# Commonwealth of Pennsylvania



# D ESIGNATION 

# R ECOMMENDATIONS



# F OR THE 

# 20 10 1

- H OUR 

# S ULFUR 

# D IOXIDE



# N ATIONAL 

# A MBIENT 

# A IR 

# Q UALITY 

# S TANDARD



# J UNE 

# 20 11

Bureau of Air Quality

Pennsylvania Department of Environmental Protection

P.O. Box 8468

Harrisburg, PA 17105

- 8468

717

- 787

- 9495

www.depweb.state.pa.usThis page left blank to enable two

- sided copying.

### Designation Recommendations

For the 2010 1

- Hour Sulfur Dioxide

National Ambient Air Quality Standard

Table of Contents

PAGE

Overview of this document

................................ ................................ ................................ . 1

What is SO 2 and why was a new standard necessary?

................................ ........................ 1

What is the process for designating areas and attaining the standard?

............................... 2

What would be the effects of designation as nonattainment?

................................ ......... 4

Designation methodology

................................ ................................ ................................ ... 4

EPA guidance for designation boundaries.

................................ ................................ ..... 4

Designation Recommendations

................................ ................................ .......................... 5

Attainment Areas

................................ ................................ ................................ ............ 5

Nonattainment Areas

................................ ................................ ................................ ...... 6

Unclassifiable Areas

................................ ................................ ................................ ....... 6

Discussion of related factors

................................ ................................ ........................... 8

1. Air quality

................................ ................................ ................................ .............. 8

2. Emissions

................................ ................................ ................................ ............. 10

3. Current level of emission controls

................................ ................................ ....... 12

4. Geography/topography and meteorology

................................ ............................ 15

5. Jurisdictional and other boundaries

................................ ................................ ..... 51

Acronyms and Terms

................................ ................................ ................................ ........ 52

References

................................ ................................ ................................ ......................... 53

APPENDIX A.

Pennsylvania Facilities with Reported SOx Emissions greater than 100 TPY (2007

- 2009)TABLES AND FIGURES

TABLES

Table Title Page

Table 1 Recommended SO 2 Designations in Pennsylvania 7

Table 2 Design Values by Monitor 2008

- 2010 9

Table 3 Pennsylvania SO 2 Emissions

- 2008 11

Table 4 SO 2 Emissions from EGUs 2007

- 2010 13

Table 5 Controls on Electric Generating Units over 100 tons per year of SO 2

Emissions 13

FIGURES

Figure Title Page

Figure 1 Recommended Nonattainment Areas (map) 8

Figure 2 Design Values by Monitor 2008

- 2010 (map) 10

Figure 3 Pennsylvania SO 2 Emissions by County (map) 12

Warren County Analyses

Figure 4 Warren County Topographical Map 16

Figure 5 Warren

- Overlook Monitor Topographical Map 17

Figure 6 Warren

- Overlook Monitor Location 18

Figure 7 Wind Rose f or the Warren

- Overlook Monitor 19

Figure 8 Warren

- Overlook Local Terrain 20

Figure 9 Warren

- Overlook Wind Rose Data for Exceedance Hours 21

Figure 10 Warren

- Overlook Time of Day for SO 2 Exceedances 22

Beaver County Analyses

Figure 11 Beaver County Topographical Map 23

Figure 12 Brighton Township Monitor Topographical Map 24

Figure 13 Brighton Township Monitor Location 25

Figure 14 Wind Rose for the Brighton Township Monitor 26

Figure 15 Brighton Township Monitor Local Terrain 27

Figure 16 Brighton Township Monitor Wind Rose Data for Exceedance Hours 28

Figure 17 Brighton Township Time of Day for SO 2 Exceedances 29

Figure 18 Hookstown Monitor Topographical Map 30

Figure 19 Hookstown Monitor Location 31

Figure 20 Wind Rose for the Hookstown Monitor 32

Figure 21 Hookstown Monitor Local Terrain 33

Figure 22 Hookstown Monitor Wind Rose Data for Exceedance Hours 34

Figure 23 Hookstown Monitor Time of Day for SO 2 Exceedances 35

Allegheny County Analyses

Figure 24 Allegheny County Topographical Map 36

Figure 25 Allegheny County Airport Topographical Map 37

Figure 2 6 Liberty Monitor Topographical Map 38

Figure 2 7 Liberty Monitor Location 39Figure 2 8 Wind Rose for the Liberty Monitor 40

Figure 2 9 Liberty Monitor Local Terrain 41

Figure 30 Liberty Monitor Wind Rose Data for Exceedance Hours 42

Figure 31 Liberty Monitor Time of Day for SO 2 Exceedances 43

Indiana County Analyses

Figure 32 Indiana County Topographical Map 44

Figure 33 Strongstown Monitor Topographical Map 45

Figure 34 Strongstown Monitor Location 46

Figure 35 Wind Rose for the Strongstown Monitor 47

Figure 36 Strongstown Monitor Local Terrain 48

Figure 3 7 Strongstown Monitor Wind Rose Data for Exceedance Hours 49

Figure 3 8 Strongstown Monitor Time of Day for SO 2 Exceedances 50This page left blank to enable two

- sided copying.1



### Overview of this document

The federal Clean Air Act (CAA) provides a mechanism for states to make

recommendations to the United States Environmental Protection Agency (EPA) on the

designation of areas meeting and no t meeting the National Ambient Air Quality

Standards (NAAQS). Section 107(d)(1) of the CAA establishes requirements and

procedures for designating areas as “attainment,” “nonattainment” or “unclassifiable” (if

adequate data is not available) following EPA ’s p romulgation of the NAAQS. 42 U.S.C.

§ 7409(d)(1).

I n June 2010

, EPA revised the NAA QS for sulfur dioxide (SO 2 ) (signed June 2, 2010,

published June 22, 2010 at 75 FR 35,520 ). A new 1

- hour primary standard of 75 parts

per billion (ppb) was established, and the existing 24

- hour and annual primary standards

were revoked. The 1

- hour standard is based on the 3

- year average of the annual 99 th

percentile of 1

- hour daily maximum concentrations.

Following the promulgation of a NAAQS, each s tate submit s NAAQS designation

recommendations to EPA for all areas within its borders one year after the promulgation

of the revised NAAQS; designation recommendations for the SO 2 NAAQS are due to

EPA by June 3 , 2011

. The CAA authorizes the EPA Administrator to modify the

designation recommendations and to provide an opportunity for states to demonstrate

why the proposed modification is not appropriate

.

In this document, the Department of Environmental Protection (DEP or Department) is

making recommendations to EPA on behalf of the Commonwealth of Pennsylvania

concerning the designation of attainment and nonattainment areas in Pennsylvania for the

201 0 SO 2 NAAQS . The designation recommendations are based primarily on air quality

monitoring data for 20 08

- 20 10

. EPA anticipates making initial final designations by

June 2012. The Department will continue to work with EPA during the SO 2 NAAQS

designation process , which is described in more detail below.



### What is SO 2 

### and why was a new standard necessary ?

SO 2 is one of a group of highly reactive gasses known as “oxides of sulfur

. ”

Current scientific evidence links health effects with short

- term exposure to SO 2 ranging

from 5

- minutes to 24

- hours. Adverse respiratory effects include narrowing of the

airways w hich can cause difficulty breathing and increased asthma symptoms. These

effects are particularly important for asthmatics during periods of faster or deeper

breathing (e.g., while exercising or playing). Studies also show an association between

short

- ter m SO 2 exposure and increased visits to emergency departments and hospital

admissions for respiratory illnesses

-- particularly in at

- risk populations including children,

the elderly and asthmatics.2

EPA sets the NAAQS based on its review of existing scient ific knowledge about the

adverse health and welfare effects. The CAA requires EPA to review and update

periodically, if necessary, the NAAQS to “protect public health with an adequate margin

of safety” based on the latest, best

- available science. EPA’s e valuation of the scientific

information and the risks posed by breathing SO 2 indicate that this new 1

- hour standard

will protect public health by reducing people’s exposure to high short

- term (5

- minutes to

24

- hours) concentrations of SO 2

. The revised prim ary standard is consistent with the

advice and recommendations of EPA’s principal independent science advisors on

NAAQS : the Clean Air Scientific Advisory Committee.

