Keys Gate Charter High School
Homestead (Miami-Dade County), FL
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The project site lies in south Miami-Dade County with a characteristic marl (calcareous silt) overburden soil atop limestone bedrock. The initial geotechnical recommendations called for wholesale removal of the silt layer from within the planned building (structure) area. Subsequently, Dunkelberger was retained in a Value Engineering (V.E.) role to evaluate the initial recommendations and present, if appropriate, less expensive options for foundation support of the structures.
Dunkelberger completed field exploratory work to verify the depth, thickness, and consistency of the silt layer as well as to obtain an undisturbed tube sample for laboratory consolidation (compression) testing. The field and laboratory data indicated that the silt was stiff (highly over-consolidated) due to desiccation and therefore only nominally compressible within the projected range of foundation (spread footing) and floor slab loads. Dunkelberger concluded that removal of the silt layer was not necessary and that the building area could be adequately prepared using standard construction measures (stripping, proof-rolling and placing of well-compacted, granular pad fill). The V.E. results saved approximately $100,000 in earthwork costs and also accelerated the construction schedule.
Supplemental services by Dunkelberger, carried out by certified engineering technicians, included field observation and testing of earthwork, sampling and strength testing of structural concrete, and inspection of post-tensioning of the elevated floor and roof slabs.