Is there any federal regulation that requires disposing of the HEPA-filter in a negative air machine at the end of a job?

No, there is not. There may be contractual requirements in specifications, but there is no regulation that addresses this practice. We used to discuss, in initial Contractor Supervisor training, the differences in high-capacity and standard 2 ft.by 2 ft. by 1 ft. HEPA filters for negative air machines, cost considerations, filter life and other issues related to this question. However, with the development of many new negative air machines that are no longer standard filter size, most of the issues mentioned are moot. Also, with the growth of the restoration contractor industry, many asbestos control projects are short, and equipment is moved from job to job. A contractor should be aware of the issues involved, but there are no regulations that address this issue.

Does AHERA regulate schools in prison facilities? How about k-12 home schools?

AHERA applies to public and private, not for profit k-12 schools (institutions or agencies that are accredited to issue diplomas upon completion of k-12 curriculum).

So, yes, AHERA applies to k-12 schools in juvenal detention facilities, the same as it would to a public school.

However, AHERA does not apply to k-12 home schools (private homes). EPA has always held to the interpretation that federal asbestos regulations (i.e., AHERA, NESHAP, MAP) do not apply to single residential homes.

The school has tested asbestos window caulk inside and outside of glazing. While the interior side needs to be in the AHERA inventory, does the outside also need the 3-year inspections?

With few exceptions, AHERA requirements apply only to the interior portions of school buildings. So, the technical answer is “no”. However, I am sure that in most cases, your client (the LEA) would want the same asbestos controls used whether inside or outside the building. The potential for civil liability (claims of exposure) is probably greater for the school than regulatory liability.