Technical Support Document (TSD) For 

Emissions Inventories for the Pittsburgh – Beaver Valley Pennsylvania 

8 Hour Ozone Redesignation Request, Maintenance Plan, and,

State Implementation Plan (SIP) Base Year Inventory.

Submitted May 2007 by the Pennsylvania 

Department of Environmental Protection 

TSD Prepared May 2007 by

Janet C. Kremer

Air Quality Analysis Branch, 3AP22

U.S. Environmental Protection Agency, Region 3

1650 Arch Street

Philadelphia, Pennsylvania 19103

_________________/S/________________________

Reviewed by Walter Wilkie, Chief

Air Quality Analysis Branch (3AP22)

_____5/30/07______

Date Signed

        

Introduction

The purpose of this document is to provide a technical summary of the
Air Quality Analysis Branch’s (AQAB) review of the emissions
inventories submitted with the Pittsburgh – Beaver Valley,
Pennsylvania 8 Hour Ozone Redesignation Request, Maintenance Plan and
State Implementation Plan (SIP) Base Year Inventory by the Pennsylvania
Department of Environmental Protection (PADEP).  This review does not
determine the approvability of the Redesignation Request or Maintenance
Plan; but it does determine the approvability of the SIP Base Year
Inventory.  Emissions inventories in a redesignation request are used to
show permanent and enforceable emission reductions between the year the
area was designated as a  nonattainment area and the year the area came
into attainment.  In a maintenance plan, the emissions inventories are
used to reflect the emissions during the time the area came into
attainment and are then projected to show that the area will remain in
attainment.  A SIP Base Year Inventory is the starting point from which
other SIP inventories are derived as well as serving as the benchmark
for other SIP planning activities, such as the establishment of an
emissions reduction credit program.  The Pittsburgh – Beaver Valley
Area, which consists of Allegheny, Armstrong, Beaver, Butler, Fayette,
Washington, and Westmoreland Counties, was designated as an 8 hour ozone
nonattainment area with a Subpart 1 classification.  Subpart 1 area(s)
are required to submit SIP base year inventories to EPA by June 15,
2007.  PADEP has included this early submission of SIP base year with
the redesignation request and maintenance plan package and has requested
EPA’s approval.

Any questions pertaining to this technical summary should be directed to
Walter K. Wilkie, Chief, Air Quality Analysis Branch, at 215-814-2150 or
via email at   HYPERLINK "mailto:wilkie.walter@epa.gov" 
wilkie.walter@epa.gov . 

II 	Emissions Inventories for Redesignation Request (Base Year
Inventory)

	In a redesignation request, emissions inventories are used to support
the States claim that the area has permanent and enforceable emissions
reductions.  In order to do this, the state should estimate the percent
reduction (from the year that was used to determine the design value for
designation and classification) achieved from federal and state control
measures; this is usually termed as the “base year” inventory. The
base year inventory contains VOC and NOx emissions for all source
categories, which includes point, area, onroad mobile, and nonroad
mobile for the ozone season.  

 

	In the Pittsburgh - Beaver Valley redesignation request, the base year
used was 2002.  The Point Source data for 2002 is derived from the
Pennsylvania Air Information Management System (AIMS).  The AIMS
database is comprised of sources identified and inventoried by PADEP’s
regional and central offices through permitting, field inspections, and
surveys.  Surveys are conducted annually as facilities must submit
emission estimates for various operations, throughputs, work hours, as
well as process data, such as combustion unit data and fuel
characteristics. For its redesignation request, PADEP provided its 2002
actual summer weekday emissions for NOx and VOC at the facility level
and by Source Classification Codes (SCCs).  “Summer weekday
emissions” is defined by PADEP as an average day’s emissions for a
typical summer day during the ozone season.  

