till is expected to be suitable for use as structural fill during the summer months and may be used as fill in the wet weather months in areas needing only 90 percent compaction (ASTM D 1557) by utilizing good construction practices. We do not recommend using the native glacial till during wet weather when 95 percent compaction is required. Recycled asphalt pavement and base course from the existing parking lot may be reused as structural fill under future pavement areas and against basement walls. TEMPORARY CUT SLOPES Excavations for the first Floor level will require cuts up to about 10 feet deep in the southwest area. Cuts on the order of 4 feet will be needed for the below -grade level in the southwest comer of the second floor level. These cuts can be ntaue as temporary open cut slopes depending on site constraints. Temporary unsupported cut slopes more than 4 feet high may be inclined at 3/411:1 V (horizontal: vertical) maximum steepness within the dense to very dense glacial till. FOUNDATION DESIGN The building can he supported on conventional spread footings bearing on undisturbed dense to very dense glacial soils or on structural fill placed over these soils. The first and second level footings may be designed using an allowable soil bearing value of 8,000 pounds per square foot (psf). Footings bearing on structural fill placed over undisturbed dense glacial soils may be designed using an allowable soil bearing value of 3,000 psf. The allowable bearing value may be increased by one-third for short duration loads such as wind or seismic events. G e 0 8 n g i n c e r s ES-1 Fite No. 5836-002.00,040204