EPA estimates that the revised standard will yield health benefits valued between $13

bil lion and $33 billion, including reduced hospital admissions, emergency room visits,

work days lost due to illness, and cases of aggravated asthma and chronic bronchitis,

among other benefits.

Emissions that lead to high concentrations of SO 2 generally als o lead to the formation of

other oxides of sulfur. Reducing SO 2 emissions is expected to have the important co

benefit of reducing the formation of fine sulfate particles that pose significant public

health threats.

EPA also revised the monitoring networ k requirements when it promulgated the 1

- hour

standard. All newly sited SO 2 monitors must be operational by January 1, 2013

. Therefore, EPA will be basing its initial designations upon monitors in operation prior to

2012 and upon any refined air quality modeling completed by the states or EPA.

Nationally, the largest sources of SO 2 emissions are fossil fuel combustion units at power

plants and other industrial facilities. Smaller sources of SO 2 emissions include industrial

processes such as extracting metal from ore, and the burning of high

- sulfur fuels by home

heating equipment, locomotives, large ships, and non

- road equipment.

A ccording to information compiled for 2008 emissions, large statio nary sources

contribute almost 90 percent of the SO 2 emissions in the Commonwealth, with most of

those emissions coming from electric generation units. The latest year for which

emissions for all sectors is available is 2008 . Only large stationary source s are required

to provide emissions information annual ly

.



### What is the process for designating areas and attaining the standard ?

Section 107(d)(1)(B) of the CAA requires EPA to designate areas as nonattainment,

attainment or unclassifiable after promul gating a new NAAQS. 42 U.S.C.

§ 7407(d)(1)(B). Following promulgation of new or revised air standards, G overnors are

required to submit recommendations for attainment

, nonattainment and unclassifiable

areas. G overnors’ recommendations for attainment

, n onattainment and unclassifiable

designations are to be submitted to EPA by June 3 , 2011, one year after the promulgation

of the revised NAAQS. EPA may make modifications and promulgate all or part of a

Governor’s recommendations. If EPA determines that a modification to the3

r ecommendation is necessary, EPA will notify the state no later tha n 120 days prior to

promulgating the designation (120

- day letter) , and must give the state an opportunity to

demonstrate why the potential modification is inappropriate. The CAA requires EPA to

make final designations within two years of promulgation of a NAAQS unless there is

insufficient information, in which case EPA may extend the time period by one year

.

EPA stated in the preamble to the 2010 NAAQS that due to the generally localized

impacts of SO 2 , EPA has not historically considered monitoring alo ne to be an adequate

nor the most appropriate tool to identify all maximum concentrations of SO 2 . Therefore,

EPA expects it will integrate air quality dispersion modeling into all phases of the SO 2 NAAQS implementation. Dispersion modeling uses mathematic al formulations to

characterize the atmospheric processes that disperse a pollutant emitted by a source.

Based on emissions and meteorological inputs , a dispersion model can be used to predict

concentrations at selected downwind receptor locations.

Because of the expected reliance upon dispersion modeling in ultimately determining the

boundaries of designated areas, EPA indicated it would provide additional guidance to

states for designations and plans . However, EPA stated in its preamble to the 201 0

NAAQS that it will take time for EPA to issue th e guidance

, and that it may not be

available for states to use in their initial recommendations

. EPA suggested that initial

state designation recommendations of unclassi fiable would not be unexpected for areas

without violations at an air quality monitor. In its March 24, 2011 memorandum, Area

Designations for the 2010 Revised Primary Sulfur Dioxide National Ambient Air Q uality

Standards , EPA also indicated that even the first round of designations may no t identify

all areas where NAAQS violations may be occurring, and that states would address any

such areas in the course of developing State Implementation Plan (SIP) revisions under

Section 110(a) of the Clean Air Act.

The CAA requires states to submit S ection 110(a) SIP revisions describing how the state

will implement, maintain and enforce the new SO 2 NAAQS. This obligation appl ies to

all areas

, whatever their designation. In the case of SO 2 , the preamble to the NAAQS

promulgation explains the analyti cal framework states are expected to use in submitting

these SIP revisions. To qualify areas as attainment, states are expected to describe how

the standard will be maintained. For designated nonattainment areas, states are required

to submit attainment d emonstration SIP revisions, including implementation of all

reasonably available control measures, incremental reductions showing reasonable

further progress , emission inventories and contingency measures. All SIP revisions are

subject to public review an d comment, including a public hearing.

Designated nonattainment areas are required to attain the standard as expeditiously as

practicable, but no later than five years from the effective date of designation.4

A nticipated milestones for the 1

- hour SO 2 NA AQS are:

June 3 , 2011 State recommendations due to EPA

February 3, 2012 EPA notifies Pennsylvania if EPA intends to modify recommendations for

areas with existing monitoring networks and sufficient data

February 20, 2012 EPA anticipates opening a 30

- day public comment period of intended

designations

April 3, 2012 State deadline for response to EPA notification

June 2012 EPA makes f inal designations for areas based on existing monitoring

network

January 201 3 Additional monitoring to be operational

June 2013 Section 110(a) SIPs due for all areas

February 201 4 Attainment demonstration SIP revision s due to EPA for nonattainment areas

(18 months from the effective date of designation)

Mid

- 2015 Three years of data from new monitors become available to evalua te any

additional monitored violations.

August 201 7 Latest date by which nonattainment areas designated in 2012 must attain the

NAAQS (5 years from the effective date of designations)

What would be the effects of designation as nonattainment?

The CAA contains different requirements for new and modified stationary sources in

areas designated as nonattainment. In addition, the “ general conformity” provisions of

the CAA apply only in nonattainment and maintenance areas ; the requirements of th ese

provisi on s require fe derally

- funded actions and projects must conform to the SIP in order

not to interfere with NAAQS attainment and maintenance. Due to the relatively small

amounts of sulfur in gasoline and on

- road diesel fuel, transportation conformity (which

addresses only highway vehicle emissions) does not apply to the SO 2 NAAQS.



### D esignation m ethodology

EPA guidance for designation boundaries

. Section 107(d)(1) of the CAA defines an area as nonattainment if it does not meet the

NAAQS or if it is contributing to ambient air quality in a nearby area that does not meet

the NAAQS . 42 U.S.C. § 7407(d)(1).

EPA state d in the June 22, 2010 rulemaking that t he expected presumptive boundary for

any area designated nonattainment would be the county boundary associated with a

violation

. States may provide additional information for larger or smaller nonattainment

areas; the additional information would most likely be refined dispersion modeling. In its

March 24, 2011 memorandum, Area Designations for the 2010 Revised Primary Sulfur

Dioxide National Ambient Air Q uality Standards , EPA also recommended defining

nonattainment boundaries with the use of well

- defined jurisdictional lines or immovable

landmarks or other readily identifi able boundaries.5

EPA did not identify other specific factors in the preamble to the June 22, 2010

rulemaking that states should consider in their designation recommendations, but it did so

in its March 24, 2011, memorandum. Because 1

- hour SO 2 violations are generally

associated with a large specific source (usually a stationary source), not all of the factors

associated with regional pollutants such as ozone or fine particulates are appropriate

considerations for this pollutant , such as population growth

. EPA is recommending states

base boundary recommendations on five factors, and other available data:

1. air quality data

2. emissions

- related data

3. meteorology

4. geography and topography

5. jurisdictional and other boundaries

The Department has not yet conducted dispersion modeling for its SO 2 sources to be used

in informi ng designation recommendations, because EPA guidance was not issued in

sufficient time. The Department will conduct dispersion modeling in accordance with

EPA guidance for many of its SO 2 sources to be able to respond to EPA before EPA

makes its final designations in June 2012, including responding to the notice EPA must

provide 120 days before the final designations if EPA intends to modify our

recommended designations . Modeling will ena ble the Department to better consider the

five factors recommended by EPA for boundary recommendations. The Department will

aim to fulfill its obligations to submit Section 110(a) SIP revisions by June 2013 and

submit attainment demonstrations in February 2014.



