Technical Support Document (TSD) For the 

2011 Base Year Inventory 

For the 

Washington DC-MD-V A 

2008 Ozone NAAQS Nonattainment Area 

Submitted July 2014 by the 

District Department of the Environment 

Maryland Department of the Environment, 

and 

Virginia Department of Environmental Quality 

TSD Prepared March 2015 by 

Jessica L. Fry 

Office of Air Monitoring and Analysis, 3AP40 

U.S. Environmental Protection Agency, Region 3 

1650 Arch Street 

Philadelphia, Pennsylvania 19103 

Reviewed by Alice H. Chow, Associate Director 

Office of Air Monitoring and Analysis (3AP40) 
I. Introduction 

The purpose of this document is to provide a technical summary of the Office of Air 

Monitoring and Analysis (OAMA) review ofthe 2011 Base Year Inventory submitted for 

the Washington DC-MD-VA Nonattainment Area (NAA) 2008 Ozone NAAQS by the 

District Department of the Environment (DDOE), the Maryland Department ofthe 

Environment (MDE), and the Virginia Department of Environmental Quality (VADEQ). 

EPA designated the NAA as marginal for the 2008 Ozone NAAQS effective July 20, 

2012. This requires the area to submit a comprehensive base year inventory no later than 

24 months from the July 20, 2012 effective date and every three years thereafter. 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. Under the Clean Air Act (CAA) 

sections 172( c )(3) and 182( a)( 1 ), states are required to submit emissions inventory 

information for all relevant sources for the areas that are designated nonattainment. The 

DDOE, MDE, and VADEQ herein referred to as "state air agencies," in collaboration 

with the Metropolitan Washington Council of Governments (MWCOG) have submitted 

the 2011 Base Year Inventory for the Washington DC-MD-VA 2008 Ozone NAAQS 

Nonattainment Area in order to fulfill the CAA requirements. Any questions pertaining 

to this technical summary should be directed to Alice H. Chow, Associate Director, 

Office of Air Monitoring and Analysis, at 215-814-2144 or via email at 

chow .alice@epa. gov. 

II 2011 Base Year Inventory 

Under section 172(c)(3) states are required to submit a comprehensive, accurate, 

current accounting of actual emissions from all sources (point, nonpoint, nomoad, and 

onroad) in the nonattainment area. The CAA section 182(a)(l) requires that areas 

designated as nonattainment and classified as marginal are to submit an inventory of all 

sources of ozone precursors no later than 2 years after the effective date of designation. 

This inventory contains actual annual emissions of primary PM2.s emissions (including 

condensibles), S02, NOx, CO, VOC, and NH3. Typical ozone season day emissions for 

the ozone season of May through September were submitted for NOx, CO, and VOC. The 

base year inventory includes emissions estimates from stationary point and nonpoint 

sources, omoad mobile sources, and nomoad mobile sources. For the NAA, the 

geographic coverage includes sources in the District of Columbia (DC); Calvert, Charles, 

Frederick, Montgomery, and Prince George Counties in Maryland (MD); and Arlington, 

Alexandria, Fairfax, Loudoun, and Prince William Counties in Virginia (VA). 

The state air agencies, in collaboration with MWCOG, developed the point source 

data for the 2011 base year inventory. The point source inventory contains emissions for 

EGU and Non-EGU sources in the NAA. EPA guidance for emissions inventory 

development provides that actual emissions should be used for purposes of the base year 

inventory. The state air agencies developed their 2011 inventory by using emissions 

directly reported by the facilities. MWCOG compiled the ozone season day and annual 

emissions provided the by the state air agencies and included them in the plan. The 

emissions were provided at the facility level and process-level. 
For the 2011 nonpoint source emissions, also known as "area sources," the state 

air agencies provided an inventory that contains estimations of emissions by multiplying 

an emission factor by some known indicator of collective activity for each source 

category at the county (or county-equivalent). These emissions are typically calculated on 

an annual basis because the activity data are generally only available on an annual basis. 

The state air agencies converted these annual emissions to seasonal emissions. The state 

air agencies defined the summer ozone season as May through September. 

The 2011 nonroad mobile source inventory was prepared by MWCOG with 

EPA's NONROAD2008 model. NONROAD estimates fuel consumption and emissions 

for all nonroad mobile source categories except for aircraft, locomotives, and commercial 

marine vessels. EPA'a NMIM2008 software (version NMIM20090504), the NMIM 

County Database (NCD20130531_nei2011 vl), and the NONROAD 2008a model (July 

2009 version) were run for the NAA for both an average ozone season day and annual 

emissions. The period May through September was considered for ozone season analysis, 

while four season approach was adapted for developing annual emissions. Emission 

estimates for locomotive engines, aircraft emissions and commercial marine vessels were 

provided separately. The state air agencies estimated emissions separately for these 

sources using local data for each of their respective counties. 

The onroad mobile source 2011 emissions inventory was developed using the 

EPA's highway mobile source emissions model MOVES 2010a. The National Capitol 

Region Transportation Planning Board (TBP) developed transportation related inputs and 

ran the model using fuel and inspection and maintenance program inputs provided by the 

state air agencies, and meteorology inputs developed by the Metropolitan Washington Air 

Quality Committee (MW AQC) staff. MW AQC staff reviewed and approved these 

emissions. 

OAMA staff reviewed the results, procedures, and methodologies for the SIP base 

year, and found them to be acceptable.