Monitoring overload?

The Clean Air Act Amendments (CAAA) of 1990 provided the authority for the U.S. Environmental Protection Agency (EPA) to establish an operating permits program and requirements for "enhanced monitoring" of compliance. In 1992, EPA promulgated regulations that established requirements, including monitoring requirements, for operating permits mandated under Title V of the Clean Air Act. A rule establishing requirements for compliance assurance monitoring (CAM) was promulgated in 1997. To augment these rules, EPA continues to publish reference materials to provide general technical information and practical examples for complying with Title V monitoring requirements.

The primary focus of these materials has been to provide examples of monitoring that meet Title V periodic monitoring and CAM requirements. EPA has relied heavily on state and local permitting authorities and industry to provide the information and data for these examples. As a result, technical reference materials and other related efforts are currently in various stages of development at EPA.


A Title V operating permit provides documentation for facility owners, the permitting authority and the public of the air pollution regulations that apply to each emission source at a facility. Prior to Title V, a source's obligations under the Clean Air Act (including emissions limits, monitoring, recordkeeping and reporting requirements) were, in many cases, scattered among numerous provisions of the state implementation plan or federal regulations. Because the Title V permit will clarify in a single document, which requirements apply to a source, the operating permits program will improve compliance with existing regulatory requirements and ensure that the required emission reductions occur in practice and are maintained. The operating permits program is codified 40 Code of Federal Regulations (CFR) 70 and 71. Parts 70 and 71 require that facilities with Title V permits conduct "periodic monitoring" (PMon) to provide a reasonable assurance of compliance with each applicable requirem ent in the operating permit.

On April 14, 2000, the United States Court of Appeals for the District of Columbia Circuit set aside the EPA September 1998 memorandum titled Periodic Monitoring Guidance for Title V Operating Permits Program. The court indicated that state or local permitting authorities and EPA may not use that guidance or Section 70.6(a)(3)(1)(B) of Part 70, the operating permits program, to require a source owner to conduct monitoring more frequently than required in the underlying standard unless the standard requires no periodic testing, specifies no frequency or requires only a one-time test.

The CAAA (Title VII) of 1990 also authorized EPA to develop regulations requiring facilities to monitor the performance of their emission control equipment. EPA established air pollution control device monitoring requirements in the CAM rule (40 CFR 64). The CAM rule applies on a pollutant-specific basis to air pollution sources that are located at a facility required to have a Title V permit; use add-on (active) control devices to control emissions; and are major emission sources (i.e., have the potential to emit PTE uncontrolled emissions greater than the amount which defines a source as a major source under the CAAA). The CAM rule states that compliance assurance monitoring conducted by a source satisfies the periodic monitoring requirements of the Title V operating permits program. Essentially, the CAM rule applies to a subset of the sources required to conduct periodic monitoring under the Title V operating permits program.

Neither the Part 70 Title V operating permit program nor the CAM rules establish specific monitoring approaches that must be used for each type of emission source or control device to provide a reasonable assurance of compliance. Rather, they establish general guidelines and minimum requirements for owners and operators of regulated facilities to follow in selecting an appropriate monitoring approach for proposal to the permitting authority. Ultimately, the permitting authority must approve the selected monitoring approach as a part of the Title V operating permit.

EPA has therefore embarked on a program to provide additional technical information to assist all stakeholders (industry, state and local permitting authorities and the public) in establishing appropriate monitoring for permitted facilities. A primary objective has been to provide real-world examples of monitoring approaches that are approved and are in use, with the caveat that the examples provided are not the only valid approaches for those source types.

Technical reference documents

EPA has prepared two separate technical reference documents, one for CAM and one for PMon, to provide general technical information and practical examples of monitoring approaches. In many cases, the document provides more than one monitoring approach for the same type of source. Both of these documents are living documents; that is, EPA intends to update and revise the documents as new monitoring information becomes available.

CAM technical guidance

The initial version of Technical Guidance Document: Compliance Assurance Monitoring was completed in August 1998. It includes an overview of CAM; detailed information on the purpose and elements of the monitoring approach submittal required by the rule; brief illustrations of monitoring approaches for CAM; technical reference material for monitoring equipment and instruments and detailed example monitoring approach submittals.

Because CAM applies only to sources that use active control devices, all of the monitoring examples in this document are for various sources with different types of add-on control devices (e.g., fabric filters, wet scrubbers, etc.). Although the document briefly addresses monitoring approaches based on the use of continuous emission monitoring systems (CEMS), continuous opacity monitoring systems (COMS) and predictive emission monitoring systems (PEMS), the document focuses on how one goes about establishing a CAM approach based upon monitoring of key control device operating parameters (parametric monitoring). Currently, the document includes 12 detailed example monitoring submittals for seven control device types (fabric filters, wet scrubbers for particulate matter, wet scrubbers for volatile organic compounds, wet electrostatic precipitators, carbon adsorbers, condensers and thermal oxidizers). Table 1 presents a summary of two of the CAM submittal examples included in the docum ent.

