Tank enclosures are optional and shall be designed and constructed by the Owner / Contractor. For a solid CMU wall enclosure, the enclosure wall shall be ventilated using air inlets and outlets, the bottom of which shall not be more than 6 inches above the floor, and shall be arranged to provide air movement across the floor as uniformly as practical and in accordance with the following:
When natural ventilation is used, each exterior wall up to 20 ft. in length shall be provided with at least one opening, with an additional opening for each 20 ft of length or fraction thereof. Each opening shall have a minimum size of 50 sq. inches and the total of all openings shall be at least 1 sq. inch per 1 sq. ft. of floor area.