### Designation Recommendations

The Department has determined that the EPA presumptive county boundary approach is

reasonable for Pennsylvania

.

EPA stated in the preamble to the 1

- hour SO 2 NAAQS rulemaking that

, for these initial

designation recommendations, states should use monitoring data from the existing SO 2 network for the years 2008

- 2010. The Department and the local air quality agencies in

Philadelphia and Allegheny counties operated 2 8 monitors in 20 co unties during the

period 2008

- 2010. Two of the monitors are special purpose monitors which do not meet

the required network design criteria for the SO 2 NAAQS. The Department will provide

EPA with any updated information available (for example, monitoring data for 2011 and

a design value for 2009

- 2011) in response to EPA’s 120

- day letter expected in February

2012.

Attainment Areas

Of the 2 6 network monitors, 2 1 monitors in 16 counties did not show violations of the 1

-

hour SO 2 standard (including 3 monitors where data is incomplete). EPA stated in the

preamble to the NAAQS rulemaking that absent monitoring data and air quality modeling

results showing no violations, it expects that the initial designations will be unclassifiable

as required by the Clean Air Act. Since the Department has not completed any dispersion6

modeling for designation purposes

, no areas are being recommended as attainment at this

time. If Department

- conducted or evaluated dispersion modeling for sources in these

counties can demonstrate attainment of the 1

- hour standard , the Department will revise

its recommend ations from u nclassifiable to attainment.

Nonattainment Areas

Monitors in Allegheny, Beaver, Indiana and Warren counties are violating the 1

- hour SO 2 NAAQS using monito ring data from 2008

- 2010. The Department is recommending that

these counties be designated as nonattainment areas

.

In addition, Section 107(d)(1)(C)(i) of CAA , regarding designations by operation of law,

provides that an area designated as nonattainment with respect to any air pollutant before

November 1990 is designated as a nonattainment area for that pollutant. Portions of

Armstrong County (Madison, Mahonin g, Boggs, Washington and Pine townships) are

designated as nonattainment for the 3

- hour and annual SO 2 NAAQS. T herefore, the

Department expects EPA to include these townships in its designations as nonattainment

for the 1

- hour SO 2 standard.

Unclassifiab le Areas

At this time, t he Department is recommending that all other counties in Pennsylvania be

designated as unclassifiable.

The Department will be conducting or evaluating refined air quality d ispersion m odeling

for sources. However, in Pennsylvania, there are more than 100 facilities with SO 2

emissions more than 100 tons per year (tpy) (determined by the maximum annual

emissions in 2007, 2008 or 2009) and as many as 1

, 300 facilities with any reported SO 2 emissions. Modeling for these sources will be an enormous and resource intensive

undertaking

. EPA guidance was not provided in sufficient time to ensure modeling for a

June 2011, submission of recommendations conform ing to the guidance.

The Department may revise its recommendations regarding unclass ifiable areas to

recommend that designat ions be revised to either nonattainment or attainment based upon

that modeling. There is little doubt that there are modeled violations in the

Commonwealth associated with large sources of SO 2 emissions outside thos e counties

with violating monitors

. For example, o f the five facilities with 2007

- 200 9 maximum

annual emissions of 100,000 tpy or greater, only one is in a county that is monitoring

nonattainment.

Dispersion modeling to support the Department’s 1

- hour SO 2 designation

recommendations will follow the United States Environmental Protection Agency

(USEPA) March 24, 2011 memorandum, Area Designations for the 2010 Revised

Primary Sulfur Dioxide National Ambient Air Q uality Standards

. The Department

intends to make available to the public the results of any modeling that has been

completed by February 2012 . EPA has indicated it would also provide an opportunity for

public comment at that time o f its intended designations and responses to state

recommendations

.7

Table 1 summarizes the Commonwealth’s recom mendations by county. Figure 1 is a

map showing the recommended nonattainment areas.

Table 1

. Recommended SO 2 Designations in Pennsylvania

PA Counties Recommendation PA Counties Recommendation

Adams County Unclassifiable Lackawanna County Unclassifiable

Allegheny County Nonattainment Lancaster County Unclassifiable

Armstrong County Unclassifiable Lawrence County Unclassifiable

Beaver County Nonattainment Lebanon County Unclassifiable

Bedford County Unclassifiable Lehigh County Unclassifiable

Berks County Unclassifiable Luzerne County Unclassifiable

Blair County Unclassifiable Lycoming County Unclassifiable

Bradford County Unclassifiable McKean County Unclassifiable

Bucks County Unclassifiable Mercer County Unclassifiable

Butler County Unclassifiable Mifflin County Unclassifiable

Cambria County Unclassifiable Monroe County Unclassifiable

Cameron County Unclassifiable Montgomery County Unclassifiable

Carbon County Unclassifiable Montour County Unclassifiable

Centre County Unclassifiable Northampton County Unclassifiable

Chester County Unclassifiable Northumberland County Unclassifiable

Clarion County Unclassifiable Perry County Unclassifiable

Clearfield County Unclassifiable Philadelphia County Unclassifiable

Clinton County Unclassifiable Pike County Unclassifiable

Columbia County Unclassifiable Potter County Unclassifiable

Crawford County Unclassifiable Schuylkill County Unclassifiable

Cumberland County Unclassifiable Snyder County Unclassifiable

Dauphin County Unclassifiable Somerset County Unclassifiable

Delaware County Unclassifiable Sullivan County Unclassifiable

Elk County Unclassifiable Susquehanna County Unclassifiable

Erie County Unclassifiable Tioga County Unclassifiable

Fayette County Unclassifiable Union County Unclassifiable

Forest County Unclassifiable Venango County Unclassifiable

Franklin County Unclassifiable Warren County Nonattainment

Fulton County Unclassifiable Washington County Unclassifiable

Greene County Unclassifiable Wayne County Unclassifiable

Huntingdon County Unclassifiable Westmoreland County Unclassifiable

Indiana County Nonattainment Wyoming County Unclassifiable

Jefferson County Unclassifiable York County Unclassifiable

Juniata County Unclassifiable8 Figure 1. Recommended Nonattainment Areas.

Discussion of related factors

A general discussion of each factor and sources of information relevant to SO 2 designations is provided in this section of the document . The Department is using this

information in prioritizing and conducting its modeling for purposes of working with

EPA on designations during the designat ion process.

1. Air quality

The Department ’s designation recommendations for the short

- term SO 2 NAAQS are

based on the 20 10 SO 2 design values 1 ( calculated using the 200 8 , 200 9 , and 20 10

monitored data).

