Q-2, r. 32 - Regulation respecting hazardous materials
69. Every underground tank not to be subjected to overhead vehicular traffic shall be sunk
(1) to a depth of at least 60 cm below the natural ground surface and be covered with materials referred to in section 67; or
(2) to a depth of at least 40 cm, be covered with materials referred to in section 67 and be covered with a slab of reinforced concrete at least 10 cm thick.