UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

REGION III

1650 Arch Street

Philadelphia, Pennsylvania 19103

DATE: February 22, 2012

SUBJECT: Technical Support Document - Delaware; Attainment Plan for the Delaware

Portion of the Philadelphia-Wilmington, Pennsylvania-New Jersey-Delaware 

 (PA-NJ-DE) 1997 Fine Particulate Matter Nonattainment Area

/s/

FROM: Rose Quinto, Environmental Engineer

Office of Air Program Planning

TO: File

 /s/

THRU: Cristina Fernandez, Associate Director

Office of Air Program Planning

This document provides a technical review of a revision to the Delaware State 

Implementation Plan (SIP) submitted by the Delaware Department of Natural Resources and the 

Environmental Control (DNREC) on April 3, 2008. This SIP revision addresses the attainment 

plan of the 1997 annual fine particulate matter (PM2.5) national ambient air quality standard 

(NAAQS) for the Delaware portion of the Philadelphia-Wilmington, Pennsylvania-New JerseyDelaware (PA-NJ-DE) nonattainment area (Philadelphia area). The attainment plan includes the 

Delaware portion of Philadelphia area’s attainment demonstration, motor vehicle emission 

budgets (MVEBs) used for transportation conformity purposes, an analysis of reasonably

available control measures (RACM) and reasonably available control technology (RACT), base 

year emissions inventory, and contingency measures.

This document also provides a technical review of a supplement to the April 3, 2008 

submittal, submitted by DNREC on November 17, 2011. This supplement submittal 1) replaces 

the onroad emissions budget in the April 3, 2008 submittal with a budget that is based on a new 

onroad mobile emissions model – Motor Vehicle Emissions Simulator (MOVES) model; 2) 

demonstrates that the MOVES based mobile source budget is consistent with attainment of the 

PM2.5 NAAQS by 2010; and 3) demonstrates that the contingency requirements of the CAA are 

met. This SIP revision only impacts PM2.5 and nitrogen oxides (NOx) emissions and 

calculations. DNREC requested EPA to process this supplemental submittal in parallel with the 

April 3, 2008 submittal, while DNREC completes the public procedures necessary to submit the 

amended PM2.5 attainment demonstration as a formal supplement to the April 3, 2008 submittal. 

If the proposed SIP revision is changed in areas other than those identified in the notice of 

proposed rulemaking action, EPA will evaluate those changes and may publish another notice of 

proposed rulemaking. If no changes are made, EPA will publish a final rulemaking notice on the 
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revisions. The final rulemaking action by EPA will occur only after the SIP revision has been 

adopted by Delaware and submitted formally to EPA for incorporation into the Delaware SIP.

A. BACKGROUND

I. Designation History

On July 18, 1997 (62 FR 36852), the Environmental Protection Agency (EPA)

established the 1997 PM2.5 NAAQS, including an annual standard of 15.0 micrograms per cubic 

meter (g/m3) based on a 3-year average of annual mean PM2.5 concentrations and a 24-hour (or 

daily) standard of 65 g/m3based on a 3-year average of the 98th percentile of 24-hour 

concentrations. EPA established the standards based on significant evidence and numerous 

health studies demonstrating that serious health effects are associated with exposures to PM2.5.

Following promulgation of a new or revised NAAQS, EPA is required by the Clean Air 

Act (CAA) to designate areas throughout the United States as attaining or not attaining the 

NAAQS; this designation process is described in section 107(d)(1) of the CAA. In 1999, EPA 

and State Air Quality Agencies initiated the monitoring process for the 1997 PM2.5 NAAQS and 

by January 2001, established a complete set of air quality monitors. On January 5, 2005 (70 FR 

944), EPA promulgated initial air quality designations for the 1997 PM2.5 NAAQS based on air

quality monitoring data for calendar years 2001-2003.

On April 14, 2005 (70 FR 19844), EPA promulgated a supplemental rule amending 

EPA’s initial designations, with the same effective date (April 15, 2005) as 70 FR 944. As a 

result of this supplemental rule, PM2.5 nonattainment designations are in effect for 39 areas, 

comprising 208 counties within 20 states (and the District of Columbia) nationwide, with a 

combined population of about 88 million. The Delaware portion of the Philadelphia area is 

included in the list of areas not attaining the 1997 PM2.5 NAAQS. The Delaware portion of the 

Philadelphia area consists of New Castle County.

It should be noted that on November 13, 2009 (74 FR 58688), EPA relabeled the existing 

designation tables in 40 CFR 81.308 to clarify the 1997 designations for the 24-hour PM2.5

NAAQS. The designation for New Castle County was clarified as unclassifiable/attainment for 

the 1997 24-hour PM2.5 NAAQS.

II. Clean Air Fine Particle Implementation Rule

On April 25, 2007 (72 FR 20586), EPA issued the Clean Air Fine Particle 

Implementation Rule for the 1997 PM2.5 NAAQS. The “PM2.5 Implementation Rule” describes 

the CAA framework and requirements for developing SIPs for areas designated nonattainment 

for the 1997 PM2.5 NAAQS. An attainment plan must include a demonstration that a 
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nonattainment area will meet the applicable NAAQS within the time provided in the statute. 

This demonstration must include modeling (40 CFR 51.1007) that is performed in accordance 

with EPA modeling guidance (EPA-454/B-07-002, April 2007). It must also include supporting 

technical analyses and descriptions of all relevant adopted Federal, state, and local regulations 

and control measures that have been adopted in order to provide attainment by the proposed 

attainment date. 

For the 1997 PM2.5 NAAQS, an attainment plan must show that a nonattainment area will 

attain the 1997 PM2.5 NAAQS as expeditiously as practicable, but within five years of 

designation (i.e. attainment date of April 2010 based on air quality data for 2007-2009). If the 

area is not expected to meet the NAAQS by April 2010, a state may request to extent the 

attainment date by one to five years based upon the severity of the nonattainment problem or the 

feasibility of implementing control measures (section 172(a)(2) of the CAA) in the specific area.

For EPA to approve an extension of the attainment date beyond 2010, the state must provide an 

analysis to support the request and demonstrate that the attainment date is as expeditious as 

practicable for the area given the facts and circumstances of the area and consistent with the 

statutory criteria for an extension.

For each nonattainment area, the state must demonstrate that it has adopted all RACM, 

including all RACT as needed to provide for attainment of the PM2.5 standards in the area “as 

expeditiously as practicable.” The PM2.5 Implementation Rule provides guidance for making 

these RACM and RACT determinations. Any measures that are necessary to meet these 

requirements that are not already Federally promulgated or in an EPA-approved part of the state’s

SIP must be submitted as part of the state’s attainment plan. Any state measures must meet the 

applicable statutory and regulatory requirements, and in particular, must be Federally

enforceable.

