1001 N BROADWAY Geotech Report 2018-01-02 MF Import

� � � � � � � � � � � � � J-736 Page 9 The suitability of excavated site soils for compacted structural fill depends,on the gradation and moisture content of soil when it is placed. Soils containing greater than about 5 percent fines (that portion of the soil passing a U.S. No. 200 sieve) becomes increasingly sensitive with changes in the moisture content, Ttierefore the specified compaction of the soil be- comes harder to r,btain unless the moisture content of the soil is strictly controlled and maintained near the optimum during placement. Grain size analyses conducted on repres�ntative samples of on site soils indicated that the SILTS contained from 50 to 100 percent fines and the FILLS contained from 28 to 35 percent fines indicating them to be extremely moisture sen- ` sitive. In our. opinion, the natural moisture content of these soils at the time of our explorations was above optimum for the SILTS, and at or near optimum for the GLACIAL TILLS. " Placement of these soils as structural fill would requir= drying of the soils prior to compaction to within 2 percent of the optimum n;oisture content. Because of the large area to be filled, we anticipate drying could be achieved by progressively spreading in thin lifts, disking, and subsequently compacting as optimum moisture contents are approached. It is important that these operations be accomplished during extended dry wea- ther periods, which would generally be late su�er to early fall months. During wet weather periods, drying of the soils would be impractical and compaction difficult to achieve, pos- • sibly resulEing in lengthly and costly construction delays. Should earth work activities be scheduled during the wet sea- son; we reco�end importing a clean, well graded, sand and gravel containing less than 5 percent fines for use as structural fill. S �