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Proper Monitoring Essential to Reducing ‘Fugitive Emissions' Under Leak Detection and Repair Programs

ChemAlliance Staff

Note:  The following article originally appeared as Volume 2, Number 9 of "Enforcement Alert" (EPA 300-N-99-014, October 1999).  Enforcement Alert is published by the US EPA Office of Regulatory Enforcement.  It appears here by permission of EPA.  Back issues are available at:

The Clean Air Act requires refineries to develop and implement a Leak Detection and Repair (LDAR) program to control fugitive emissions. Fugitive emissions occur from valves, pumps, compressors, pressure relief valves, flanges, connectors and other piping components. Comparison monitoring conducted by the U.S. Environmental Protection Agency's (EPA) National Enforcement Investigation Center (NEIC) shows that the number of leaking valves and components is up to 10 times greater than had been reported by certain refineries (see Table 1). EPA believes this great disparity between what refineries are reporting and what EPA is finding may be attributable to refineries not monitoring in the manner prescribed in 40 CFR Part 60, Appendix A, Method 21.

Federal regulations require refiners to routinely monitor for leaks and to fix any equipment found leaking. Failure to identify leaking equipment results in necessary repairs not being made and continuing fugitive emissions of volatile organic chemicals (VOCs) and other hazardous chemicals. EPA estimates that the failure to identify and repair leaks at petroleum refineries could be resulting in additional VOC emissions of 80 million pounds annually. VOCs contribute to ground-level ozone, a principal component of smog, which can cause significant health and environmental problems.

What the Law Requires

Specific requirements for refinery fugitive emissions are identified in 40 CFR Part 60, New Source Performance Standards (NSPS), and 40 CFR Parts 61 and 63, National Emission Standards for Hazardous Air Pollutants (NESHAP). Many State and local air agencies incorporate federal requirements but some have established more stringent requirements as authorized by law. The various regulations require refineries to implement an LDAR program to reduce fugitive emissions from valves, pumps, compressors, pressure relief valves, flanges, connectors, and other piping components.

Valves are usually the single largest source of fugitive emissions. Emissions from any single piece of equipment are usually small. Based on the large number of equipment components that can leak and are subject to LDAR requirements, however, cumulative emissions can be very large. To obtain a proper reading of emissions from leaking components the monitoring equipment must be calibrated correctly and held at the component interface where leakage could occur (e.g., at the seal between the valve stem and housing) for a sufficient length of time to obtain a valid measurement.

LDAR Programs Should Consist of Several Processes

LDAR programs are generally comprised of four processes. Regulations vary but usually require refineries to:

  • Identify components to be included in the program;
  • Conduct routine monitoring of identified components;
  • Repair any leaking components; and
  • Report monitoring results.

Compliance issues associated with each of these processes have resulted in numerous enforcement actions by EPA Regional offices, State agencies, or local air boards, depending on the specific regulations. Common violations include:

  • Failure to identify process units and components that must be monitored;
  • Failure to follow prescribed monitoring procedures;
  • Use of incorrect or expired calibration gasses;
  • Failure to repair components within specified timeframes; and
  • Failure to submit quarterly reports and maintain appropriate calibration and/or monitoring records.

Refinery Monitoring Reports; What EPA is Finding

During the past several years, NEIC has monitored for leaking components at refineries. For 17 facilities investigated by NEIC, the average leak rate reported by the facilities was 1.3 percent. The average leak rate determined by NEIC and confirmed by the facilities was 5.0 percent. One explanation for this difference in leak rates may be found in a report published by the Bay Area Air Quality Management District ("Rule Effectiveness Study"). The Bay Area Air Quality Management District determined that when valves were inspected at a distance of one centimeter (0.4 inches) from the component instead of at the interface with the component, as the regulations require, 57 percent of the leaking valves would be missed when monitoring above the 500 ppm level.

Fugitive emissions account for 22 percent of all emissions from non-refineries but account for more than 55 percent of all refinery emissions identified in the 1996 Toxic Release Inventory (TRI). Since TRI includes only "reportable" hydrocarbons, total fugitive emissions were significantly larger than the 33 million pounds then identified by reporting refineries.

The failure to identify leaks means that they remain unrepaired and will continue to release VOCs and hazardous substances into the atmosphere. Emission estimates using a 50/50 split between components in gas/light liquid service (see Table 1) suggest that these 17 refineries' annual fugitive emissions could be more than 6,000 tons per year greater than previously believed. Extrapolating this difference to all refineries larger than the smallest refinery investigated by NEIC also suggests that there may be an additional 80 million pounds of VOCs being emitted each year because refinery leaks are not being identified properly and repaired promptly, as required by LDAR programs. Significantly and as recognized by industry, fugitive emissions can be reduced by up to 90 percent if leaks are detected and repaired in a timely manner.