1 The design value for the 1

- hour SO 2 standard i s based on the 3

- year average of the annual 99 th percentile

of 1

- hour daily maximum concentrations.9 Table 2

. Design Values by Monitor (2008

- 2010)

County Site 1

- hour Design

Value (ppb)

Allegheny Co. Avalon 63

Allegheny Co. Liberty 128

Allegheny Co. Pittsburgh (BAPC) 29*

Allegheny Co. Pittsburgh (Carnegie

- DEP) special purpose

Allegheny Co. South Fayette 48

Allegheny Co. Stowe 66

Beaver Co. Brighton Twp 167

Beaver Co. Hookstown 101

Berks Co. Reading Airport 43

Blair Co. Altoona 47

Bucks Co. Bristol 27

Cambria Co. Johnstown 66

Centre Co. State College 29

Delaware Co. Chester 38

Erie Co. Erie 34

Greene Co. Holbrook special purpose

Indiana Co. Strongstown 90

Lawrence Co. New Castle 65

Luzerne Wilkes

- Barre 26

Montgomery Co. Norristown 23

Northampton Co. Easton 50

Perry Co. Perry County 30

Philadelphia Co. AMS 29*

Philadelphia Co. Ritner 29*

Warren Co. Warren Overlook 123

Washington Co. Charleroi 67

Washington Co. Florence 60

York Co. York 71

(* does not meet data completeness requirement)10 Figure 2. Design Values by Monitor (2008

- 2010)

The DEP’s Ambient Air Monitoring Network Plan

– 201 1 (June 25, 2010), the

Philadelphia Air Management Services’ (AMS) 20 10 /201 1 Air Monitoring Network Plan

(July 1, 20 10 ) and the Allegheny County Health Department’s (ACHD) “Monitoring

Network Review” ( July 1, 2010 ) describe the Commonwealth’s plans for additional SO 2 monitoring. These documents are available on each of the respective agencies’ websites

as listed in the referen ce section. However, since these monitors will not have three years

of data by the time EPA makes its initial designations, the SO 2 designation

recommendations are based only upon the existing network

.

2. Emissions

The counties that the Department is recommending as SO 2 nonattainment areas contain

the following number of large sources (over 100 tpy of SO 2 in 2007, 2008 or 2009) of

SO 2 :

Allegheny County : 7 facilities

Beaver County : 3 facilities

Indiana County : 3 f

acilities

Warren County : 1 facility11

A list of sources emitting over 100 tpy of SO 2 (maximum 2007

- 2009 reported emissions

data) sorted by county is provided in Appendix A.

EPA expects active s tationary sources to be the primary contributor s to violations of the

1

- hour SO 2 NAAQS. Note that these sources are not the only sources of SO 2 emissions.

For example, t he combustion of coal and oil for heating and industrial

, commercia l, or

institutional purposes and the combustion of diesel for tran sportation purposes also

contribute to SO 2 emissions.

The Department prepares an emission inventory for all criteria pollutants from all sectors

every three years. Only stationary source data is available every year; t he most recent

full inventory was for the year 2008.

Table 3. Pennsylvania SO2 Emissions

– 2008

SECTOR Emissions

Tons per Year Emissions

Percent

Stationary 864

, 732 87.0%

Electric Generating Unit (EGU)

Non

- EGU 819,015

45,717 (% of stationary)

94.7%

5.3%

Area stationary (includes small

sources and home heating) 125

, 85 5 12.7%

Highway 1

, 661 0.2%

Nonroad 2, 18 3 0.2%

TOTAL 994,43012 Figure 3. Pennsylvania SO 2 Emissions By County (2008)

3. Current level of emission controls

As indicated above, EGUs contribute about 82 percent of the SO 2 emissions in

Pennsylvania. The EPA has included 40 EGUs operating in the Commonwealth in its

National Electric Energy Data System (NEEDS). NEEDS 4.10 is the database of existing

and planned

- committed units which are in the EPA Base Ca se for the Integrated Planning

Model (IPM) runs for the proposed Transport Rule (August 2, 2010). IPM is a multi

regional, dynamic, deterministic linear programming model of the U.S. electric power

sector.

The Clean Air Interstate Rule and acid rain prog rams have caused significant reductions

to be made in Pennsylvania in SO 2 emissions from sources affected by those programs in

recent years.13 Table 4. SO 2 Emissions from EGUs

(Source: EPA Acid Rain Program)

YEAR SO2 (Tons)

2007 951,186.1

2008 831,914.9

2009 573,618.7

2010 393,196.4

Table 5 identifies EGUs in Pennsylvania and existing SO 2 controls.

Table 5. Controls on Electric Generating Units over 100 tons per year of SO 2 Emissions (Max 2007

- 2009)

( S ource: EPA National Electric Energy Data System v 410 )

FACILITY FIRING COUNTY CONTROL

Cheswick Coal Steam Allegheny Wet Scrubber

Keystone Coal Steam Armstrong Wet Scrubber

Armstrong Power Station Coal Steam Armstrong

Bruce Mansfield Coal Steam Beaver Wet Scrubber

AES Beaver Valley Partners

Beaver Valley Coal Steam Beaver Wet Scrubber

Titus Coal Steam Berks

Wheelabrator Falls Munic solid

waste Bucks Dry Scrubber

Colver Power Project Coal Steam Cambria Reagent Injection

Ebensburg Power Coal Steam Cambria Reagent Injection

Cambria Cogen Coal Steam Cambria Reagent Injection

Panther Creek Energy

Facility Coal Steam Carbon Reagent Injection

Cromby Generating Station Coal Steam Chester Wet Scrubber

Cromby Generating Station O/G Steam Chester

Piney Creek Project Coal Steam Clarion Reagent Injection

Shawville Coal Steam Clearfield

Eddystone Generating

Station Coal Steam Delaware Wet Scrubber

Eddystone Generating

Station O/G Steam Delaware

Eddystone Generating

Station O/G Steam Delaware

Hatfields Ferry Power Station Coal Steam Greene Wet Scrubber

Conemaugh Coal Steam Indiana Wet Scrubber

Homer City Station Coal Steam Indiana Wet Scrubber on 1 of 3 coal

sources

Seward Coal Steam Indiana Dry Scrubber

New Castle Coal Steam Lawrence

PPL Montour Coal Steam Montour Wet Scrubber14

Table 5. Controls on EGUs continued

FACILITY FIRING COUNTY CONTROL

Portland Coal Steam Northampton

Northampton Generating

Company Coal Steam Northampton Reagent Injection

PPL Martins Creek O/G Steam Northampton Shutdown*

Foster Wheeler Mt Carmel

Cogen Coal Steam Northumberland Dry Scrubber

John B Rich Memorial Power

Station Coal Steam Schuylkill Reagent Injection

WPS Westwood Generation

LLC Coal Steam Schuylkill Reagent Injection

Wheelabrator Frackville

Energy Coal Steam Schuylkill Reagent Injection

St Nicholas Cogen Project Coal Steam Schuylkill Reagent Injection

Sunbury Generation LP Coal Steam Snyder Wet Scrubber on 4 coal sources

Sunbury Generation LP Coal Steam Snyder Reagent Injection on 2 coal

sources

Scrubgrass Generating Coal Steam Venango Reagent Injection

Elrama Coal Steam Washington Wet Scrubber

Mitchell Power Station Coal Steam Washington Wet Scrubber

Mitchell Power Station O/G Steam Washington

PPL Brunner Island Coal Steam York Wet Scrubber

P H Glatfelter Coal Steam York Reagent Injection on 1 of 4

sources

*Included in EPA's database for analysis purposes

SO 2 controls can include wet or dry scrubbers , a lso known as flue gas desulfurization

(FGD) systems . SO 2 scrubbers use chemical and physical absorption to remove SO 2 from the flue gas. Wet scrubbers use a liquid sorbent to remove SO 2 and the flue gas

leaving the absorber is moisture saturated. With dry scrubbers the flue gas leaving the

absorber is not sat urated. For circulating fluidized bed units (as shown in the "Firing"

field), this field indicates whether reagent injection is used for SO 2 control. Reagent

injection involves adding finely crushed limestone to the fluidized bed. During

combustion, the limestone is reduced to lime, the sulfur in the fuel is oxidized to form

SO 2 , and, in the presence of excess oxygen, the SO 2 reacts with the lime particles to form

calcium sulfate, which can be removed with the bottom ash or collected with the fly ash

by a downstream particulate matter control device.

Existence of SO 2 controls does not necessarily equate to modeled attainment of the 1

-

hour SO 2 standard. EPA guidance recommend s that dispersion modeling for designation

purposes “should be based on the use of maximum allowable emissions or federally

enforceable permit limits.”

