In December 2022, the Colorado Department of Public Health and Environment (CDPHE) published guidelines for the design, operation and maintenance of Automatic Pressure Management and Pilot Light Systems (APMPLS) at well production facilities in Colorado. These guidelines satisfy the requirements for well production facilities’ alternative leak detection and repair inspection frequencies in Regulation No. 7, Part D.II.E.4.f. Regulation 7 controls VOC emissions.
The APMPLS guidelines require procedures that include the following:
- Continuously monitor storage tank pressure and control liquid flow and vapor flow to the tanks based on tank pressures.
- Continuously monitor pilot light operation on emission control combustion devices.
- Detect when a thief hatch may be open.
- Shut-in flow to storage tanks if pressure levels indicate venting.
- Shut-in flow to storage tanks if there is a pilot light outage of more than five (5) minutes.
- Conduct a site investigation for potential venting and pilot light outages.
- Recordkeeping and reporting consistent with the guidelines.
- Submit your procedures to Division review and evaluation.
Three distinct systems must be monitored and managed by an APMPLS include:
- Automatic Tank Pressure Management
- Pilot Light Monitoring
- Thief Hatch Monitoring
Automatic Tank Pressure Management
Automatic tank pressure management systems continuously monitor pressure within storage tanks and uses a valve to control liquid flow and vapor flow from the separators to the tanks to prevent over pressurization and venting. It also shuts-in flow upon over pressurization.
An automatic tank pressure management system acts at the following three (3) pressure levels within the storage tanks:
- Leak Point
- Control Point
- Open Point
The Leak Point is determined using onsite testing with an infrared camera and the other pressure levels are selected based the facility’s operating conditions.
Pressure Sensor Usage
Facilities with multiple storage tanks that are vapor-connected require pressure monitoring on only one of the storage tanks. The APMPLS logic must restrict and/or shut-in flow to all vapor-connected tanks, and not just the tank with the pressure monitor. For multiple storage tanks not vapor-connected, separate pressure monitors are required on each vapor space.
Leak Point
The Leak Point is the lowest pressure value (in oz/in2) at which a pressure relief device or thief hatch begins to vent due to over pressurization in a specific tank battery. The Leak Point must be determined on a tank battery-specific basis, using an infrared camera.
A pressure reading at the Leak Point indicates that the storage tanks are venting. The APMPLS must shut off flow to the storage tanks and the operator must conduct a site investigation. Flow to the storage tanks must remain shut off until the root cause of the pressure reaching the Leak Point is addressed.
If the operator makes changes to the APMPLS system, they must re-determine the Leak Point within 30 days or before returning the storage tanks to normal operations, whichever is later. These changes include replacing a thief hatch or pressure relief valve with a different make and model or lower nameplate relief pressure, or changing a pressure monitor on the APMPLS system.
The owner or operator must keep a record of every time the Leak Point is reached.
Control Point
The Control Point is the tank pressure at which the valves close to stop or restrict flow from the separators to the storage tanks. It is set below the Leak Point and may be reached frequently without indicating a problem. When tank pressures drop below the Open Point, flow from the separators to the tanks will automatically resume.
The Control Point is chosen by the operator to allow production without reaching the Leak Point tank pressure. It should be set lower than the Leak Point to prevent the Leak Point from being reached when the valves are closed, and the tank continues to pressurize.
There is no requirement for the operator to keep a record when the Control Point is reached.
Open Point
The Open Point is the tank pressure at which the valves that were closed at the Control Point are re-opened to allow flow from the separators to the tanks to resume. It is selected by the operator and should be set lower than the Control Point to allow the vapor control system and control equipment to effectively reduce tank pressures.
There is no requirement for the operator to keep a record when the Open Point is reached.
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Pilot Light Monitoring
The APMPLS system must include continuous monitoring capable of continuous (at least once every five (5) minutes) monitoring for the presence of a pilot light.
Many enclosed combustion devices (ECDs) use an auto-igniter to relight the pilot. If the auto-igniter fails to relight the pilot light, and the pilot light is out for five (5) or more minutes, then the APMPLS system must shut-in flow to the storage tanks.
If the pilot light status is checked every five minutes, shut-in must occur after two consecutive readings show that the pilot is out. If the pilot light status is checked more frequently than every five minutes, shut-in must be triggered within five minutes of the first reading that the pilot is out.
If there are multiple ECDs at the facility controlling emissions, the pilot lights on each ECD must be monitored. For burner management systems used for a group of ECDs, the operator’s written materials should detail how a pilot light outage at an ECD is handled.
After flows to the storage tanks are shut-in by the APMPLS due to a pilot light outage, flow can be resumed after:
- Pilot light is re-lit;
- Completion of corrective action and responses
- Recordkeeping is completed
The facility operation must submit written procedure to the CDPHE for:
- How the system detects a pilot light outage, including the technology used and measurement frequency
- How the system shuts off flow to the storage tanks if the pilot light is not relit immediately
- Actions taken during a shut-in event caused by a pilot light outage
- How other facility controls, such as burner management systems, affect pilot light monitoring and responses
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Thief Hatch Monitoring
The APMPLS must continuously detect an open or unlatched thief hatch by detecting a drop in storage tank pressure levels. If the thief hatch is open for any reason other than tank maintenance, gauging, or the safety of personnel and equipment, the APMPLS must shut off flow to the storage tanks and the operator must conduct a site investigation.
The monitoring of thief hatch status can be done through continuous pressure data observation with automated logic. A sudden drop in storage tank pressure followed by sustained near- or at atmospheric pressure for an extended period of time indicates an open thief hatch. The owner or operator should include in their written materials the logic that accounts for these parameters and also accommodates and avoids shut-off during instances when the thief hatch is opened for maintenance, gauging, or the safety of personnel and equipment.
Continuous pressure data monitoring with automated logic can be used. A sudden drop in storage tank pressure followed by sustained near- or at atmospheric pressure for an extended period of time indicates an open thief hatch.
For storage tank shut-in due to an open thief hatch, flow can be resumed after the site investigation is completed and the thief hatch is closed and the company completes corrective actions.
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Operating and Maintenance after Startup
The operator must implement plans for maintenance activities on the storage tank and automatic tank pressure management system, including verification/recalibration of pressure monitors and testing of valve actuation. Maintenance activities must be completed at least semi-annually. The plan should discuss how the operator will manage malfunctions, emergency situations, and facility maintenance shutdowns at locations using APMPLS.
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Submission of APMPLS
The facility operator must notify the Air Pollution Control Division of the intent to follow these guidelines, using the online APMPLS Google Form.
Recordkeeping
Specific recordkeeping required for each APMPLS.
Remote monitoring of APMPLS, by SCADA or equivalent, is required. This must include automatic alarm notification of all shut-in events due to venting (over pressurization and/or open thief hatch) or pilot light outage. Alarms and notifications are not required for Control Point or Open Point events.
For each facility with an APMPLS, records must be maintained and made available to the Air Pollution Control Division upon request.
All required records must be maintained for a minimum of five (5) years.
Cimarron Solutions:   ARC™ Burner Management System (BMS)
Sytelink Cellular Gateway and Dashboard System for Environmental Control Equipment Performance Monitoring
Additional Resources
For questions regarding the guidelines, contact the Air Pollution Control Division at:
Main phone: (303) 692-3150
cdphe.commentsapcd@state.co.us
Other Cimarron Solutions:
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