The PM2.5 Implementation Rule also includes guidance on pollutants that states must 

address in their attainment plans. Section 302(g) of the CAA authorizes EPA to regulate criteria 

pollutants and their precursors. In the case of PM2.5, the main chemical precursors are sulfur 

dioxide (SO2), NOx, ammonia (NH3), and volatile organic compounds (VOCs). The effect of 

reducing emissions of precursor pollutants that contribute to PM2.5 concentrations varies by area, 

however, depending on PM2.5 composition, emission levels, and other area-specific factors. For 

this reason, the PM2.5 Implementation Rule provided guidance recommending that states elect to 

control direct PM2.5 emissions and the precursor or precursors that would be most effective for 

attaining the NAAQS within the specific area, based upon an appropriate technical 

demonstration.

In accordance with the PM2.5 Implementation Rule, direct PM2.5 emissions means “solid 

particles emitted directly from an air emissions source or activity, or gaseous emissions or liquid 

droplets from an air emissions source or activity which condense to form particulate matter at 

ambient temperatures. Direct PM2.5 emissions include elemental carbon, directly emitted organic 
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carbon (OC), directly emitted sulfate (SO4), directly emitted nitrate (NO3), and other inorganic 

particles (including but not limited to crustal material, metals, and sea salt).”

The PM2.5 Implementation Rule requires all states to address SO2 as a PM2.5 attainment

plan precursor and to evaluate SO2 for possible control measures in all PM2.5 nonattainment 

areas. States are also required to address NOx as a PM2.5 attainment plan precursor and evaluate 

reasonable controls for NOx in PM2.5 attainment plans, unless the state and EPA make a finding 

that NOx emissions from sources in the state do not significantly contribute to PM2.5

concentrations in the relevant nonattainment area.

Although current scientific information shows that certain VOC emissions are precursors 

to the formation of secondary organic aerosol, and significant progress has been made in 

understanding the role of gaseous organic material in the formation of organic particular matter 

(PM), this relationship remains complex. Further research and technical tools are needed to 

better characterize emissions inventories for specific VOC compounds and to determine the 

extent of the contribution of specific VOC compounds to organic PM mass. Because of these 

factors, the PM2.5 Implementation Rule did not require states to address VOCs as PM2.5

attainment plan precursors and evaluate them for control measures, unless the state or EPA 

makes a finding that VOCs significantly contribute to a PM2.5 nonattainment problem in the state 

or to other downwind air quality concerns.

The PM2.5 Implementation Rule describes the formation of particles related to NH3

emissions, which is a complex, nonlinear process. Though recent studies have improved our 

understanding of the role of NH3 in aerosol formation, ongoing research is needed to better 

describe the relationships between NH3 emissions, particulate matter concentrations, and related 

impacts. Also, area specific data is needed to evaluate the effectiveness of reducing NH3 

emissions on reducing PM2.5 concentrations in different areas, and to determine where NH3

decreases may increase the acidity of particles and precipitation. For these reasons, in the PM2.5

Implementation Rule, NH3 is presumed not to be a PM2.5 attainment plan precursor, meaning that 

the state is not required to address NH3 in its attainment plan or evaluate sources of NH3

emissions for reduction measures, unless the state or EPA makes a finding that NH3 significantly

contributes to a PM2.5 nonattainment problem in the area or to other downwind air quality

concerns.

The presumptive inclusion of NOx and the presumptive exclusion of VOC and NH3 as 

attainment plan precursors can be reversed based on an acceptable technical demonstration for a 

particular nonattainment area by the state or EPA. Such a demonstration should include 

information from multiple sources, including results of speciation data analyses, air quality

modeling studies, chemical tracer studies, emission inventories, or special intensive measurement 

studies to evaluate specific atmospheric chemistry in an area. See PM2.5 Implementation Rule for 

more information.
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The PM2.5 Implementation Rule also provided guidance on other elements of a state’s 

attainment plan, including, but not limited to, consideration of emission inventories, contingency

measures, and MVEBs used for transportation conformity purposes.

There are, however, three aspects of the PM2.5 Implementation Rule for which EPA 

received petitions requesting reconsideration. These pertain to the presumption or advance 

determination that compliance with the requirements of the Clean Air Interstate Rule (CAIR) 

automatically satisfies the requirements for RACT or RACM for NOx or SO2 emissions from 

electric generating unit (EGU) sources participating in regional cap and trade programs; the 

suggestion in the preamble that the economic feasibility element of a RACT determination for 

EGUs should include consideration of whether the cost of a measure is reasonable in light of the 

benefits; and the policy described in the preamble of allowing certain emissions reductions from 

outside the nonattainment area to be credited as meeting the RFP requirement. EPA has granted

these petitions. The attainment plan for the Delaware portion of the Philadelphia area did not 

rely on any of these aspects of the rule.

CAIR, as originally promulgated, requires significant reductions in emissions of SO2 and 

NOx to limit the interstate transport of these pollutants. In 2008, however, the D.C. Circuit 

remanded CAIR back to EPA. See North Carolina v. EPA, 550 F.3d 1176. The Court found 

CAIR to be inconsistent with the requirements of the CAA, North Carolina v. EPA, 531 F.3d 896 

(D.C. Cir. 2008), but ultimately remanded the rule to EPA without vacatur because it found that 

“allowing CAIR to remain in effect until it is replaced by a rule consistent with [the court’s] 

opinion would at least temporarily preserve the environmental values covered by CAIR,” North 

Carolina v. EPA, 550 F.3d at 1178. In response to the court’s decision, EPA has issued a new 

rule to address interstate transport of NOx and SO2 in the eastern United States (i.e., the 

Transport Rule, also known as the Cross-State Air Pollution Rule). See 76 FR 48208, August 8, 

2011. In the Transport Rule, EPA finalized regulatory changes to sunset CAIR and the CAIR 

Federal Implementation Plans (FIPs) for control periods in 2012 and beyond. See 76 FR 48322. 

On December 30, 2011, the D.C. Circuit issued an order addressing the status of the 

Transport Rule and CAIR in response to motions filed by numerous parties seeking a stay of the 

Transport Rule pending judicial review. In that order, the D.C. Circuit stayed the Transport Rule 

pending the court’s resolution of the petitions for review of that rule in EME Homer Generation, 

L.P. v. EPA (No. 11-1302 and consolidated cases). The court also indicated that EPA is 

expected to continue to administer the CAIR in the interim until the court rules on the petitions 

for review of the Transport Rule. 

Under the circumstances set forth above, EPA believes it is appropriate to finalize its 

proposed approval of the Delaware portion of the Philadelphia area attainment plan 

demonstration. Although the Court has stayed the implementation of the Transport Rule at this 

time, EPA believes that the rule has a strong legal basis. To the extent that the current status of 

CAIR and the Transport Rule affect any of the criteria for approval of this area’s attainment plan,

we believe that the ongoing implementation of CAIR during the period of the stay, coupled with 
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the promulgation of the Transport Rule, provide adequate assurance of the components of the 

attainment plan. Thus, for purposes of this proposed approval, EPA believes that the state may

rely on the combination of CAIR, which remains in place temporarily during the period of the 

stay, and the Transport Rule which has been promulgated to replace the CAIR. When the court 

issues its ruling on the merits of the Transport Rule, EPA will re-evaluate its position as 

necessary and take such further action as is appropriate.

