B-1.1, r. 2 - Construction Code

Full text
8.60. A contractor or owner-builder may not install an aboveground tank used to store petroleum products, unless it has a dike to form a diked area around the aboveground tank or tank farm holding 5,000 litres or more.
To that end, the diked area that protects
(1)  one tank only must have a capacity sufficient to contain a volume of liquid at least 10% greater than the volume of the tank;
(2)  several tanks must have a capacity sufficient to contain a volume of liquid at least equal to the volume of the greater of
(a)  the capacity of the largest tank plus 10% of the aggregate capacity of all the other tanks; and
(b)  the capacity of the largest tank plus 10%.
In calculating the capacity of the diked area, the volume of the part of the tanks situated below the top of the dike must be included.
O.C. 220-2007, s. 1.