10200 19TH AVE SE COSTCO FUEL STATION Geotech Report 2022-10-25

APPENDIX A FIELD EXPLORATION E-8556 Our field exploration was performed on January 5, 1999. Subsurface conditions at the site were explored by drilling four borings to a maximum depth of twenty-five (25) feet below the existing grade. The borings were drilled using a truck-mounted drill rig. Continuous-flight, hollow-stem augers were used to advance and support the boreholes during sampling. Approximate boring locations were determined from existing landmarks presented on available plans. The locations of the borings should be considered accurate only to the degree implied by the method used. These approximate locations are shown on the Boring Location Plan, Plate 2. The field exploration was continuously monitored by an engineer from our office, who classified the soils encountered and maintained a log of each boring, obtained representative samples, measured groundwater levels, and observed pertinent site features. All samples were visually classified in accordance with the Unified Soil Classification System —which is presented on Plate Al, Legend. Logs of the borings are presented in the Appendix —on Plates A2 through A7. The final logs represent our interpretations of the field logs and the results of the laboratory tests of field samples. The stratification lines on the logs represent the approximate boundaries between soil types. In actuality, the transitions may be more gradual. In each boring, Standard Penetration Tests (SPT) were performed at selected intervals in general accordance with ASTM Test Designation D-1586. The split spoon samples were driven with a one hundred forty (140) pound hammer freely falling thirty (30) inches. The number of blows required to drive the last twelve (12) inches of penetration are called the "N- value". This value helps to characterize the site soils and is used in our engineering analyses. Representative soil samples were placed in closed containers and returned to our laboratory for further examination and testing. Earth Consultants, Inc.