	For the 2002 Nonpoint Source emissions, also known as “area
sources,” PADEP provided an inventory that contained estimations of
emissions by multiplying an emission factor by some known indicator or
activity level for each category at the county level.  These emissions
are typically calculated on an annual basis because the activity data
are generally only available on an annual basis.  PADEP further
converted these annual emissions to seasonal emissions, for ozone, the
summer season is defined as peak ozone season months of June, July, and
August.  Seasonal estimates were calculated using default monthly and
weekly profiles from EPA’s Emissions Modeling Clearing House (EMCH). 
Nonpoint source estimates were provided by SCC.

	The Nonroad Mobile Source 2002 inventory was prepared with EPA’s
NONROAD2005 model.  NONROAD estimates fuel consumption and emissions of
total hydrocarbons, carbon monoxide, nitrogen oxides, sulfur dioxide,
and particulate matter for all nonroad mobile source categories except
for aircraft, locomotives, and commercial marine vessels.  PADEP
provided emission estimates for locomotive engines and aircraft
emissions separately.  For locomotive engine emissions, PADEP projected
emissions from a 1999 survey using national fuel consumption information
and EPA emission and conversion factors.  Emissions from commercial
aircraft emissions were estimated using the EPA’s Emissions and
Dispersion Modeling System (EDMS).  Commercial aircraft operations were
modeled directly by EDMS for Pittsburgh International Airport and a
small amount from Arnold Palmer Regional Airport.  Small aircraft
emissions were calculated by using small airport operation statistics,
which can be found at ww.airnav.com.  All Nonroad mobile source
emissions were provided by SCC and classification.

	The Onroad Mobile Source 2002 emissions inventory was developed using
the most current version of EPA’s highway mobile source emissions
model MOBILE 6.2. PADEP also used PPSUITE, an enhanced version of the
Post Processor for Air Quality software systems used for previous
inventory and conformity submissions in Pennsylvania.  Traffic data
source and fleet data inputs were supplied by the 2002 PENNDOT Roadway
Management System.  PADEP provided Mobile6.2 input and output files for
review as a part of their redesignation request.  Mobile emissions
values were given in units of tons per summer day and were provided by
SCC.

AQAB staff reviewed the files and the emission results provided by PADEP
and found them to be reasonable for use in this redesignation request.

III.	Emissions Inventories for Maintenance Plan

2004 Attainment Year Inventory and Maintenance Plan Base Year Inventory

As stated earlier, emissions inventories are used to show emission
reductions for the area between the year of designation to nonattainment
and the year of attainment.  The inventory used for the year of
attainment is called the Attainment Year Inventory and also is referred
to as the Maintenance Plan Base Year Inventory.  This inventory is used
as the basis for the projected inventories that are used to show the
area will remain in attainment.  This section will discuss the 2004
Attainment Year Inventory that was used in the Pittsburgh - Beaver
Valley Redesignation Request and Maintenance Plan submitted by PADEP.

PADEP compiled an actual 2004 Point Source inventory for the Pittsburgh
- Beaver Valley Redesignation Request and Maintenance Plan.  The 2004
point source inventory contained point source emissions derived from the
Pennsylvania Air Information Management System (AIMS).  As previously
discussed, AIMS houses all point source data compiled by various
programs (permitting, enforcement, etc.).  For its redesignation
request, PADEP provided its 2004 actual summer weekday emissions for NOx
and VOC at the facility level and by Source Classification Codes (SCCs).
 “Summer weekday emissions” is defined by PADEP as an average
day’s emissions for a typical summer day during the ozone season.  

For the 2004 Nonpoint Source emissions, PADEP provided a projected
inventory from the 2002 inventory.  The factors used for the temporal
allocation of projections were provided by the Mid-Atlantic Regional Air
Management Association (MARAMA).  The factors were from EPA’s Sparse
Matrix Operator Kernel Emissions (SMOKE) v2.2 input files.  Data from
2004 area sources is a linear interpolation of between the 2002 base
year and the 2009 projected inventory.  Emissions were provided by SCC
and units were in tons per summer day.

