2920 CHESTNUT ST 2016-01-01 MF Import

David Kehle, Architect W-3574 9 April 1981 Page Two SUBSURFACE COND[T[ONS This site has been previously filled with a loose, brown, silty sand containing some soft topsoil , peat, concrete and boards. This fill ranged in thickness from 2-1/2 feet to more than six feet. Beneath the fill we encountered a medium stiff to hard, sandy, clayey, silt. This silt is on the order of two, to more than three feet thick. In Test Pit kl and k3, this silt stratum is underlain by a dense, silty sand with gravel . At the time of field work, some seepage was noted in the sands below the silt horizon. In addition, water can become perched on the fill , at random levels within the fill and atop the silty original ground. DESIGN CONSIDERATION I. General The existing fill should not be considered adequate for support of the planned structure. Instead, structural support should be gained from the underlying very stiff to hard silts, or the dense, silty sands. Based on our soils exploration, it appears that adequate bearin9 may be encountered at approxi- mately 1-1/2 to 2 feet below the orignal , natural ground surface. II. Site Preparation For areas to recieve compacted fill , or to be utilized for structural support, all existing fill , topsoil , and unsuitable natural soils should be removed. If the stripping is done during cool , damp, or wet weather, great care should be exercised by the contractor, since these soils are very silty in nature and soil disturbance can greatly increase the amount of material to be excavated. After stripping, the ground surface should be scarified and recompacted. Fill should then be placed in 8-inch horizontal lifts and compacted to at least 90% of laboratory maximum density using ASTM:D-1557 (AASHTO:T-180), as the standard. i