The Commonwealth has also proposed lower sulfur limits for commercial fuel oil, both

for heating and indust rial/commercial purposes

. Finally, EPA has issued rules to reduce

sulfur in fuel used in large commercial marine vessels (directly affecting the ports of

Erie, Pittsburgh and Philadelphia, but with significant ambient air effects much farther15

inland). Be ginning in 2015, fuel used by all vessels operating in these areas cannot

exceed 0.1 percent fuel sulfur (1,000 ppm). This requirement is expected to reduc e SO 2 emissions by more than 85 percent.

4. Geography/topography and meteorology

Local terrain an d meteorology affect the direction of transport and the dispersion of

pollutants. The recommended model for SO 2 modeling, AERMOD, contains modules

that account for terrain and meteorology. Meteorological data must be spatially and

climatologically (tempo rally) representative of the area of interest. The

representativeness of the data is dependent on: (1) t he proximity of the meteorological

monitoring site to the area under consideration; (2) the complexity of the terrain; (3) the

exposure of the meteoro logical monitoring site; and (4) the period of time during which

data are collected. Because most of the largest SO 2 sources have been through relatively

recent plan approval processes that required air quality modeling, the Department

believes that it ha s representative meteorological data in

- house for its modeling efforts

related to designations.

Air quality impact analysis must also consider how terrain features influence the behavior

of air pollution plumes. AERMOD uses a terrain preprocessor to generate elevation data

for each model receptor. It also provides information that allows the dispersion model to

simulate the effects of air flowing over hills or splitting to flow around hills.

The Dep artment has conducted initial meteorological and topographic analys e s for the

monitors in the four recommended nonattainment areas. The analysis confirms that the

county nonattainment area is the most reasonable boundary for Warren, Beaver and

Allegheny counties, because the source s of the violations are most likely within the

county. For Indiana County, the analysis indicated that, while a county boundary is

reasonable, further analysis through modeling may be necessary to assess whether the

nonattainme nt boundaries should be refined. Overall, the prominent w esterly winds and

strong er wind speeds are indicating that the driving source of the higher SO 2

concentrations may be coming from the larger SO 2 sources to the west of Strongstown.

These types of s ources generally have taller stacks and higher emission rates which helps

in the downwind transport of pollution. Until this analysis is completed, the Department

is recommending a county nonattainment boundary for Indiana County.

Warren County

Warren County is situated within the western flank of the Appalachian Mountain chain.

Figure 4 below displays a topographical overview of all of Warren County. There is one

major river that runs through the county. The Allegheny River flows from the Allegheny

Reservior (in the far northeastern portion of the county, south and eastward toward Forest

County on its way into Pittsburgh. Otherwise, the county is marked by its higher terrain.

When combined with the Allegheny River, this higher terrain is what helps drive the

meteorological pattern within the county.16 Figure 4

. Warren County Topographical Map17

Warren

- Overlook SO 2 Monitoring Location

Warren

- Overlook is situated on a portion of the higher terrain in the eastern side of

Warren County. Figure 5 displays the location of the Warren

- Overlook monitor with

respect to the major SO 2 sources. In addition, Figure 2 highlights the terrain above the

anemometer of height o f the Warren

- Overlook meteorological tower (anemometer is at

10 meters plus base elev ation of tower at 580 meters). Therefore, the measurements

being taken by the Warren

- Overlook meteorological tower are likely to be influenced by

t he higher terrain to its east

.

Figure 5

. Warren

- Overlook Topographical Map18

Figure 6 (courtesy of Go ogle Earth) displays a zoomed in look at the actual Warren

Overlook monitoring location with respect to the other regional SO 2 sources.

Figure 6 . Warren Overlook Monitoring Location19

The impact of the topography near Warren

- Overlook can also be seen by looking at the

wind measurements that were collected at the Warren

- Overlook air monitoring station

(meteorological data, including wind direction and speed, are continuously measured).

Figure 7 (courtesy of Google Earth) displays the wind data measured at Warren

Overlook’s meteorological tower from January 2008 to December 2010 (a full three year

dataset).

Figure 7 . Wind Rose for the Warren

- Overlook Monitor

T he wind is primarily out of the west and south west. There is also a secondary maximum

out of the north and east. This wind profile follows the synoptic wind flow over northern

Pennsylvania. Stronger winds exist out of the southwest than out of the northeast

because the win ds out of the southwest are undergoing less friction (the main river that

runs through Warren County runs off to the south of the monitoring station)

. The wind

undergoes more friction from the northeast due to the higher terrain in that direction.20

Ta king a cross section look (in three dimensions within Google Eart h) at the local area in

Figure 8 below, one can see the relationship of the local terrain with respect to the major

SO 2 sources in the region and the Warren

- Overlook air monitor station.

Figure 8 . Local Terrain

From Figure 8 (which looks south to north), one can see that the Warren

- Overlook air

monitoring station sits on the side of a hill . The main SO2 source in the region sits down

within the river valley.

Also from Figure 8 above , one can see that the Warren

- Overlook monitor lies to the west

of th e major SO 2 source. The Warren

- Overlook monitor acquires SO 2 samples from the

air continuously every hour, which results in approximately 8760 hours of samples every

year. The latest de sign value year, 2010 (which is based on data from 2008 to 2010),

showed the Warren

- Overlook monitor exceeding the new SO 2 standard with a

concentration of 123 ppb. The Department analyzed the data to focus in on the hour s in

which the SO 2 concentrations exceeded the new 1

- hour SO 2 standard. 1 12 hours were

found to exceed this threshold. Out of those 1 12 hours, 88 hours had complete

corresponding meteorological data. Then, the Department analyzed the wind data and

created a wind rose to coincide with the meteorological data collected on those 88 hours

that were found to exceed the new 1

- hour SO 2 standard threshold.21

Figure 9 shows the results.

Figure 9 . Wind Rose Data for Exceedance Hours

W hen com paring this figure with Figure 7 above, one will notice that the primary wind

direction has changed. During the periods when there are high SO 2 concentrations, the

wind is primarily out of the north and east . In addition, wind speeds are generally

strong er, out of the east, indicating that the winds are unimpeded (from the impact of

higher terrain) from that direction. Rotating counter

- clockwise, the winds become

generally lighter as the winds undergo more friction (from the higher terrain to the north).

The combination of the severe terrain within the Warren

- Overlook area combined with

northeasterly component of the wind would indicate that a local source within the valley

is creating the high SO 2 concentrations

.22

The time of the day when the SO 2 concentrations are occurring is a lso of importance.

Figure 10 illustrates when the Warren

- Overlook monitor is experiencing the high 1

- hour

SO 2 concentrations.

Figure 10 . Time of Day for SO 2 Exceedamces

All of the high SO 2 concentrations are occurring in the late evening to early mo rning

hours (from 7 PM to 9 AM). The timing of these exceedances coupled with the fact that

the Warren

- Overlook monitoring site is situated within a valley increases the likelihood

that meteorological inversions are assisting in driving SO 2 concentrations higher. Once

an inversion forms and the wind near the surface decreases

, localized air pollution

becomes trapped near the surface. Therefore, there is even more likelihood that the high

SO 2 concentrations are driven by an SO 2 source in close proximity t o monitor.

Due to the nature of the high SO 2 concentrations around the Warren

- Overlook monitor,

the Departmen t is recommending that Warren County be designate d nonattainment for

the new SO 2 standard

.

Beaver County

Beaver County is situated to the west of the Appalachian Mountain ch ain. Figure 1 1

below displays a topographical overview of all of Beaver County. There are two major

rivers that run through the relatively high terrain of Beaver County. The Ohio River,

which flows into the county from Pittsburgh, runs from east to west across the county.

The Beaver River

, flows from south to north from Lawrence County into the Ohio River23

near the city of Monaca. When combined with the higher topography, these rivers help

drive th e meteorological pattern witnessed within the county.

