1802 75TH ST SW 2021-12-30 - Laserfiche WebLink

-5- thousands of years ago. The unweathered glacial till consisted of very dense, silty fine to coarse sand with some fine to medium gravel. Wet soil conditions were noted in boring B-1 from 5.1 to 5.8 feet within a more sandy layer. Since there were no wet conditions noted in boring B-2, we believe that the observed wet conditions represent a perched groundwater condition. DISCUSSION AND RECOMMENDATIONS Site Preparation The on -site soils contain a significant percentage of silt which make them particularly sensitive to moisture with regard to trafficability and fill placement. These soils may degrade to a slurry -like consistency when sub- jected to construction traffic or are otherwise disturbed in wet conditions. The moisture content determinations from the boring samples indicate that the soils are most probably near or slightly above their optimum moisture content. Therefore, any grading which includes utilization of the on -site soil for foundation backfill should be accomplished in dry weather so that these soils can be dried slightly or maintained at their present moisture content during placement and compaction. If on -site excavated soils cannot be used during a period of dry weather, it will be necessary to import a clean granular material for backfilling foundations. Imported granular backfill should be free of organic and deleterious materials, and should satisfy the following gradation require- ments: Converse Consultants NW