III. Determinations of Attainment

The data in Table 1 indicates that the Delaware portion of the Philadelphia area is 

meeting the 1997 annual PM2.5 NAAQS. In addition, Table 2 shows that the Delaware portion of 

the Philadelphia area continues to attain the 1997 annual PM2.5 NAAQS by 2010. However, this 

action does not determine that the Delaware portion of the Philadelphia area has attained the 

1997 annual PM2.5 NAAQS and the information is included here only to support Delaware’s 

demonstration that the Delaware portion of the Philadelphia area could meet the attainment date 

of April 5, 2010, and continues to attain based on the most recent data available. EPA is taking 

action to formally determine the Delaware portion of the Philadelphia area’s attainment of the 

1997 annual PM2.5 NAAQS in a separate action.

Table 1. 2009 Annual Averaged PM2.5 Design Value

County Site Name Site Number Design Value (μg/m3)

New Castle Bellefonte 100031003 12.3

New Castle Lums Pond 100031007 11.4

New Castle Newark 100031012 12.5

New Castle MLK 100032004 13.3

Table 2. 2008-2010 Monitored Annual Design Values

County Site Name Site Number Design Value (μg/m3)

2008 2009 2010

New Castle Bellefonte 100031003 12.9 12.2 11.1

New Castle Lums Pond 100031007 11.8 11.3 10.5

New Castle Newark 100031012 12.9 12.2 11.2

New Castle MLK 100032004 14.2 13.0 11.7

B. COMPONENTS OF DELAWARE’S ATTAINMENT PLAN

In accordance with section 172(c) of the CAA and the PM2.5 Implementation Rule, the 

attainment plan submitted on April 3, 2008 by DNREC for the Delaware portion of the 

Philadelphia area included: (1) an emissions inventory for the plan’s base year (2002); (2) an 

attainment demonstration; and (3) MVEBs for the attainment year. The attainment 

demonstration includes: (a) technical analyses that locate, identify, and quantify sources of 
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emissions contributing to violations of the 1997 annual PM2.5 NAAQS; (b) analyses of future 

year emissions reductions and air quality improvements expected to result from national and 

local programs from new measures to meet RACM/RACT requirements; (c) adopted emission 

reduction measures with schedules for implementation; and (d) contingency measures for NOx, 

SO2 and direct PM2.5 to be implemented if the area did not meet RFP or did not attain the 

standard by the attainment date. 

On November 17, 2011, DNREC submitted a supplement to the April 3, 2008 submittal. 

This supplement submittal 1) replaces the onroad emissions budget in the April 3, 2008 submittal 

with a budget that is based on a new onroad mobile emissions model – MOVES model; 2) 

demonstrates that the MOVES based mobile source budget is consistent with attainment of the 

PM2.5 NAAQS by 2010; and 3) demonstrates that the contingency requirements of the CAA are 

met. This SIP revision only impacts PM2.5 and NOx emissions and calculations. 

To analyze future year emissions reductions and air quality improvements, Delaware used 

local, regional, and national modeling analyses that have been developed to support Federal and 

local emission reduction programs. This modeling was performed in accordance with EPA’s 

“Guidance on the Use of Models and Other Analyses for Determining Attainment of Air Quality

Goals for Ozone, PM2.5, and Regional Haze,” (EPA-454/B-07-002, April 2007). 

C. EPA’S REVIEW AND TECHNICAL INFORMATION

The following EPA analysis of the PM2.5 attainment plan for the Delaware portion of the 

Philadelphia area addresses all required elements of a PM2.5 attainment plan as described in the 

PM2.5 Implementation Rule (72 FR 20586).

 

I. Pollutants Addressed 

In accordance with policies described in the PM2.5 Implementation Rule, Delaware’s 

PM2.5 attainment plan evaluates emissions of direct PM2.5, SO2, and NOx in the Delaware portion 

of the Philadelphia area. With regard to evaluation of PM2.5 precursors, the PM2.5

Implementation Rule requires that SO2 be evaluated for controls in all nonattainment areas, and 

describes general presumptive policies for NOx, NH3, and VOCs. For NOx, states are required 

to address NOx as a PM2.5 attainment plan precursor and evaluate reasonable controls for NOx in 

PM2.5 attainment plans, unless the state makes a finding that NOx emissions in the state do not 

significantly contribute to PM2.5 concentrations in the area. For NH3, because of uncertainties 

regarding NH3 emission inventories and the efficacy of ammonia control technologies, the final 

rule sets forth the presumption that NH3 is not a PM2.5 precursor and that states are not required 

to address NH3 in their attainment plan. Similarly, VOC emissions are presumed not to be an 

attainment plan precursor because of uncertainties regarding the role of VOC in secondary

organic aerosol formation. Delaware’s attainment plan does not reverse any of these

presumptions.
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II. Emissions Inventory Requirements

Section 172(c)(3) of the CAA requires states to develop emissions inventories of point, 

area, onroad mobile, and nonroad mobile sources for their attainment demonstrations. These 

inventories provide a detailed accounting of all emissions and emissions sources by precursor or 

pollutant. In addition, inventories are used to model air quality to demonstrate that attainment of 

the 1997 PM2.5 NAAQS as expeditiously as practicable, and if an attainment extension beyond 

2010 is needed to support the need for such an extension. Emissions inventory guidance was 

provided in the April 1999 document “Emissions Inventory Guidance for Implementation of 

Ozone and Particulate Matter NAAQS and Regional Haze Regulations,” (EPA–454/R–99–006), 

which was updated in November 2005 (EPA–454/R–05–001). Emissions reporting requirements 

were provided in the 2002 Consolidated Emissions Reporting Rule (CERR) (67 FR 39602). On 

December 17, 2008 (73 FR 76539), EPA promulgated the Air Emissions Reporting 

Requirements (AERR) to update emissions reporting requirements in the CERR, and to 

harmonize, consolidate and simplify data reporting by states.

In accordance with the AERR and the November 2005 guidance, the PM2.5

Implementation Rule required states to submit inventory information on directly emitted PM2.5

and PM2.5 precursors and any additional inventory information needed to support an attainment 

demonstration.

