4027 4TH ST SE 2018-01-01 MF Import

January 14, 2003 HWA Proiect No. 2002-146-21 and testing. Apoendix A contvns additional discussions regazding the field exploration method, as woll as the log of fne boring. 2.2 LABORATORYTESTING Laboratory tests were conducted on selected soil samples to characterize certain engineering (physical) properties of the on-site soils. Laboratory testing included determination of natural moisture content, grain size distribution, and Atterberg Limits. A soil sample of the southem stockpile was obtained and tested to determine its moisture density relationship. Testing was conducted in general accordance with appropriate American Society for Testing and Materials (ASTM) standazds, as discussed in Appendix B. The test results are presented in Appendix B, or displayed on the exploration log in Appendix A, as appropriate. 2.3 LITERATURE REVIEW We reviewed available existing information regarding previous geotechnical explorations performed at or near the site and historical pile driving records from construction of the adminisvation building and the chlorine contact channel. Sources of information obtained and reviewed for this project aze listed in the reference section of this report. Copies of pertinent boring logs and cross-sections are provided in Appendix D. 3.0 SITE CONDITIONS 3.1 GENERAL The site is located on Smith Island, an island neaz the mouth of the Snohomish River that was likely an old sand bar built up using dredged ma�erial from the Snohomish River. Some areas of the existing treahnent plant have reportedly been preloaded during previous site work (HWA, 2002); however, no preloading has been documented at the proposed new maintenance building site. Existing grades within the proposed building tootprint range from 6 to 1 I feet and slope gently to the east. 3.2 REGIONAL GEOLOGIC CONDITIONS The project site is located in the Snohomish River valley, a broad, flat valley through which the Snohomish River has meandered since the retreat of the last glaciers. The gcologic map for the azea (Minard, I985) indicates that near surface soils consist of younger alluvium. Minard describes alluvial soils as soils that consist of unconsolidated, stratified, clay, silt and sand with abundant organic material. He indicates that medium coa. se sand and gravel rypically undedie the fine grained floodplain sediments and that peat i• oosits and buried logs and stumps are common in the flood plain of the Snohomish River. Duc ro the mode in which the alluvial soils were deposited, they aze :002146 rt�wn - Glul H1VA GEOSCIENCEs INc.