Your project is not a Love Canal scenario at all. At Love Canal the leaching chemicals affected homes with basements within only several blocks area near the source.
When the truth of Love Canal came to light, the government, AKA the local school board, was the culprit. Hooker Chemical did all the latest toxic chemical containment, and more, in a proper clay lined, former canal. Their containment techniques of the 1950's are still valid and authorized by the EPA today. They enclosed it with clay and grew gras on the top to beautify. The local school board took the property by eminent domain over Hooker's strong objections, as a park. The problems started only when the school board dug a foundation for a school, again over Hooker's strong objections. Chemical engineers had done it right to start with, it was politics that messed it up.
What is ammonium perfluoractanoate? I can not find it as a chemical anywhere.
Is it ammonium "perfluorooctanoate", CAS Number: 3825-26-1? If so, the 8 hour exposure limit is TWA: - ppm 0.1 mg/m3 in Australia and TWA: - ppm 0.01 mg/m3 in Michigan. It is recognized as an air pollutant, per state of Washington, WAC 173-460-160, Class B toxic air pollutants.
I reviewed the web sites you named and found them to be very infromative. DuPont has the safest employees of any chemical company and better than 99% of all companies in the world by a factor of 100. DuPont's environmental policies match that concern for the community as well.
Tell them this is far from a Love Canal fisasco by the government. The 50 year history is most important as a background. There are some things that the plant might need to do to stop additional or increasing spreading of the chemical, but based on the best analysis by the EPA and DuPont, the mass health deteriation of Love Canal is not even close in your situation.
It does bear constant watching and diligence by all persons for changes, trends, etc. From what I read so far, DuPont is responding as a good neighbor should, and also is being proactive to control.
Your current response is certainly accurate and responsible for neither passing on wrong information, nor downplaying it, nor inflaming the situation. I would tell them to go to the websites you named, and stay in touch with the agencies involved, go to the meetings, register with the agencies as a concerned citizen, etc.
Good luck and be careful with mob histeria based on false rumors. Just like the false suburan myths you get on the eamil - check out the sources, to the details!