11831 AIRPORT RD WHOLE SITE FILE Geotech Report 2022-10-25

Crushed Station Rock Base Site Number or HMA Course Plan Exploration Location Improvement (inches) (inches) Figure GEI-16 Airport Road and SR 99 3021 N/A(grass) - 20 GEI 17 Northbound Airport Road at 3020 111/2 0 2P 112th Street SW GEI-18 Airport Road and 100th Street SW 3019 N/A(grass) - 2Q GEI 19 Southbound Airport Road at 3037 6 4 2R Kasch Park Road Subsurface Soil and Groundwater Conditions The subsurface conditions vary significantly throughout the project corridor. For ease of discussion we have separated the project corridor into 15 segments proceeding from south to north. Logs of the borings and hand augers conducted as part of this study are presented as Figures A-2 through A-29 in Appendix A. Canyon Park Park-and-Ride and SR 527 at 220th Street SE Boring GEI-1 was drilled near the southwest corner of the Canyon Park Park-and-Ride parking lot,as shown on site plan Figure 2A. Hand auger HA-1 was completed on the slope in the northeast corner of the intersection of SR 527 and 220th Street SE, as shown on site plan Figure 2B. Boring GEI-1 and hand auger HA-1 were completed to depths of 11/and 8 feet below the existing ground surface(bgs), respectively. Fill was encountered in both of the explorations at these locations.The fill varied in composition, but was generally loose to medium dense silty sand and sand with silt with gravel and organic material.The fill extends to a depth of approximately 7 feet bgs and is underlain by medium dense silty sand and sand with silt with gravel and organic matter. Stiff silt overlying dense silty sand was encountered in the WSDOT boring completed near HA-1 (MH-2). Groundwater was observed at the native soil contact in both explorations at the time of drilling. SR 527 at SR 524 Boring GEI-3 was drilled in the southbound outside lane of SR 527 that accesses the shopping center south of the intersection with SR 524 (refer to Figure 2C). Boring GEI-4 was drilled in the right turn lane from southbound SR 527 to westbound SR 524, as shown on site plans Figure 2C and 2D. Borings GEI-3 and GEI-4 were completed at depths of 151/2 and 14 feet bgs, respectively. Medium dense fill was encountered below the pavement section in both borings, extending to a depth of 5 to 7 feet bgs. The fill consists of silty gravel with sand and silty sand with gravel and cobbles. Dense grading to very dense silty sand with gravel and cobbles underlies the fill. Limited recovery was encountered in several of the samples due to the gravel and cobble content. We interpret the soil to be glacial till. We did not encounter groundwater at this location during drilling, however wet soil samples were recovered at the bottom of the borings. GEOENGINEERS� April 14,2017 Page 5 File No.2095-032-00