8215 BROADWAY 2016-01-01 MF Import

ADaPT Eo�incerieQ, Iac. Suberades and Testin¢: Regardless of location or material, all shvctural fill should be placed ovtt fitm, unyielding subgradc soils. We recommend that a representative from ADaPT be retained to observe the condition of subgrade soils before fill ptacement begins, an�. to perform a scrics of in-place density tests during �oil fi!1 placement. In this way, the adequacy of soil compaction eti'orts may be evaluated as earthwork progre:ses. Pill Contcnt: Soils used for strvctural fill should not contain individual particles greater than about 6 inchcs in diameter and should be free of organics, debris, and other deleterious materials. Givcn these prerequisites, the suitability of soils used for structural fill dcpends primarily on the grain-siu distribution and moisture content of thc soils when ihey arc placed. When the "fines" content (ihat soil fraction passinF the U.S. No. 200 Sicve) increascs, soils become more sensitive to small changes in moisture content. Soils containing more than about 5 percent fines (by wcight) cannot be consistently compacted to a firm, unyieiding condition when the moisture content is morc than about 2 perccntage points above optimum. 'fhe cxisting ncar surface soils at this site consists of loose to medium dense silty sand with gravcl, and should be considered highly moisture sensitive. The usc of "clean" soil is necessary for fill placement during wet-weather site work, or if the in-situ moisture content of the silry sand soils is too high to allow aScquate compaction. Clcan soils are defined as granular soils that have a fines content of less than 5 percenl (Uy weight) based on ihe soil fraction passing the U.S. No.3/4-inch Sievc. CLOSURE The conclusions and recommendations prescntcd in this report are based, in part, on the explorations that we performcd for this study. If variations in subsurface conditions are discovercd during earlhwork, we may nced to modify this report. The futum perfortnance and integrity of the tower foundations will depend largely on proper initial site preparation, drainage, and constrvction procedures. Monitoring by experienced gcotcchnical personnel should be considered an integral parl of Uie consWction process. We arc available to providc geotechnical engineering services during lhe earihwork and foundation conshvction phascs of the project. If variations in the subgrade conditions are observcd at that time, we would bc ablc to provide additional geotechnical recommendations, thus minimizing delays as the project develops. Wc are also availablc to review prcliminary plans and specifications beforc construction begins, and to provide gcotechnical inspection and tcsting scrvices during construction. VoiceSlream Wircicss May 19,:D00 ADaPT Pmjccl No. WA00-4034 p�gc 9