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Proposed Air Quality Permit 7116-SC – Source Category Permit Operate Existing Natural Gas-Fired Emergency Engines

Friday, August 19, 2016


Proposed Air Quality Permit 7116-SC – Source Category Permit Operate Existing Stationary Natural Gas-Fired Emergency Engines Exempt from NSPS Subpart JJJJ, but Subject to NESHAP Subpart ZZZZ in the District of Columbia

Notice is hereby given that, pursuant to 40 C.F.R. Part 51.161, D.C. Official Code §2-505, and 20 DCMR §§200 and 210, the Air Quality Division (AQD) of the Department of Energy and Environment (DOEE), located at 1200 First Street NE, 5th Floor, Washington, DC, intends to issue a source category permit to operate certain natural gas-fired emergency engines that are exempt from the federal New Source Performance Standard (NSPS) for spark ignition internal combustion engines (40 CFR 60, Subpart JJJJ) but subject to the National Emission Standards for Hazardous Air Pollutants (NESHAP) for Stationary Reciprocating Internal Combustion Engines (RICE) in the District of Columbia. This source category permit will be designated Permit No. 7116-SC.

To ensure that no engine covered by NSPS Subpart JJJJ is covered by this permit, the applicability criteria for coverage by this source category permit certain exclusions related to the engine maximum power and manufacture date, engine manufacturer’s participation in voluntary manufacturer certification program, and the date of manufacture of such certified engine, or the order date, manufacture date and maximum power of the engine.

Additionally, any engine covered under this source category must meet certain other conditions stated in the source category permit.

Applicants who apply for coverage under a source category permit must document that their equipment meets the applicability criteria specified in the permit prior to approval of coverage and authorization to operate the unit under the authority of the source category permit.

The proposed emission limits to be included in the permit are as follows:

a.   Visible emissions shall not be emitted into the outdoor atmosphere from the engine, except that discharges not exceeding forty percent (40%) opacity (unaveraged) shall be permitted for two (2) minutes in any sixty (60) minute period and for an aggregate of twelve (12) minutes in any twenty-four hour (24 hr.) period during start-up, cleaning, adjustment of combustion controls, or malfunction of the equipment [20 DCMR 606.1].

b.   An emission into the atmosphere of odorous or other air pollutants from any source in any quantity and of any characteristic, and duration which is, or is likely to be injurious to the public health or welfare, or which interferes with the reasonable enjoyment of life or property is prohibited. [20 DCMR 903.1]

Emissions Estimate:

Emissions will vary widely, depending upon the size and age of the equipment to be covered.  As such there is no set maximum emissions level except that no unit will be approved under this permit that has a potential to emit greater than 25 tons per year of oxides of nitrogen, the trigger threshold for further regulatory requirements under 20 DCMR §204 (non-attainment New Source Review).  However, based on past permitting activity implemented by AQD, very few applicants seek to operate natural gas emergency engines in the District of Columbia exceeding 2,000 horsepower (hp) in mechanical output.  Based on a limitation in the permit of 500 hours per year of total operations, conservative emission factors for spark ignition engines, and a 2,000 hp engine size, the following represents an estimate of the maximum emissions expected from any emergency engine covered by this source category permit:


Estimated Maximum Annual Emissions (tons/yr)

Total Particulate Matter (PM Total)


Carbon Monoxide (CO)


Oxides of Nitrogen (NOx)*


Volatile Organic Compounds (VOC)


Sulfur Dioxide (SO2)


*Note that there is an applicability limit placed on the permit that no unit having the potential to emit more than 25 tons/year of NOx will be covered by this source category permit.

The draft permit and supporting documentation are available for public inspection at AQD and copies may be made available between the hours of 8:15 A.M. and 4:45 P.M. Monday through Friday.  Interested parties wishing to view these documents should provide their names, addresses, telephone numbers and affiliation, if any, to Stephen S. Ours at (202) 535-1747.

Interested persons may submit written comments or may request a hearing on this subject within 30 days of publication of this notice.  The written comments must also include the person’s name, telephone number, affiliation, if any, mailing address and a statement outlining the air quality issues in dispute and any facts underscoring those air quality issues.  All relevant comments will be considered in issuing the final permit.

Comments on the proposed permit and any request for a public hearing should be addressed to:

Stephen S. Ours   
Chief, Permitting Branch - Air Quality Division

Department of Energy and Environment
1200 First Street NE, 5th Floor
Washington, DC 20002

[email protected]

No comments or hearing requests submitted after September 19, 2016 will be accepted.

For more information, please contact Stephen S. Ours at (202) 535-1747.