Within any floodable area, any flammable, explosive or toxic materials in excess of quantities for normal household or janitorial use and which are allowed to be stored in the zoning district in which the storage is located, shall be elevated to the base flood elevation plus three feet; except that storage tanks containing liquids or gases may be located below the base flood elevation if:

    1. The tanks are too heavy to float or they are anchored or buried so as to eliminate flotation; and

    2. They are floodproofed so as to prevent the entry of floodwaters or the leakage of material into floodwaters.  (Ord. S-36983, 1978).