James A. Jahnke - Continuous Emission Monitoring

Part 51 Appendix P – Minimum Requirements for Existing Sources . In Appendix P of Part 51, the U.S. EPA established minimum CEM requirements for existing sources (U.S. EPA 2020a). The rules, published in the 1970s, required state CEM requirements to be written by 1976 for only four source categories: fossil‐fuel‐fired steam generators, sulfuric acid plants, nitric acid plants, and petroleum refineries. Even so, these particular minimum requirements only applied to larger sources and allowed many exemptions, such as not requiring SO 2monitoring unless SO 2control systems are installed. The “existing sources” referenced in Part 51 were those built before 1971, many of which are no longer operating by having become subject to reclassification as a “new source” after modification, or are otherwise subject to acid rain, air toxics, and other rules written after promulgation of the 1990 Clean Air Act Amendments. Once in the Code of Federal regulations, rules, test methods, and procedures tend not to go away. They layer upon themselves; so, when reading them, attention must be paid to applicability and other conditions of the requirements.

TABLE 2‐2 State CEM Program Options

Part 52 – Approval and Promulgation of implementation Plans Part 52.21 – Prevention of Significant Deterioration (PSD) For any source or a major modification to an existing source, located in an attainment area, where ambient air standards are met, a PSD permit must be granted. Once an area is in attainment, it is possible that the construction of a new source or modification of an existing source could lead to “significant” emissions that bring the area into nonattainment. To avoid this possibility a permit must be obtained by the source prior to the construction or modification. It must be shown whether a significant increase of emissions will occur, through a technical analysis and an air quality modeling, as specified in Part 52.21. One of the requirements of Part 52.21 is that the after construction or modification, the source must monitor mass emissions in tons per year of any pollutant designated under the New Source Review program for at least five years.

Part 62 gives requirements for existing sources that are not regulated by a state or tribal plan. The Subparts of Part 62 give Federal plans that can be delegated to the states for implementation by existing stationary sources. The applicable plan must be included in the Title V Permit for the affected source. Part 62 addresses a variety of incineration facilities listed in Table 2‐3. For a number of the sources, options are offered for using CEM systems instead of periodic performance testing.

Congress established the Title V Operating Permit Program under the 1990 Clean Air Act Amendments. Under the program, major sources are required to obtain operating permits, operate in compliance with the permit, and certify annually that they are in compliance with the permit requirements. Most permits are issued by state and local agencies following the requirements of 40 CFR Part 70. Federal permits can be issued following 40 CFR Part 71.

TABLE 2‐3 Summary of 40 CFR 62 Monitoring Requirements for Existing Units Not Covered by an Approved and Effective State or Tribal Plan

aModification began before this date

bUnits > 250 tpd capacity

States issue operating permits for both existing and new stationary sources.

An operating permit may include conditions that require the installation of CEM systems. States may prepare rules for existing sources that are more stringent than those promulgated by the federal agency (Kerstetter 1985). As a result, the stringency of state CEM rules may extend beyond those established for similar sources regulated under NSPS. Monitoring of gases such as HCl or volatile organic compounds may be required, or process cutoffs for excess emissions or real‐time telemetry may be required in the permit. Sources often agree to very stringent CEM requirements to expedite approval of the operating permit.

Most states have received delegation by the U.S. EPA to regulate the emission sources affected by the following federal rules:

Part 60 New Source Performance Standards

Part 64 Compliance Assurance Monitoring.

Parts 266 and 503 Hazardous and Municipal Waste Incineration

In implementing these programs, states have developed regulations to assure that affected sources have installed required CEM systems, to see that they are properly certified, and to receive and process excess emission reports and compliance data as required by the applicable rule.

The Cross‐State Air Pollution Rule, of 40 CFR 96, evolved from the Clean Air Interstate Rule (CAIR) and the NO xBudget Program (NBP). After the promulgation of Part 75 and the implementation of the acid rain program, significant progress was made in reducing SO 2and NO xemissions. However, even with 50% reductions in SO 2and NO xemissions, critical load was not being reached. “Critical load” is the level of emissions below which harmful effects to the environment do not occur. Studies indicated that reductions on the order of 75% on top of the previous 50% reductions would be necessary for SO 2and NO xto meet ambient air standards for ozone and particulate matter, as well as reaching critical load requirements for acid rain. In the East, it was felt that part of the problem was due to the interstate transport of pollutants from the western to eastern parts of the United States. Thus, began the saga of rulemaking that extended from the NO xBudget Trading Program, to the Clean air Interstate Rule, and to the Cross‐State Air Pollution Rule, which is in effect today.