Clean Air Act Section 110(l) Demonstration 

to Support Amendments to 

COMAR 26.11.27 Emission Limitations for Power Plants 

This is a Clean Air Act section 110(l) demonstration prepared in response to 

the comments received from the United States Environmental Protection 

Agency (EPA) regarding Maryland’s amendment to COMAR 26.11.27 

Emission Limitations for Power Plants. The EPA’s comments were received 

by the Maryland Department of the Environment on May 28, 2009. 

This demonstration shows that the increase in the emissions at R. Paul Smith 

facility will have no impact on Washington County attaining the 1997 

annual PM2.5 standard. 

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Clean Air Act Section 110(l) Demonstration 

to Support Amendments to 

COMAR 26.11.27 Emission Limitations for Power Plants

OVERVIEW

The Maryland Department of the Environment (MDE) has prepared a revision to 

COMAR 26.11.27, Emission Limitations for Power Plants also known as the Healthy Air 

Act (HAA). The emission limits at R. Paul Smith facility for annual and ozone season 

NOX emissions and annual SO2 emissions have been revised. This revision is to abide by 

the exception provision of the Healthy Air Act (HAA) which states: should PJM 

Interconnection, Inc. (PJM Inc.) determine that the termination of operation of the R. 

Paul Smith facility would adversely affect the reliability of electrical services in the PJM 

region then MDE is authorized to allow units 3 and 4 at R. Paul Smith facility to operate 

without complying with the emissions requirements of the HAA. The Healthy Air Act is a 

part of the Washington County PM2.5 SIP. 

Section 110(l) of the Clean Air Act states that the Administrator (of the United States 

Environmental Protection Agency) shall not approve a revision of a plan (State 

Implementation Plan or SIP) if the revision would interfere with any applicable 

requirement concerning attainment or reasonable further progress (of a National Ambient 

Air Quality Standard). To address this anti-backsliding provision, MDE has prepared a 

demonstration that shows that the revision to the emissions limits for R. Paul Smith 

Facility will not interfere with the applicable requirements concerning attainment of the 

National Ambient Air Quality Standards for fine particles. 

BACKGROUND

The Maryland Healthy Air Act was developed with the purpose of bringing Maryland 

into attainment with the National Ambient Air Quality Standards (NAAQS) for ozone 

and fine particulate matter by the federal deadline of 2010. The Healthy Air Act and the 

subsequent regulations also require the reduction of mercury emissions from coal-fired 

electric generating units and significantly reduce atmospheric deposition of nitrogen to 

the Chesapeake Bay and other waters of the State. The HAA regulations became effective 

on July 16, 2007 and require reductions in nitrogen oxide (NOX), sulfur dioxide (SO2), 

and mercury emissions from large coal burning power plants. 

The R. Paul Smith Facility is a 62 year old power plant owned and operated by the 

Allegheny Energy Supply Company, LLC. The facility is located in Washington County, 

Maryland and operates two coal-fired boilers, units 3 and 4. Unit 3’s particulate 

emissions are controlled by a single cold-side electrostatic precipitator (ESP) and NOX

emissions are controlled by low NOX burner technology. Unit 4’s particulate emissions 

are controlled by a primary cold-side ESP and an electrostatically enhanced bag-house 

and NOX emissions are controlled by low NOX burners and a separate over-fire air 

system. 

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The Maryland Department of the Environment recently revised the emissions limitations 

for the R. Paul Smith facility for the reasons outlined in the Healthy Air Act’s exception 

provision (see attached addendum). These amendments were submitted to the U. S. EPA 

for approval as a revision to Maryland’s State Implementation Plan. In accordance with 

the HAA, the guidelines for revising the emissions at R. Paul Smith facility establish that 

should units 3 and 4 be allowed to operate without complying with the emissions 

limitations of the HAA then the following conditions must be met: 

1. The facility may not operate at an emissions level greater than the highest 

level measured at the facility during the calendar years 2000 through 2004 

and; 

2. The Department shall review the operations of the facility and adopt 

regulations to establish an alternative emissions requirement for the 

facility. 

The above mentioned conditions have been met with the revised emission limits for R. 

Paul Smith facility. 

 NOx: 1,390 tons per year; 545 tons per ozone season 

 SO2: 4,590 tons per year 

DEMONSTRATION

In order to support the revision to the emissions limits for R. Paul Smith facility, MDE 

has prepared a demonstration to meet the requirements of Section 110(l) of the Clean Air 

Act. Reasonable Further Progress (RFP) is not required for the PM2.5 SIPs, therefore the 

demonstration will focus on the attainment of the National Air Quality Standards 

(NAAQS). This demonstration is supported by air monitoring data, emissions analysis 

and MANE-VU modeling. 

Air monitoring data shows that Washington County is in attainment of the PM2.5 annual 

and 24-hour standards (see Figures 1 and 2 below). The data from the area’s monitors 

show that the area has been in compliance with the 1997 annual fine particle standard 

since 2000. 

