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Proposed Air Quality Permit 7043-SC – Permit to Construct and Operate Gas-Fired Emergency Engines

Friday, August 14, 2015


Proposed Air Quality Permit 7043-SC – Source Category Permit to Construct and Operate Stationary Natural Gas-Fired Emergency Engines Subject to NSPS Subpart JJJJ 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 construct and operate certain natural gas-fired emergency engines subject to the federal New Source Performance Standard (NSPS) for spark ignition internal combustion engines (40 CFR 60, Subpart JJJJ) in the District of Columbia. This source category permit will be designated Permit No. 7043-SC.

This source category permit will cover only a subset of stationary natural gas-fired emergency engines that trigger NSPS Subpart JJJJ applicability based on one of the following triggers:

1.   The maximum engine power is less than or equal to 25 horsepower (HP) [19 mechanical kilowatts (kWm)] and it was manufactured on or after July 1, 2008;

2.   The manufacturer participates in the voluntary manufacturer certification program described in 40 CFR 60, Subpart JJJJ and the date of manufacture of the emergency engine is after January 1, 2009; or

3.   The emergency engine was ordered after June 12, 2006, was manufactured on or after January 1, 2009, and has a maximum engine power greater than 25 HP (19 kWm).

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

a.   Emissions the engine shall not exceed those specified in 40 CFR 60.4233 for the appropriate engine type.  Any engine subject to a Family Emission Limit (FEL) shall comply with any such limits as specified on an EPA Certificate of Conformity.  If the engine is certified as a non-emergency engine, the engine shall comply with the standards to which it has been certified. [40 CFR 60.4233 and 20 DCMR 201]

b.   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].

c.   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]

Emission 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 §205 (non-attainment New Source Review).  However, based on past permitting activity implemented by AQD, very few natural gas-fired emergency engines in the District of Columbia exceed 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)


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 written comments or hearing requests postmarked after September 14, 2015 will be accepted.

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