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Date: December 14, 2011

Subject: Calculation of Representative Detection Levels for Metals, Particulate Matter, and

Hydrochloric Acid Emissions; Electric Utility Steam Generating Units MATS

From: Roy Neulicht (RTI International)

To: Bill Maxwell

OAQPS/SPPD/ESG (D243-01)

U.S. Environmental Protection Agency

Research Triangle Park, NC 27711

Introduction

This memorandum documents the calculation of representative detection levels (RDL) as 

emission rates, pound per million Btu (lb/MMBtu) for metals, filterable particulate matter (PM), 

and hydrochloric acid (HCl) emissions. A December 13, 2011, memorandum from Peter Westlin

and Ray Merrill, US EPA, Office of Air Quality Planning and Standards entitled “Data and 

procedure for handling below detection level data in analyzing various pollutant emissions 

databases for MACT and RTR emissions limits,” provides guidance for the handling of below 

detection level (BDL) data and for developing RDL data. The referenced memorandum provides 

several tables that present RDLs for various pollutants in units of mass and concentration for 

representative sampling times. For the EGU MATS rule, RDLs expressed in terms of emissions 

rate, lb/MMBtu are needed. The purpose of this memorandum is to document the calculations

used to convert the RDLs for PM, HCl, and metal emissions presented in the referenced 

memorandum in terms of concentration, microgram per dry standard cubic meters (μg/dscm) to 

an emission rate, lb/MMBtu. 

Calculations

Except for IGCC units, the following equation was used to convert RDLs expressed as μg/dscm 

to units of lb/MMBtu:

E = Cd * Fd * (20.9 / (20.9 - % O2))

Where:

E = Emissions rate, lb/MMBtu

Cd = concentration (lb/dscf)

Fd = F Factor, dscf/MMBtu

% O2 = percent oxygen in flue gas

Conversion: 1 lb/scf = 1.6 x 1010μg/dscm
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An oxygen content of six percent (6 %) was used for the calculations.

For IGCC units, the information available was the Fc and flue gas carbon dioxide concentrations. 

Therefore, for IGCC units, the following equation was used to convert RDLs expressed as 

μg/dscm to units of lb/MMBtu:

E = Cd * Fc * (100 / % CO2)

Where:

E = Emissions rate, lb/MMBtu

Cd = concentration (lb/dscf)

Fc = F Factor, scf/MMBtu

% CO2 = percent carbon dioxide in flue gas

Conversion: 1 lb/scf = 1.6 x 1010μg/dscm

An Fc value of 2,313 scf/MMBtu was used for the calculations. This Fc value is the average of 

the Fc values available from the two IGCC units in the MATS project database. A carbon dioxide 

content of nine percent (9 %) was used for the calculations. 

Results

The results are calculated and reported as three times (3x) the RDL because EPA’s guidance is to 

compare the calculated MACT floor to three times the RDL value, and to use the higher of the 

two values. Tables 1, 2, and 3 present the results for Method 29 metals, filterable PM, and HCl, 

respectively. Note, to convert the calculated RDL values from units of lb/MMBtu to units of 

lb/MWh, we derived a conversion factor of 10 MMBtu/MW from the 2010 EU MACT ICR data. 

This is an average factor derived from data and was needed so the minimum RDLs calculated in 

accordance with Method 19 could be compared to the output based UPLs in units of lb/MWh. 

For all coal, oil and pet coke, we used a 3 x RDL value of 6.4E-4 for PM and 4.0E-5 for HCl.
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Table 1. Calculation of Three Times the Representative Detection Level for Metals for Method 29 

Method 29 Metals 3 x Representative Detection Level (RDL), 4 dscm sample volume

μg/dscm lb/dscf lb/MMBtu at 6% O2 lb/MMBtu at 9% CO2

All Coal Oil Pet coke IGCC

Fd, Fc = 9,780 9,190 9,830 2,313

Antimony 8.3E-01 5.1E-11 7.1E-07 6.6E-07 7.1E-07 1.3E-06

Arsenic 3.0E-01 1.9E-11 2.6E-07 2.4E-07 2.6E-07 4.8E-07

Beryllium 6.0E-02 3.7E-12 5.1E-08 4.8E-08 5.2E-08 9.6E-08

Cadmium 2.3E-02 1.4E-12 1.9E-08 1.8E-08 1.9E-08 3.6E-08

Chromium 2.3E-01 1.4E-11 1.9E-07 1.8E-07 1.9E-07 3.6E-07

Cobalt 2.3E-01 1.4E-11 1.9E-07 1.8E-07 1.9E-07 3.6E-07

Lead 2.3E-01 1.4E-11 1.9E-07 1.8E-07 1.9E-07 3.6E-07

Manganese 2.3E-01 1.4E-11 1.9E-07 1.8E-07 1.9E-07 3.6E-07

Nickel 4.1E+00 2.5E-10 3.5E-06 3.3E-06 3.5E-06 6.5E-06

Selenium 6.0E-01 3.7E-11 5.1E-07 4.8E-07 5.2E-07 9.6E-07

total 5.8E-06 5.4E-06 5.8E-06 1.1E-05
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Table 2. Calculation of Three Times the Representative Detection Level for Filterable Particulate Matter

Sample Volume 3 x Representative Detection Level (RDL), 4 dscm sample

dscm μg/dscm lb/dscf lb/MMBtu at 6% O2 lb/MMBtu at 9% CO2

All Coal Oil Pet coke IGCC

Fd, Fc = 9,780 9,190 9,830 2,313

1 3000 1.9E-07 2.6E-03 2.4E-03 2.6E-03 4.8E-03

2 1500 9.4E-08 1.3E-03 1.2E-03 1.3E-03 2.4E-03

3 1000 6.2E-08 8.6E-04 8.0E-04 8.6E-04 1.6E-03

4 750 4.7E-08 6.4E-04 6.0E-04 6.5E-04 1.2E-03

Table 3. Calculation of Three Times the Representative Detection Level for HCl

Sample Volume 3 x Representative Detection Level (RDL), 4 dscm sample

dscm μg/dscm lb/dscf lb/MMbtu at 6% O2 lb/MMBtu at 9% CO2

All Coal Oil Pet coke IGCC

Fd, Fc = 9,780 9,190 9,830 2,313

1 1.8E+02 1.1E-08 1.5E-04 1.4E-04 1.5E-04 2.9E-04

2 9.0E+01 5.6E-09 7.7E-05 7.2E-05 7.7E-05 1.4E-04

3 6.0E+01 3.7E-09 5.1E-05 4.8E-05 5.2E-05 9.6E-05

4 4.5E+01 2.8E-09 3.9E-05 3.6E-05 3.9E-05 7.2E-05