Taking it to the max

Section 112 of the 1990 Clean Air Act Amendments (CAAA) mandates the U.S. Environmental Protection Agenc (EPA) to develop maximum achievable control technology (MACT) standards that regulate emissions of hazardous air pollutants (HAPs) from specific industries. These standards usually impact plant sites (contiguous and under common control) within target industries that are classified as major sources of HAPs. A major HAP source is one that produces air emissions of 10 tons per year (tpy) of a single HAP and/or 25 tpy of combined HAPs. Once a MACT standard has been promulgated by EPA, existing sources have three years to achieve compliance. New sources must be in compliance upon startup.

MACT development update

The concept of the MACT standards as industry-specific National Emission Standards for Hazardous Air Pollutants (NESHAP) was first introduced in 1990 as part of the CAAA. Although there was a NESHAP program initiated by the 1977 CAAA, there were only six pollutants for which standards were developed. Those original NESHAPS remain in effect today. The list of target source categories was initially published in the Federal Register in 1992. EPA regularly updates this list as MACT standards are promulgated or source categories are delisted or combined.

In 1990, EPA adopted a staggered schedule for the promulgation of the MACT standards. The source categories were split into four groups known as the two-year, four-year, seven-year, and 10-year "bins." As originally planned, the two-year bin would include at least 40 source categories with a promulgation deadline of 1992. The four-year bin would include 25 percent of the initial list of source categories (including the first 40 categories), to be promulgated by 1994. The seven-year bin would include an additional 25 percent of the source categories, due by 1997. Finally, the 10-year bin would include the remaining 50 percent of the source categories, due by November 2000. All of the two-year and the four-year standards were promulgated on schedule. Although some of the standards scheduled for the seven-year were delayed, EPA is now planning to propose all remaining MACT standards by November 2000.

Some of the important MACT standards that have been promulgated so far address the following industries:

  • Synthetic organic chemicals;
  • Petroleum refineries;
  • Polymers and resins;
  • Pulp and paper;
  • Pharmaceuticals;
  • Pesticides;
  • Aerospace; and
  • Oil and natural gas production.

Some other industries that are in the 10-year bin that should expect a proposed MACT standard shortly include:

  • Miscellaneous organic chemicals;
  • Surface coatings;
  • Cellulose manufacturing;
  • Ethylene processes;
  • Chlorine production;
  • Polyvinyl chloride and copolymers production;
  • Rubber tire production;
  • Plywood and composite wood products; and
  • Combustion equipment.

Common features

All of the promulgated MACT standards have essentially the same basic structure, including:

  • Applicability;
  • Definitions;
  • Standards for equipment covered under the "affected source";
  • Compliance testing and/or design evaluation;
  • Monitoring;
  • Record keeping; and
  • Reporting.

Source regulation

An affected source is regulated for HAP emissions during both normal operations and startup, shutdown and malfunction (SSM) events. Compliance testing is used to determine conformance with the standard during normal operations. The monitoring ranges that are established during compliance testing and/or design evaluation determine ongoing compliance with the MACT standard.

Deviations are usually reported as excursions, or in certain cases, as direct violations of the emission standard. Records are required for applicability determinations, testing and all monitoring data that is utilized to demonstrate compliance during both normal operations and SSM events. Reports pertaining to both normal operations and SSM events must be sent to the appropriate regulatory agency to demonstrate compliance.

Some of the important plans and programs that owners/operators must prepare and implement under the MACT standards are the SSM plan, the site-specific inspection plan for the closed vent system, the operation and maintenance plan for certain control devices and the leak detection and repair (LDAR) program.

An effective strategy for compliance

So what constitutes compliance with MACT standards? What does it mean in terms of tangibles and intangibles? In terms of tangibles, MACT compliance means compliance with the control requirements and subsequently, compliance with the monitoring, record keeping and reporting provisions contained in the standard. The intangible inevitably follows — peace of mind for an affected facility's owners or operators that have implemented the required tangibles.

