I'm glad to hear the story about the aluminum foundry proposing a non-chlorine process in response to a permit challenge. That is an intervention that I beleive will really result in changes, unlike many of the attempted permit interventions with already existing sites.
I don't know much about Title V permits. Water permits, which I know more about, are not Federalized, they are really mostly controlled by state agencies. In some of the states, they are enforced, in some, they are not. The ones in which they aren't tend to be the states that need additional environmental protection the most.
How does this get back to libraries? I would advise any librarian that decides to help the public with understanding/responding to permits to also review the enforcement stuation in their state. If you're going to direct people to permits, try to give them a realistic idea of what permits are likely to accomplish.