GEOPHYSICAL INVESTIGATIONS FOR LEVEE SYSTEMS - KILLING SEVERAL BIRDS WITH ONE STONE

摘要

Geophysical investigations can be an excellent tool for building the foundation of anynew or existing levee system project. A wealth of data can be collected very quickly thatcan ultimately serve many purposes in the planning, design, and construction of leveeembankments. In recent flooding along the Missouri River, we learned that theinformation obtained can be an excellent tool for anticipating and designing under- andthrough-seepage control measures in levees, thereby reducing the uncertainty duringflood fighting events. Coupled with traditional geotechnical investigations (drillholes,corings, test pits), geophysical investigations can help to reduce overall project costs,both in the investigations themselves, and in the constructed project. This isaccomplished by “filling in the gaps” in geotechnical investigations and reducing theunknowns and risks associated with the unknown during system design and analysis thatcan lead to higher construction costs. This paper addresses the geophysical investigationsperformed to date for one project near Omaha, Nebraska and how that will be coupledwith future geotechnical investigations.Along with aerial imagery and soil information, geophysical profiles can often help toreveal part of the geologic history of a levee system. A solid understanding of thegeologic history affords the design team the ability to design the appropriate controls andappurtenances for levee systems that enhance the overall performance and reliability ofthe system by reducing uncertainty in the levee foundations. Included herein areexamples from two projects how this “toolbox” approach can reduce risk for designersand levee owners.Collectively, the cost savings, understanding and increased confidence that geophysicalinvestigations offer to levee systems reduces both the risk and uncertainty in thesesystems and is therefore a tool that can benefit every levee system operator and owner.Some examples of cost savings are given herein and more are being developed as theproject progresses.