2400 33RD ST GEOTECHNICAL INVESTIGATION 2018-01-02 MF Import

The findings of the pavement investigations are described in Table 1 below. The grab samples are described in the table be'.3w. SITE CONDITIONS Surface Conditions As shown in Figure 1, the site is bounded by 33rd Street to the south, the BNSF right-of- way to the west, and the Pacific Avenue Overpass to the north. To the east, there are a row of commercial/industrial buildings, which front onto Hill Street. The site has been cleared of structures and debris and is covered with crushed, compacted granular soil. There is a temporary drainage detention pond in the southeastern portion of the site, which is approximately 20 feet by 105 feet by 4 feet deep. Based on the results of our coring explorations, it appears that there is Portland Cement Concrete (PCC) pavement beneath Asphalt Concrete (AC) pavement in the northern two- thirds of Hill Street, as shown by the red line on Figure 1. There is also PCC beneath the AC under the southern half of the pavement under the Pacific Avenue Overpass. The thicknesses are described in Table 1. Subsurface Soil Units The MPA October 2001 report describes the subsurface soil units at the site. Covering the site, we understand that there is a 1.2 to 1.5 foot layer of crushed granular material. This layer is potentially contaminated with arsenic. The subsurface soil units in the roadway are described in Table 1. Table 1.11avement Investigation Results Caring Thickness of Final Method of Comments Number Pavement in depth Pavement Inches of Excavation hole Asphalt PCC (AC) NlpC-1 3.5 0 4' Jackhammer Subgrade to 10"-Crushed 1.5" minus. 10"-Brown, coarse gravelly, silty fine to coarse SAND; 30"-1Vaterseep; blue -gray silty CLAY. R11'C-2 S (1 3'8" Jackhammer Subbrade-Very dense, brown, silty fine to medium SAND, trace fine gravel. I' -transition to stiff, mottled brown and blue -gray, silty CLA i . 2.5'-Stiff, blue ray silly CLAY; rod pen. 3"to 4". All'C-3 10 0 •1' Jackhammer PY-Ceramic piece in soil; 1.5'-Soft, dark brown, silty fire to medium SAND, trace coarse sand, wood chips; 8" pen. of rod. 2'-Odor of rotting wood. Transition to brown[blue-gray clayey silt at 3'. MPCA 0 0 5'8" Core 1.5' -V. dense, brawn, slightly silty fine to t,edium SAND, trace coarse sand; !'x " pen. of rod. YV. dense, slightly silty fine SAND. Geolechnical and Tunnel Consultants 17270 Woolit. Mlle -Redmond Rd, Ste 703 Phone (425) 486- 'i561 Woodinville, WA 98072 Page 3 Fax (425) 4882660