# COMAR Title 26 — Department of the Environment

## Subtitle 10 — Oil Pollution Control and Storage Tank Management

### Chapter 17 — Shop-Fabricated Aboveground Storage Tanks

#### Regulation .04 Performance Standards for Vaulted Shop-Fabricated ASTs.

*COMAR 26.10.17.04*

An owner, an operator, and a person in charge of an AST system that installs a shop-fabricated AST in a vault shall:

A. Construct a UL listed vault;

B. Ensure the vault and the vaulted AST comply with the design, construction, installation, and operation requirements of:

  (1) This regulation;

  (2) NFPA 30 “Flammable and Combustible Liquids Code”;

  (3) If the vaulted AST is used as part of a motor fuel dispensing facility, NFPA 30A “Code for Motor Fuel Dispensing Facilities and Repair Garages”; and

  (4) NFPA 70 “National Electrical Code” for all electrical wiring;

C. Ensure the vaulted AST is:

  (1) UL listed for aboveground use and for the type of product being stored;

  (2) Completely enclosed in the vault; and

  (3) Not partially or entirely covered by backfill;

D. Provide venting for the vault and the vaulted AST according to the following requirements:

  (1) If the AST stores a Class I liquid, vent the vault in accordance with NFPA 30 “Flammable and Combustible Liquids Code”;

  (2) Terminate a normal vent for the vaulted AST:

    (a) Outside of the vault;

    (b) At least 12 feet above ground level; and

    (c) At least 5 feet from a building opening;

  (3) A normal vent for the vaulted AST may not terminate in a location that allows vapors to be trapped by the eaves of a building;

  (4) Ensure that an emergency vent for the vaulted AST is vapor-tight and allows for the venting of vapors inside of the vault; and

  (5) Do not use a long-bolt manhole cover as an emergency vent for the vaulted AST;

E. Install vapor and liquid detection systems in the vault that meet the following requirements:

  (1) The vapor detection system:

    (a) Is equipped with an on-site alarm that has a battery backup;

    (b) Has vapor detectors located not higher than 12 inches above the lowest point in the vault; and

    (c) Is set to alarm when vapors reach or exceed 25 percent of the lower flammable limit of the oil stored;

  (2) The liquid detection system is:

    (a) Set to alarm upon detection of a liquid; and

    (b) Located in accordance with the liquid detection system manufacturer’s instructions; and

  (3) The vapor and liquid detection systems required under §E(1) and (2) of this regulation are designed so that if either system alarms, a signal alerts the owner, the operator, and the person in charge of the AST system:

    (a) At a constantly attended location where the vaulted AST is located; or

    (b) At another location that is continually monitored; and

F. Ensure the vaulted shop-fabricated AST complies with the spill and overfill prevention requirements in Regulation .08 of this chapter.