July 26, 2020
Requires Best Available Retrofit Control Technology on engines above 50 bhp. Requirements took effect July 8, 2020.
On July 8, 2020, the San Diego Air Pollution Control Board (SDAPCD) adopted a rule to control oxides of nitrogen (NOx) emissions from all stationary reciprocating engines with a brake horsepower (bhp) rating of 50 or more, including existing 
engines according to a July 24, 2020 Trinity Consultants report. Compliance with the rule may require owners of some existing stationary engines to retrofit emission controls, especially non-emergency engines manufactured before about 2007 or emergency engines put into service after 2000 but manufactured before about 2007.
The new Rule 69.4.1 – Stationary Reciprocating Internal Combustion Engines-Best Available Retrofit Control Technology – replaces Rule 69.4 but carries over some of its provisions. It will require nearly all existing and new stationary engines with a rating of 50 bhp or greater to comply with new emission limits. Notably, most emergency and low-usage engines are no longer exempt from emission limits in the new rule.
The level of the emission limits and percentage reduction requirements will vary depending on whether the unit is existing or new, the type of fuel, and if the operation is emergency or non-emergency.
Additionally, existing stationary engines can implement add-on control technology that achieves designated percentage emission reductions instead of meeting the emissions limits. The rule also includes emission limits for VOC and CO, but these are primarily intended to ensure that engines are not adjusted to achieve NOx compliance in a manner that causes increases in other pollutants to abnormal levels.
Additionally, non-emergency gaseous fueled engines must have a trained operator use a portable analyzer to take NOX and CO emission readings to verify compliance with the emission standards of this rule during every calendar quarter in which a source test is not performed. The “trained operator” must have completed a South Coast Air Quality Management District (SCAQMD)-approved training program and hold the corresponding SCAQMD certification.
Quarterly checks that indicate an exceedance of the rule’s limits must be corrected within 20 days to avoid being considered a violation. Non-emergency gaseous-fueled engines rated 1,000 bhp or above and permitted to operate more than 2,000 hours per calendar year will be required to install and operate continuous emissions monitoring systems (CEMS) and conduct annual emission tests.
All engines subject to the rule emission limits must maintain documentation demonstrating that engine maintenance is being performed at least annually and maintain operating records specified by the rule, including run records from a non-resettable run hour meter or totalizing fuel flow meter. Most engines subject to the emission limits that were not manufacturer-certified to EPA or CARB at the time of manufacture with emission levels that meet these emission limits are required to have an initial emission test and a follow-up test at least every two permit years.
Except for the quarterly portable analyzer check provisions, the new rule requirements have no phase-in period; the requirements took effect on July 8, 2020. As such, facilities with a stationary engine in San Diego County should immediately evaluate the status of their engine(s) under the new rule and take action to ensure there is no gap in compliance.
What this means to you
The San Diego Air Pollution Control Board (SDAPCD) adopted a rule to control oxides of nitrogen (NOx) emissions from all stationary reciprocating engines (including existing engines) with a brake horsepower (bhp) rating of 50 or more. The rule requires using best available retrofit control technology and is effective July 8, 2020.
MIRATECH can help
Contact MIRATECH for stationary engine NOx, CO and VOC emission control solutions within the San Diego Air Pollution Control District.