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1 <br /> • s�,nsu�o��e��m�arro», Geologic Hazard. and <br /> Everett School District Maintenance Far.ility Preliminary Geotechnicn!Engineering Repon <br /> Everett, Washingmn Design Recommendations <br /> 8.0 SITE PREPARATION <br /> Gxisting strucmres, old foundations, and buried utilities undcr new buildings should be <br /> remove�l and properly disposed of off-site. Whcrc basements currendy exist below the <br /> proposcd lighdy loaded strucmres or below the propo;ed parking areas, they can be filled with <br /> compacted structural fill (see section 9.0 or if within 100 feet of the vibration sensitive <br /> buildings filled with lighdy compacted (track walked or static drum rolled) pea gravel, quarry <br /> spalls, railroad ballest, or similar clean rock fill and then topped with contro► densiry fill <br /> (CDF). 1'he concrete derived during building demolition can be r,rushed to 4 inch minus size <br /> and used for structural fill if the crushing �peration is condur.ted more than 100 feet from the <br /> ��ibration sensitive building. Basement slabs can be left in place if perforated to prevent water <br /> collection. The basement walls shculd be removcd to a �epth of at least 3 feet below new <br /> fo�tings elevations. The CDF should extcnd at Icast 1 foot bclow thc base of the new footings. <br /> For higher load areas, the basement walls and iloor should bc removed and the hole filled with <br /> loose, track walked, rubble free fill soils and ncw building supported on drilled piers or <br /> augercast piles extending through the 611 into the glaciol:icustrine soils. <br /> Undrr lightly loaded structures in areas without existine hasements, the upper 3 feet of existing <br /> fills below new foundations should be mmoved and replaced with strucmral fill. Along with <br /> ( existin; structures, old foundations, and buricd utilitirs existing fill under new parking arcas <br /> � should Ue proof-rolled and compacted to 12 inches bclow proposed pavement subgrade. Thc <br /> resulting depressions should be backfillecl with structural till as discussed under the Strt�carrril <br /> Fr!! section 9.0. Compaction should be limited to static. non-vibratory rolling, preferably by a <br /> large drum compactor, within 100 feet of the viUration scnsitive building. <br /> :\reas where loose or soft surficial soifs rcmain in the parking areas or at 3 feet below Qie <br /> lighdp loaded buildings may require additional over-cxcavation and replacement by structural <br /> lill. 'Che depth and extent of over-escavation can brs� be determined in the field by thc <br /> geotechnical engineer or engineering geologist. ��'e recommend that parking areas be <br /> proofrolled with a loaded dump truck to identiCy any soR areas. Generally, over-excavation <br /> greater than 4 feet below pavement grades and 5 feet below the lightly loaded huildings �vilf <br /> not he necessary. <br /> In our opinion, stable construction slopes sliould be the responsibility of [he contractor ar.d <br /> should be determined during construction. For esti�na�ing purposes, however, we anticipate <br /> that temporary, unsupported cut slopes in the fill can be made at a maximum slope of 2H:IV <br /> (Florizontal:Vertical) �vhile unsupported cuts in the glaciolacustrine may be made at a <br /> maximum of 1.51-I:1V. As is rypicaf with earth�vork operations, some sloughing and raveling <br /> may occur and cut slopes may have to be adjusted in the field. In addition, WISHA/OSHA <br /> rcgulations should be followed at all times. <br /> , ,Yfay !, 2C01 ASSOClATED F11RTX SC(ENCES, INC. <br /> JDCGa-RFOIOSIdI-D:b�yil�it01-W A Page 8 <br /> �d <br />