Table 1. Examples of compliance assurance monitoring approaches
Example I Example 2
Source Process tank Ceramic fiber blanket manufacture
Pollutant Volatile organic compounds Particulate matter
Control device Packed bed scrubber Fabric filter
Monitoring approach Monitoring water flow using orifice meter Bag leak detector
Indicator(s) Water flow rate Triboelectric signal
Frequency and averaging period Measured continuously, recorded each minute, one hour average Measured continuously
Quality assurance Weekly zero, quarterly upscale check Monthly inspection of probe, calibration of electronics

Periodic monitoring technical guidance

A draft version of the Periodic Monitoring Technical Reference Document was published for public comment in April 1999 on EPA's Technology Transfer Network Web site. This document includes the principles of periodic monitoring; the minimum requirements for periodic monitoring; an evaluation process which may be used to determine appropriate periodic monitoring; a summary of monitoring approaches for various types of applicable requirements; a summary of the basic types of monitoring approaches and information that should be included in the operating permit for the monitoring and example periodic monitoring approaches for various source types.

Because the CAM technical guidance document focuses on monitoring approaches for sources with add-on control devices, the periodic monitoring technical reference document focuses on monitoring for sources that do not use add-on control devices to comply with their applicable requirements. The types of monitoring approaches discussed include CEMS, COMS, PEMS, parametric monitoring (i.e., monitoring process operating parameters such as temperature and feed rate), monitoring raw material pollutant content and performing a mass balance, recordkeeping for work practices, inspection and maintenance recordkeeping and periodic emissions testing. Currently, a total of 16 examples of periodic monitoring are included in the document for various types of emission sources, including combustion sources, fugitive particulate matter (PM) and VOC sources, coating operations and other PM and VOC sources. Table 2 presents a summary of two of the periodic monitoring examples included in the document.

Table 2. Examples of periodic monitoring approaches
Example 1 Example 2
Source Surface coating operation Ore crusher
Applicable requirement Limit VOC content of each coating to 2.9 lb./gal. Opacity never to exceed 15 percent
Monitoring approach Measurement of coating VOC content using Method 24 Visible emissions (VE) observation by Method 22; opacity observation if any visible emissions are observed
Indicator range VOC content less than 2.9 lb./gal, minus water and exempt compounds VE, no VE
Opacity: less than 15 percent
Frequency and averaging period Before initial use of each new coating Daily observation, no averaging period
Quality assurance Per Method 24 VE: Per Method 22
Opacity: Per Method 203C

Future plans

As previously mentioned, EPA considers both of these living documents, to be updated as additional information, particularly new monitoring examples, become available. EPA has been actively pursuing new examples for the CAM and PMon technical documents and currently has several examples in various stages of completion. Tables 3 and 4 list some of the CAM and PMon examples, respectively, that are currently in progress. EPA continues to solicit additional examples from industry and permitting authorities. Some of the source/pollutant/control technology/monitoring combinations for which EPA has a particular interest in obtaining monitoring examples are presented in Table 5. If you would like to contribute, please contact Mr. Peter Westlin at (919) 541-1058 or

Table 3. CAM examples in progress
Control device Monitoring approach
Catalytic oxidizer Parametric monitoring, catalyst testing
Carbon adsorber Breakthrough detector
Fabric filter PM CEMS
Electrified filter bed Parametric monitoring
Electrostatic precipitator (ESP) COMS and ESP performance model
Packed bed scrubber Parametric monitoring
Capture efficiency Pressure differential
Wet electrostatic precipitator Parametric monitoring
Venturi scrubber Parametric monitoring
Multiclone Parametric monitoring
Bypass control Parametric monitoring

Table 4. Periodic monitoring examples in progress
Source type/pollutant Monitoring approach
Boiler, nitrogen oxides PEMS
Diesel engine, PM/opacity Visible emissions, opacity
Internal combustion engine, nitrogen oxides Periodic testing
Internal combustion engine, nitrogen oxides PEMS
Oven, VOC Parametric monitoring
Cold cleaner, VOC Work practice documentation

Table 5. CAM and periodic monitoring examples wanted
Source type/control device Monitoring approach
Carbon adsorber Parametric monitoring
Fabric filter with dry injection Parametric monitoring
ESP Parametric monitoring
Nitrogen oxide controls, sulfur dioxide controls Other than CEMS
Capture efficiency for room enclosure Parametric monitoring/inspections
Regenerative thermal/catalytic oxidizer Parametric monitoring
Combustion sources Parametric monitoring combined with periodic testing using portable analyzer

In addition to updating the CAM and PMon technical documents, EPA also intends to publish a citizen's guide to Title V monitoring. This guide will be structured toward addressing citizen concerns about how facilities in their communities are maintaining good pollution control practices and assuring compliance with applicable requirements. EPA also plans to promulgate performance specifications and quality assurance (QA) procedures for continuous parameter monitoring systems (CPMS), including temperature, pressure, flow and pH monitoring systems used to comply with requirements such as maximum achievable control technology (MACT) and new source performance standards (NSPS), as well as CAM and PMon. For more information on these two efforts, please contact Mr. Barrett Parker at (919) 541-5635 or at

The purpose of this paper is to provide technical inforamtion only on what resources are available to source owners and operators and to permitting authorities in addressing monitoring questions that arise relative to implementing part 64, the compliance assurance monitoring (CAM) rule, or as defined in part 70 and clarified in the court's decision. Any examples described in this paper are illustrative and are not intended to establish minimum acceptable monitoring requirements ofr the operating permits program.


EPA's Emissions Measurement Center (EMC) Web site (including downloadable technical reference documents) —

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This article appeared in Environmental Protection magazine, June 2000, Vol. 11, No. 6, p. 40.

This article originally appeared in the 06/01/2000 issue of Environmental Protection.

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