PM2.5 is comprised of filterable and condensable emissions. Condensable particulate 

matter (CPM) can comprise a significant percentage of direct PM2.5 emissions from certain 

sources, and are required to be included in national emission inventories based on emission 

factors. Test Methods 201A and 202 are available for source-specific measurement of 

condensable emissions. However, the PM2.5 Implementation Rule acknowledged that there were 

issues and concerns related to availability and implementation of these test methods as well as 

uncertainties in existing data for condensable PM2.5. In recognition of these concerns, EPA 

established a transition period during which EPA could assess possible revisions to available test 

methods and to allow time for states to update emissions inventories as needed to address direct 

PM2.5, including condensable emissions. Because of the time required for this assessment, EPA 

recognized that states would be limited in how to effectively address CPM emissions, and 

established a period of transition, up to January 1, 2011, during which state submissions for 

PM2.5 were not required to address CPM emissions. Amendments to these test methods were 

proposed on March 25, 2009 (74 FR 12969), and finalized on December 21, 2010 (75 FR 

80118). The amendments to Method 201A added a particle-sizing device for PM2.5 sampling, 

and the amendments to Method 202 revised the sample collection and recovery procedures of the 

method to reduce the formation of reaction artifacts that could lead to inaccurate measurements 

of CPM emissions. 

The period of transition for establishing emissions limits for condensable direct PM2.5

ended on January 1, 2011. PM2.5 submissions made during the transition period are not required 

to address CPM emissions; however, states must address the control of direct PM2.5 emissions, 
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including condensable emissions, with any new action taken after this January 1, 2011. 

Delaware submitted the Delaware portion of the Philadelphia area attainment plan prior to 

January 1, 2011 and did not consider condensables. 

In July 2008, EarthJustice filed a petition requesting reconsideration of EPA’s transition 

period for CPM emissions provided in the PM2.5 Implementation Rule. In January 2009, EPA 

decided to allow states that have not previously addressed CPM to continue to exclude CPM for 

PSD permitting during the transition period. This TSD reflects a review of Delaware’s submittal 

based on current EPA guidance as described in the PM2.5 Implementation Rule. More 

information and the review and evaluation of the methods used for the emissions inventory

submitted by Delaware are found in section 3 of Delaware’s attainment plan submittal and a TSD

entitled, “Technical Support Document for Emissions Inventories for the Delaware

Nonattainment Area PM2.5 SIP Base Year Inventory,” dated June 16, 2010.

1. 2002 Base Year Emission Inventories

An emission inventory is an estimate of the emissions from sources in a particular area. 

DNREC developed an emission inventory for 2002, which is the base year for attainment 

planning purposes with respect to 8-hour ozone and PM2.5 SIPs and for planning purposes with 

respect to the regional haze SIPs. The 2002 base year inventory includes the pollutants PM10, 

PM2.5, SO2, NOx, VOC, and NH3. The inventory consists of four sectors: stationary point 

sources, stationary area sources, highway vehicle sources and nonroad sources. The MidAtlantic/Northeast Visibility Union (MANE-VU) compiled a regional inventory from the 

emission inventories of the Northeastern and Mid-Atlantic states. This regional inventory was 

used to perform the regional modeling analysis used in the Delaware’s air quality management 

effort to attain the 8-hour ozone NAAQS and the PM2.5 NAAQS, and to prepare the regional haze 

plan.

Stationary point source inventory represents facility-specific data for Delaware’s larger 

stationary sources. Point sources typically include large industrial, commercial and institutional 

facilities. Manufacturing facilities, within the industrial sector, comprise the majority of all 

reporting point sources. The institutional sector includes hospitals, universities, prisons, military

bases, landfills and wastewater treatment plants. Point source emissions data are submitted to 

Air Quality Management Section (AQMS) by the facilities using Terminal Server Satellite iSTEPS software. i-STEPS are the point source emission inventory electronic data management 

system.

Area sources represent a large and diverse set of individual emission source categories. 

An area source category is either represented by small facilities too numerous to individually

inventories, such as restaurants (commercial cooking), or is a common activity, such as fugitive 

dust from construction and agricultural production. Emissions from area sources were estimated 

at the county level. For the area sources, DNREC provided an inventory that contained 
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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). Area 

source estimates were provided by source classification code (SCC).

Highway vehicles, which include passenger cars and light-duty trucks, other trucks, 

buses, and motorcycles, are onroad mobile source emissions inventory that was developed using 

the most current version of EPA’s highway mobile source emissions model MOBILE6.2 and 

link-level vehicle miles traveled (VMT) data for each county from the Delaware Department of 

Transportation (DelDOT). The emission factors developed using MOBILE6.2, 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.

Nonroad sources, which encompass a diverse collection of engines, including, but not 

limited to, outdoor power equipment, recreational vehicles, farm and construction machinery, 

lawn and garden equipment, industrial equipment, recreational marine vessels, commercial 

marine vessels, locomotives, ships, and aircraft were estimated using the EPA NONROAD 2005 

model.

The emissions inventory for the base year, 2002, was developed in accordance with EPA 

guidance, “Emissions Inventory Guidance for Implementation of Ozone and Particulate Matter 

National Ambient Air Quality Standards and Regional Haze Regulations, EPA-454/R-05-001, 

August 2005, updated November 2005.” Tables 3, 4 and 5 summarize the emissions for 2002.

Table 3. 2002 Annual Emissions by County (tpy)

County PM10 PM2.5 SO2 NOx NH3 VOC

Kent 3991 1097 4062 10314 2841 5296

New Castle 8604 3430 50237 30748 1384 18062

Sussex 6758 2575 25552 16060 10057 10251

Total 19353 7102 79852 57122 14284 33610

Table 4. 2002 Statewide Annual Emissions (tpy)

Source Sector PM10 PM2.5 SO2 NOx NH3 VOC

Point 3859 3161 73708 16372 179 4773

Area 13870 2580 1330 2427 13194 10254

Onroad 581 415 584 21341 903 10564

Nonroad 1043 946 4230 16982 8 8019

Total 19353 7102 79852 57122 14284 33610
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Table 5. 2002 New Castle County Annual Emissions (tpy)

Source Sector PM10 PM2.5 SO2 NOx NH3 VOC

Point 2168 1733 47070 9157 118 2687

Area 5674 1073 780 1513 710 6198

Onroad 304 209 326 11799 552 5762

Nonroad 458 415 2061 8279 4 3415

Total 8604 3430 50237 30748 1384 18062

The review and evaluation of the methods used for the emissions inventory submitted by

Delaware are found in the attainment plan submittal (section 3) and a TSD entitled “Technical 

Support Document for Emissions Inventories for the Delaware Nonattainment Area PM2.5 SIP

Base Year Inventory,” dated June 16, 2010.

2. 2009 Projected Emission Inventories

Tables 6 and 7 summarize the emissions expected in 2009. These emissions take activity

and emissions growth and/or controls from 2002 into account. Section 4 and Appendix 4-3 of 

the Delaware’s attainment plan, relating to emissions projections, contains documents that 

describe the methodologies used to project the 2002 baseline emissions to 2009.