	The 2004 emissions for Nonroad Mobile Source emissions were estimated
using the EPA NONROAD2005 model.  The NONROAD model estimates emissions
of total hydrocarbons, carbon monoxide, nitrogen oxides, sulfur dioxide,
and particulate matter for diesel, gasoline, liquefied petroleum
gasoline and compressed natural gas-fueled nonroad equipment categories.
 Locomotives and aircraft were developed separately by PADEP.  Just as
with the 2002 nonroad inventory, for locomotive emissions in 2004, PADEP
projected emissions from a 1999 survey using national fuel consumption
information and EPA emission and conversion factors.  For commercial
aircraft emissions, PADEP estimated emissions by growing the 2002
emissions modeled in EDMS using operations projection in the Federal
Aviation Administration’s APO Terminal Area Forecast Detailed Report. 
Nonroad mobile source emissions were provided by SCC and classification
and were given in units of tons per summer day.

	The Onroad Mobile Source 2004 emissions inventory was developed using
the most current version of EPA’s highway mobile source emissions
model MOBILE 6.2.  In addition, PADEP uses a MOBILE pre- and post-
processing software package, PPSUITE, to process and compile
Pennsylvania’s highway data.  PPSUITE has been used in previous
inventory and conformity submittals from Pennsylvania.  Traffic data
source and fleet data inputs were supplied by the 2002 PENNDOT Roadway
Management System.  PADEP provided sample Mobile6.2 input and output
files for review.  Mobile emissions values were given in units of tons
per summer day and were provided by SCC.

AQAB staff reviewed the files and emission results and believes them to
be reasonable for use in the maintenance plan. 

2009 and 2018 Projection Emission Inventories

Projection inventories are used to show that the area will remain in
attainment.  Projection inventories for the years 2009 and 2018 were
used for the Pittsburgh - Beaver Valley Maintenance Plan.  Inventories
were developed for all emission sources for both years.

PADEP used projection inventories for point and nonpoint sources
prepared by MACTEC Federal Programs, Inc., for the Mid-Atlantic Regional
Air Management Association (MARAMA).  MACTEC’s projected inventories
were from 2002, not 2004. PADEP’s 2004 inventory was not available at
the time of MACTEC’s work.

The Point Source emissions for 2009 and 2018 were projected, for both
EGUs and non EGUs, using growth factors from EPA’s Economic Growth and
Analysis System, Version 5.0 (EGAS 5.0) and the Department of Energy’s
Annual Energy Outlook 2005 fuel consumption forecasts.  In addition, for
non-EGUs, state-supplied population, employment and other emission
projection data were also applied to account for changes in economic
activity.  Then, control factors were applied to account for future
emission reductions from on-the-books (OTB) control regulations and
on-the-way (OTW) control regulations.

	The Nonpoint Source emissions for 2009 and 2018 were projected using
growth factors to account for population and economic activity.  Then,
as with point sources, control factors were used to account for future
emission reductions from on-the-books (OTB) control regulations and
on-the-way (OTW) control regulations. 

For the 2009 and 2018 Nonroad Mobile Source inventories, PADEP used
EPA’s NONROAD2005 model to generate these future inventories.  The
NONROAD model allows for the calculation of past year, present year, and
future year inventories (up to the year 2050) to be generated.  Growth
for locomotives came from the Association of American Railroads and
compared well with EGAS; and, commercial aircraft growth was estimated
from the Federal Aviation Administration’s APO Terminal Area Forecast
Detailed Report.  

The 2009 and 2018 Onroad Mobile Source inventories were generated using
EPA’s MOBILE6.2.  In addition, PADEP used a PENNDOT study completed in
2005, “Statistical Evaluation of Projected Traffic Growth, Traffic
Growth Forecasting System:  Final Report, March 14, 2005” that
provided information used to forecast traffic volumes.  Growth rates for
vehicle miles traveled (VMT), and four functional road classifications
in each Pennsylvania county:  urban interstate, urban non-interstate,
rural interstate, and rural non-interstate were incorporated with
traffic data and socioeconomic forecasts which is inputted in PPSUITE to
calculate VMT and speeds; the output is then run in MOBILE6.2 to
calculate emissions.

