Environmental Permitting, Special Topics in Environmental Management

EPA’s Proposed UST Rules – Phase Out of Vapor and Groundwater Monitoring

EPA has proposed to phase out vapor monitoring and groundwater monitoring as methods of release detection for tanks and piping within five years of rule implementation.

What is vapor and groundwater monitoring?

Monitoring for vapors in the soil and for product in groundwater must meet EPA regulation 40 CFR 280.43.

Vapor monitoring. Vapor monitors sense and measure product vapor in the soil around the tank and piping to determine the presence of a leak. This method requires installation of carefully placed monitoring wells. Vapor monitoring can be performed periodically using manual devices or continuously using permanently installed equipment.
Groundwater monitoring. Groundwater monitoring devices sense the presence of liquid product floating on the groundwater. This method requires installation of monitoring wells at strategic locations in the ground near the tank and along the piping runs. To discover if leaked product has reached groundwater, these wells can be checked periodically by hand or continuously with permanently installed equipment. This method is effective only at sites where groundwater is within 20 feet of the surface.

Why is EPA phasing out vapor and groundwater monitoring?

EPA is proposing to phase out these two external release detection methods because these methods detect releases only after they enter the environment, compared to interstitial methods that monitor the space between the tank and piping walls and detects a release before it reaches the environment.

In addition, there are inherent problems with installing and confirming proper use of these methods. As methods of release detection, they are less protective of the environment than others. Regulators inspecting UST systems report common problems they encounter when inspecting UST systems using vapor or groundwater monitoring methods, such as an insufficient number of wells or wells improperly located to sufficiently monitor for potential releases.

Many UST facilities do not have site assessments that confirm whether site conditions support use of vapor monitoring and groundwater monitoring release detection. In instances when site assessments are available, they are often not thorough enough to verify whether regulatory requirements are met. Without site assessments, regulators are unable to determine whether site conditions are met. Reassessing sites to verify if site conditions support use of vapor monitoring or groundwater monitoring is intrusive and costly.

EPA is in the process of reviewing stakeholder comments to gain additional information in considering the significant impact on UST owners/operators. Although EPA anticipates a late 2013 final rule, the final rule still has to go through the Office of Management and Budget (OMB) review before it is finalized.

Stakeholder Comments

Many stakeholders believe further study is necessary to identify the population of tanks that may be impacted by the phase out of vapor and groundwater release detection methods. An anonymous public comment suggested requiring UST facilities to stop using vapor and groundwater monitoring in three years (instead of the proposed five years) in conjunction with the other rules being phased in. 

Iowa DNR

Iowa DNR agrees with the phasing out of vapor and groundwater monitoring as it has been practiced since the current regulations went into effect in the 1980s.  These methods have been unreliable for detecting a release within 24 hours. However, UST technology and equipment design have changed over the years. Iowa does not want to rule out the effectiveness of more accurate vapor monitoring such as practiced by certain vendors who are able to detect vapor releases quickly and accurately. These methods feature an array of vapor monitoring wells such that the entire UST system is monitored for releases smaller than 0.1 gallon per hour.  When installed during construction of the UST system, they can detect vapor releases before the system is activated.


The Association of State and Territorial Solid Waste Management Officials (ASTSWMO) is an association representing the waste management and remediation programs of the 50 states, five territories and the District of Columbia.  The ASTSWMO sought input from state tank programs in developing its comments. Frankly, the responses were all over the place!

EPA’s assumption that there are only 5 percent of active systems using vapor or groundwater monitoring to comply with release detection requirements varied from state to state.  Some states have implemented a prohibition on groundwater and vapor release detection, while others report above 20 percent use. For some states, this is the most cost-effective release detection, averaging $2,500 – $3,500 to complete site assessment and install 2 to 4 observation wells. Generally, the two monitoring methods are often used with other leak detection methods, including interstitial monitoring.

Dutch Oil Company

The Dutch Oil Company had concerns that the removal of groundwater monitoring wells as a form of leak detection leaves basically only two options for tank and line leak detection – automatic tank gauging (ATG) or statistical inventory reconciliation (SIR).

The company further claims that the requirement for ATG’s is a very expensive proposition to the industry and would not be viable to mid- to small-size stations where that type of investment would not be economically feasible. However, phasing out vapor monitoring wells should be phased out, since those results can be easily affected by many different situations, even events that occur aboveground, but not groundwater monitoring wells. It is also the groundwater monitoring wells that will show when there is a problem of leakage with the spill containment basins, when an ATG or SIR will not. The company suggested a "certification" for groundwater monitoring wells. The wells could be inspected for proper installation, slot positioning, depth, surface sealing, etc., then certified as reliable. Wells that don’t meet this requirement would then have to be replaced.



In addition to the phase out of vapor and groundwater monitoring, EPA is proposing that UST owners and operators perform annual operation and maintenance tests on electronic and mechanical components of their release detection equipment to ensure the equipment is operating properly.  Stay tuned for updates on any revisions to the proposed rules and continued discussions related to the impact the new UST rules will have on UST businesses.
Upcoming proposed UST rule topics may include deferral of field-constructed tanks, UST operator training, wastewater treatment tanks, and release reporting.
Also, see additional Environmental Daily Advisor reports related to EPA’s Proposed UST rules:

  • Walkthrough Inspections
  • Secondary Containment

Nancy W. Teolis, J.D., has been a Legal Editor for BLR’s environmental law publications since 1993, focusing primarily on underground storage tanks, pesticides, and hazardous waste-related requirements. Before joining BLR, she worked for the law firm Rudman & Winchell in Bangor, Maine, with an emphasis on asbestos exposure litigation.  She received her law degree from Western New England University School of Law in Springfield, Massachusetts, and is a member of the Connecticut bar.


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