Table 6. 2009 Projected Emissions (tpy), i.e., Control Strategy Emissions

County NH3 NOx PM10 PM2.5 SO2 VOC

Kent 2887 7799 3253 989 3664 4230

New Castle 1466 21807 6039 3015 14135 13887

Sussex 10106 11591 5731 2571 11724 7558

Totals 14459 41197 15023 6575 29523 25675

Table 7. CMAQ Modeled 2009 Emissions (tpy), i.e., Attainment Targets

County NH3 NOx PM10 PM2.5 SO2 VOC

Kent 2887 7799 3253 989 3664 4230

New Castle 1466 21807 6039 3015 14135 13887

Sussex 10106 11591 5731 2571 11724 7558

Totals 14459 41197 15023 6575 29523 25675

3. Growth Projections Methodologies

Growth projections methodologies describe the data, methods and assumptions utilize in 

developing estimates of emissions changes between 2002 and the milestone year 2009. 

Appendix 4-1 of the Delaware’s attainment plan contains the technical support document 

entitled, “Development of Emission Projections for 2009, 2012, and 2018 for Non-EGU Point, 

Area, and Nonroad Sources in the MANE-VU Region,” developed by MARAMA. This
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document provides detail on the specific factors, control assumptions, and implementation 

schedules used in the emission projection calculations for each source category.

III. Modeling

All attainment demonstrations must include modeling that is performed in accordance 

with EPA’s “Guidance on the Use of Models and Other Analyses for Demonstrating Attainment 

of Air Quality Goals for Ozone, PM2.5, and Regional Haze” (EPA-454/B-07-002, April 2007). 

Modeling may be based on national (e.g., EPA), regional (e.g., Ozone Transport Commission), 

local modeling, or a combination thereof, if appropriate. A description of modeling used to 

support Delaware’s attainment demonstration follows. More detailed information on the 

modeling is discussed in a TSD entitled, “Technical Support Document for the Modeling and 

Weight of Evidence Portions of the Delaware’s State Implementation Plan for Attainment of the 

PM2.5 Annual NAAQS,” dated June 15, 2010 and section 6 of the Delaware’s attainment plan.

Conceptual Model Description

A conceptual model describes how weather patterns affect the formation and transport of 

PM2.5, accounting for emissions and photochemistry.

The conceptual model for Delaware’s attainment plan is described in a document 

prepared by the Northeast States for Coordinated Air-Use Management (NESCAUM) final report 

entitled, “The Nature of the Fine Particle and Regional Haze Air Quality Problems in the 

MANE-VU Region: A Conceptual Description (2006),” for the use by the Ozone Transport 

Commission (OTC) member states which provides the conceptual description of PM2.5 issues in 

the OTC states and is consistent with EPA’s guidance.

The NESCAUM document contains a conceptual description that explains how elevated 

regional PM2.5 peak concentrations in the summer differ significantly from the largely urban peak 

concentrations observed during winter. On average, summertime concentrations of sulfate in the 

northeastern United States are more than twice that of the next most important fine particle 

constituent, organic carbon (OC), and more than four times the combined concentration of nitrate 

and black carbon (BC) constituents. Episodes of high summertime sulfate concentrations are 

consistent with stagnant meteorological flow conditions upwind of the Delaware portion of the 

Philadelphia area and the accumulation of airborne sulfate (via atmospheric oxidation of SO2) 

followed by long-range transport of sulfur emissions from industrialized areas within and outside 

the area. National assessments have indicated that in the winter, sulfate levels in urban areas are 

higher than background sulfate levels across the eastern U.S., indicating that the local urban 

contribution to wintertime sulfate levels is significant relative to the regional sulfate contribution 

from long-range transport. A network analysis for the winter of 2002 suggests that the local 

enhancement of sulfate in urban areas of the MANE-VU region ranges from 25 to 40% and that 
13

the long-range transport component of PM2.5 sulfate is still the dominant contributor in most 

eastern cities.

In the winter, urban OC and sulfate each account for about a third of the overall PM2.5 

mass concentration observed in Philadelphia and New York City areas. Nitrate also makes a 

significant contribution to urban PM2.5 levels observed in the northeastern United States during 

the winter months. Wintertime concentrations of OC and nitrate in urban areas can be twice the 

average regional concentrations of these pollutants, indicating the importance of local source 

contributions. This is likely because winter conditions are more conducive to the formation of 

local inversion layers which prevent vertical mixing. Under these conditions, emissions from 

tailpipe, industrial and other local sources become concentrated near the Earth’s surface, adding 

to background pollution levels associated with regionally transported emissions. 

The Model Used in the Attainment Demonstration 

By agreement of OTC, the New York State Department of Environmental Conservation 

(NYSDEC) ran the Community Multi-scale Air Quality Model (CMAQ) for the states in the 

northeast ozone transport region that includes Delaware. EPA agrees CMAQ is appropriate for 

this modeling demonstration. The inputs to the model are described in section 6 of the 

attainment plan submittal. 

Meteorological Time Periods Used in the Modeling

Since the Delaware portion of the Philadelphia area’s attainment demonstration used a 

resource intensive photochemical grid model, EPA accepts the use of single, recent 

representative year to be used for an annual simulation. Two factors were used in selecting 2002 

as the representative year: the observed annual mean concentrations of PM2.5 are close to the 

3-year observed design value at all, or most monitoring sites, and the pattern of quarterly mean 

values is similar to the pattern of quarterly mean concentrations averaged over 3 years.

Meteorological Data Used in the Air Quality Model 

The OTC modeling committee decided to use a prognostic meteorological model that 

provides life-like meteorological inputs to the photochemical grid model. The Pennsylvania 

State University/National Center for Atmospheric Research Mesoscale Meteorological Model 

(MM5) version 3.6 was chosen for the modeling analysis. The MM5 model provides a 

reasonable representation of weather conditions at the surface and aloft. 
14

Domain of the Model, Horizontal/Vertical Resolution and the Initial and Boundary 

Conditions 

The modeling domain extends from Maine to Florida and out in the Atlantic Ocean on the 

east and west to the Mississippi River. The size of the modeling domain was made large enough 

to include all emission sources that affect PM2.5 concentration in the northeastern United States. 

Even this boundary is defined by a larger photochemical modeling domain that covers much of 

North America. Over the northeastern United States, the model used 12 kilometer grid cells. 

The Philadelphia area is included in the 12 kilometer grid cell area. The OTC Modeling 

Committee used a 12-kilometer grid size for the areas in and near its states to provide a fine 

enough grid resolution to adequately capture the PM patterns experienced in the ozone transport 

region (OTR). Outside the local areas the grid resolution used in the modeling is 36 kilometers. 

The selection of model domains and horizontal grid resolution was deemed acceptable to EPA.

Vertical resolution is the number of layers and the size of each layer in the model. The 

layers in the photochemical grid model were set up to be compatible with the model that 

produced weather conditions for the photochemical grid model. The vertical resolution used in 

the modeling exercise followed EPA’s modeling guidance and therefore adequately represents 

the atmosphere where PM2.5 is emitted, forms and is transported. 

