EPA Admits Error in Proposed Mercury MACT Rule

May 25, 2011 - Power News (http://bit.ly/iC00D9):

The Environmental Protection Agency (EPA) has acknowledged in a letter to non-profit power trade organization Utility Air Regulatory Group (UARG) that it made a conversion error in the way mercury emissions data was calculated to set limits for the agency’s mercury maximum achievable control technology (MACT) floor in the proposed Mercury and Air Toxics Standards (MATS) rule. 

EPA Assistant Administrator for Air and Radiation Gina McCarthy wrote that the error would be corrected and results presented within a week, but that the corrections were not expected to have an “appreciable impact” on the pollution controls required to meet the new standards. 

The group had said in a May 6 letter to the EPA that the MACT rule is one of the "most far-reaching and expensive rules" the agency had ever proposed under the Clean Air Act. The EPA asked for information of "unprecedented size and scope," including historic information on hazardous air pollutants that required electric generating units to conduct more than $100 million of stack sampling for emissions. 

The UARG said it was concerned that the EPA had not allotted enough time to review all the data collected. A review of the information in the "limited time" made available for public comment showed several errors that "warrant withdrawal of the current proposal, re-analysis of the data, and re-proposal once the errors have been addressed." 

One glaring error regarding MACT standards for mercury was that the EPA concerned how the EPA converted historical emissions data to common emission units. "Specifically, the conversion factor EPA used to convert measurements reported in terms of lb/GWh to lb/MWh is incorrect by a factor of 1,000," the group asserted. "As a result, the emissions of the unit chosen as the single best performing mercury source are actually 1,000 times higher than those EPA assumed in setting the new source MACT limit for mercury." 

The group also charged that the conversion error pervades EPA's mercury MACT floor analysis for existing units. "At least half of the 40 units identified as 'best performing' have actual emissions 1,000 times higher than EPA used in its MACT floor analysis."  

The UARG also found errors in the EPA's MACT limits for mercury for units designed to burn coal. For units burning coal of more than 8,300 BTH/hour, the limit is 1.0 lb/10 BTU or 0.008lb/GWh. But the "required heat rate to convert from the proposed input limit to the proposed output limit is 8,000 BTU/KWh, which is unrealistically low value for a coal-fired power plant," the group said. 

Addressing that concern, McCarthy said in her letter on Thursday that revised calculations resulted in only a slight increase of that limit, however, from 1.0 to 1.2 pounds per BTU. "We estimate that this change will lessen our expected mercury reductions by about half of a ton, not changing our projected 90 percent reduction from the mercury in the coal used by power plants." 

McCarthy also acknowledged the UARG's concerns as "possible discrepancies" regarding the EPA's calculations, and she said the EPA would "fully consider" the UARG's comments and other comments provided during the comment period. 

"We have revised these mercury calculations and will include them in the docket this week to ensure that this information is publicly available," she wrote. "We do not expect this change to have any appreciable impact on the controls that will be needed for compliance or on the analyses underlying the proposal."

Sources: POWERnews, EPA, UARG, www.vnf.com

Boiler MACT Effective Date Delayed...

May 16, 2011 - The EPA has announced the next step on air toxics standards for boilers and certain incinerators. The agency is allowing time to seek and review additional public input on new standards.  Potential compliance activities for the rule include work practice standards, fuel analysis (additional options currently under consideration) and performance testing (stack tests).

Boiler MACT site: http://www.epa.gov/airquality/combustion


Fact Sheet: http://www.epa.gov/airquality/combustion/docs/20110516nextstepfs.pdf

Notice: http://www.epa.gov/airquality/combustion/docs/20110516nextstep.pdf

Action:

