34. Every shelter under which residual hazardous materials are stored shall have at least 3 sides, a roof and a floor. The floor shall be impermeable, not liable to be attacked by the stored material and able to support that material. The floor shall rise on each side to form an impermeable basin able to hold the greater of the following volumes: 25% of the total capacity of all the receptacles stored therein and 125% of the capacity of the largest receptable.