Emissions Used in the Air Quality Model 

The emissions data for 2002 were generated by individual states within the OTR and 

assembled and processed through MANE-VU, a Regional Planning Organization (RPO). These 

emissions were then processed by NYSDEC using the sparse matrix operator kernel emissions 

(SMOKE) emissions processor to provide CMAQ compatible inputs. The 2002 emissions for 

the non-OTR areas within the modeling domain were obtained from the corresponding RPOs and 

were processed using SMOKE, in manner similar to that of the OTR emissions. The OTR states, 

through MANE-VU, contracted MACTEC Federal Programs (called Contractor) to develop 

2009, 2012, and 2018 inventories based on 2002 inventories that the states had previously

developed for the base-year model work. The Contractor, in consultation with the states, 

developed the necessary growth and control factors and applied to the 2002 inventory. 

Base Case Run Model Performance Evaluation 

NYSDEC performed a model evaluation for the OTC to determine how well CMAQ 

reproduced the 2002 PM2.5 concentrations. CMAQ was employed to simulate PM2.5 for the 

calendar year 2002. A review of PM2.5 and its individual species was conducted for the study

domain. Several observations were made with respect to model performance: 1) approximately

80 – 90 percent of organic mass (OM) is in the primary fraction; 2) CMAQ captures seasonal 

variation in SO4 well; 3) CMAQ appears to overestimate primary PM2.5 components, especially
15

during colder months; and 4) CMAQ appears to underestimate secondary OM during the 

summer.

These issues are not of great regulatory concern since attainment tests are based on the 

application of relative response factors. Therefore, the regional and local model performance is 

acceptable for PM2.5. While there are some differences between the spatial data between subregions, there is nothing to suggest a tendency for the model to respond in a systematically

different manner between regions. Examination of the statistical metrics by sub-region confirms 

the absence of significant performance problems arising in one area but not in another, building 

confidence that the CMAQ modeling system is operating consistently across the full OTC 

domain. This confidence in the modeling results allows for the modeling system to be used to 

support the attainment plan to meet the 1997 annual PM2.5 NAAQS.

2009 Control Case Modeling and Modeled Attainment Test 

As previously mentioned, the Delaware portion of the Philadelphia area has an attainment 

date of April 5, 2010. The PM2.5 NAAQS include an annual standard of 15 μg/m3based on the 

3-year average of annual mean PM2.5 concentrations.

The purpose of a modeling assessment is to determine if control strategies currently being 

implemented (“on the books”) will lead to attainment of the annual average NAAQS for PM2.5 by

2009. The modeling is applied in a relative sense, similar to the 8-hour ozone attainment test. 

However, the PM2.5 attainment test is more complicated and reflects the fact that PM2.5 is a 

mixture. In the test, ambient PM2.5 is divided into major components, with a separate relative 

response factor (RRF) and future design value (DVF) calculated for each of the PM2.5 

components. Since the attainment test is calculated on a per species basis, the attainment test for 

PM2.5 is referred to as the Speciated Modeled Attainment Test (SMAT).

Annual SMAT Results

Table 8 presents the results of the annual SMAT results for the Philadelphia area. The 

SMAT results demonstrate that the projected average annual arithmetic mean PM2.5

concentration calculated at each Federal Reference Method (FRM) monitor attains the annual 

PM2.5 NAAQS. Specifically, all calculations are less than15 μg/m3. Table 8 presents the results 

of the annual SMAT results for a suite of regional modeling runs conducted by OTC each 

representing OTB/OTW – “On the Books, On the Way” control measures. All runs demonstrate 

compliance with the annual PM2.5 NAAQS.
16

Table 8. Annual SMAT Results for Philadelphia-Wilmington, PA-NJ-DE PM2.5

Nonattainment Area On-The-Books-On-The-Way Control Measures

In summary, the basic photochemical grid modeling, presented in the Delaware’s

attainment plan, used the methods recommended in EPA’s modeling guidance. When EPA’s 

attainment test is applied to the modeling results, the 2009 annual-average PM2.5 design value is 

predicted to be 13.3 μg/m3 in the Philadelphia area. Therefore, based on EPA’s modeled 

attainment test, the Philadelphia area reached attainment of the annual average PM2.5 standard in 

2009 before the attainment date of April 5, 2010. 

Supplemental Analyses and Weight of Evidence (WOE) Determination

EPA’s modeling guidance states that additional analyses are recommended to determine 

if attainment will be likely, even if the modeled attainment test is “passed.” The guidance 

recommends supplementary analyses in all cases. EPA’s modeling guidance describes how to 

use a photochemical grid model and additional analytical methods to complete a WOE analysis 

to estimate if emissions control strategies will lead to attainment. A WOE analysis is a 

supporting analysis that helps to determine if the results of the photochemical modeling system 

are correctly (or not correctly) predicting future air quality. 

All models, including the CMAQ, model have inherent uncertainties. Over or under 

prediction may result from uncertainties associated with emission inventories, meteorological 

data, and representation of PM2.5 chemistry in the model. Therefore, EPA modeling guidance 

provides for other evidence to address these model uncertainties so that proper assessment of the 

AIRS ID

Site 

Name County State

2000-2004 Baseline Design Value 2009

Q1 Q2 Q3 Q4 DVF

420170012 Bristol Bucks PA 14.14 13.69 14.73 13.85 12.1

420290100 New Garden Chester PA 14.39 14.73 16.36 13.76 12.4

420450002 Chester Delaware PA 15.07 15.96 16.34 13.74 13.3

420910013 Norristown Montgomery PA 12.68 13.62 13.96 12.34 11.3

421010004 AMS Lab Philadelphia PA 15.99 14.01 15.95 13.82 12.9

421010024 NE Airport Philadelphia PA 13.58 13.63 14.95 12.96 11.9

421010047 Broad Street Philadelphia PA 16.59 16.45 15.80 15.37 13.5

421010136 Elmwood Philadelphia PA 15.70 14.20 15.27 12.99 12.7

100031003 Bellefonte New Castle DE 14.87 15.16 15.50 13.13 12.6

100031007 Lums Pond New Castle DE 13.16 14.37 16.05 10.66 11.3

100031012 Newark New Castle DE 15.27 14.91 16.53 13.14 12.6

100032004 MLK New Castle DE 16.41 15.40 17.61 14.04 13.3

340070003 Camden Camden NJ 13.99 14.54 15.76 12.47 12.3

340071007 Pennsauken Camden NJ 13.99 14.00 14.75 13.59 12.3

40155001 Gibbstown Gloucester NJ 13.92 13.43 15.08 11.39 11.7
17

probability to attain the applicable standards can be made. EPA modeling guidance states that 

those modeling analyses that show that attainment with the NAAQS will be reached in the future 

with some margin of safety (i.e., estimated concentrations below 14.5 μg/m3for annual PM2.5 and 

62 μg/m3for 24-hour PM2.5) need more limited supporting material. 

