Before the US builds any more wind projects, we must be sure that these projects will be properly decommissioned at the end of life. Otherwise we risk a country littered with huge rusting eyesores.
Wind turbine projects may not be required to decommission wind projects and remove wind turbines and towers at the end of life and to return the site back to its pre-existing state (i.e., demolish the tower and the substantial foundation).
Even if there are expectations that this decommissioning and remediation will take place, there may not be a requirement for the project developer/owner to provide funds for decommissioning the project at the end of plant life.
It is also important to understand that the "economic life" of a wind project may be shorter than you think. Project economics are driven by tax and renewable credits that are not permanent. Wind project capacity factors (and profits) may be far below expectations, leading these projects to be abandoned when expenses for maintenance are greater than profits.
Some states, the BLM and some savvy land owners require wind project developers to provide funds or guarantees to fund the decommissioning of the project, but many wind projects have no decommissioning fund requirements.
In some cases, wind developers assert that the salvage value of the plant would be more than enough to pay for decommissioning. But a more careful look at these assertions may reveal signficant shortcomings - see this study: Wind decommissioning fund study
In other situations, a wind developer must make representations that the money for decommissioning will be available when needed. The project may change hands multiple times and the owners may decide that bankruptcy is preferable to paying for decommissioning after all the profits are long gone.
The forest of unsightly abandoned wind generators in Southern California are evidence that without comprehensive wind project decommissioning requirements the US may be littered with abandoned wind tubines.
Late addition: Ghost turbines