Technical Support Document (TSD) For the 

20 II Base Year Inventory 

For Areas of Marginal Nonattainment ofthe 2008 

Ozone NAAQS in Delaware 

Submitted April 20 I5 by the 

Delaware Department of Natural Resources and Environmental Control 

TSD Prepared August 20 I5 by 

Jessica L. Fry 

Office of Air Monitoring and Analysis, 3AP40 

U.S. Environmental Protection Agency, Region 3 

I650 Arch Street 

Philadelphia, Pennsylvania I9I 03 

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 of the 2011 Base Year Inventory 

submitted for areas of marginal nonattainrnent of the 2008 Ozone NAAQS in Delaware 

(DE), submitted by the Delaware Department ofNatural Resources and Environmental 

Control (DNREC). There are two marginal nonattainrnent areas (NAAs) for the 2008 

Ozone NAAQS in Delaware. The Philadelphia-Wilmington-Atlantic City Marginal NAA 

contains New Castle County, DE, and Sussex County, DE was designated nonattainrnent 

as a stand-alone NAA, called the Seaford Marginal NAA. EPA designated the NAAs 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. DNREC has submitted a 2011 

Base Year Inventory for the two Delaware NAAs 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 21'5-814-

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, nonroad, and 

onroad) in the nonattainment area. The CAA section 182(a)(1) 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 and typical ozone season day emissions 

for the ozone season of May through September for the ozone precursors, NOx, CO, and 

VOC. The base year inventory includes emissions estimates from stationary point and 

nonpoint sources, onroad mobile sources, and nonroad mobile sources. 

DNREC's Division of Air Quality (DAQ) 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. 

DAQ developed their 2011 inventory by using emissions directly reported to the agency 

by the facilities. Annual emissions and ozone season day emissions were reported. The 

emissions were provided at the facility level and process-level. 

For the 2011 nonpoint source emissions, also known as "area sources," DNREC 

DAQ 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 level. These emissions are typically calculated on an annual basis because 

the activity data are generally only available on an annual basis. DAQ converted these 
annual emissions to seasonal emissions. The summer ozone season is defined as May 

through September. 

The 2011 nonroad mobile source inventory was prepared by DAQ with EPA's 

NONROAD2008a model. NONROAD estimates fuel consumption and emissions for all 

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

marine vessels. Aircraft emissions were estimated using the Federal Aviation 

Administration's (FAA) Emissions and Dispersion Modeling System (EDMS), Version 

5 .1.4.1. A combination of emission factors from EPA and the Federal Aviation 

Administration (FAA) as well as airport-specific activity data were used in the model. 

Locomotive emissions were calculated using company provided fuel consumption data. 

Commercial Marine Vessel emissions were calculated using specific activity and 

operation data for each vessel. Annual emissions and ozone season day emissions were 

reported. 

The onroad mobile source 2011 emissions inventory was developed using the 

EPA's highway mobile source emissions model MOVES 2010a. DAQ has submitted 

EPA's National Emissions Inventory (NEI), version 1 for their onroad inventory. 

Documentation for the 2011 NEI can be found at 

http://www.epa.gov/ttnlchief/net/20 11 inventory.html. 

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

year, and found them to be acceptable.