4694 Federal Register / Vol. 69, No. 20 / Friday, January 30, 2004 / Proposed Rules 

process type in this rule (bituminous 

coal, subbituminous coal, lignite coal, 

coal refuse, and IGCC). 

The EPA’s review of the available 

emission data shows that Hg emissions 

from new coal-fired units can be 

reduced to the following:

Bituminous units: 0.61 lb/TBtu heat 

input; 

Subbituminous units: 2.0 lb/TBtu heat 

input; 

Lignite units: 6.3 lb/TBtu heat input; 

Waste coal units: 0.11 lb/TBtu heat 

input; 

IGCC units: 2.0 lb/TBtu heat input.

Mercury emissions from new oil- and 

gas-fired units are not covered by the 

proposed rule. 

Subpart Da Ni emission standards. In 

selecting a regulatory approach for 

formulating emission standards to limit 

Ni emissions from new oil-fired steam 

generating units, the performance on Ni 

of the PM control technologies 

discussed above were considered. The 

technical basis (i.e., BDT) selected for 

establishing Ni emission limits for new 

sources is the use of ESP units or oils 

low in Ni content. 

The EPA’s review of the available 

emission data shows that Ni emissions 

from new oil-fired units can be reduced 

to 84 lb/TBtu heat input.

5. What Are the Subpart Da Hg and Ni 

Emission Standards? 

Based on available performance data 

analyses from the 1999 ICR for coalfired Utility Units, the Administrator 

has concluded that the application of 

fabric filters or ESP units along with wet 

or dry FGD is considered to be the most 

effective Hg control technology for units 

firing subbituminous, lignite, or waste 

coals; and that the application of fabric 

filters or ESP units, wet or dry FGD 

systems, and SCR is considered to be 

the most effective Hg control technology 

for units firing bituminous coals. For 

IGCC units (regardless of coal rank 

fired), the Administrator has concluded 

that use of a carbon bed is considered 

to be the most effective Hg control 

technology. These controls represent the 

best system of emissions reductions 

(taking into consideration the cost of 

achieving such emissions reductions, 

any non-air quality health and 

environmental impact, and energy 

requirements). 

Based on available performance data 

and cost analyses, the Administrator has 

concluded that the application of ESP 

units or oils containing a low Ni content 

is considered to be the most effective Ni 

control technology for oil-fired units. 

These controls represent the best system 

of emissions reductions (taking into 

consideration the cost of achieving such 

emissions reductions, any non-air 

quality health and environmental 

impact, and energy requirements). 

6. How Did EPA Select the Format for 

the Proposed Standards? 

Based on the analyses and discussion 

presented earlier, EPA has selected an 

output-based format for the proposed 

new-source rule. The Administrator is 

proposing today Hg emission limits for 

new coal-fired Utility Units as follows:

Bituminous units: 0.0060 GWh gross; 

Subbituminous units: 0.020 lb/GWh 

gross; 

Lignite units: 0.062 lb/GWh gross; 

Waste coal units: 0.0011 lb/GWh gross; 

IGCC units: 0.020 lb/GWh gross.

Based on the available performance 

data, cost analysis, and the above 

calculation, the Administrator is 

proposing today Ni emission limits for 

new oil-fired Utility Units as follows: 

0.0008 lb/MWh gross. 

7. How Did EPA Determine Testing and 

Monitoring Requirements for the 

Proposed Standards? 

The CAA requires EPA to develop 

regulations that ensure initial and 

continuous compliance. Testing and 

monitoring requirements allow EPA to 

determine whether an affected source is 

operating in compliance with an 

applicable emission limitation/standard. 

This section discusses how EPA 

selected the proposed testing and 

monitoring requirements used to 

determine compliance with the Hg and 

Ni emission limits that are specified in 

the proposed rule. 

Mercury testing and monitoring 

requirements. The proposed rule would 

establish Hg emission limits for coalfired units. The format selected for these 

Hg emission limits is a 12-month rolling 

average Hg emission level expressed in 

units of lb/TBtu or lb/MWh. Therefore, 

appropriate testing or monitoring 

requirements for determining the 

amount of Hg emitted from an affected 

unit throughout the compliance 

averaging period must be included in 

the rule. 

The most direct means of 

demonstrating compliance with an 

emission limit is by the use of a CEMS 

that measures the pollutant of concern. 

The EPA considers other testing or 

monitoring options when acceptable 

CEMS are not available for the intended 

application or when the impacts of 

including such CEMS requirements in 

the proposed rule are considered by 

EPA to be unreasonable. In determining 

whether to require the use of other 

testing or monitoring options in lieu of 

CEMS, it is often necessary for EPA to 

balance more reasonable costs against 

the quality or accuracy of the actual 

emissions data collected. 

There are several approaches to Hg 

monitoring that EPA has identified for 

possible use in this rule to determine 

compliance with the proposed Hg 

emission limits. One option is to use a 

CEMS that combines both automated 

sampling and analytical functions in a 

single system to provide continuous, 

real-time Hg emission data. Mercury 

CEMS are currently available from 

several manufacturers. These Hg CEMS 

are similar to most other types of 

instruments used for continuous 

monitoring of pollutants from 

combustion processes, in that the 

combustion gas sample is first extracted 

from the stack and then transferred to an 

analyzer for analysis. In general, the Hg 

CEMS now available can be 

distinguished by the Hg measurement 

detection principle used (e.g., atomic 

adsorption, atomic fluorescence, x-ray 

fluorescence). Capital costs for a Hg 

CEMS are currently estimated to range 

from approximately $95,000 to 

$135,000, depending on the 

manufacturer and model selected. The 

annual costs to operate and maintain a 

Hg CEMS are estimated to range from 

$45,000 to $65,000, again depending on 

the manufacturer and model selected. 

A second option is to use a long-term 

sampling method that collects a 

cumulative Hg sample by continuously 

passing a low-flow sample stream of the 

combustion process flue gas through a 

Hg trapping medium (e.g., an activated 

carbon tube). This sampling tube is then 

periodically removed (e.g., after a day or 

up to 1 month) and replaced with a tube 

filled with fresh trapping medium. The 

removed sampling tube is then sent to 

a laboratory where the trapping medium 

is analyzed for its Hg content. This 

method, like using a Hg CEMS, is 

capable of providing data on the Hg 

emissions from a combustion process on 

a continuous basis, but unlike a Hg 

CEMS, the data are not reported on a 

real-time basis. Using the long-term 

sampling method, the Hg collected in 

the sampling tube is integrated over a 

much longer sampling period (i.e., 1 to 

7 days for the AC tube versus less than 

15 minutes for the CEMS). The capital 

cost for a gas metering system and Hg 

trapping medium is estimated to be 

approximately $18,000. The annual 

costs for periodic sampling tube 

replacement and for the laboratory Hg 

analysis range from approximately 

$65,000 to $125,000 depending upon 

quality assurance and quality control 

(QA/QC) requirements and frequency of 

sample tube replacement.