10200 19TH AVE SE Geotech Report 2018-01-02 MF Import

finishes. Heating oil USTs (underground storage lanks) may also be przsent. 'll�ese shovld be remov�;� and site assessment procedures per Ecoloyrv(JVashington State Depaztment of Ecology) followad during the removal process. Within the building footprint and within pazking and drive azeas where less than 2 feet of ' new fill is planr,ed or where cuts will be made (e.g., southern and western porcion of the site), we recoaunend that all vegetation, induding the sod zune, be removed. We estimate th;:t the depth of saipping necessary to remove the sod zone will vary from less than 6 inches over the central portion of the site to about 6 to 12 inches over other azeas. Thicker organic and root ! wnes will be encountered in the forested azeas. Roots lazger that 1-inch diameter should be ' ' . yrcubbed to at lease 12-inches below design subgrade. We also recommend that all surficial � � " � organics be removed from the wedand azeas that aze to be filled. 'It�e thickness of surficial • organics in these wetland areas appears to vazy from about 1 to 3 feet in thickness. � : In pazking and drive areas where more than 2 feM of new fill is planned (i.e., the no�thern '� and eastern portions of the site),tae sod:.one may be left in place if it is not disturbed by general � ' site clearing activities. The grasses should be cut az short as practical and the clippings removed prior to fill placement. Stumps, brush and associated lnrger root systems should be removed. • Prior to placing any fill, we recommend that.tl�e exposed subgrades in pavement and slab � . ' azeas be evaluated by thoroughly prooholling with heavy rubber-tired conswc!ion equipmeat . (dry weather construction) or by probing (wet weather construction). We recommend that all � loose or sofr azeas be compacted to a dense nonyielding sWte. It may be necessary to moisture condition the soils to achieve adequate compaction. If the subgrade cannot be adequately compactad or if the work is performed during wet weather, all soft or loose zo,�es should be � removed and replaced with swctural till to the depth determined by the geotechnical enginerr. The excavated material should be placed in nonsettlement-sensitive areas (e,g., ]andscaped areas) or removed from the site. STRUCTURAL FILL Fill soil should be placed as compacted structural fill except in areas to be landscaped. Structural fill should be free of debris, organic matter and cobbles lazger than 5 iaches. 'Ihe suitability of soil for use as structural fill witl depend on its gradation and moisture content. As the amount of fines (soil particles passing No. 200 sieve) increases, soil becomes increasingly more sensitive to small changes in moisture content and adequate compaction becomes more difficult, if not impossible, to achieve. We recommend that sauctural fill for wet weather conditions consist of impocted sand and qravel with less than S percent fines. During periods of eztended dry weather, the fines content m3y be increased somewhat, provided that the moisture content can be controlled to achieve adequate compaction. The floor slab and pavement should be underlain by capillary break aad subbase materials, resputively, as described later in this report. The glacial till soils a�e suitable fur use ae structurat :�!:provided that the moisture content is near optimum and adequate compaction can be achieved. If previously placed "uncontrolled' G e o E n g i n e e r � $ Fik No.0975-017-R73106I993