What’s is AHERA?

Asbestos Hazard Emergency Response Act (1986).

Are all schools required by law to have an AHERA Management Plan?

Yes.   Even schools (or school additions) that were built after July, 1988.

How long must I keep my AHERA documentation?

Documents must be retained forever.  Keep in mind that the district must appoint a "Designated Person" that is responsible for asbestos issues in the district.