2408 RAVENNA ST 2016-01-01 MF Import

� Geocechnical Engineering FLeport ` � v Lowel]Short Plat June 2, 1999 NCA File No. 259499 Page 8 Foandations Conventional shallow spread foundarions should be placed on undisturbed medium dense or better native sar.ds, or stiff or better silts, or be supported on shvctural fif I or rock spalls extendibg to those soils. I'he excavation should be made through all existing fiil. The overexcavatiun could be fillai with shvcuual fili, or the footiug may be extendc�l down m the ow7ng native soils. �' foorings are suppoAed on structural fill,the fill zone should extend outside the edge of the footing a distanx equel to ono-half of the depth of overoxcavation below the footing. Footings should extend at least 18 inches below the lowest adjacent finished ground surfece for frost probection and beariag capacity conside�ations. Minimum roundation widths of IS and 24 inehes should be used for continuous and iso►ated spread footings, rcspcctively. Stending water should not be allowed w eccumulate in footing trenches. Alt Ioose or dieturbed soil ..,ould be rnnoved from the fouadstion excavation prior to placing conoreu. For foundations constructed as outlined above, we recommend an allowable design be+uing pressure of not more thaa 2,000 pounds per square foot(ps�be used for the footing design. Current Llnifurm Building Code (UBC) guideliaes shoutd be uud whea considering increased allowablc bearing pressuro for short-term transitory wind or seismio loads. Potential foundation settlement using the recommended allowabie beazing pressure is eatimated to be less than 1-inch total end I/Z-inc6 differential between footings or across a distance of nbout 20 feet. 'I'he soils that will be e:cposed in foodng excavations are ]ikely to be highly moishue sensidve. If e�cc�vated in wet weather, care should be used in subgrede preparadon. A smooUrbucket excavatrn or pulied beam to smooth the r.ccavation should be used in wet conditions. Also a 4-to 6-inch cnuhed rock or gravel layer may be needed to protect footing subgrade from disturbance during form placement Slabs-on-Grade Tiu subgrade for slabs-on-grade should be prcpaicd as oudined in our Site Prepantloo wd.Gradirg subseetion. Areas of fill or soils that are observed to weave during compactioa should be overexcavated and replaced with structuial fill. Whern moisturo control is important, we reeommend that at least 6 inches of free-draining material be placed under slabs-on-grade to aet as a capillary break. 'I'he eapillary Ureak material s6ou(d be separsted from slabs by a vapor barrier, such es plastic shxring. Au additional • . NELSON-COUVRETTE 8 ASSOCIATES, INC.� T!