NCKRI Symposium 2: Proceedings of the Thirteenth Multidisciplinary Conference on Sinkholes and the Engineering and Environmental Impacts of Karst
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University of South Florida
pg(s) 27-36 Karst can cause a litany of problems for a windpower project, and it is good practice to evaluate karst risk before proceeding with a proposed project. Windpower projects involve widely-spaced structures with small footprints that can cost $2 million to $5 million each. Financial viability can prove difficult, so it is important to find useful, inexpensive procedures for evaluating karst risk. The karst-risk-review process we have used can be split into the two categories outlined below. Desktop studies: * Search for relevant literature * Review aerial-photo and map, and analyze lineament * Search for existing well and boring logs * Survey local experts-landowners, U.S. Geological Survey, state geological survey, cavers, etc. Field studies: * Perform site reconnaissance * Conduct pit tests if bedrock is shallow * Drill-A normal geotechnical investigation includes one boring per turbine, while karst investigations may include multiple borings per turbine * Use a downhole camera-May be useful in evaluating extent of voids and convincing clients of risk. * Conduct geophysical studies Effectively communicating with developers is critical. They want to know the location of the problem sites and may ask, If there is a cave, what is the chance that a turbine will fail? The geo-professional needs to do the following effectively: * Explain the short-term (collapse) and long-term (settlement) risks, and mitigation options * Explain the uncertainty * Negotiate liability * Costs of investigation and mitigation * Get developers to determine how much to spend while understanding how much incremental-risk reduction they will receive The discussion of karst risk should be ongoing and investigations may proceed on a step-by-step basis as new information is gathered. It's important to determine whether to investigate all sites underlain by a potentially karstic unit or try to rank the sites based on risk before focusing the investigation on those with potentially higher risk. Per-turbine karst investigation costs can easily reach $20,000 and more, so investigating each site in a 100-turbine development can be a significant commitment. When possible, start karst evaluation early, manage available cash with a stepwise approach, and communicate. Open Access - Permission by Publisher See Extended description for more information.
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Conference Proceedings; Serials
Bangsund, William J. and Johnson, Kenneth S., "Evaluating karst risk at proposed windpower projects NCKRI Symposium 2: Proceedings of the Thirteenth Multidisciplinary Conference on Sinkholes and the Engineering and Environmental Impacts of Karst" (2013). KIP Talks and Conferences. 51.