Figure 11

. Beaver County Topographical Map24

Brighton Township SO 2 Monitoring Location

Brighton Township is situated on higher terrain while being within a mile of the Ohio

River (which lies to the south of the monitor). Figure 1 2 displays the location of the

Brighton Township monitor with respect to the major SO 2 sources. In addition, Figure 2

highlights the terrain above the anemometer of height o f the Brighton Township

meteor ological tower (anemometer is at 10 meters plus base elevation of tower at 366

meters). Therefore, the measurements being taken by the Brighton Township

meteorological tower are not very influenced by any of the terrain in its immediate

vicinity.

Figure 1 2

. Brighton Township (Beaver County) Topographical Map25

Figure 1 3 (courtesy of Google Earth) displays a zoomed in look at the actual Brighton

Township monitoring location with respect to the other regional SO 2 sources.

Figure 1 3 . Brighton Townshi p Monitoring Location26

The impact of the topography near Brighton Township can also be seen by looking at the

wind measurements that were collected at the Brighton Township air monitoring station

(meteorological data, including wind direction and speed, are continuously measured ).

Figure 1 4 (courtesy of Google Earth) displays the wind data measured at Brighton

Township’s meteorological tower from January 2008 to December 2010 (a full three year

dataset).

Figure 1 4 . Wind Rose Data for the Brighton Monitor

T he wind is prim arily out of the west and northwest. This wind profile follows the

synoptic wind flow over the region and is not surprising by referencing Figure 1 2 above,

which shows that there is not any significant terrain that is influencing the wind

measurements.27

Taking a cross section look (in three dimensions within Google Earth) at the local area in

Figure 1 5 below, one can see the relationship of the local terrain with respect to the major

SO 2 sources in the region and the Brighton Township air monitor stati on.

Figure 1 5 . Local Terrain

From Figure 1 5 (which looks south to north), once again one can see that the Brighton

Township air monitoring station sits on top of a local hill, with many of the major SO 2 sources sitting in the Ohio River valley.

Also from Figure 1 5 above, one can see that the Brighton Township monitor lies to the

north of these SO 2 sources. The Brighton Township monitor acquires SO 2 samples from

the air continuously every hour, which results in approximately 8760 hours of samples

every year. The latest design value year, 2010 (which is based on data from 2008 to

2010), showed the Brighton Township monitor exceeding the new SO 2 standard with a

concentration of 167 ppb. The Department analyzed the data to focus in on the hour s in

which the SO 2 concentrations exceeded the new 1

- hour SO 2 standard. 183 hours were

found to exceed this threshold. Out of those 183 hours, 110 hours had complete

corresponding meteorological data. Then, the Department analyzed the wind data and

created a wind rose to coincide with the meteorological data collected on those 110 hours

that were found to exceed the new 1

- hour SO 2 standard threshold.28

Figure 1 6 shows the results.

Figure 1 6

. Wind Rose Data for Exceedance Hours

W hen comparing this figure with Figure 1 4 above, one will notice that the primary wind

direction has changed. During the periods when there are high concentrations of SO 2 , the

wind is primarily out of the s outh, southwest. In addition, wind speeds are gen erally

slower, indicating that a much more stable air mass is in place over the region when SO 2 concentrations rise. A stable boundary layer would limit vertical mixing, thus allowing

concentrations to build near the surface. Overall, the prominent south westerly winds and

lighter wind speeds are indicating that the driving source of the higher SO 2 concentrations

is coming from the SO 2 sources sitting within the Ohio River valley to the monitors

south.29

The time of the day when the SO 2 concentrations ar e occurring is also of importance.

Figure 1 7 illustrates when the Brighton Township monitor is experiencing the high 1

-

hour SO 2 concentrations.

Figure 1 7 . Time of Day For SO 2 Exceedances

Most of the high SO 2 concentrations are occurring in the late evening to early morning

hours (from 8 PM to 10 AM). The timing of these exceedances coupled with the fact that

the Brighton Township monitoring site is situated within a valley increases the likelihood

that meteo rological inversions are assisting in driving SO 2 concentrations higher. Once

an inversion forms and the wind near the surface decreases (see Figure 6 for an example

of this), localized air pollution becomes trapped near the surface. Therefore, there is even

more likelihood that the high SO 2 concentrations are driven by an SO 2 source in close

proximity to monitor.

Hookstown SO 2 Monitoring Location

Hookstown is situated on higher terrain while being within several miles of the Ohio

River (which lies to the north of the monitor). Figure 1 8 displays the location of the

Brighton Township monitor with respect to the major SO 2 sources. In addition, Figure 1 8

highlights the terrain above the anemometer height of the Hookstown meteorological

tower (anemometer is at 10 meters plus base elevation of tower at 366 meters).

Therefore, the measurements being taken by the Hookstown meteorological tower are not

very influenced by any of the terrain in its immediate vicinity.30 Figure 1 8

. Hookstown (Beaver County) Topographical Map31

Figure 1 9 (courtesy of Google Earth) displays a zoomed in look at the actual Hookstown

monitoring location with respect to the other regional SO 2 sources.

Figure 1 9 . Hookstown Monitor Location Map32

The impact of the topography near Hookstown can also be seen by looking at the wind

measurements that were collected at the Hookstown air monitoring station

(meteorological data, including wind direction and speed, are continuously measured).

Figure 2 0 (courtesy of Google Earth) displays the wind data measured at Brighton

Township’s meteorological tower from January 2008 to December 2010 (a full three year

dataset).

Figure 2 0 . Wind Rose for the Hookstown Monitor

T he wind is primarily out of the west and south west. This wind profile follows the

synoptic wind flow over the region and is n ot surprising by seeing Figure 1 8 above,

which shows that there is not any significant terrain that is influencing the wind

measur ements.33

Taking a cross section look (in three dimensions within Google Eart h) at the local area in

Figure 2 1 below, one can see the relationship of the local terrain with respect to the major

SO 2 sources in the region and the Hookstown air monitor sta tion.

Figure 2 1 . Local Terrain

From Figure 2 1 (which looks south to north), once again one can see that the Hookstown

air monitoring station sits on top of a local hill, with the closest SO 2 source in

Pennsylvania sitting in the Ohio River valley off to the north and east of the Hookstown

monitor

.

Also from Figure 2 1 above, one can see that the Hookstown monitor lies to the southwest

of th is SO 2 source. The Hookstown monitor acquires SO 2 samples from the air

con tinuously every hour, which results in approximately 8760 hours of samples every

year. The latest design value year, 2010 (which is based on data from 2008 to 2010),

showed the Brighton monitor exceeding the new SO 2 standard with a concentration of

101 pp b. The Department analyzed the data to focus in on the hour s in which the SO 2

concentrations exceeded the new 1

- hour SO 2 standard. 74 hours were found to exceed

this threshold. Out of those 74 hour s, 74 hours had complete corresponding

meteorological da ta. Then, the Department analyzed the wind data and created a wind

rose to coincide with the meteorological data collected on those 74 hours that were found

to exceed the new 1

- hour SO 2 standard threshold.34

Figure 2 2 shows the results.

Figure 2 2

. Wind Rose Data for Exceedance Hours

W hen com paring this figure with Figure 2 0 above, one will notice that the primary wind

direction has changed. During the periods when there are high SO 2 concentrations, the

wind is primarily out of the west . In addition, wind speeds are generally strong er,

indicating that the high SO 2 concentrations are being driven in from out of state

. Comparing the strong westerly component of the winds with the fact that there are no

other major SO 2 emissions sources w ithin Pennsylvania in close proximity of the

Hookstown monitor indicates that the Hookstown monitor is picking up on the intrastate

transport of SO 2 . Overall, the prominent w esterly winds and strong er wind speeds are

indicating that the driving source of the higher SO 2 concentrations is coming from the

SO 2 sources cited in states to our west

.35

The time of the day when the SO 2 concentrations are occurring is also of importance.

Figure 2 3 illustrates when the Hookstown monitor is experiencing the high 1

- h our SO 2

concentrations.

