Monitoring Networks

TVA's Air Quality Monitoring Networks Promote a Cleaner and Greener Nation and Region

For much of the first half of the 20th century, billowing smokestacks were an unmistakable sign of industrial might and economic prosperity. Smoke meant jobs. Air pollution problems, when considered at all, were thought of as isolated concerns having little or no relevance to the general public.

Then came the deadly air pollution episodes in Donora, Pennsylvania in October 1948, and in London, England, in December 1952. The collective solution to these air pollution problems, in great part, was to build taller smokestacks and to move industries to more isolated rural areas. The singsong environmental management maxim of the day was "The solution to pollution is dilution."

Somewhere along the way we ran out of these dilution options and air quality—along with water quality and solid waste—became cornerstones of the emerging U.S. environmental conscience. The 1970 Clean Air Act Amendments, along with the establishment of the U.S. Environmental Protection Agency (EPA) in that same year, were defining moments in the history of air quality. Now, at long last, the country had focused its collective environmental conscience by establishing clean air objectives and regulatory guidelines to help achieve these objectives. Some of EPA's current "criteria air pollutants" and their present standards for compliance are listed in Table 1.

TVA Air Monitoring History

TVA's contributions to air quality monitoring and research began in the early 1950s with the construction of the second TVA-built, fossil-fired power pant near Johnsonville, Tennessee, where TVA initiated a comprehensive air pollution studies program. Sulfur dioxide (SO2) and particulate matter (PM) pollution were the principal concerns.

Among TVA "firsts" in these early years were a series of investigations in removing SO2 from power plant plumes from 1952 to 1955; an acid rain study—The Southern Regional Sulfur Project—beginning in 1953 at the TVA Colbert Plant in northwestern Alabama; the adaptation and use of automated air quality monitoring equipment for helicopter and car (mobile) sampling in 1956; a 5-year plume dispersion study beginning in 1957; and routine air quality and biological monitoring and surveillance before, during, and after the construction and operation of new TVA power plants.

The 1960s brought more "firsts," with plume rise studies in 1963, taller smokestacks, and the implementation of fully automated meteorological and air quality monitoring networks in the late 1960s. During the 1960s and 1970s, TVA installed high-efficiency (90 to 95%) electrostatic precipitators on newer fossil plants and retrofitted older plants. Evolutionary improvements in PM controls at TVA fossil plants now achieve efficiencies of more than 98%.

From the late 1960s through the mid-1970s, TVA operated more than 130 air quality monitoring stations near the Agency's 11 fossil-fired power plants and at the (then named) National Fertilizer Development Center in Muscle Shoals, Alabama. Most of this monitoring was associated with the TVA Sulfur Dioxide Emissions Limitation (SDEL) Program.

When TVA adopted continuous SO2 emission control strategies in the late 1970s, the need for air quality monitoring declined, as the areas around TVA facilities came into compliance with clean air standards. While TVA's compliance monitoring needs diminished throughout the 1980s and 1990s, the Agency's commitment to assessing new and emerging air quality issues increased.

Compliance Monitoring

TVA currently operates eleven compliance air quality monitoring stations. Nine stations in Alabama and Tennessee measure hourly levels of SO2 near TVA power plants to demonstrate continuing compliance with clean air standards (Figure 1). Not a single violation of SO2 standards has occurred at these stations for more than a decade, as TVA continues to reduce its SO2 emissions.

The two Kentucky "compliance" monitoring stations are ozone monitoring stations operating in-lieu-of SO2 monitoring stations at the TVA Paradise and Shawnee fossil power plants. Once TVA demonstrated compliance with SO2 clean air standards, the Kentucky Division for Air Quality determined that regional ozone monitoring (at the Land Between The Lakes National Recreational Area and at Hopkinsville, Kentucky) was of greater value to Kentucky's clean air goals. These two stations collect hourly ozone levels during the 8-month Kentucky ozone season (March-October).

Ozone Monitoring

In the mid-1980s, ozone (O3) pollution emerged as a major issue. In 1988, TVA partnered with the Tennessee Department of Environment & Conservation (TDEC) to initiate the Middle Tennessee Ozone Study (MTOS) in and around Nashville, Tennessee. Timing, it is said, is everything, and the summer of 1988 turned out to be the worst ozone season on record for the south-central United States. Eventually, this 8-station MTOS partnership network became part of the Nashville/Middle Tennessee area ozone compliance network operated by TDEC and the Nashville/Davidson County Health Department.

