30 CFR § 75.1312 Explosives and detonators in underground magazines.
(a) The quantity of explosives kept underground shall not be more
than is needed for 48 hours of use.
(b) Except as provided in §75.1313, explosives
and detonators taken underground shall be kept in--
(1) Separate, closed magazines at least 5 feet apart;
or
(2) The same closed magazine when--
(b)(2)(i) Separated by a hardwood partition at least 4 inches
thick; or
(b)(2)(ii) Separated by a laminated partition; or
(b)(2)(iii) Separated by a device that is equivalent.
(c) Only explosives and detonators shall be kept in underground
magazines.
(d) Magazines shall be substantially constructed and all interior
surfaces shall be made of nonconductive material, with no metal or other
conductive material exposed inside.
(e) All magazines shall be--
(1) Located at least 25 feet from roadways and any source
of electric current;
(2) Located out of the direct line of the forces from
blasting; and
(3) Kept as dry as practicable.
(f) Magazine locations shall be posted with indelibly marked and
readily visible warnings indicating the presence of explosives.
(g) Only materials and equipment to be used in blasting shall be
stored at magazine locations.
