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� <br /> � GROUND FLOOR <br /> SLAB SUBGRADES <br /> Based on FHA construction standards, we recommend placing the lowest building floor elevation at <br /> ! least 4 feet above maximum anticipated ground water level. As stated in the GROUND WATER <br /> section of this report, water was detected in Borings 1 and 2 near depths of 8 and 9 feet� <br /> Irespectively. The Boring Logs reveal that supraglacial till appears to have both oxidized and <br /> unoxidized soil zones. The oxidized soil zone extends down to depths near 13 feet, and it is not <br /> related to a persistent ground water condition. The oxidized zone overlies the unoxidized soil <br /> ( zone, which is associated with a persistent ground water condition. <br /> � Ground floor slabs must be supported on structural fill at least 12 inches thick that meets <br /> ; requirements in the EXCAVATION AND EARTHWORK section of this report. The structural fiH <br /> must be supported on reliable material meetirrg requirements in the STRUCTURAL FILL <br /> SUBGRADE section of this report. Ground floor slabs supported on such structural fill shouid be <br /> designed with a subgrade reaction modulus of 100 pounds per cubic inch (pci). <br /> Placement of the structural fill must allow for installation of a moisture barrier (water and water <br /> vapor) directly beneath the floor slab. The moisture barrier is described in the WATERPROOFING <br /> section of this report. Building codes typically call for placing a water vapor barrier (polyurethane <br /> sheeting at least 6 mil thick) directly beneath the floor slab. Sheet seams must be completely <br /> sealed to prevent water vapor migration. These codes also call�for placing a layer of clean free- <br /> draining sand 6 inches thick directly beneath the vapor barrier to drain water. The sand layer must <br /> extend laterally to perForated drain line pipes. <br /> Floor slabs for garages and other open bays that may freeze during their lives must be protected <br /> against differential frost heave movement. Remove all unsuitable frost-susceptibie material <br /> beneath floor slabs to a depth of at least 30 inches beneath floor slabs. This materaal contains <br /> over 5 percent fines passing the #Z00 sieve, and it is not clean and free-draining. Replace this <br /> material with granular structural fill at least 24 inches thick extending up ta the floor slab according <br /> to the OVER-EXCAVATION AND STRUCTURAL BACKFILL section of this report. The granular <br /> stnactural fill must contain up to 5 percent fines passing the #200 sieve, and it is clean and free- <br /> draining. Placement of granular structural fill must allow for installation of a moisture barrier <br /> beneath floor slabs. This installation is described in the above paragraph. If the granular structural <br /> fill drains poorly, water may accumulate in it and freeze into a mass of ice that heaves the slab. <br /> FOUNDATION EMBEDMENT PROTECTION <br /> BACKFILL CAP AND WATER RUNOFF Foundation backfill must be capped with impermeable <br /> cohesive soil (CL) to minimize water infiltration into bacl�ill. Surface water run-off must be directed <br /> away from buildings and structures. Landscaped surfaces within 10 feet of buildings and <br /> structures must have at least 10 percent drainage grades, while impervious surtaces within this 10 <br /> feet must have at least 2 percent drainage grades. Roof water nm-off must be permanently <br /> controlled with roof drains and downspouts discharging on long splash blocks or into subsurface <br /> pipes that discharge far from buildings and structures. Additionally, review concepts and <br /> recommendations in the WATERPROOFING section. <br /> Allied Projed 05039 12 July 31, 2005 <br />