An affected plant must install control equipment to ensure adequate HAP removal. Complying with control requirements usually involves large capital expenditures, a primary concern for industry. However, an owner/operator msut never assume that if he or she has a device that controls HAP streams, he or she will automatically be in compliance.

Although the one-time installation of adequate controls may involve a large investment, it is the ongoing compliance requirement that is the real challenge. Ongoing compliance assurance is usually the more onerous element of MACT compliance because it is a long-term requirement, with the exact method for ensuring compliance largely undefined. The MACT standards provide an affected facility latitude to set up its own system of ensuring continuous compliance. An adequate system could be a fully automated data management system that records operating parameters and generates the appropriate agency reports, or it could be a mix of automated and manual elements designed to accomplish the same objective. Strategies for effective compliance with MACT standards encompass both of the above elements — the right control technology and an apt and reliable system to demonstrate ongoing compliance.

For the environmental personnel responsible for compliance, there are two important questions that should be addressed when considering compliance strategies. They are when should I really gear up for compliance, and what is the best way to achieve compliance with minimal cost while ensuring peace of mind with respect to agency inspections and enforcement?

With respect to the first question, it is important to understand the requirements as soon as a standard affecting your industry is promulgated. Better still, it may be advisable to become involved with the regulation at the draft stage so that you can influence the final standard if there is a legitimate technical issue that concerns your facility.

The answer to the second question is that the affected facility should perform the following steps to achieve compliance:

  • Conduct an initial site assessment with respect to the promulgated standards;
  • Determine whether the facility requires any additional controls for compliance;
  • Assess and optimize the facility's existing procedures relative to ongoing requirements; and
  • Prepare and implement the requisite plans and programs per the MACT requirements.

These steps are critical, not only to determine the current status of the facility with respect to the impending standards, but also to achieve compliance by the effective date and maintain ongoing compliance with the standards.

All the above steps should be conducted by personnel who have prior experience with successful implementation of MACT standards. This is because there have been substantial transfers of MACT requirements across industries, many based on the provisions of the Hazardous Organic NESHAP (HON). Thus, a facility can "borrow" compliance procedures from seemingly unrelated industries.


The HON, the MACT standard for the synthetic organic chemicals and manufacturing industry, was in the two-year bin and set the tone for numerous MACT requirements that were later promulgated or are currently in the process of being formulated. Chemical facilities subject to the HON have had six years since its promulgation to optimize compliance. Many have fine-tuned internal systems in order to facilitate compliance assurance and demonstration. EPA has also made determinations on various issues ranging from initial applicability and applicability for controls to monitoring and record keeping. Facilities that are currently being impacted by new standards can certainly benefit from reviewing similar requirements that are contained in previously implemented MACT standards. By doing so, these facilities can streamline their MACT compliance activities.

Common cross-industry MACT compliance requirements and methodologies

MACT compliance requirements/methodologies

Subject industries

Biotreatment option for wastewater standards

Chemicals, pesticides, pulp and paper, polyols and polyethers, polymers and resins, etc.

Leak detection and repair requirements for fugitive components

Similar for synthetic organic chemicals and manufacturing industry, refineries, pharmaceuticals, pesticides manufacturing, etc.

Quantifying uncontrolled emissions from batch emission episodes; drawing up emission profiles for compliance testing

Common to pharmaceuticals, pesticides manufacturing, polymers and resins, polyols and polyethers, etc.

Requirements for closed vent systems

Similar for synthetic organic chemicals and manufacturing industry, pulp and paper, pharmaceuticals, pesticides manufacturing, etc.

Startup, shutdown and malfunction plans

Common to most industries


EPA introduction to CAA and section 112 (air toxics) — www.epa.gov/ttncaaa1/t3pfpr.html

EPA unified air toxics Web site: Rules & implementation (completed, proposed and upcoming) — www.epa.gov/ttn/uatw/eparules.html

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This article appeared in Environmental Protection magazine, May 2000, Vol. 11, No. 5, p. 26.

This article originally appeared in the 05/01/2000 issue of Environmental Protection.