(a) General spill and overfill control requirements.
  (1) Owners and operators of all new and existing underground storage tank (UST) systems shall ensure that releases of regulated substances due to spills and overfills do not occur.
  (2) Prior to regulated substances being transferred and deposited into a UST system, the owner or operator shall ensure that the available volume in the tank is greater than the volume of regulated substances to be transferred into the tank.
  (3) During the entire time that regulated substances are being transferred into a UST system, the owner or operator shall ensure that the entire transfer operation is continuously monitored by the person conducting the transfer. Except as provided in paragraph (4) of this subsection, such monitoring may be accomplished by either of the following methods.
    (A) The person conducting the transfer shall be physically present at or near the transfer point at all times during the transfer operation, and shall have an unobstructed view of the transfer point to observe the transfer and to abate any spill or overfill.
    (B) The person conducting the transfer shall be physically present at the facility at all times during the transfer operation, and shall monitor the transfer operation using a central monitoring station which is electronically connected to remote sensing equipment at each transfer point, where such equipment is designed to detect and prevent any spills or overfills.
  (4) When USTs are equipped with ball float valves in the vent openings (or with other similar flow restrictors) for the purposes of compliance with the overfill prevention equipment requirements of subsection (b)(2)(C) of this section, and when regulated substances are transferred into such tanks under pressure (other than routine gravity unloading from normal transport vehicles), the following requirements shall be met during the time that regulated substances are being transferred into the tank.
    (A) The person conducting the transfer shall be physically present at or near the transfer point at all times during the transfer operation, and shall have an unobstructed view of the transfer point to observe the transfer and to abate any spill or overfill.
    (B) The transfer hose connection shall be equipped with an appropriate back-pressure sensor that will automatically shut off flow into the tank when the pressure in the tank reaches the tank's allowable design pressure (typically five per square inch gauge).
  (5) The owners or operators shall assure that the installation and maintenance of all required spill and overfill prevention equipment, as well as the procedures used for the transfers of regulated substances to or from a UST system, are in accordance with codes or standards of practice developed by a nationally recognized association or independent testing laboratory such as:
    (A) National Fire Protection Association (NFPA) Standard 385, "Standard for Tank Vehicles for Flammable and Combustible Liquids." The transfer procedures described in NFPA Standard 385 or American Petroleum Institute (API) Recommended Practice 1007, "Loading and Unloading of MC 306/DOT 406 Cargo Tank Motor Vehicles" may be used to comply with this subsection.
    (B) API Recommended Practice 1007, "Loading and Unloading of MC 306/DOT 406 Cargo Tank Motor Vehicles," which also may be used to comply with paragraphs (2) and (3) of this subsection; or
    (C) API Recommended Practice 1621, "Bulk Liquid Stock Control at Retail Outlets," with further guidance on spill and overfill prevention.
  (6) The owner or operator shall assure that all spill and overfill prevention devices installed pursuant to subsection (b) of this section are maintained in good operating condition, and that such devices are inspected and serviced in accordance with the manufacturer's specifications. In addition, the devices shall be monitored or tested in accordance with the requirements in §334.48(g) and (h) of this title (relating to General Operating and Management Requirements).
  (7) In the event a release of regulated substance(s) occurs due to a spill or overfill, the owner or operator shall comply with the release reporting, investigation, and corrective action requirements in Subchapter D of this chapter (relating to Release Reporting and Corrective Action).
(b) Spill and overfill prevention equipment. Except as provided in paragraph (4) of this subsection, all UST systems shall be equipped with spill and overfill prevention equipment which shall be designed, installed, and maintained in a manner that will prevent any spilling or overfilling of regulated substances resulting from transfers to such systems, as provided in this subsection.
  (1) Compliance schedule. All UST systems shall be in compliance with the equipment provisions of this subsection from the time of installation through the entire operational life of the system.
  (2) Equipment required. UST systems shall be equipped with each of the following spill and overfill prevention equipment or devices.
    (A) Tight-fill fitting. The fill pipe of the tank shall be equipped with a tight-fill fitting, adapter, or similar device which shall provide a liquid-tight seal during the transfer of regulated substances into the tank.
    (B) Spill containment equipment. The fill tube of the tank either shall be equipped with an attached spill container or catchment basin, or shall be enclosed in a liquid-tight manway, riser, or sump, and such equipment shall meet the following requirements.
      (i) The spill containment device shall be designed to prevent the release of regulated substances to the environment when the transfer hose or line is detached from the fill pipe.
      (ii) The spill containment device shall be equipped with a liquid-tight lid or cover designed to minimize the entrance of any surface water, groundwater, or other foreign substances into the container.
    (C) Overfill prevention equipment. Each tank shall be equipped with a valve or other appropriate device that shall be designed to either:
      (i) automatically shut off the flow of regulated substances into the tank when the liquid level in the tank reaches a preset level which shall be no higher than the 95% capacity level for the tank;
      (ii) automatically restrict the flow of regulated substances into the tank when the liquid level in the tank reaches a preset level which shall be no higher than the 90% capacity level for the tank, provided that such flow restricting device shall also alert the person responsible for the delivery when such preset level is reached. Flow restrictor devices may not be used when overflow prevention is installed or replaced on or after September 1, 2018; or
      (iii) emit an audible and visible alarm capable of alerting the person responsible for the delivery when the liquid level in the tank reaches a preset level which shall be no higher than the 90% capacity level for the tank, provided that the tank is also equipped with a valve or other device which is designed to automatically shut off or automatically restrict the flow of regulated substances into the tank when the liquid level reaches a preset level which shall be no higher than the 98% capacity level for the tank.
  (3) Design and installation requirements.
    (A) All spill and overfill prevention equipment shall be installed in accordance with the manufacturer's instructions and a code or standard of practice developed by a nationally recognized association or independent testing laboratory.
    (B) All underground components of the spill and overfill prevention equipment which are designed to contain regulated substances shall be properly protected from corrosion in accordance with the applicable provisions in §334.49 of this title (relating to Corrosion Protection).
    (C) The surfaces of all spill and overfill prevention equipment which are in direct contact with regulated substances shall be constructed of or lined with materials that are compatible with such regulated substances.
    (D) When installing the overfill prevention equipment specified in paragraph (2)(C) of this subsection, appropriate extension devices shall be utilized as necessary to assure that the shut-off or restriction of flow into the tank is achieved at the specified preset levels, which shall be based on the manufacturer's capacity charts for the size, dimensions, and shape of the tank.
  (4) Exceptions. UST systems are not required to be equipped with the spill and overfill prevention equipment prescribed in this subsection if one or more of the following conditions are applicable to such system:
    (A) the transfers of regulated substances into the UST system do not exceed 25 gallons per occurrence; or
Cont'd...