• On May 16, 2011, EPA announced its next step in allowing time to seek and review additional public input on the final standards for boilers and certain solid waste incinerators issued in February 2011.
• Following the April 2010 proposals, the agency received more than 4,800 comments from businesses and communities, including a significant amount of information that industry had not provided prior to the proposals. 
• Based on this input, EPA made extensive revisions to the standards. For example, EPA made revisions to the proposed subcategories and to some of the proposed emissions limits.  
• In December 2010, EPA requested additional time for review to ensure the public’s input was fully addressed.  However, the court granted EPA only an additional 30 days, resulting in the February 2011 final rules.
• The agency is reconsidering the standards because the public did not have sufficient opportunity to comment on these changes, and, as a result, further public review and feedback is required to meet the legal obligations under the Clean Air Act.   
• EPA is also issuing a stay to delay the effective date of the standards for major source boilers and commercial and industrial solid waste incinerators. The stay will allow the agency to seek additional public comment before requiring thousands of facilities across multiple, diverse industries to make investments that may not be reversible if the standards are revised following reconsideration and a full evaluation of all relevant data.  
• The stay will remain in place until the proceedings for judicial review of these rules are completed or EPA completes its reconsideration of the standards, whichever is earlier. 
• EPA understands that members of the public may wish to submit additional data. Any additional data and information related to affected sources and their emissions that the public would like the agency to consider should be submitted by e-mail to combustionsurvey@erg.com by July 15, 2011.   
• This approach will help ensure that the final standards are protective, cost-effective, practical to implement and consistent with the requirements of the Clean Air Act.

EPA Revisions to Method 301 Validations

On May 10, 2011 the U.S. Environmental Protection Agency issued a revision to its Method 301 Validation process. Method 301 is used when a source owner or operator proposes to use a new or alternative source emissions sampling method to meet an EPA compliance requirement for stack testing.  The method specifies procedures for determining and documenting the precision and bias of measured concentrations from various media (e.g., sludge, exhaust gas, and wastewater) at the level of an applicable standard for a source. 

Revised Rule: http://www.epa.gov/ttn/oarpg/t3/fr_notices/20110512method301.pdf.

Fact Sheet:  http://www.epa.gov/ttn/oarpg/t3/fact_sheets/20110512method301fs.pdf

Method 301 affects/applies to you if you want to propose a new or alternative test method to meet an EPA compliance requirement.

You would use Method 301 whenever you propose to use a test method to meet an EPA compliance requirement other than a method required under a 40 CFR part 63 rule. The method specifies procedures for determining and documenting the precision and bias of measured concentrations from various media (e.g.,

sludge, exhaust gas, wastewater) at the level of an applicable standard for a source. Bias (or systemic error) is established by comparing your proposed method against a reference value. A correction factor is employed to eliminate/minimize bias. This correction factor is established from data obtained during your validation test. Methods that have bias correction factors outside a specified range are considered unacceptable. Method

precision (or random error) at the level of the standard must be demonstrated to be as precise as the validated method for acceptance.

EPA proposed five major technical changes to Method 301. These technical changes include the following:

1. Replacing the Practical Limit of Quantitation (PLQ) with a procedure to determine the Limit of Detection (LOD)
2. Revising the bias acceptance criteria and eliminating correction factors
3. Revising precision acceptance criteria when using analyte spiking
4. Allowing analyte spiking even when there is an existing test method
5. Establishing new procedures for ensuring sample stability

Other clarifications from EPA include:

• Amendments to Method 301 do not apply to methods submitted for approval prior to promulgation.
• Method 301 can be used whether or not a validated method exists.
• Inadvertantly, in Section 5 of Method 301, “reference materials” was followed by “(analytes).” This parenthetical was modified for clarification purposes.
• A few commenters expressed concern that the standard against which precision and bias are compared is not required to be compared against a true value, usually a traceable standard. EPA agreed that the reference material should be compared to a traceable standard.
• EPA has approved methods demonstrated with sequential sampling to determine the precision of a proposed alternative method in the past. The final method explicitly states that sequential sampling procedures are allowed.
• If an alternative method is being compared to a validated test method as part of the Method 301 validation and an audit sample for the validated method exists, then an audit should be used for the validated method.
• Method 301 previously lacked specific procedures for ensuring that samples collected under proposed alternative methods were analyzed within an appropriate time. EPA revised Section 7.4 to include a requirement to calculate the difference in the sampling results at the minimum and maximum storage times, determine the standard deviation of the differences, and test the difference in the results for statistical significance by calculating the t-statistic and determining if the mean of the differences between the initial results and the results after storage is significant at the 95 percent confidence level.  The method will continue to require a precision of ± 20 percent when only the required three runs per test are performed. However, EPA have added an option to allow test methods with a precision greater than ± 20 percent, but less than ± 50 percent, provided that the user collect nine sample runs per test during any compliance testing where the method is used.
• EPA proposed to replace the Practical Limit of Quantitation (PLQ) determination with a procedure to determine the Limit of Detection (LOD), and clarified the terms and equations for that procedure.