Technical Support Document (TSD) For the 20II Base Year Inventory ForAreas ofMarginal Nonattainment ofthe2008 Ozone NAAQS in Delaware

Submitted April 20I5 by the Delaware Department ofNatural Resources and Environmental Control

TSD Prepared August 20I5 by Jessica L. Fry Office ofAir Monitoring and Analysis, 3AP40 U.S. Environmental Protection Agency, Region 3 I650 Arch Street Philadelphia, Pennsylvania I9I03

Office ofAirMonitoring and Analysis (3AP40)I. Introduction

The purpose ofthis document is to provide atechnical summary ofthe Office of Air Monitoring and Analysis (OAMA) review ofthe 2011 Base Year Inventory submittedfor areas ofmarginal nonattainrnent ofthe 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 containsNewCastle County, DE, and Sussex County, DE was designated nonattainrnent

as a stand-aloneNAA, calledthe Seaford Marginal NAA. EPA designated the NAAs as marginal for the 2008 OzoneNAAQS effective July 20, 2012. This requires the area to submit a comprehensive base year inventory no laterthan 24 months from the July 20, 2012 effective date and everythree 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 ofan 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 orderto fulfill the CAA requirements. Any questions pertainingto this technical summary shouldbe directed to Alice H. Chow, Associate Director, Office ofAir Monitoring and Analysis, at 21'5-814- 2144 orviaemail 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 ofactual 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 ofall

sources ofozone precursors no later than 2 years after the effective date ofdesignation. This inventory contains actual annual emissions and typical ozone season day emissions for the ozone season ofMaythrough September for the ozoneprecursors, NOx, CO,and VOC. The base year inventory includes emissions estimates from stationary point and nonpoint sources, onroadmobile sources, and nonroad mobile sources.

DNREC'sDivision ofAir 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 shouldbe used for purposes ofthe 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.

Forthe 2011 nonpoint source emissions, also known as "area sources," DNREC DAQ provided an inventory that contains estimations ofemissions by multiplying an emission factor by some known indicator ofcollective 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 theseannual emissionsto seasonal emissions. The summer ozone season is defined as May through September.

The 2011 nonroad mobile source inventory was prepared by DAQ withEPA's NONROAD2008amodel. 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 ofemissionfactors from EPA and the Federal Aviation Administration (FAA) as well as airport-specific activity data were used in the model. Locomotive emissions were calculatedusing companyprovided fuel consumption data. Commercial Marine Vessel emissions were calculatedusing specific activity and operation data for eachvessel. 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'sNational Emissions Inventory (NEI), version 1for their onroad inventory. Documentation for the 2011 NEI canbe found at http://www.epa.gov/ttnlchief/net/2011inventory.html.

OAMA staffreviewedthe results, procedures, and methodologies for the SIP base year, and found them to be acceptable.