### 1 

### Why EPA Should Not Establish Numerical Dioxin /Furan Limits in the Industrial Boiler MACT and Certain CISWI Dioxin/Furan Limits Should be Adjusted (July 15, 2011)

In March 2011, EPA finalized numerical dioxin /furan (D/F) standards for 12 subcategories of industrial boilers and process heaters and for 5 CI SWI subcategories. Mo st of the limits are lower than any other D/F standar ds EPA has set in the past for various waste combustion source categories (see attachment titled: Compar ison of Dioxin Emission Limits in Various U.S. Regulations). EPA should set work practice require ments instead of numerical D/F

standards for industrial boilers and should adjust certain of the CISWI D/F standards to account for measurement uncertainty for the reasons outlined below.

The majority of the data collected in order to set the D/F standards for industrial boilers and CISWI energy recovery units are at levels below the capability of the analytical and stack

test methods to detect emissions of these compounds (all but one of the test runs used to set
the Boiler MACT limits are marked as “detection le vel limited”). Much of the test data are labeled as being below the me thod detection limit and the rema inder of the data are often flagged as being below the leve l the laboratory feels can be reported with confidence.

It is not appropriate to treat detection level limited data for purposes of establishing regulatory limits in the same manner as detected values because the uncertainty 1 

### associated

with measurements near or below the method detection limits is too high. The test methods were developed over 30 years ago to measure D/F at concentrations then found in some types
of waste incinerator exhaust (levels orders of magnitude hi gher than those found in exhaust from today’s industrial boilers and CISWI energy recovery units).

All source emission measurements have random (precision) errors associated with the sample collection, sample and equipment handling, samp le preparation, and sample analysis. These errors define method detection and quantitation limits and uncertainty in a non-arbitrary, scientific manner (as discussed fu rther below). When emission le vels are much higher than the magnitude of these errors , there is a high degree of confidence in the measured value obtained from a single or a few test runs . However, as the measured val ue decreases, the contribution of these errors to the measured value increases, thus decreasing the confidence level in the accuracy of the measured value from a si ngle or a few runs until the point where the measured value cannot be distinguish ed from the random error (“noise” level). This is the case with
the boiler D/F data and much of the CISWI D/ F data. When this occurs, the measurement cannot be distinguished from zero with high confidence.

The magnitude of D/F m easurement errors typically varies with every measurement and is affected by the characteristi cs of the sample, skills of the sampler and analyst, specific equipment used, techniques and procedures adopt ed by individual laboratories and other factors even when following the same published test method (in this case, EPA Method 23).

1 

### Uncertainty here refers to the statistical expression of measurement error, such as defined in ASME Performance Test Code 19.1, rather than an inference of something which is unknown.

### 2 

### Although EPA Method 23 procedures minimize measurem ent errors at the stack emission levels and applications for which it was intended, measurement errors are not zero and become significant at the extremely low levels in industrial boilers and CISWI energy recovery units.

In setting the Boiler MACT and CISWI standards, EPA has acknowledged that the emission limit should not be set below the capability of the appl icable test method. However, EPA did not use the widely accepted definition of method detection limit, which is based on the capabilities of multiple commercial laboratories to analyze a sa mple and identify the presence of a chemical above the “noise” level. In its place, EPA co ined a new term, representative method detection limit (RDL) to define a measur ement method detection limit wh ich is based on the laboratory detection limits reported for the test s with the lowest emissions. This erroneous methodology resulted in estimating D/F de tection limits that are over 100 times lower than those regularly achieved by commercial laboratories

. The detection limit of an analytical method is commonly defined as th e lowest concentration that can be distinguished from replicat e blanks. The quantitation limit of a method is defined as the
smallest concentration of t he substance which can be measur ed with an acceptable level of uncertainty . Detection limits and quantit ation limits are def ined in a scientific, non-arbitrary manner in various widely-published peer-reviewed consensus guidelines 2 

### and EPA documents.
Quantitation limits of test methods have great significanc e when measuring very low concentrations of pollutants. In practice, reported values below the method's quantitation
limit should not be treated as real values

. The majority of a federal advisory commi ttee on method detection and quantitation limits recommended that the quantitati on limit of a test method should be based on the 95 th 

### percentile of what is being achieved by the commercial laboratories 3 

### . Using this approach and rounding up the quantitation limit to a single digit, as EPA has done for floor setting, would result in a D/F TEQ quantitation limit of 0.2 ng/ dscm based on analytical procedures alone. However, using
the results of t he ASME ReMAP study 4 

### , which evaluated the precision of Method 23 D/F stack testing measurements, a D/F TEQ quantitation limit of 0.27 ng/dscm is derived, which addresses the uncertainty of all of the test method components. Thus, if numerical D/F standards are set pursuant to Section 129, EPA should not set CI SWI D/F TEQ emission standards at less than 0.3 ng/dscm

. In EPA’s recently proposed Utility MACT, no diox in/furan standards are proposed for coal and oil-fired EGUs because the majo rity of the data are below me thod detection and/or reporting limits (“non-detect,” or ND). The levels of D/F reported by industrial boilers are very low, similar to utility boilers . EPA states in the Utility MACT pream ble, “Overall, the available test

2 

### For example, Keith, L.H. et al., Principles of Environmental Analysis, Anal. Che m. 1983

, 55 , 2210-
2218.

