soil exploration/geoptechinical investigation-2004

Home Browse Search

feet must have at least 2 percent drainage grades. Roof water run-off must be permanently controlled with roof drains and downspouts discharging on long splash blocks or into subsurface pipes that discharge far from buildings and structures. FLOOR SLAB SUB-GRADE PREPARATION As stated in the GROUND WATER section of this report, we observed in-filled water in Borings 1 b and 2 at respective depths- near 5 and 4 feet at the end of drilling. Based on FHA construction standards, we recommend elevations of lowest building floors be at least 4 feet above maximum anticipated ground water level. — Excavation and earthwork construction must include preparing reliable ground support for floor slabs. This support must be structural fill at least 12 inches thick. Before placing structural fill beneath floors, the exposed bottom sub-grade surface of the structural fill must be vibro- compacted using several passes of the compactor, to increase its density and shearing resistance strength. Preparing the structural fill sub-grade beneath floor slabs. must be made according to recommendations in,the EXCAVATION AND EARTHWORK section of this report Floor slab sub- grades prepared as described above can be designed using a modulus of sub-grade reaction of 100 pounds per cubic inch (pci). The garage area of the building may be subjected to freezing temperatures during.its life. Ground- supported floor slabs subjected to freezing must be protected against frost heaving. Floor slabs supported on frost-susceptible soil can potentially heave differentially. Therefore, a buffer must be placed between floor slabs and frost-susceptible soil to minimize heave. We recommend placing non-frost susceptible granular buffer material beneath floor slabs. This material must contain less than 5 percent fines that pass #200 sieve, and it must be free-draining to reliable and permanent drain lines. The buffer must be at least 18 inches thick. EXCAVATION AND EARTHWORK Clearing and grubbing may be required to remove all trees, brush, stumps, roots, and designated existing structures within the clearing limits. Stump holes and removed structures should be filled with compacted structural backfill to prevent localized subsidence in planned construction areas. Topsoil with undecomposed organic matter (grass, roots, decayed vegetation and organic odor) must be removed from project.areas designated for construction of structural fill, buildings and structures, roadways, driveways and other improvements. Consideration can be given to reusing -- removed topsoil in designated landscape.areas and as replacement topsoil. The structural fill sub-grade must be prepared to support structural fill loading. Remove all unsuitable and unreliable soil beneath structural fill and replace with structural backfill. Unsuitable soil includes but is not limited to the following kinds: soft compressible clay, peat and muck; debris T and rubble; potentially expansive .soil (relatively plastic and fat clay); potentially collapsible soil (loess and "bulking-type" sands); topsoil and buried topsoil with undecomposed organic matter (usually contains grass, roots, decayed vegetation and organic odor); organic soil (OL and OH -- types); uncontrolled and undocumented fill. Allied Project 04049 10 July 27, 2004