Requirements for Emergency Power Generator UST Systems
Written by: Brian Pottebaum, Director of Training Services
Emergency Power Generator systems are not always obvious since they are not typically installed in areas visible to customers. However, these generator systems are important and necessary to provide power to the building or structure in the event of power loss. These systems are typically found at hospitals and clinics, hotels, data storage centers, cell towers, college campuses, and large building complexes.
Along with many of the underground storage tank regulatory changes that EPA rolled out in 2015, Emergency Power Generator UST systems have become more regulated, specifically managing the system for petroleum leaks and releases. These changes affected existing systems, old and new, as well as those to be built in the future. The service companies as well as the facility operator need to be aware of these changes.
In addition to compliance with the UST regulations, various fire code requirements apply to power generator systems which owners and operators must consider and address. The following information is summarized from the EPA document Federal UST Requirements for Emergency Power Generator UST Systems (EPA-510-K-22-003).
Previously
These UST systems were mostly regulated under state and federal regulations promulgated in 1988, however they were not required to keep monthly records of release detection. EPA deferred the release detection requirement because at that time generator UST systems were often located at unsupervised stations in remote areas, which made monthly monitoring unworkable.
Present Time
Technology and monitoring equipment have improved drastically since the first draft of UST regulations, and as a result the EPA lifted the deferral on release detection for generator tanks. Additionally, EPA determined that when the rule was changed in 2015, approximately 30% of the active generator systems were already performing a method of release detection. Systems were being monitored in large part because many state UST implementing agencies did not defer them from the release detection requirement.
The System
Generators that supply emergency backup power to the intended facility are supplied fuel through some type of storage tank and delivery system while they operate. The petroleum storage tanks can be located aboveground as well as underground and can range in size depending on what the architectural and engineering needs are, but in any case, the system must work properly when called upon. Some other unique system features include return product piping, day tanks, and sub-base tanks, also called belly tanks. Pipe runs contain underground and aboveground piping that can have access points or containment sumps at (UST) tank top connections, building entry, and transitions from underground to aboveground. Access to the tank tops and piping is important for periodic inspection and testing.
Regulated Components
According to EPA, a UST system is one or a combination of tanks, including the underground piping, that contain an accumulation of a regulated substance. This includes underground ancillary equipment and containment system if any. EPA defines ancillary equipment as any devices, including, but not limited to, items such as piping, fittings, flanges, valves, and pumps used to distribute, meter, or control the flow of regulated substances to and from the UST. The power generator and other aboveground components, such as standalone filtration or polishing units, are not subject to the UST regulations. However, smaller aboveground storage tanks connected to the UST system, such as day tanks and belly tanks, are included and must meet all applicable federal UST requirements.
New Release Detection Requirements for Generator UST Systems (Installed on or before October 13, 2015* must achieve and maintain compliance by October 13,2018. Also, systems installed between October 13, 2015 and April 11, 2016 must achieve and maintain compliance with release detection at installation.)
- Determine and implement approved method of tank/ piping monthly release detection.
- RECORDS MUST BE UPDATED EVERY MONTH, example would be ATG printouts
- Notify the local authority having jurisdiction (AHJ) of release detection methods being used.
- If pressurized piping, underground system must be equipped with an automatic line leak detector (ALLD) or automatic interstitial monitoring (AIM).
- If suction piping (does not include safe suction), underground system is equipped with approved monthly monitoring or conduct a line tightness (0.1 gph) every 3 years.
- Release detection components, such as monitors, probes, and sensors must be tested annually for proper operation and programming (if applicable).
- If piping is part of a secondary containment monitoring system and used as monthly release detection method, containment sumps must be (liquid) tightness tested every three years.
- If using Vapor or Groundwater Monitoring (although not very common methods), maintain a record of a site assessment for as long as the method is used.
New Release Detection Requirements for Generator UST Systems (Installed after April 11, 2016 must achieve and maintain compliance with secondary containment requirements at installation.)
- All UST and piping systems must be double walled with integrated secondary containment and interstitial monitoring system.
