Proposed Amendments To Engine Test Cells/Stands National Emission Standards For Hazardous Air Pollutants (NESHAP)

August 1, 2019

By: Farhana Momin

On April 26, 2019, EPA proposed to amend the 2003 NESHAP for Engine Test Cells/Stands. The rule applies to major sources of hazardous air pollutants (HAPs) that operate engine test cells/stands to test uninstalled internal combustion engines (ICEs) rated at 25 hp (19 kW) or higher. EPA proposed revisions after conducting a thorough technology assessment. During the assessment, risks due to air toxics from this source category were found to be acceptable. Further, EPA determined the current NESHAP provided a sufficient margin of safety to protect public health. No new cost-effective controls were identified. Therefore, EPA is not proposing any revisions to the numerical emission limit based on this review.

EPA will also retain the exemptions that apply to new or reconstructed test cells/stands used to test combustion turbine engines and all existing sources at a major HAP source facility.

Proposed Changes 

  1. SSM Plans: EPA proposed revisions to the SSM provisions to ensure they are consistent with a Court decision (Sierra Club v. EPA, 2008) that occurred since the initial publication of the Engine Test Cells/Stands NESHAP. In this Court decision, EPA vacated the SSM exemption. Consistent with this ruling, standards in this NESHAP will now apply at all times.
    • SSM Plans: Facilities will no longer need to develop an SSM plan or keep it current.
    • SSM Deviation Reporting: Facilities will no longer be required to submit periodic SSM reports as a stand-alone report since there will no longer be SSM plans. Deviations from applicable standards are still required to be reported in the Semiannual Compliance Report as already required under this rule.
  2. Emission Limits and Monitoring Requirements: Current emission limits and monitoring requirements of 40 CFR part 63, subpart PPPPP will now be applied to previously exempted periods of startups and shutdowns.
    • Concentration Limitation: Currently a 20 ppmvd (corrected to 15% O2) limit for CO or THC emissions applies when testing ICEs rated at 25 hp or more. This limit will now apply to periods of startup and shutdown as well.
    • Percent Reduction Limitation: A reduction in CO or THC concentrations of greater than 96% (corrected to 15% O2) will now be expected during all periods of operation, including during periods of startup and shutdown.
    • Monitoring Requirements: Currently the Engine Test Cells/Stands NESHAP requires thermal oxidizer or catalytic oxidizer operating temperature and other add-on control device operating parameters to be recorded at least once every 15 minutes. The operating limits will now apply to all periods of operation, including during periods of startup and shutdown.
  3. Electronic Reporting: Facilities will now be required to make electronic submittal of semiannual compliance reports, performance test reports and performance evaluation reports through EPA’s Central Data Exchange (CDX) using the Compliance and Emissions Data Reporting Interface (CEDRI).

Compliance Dates

Facilities are expected to comply with the revisions no later than 180 days after the effective date of the final rule. We will update this article with the effective date once the final rule is issued. Until then, facilities are expected to comply with the current requirements of 40 CFR part 63, Subpart PPPPP.

Relevant Links

EPA Site:

Federal Register Notice:

If you have questions regarding the Engine Test Cells/Stands NESHAP, please contact your EPS consultant.

Farhana Momin, P.E.
Project Engineer
Farhana’s primary area of practice is in the environmental compliance field, with a focus on air quality. Her air quality-related projects include the preparation of air compliance reports, Title V/SIP air permit applications, semiannual reports, and responses to proposed enforcement actions for clients in a variety of industries.

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