AQAB staff reviewed the procedures, and found them to be reasonable for
development of these inventories.  

IV.	2002 SIP Base Year Inventory

	The SIP base year inventory is the primary inventory from which other
inventories (3-year cycle inventories, reasonable further progress
inventories, modeling inventories) are derived.  The Clean Air Act calls
for State, local, and Tribal agencies to ensure that the base year
inventory is comprehensive, accurate, and current for all actual
emissions.  The base year inventory includes emissions estimates from
stationary point and nonpoint sources, onroad mobile sources, and
nonroad mobile sources.  For the 8-hour ozone NAAQS, the pollutants to
be inventoried are VOC, NOx and CO (carbon monoxide).  For the 8-hour
ozone NAAQS, VOC, NOx and CO emissions should be reported as actual
annual and actual summer weekday emissions (defined as an average
day’s emissions for a typical summer day during the ozone season). 
PADEP’s base year inventory is for 2002.  A significant amount of
documentation is required for these SIP base year estimates which PADEP
has provided.  

In the case of Pittsburgh - Beaver Valley, it was designated as an 8
hour ozone nonattainment area with a Subpart 1 classification.  Subpart
1 area(s) are required to submit SIP base year inventories to EPA by
June 15, 2007.  PADEP elected to include this early submission of the
SIP base year with its redesignation request and maintenance plan
package and has requested EPA’s approval.

	PADEP’s methodologies concerning the generation of point, nonpoint,
onroad mobile and nonroad mobile emissions for the SIP base year are the
same as for the 2002 base year redesignation request.  However, EPA
guidance required, in addition to the NOx and VOC summer day emissions,
annual emissions for NOx and VOCs.  Further, the EPA guidance required
annual and summer day estimates for CO.  

	PADEP also applied rule effectiveness and rule penetration for its 2002
8-hour ozone SIP base year inventories.  Rule effectiveness reflects the
actual ability of a regulatory program to achieve the emission
reductions required by regulation (or perhaps voluntarily adopted).  In
the 2005, EPA developed recommendations to revise EPA’s existing rule
effectiveness guidance; due to the fact that PADEP’s inventory was
developed prior to the issuance of the new rule effectiveness policy,
EPA’s previous policy was followed, which assumed an 80% rule
effectiveness for applicable sources unless otherwise specified.  Rule
penetration is an estimate of percentage of emissions in a source
category that are emitted at facilities subject to the requirements of a
rule.  PADEP applied rule penetration for its nonpoint sources at 60%.

AQAB staff reviewed the results, procedures, and methodologies for the
SIP base year, and found them to be approvable.  The following table
summarizes PADEP’s 2002 SIP Base Year for Pittsburgh - Beaver Valley.

Pittsburgh 2002 SIP Base Year













 	VOC Emissions	NOx Emissions	CO Emissions

Source Type	Tons/yr	Tons/day	Tons/yr	Tons/day	Tons/year	Tons/day

Point Sources	6134.0	16.5	92842.2	250.4	50966.0	134.5

Nonpoint Sources 	40162.6	100.3	33052.2	11.5	33052.2	61.6

Onroad Mobile Sources	29285.5	86.4	493445.8	173.9	493445.8	630.1

Nonroad Mobile Sources	15193.1	51.5	174583.3	86.1	174583.3	1105.6

TOTAL Emissions	90775.2	254.7	793923.5	521.9	752047.3	1931.8



 “Emissions Inventory Guidance for Implementation of Ozone and
Particulate Matter National Ambient Air Quality Standards (NAAQS) and
Regional Haze Regulations” EPA-454/R-05-001, August 2005