Ozone pollution continues to be a significant environmental issue for the south-central United States. The 8-hour ozone standard of 0.08 parts-per-million (added in 1997) will prove most challenging to meet and maintain. TVA currently supports the operation of seven ozone monitoring stations across the Tennessee Valley.

Acid Rain Monitoring

Acid rain emerged as a major environmental issue in the late 1970s and early 1980s. TVA's modern-era acid rain monitoring program, which was initiated in 1978, eventually merged with the National Acid Precipitation Assessment Program (NAPAP) in the mid-1980s. As part of NAPAP, TVA was a major participant in the Mountain Cloud Chemistry Monitoring Program, as well as numerous acid deposition research programs. Today, TVA, in partnership with other federal agencies and regional universities, continues to support five Valley long-term acid rain monitoring stations as part of the National Atmospheric Deposition Program.

Fine Particle Monitoring

Attaining compliance with the particulate matter clean air standards for "fine" particles (those less than 2.5 micrometers in diameter) will prove to be a daunting environmental challenge for the south-central United States. TVA scientists first measured fine particle levels in 1982, as part of TVA's Visibility Monitoring Program. This past year, TVA and its Valley regulatory partners completed the operation of a 9-station fine particle monitoring network. While this 9-station network has now merged with the EPA-supported state and local compliance monitoring network, TVA continues to collect fine particle monitoring data at the Agency's research and economic development air quality monitoring stations. TVA currently supports three fine particle monitoring stations.

Research Monitoring

In partnership with EPA and the National Park Service (NPS), TVA, in 1980, founded the first research visibility monitoring station in the Eastern United States at Look Rock on the western edge of the Great Smoky Mountains National Park. Although that project ended in 1984, this station continues to be used by TVA, NPS, and others for visibility, fine particle, and ozone monitoring and research.

Today, TVA supports three special-purpose research oriented monitoring stations, two in the Great Smoky Mountains National Park (Look Rock and Cove Mountain) and one at Mammoth Cave National Park. These high-sensitivity monitoring stations focus on a number of regional air quality issues, including visibility impairment, ozone, acid rain, air toxics, and fine particles.

Monitoring for Economic Development

The 1977 Amendments to the Clean Air Act addressed a new area of concern--preventing deterioration of air quality in places where air quality is already better than national clean air standards. The intent of this "prevention of significant deterioration" (PSD) legislation was twofold. First, it would help preserve air quality in "Class I" areas—national parks and wilderness areas. Second, it would ensure that new or expanding industries did not compromise air quality in other areas of the country meeting national clean air standards—"Class II" areas. In short, the PSD program was enacted to ensure that economic growth would occur in a manner that would not cause deterioration of existing clean air resources. Under PSD legislation, states require that major industrial expansion or new construction be subjected to a review of the potential impact on air quality. This review is part of the application for a construction permit. The PSD process requires both an assessment of existing baseline air quality and an estimate of additional pollution that could be contributed by the proposed construction. If the added burden of pollution appears to be too great, more stringent pollution controls will be required.

If no recent data are available on baseline ambient air quality, potential sources may be required to collect up to one year's ambient monitoring data for the regulated pollutants. For companies eager to commence construction, this can pose a serious delay. And with the fierce competition that exists across the country to draw new industries, any area that has available air quality data surely has a significant competitive advantage.

Each year, TVA meets with Valley state environmental regulators and economic development agencies to establish priority sites for these stations. In 1993, the first three TVA/state economic development special purpose monitoring stations were installed. With the addition of more stations, this program has, to date, collected 30 station-years of baseline air quality data for economic development purposes at 22 locations across four Valley states (Figure 2). These data often represent the only air quality data available for an area. Pollutants measured at these stations include SO2, ozone, nitrogen oxides, carbon monoxide and fine particulate matter. This program has successfully supported the construction of environmentally appropriate new and expanding industries.

Conclusions

Data from TVA-supported air quality monitoring networks benefit the Tennessee Valley and the nation in many ways. In addition to measuring compliance with clean air standards, these first-class air monitoring programs are often on the leading edge of air quality science. While TVA is ever mindful of past accomplishments, the Agency's focus remains on the future and on helping to bring both economic prosperity and enhanced environmental quality to the Tennessee Valley.

Information Contacts

William J. Parkhurst
(256) 386-2793
wjparkhurst@tva.gov

Frances P. Weatherford
(256) 386-2344
fpweatherford@tva.gov

Bonnie S. Ginn
(256) 386-3565
bsginn@tva.gov

Last updated on 8-10-2002.
Inquiries and comments should be sent to wjparkhurst@tva.gov.