2205 BROADWAY 2016-01-01 MF Import

LSI -ADAPT To have a high potential for liquefaction, a soil must be cohesionless with a grain siv: dishibution of a specified range (generally unifortn sands and silry sands); it must be loose w medium dense; it must be below the groundwater table;and it must be subject to a sufficient magnitude and duration of groundshaking. Due to relatively high in-placc density of the soils and the lack of significant near surface groundwatet,it is our opinion that the liqucfaction potential for this site is low. Slab-on-Grsde Slab-on-grade floors may bc consWcted on stitl' or medium dense or dcnser or native soils, or upon sVuctural fill placed abuve these undisturbed soils. Subsequent to excavation of the site,we recornmend that the exposed soils Ue compacted and proofrolled to verify a finn,non-yielding condition. If soft or loose soils are encountered,they should be re-compacted or removed and replaced wilh structunl fill. i , After proof-rolling,the building slab areas should be provided with a capillary break material consisting of 6 ' inches of clean building sand or gravel. This material should be free draining and wntain less than 3 percent fincs. We would also recommend the utili7ation of a vapor bartier such as a 6-mil plastic mcmbrane to prevent moisture buildup beneath the concrete slab. Two inches of damp sand may be placed over the membrane for protection during constr;�ction and to aid in curing of the concrete. Gxr.a��ations and Slopes The stability of cxcavated cut slopes depends oa a number of factors, induding the prescnce and quantiry of water, the type and dcnsity of the excavated soil; the depth of the cut; the presence of surcharge loads from construction equipment, stockpi:ed soils, und thc like; the schedule of construction, and care and methods used by the contracror. Beaause of the variables involved, actual slope values required for stability in temporary cut areas can only be estimated prior to conswction. Temporary cut slopes(foundation and utility excavations)will be neceasary during gading operations. As a gener�l guide, temporary slopes of I.5 H:1V (Horizontal to Vertic:�i� ��r 1lauer may be used for tem.poruy cuts in the stifTor tredium dense or denscr native silu and silry sana soils encountered at a shallow depth on the site. Thcse guidelines assume that all sudace loads are kcpt at a mi��imum dis!ance of at least��ne half thc dcpUi of the cut away from the top of thc slope ant that signifcant seepagc is noi present on ihe slope face. Flatter cut slopes will bc necessary where signif�c__� ml moisture or seepage occurs. All cut slopes should be properly protected. Tempora�y slopes may necd plastic shceting to protcct from loosening caused by prccipitation or cxcessive drying. Keep construction cquipment, workers, and matcrials at least five fect back from the slope. We recommend that thc stability of temporary cut slopes be made the responsibiliry of the contractor, sincc he is in convol of thc construction operation and is ' ' LSI-ADAPT Job No.WA02•8721 . Paa°�� Augusl6,2002