- Implement interstitial monitoring of tank/ piping for monthly release detection.
- RECORDS MUST BE UPDATED EVERY MONTH, example would be sensor status printouts
- If pressurized piping, underground system must be equipped with an automatic line leak detector (ALLD) or automatic interstitial monitoring (AIM).
- If suction piping (does not include safe suction), underground system is equipped with secondary containment and interstitial monitoring system.
- Release detection components, such as monitors, probes, and sensors must be tested annually for proper operation and programming (if applicable).
- Piping is part of a secondary containment monitoring system and used as monthly release detection method, containment sumps must be (liquid) tightness tested every three years.
*October 13, 2015 is the federal deadline for secondary containment and applies to states that do not have UST program approval, however several states have different deadlines based on the date that state adopted the new regulations. For example, in Iowa the secondary containment deadline is November 28, 2007.
Because emergency power generator systems are typically used in critical situations, they need to function properly for an unknown amount of time when the municipal power source is lost. This could be inhibited if the release detection system responds to an alarm by shutting down the system or significantly restricting the flow of fuel to the generator. To prevent emergency power from being disrupted, EPA has allowed an alternative monitoring method on these systems. EPA strongly recommends owners and operators use an electronic line leak detector that sounds an alarm instead of restricting or shutting off flow of product to the day tank. These systems should not use mechanical line leak detectors because they function by restricting product flow.
For all pressurized piping systems associated with generator UST systems, regardless of the date of installation of the piping system, EPA recognizes the use of an “AIM” system as an option to meet piping release detection requirements. Like standard release detection systems, AIM requires monthly documentation indicating that the system is in normal status or not in alarm, which is usually done during the 30-day walkthrough inspection. Additionally, a history of this monthly documentation must contain the most recent 12 months at a minimum, along with annual or 3-year functionality testing of the release detection components.
Automatic Interstitial Monitoring (AIM) systems are secondary containment systems that include piping and all connected containment sumps, such as submersible turbine pump, transition, collection, and detection containment sumps. The piping and containment sumps must be approved for use, installed properly and compatible with fuels stored in the UST system. There are three categories of AIM systems and an audible or visual alarm notifies of a breach in any of these systems.
- Category 1 is a pressure or vacuum This system monitors for the change of either pressure or vacuum levels within the interstice. This system continually monitors the integrity of both the inner and outer walls of double-walled piping.
- Category 2 is a liquid-filled system that monitors changes in the level of a liquid such as brine or propylene glycol solutions within the reservoir holding the interstitial liquid. This system also continually monitors the integrity of both the inner and outer walls of double-walled piping.
- Category 3 is a dry interstice This system uses float-based or other type sensors typically located in containment sumps to monitor dry interstitial spaces that are used for piping interstitial monitoring. Category 3 AIM system uses liquid-detecting sensors to monitor for a leak through the inner wall. A breach of product through the primary wall is conveyed through the interstice to the containment sump where it contacts the sensor.
EPA regulation [40 CFR § 280.40(a)(4)] requires a release detection method on an UST system that meets their release detection performance requirements. There are many variations among individual UST site conditions and system configurations in the regulated community. Because of these variations, a complete AIM system would have to be manufactured and installed onsite as a unit to meet the release detection method requirements. AIM systems are comprised of several components. No one component manufacturer can verify that applicable regulatory performance requirements can be met for the entire system. UST system owners and operators can use the Certification of Compliance Form (on page 14 of Owner and Operator Introduction: Automated Interstitial Monitoring Systems for Underground Pressurized Piping on EPG UST SystemsEPA-510-K-22-001) to verify that their AIM systems meet design and installation criteria.
For the complete guide and more information regarding Emergency Power Generator regulations, refer to Federal UST Requirements for Emergency Power Generator UST Systems (EPA-510-K-22-003) and National Fire Protection Association (NFPA) 110: Standard for Emergency and Standby Power Systems at www.nfpa.org/NEC/electrical-codes-and-standards/NFPA-110?code=110.