C04_Attachment 10 -Geotechnical Engineering Report.pdf

This is a soil and foundation investigation report for a USDA Sugarcane Research Facility located at Bull Run Road in Houma, Louisiana. The report was prepared by Gore Engineering, Inc. (soil and foundation investigations) and RMF Engineering, Inc. (consulting engineers) for the U.S. Department of Agriculture.

The investigation included six soil borings drilled to 50 feet depth (B-1 through B-6) during June 2005, with an additional boring (B-7) drilled to 90 feet in December 2006. Laboratory testing comprised natural moisture content, unit weight, unconfined compression, triaxial shear tests, and Atterberg limits analysis. The subsoil consists of layered clay and silty clay materials with varying stiffness, extending to approximately 50 feet depth, underlain by soft organic clay with wood content. Groundwater was measured at depths ranging from 1.5 to 4.2 feet below surface. The report recommends pile foundations for all structural loads including ground floor slabs due to fair bearing quality of near-surface soils and compressible underlying subsoils. For mat foundations, an allowable bearing capacity of 1,200 lbs/sq.ft. for square spread footings up to 6 feet wide and 1,000 lbs/sq.ft. for continuous wall footings up to 3 feet wide is provided, with estimated settlements of 3/4 to 1¼ inches for structural loads and 2 to 10 inches for fill and floor loads depending on fill thickness. Estimated single pile load capacities range from 5 to 12½ tons for timber piles 30 to 50 feet in length with a factor of safety of 2.0. The report addresses drag load considerations, group effects, pile driving specifications, and preloading recommendations to minimize differential settlements. Additional analysis provided recommendations for longer piles (60 to 85 feet) with load capacities of 16 to 23 tons to further reduce drag-load settlements when fill thickness exceeds 2 feet.