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Gus <br /> CONSTRUCTION CONSIDERATIONS <br /> OBSERVATIONS AND TESTING <br /> It is possible there are soil and water conditions on site that were not represented by the limited <br /> number of borings. Consequently, on-site observation and testing during construction are <br /> ' considered integral to the successful implementation of the recommendations within this report. <br /> We strongly recommend the excavation for the valve vaults be observed and tested by the <br /> tgeotechnical engineer prior to the placement of concrete. We also recommend that density tests <br /> be taken in any structural fill in order to document proper compaction is being achieved. <br /> t <br /> SOIL COMPACTION <br /> ' Based on visual classification and limited testing (plasticity characteristics), all of the soils <br /> encountered are suitable for use as trench backfill. However, higher plasticity CUCH silty clays <br /> ' and CH clays are subject to internal volumetric changes (shrinkage and swelling) as their natural <br /> moisture content fluctuates seasonally. To lessen these volumetric changes, we recommend <br /> ' that any higher plasticity soils be thoroughly blended with lower plasticity SC, MUCL, and CL <br /> soils. <br /> The soils' in-situ (natural, undisturbed) condition appears to vary from reasonably well-drained <br /> to saturated. Accordingly, their natural moisture contents vary from their estimated optimum, to <br /> ' six percent (6%) above optimum. At the time of placement and compaction, it is recommended <br /> that soil moisture contents be lowered so they do not exceed the optimum for the material by <br /> ' more than two percent (2%). This will not only ensure excellent compaction and high (cohesive) <br /> shear strength, it will also minimize the internal consolidation of the earthen fill. <br /> Adjustment (downward) of natural moisture content in cohesive soils may be accomplished by <br /> disking the fill prior to compaction. Obviously, good drying weather is essential for efficient filling <br /> and compaction operations. Therefore, construction operations may have to be limited to the <br /> more moderate spring, summer, or fall months. However, use of hydrated lime or kiln dust may <br /> be used to modify the soil characteristics or to aid in compaction, respectively, during periods of <br /> ' inclement weather when filling and compaction operations must proceed. <br /> Geotechnical Exploration for Sanitary Pipeline <br /> ' New Vulcan Waterline Pipeline, Decatur, Macon County, Illinois <br /> SKS Project No. 12-418885 Page 8 <br />