B-1.1, r. 2 - Construction Code

Full text
8.128. The intake end of a fill pipe or gauge pipe installed on an underground tank must have a tight-fitting cap.
It must also be protected against vehicle impact by at least one barrier if the pipe extends above ground level.
If the intake end of a fill pipe or gauge pipe is below or at ground level, it must be protected by a box with a cover made of metal or concrete that prevents any transmission of surface loads to the tank.
O.C. 220-2007, s. 1.