You might try your local military base, active or reserve.  I recall that a
number of years ago the University of Louisville's Photo Archives had some
nitrate film stock and OSHA made them store it in a suitable location rather
than the old warehouse they had it in.  Ft Knox was the only place in the
area that had a site with the required specifications, an unused ammunition
bunker.

Frank Thomson
Curator
Asheville Art Museum