Regulatory Impacts of Inadequate Fugitive Monitoring

By not fully identifying all leaking components, refineries are likely causing the unnecessary release of excess hydrocarbons. The impacts of these additional hydrocarbon releases may result in:

  • Additional VOC emissions that could worsen local or transboundry smog problems;
  • Under reporting of fugitive emissions on the annual Toxic Reporting Inventory;
  • Under reporting of various TRI chemicals on annual Form R submissions; and
  • Delayed or denied permits for expansion.

Most LDAR regulations allow for decreased monitoring frequency if certain performance standards are consistently achieved. Monitoring frequency is decreased from quarterly to annual monitoring if less than two percent of the valves within a process unit are found leaking. Conversely, if greater than two percent of the valves are found to be leaking, monitoring must be conducted quarterly. EPA monitoring showing a greater than two percent leak rate has resulted in refineries reverting back to quarterly monitoring.

Improving Leak Detection Monitoring Reliability

Although not required under current LDAR programs, several practices appear to improve the reliability of monitoring data and LDAR compliance:

  • Energetic LDAR coordinators (advocates) with the responsibility and authority to make things happen;
  • Continuing education/refresher programs for plant operators. Plant operators can have a major impact on LDAR compliance;
  • Diligent and well-motivated monitoring personnel;
  • Use of a lower than required leak definition. Several refineries use a leak definition lower than the regulatory limit. For example, several refineries use a 500 ppm limit rather than the regulatory limit of 10,000 ppm;
  • More frequent monitoring than required. Rather than monitoring annually, some refineries monitor quarterly. More frequent monitoring also may permit lower emissions to be reported on the annual Toxic Reporting Inventory and/or Form Rs; and
  • Established Quality Assurance/Quality Control procedures. Several refineries have initiated a program to check the monitoring results submitted by the monitoring team (in-house or contractor).

EPA's Office of Enforcement and Compliance Assurance is encouraged by efforts currently underway by the National Advisory Committee on Environmental Policy and Technology (NACEPT) petroluem refining workgroup to find more cost-effective ways to identify significant leaks through new technology that allows for quick identification of the most significant losses. Meanwhile, however, the regulated industry is expected to comply fully with existing LDAR requirements.

Table 1.  Comparative Monitoring Results

Refinery Company Monitoring:


NEIC Monitoring:


Leak Rate:

Company / NEIC (%)

Emissions Rate: Company / NEIC (lb/hr) Potential Emissions:

Undetected Leaks (lb/hr)

A 7694/170 3363/354 2.3 - 10.5 38.8 - 106.6 67.8
B 7879/223 3407/216 2.8 - 6.3 44.0 - 73.5 29.5
C 3913/22 2008/108 0.6 - 5.4 18.3 - 90.1 71.8
D 2229/26 1784/24 1.2 - 1.4 15.5 - 17.1 1.6
E 5555/96 2109/112 0.7 - 5.3 50.7 - 125.8 75.1
F 42505/124 3053/53 0.3 - 1.7 154.7 - 382.3 227.6
G 14307/226 3852/236 1.6 - 6.1 122.2 - 369.7 247.5
H 20719/736 3351/179 3.6 - 5.3 332.2 - 469.7 137.5
I 5339/9 2754/84 0.2 - 3.1 16.9 - 76.6 59.7
J 8374/78 2981/55 0.9 - 1.8 50.8 - 78.5 27.7
K 6997/101 1658/114 1.4 - 6.9 56.1 - 201.2 145.1
L 12686/26 3228/125 0.2 - 3.8 34.9 - 84.0 49.1
M 4160/40 1926/222 1.0 - 11.5 25.7 - 192.2 166.5
N 5944/29 2487/106 0.5 - 4.3 26.1 - 112.3 86.2
O 7181/112 2897/130 1.6 - 4.5 60.8 - 140.9 80.1
P 8532/203 4060/181 2.4 - 4.5 98.8 - 167.5 68.7
Q 6640/36 2608/74 0.5 - 2.8 30.5 - 87.5 57.0
  170,717/2,266 47,526/2,372 1.3 - 5.0


1,177.0 - 2,775.5 1,598.5

A Note Regarding EPA Policies for Encouraging Industry Self-Policing

EPA has adopted two policies designed to encourage the regulated community to comply with environmental laws.

For more information, see EPA's Audit Policy Website at:, and the Small Business Policy at:

For More Information

Contact Ken Garing, National Enforcement Investigations Center, (303)236-6658;Email:; Tom Ripp, Office of Compliance, Manufacturing, Energy and Transportation Division, (202564-7003;Email:; or Jim Jackson, Office of Regulatory Enforcement, Air Enforcement Division, (202) 564-2002;Email:

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