Cal. Code Regs. tit. 19 § 1572.50
The height of piles shall not exceed seven (7) bags or six (6) feet. The width of piles shall not exceed twenty (20) feet and the length fifty (50) feet except that where the building is of noncombustible construction or is protected by automatic sprinklers the length of piles shall not be limited. In no case shall the ammonium nitrate be stacked closer than thirty-six (36) inches below the roof or supporting and spreader beams overhead, nor shall it be stacked closer than thirty (30) inches from the storage building walls and partitions. Aisles shall be provided to separate piles by a clear space of not less than thirty-six (36) inches in width. At least one service or main aisle in the storage area shall be not less than forty-eight (48) inches in width.
Cal. Code Regs. Tit. 19, § 1572.50