Due to the fact that the modeling results presented in Table 8, fall below the 

aforementioned “weight of evidence” thresholds established by EPA, a limited supplemental 

analysis was deemed necessary to support the 2009 attainment demonstration. DNREC’s 

supporting evidence includes a brief summary of the modeling demonstration, recent trends in 

the Philadelphia area’s monitoring data and a brief analysis of some of the largest SO2 sources 

within the nonattainment area (section 6 of Delaware’s attainment plan). 

IV. Reasonably Available Control Measures/Reasonably Available Control Technology

1. Requirements for RACM/RACT

CAA section 172(c)(1) requires that each attainment plan “provide for the 

implementation of all RACM as expeditiously as practicable, including such reductions in 

emissions from the existing sources in the area as may be obtained through the adoption, at a 

minimum, of RACT, and shall provide for attainment of the national primary ambient air quality

standards.” EPA interprets RACM including RACT under section 172 as measures that a state 

finds are both reasonably available and contribute to attainment as expeditiously are practicable 

in the nonattainment area. Thus, what constitutes RACM or RACT in a PM2.5 nonattainment 

area is closely tied to the expeditious attainment demonstration of the plan (40 CFR 51.1010; 

72 FR 20586 at 20612). 

States are required to evaluate RACM/RACT for direct PM2.5 emissions and all of the 

area’s attainment plan precursors (40 CFR 51.1002(c); 72 FR 20586 at 20589 – 97). Consistent 

with the guidance provided for the PM2.5 Implementation Rule, a state initially must evaluate 

RACM/RACT for sources that emit direct PM2.5, SO2, and NOx. A state may establish with an 

appropriate demonstration that it should not regulate NOx in the specific nonattainment area, so 

it could thereby forgo evaluation of RACM/RACT for NOx. Because EPA concluded that VOC 

and NH3 are presumptively not regulatory precursors for PM2.5, unless the state or EPA 

determines that it is necessary to regulate them in a specific nonattainment area, the state is not 

required to evaluate RACM/RACT for sources of VOC or NH3 unless there is a determination 

supported by an appropriate demonstration that such emissions need to be regulated for 

expeditious attainment of the NAAQS in the specific area.

For PM2.5 attainment plans, the PM2.5 Implementation Rule requires a combined approach 

to RACM and RACT under subpart 1 of part D of the CAA. Subpart 1, unlike subparts 2 and 4, 

does not identify specific source categories for which EPA must issue control technique 

documents or guidelines, or identify specific source categories for state and EPA evaluation 
18

during attainment plan development (72 FR 20586 at 20610). Rather, under subpart 1, EPA 

considers RACT to be part of an area’s overall RACM obligation consistent with the section 172 

definition. Because of the variable nature of the PM2.5 problem in different nonattainment areas 

which may require states to develop attainment plans that address widely disparate 

circumstances, EPA determined not only that states should have flexibility with respect to 

RACM/RACT controls but also that in areas needing significant emission reductions, 

RACM/RACT controls on smaller sources may be necessary to reach attainment as expeditiously

as practicable (72 FR 20586 at 20612, 20615). Thus, under the PM2.5 Implementation Rule, 

RACM and RACT are those reasonably available measures that contribute to attainment as 

expeditiously as practicable in the specific nonattainment area (40 CFR 51.1010; 72 FR 20586 at 

20612).

Specifically, the PM2.5 Implementation Rule requires that attainment plans include the list 

of measures that a state considered and information sufficient to show that the state met all 

requirements for the determination of what constitutes RACM/RACT in a specific nonattainment 

area (40 CFR 51.1010(a)). In addition, the PM2.5 Implementation Rule requires that the state, in 

determining whether a particular emissions reduction measure or set of measures must be 

adopted as RACM/RACT, consider the cumulative impact of implementing the available 

measures and to adopt as RACM/RACT any potential measures that are reasonably available 

considering technological and economic feasibility if, considered collectively, they would 

advance the attainment date by one year or more. If a measure or measures is not necessary for 

expeditious attainment of the NAAQS in the area, then by definition that measure is not 

RACM/RACT for purposes of the 1997 PM2.5 NAAQS in that area. Any measures that are 

necessary to meet these requirements which are not already either Federally promulgated, part of 

the state’s SIP, or otherwise creditable in SIPs must be submitted in enforceable form as part of a 

state’s attainment plan for the area (72 FR 20586 at 20614). 

Guidance provided in the PM2.5 Implementation Rule for evaluating RACM/RACT level 

controls for an area also indicated that there could be flexibility with respect to those areas that 

were predicted to attain the 1997 PM2.5 NAAQS within five years of designation as a result of 

existing national or local measures (72 FR 20586 at 20612). In such circumstances, EPA 

indicated that the state may conduct a more limited RACM/RACT analysis that does not involve 

additional air quality modeling. Moreover, the RACM/RACT analysis for such area would focus 

on a review of reasonably available measures, the estimation of potential emissions reductions, 

and the evaluation of the time needed to implement the measures. Thus, the PM2.5

Implementation Rule guidance recommended that not all areas would need to conduct as rigorous 

an analysis, and suggested that a less rigorous analysis would be needed for those areas expected 

to attain within the initial five years from designation as a nonattainment area for the 1997 PM2.5

NAAQS. A more comprehensive discussion of the RACM/RACT requirement for PM2.5

attainment plans and EPA’s guidance for it can be found in the PM2.5 Implementation Rule 

preamble (72 FR 20586 at 20609 – 20633).
19

2. Delaware’s Analysis of Pollutants and Sources Delaware Portion of the Philadelphia 

Area.

Based upon the emissions inventory for the area, Delaware determined that it would be 

appropriate to evaluate sources of PM2.5, SO2, and NOx located in the nonattainment area for 

potential control as RACM/RACT. Delaware did not determine that controls of sources of VOC 

or NH3 would be necessary for expeditious attainment of the NAAQS in this area, nor does EPA 

believe that there is a need to do so. Delaware’s determination with respect to which pollutants 

the plan should evaluate is at section 1.4 of the attainment plan submittal.

After evaluating which pollutants should be addressed in the attainment plan, Delaware

identified all source categories of those emissions located within the nonattainment area to 

determine available controls that could bring the area into attainment as expeditiously as possible

(section 7 of the attainment plan submittal). For the primary PM2.5 RACM, DNREC evaluated 

measures that are limited to the boundaries of the nonattainment area, i.e. New Castle County. 

However, because SO2 and NOx can be transported over considerable distances to form PM2.5, 

they were assessed on a statewide basis (Appendix 7-1 of Delaware’s attainment plan for “EPA’s 

List of Potential Control Measures”). Although VOC is not a regulated PM2.5 precursor for the 

Delaware portion of the Philadelphia area, VOC control measures approved by EPA were 

included in the modeling associated with this attainment plan. 

