ARCHIVED REPORTS_1992-1993 - Laserfiche WebLink

Home Browse Search

File No. 20-3668-01 kn K L E I N F E L D E R January 7, 1993 (corresponding,46 proposed, new stormwater retention pond)to in,Borings BSI;and B-3. However, it is possible that groundwater conditions may change in the future due to variations in groundwater withdrawal, rainfall, construction activities or other factors not apparent at the time of our field explorations. All borings encountering groundwater were backfilled with bentonite clay. The above is a general summary of the soil and groundwater conditions encountered in the borings drilled for this investigation. More detailed descriptions of the soils encountered in the borings are noted on the Logs of Borings. All soils have been classified according to the Unified Soil Classification System which is described on Plate A-2 of the appendix. LABORATORY TESTING Laboratory tests were performed on selected samples obtained from the borings in order to evaluate the moisture, density, strength, and swell characteristics of the soils encountered. The tests consisted of Moisture Content and Dry Density Determinations, Unconfined Compression, and Atterberg Limits tests. In addition, two Resistance-Value (R-Value) tests were performed on a sample of the surface soils for use in pavement sections design. aThe results of the Moisture Content and Dry Density Determinations and Atterberg Limits tests are noted on the Logs of Borings at the corresponding sample locations and are summarized on Plate A-24 of the appendix. The -Value test results are presented on Plates A-21 and A-22 of the appendix. An Atterberg Limits test performed on the soil sample taken for Resistance-Value (R-Value) number 1 indicated the sample to be nonplastic. CONCLUSIONS AND ELCOhD42MATIONS Foundations In our opinion, the structures can be supported on spread or continuous foundations bearing on the existing soils or on properly placed Engineered Fill. We recommend that foundations for one-story structures extend minimum depths of 12 and 18 inches, respectively, below the lowest adjacent finished. soil subgrade, interior or exterior, whichever controls. The recommended minimum width of foundations is 12 inches. We anticipate that loose soils will be exposed at the bottom of the foundation excavations. In order to provide more uniform foundation support, we recommend that the soils exposed in the bottom of foundation excavations be mechanically compacted prior to placing reinforcing steel in the excavations. The recommended minimum degree of compaction is 90 percent of the maximum dry density as determined by the ASTM D-1557 test procedure, at a moisture content near optimum. If any extremely loose soil pockets are encountered, they should be overexcavated and recompacted as described in the "Site Preparation and Grading" section of this report. Copyright 1993 KteinfeWer, Inc. Page 4 of 11