10200 25TH AVE SE Geotech Report 2018-01-02 MF Import

J Proposed Modernization and Additiorrs ta Subsurface�'xp[orarion, Geo[ogic Kazards, Eisenhower Middle School and Georechnica!Engineering Re�ort Everett. WashinRton DesiRn Recommendations III. DESIGN RECO�IENDATIONS 7.0 INTT<ODUCTIOPd Our exploration indicates that, from a geotechnical standpoint, the proposed project is compa�:3(e with this site provided tbe recommendations containrd herein are properly followed. The foundation bearing strata (till) was encountered below 1 to 12 feet of relatively loose fill. The soils Ancountered at the soil/till contact were generally above their optimum moisture content for compaction, thus their rwse as structural fill during all but the driest times of the year will be difficult. Where suitable foundatica bearing soils are encountered near foundation elevation as anticipated in the viciniry of EB-I northerly adjacent to the "circular" building, conventional shallow foundations and slab-on-grade floors may be used with normal site preparation procedures. Fill ro a depth of 6 fe..t is anticipated in the vicinity of the eighth grade classroom and library additions. Existing fill, where encountered, shoufd be removed from beneath planned foundations, ftoor slabs, and any other setdement-sensitive structures. Where existing fill cannot be removed and replaced with structural fill due to the proximity of existing structures/foundations, an alrernare foundation syste� � such as pin piles or short aggregate piers (GeopiersT"') or rock trenches could be ��.ced to support building foundations through areas � underlain by existing fill soils. Where fill de�ths are shallow, recompaction of existing fills in ' place is possible, provided tt.e fills are at a moisture content that allows for the required compaction. The following rzpert sections present our specific geotechnical site development recommendations. 8.0 SITE PREPARATION All foundations, paving, and other structures that are present under the planned building and pavement areas should be removed. Any buried utilities should be removed or relocated if they are under the proposed buildings. The resulting depressions shouid be backfilled with structural fill as discussed under the Stn�cn�rn! Fill section. In development areas that are currendy occupied by landscaping, all vegetation and topsoil should be removed during site prepara[ion. Where footings and slabs are to be supported on compacred fill, the existine unsuitable fill soil should be removed io expose firm, unyielding till. The removal of existing fill soil should extend laterally beyond the building footprin, a distance equal to the depth of suitable soils below planried foundations. For example, if unsuitable soil extends 3 feet below planned Jnnunn�13, 3COd dSSOGATED Fa1RTH SC/E:VCES, 1NC. 2 .tIP(J-Af0iD3dJ-Prn�rnaL001iJtl'.X6'l1YP-lV)K P'1gC IO J7