3 

### Report of the federal advisory committee on detection and quantitation approaches and uses in Clean Water Act Programs submitted to the Envi ronmental Protection Agency (EPA). December
2007.

4 

### Lanier, W.S. and Hendrix, C.D. Final Report -- Re ference Method Accuracy and Precision (ReMAP): Phase 1 Precision of Manual Stack Emission Meas urements, ASME International, Washington, D.C. (2001).

### 3 

### methods are technically challenged, to the point of providing results that are questionable for all of the organic HAP. 5 

### ”

The Utility MACT preamble indicates that EPA believes D/F formation is inhibited by the lack of precursors such as available chlorine or by a high sulfur-to-chlorine ratio 6 

### . The same principles apply for some industrial boilers and pr ocess heaters. For exampl e, coal and residual oil-fired boilers will have high sulfur to chlorine ratios and some types of biomass boilers will have low available chlorine. Many industrial boiler designs and fuels typically exhibit other conditions inhibiting D/F formati on, such as low unburned carbon and catalyzing elements in the fuels, high combustion temperatures, and s hort gas residence times at critical lower temperatures.

One-time stack test data from only 1 or 2 units are being used to set D/F limits for each subcategory. Even if the D/F test methods were not being stretched beyond their limits, this approach does not provide emissi ons data representative of the normal range of operations and fuel compositions, ambient environmental condi tions, geographic locations and other factors that may influence air pollutant emissions. The performance of the top 12 percent of all CISWI units cannot be determined using only a few data points

. As demonstrated by the m easurement issues noted, quantifying the actua l, extremely low or
non-existent dioxin emission levels for the Bo iler MACT floor units is technologically impracticable (as well as economically im practicable, given that the technological problems cannot be overcome by investing r easonable resources into the problem), and thus, it is not feasible to pr escribe or enforce an emission standard for D/F emissions for

these units. Clean Air Act Section 112(h)(1) supports es tablishing a work practice standard for D/F in the Boiler MACT, as was done in the rec ently proposed Electric G enerating Unit (“Utility”)
MACT rule 7 

### . The required tune-ups and other emissions reductions in the Industrial Boiler MACT will result in improved combustion and mi nimize conditions conducive to D/F formation without establishing a numeric al emission standard.

Several sets of comments have been submitted t hat provide more detail on these points:

o AF&PA Comments at EPA-HQ-OAR-2002-0058-3213 and reconsideration petition (see in particular Appendix A) at EPA-HQ-OAR-2002-0058-3293

o CIBO Comments at EPA-HQ-OAR-2002-0058-2702

o ACC Comments at EPA-HQ-OAR-2002-0058-2792

o API/NPRA Comments at EPA-HQ-OAR-2002-0058-2935

o CRWI Comments at EPA-HQ-OAR-2002-0058-2824

o NCASI Comments at EPA-HQ-OAR-2002-0058-2804 and additional detail in a paper to be submitted to EPA on July 15, 2011

o ENVIRON Comments at EPA-HQ-OAR-2002-0058-2809

5 

### 76 FR 25040

6 

### 76 FR 25023

7 

### 76 FR 2497640.0010.010.11101001000 Municipal Waste Incinerators Class II Unit Other SW Incinerators Municipal Waste Incinerators Class I Existing Units Hosp/Med/Inf Waste Incinerators Small Older Units Municipal Waste Incinerators New Units Sewage Sludge Incinerators Existing Units Hosp/Med/Inf Waste Incinerators Small Existing Unit Hosp/Med/Inf Waste Incinerators Medium Hosp/Med/Inf Waste Incinerators Large Haz Waste Combustor MACT Existing Sources w/o dry ... CISWI ERU Existing Liq/Gas Boiler MACT Biomass Suspension Burners Portland Cement Kiln MACT Haz Waste Combustor MACT 2011 CISWI Existing Incinerators Haz Waste Combustor MACT New Sources Boiler MACT Gas 2 CISWI ERU Existing Bio/Coal Hosp/Med/Inf Waste Incinerators Large New Proposed PVC MACT Process Vents Boiler MACT Biomass FB Hosp/Med/Inf Waste Incinerators Small New Boiler MACT Biomass Stoker Boiler MACT Existing Coal pulverized Boiler MACT Existing Coal stoker Boiler MACT New Biomass Fuel Cell Boiler MACT New Coal pulverized Boiler MACT New Coal stoker Sewage Sludge Incinerators New Units Boiler MACT Coal FB Boiler MACT New Oil

Dioxin Limit, ng/dscm @ 7% O2ComparisonofDioxinEmissionLimitsinVariousU.S.RegulationsCategory 2000Emissions,g/yrTEQBackyardbarrelburning 498.5HMIWI 378MWI 83.8CoalUtilityBoilers 69.5MetalSmelting/Refining 43.92011BoilerMACTdata 37.2Cementkilns 36Residential wood/oilcomb. 15.80.3ng/dscmD/FTEQquantitation limit