TVA met with the Tennessee Department of Environment and Conservation on Wednesday to request a variance that would allow them to discontinue monitoring ambient sulfur dioxide (SO2) levels at six coal-fired power plants in Tennessee. The request was granted, and TVA will no longer monitor ambient SO2 at the facilities, which are:

• Bull Run
• John Sevier
• Johnsonville
• Kingston
• Cumberland
• Gallatin

TVA will still monitor point-source "smokestack" SO2 emissions at these facilities.

SO2 contributes to the formation of acid rain, which damages trees, crops, historic buildings, and monuments, and makes soils, lakes, and streams acidic affecting forests and wildlife. SO2 also contributes to the formation of atmospheric particles that cause visibility impairment, most noticeably in national parks.

The variance is a result of an October 2006 EPA rule change that relaxes standards for SO2 monitoring in areas where it is no longer believed needed.

Three conditions must be met to obtain a variance: (1) The actual sulfur dioxide emissions from a fuel burning installation do not exceed 20,000 tons per year; (2) The source must be located in an attainment area and must not significantly impact a sulfur dioxide nonattainment area; (3) Measurements of air quality in the vicinity of the source demonstrate that ambient sulfur dioxide levels do not exceed 75 percent of the ambient air quality standards for sulfur dioxide.

The good news is that TVA has significantly reduced SO2 emissions over the years and meets two of the three requirements. Ambient SO2 levels at these facilities are less than 25% of the SO2 air quality standards, and TVA has not violated ambient air quality standards at any of these facilities since 1993.

But, TVA does not meet the first requirement. In 2006, SO2 emissions exceeded 20,000 tons at all of these TVA facilities except Cumberland. Johnsonville is the worst offender at 86,800 tons, followed by Kingston at 55,500 tons. Total SO2 emissions for these six facilities were 242,200 tons in 2006.

TVA successfully argued before the EPA and TDEC that the 20,000 ton limit should not apply to them, stating "The reason that this requirement cannot be met is the fact that there are only seven coal fired power plants located within the State of Tennessee (six are listed above and the seventh is located in Shelby County and is unaffected by this variance). Consequently these power plants are very large by national standards. Thus, even burning lower sulfur coals, the actual sulfur dioxide emissions, measured in tons per year, will be very large." TDEC concurred and granted the variance.

While we applaud TVA's ongoing emission control efforts, this exemption does not appear consistent with the letter or the spirit of the weakened regulation. In fact, arguing that their facilities are too large to comply seems to defy logic.

A TDEC spokesperson provided background information on the hearing, which you can read after the jump. TDEC also forwarded a copy of TVA's request for variance, which you can read here.

(TDEC, Dec. 13, 2007): The United States Environmental Protection Agency established ambient air quality standards for a number of pollutants, including sulfur dioxide, in the 1970s. At that point in time, source sulfur dioxide emissions were much higher than they are today. In the 1970s, the Division established regulations that required certain large sources of sulfur dioxide emissions to conduct ambient monitoring for sulfur dioxide to determine if the air quality for the area surrounding the sources was achieving attainment with the newly established ambient air quality standards. The Tennessee Valley Authority has conducted ambient air quality monitoring for sulfur dioxide emissions around each of its coal-fired power plants since the 1970s.

On October 17, 2006, the United States Environmental Protection Agency published a revision to the federal regulations addressing ambient air quality monitoring. As a side issue in this final rule was a discussion of allowing the terminating of ambient sulfur dioxide monitoring for areas where the probability of a violation of the national ambient air quality standards for sulfur dioxide was remote.

In response to this revised federal rule, TVA petitioned the Technical Secretary to terminate ambient sulfur dioxide emission monitoring for the areas surrounding the six coal-fired power plants within the jurisdiction of this Division. The rationale for this is the fact that the last ambient air quality violation reported in the vicinity of any of the six coal-fired power plants occurred in 1980 and current ambient air quality data indicates that ambient sulfur dioxide levels for any of the six plants within the jurisdiction of this Division are less than 25% of any of the various ambient air quality standards for sulfur dioxide.

After reviewing the submittal, the Division agreed with the TVA request. The body of the variance (attached) contains a discussion of the regulations addressing ambient monitoring and notes that currently TVA meets three of the four criteria for terminating ambient air quality monitoring.

Here it must be noted that this request is not unique. A number of facilities were initially required to conduct ambient sulfur dioxide monitoring, and after demonstrating conformance with the requirements to terminate the monitoring they have received permission to terminate ambient sulfur dioxide monitoring.

Also this action only addresses the ambient air quality monitoring for the area surrounding the power plants. This action has no effect on the continuous in-stack monitoring of sulfur dioxide emissions from the exhaust gas streams of the power plants. The in-stack monitoring is addressed by different regulations and emissions data and can be found here.