According to utility documents filed by Xcel Energy for it's Nobles Wind facility, it will cost approximately $445,000 (in 2009 dollars) per turbine to decommission the wind facility. This means it would cost $532,000 per turbine (in 2019 dollars) for each of the 134 turbines in operation at this facility, bringing the total cost of decommissioning the Nobles project to $71 million. However, Xcel also stated these estimates were conservative, meaning this likely represents the high-end cost of decommissioning.
Other wind turbines have six-figure decommissioning costs, as well. According to utility documents for the Palmer's Creek Wind facility in Chippewa County, Minnesota, it would cost $7,385,822 to decommission the 18 wind turbines operating at that site, a cost of $410,000 per turbine.
One would think such a price tag would at least result in a thorough decommissioning job, but one would be wrong.
According to the Nobles Wind document, "Restoration activities will include and not be limited to removal of all physical material and equipment related to the project to a depth of 48 inches."
This means Xcel will only remediate the site to a depth of four feet, leaving most of the massive concrete foundations, which go as deep as 15 feet, used to anchor the wind turbines , in the ground indefinitely.