Laserfiche WebLink
Home Reflections <br />Project BABX-94-463 <br />October 26, 1994 <br />Page 2 <br />unacceptably high risk of structural distress due to differential settlement. We recommended <br />the disturbed, soft or loose sands, silts and clays be excavated and replaced with engineered <br />backfill to provide a pad suitable for support of the house and garage. We also recommended a <br />smooth -bucket backhoe perform the excavating in order to minimize further disturbance of the <br />underlying natural but saturated soils. <br />Excavation to suitable soils was performed on July 1, 1994. Unsuitable soils were excavated to <br />depth from about 5 to 10 feet below existing site grades. Based on information we were <br />provided, this elevation was about 5 feet below the proposed basement footing elevation. <br />After unsuitable soils were excavated, the bottom soil observed was sandy lean clay glacial till <br />judged to be medium to rather stiff in consistency. <br />A minimum of 10 feet of excavation oversizing was provided beyond the proposed outside <br />edges of perimeter footings. Excavation oversizing was judged adequate. <br />Compaction Testing <br />Four compaction tests were performed in compacted backfill. Soil used as backfill was <br />imported poorly graded sand with silt. It was compacted using a smooth -drum roller. Results <br />of all compaction tests exceeded the recommended minimum of 95 percent of the maximum dry <br />density determined in accordance with ASTM Test Method D 698 (standard Proctor). <br />Compaction and Proctor test results are attached. <br />Conclusions <br />Our conclusions are based on the results of our excavation observations and compaction testing, <br />and information we were provided regarding the proposed construction. Based on this, it is our <br />opinion excavation bottom soils observed are suitable for support of backfill and the proposed <br />construction. It is also our opinion that adequate excavation oversizirg was provided. <br />Based on compaction test results, it is our opinion backfills were compacted to densities <br />exceeding the recommended minimum of 95 percent of standard Proctor density at the locations <br />and elevations of the tests. <br />General <br />Standard penetration test borings with power equipment were not authorized nor taken in the <br />building area to evaluate the soils at depth. However, the soils which were visible and the <br />