Figure 2 3 . Time of Day for SO 2 Exceedances

Most of the high SO 2 concentrations are occurring in the middle of the day hours (from 9

AM to 5 PM). The timing of these exceedances coupled with the fact that the Hookstown

monitoring site is situated on higher terrain increases the likelihood that intrastate

transport is playing a role in the monitored SO 2 concentration exceedances. The middle

of the day is when the atmosphere is the most unstable, meaning that more horizo ntal and

vertical mixing is occurring. The onset of this mixing usually occurs in the late morning

when, after a cool night, the sun warms the surface. The air at the surface is then warmer

and less dense than its surroundings so it wants to rise, induci ng vertical motion. The top

two hours when we see the most exceedances are 10 and 11 AM, when vertical mixing

begins. Therefore, there is even more likelihood that the high SO 2 concentrations are

driven by SO 2 sources by SO 2 sources to the west of the Ho okstown monitor.

Due to the nature of the high SO 2 concentrations around the Brighton Township and

Hookstown monitors, the Department is recommending that Beaver County be

designated nonattainment for the new SO 2 standard

.36

Allegheny County

Allegheny County is situated to the west of the Appalachian Mountain chain. Figure 24

below displays a topographical overview of all of Allegheny County. There are four

major rivers that run through the relatively high terrain of Allegheny County. The

Monongahel a River, which runs from the Washington County line northward, and the

Allegheny River, which runs from the Westmoreland County line southward, converges

in Pittsburgh to form the Ohio River, which runs from Pittsburgh northwestward toward

Beaver County. The Youghiogheny River, in southeastern Allegheny County, flows into

the Monongahela River. When combined with the higher topography, these rivers help

drive the meteorological pattern witnessed within the county.

Figure 24. Allegheny County Topographical Map37

Liberty SO 2 Monitoring Location

Liberty is situated on higher terrain while being surrounded by two rivers: the

Youghiogheny River to the east and the Monongahela River to the west. Figure 25

displays the location of the Liberty monitor with respect to the major SO 2 sources In

addition, Figure 2 highlights the terrain above the anemometer of height o f the Allegheny

County Airport meteorological tower (anemometer is at 1 0 meters plus base elevation of

tower at 380 meters). The measurements being taken by the Allegheny County Airport

meteorological tower are likely to not be influenced by any higher terrain.

Figure 25. Allegheny County Airport Topographical Map38

T he Liberty air monitoring station also collected meteorological data during the three

year period (Jaunary 2008 to December 2010). However, the meteorological data set

during that time frame was not complete, which is why the Allegheny County Airport’s

me teorological data was utilized. Figure 26 highlights the terrain above the anemometer

of height o f the Liberty monitoring station (anemometer plus base elevation of tower at

380 meters). If available, the measurements being taken by the Liberty meteorolo gical

tower are likely to be influenced by the local te rrain.

Figure 26. Liberty Monitor Topographical Map

The difference in elevation between the Allegheny County Airport and the Liberty air

monitoring stations is approximately 55 meters.39

Figure 27 (courtesy of Google Earth) displays a zoomed in look at the actual Liberty

monitoring location with respect to the other regional SO 2 sources.

Figure 27. Liberty Monitor Location Map40

The impact of the topography near Liberty can also be seen by looking at the wind

measurements that were collected at the Allegheny County Airport meteorological tower.

Figure 28 (courtesy of Google Earth) displays the wind data measured at the Allegheny

County Airport’s meteorological tower from January 2008 to December 2010 (a full three

year dataset).

Figure 28. Wind Rose for the Allegheny County Airport

T he wind is primarily out of the west and south

. There is also a secondary maximum out

of the north. This wind profile follows the synoptic wind flow over southwestern

Pennsylvania. Stronger winds exist at this monitoring station because the wind is not

undergoing any friction because it is not impacted by higher terrain

.41

Taking a cross section look (in three dimensions within Google Eart h) at the local area in

Figure 29 below, one can see the relationship of the local terrain with respect to the major

SO 2 sources in the region and the Liberty air monitor station.

Figure 29. Local Te rrain

From Figure 29 (which looks nor th to sou th), one can see that the Liberty air monitoring

station sits on top of a hill. However, there is higher terrain surrounding the monitor,

creating valley like influences. The main SO 2 sources in the region are at lower elevation

as they sit down within the river valley.

Figure 28 above shows that the Liberty monitor is centrally located between multiple

major SO 2 source s . The Liberty monitor acquires SO 2 samples from the air continuo usly

every hour, which results in approximately 8760 hours of samples every year. The latest

design value year, 2010 (which is based on data from 2008 to 2010), showed the Liberty

monitor exceeding the new SO 2 standard with a concentration of 128 ppb. Th e

Department analyzed the data to focus in on the hour s in which the SO 2 concentrations

exceeded the new 1

- hour SO 2 standard. 1 16 hours were found to exceed this threshold.

Out of those 1 16 hours, 116 hours had complete corresponding meteorological data.

Then, the Department analyzed the wind data and created a wind rose to coincide with

the meteorological data collected on those 116 hours that were found to exceed the new

1

- hour SO 2 standard threshold.42

Figure 30 shows the results.

Figure 30. Wi nd Rose Data for Exceedance Hours

W hen com paring this figure with Figure 28 above, one will notice that the primary wind

direction has changed. During the periods when there are high SO 2 concentrations, the

wind is primarily out of the south . In addition, wind speeds are generally strong er,

indicating that the winds are unimpeded (from any terrain) from that direction. As Figure

25 and Figure 26 displayed, the Allegheny County Airport location is not influenced by

higher terrain while the L iberty location is. The Allegheny County airport

meteorological tower is measuring winds at 55 meters above the Liberty meteorological

tower. Therefore, the stronger winds at the Allegheny County airport could potentially

signify the longer range transpo rt issue affecting the Liberty monitor.43

The time of the day when the SO 2 concentrations are occurring is also of importance.

Figure 31 illustrates when the Liberty monitor is experiencing the high 1

- hour SO 2

concentrations.

Figure 31. Time of Day f or SO 2 Exceedances

Most of the high SO 2 concentrations are occurring in the late evening to early morning

hours (from 10 PM to 8 AM). The timing of these exceedances coupled with the fact that

the Liberty monitoring site is situated within a valley in creases the likelihood that

meteorological inversions are assisting in driving SO 2 concentrations higher. Once an

inversion forms and the wind near the surface decreases (see Figure 6 for an example of

this), localized air pollution becomes trapped near t he surface. Therefore, there is even

more likelihood that the high SO 2 concentrations are driven by an SO 2 source in close

proximity to monitor. Note the rise in exceedances from 7 AM to 8 AM. This could

signify the regional transport of SO 2 in the regi on. Inversions usually begin to break

down during the late morning (in the 8 AM to 11 AM time frame). As the inversion

breaks, the air mass aloft mixes down toward the surface. If this air mass aloft has

elevated SO 2 concentrations within it, those high er concentrations will likely be picked

up by the monitor at the surface.

Due to the nature of the high SO 2 concentrations around the Liberty monitor, the

Departmen t is recommending that Allegheny County be designate d nonattainment for the

new SO 2 standard.44

Indiana County

Indiana County is situated within the western flank of the Appalachian Mountain chain.

Figure 32 below displays a topographical overview of all of Indiana County. There is

one major river that runs through the county. The Co nemaugh River, which runs across

southern Indiana County, forms the border between Indiana County and Westmoreland

County. Otherwise, then a few tributary streams, the county is primarily land.

Ultimately, t he meteorological pattern is driven by the high er terrain in the eastern half of

Indiana County.

