600 RIVERSIDE RD Geotech Report 2022-10-25

I ,C] APPENDIX A ' FIELD EXPLORATIONS Subsurface conditions at the project site were explored on March 9 and 14, 2017. The exploration program consisted of advancing and sampling two exploratory borings (B-1 and B-2) and five exploratory test pits (TP-1 through TP-4 and TP-413) at the approximate locations illustrated on the Site and Exploration Plan (Figure 2 of this report). Both borings were advanced to a depth of about 31.5 ft below the existing ground surface (bgs) using the hollow -stem auger exploration technique. The test pits were excavated to depths ranging from about 5 to 9.5 ft bgs. Environmental Drilling, Inc. of Snohomish, Washington advanced the hollow -stem auger borings and Northwest Excavating and Trucking of Snohomish, Washington excavated the test pits under subcontract to Landau Associates. The locations of the explorations were located approximately in the field by measuring distances to nearby features. The field exploration program was coordinated and monitored by Landau Associates personnel who also obtained representative soil samples, maintained a detailed record of the observed subsurface soil and groundwater conditions, and described the soils encountered by visual and textural ' examination. Each representative soil type observed in our exploratory borings and test pits was described using the soil classification system shown on Figure A-1, in general accordance with ASTM International (ASTM) D 2488, Standard Recommended Practice for Description of Soils (Visual -Manual Procedure). Logs of the explorations are presented on Figures A-2 through A-7. These logs represent our interpretation of subsurface conditions identified during the field exploration program. The stratigraphic contacts shown on the summary logs represent the approximate boundaries between soil types; actual transitions may be more gradual. The soil and groundwater conditions depicted are only for the specific dates and locations reported and, therefore, are not necessarily representative of other locations and times. A further discussion of the soil and groundwater conditions observed is contained in the text portion of this report. Representative grab samples of the soil encountered in the exploratory test pits were obtained as the test pits were excavated. Disturbed samples of the soil encountered in the exploratory borings were obtained at selected intervals using a 1.5-inch inside -diameter split -spoon sampler. The sampler was ' driven up to 18 inches into the undisturbed soil ahead of the drill bit with a 140-lb hammer falling a distance of approximately 30 inches. The number of blows required to drive the sampler for the final ' 12 inches of soil penetration, or part thereof, is noted on the boring logs, adjacent to the appropriate sample notation. Samples collected in this manner were taken to our laboratory for further examination and testing. A discussion of laboratory test procedures and the laboratory test results are ' presented in Appendix B. Upon completion of excavating and sampling, the test pits were backfilled in lifts with the excavated ' soil. Upon completion of drilling and sampling, the boreholes were decommissioned in general accordance with the requirements of Washington Administrative Code (WAC) 173-160. A-1 L