Historically, Washington County has never exceeded the 1996 24-hour design value of 

65μg/m3 (see Figure 2 below). Currently the 24-hour design value for 2006-2008 is 

30μg/m3 approximately 14% below the 2006 24-hour PM2.5 standard of 35μg/m3

. 
Figure 1 - Annual PM2.5 Design Values for Hagerstown, MD from 2002-2006. 

Data from EPA Air Trends Design Values website at: 

http://www.epa.gov/airtrends/values.html. 

Hagerstown, MD Monitor

Annual PM2.5 Design Value (2002-2006)

13.9

14.1 14.1

13.8

14.8

13.2

13.4

13.6

13.8

14

14.2

14.4

14.6

14.8

15

15.2

2000-2002 2001-2003 2002-2004 2003-2005 2004-2006

Design Value (ug/m3) )

Annual PM2.5 Design Value (ug/m3)

Annual PM2.5 Standard (15 ug/m3)

Figure 2 - 24-hour PM2.5 Design Values for Hagerstown, MD from 2001-2006. 

Data from EPA Air Trends Design Values website at: 

http://www.epa.gov/airtrends/values.html. 

Hagerstown, MD Monitor

24-Hour PM2.5 Design Value (2001-2006)

40.0 39.0

36.0

34.0

41.0

30

35

40

45

50

55

60

65

70

2000-2002 2001-2003 2002-2004 2003-2005 2004-2006

Design Value (ug/m3) )

24-Hour PM2.5 Design Value (ug/m3)

24-Hour PM2.5 Standard (65 ug/m3)

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Additionally, it should be noted that Washington County is attaining the PM2.5 standard 

well before the Healthy Air Act provisions take effect in 2009. The annual 2009 design 

value for Washington County is predicted by accepted EPA modeling platforms to range 

between 11.5-11.8 μg/m3

. Original modeling demonstrations for the PM2.5 standard 

were conducted by MANE-VU for the Washington County, MD State Implementation 

Plan. The emissions value used for R. Paul Smith for model year 2009 was 6761.8 tons 

per year of NOX and SO2 combined (see Table 1). The newly proposed emission cap for 

R. Paul Smith (RPS) is 5980 tons per year NOX and SO2 combined (see Table 2). The 

modeled MANE-VU emissions are 11% greater than the proposed emissions limits for 

RPS under the HAA revision. Based on the MANE-VU modeling, the area will attain the 

PM2.5 standard. The revised lower emission limits for R. Paul Smith will not affect the 

county’s attainment of the PM2.5 NAAQS. 

Washington County, Maryland was designated nonattainment for the PM2.5 standard 

primarily because of violations in Berkeley County, West Virginia. Based on the 

modeling performed for the region using the same emissions inventory for R. Paul Smith 

as above, the 2009 design value for Berkeley County, West Virginia is predicted to range 

between 12.8 and 13.1 μg/m3. The revised lower emission limits for R. Paul Smith will 

not affect Berkeley County, West Virginia’s attainment of the PM2.5 NAAQS. 

Table 1 - MANE-VU Projected Emissions R. Paul Smith facility (August 10, 2006) 

Source: MANE-VU

Projected Emissions 

(tons/yr) PLANT_ID POINT_ID PLANT_NAME SCC 

NOX SO2 

043-0005 1 & 2 ALLEGANY ENERGY SUPPLY 

LLC - R. PAUL SMITH 

10100202 

& 

10100212 

1,335 5,426.80

Table 2 - Revised Emissions R. Paul Smith facility (March 2009) 

Revised Emissions 

PLANT_ID POINT_ID PLANT_NAME SCC (tons/yr) 

NOX SO2 

043-0005 1 & 2 ALLEGANY ENERGY SUPPLY 

LLC - R. PAUL SMITH 

10100202 

& 

10100212 

1,390 4,590

The areas attainment of the NAAQS for 8-hour ozone will not be affected by the change 

in the emissions limitations for R. Paul Smith. Washington County’s 8-hour Ozone Early 

Action Compact (EAC) showed attainment of the 1997 8-hour standard by 2007 and 

maintenance through 2012. The HAA is not a part of the Washington County Early 

Action Plan. Therefore the revised emission limits for R. Paul Smith will not affect the 

county’s attainment status under the 8-hour Ozone standard. 

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MDE has made revisions to R. Paul Smith’s allowable emissions limits which fall within 

the range of the guidelines under the Healthy Air Act. These emissions modifications 

were made in accordance with the Healthy Air Act which is a part of the Washington 

County PM2.5 SIP. This 110(l) demonstration illustrates that the revision to the emission 

limits for the R. Paul Smith facility will not interfere with the attainment of the National 

Ambient Air Quality Standards in Washington County. The demonstration is supported 

by modeling results, monitoring data and emissions analysis. Consequently, the revision 

to the emission limits at the R. P. Smith facility cannot be considered backsliding under 

section 110(l) of the Clean Air Act.