Figure 32. I ndiana County Topographical Map45

Strongstown SO 2 Monitoring Location

Strongstown is situated on a portion of the higher terrain in the eastern side of Indiana

County. Figure 33 displays the location of the Strongstown monitor with respect to the

major SO 2 sources. In addition, Figure 2 highlights the terrain above the anemometer of

height o f the Strongstown meteorological tower (anemometer is at 10 meters plus base

elevation of tower at 580 meters). Therefore, the measurements being taken by the

Strongstown meteorological tower are likely to be influenced by t he higher terrain to its

east

.

Figure 33. Strongstown (Indiana County) Topographical Map46

Figure 3 4 (courtesy of G oogle Earth) displays a zoomed in look at the actual Strongstown

monitoring location with respect to the other regional SO 2 sources.

Figure 3 4. Strongstown Monitoring Location47

The impact of the topography near Strongstown can also be seen by looking at the wind

measurements that were collected at the Strongstown air monitoring station

( meteorological data, including wind direction and speed, are continuously measured).

Figure 35 (courtesy of Google Earth) displays the wind data measured at Strongstown’s

meteorological tower from January 2008 to December 2010 (a full three year dataset).

Figure 35. Wind Rose for the Strongstown Monitor

T he wind is primarily out of the west. There is also a strong influence of northeasterly

winds. Generally, t his wind profile follows the synoptic wind flow over the region and is

n ot surprising by seeing Figure 34 above, which shows that there is not any significant

terrain to the west of Strongstown that is influencing the wind measurements.48

Taking a cross section look (in three dimensions within Google Eart h) at the local area in

Figure 3 6 below, one can see the relationship of the local terrain with respect to the major

SO 2 sources in the region and the Strongstown air monitor station.

Figure 3 6 . Local Terrain

From Figure 3 6 (which looks south to north), once again one can see that the

Strongstown air monitoring station sits on top of a local hill

.

From Figure 3 5 above, one can see that the Strongstown monitor lies to the east of

several major SO 2 source s . The Strongstown monitor acquires SO 2 samples from the air

continuously every hour, which results in approximately 8760 hours of samples every

year. The latest design value year, 2010 (which is based on data from 2008 to 2010),

showed the Strongstown monitor exceeding the new SO 2 standard with a concentration of

90 ppb. The Department analyzed the data to focus in on the hour s in which the SO 2

concentrations exceeded the new 1

- hour SO 2 standard. 25 hours were found to exceed

this threshold. Out of those 74 hour s, 23 hours had complete corresponding

meteorological data. Then, the Department analyzed the wind data and created a wind

rose to coincide with the meteorological data collected on those 23 hours that were found

to exceed the new 1

- hour SO 2 standard threshold.49

Figure 3 7 shows the results.

Figure 3 7 . Wind Rose Data for Exceedance Hours

W hen com paring this figure with Figure 3 4 above, one will notice that the primary wind

direct ion has generally stayed the same . During the periods when there are high SO 2 concentrations, the wind continues to be primarily out of the west . In addition, wind

speeds are generally strong er, indicating that the high SO 2 concentrations are being

drive n in from further distances away

. Comparing the strong westerly component of the

winds with the fact that there are no other major SO 2 emissions sources within

Pennsylvania in close proximity of the Strongstown monitor indicates that the

Strongstown monit or is picking up on the interstate transport of SO 2 . Overall, the

prominent w esterly winds and strong er wind speeds are indicating that the driving source

of the higher SO 2 concentrations is coming from the larger SO 2 sources (these types of

sources generally have taller stacks and higher emission rates which helps in the

downwind transport of pollution) to the west of Strongstown

.50

The time of the day when the SO 2 concentrations are occurring is also of importance.

Figure 3 8 illustrates when the Strongstown monitor is experiencing the high 1

- hour SO 2

concentrations.

Figure 38 . Time of Day for SO 2 Exceedances

Most of the high SO 2 concentrations are occurring in the middle of the day hours (from 9

AM to 2 PM). The timing of these exceedances coupled with the fact that the

Strongstown monitoring site is situated on higher terrain increases the likelihood that

interstate transport is playing a role in the monitored SO 2 concentration exceedances.

The middle of the day is when the atmosphere is the most unstable, meaning that more

horizontal and vertical mixing is occurring. The onset of this mixing usually occurs in

the late morning when, after a cool night, the sun warms the surface. The air at the

surface is th en warmer and less dense than its surroundings so it wants to rise, inducing

vertical motion. The top two hours when we see the most exceedances are 11 AM and 12

PM, when vertical mixing begins. Therefore, there is even more likelihood that the high

SO 2 concentrations are driven by SO 2 sources to the west of the Strongstown monitor.

Due to the nature of the high SO 2 concentrations around the Strongstown monitor, the

Departmen t is recommending that Indiana County be designate d nonattainment for the

new SO 2 standard

.51

5 . Jurisdictional and o ther b oundaries

At this time, the Department is recommending that county boundaries be used to define

areas for designation purposes. EPA has indicated that the presumptive county boundary

will serve as the no nattainment area unless evidence indicates that a different planning

area is justified. Inventory data for non

- point sources is more accurate and available on

the county level which will be useful in meeting the requirements in nonattainment areas

for emi ssion inventory information and for reasonable further progress (incremental

emission reductions). The Department is using EPA’s presumptive county assumption

to recommend the boundaries of nonattainment areas associated with monitors violating

the 1

- hou r SO 2 standard. The Department will be conducting refined modeling to better

characterize boundaries relating to nonattainment and attainment areas.52



### Acronyms and Terms

AERMOD A MS/ E PA R egulatory Mod el

AMS American Meteorological Society

CAA Clean Air Act

CFR Code of Federal Regulations

DEP Department of Environmental Protection (Pennsylvania)

EGU Electric Generating Unit

EPA Environmental Protection Agency (United States)

FGD flue gas desulfurization

IPM Integrated Planning Model

MSA Metrop olitan Statistical Areas

NAAQS National Ambient Air Quality Standards

NEEDS National Electric Energy Data System

OMB Office of Management and Budget (United States)

ppb parts per billion

SIP State Implementation Plan

SO 2 Sulfur dioxide

tpy tons per year

U.S.C. United States Code53



### References

EPA, Final Rule, “ Primary National Ambient Air Quality Standards for Sulfur

Dioxide ,” ( 75 F R 35,520; June 22, 2010)

EPA, Area Designations for the 2010 Revised Primary Sulfur Dioxide National

Ambient Air Q uality Standards

, from Stephen D. Page, Director, EPA Office of

Air Quality Planning and Standards, March 24, 2011.

The DEP’s “

Ambient Air Monitoring Network Plan

– 201 1 ” (June 25 , 20 10 )

http://www.dep.state.pa.us/dep/deputate/airwaste/aq/aqm/principal.ht m

The Philadelphia Air Management Services’ (AMS) “ 20 10 /201 1 Air Monitoring

Network Plan ” (July 1, 20 10 ) http://www.phila.gov/health/AirManagement/

The Allegheny County Health Department’s (ACHD) “ Monitoring Network

Review ” ( July 1, 2010 ) http://www.achd.net/air/index.html

EPA Aerometric Information Retrieval System (AIRS), Air Quality System,

http://www.epa.gov/air/data/index.html

EPA National Electric Energy Data System (NEEDS) v.4.10

http://www.epa.gov/airmarkets/progsregs/epa

- ipm/BaseCasev410.html#needs

Office of Management and Budget, notice of decision, 2010 Standards for Delineating

Metropolitan and Micropolitan Statistical Areas (75 Fed. Reg. 37,246 (June 28, 2010 and

corrected July 7, 2010)

. The updated list of statistical areas is available at the following

website: www.census.gov/population/www/metroareas/metrodef.html

Office of Management and Budget, Bulletin No. 10

- 2, “ Update of Statistical

Area Definitions and Guidance on Their Uses ,” December 2009.

U.S. Census Bureau, Geography Division, Cartographic Products Management Branch,

Metropolitan and Micropolitan Statistical Areas Wall Maps, November 200 8.

htt p://www.census.gov/geo/www/maps/msa_maps2008/us_wall_1108.html