Pennsylvania Statutes Title 52 P.S. Mines and Mining § 70-605. Surface explosive magazine requirements

(1) Reasonably bulletproof and constructed of incombustible material or covered with fire-resistive material. The roofs of magazines so located that it is impossible to fire bullets directly through the roof from the ground need not be bulletproof, but where it is possible to fire bullets directly through them, roofs shall be made bullet resistant by material construction, or by a ceiling that forms a tray containing not less than a four inch thickness of sand, or by other methods.

(2) Provided with doors constructed of three-eighth inch steel plate lined with a two inch thickness of wood, or the equivalent.

(3) Provided with dry floors made of wood or other non-sparking material and have no metal exposed inside the magazine.

(4) Provided with suitable warning signs so located that a bullet passing directly through the face of a sign will not strike the magazine.

(5) Provided with properly screened ventilators.

(6) Equipped with no openings except for entrance and ventilation.

(7) Kept locked securely when unattended.