463. When blasting on the surface:(1) a warning before a primary blast shall be given by means of a siren between 3 and 5 minutes before blasting and a second warning given 1 minute before blasting;
(2) following the blast, a sound signal giving workers permission to return to their places of work shall be given;
(3) where a worker must remain in the blasting area, the worker must be provided with a shelter that protects against fly-rock; the location, design or construction of the shelter must be certified by a certificate signed and sealed by an engineer;
(4) when blasting is carried out near a building, a railway line, a road or an electric power line, the blasting charge shall be controlled and a blasting mat placed on the blasting site; the mat must(a) be constructed and maintained so that no metallic part comes into contact with the explosives;
(b) be deposited but not slid into place; and
(c) when made of tailings, contain no single or aggregate particles having a diameter larger than 5 mm (0.2 in).