(a) Use, storage, handling and/or production of Regulated or Hazardous Substances in conjunction with permitted and conditional uses in this district shall be limited as to each use, to:
(1) The aggregate of Regulated or Hazardous Substances in use, storage, handling and/or production may not exceed 20 gallons or 160 pounds at any time.
(2) The total use, storage, handling and/or production of Regulated or Hazardous Substances may not exceed 50 gallons or 400 pounds in any twelve month period.
(b) Storage of fuel and lubricants for vehicle operations in conjunction with permitted and conditional uses in this district shall be in underground tanks placed above the floor surface of a below grade vault. Such tanks shall be of double-wall construction, and otherwise assembled and installed in accordance with applicable regulations. The vault shall allow access for physical inspection of the tank for leakage and the interior of vault shall be continuously monitored and alarmed to provide for automatic and immediate detection of any release from the tank.
(c) Notwithstanding other provisions of this section, non-conforming uses in this district presently utilizing underground storage tanks shall be permitted to replace existing tanks with those constructed as per the specifications of 1174.06(b) above, and not exceeding the capacity of existing tanks.
(d) No substitutions of a non-conforming use shall be permitted which results in an increase of the Hazardous Potential Ranking System on a parcel within this district. If the Hazardous Potential Ranking decreases for a non-conforming use for a period of twelve months or more, the non-conforming right to the higher Hazardous Potential Ranking shall be deemed to have been lost through non-use for that period of time.
(e) Heating fuels for residential use in tanks having a capacity of 500 gallons or less are exempt from this ordinance.