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Approved Instrument Monitoring Method (AIMM) for oil & gas

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Overview

An Approved Instrument Monitoring Method (AIMM) must be used to inspect components, storage tanks and natural gas-driven pneumatic controllers at well production facilities, natural gas compressor stations, and natural gas processing plants (storage tanks only) under the Leak Detection and Repair (LDAR), Storage Tank Emission Management (STEM) and Natural Gas-Actuated Pneumatic Controller requirements of Air Quality Control Commission (AQCC) Regulation 7.

AQCC Regulation 7 defines AIMM as an infrared (IR) camera, EPA Method 21, or other instrument based monitoring method or program approved in accordance with the requirements of Regulation 7, Part B, Section I.L.8 (“Alternative AIMM”).

Although Section I.L.8 is specific to the Ozone Control Area or Nonattainment Area (NAA), the Air Pollution Control Division will use the requirements in Section I.L.8. to evaluate all Alternative AIMM regardless of where the AIMM may be used in Colorado. However, an Alternative AIMM that requests to be used exclusively outside the NAA will not be subject to the public notice and EPA review and approval provisions of Section I.L.8.a.(iv).

Infrared camera

Regulation 7, Part B, Sections I.B.17. and II.A.12. define an IR camera as “an optical gas imaging instrument designed for and capable of detecting hydrocarbons.”

The following list provides examples of handheld, and tripod-mounted IR cameras that meet the above noted definition:

  • FLIR models GF300, GF320, Gx320, GFx320, G620, GF620, Gx620
  • Opgal EyeCGas camera
  • Infrared Cameras Inc. (ICI) Gas DetectIR VOC
  • Konica Minolta Gas Camera System, Models: GMP01, GMP02 (without quantification)
  • Ventus OGI-Camera MWIR Core installed in any unmanned aerial system or custom-built handheld camera

Note: IR cameras that are optimized for the detection of methane but have reduced detection capabilities for total hydrocarbons including volatile organic compounds, such as uncooled long-wave infrared (LWIR) cameras, do not meet the definition of an IR camera under Regulation 7 and are required to obtain an Alternative AIMM approval prior to use for meeting Regulation 7 monitoring requirements. This is required because Regulation 7 applies to total hydrocarbons (methane and volatile organic compounds) for oil and gas. The Alternative AIMM provision in Regulation 7 allows for approval of monitoring technologies that are optimized or specific to methane if the Alternative AIMM requirements are met.

Additionally, an IR camera that offers or utilizes quantification capabilities that will be used for the determination of an emissions leak requiring repair will also need to obtain Alternative AIMM approval since Regulation 7 specifies that any emissions associated with a leak detected by an IR camera require leak repair. An Alternative AIMM approval, however, allows for the leak identification requiring repair to be established as set forth in the approval. 

A non-handheld IR camera used in a mobile monitoring platform or deployment method (vehicle-mounted or aerial) will be required to develop and implement a monitoring plan in order to be used for Regulation No. 7 monitoring requirements. For details regarding the monitoring plan view the Alternative AIMM Guidance & Procedures document.

EPA Method 21

EPA Method 21 states the instrument detector type is not specified, but it must meet the specifications and performance criteria in Section 6.0 of the method. Example instrument detector types for meeting EPA Method 21 criteria include flame ionization detectors (FID) and photo ionization detectors (PID).

Alternative AIMM

  • Alternative AIMM Application Form.
  • Alternative AIMM Guidance &, Procedures document, which provides information on the Alternative AIMM application process, as well as monitoring plan requirements for non-handheld IR cameras.
  • Submit completed Alternative AIMM application and supporting documentation to cdphe_aimm@state.co.us.
  • Alternative AIMM approved for use to meet Regulation 7 requirements will be issued an approval letter outlining the conditions of approval. An approved Alternative AIMM may be used by anyone to meet Regulation 7 requirements provided the approval conditions are met. Please see below for currently issued Alternative AIMM approval letters.
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Alternative AIMM public notices

According to the Air Quality Control Commission (AQCC) Regulation No. 7, Part B, Section I.L.8, an Alternative Approved Instrument Monitoring Method (AIMM) that the Air Pollution Control Division has approved for use in the ozone nonattainment area is required to be posted to public notice and approved by the EPA.

During a public notice period, the division posts the submitted Alternative AIMM application, draft approval letter, and application analysis documents on this webpage and requests written comments from the public. Any confidential business information (CBI) included in the Alternative AIMM application must be marked as such to be processed by the division as CBI, according to the Colorado Department of Public Health & Environment’s CBI policy. An Alternative AIMM application with CBI will have a redacted version of the application (minus CBI) posted for public notice.

If you would like to submit a public comment for an Alternative AIMM application and draft approval, please review the Public Participation Guidance first. This information is specific to public comments for permits and also applies to public comments for Alternative AIMM applications.

Current public notices

Closed public notices

Alternative AIMM approval letters

Alternative AIMM and Title V operating permits

If an approved Alternative AIMM will be used at a facility subject to Title V Operating Permit requirements, the Alternative AIMM must first be documented within the Title V Operating Permit. Please submit a complete Title V Operating Permit modification application or revise a previously submitted Title V Operating Permit application requesting use of the approved Alternative AIMM at a subject facility before implementation of the Alternative AIMM at the facility.

Contact us

Questions? Email cdphe_aimm@state.co.us.

If you have any questions, general comments, or would like to send us additional information, contact us at cdphe.commentsapcd@state.co.us .

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