Control of VOC Leaks & Releases from Components at Petroleum Facilities & Chemical Plants
South Coast Air Quality Management District (South Coast AQMD) is proposing to amend Rule 1173. Rule 1173 applies to refineries, chemical plants, lubricating oil and grease re-refiners, marine terminals, oil and gas production fields, natural gas processing plants, and pipeline transfer stations.
The objective of Rule 1173 is to control Volatile Organic Compound (VOC) leaks and releases from components at petroleum facilities and chemical plants. The proposed rule amendments aim to further reduce VOC emissions from components like valves, flanges, and other equipment that might leak VOCs by enhanced leak detection technology, increased frequency of monitoring and lower leak standards.
Additionally, the proposed amendments also aim to establish contingency measures to address VOC emissions in the event of nonattainment with ozone standards to achieve a greater reduction in VOC emissions, contributing to cleaner air and better public health outcomes
The proposed changes in the rule are expected to be effective starting October 1, 2025. The interim standards which reflect existing Rule 1173 standards are effective until the compliance deadline.
Key Elements of Proposed Amended Rule 1173
In addition to the many new definitions added to the rule for better clarity and applicability determination, following key changes to South Coast AQMD’s inspection procedures are crucial:
Violation Standards
As shown in the table below, the liquid and gas/vapor service component violation standard is updated.
| Component Service | Standard (ppm) |
| Existing | Proposed |
| Light Liquid and Gas/Vapor | 50,000 | 10,000 |
| Heavy Liquid | 500 | No Change |
If found in violation of the standards above by SCAQMD personnel, one day after detection facilities must demonstrate the component no longer exceeds these standards and does not release visible vapors. For inaccessible components, notify the Executive Officer electronically by end of operating shift (no more than 12 hours) and fix within 14 calendar days.
Component Leak Standards
The amendment proposes stricter leak standards, meaning that even smaller leaks would need to be addressed. This aims to minimize emissions by ensuring that all significant sources of VOCs are effectively controlled.
| Component Type | Standard (ppm) |
| Existing | Proposed |
| Compressor or Pump (Light Liquid) | 500 | 400 |
| Pressure Relief Device (PRD) | 200 | 200 |
| Pump (Heavy Liquid) | 100 | 100 |
| Valve, Fitting, or Other Device (Diaphragm, Hatch, Sight-glass, Meter) | 500 | 100 |
If found in violation of Component Leak Standards by SCAQMD personnel, 14 days after detection facilities must demonstrate the component complies with these standards. Previously, components found in violation of either Violation or Component Leak Standards had varying periods (between 1-7 days) that were allotted for fixing different components.
Atmospheric Process PRD Requirements
The compliance schedule for the requirement to continuously monitor PRDs has been removed. The threshold of 500 pounds of VOC releases before performing failure analysis has been deleted. Additionally, the mitigation fee has been adjusted for inflation.
Non-Attainment Ozone Contingency Measures
Contingency Measure (CM) is a control strategy to further reduce VOC emissions if the South Coast Air Basin fails to make reasonable further progress (RFP), or to attain the applicable National Ambient Air Quality Standard (NAAQS) for ozone by a specified attainment date. The following CMs are effective 60 days after issuance of each final determination.
| Stage | Component Type | Control Measure |
| Existing | Proposed |
| 1 | Compressors & Pumps (Light Liquid) | 400 ppm | 300 ppm |
| 2 | OGI Inspection Frequency | Once a Month | Every 2 Weeks |
| 3 | Valve, Fitting, or Other Device (Diaphragm, Hatch, Sight-Glass, Meter) | 100 ppm | 50 ppm |
Classification
| Standard | Level | South Coast (SC) | Coachella Valley (CV) | Attainment Date |
| 2015 8-hour Ozone | 70 ppb | Extreme | Severe | August 3, 2038 (SC) | August 3, 2033 (CV) |
| 2008 8-hour Ozone | 75 ppb | Extreme | Severe | July 20, 2032 (SC) | July 20, 2027 (CV) |
| 1997 8-hour Ozone | 80 ppb | Extreme | Severe | June 15, 2024 (both SC & CV) |
| 1997 1-hour Ozone | 120 ppb | Extreme | Attainment | December 31, 2022 (SC) |
Reporting & Recordkeeping
The following are the key changes in the rule:
- Electronic records submission is required.
- Record retention is required for at least five (5) years.
Self-Inspection
Audible, Visual, and Olfactory (AVO) inspections of all accessible pumps, compressors, and PRDs must be conducted at least every 12 hours and weekly for unmanned facilities. Additionally, Optical Gas Imaging (OGI) Inspections must be performed on each component at least once per calendar month. Analyzer Inspections will be required to be conducted quarterly for all accessible components and annually for all inaccessible components. Previously, AVO tests were required to be completed every 8 hours and the rule had no such requirement for unmanned facilities.
Trinity can assist with reporting, calculations, and compliance strategies with both rules. If you have any questions regarding the rule and maintaining compliance for your facility, please email Pragya Sharma or Trinity’s Irvine office.
