923 100TH ST SE 2018-01-02 MF Import

UPS November 12, 1978 Page Two material was removed from the site. In the deepest area to be backfilled several minor seepages were exposed during the excavation of unsuitable soils. These we, a first covered with 4" - 6" (size) cobbles and then received a lift o, imported clean sand. Native materials used for backfill Included: Brown, gravelly silt and sand (A); and gray, silty gravel and sand (B). For use in the more moist, low areas of the site, gray line sand (C) was imported and placed before further backfilling proceeded. With the arrival of wet weather, the contractor opted to fill the area directly under the building site with imported clean sand (E) to bring that portion of the site up to grade. After a site visit by Tom Bekey, Chief Geologist, the storm sewer contractor began using an impoi ted silty, gravelly sand (D) and clean sand (E) for trench backfill to achieve required compaction. The maximum dry densities (ASTM:D-1557-70T) of the respective materials were: (A) 110 PCF @ 11% optimum moisture (B) 126 PCF @ 10 % optimum moisture (C) 110 PCF @ 10% optimum moisture (D) 132.5 PCF @ 8% optimum moisture (E) 120.5 PCF @ 13% optimum moisture Specifications required that the fill material be compacted to at least 95% of ASTM:D-1557 (AASHO:T-180). On November 4 however, the requirement was lowered to 92%. The in -place density test locations may be seen on the Site Plan, Plate 1. The following are the test results: