Technical Support Document (TSD) For 

Emissions Inventories for the Delaware Nonattainment Area

Particulate Matter (PM2.5) State Implementation Plan (SIP) Base Year Inventory.

Submitted June 2007 by the 

Delaware Department of Natural Resources

And Environmental Control (DNREC)

TSD Prepared April, 2010

Janet C. Kremer

Office of Air Monitoring and Analysis, 3AP40

U.S. Environmental Protection Agency, Region 3

1650 Arch Street

Philadelphia, Pennsylvania 19103

/s/

____________________________________________

Reviewed by Walter Wilkie, Associate Director

Office of Air Monitoring and Analysis, 3AP40

June 16, 2010

_________________

Date Signed

 
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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 emissions inventories submitted 

with the Delaware Nonattainment Area PM2.5 SIP by DNREC. This review determines

the approvability of the SIP Base Year Inventory and an evaluation of the methods used 

for projection year inventories. 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. 

Projection year inventories are essentially used to track progress; the purpose of which is 

to demonstrate a reduction in emissions of regulated sources from the Base Year to a 

projected year. The Delaware Nonattainment Area was designated as a PM2.5

nonattainment area in 2004. DNREC has submitted the Delaware Nonattainment Area 

PM2.5 SIP and has requested EPA’s approval.

Any questions pertaining to this technical summary should be directed to Walter 

K. Wilkie, Associate Director, Office of Air Monitoring and Analysis, at 215-814-2150 

or via email at wilkie.walter@epa.gov. 

II. 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.1 The base year inventory includes emissions estimates from stationary point 

and nonpoint sources, onroad mobile sources, and nonroad mobile sources. For the PM2.5

NAAQS, the pollutants to be inventoried are NH3, PM10, PM2.5, VOC, NOx and SO2. For 

the NAAQS, NH3, PM10, PM2.5, VOC, NOx and SO2 emissions should be reported as 

actual annual emissions. DNREC’s base year inventory is for 2002. For the Delaware 

SIP, the geographic coverage includes sources in New Castle County. A significant 

amount of documentation is required for these SIP base year estimates which DNREC

has provided. 

DNREC’s Emission Inventory Development (EID) Program (which resides within 

the Air Quality Management Section (AQMS)) was primarily responsible for preparing 

the 2002 base year PM2.5 precursor inventory. The point source inventory represents 

facility-specific data for larger stationary sources. Point source emissions data are 

submitted to AQMS by the facilities using Terminal Server Satellite i-STEPS software.

i-STEPS are the point source emission inventory electronic data management system. 

The criteria used to determine if a source would be a part of the point source inventory

was as follows: 

 

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“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
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 Facilities that held a Title V permit in 2002; 

 Any facility with emissions of VOCs greater than 5 TPY for any of the 

years 1999, 2000, or 2001, as previously reported to the AQMS inventory 

program; 

 Any facility falling into one of the following industry sectors: 

o Hot-mix asphalt plants, 

o Hospitals that use ethylene oxide for sterilization, 

o Electric generating units (EGUs); and 

o Facilities using anhydrous ammonia as a refrigerant; 

 Any facility for which AQMS does not have previous inventory data that 

appears may be a significant source. 

DNREC provided its 2002 actual annual emissions at the facility level and at the processlevel. 

For the 2002 Nonpoint Source emissions, also known as “area sources,” DNREC

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 calculated on an annual basis. Various sources of emission factors 

or methodologies were used, including EPA’s AP-42, the Factor Information Retrieval 

System (FIRE), EPA’s Emissions Inventory Improvement Program, Volume III,

documented projects performed by the California Air Resource Board, and projects 

performed by the Mid-Atlantic Regional Air Management Association (MARAMA).

Nonpoint source estimates were provided by SCC.

The Nonroad Mobile Source 2002 annual inventory was prepared with EPA’s 

NONROAD2005 model by E.H. Pechan and Associates under contract from the Mid 

Atlantic/Northeast Visibility Union (MANE-VU) using Delaware specific inputs.

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. 

DNREC provided emission estimates for locomotive engines, aircraft emissions and 

commercial marine vessels separately. For line haul locomotive and yard locomotive

emissions, DNREC requested and received estimates of fuel consumption or data to 

calculate fuel consumption. Some information was provided at county level for each 

county in Delaware, while some was provided system-wide and needed to be allocated to 

Delaware. Track miles within each county were used to allocate statewide fuel 

consumption to each county. Paired with EPA emission and conversion factors, DNREC

calculated locomotive annual emissions for the base year. For aircraft emissions,

DNREC took airport-specific emissions for all aircraft sub-categories and allocated them 

to the county in which each airport is located. DNREC estimated annual aircraft 

emissions using a combination of airport-specific activity data and Federal Aviation 

Administration (FAA)/EPA emission factors. DNREC requested landing and take-off 

data from the Delaware Aeronautics Administration and from individual airports, for 

each sub-category of aircraft. DNREC used these airport-specific LTO data to estimate 

emissions using FAA’s Emissions and Dispersion Modeling System (EDMS). EDMS 

does not estimate particulate emissions by aircraft/engine type. DNREC used fleet average 
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PM10 emission rates applied to total LTOs outside EDMS. For commercial marine vessels, 

there are many types of vessels that engage in many different modes of activity, therefore 

DNREC used several different sources to obtain data for each vessel type and activity. 

Some of these sources included the Marine Exchange of the Delaware River (ME, 2004), 

the Commercial Marine Activity for Deep Sea Ports in the United States (EPA, 1999), 

and the Waterborne Commerce of the United States (USACE, 2004a). Annual emissions 

were calculated by vessel type, engine type, and mode of operation using county level 

activity data. All Nonroad mobile source emissions were provided by SCC.

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 

(M6.2) and link-level vehicle miles traveled (VMT) data for each county from the 

Delaware Department of Transportation (DelDOT). The emission factors developed 

using M6.2, were by month, using monthly temperature and fuel property data. DNREC 

provided Mobile6.2 input and output files for review. DNREC provided annual mobile 

emissions values in Tons Per Year (TPY) and were provided by SCC.

DNREC also applied rule effectiveness and rule penetration for its 2002 PM2.5

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). DNREC applied rule effectiveness and where applicable, provided a 

justification of a higher percentage than EPA’s previous policy (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. DNREC applied rule penetration for its nonpoint 

sources where applicable.

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

year, and found them to be approvable.