South Coast Air Quality Management District (SCAQMD) is proposing Rule 1159.1 to control NOx emissions from nitric acid tanks.
Rule 1159.1 aims to reduce NOx emissions by limiting emissions of nitric acid tanks both with and without air pollution control device (APCD). This rule is going into effect starting January 1, 2025.
Cleaning tanks, rinse tanks, and storage tanks are exempt from compliance requirements.
Applicability
Any owners or operators of facilities with one or more nitric acid units must comply with Rule 1159.1. A nitric acid unit (NAU) is defined as a container containing nitric acid, in which the nitric acid reacts with a metal or decomposes at a temperature greater than 1,700° F.
Compliance Requirements
NAUs Vented to APCD
Conduct source testing to meet requirements:
- R1: ≤0.30 lb-NOx/hour/APCD, and ≤0.90 lb-NOx/hour across all APCDs; or
- R2: NOx control efficiency of 99%.
- R3: Submit SCAQMD Permit Application for APCD(s).
NAUs NOT Vented to APCD
- R4: Conduct source testing to ensure ≤0.60 lb-NOx/hour across all NAUs; or
- R5: Record Additions to NAUs. Thresholds are for any 2 calendar years of the most recent 5 calendar year period:
- 550 gallons of nitric acid calculated at 68WT% per calendar year per NAU; and
- 1,650 gallons of nitric acid calculated at 68WT% per calendar year for all NAUs.
- Facilities exceeding the thresholds inR5 will be required to install control devices or submit further source tests according to R1, R2, or R4.
- These requirements (R1-R5) will be implemented according to the implementation schedule below:
Table 1. Implementation Schedule
| Date Initial Permit to Operate Issued for NAU | Rule Requirement | Compliance Date |
| On or before [Date of Adoption] | R3, R4, R5 | January 1, 2026 |
| R1, R2 | January 1, 2028 |
| After [Date of Adoption] | R1, R2 | Beginning 120 days after initial operation of APCD |
| R4 | Beginning 120 days after initial operation of NAU |
Labeling Requirements
Beginning July 1, 2025, label:
- NAUs:
- Tank number
- SCAQMD application / permit number;
- Cleaning tanks:
- SCAQMD tank number
- “Rule 1159.1 Cleaning Tank”
- SCAQMD permit number.
Inspection & Maintenance Requirements
- At least once every quarter conduct visual inspections for leaks and malfunctions on the APCD
- Maintain and operate the APCD according to the manufacturer’s specifications and recommendations.
Monitoring, Recordkeeping, & Reporting Requirements
The volume of nitric acid added to tanks must be recorded on a regular basis (calculated to 68 WT%, for each addition, on a monthly and also yearly basis according to Appendix A). Control devices will be required to keep records of flowrate, pH, and pressure drop on a weekly basis.
Maintain all records for at least five years.
Additional Information
More detailed information on SCAQMD Rule 1159.1 can be found in the Preliminary Draft Language.
If you have any questions regarding the regulation, need assistance with calculations (pursuant to Appendix A) for NAUs without APCDs, or maintaining compliance for your facility, please email Marcus Firstman or Trinity’s Irvine office.
