I'll offer one additional piece of insight on that. The federal contaminated sites action plan, which has been in place since 2005, has led to, especially in its early years, a comprehensive effort on the part of federal departments, agencies and real property landowners to identify potentially contaminated sites. We refer to them as “suspected.”
The process is to work through those potential sites to understand whether there is, in fact, contamination and whether it exceeds guidelines, and then work through planning and cleaning up those sites.
There's been a pretty comprehensive effort going back many years to identify potential sites. It's not to say there aren't any uncertainties left, but it has been pretty comprehensive. As an example, the program, when it started, was estimating in the range of 6,000 contaminated sites. It's now over 24,000, with the large majority of those—over 18,000—now closed. In many cases, they were closed once it was determined that the site was not, in fact, contaminated, so it was purely suspected.