project manual-salt storage bldg-2002

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, � - - � AET #20-01080 - Page 11 , ' We recommend the fill be placed in thin lifts that are comparably matched to the type of equipment and to the type of soil used as fill. The compaction should be monitored at the time of earthwork , to evaluate that the required compaction levels are achieved. ' Foundations It is our judgment that the proposed building can be supported by conventional spread footings ' after the recommended corrective grading procedures. Because ttus will be an unheated structure, we recommend all foundations for the building be placed at a depth of 60" below surrounding ' grades for frost protection. ' Based on the soil conditions encountered at the borings, and the recommended fill compaction . levels, it is our opinion the foundations for the building additions should be designed based on an , ' e soil ressure of 2,000 pounds per square foot (psfl. It is our judgment this allowabl beann8 P ' design will include a factor of safety of about three against localized s'hear or base failure of the footings. We estimate that total foundation settlements should be 1 or less, and differential ' settlements should be about 'fz" or less for the conditions shown by the boring logs. , Exterior Backfill We recommend that all bacl�'ill which is placed below steps, sidewalks or exterior slabs be ' compacted to a minimum of 95% of the Standard Proctor maximum dry density. Fill placed in landscaped areas should be compacted to a minimum of 90%. Fill placed below pavement areas ' should be compacted to at least 95%, and to a minimum of 100% in the top 3' of the subgrade. Non-frost susceptible sand fill is recommended. ' ; The use of silty sands, clayey sands, and clays may re,sult in frost related movements which must , ' �: :: be considered. These soils are more difficult to work with and are more frost susceptible than sands. If clays, clayey sands or silty sands aze used, this may result in abrupt frost heaving of ' ' � . .