In accordance with 40 CFR 51.1010, a SIP revision for a PM2.5 nonattainment area is 

required to demonstrate that all RACM, including RACT stationary sources necessary to 

demonstrate attainment as expeditiously as practicable have been adopted. The cumulative 

impact of implementing available measures must be considered in determining whether a 

particular emission reduction measure or set of measures is required to be adopted as RACM. 

Potential measures that are reasonably available considering technical and economic feasibility

must be adopted as RACM if, considered collectively, they would advance the attainment date by

one year or more. Since the Delaware portion of the Philadelphia area attained at the end of 

2009, any RACM measures need to be in effect in 2008. Delaware determined that there are no 

additional control measures that could be adopted by January 1, 2008. In addition, existing 

measures and measures planned for implementation by 2009 enabled the Delaware portion of the 

Philadelphia area to attain the 1997 PM2.5 NAAQS. Therefore, no further actions on RACM or 

RACT are warranted.

3. Delaware’s evaluation of RACM/RACT control measures for the Delaware Portion of 

the Philadelphia Area.

In accordance with section 172 of the CAA, the Delaware portion of the Philadelphia area 

has adopted all RACM, including RACT, needed to attain the standards “as expeditiously as 

practicable.” Delaware’s demonstration for attaining the 1997 annual PM2.5 NAAQS in the 

Delaware portion of the Philadelphia area is based on enforceable measures.
20

a. STATIONARY POINT SOURCES

- Consent Decree, Premcor Refinery in New Castle County – control of SO2 and NOx 

emissions from boilers and heaters

- Regulation 1146 – Electric Generating Unit Multi-Pollutant Regulation – SO2 and NOx 

emission control

- Regulation 1148 – Control of Stationary Combustion Turbine Electric Generating Unit 

Emissions – NOx emission control

- Regulation 1144 – Control of Stationary Generator Emissions – SO2, PM, VOC and NOx 

emission control

- Regulation 1142 – Section 1 – Control of NOx Emissions from Industrial Boilers

- Regulation 1142 – Section 2 – Control of NOx Emissions from Industrial Boilers and 

Process Heaters at Petroleum Refineries in New Castle County

- Regulation 24 – Section 46 – Crude Oil Lightering Operations – VOC emission control

- Facility and unit shutdowns

b. AREA SOURCES 

- Regulation 24 – Section 33 – Solvent Cleaning and Drying, VOC emission control

- Regulation 24 – Section 11 – Mobile Equipment Repair and Refinishing, VOC emission 

control

- Regulation 41 – Section 3 – Portable Fuel Containers, VOC emission control

- Regulation 41 – Section 3 – Consumer Products, VOC emission control

- Regulation 41 – Section 1 – Architectural and Industrial Maintenance Coatings, VOC 

emission control

- Regulation 24 – Section 36 – Stage II Vapor Recovery, VOC emission control

- Residential Woodstoves, 40 CFR Part 60 Subpart AAA – New Source Performance 

Standards (NSPS) for PM, VOC and NOx emission control
21

- Regulation 1113 – Open Burning – PM, VOC and NOx control

c. HIGHWAY VEHICLES

- Regulation 31 – Low Enhanced inspection and Maintenance Program

- Regulation 1132 – Transportation Conformity Regulation

- 40 CFR Parts 80, 85 and 86 – Control of Air Pollution from New Motor Vehicles – Tier 2 

Motor Vehicle Emissions Standards and Gasoline Sulfur Control Requirements

- 40 CFR Parts 69, 85 and 86 – Control of Air Pollution from New Motor Vehicles –

Heavy- Duty Engines and Vehicle Standards and Highway Diesel Fuel Sulfur Control

Requirements 

- Regulation 1145 – Excessive Idling of Heavy Duty Vehicles

- Regulation 40 – National Low Emission Vehicle (NLEV) Program

d. NONROAD SOURCES

- Phase I and Phase II Emissions Standards for Gasoline-Powered Nonroad Utility Engines, 

Federal Rule

- Emissions Standards for Diesel-Powered Nonroad Utility Engines of 50 or More 

Horsepower, Federal Rule

- Emissions Standards for Spark Ignition (SI) Marine Engines, Federal Rule

- Emissions Standards for Large Spark Ignition Engines, Federal Rule

- Reformulated Gasoline Use in Nonroad Motor Vehicles and Equipment, Federal Rule

e. OTHER MEASURES

- Regulation 1124 – Section 36 – Mandatory episodic prohibition of lightering on ozone 

action days

- Regulations 1146 and 1148 – Reduction of emissions from high electric demand day

electric generations
22

- Voluntary measures effective in 2010 include: Brandywine School District bus retrofits;

Delaware ride share; ozone action days; use biodiesel in state-run equipment; best 

workplaces for commuters and SmartWay transport programs; implement an anti-idling 

outreach programs for school and school districts; clean state program; installation of 

E85 station; and continue to identify and implement efficiency programs for the 

residential and commercial sectors.

4. RACM/RACT Demonstration and Control Strategy

Delaware’s evaluation of RACM/RACT control measures for the Delaware portion of the 

Philadelphia area is approvable. The most current monitoring data for this area indicates that it is 

attaining the 1997 PM2.5 NAAQS. EPA’s guidance for the PM2.5 Implementation Rule 

recommended that if an area was predicted through the attainment plan to attain the standards 

within five years after designation, then the state could submit a more limited RACM/RACT 

analysis and the state could elect not to do additional modeling. 

In light of the fact that the Delaware portion of the Philadelphia area is now attaining the 

standards, the attainment plan meets the RACM/RACT requirements of the PM2.5

Implementation Rule, and that the level of control in Delaware’s attainment plan constitutes 

RACM/RACT for purposes of the 1997 PM2.5 NAAQS. Because the PM2.5 Implementation Rule 

defines RACM/RACT as that level of control that is necessary to bring the area into attainment, 

the current level of federally enforceable controls on sources located within the Philadelphia area 

is by definition RACM/RACT for this area for this purpose. 

V. Reasonable Further Progress

Section 172(c)(2) of the CAA requires that attainment plans include RFP to achieve 

steady progress toward meeting air quality standards by showing generally linear progress toward 

attainment. The PM2.5 Implementation Rule set forth that an area that demonstrates attainment 

by 2010 will be considered to have satisfied the RFP requirement and need not submit any

additional material to satisfy the RFP requirement. EPA views the attainment demonstration as 

also demonstrating that the area is making reasonable further progress toward attainment. A state 

is required to submit a separate RFP plan for any area for which the state seeks an extension of 

the attainment date beyond 2010. The RFP plan is required to provide emission reductions such 

that emissions in 2009 represent generally linear progress from the 2002 baseline year to the

attainment year. The Delaware portion of the Philadelphia area attained by 2010, and has 

therefore met the RFP requirements. For similar reasons, such areas are not subject to a 

requirement for a mid-course review.
23

VI. Contingency Measures

In accordance with section 172(c)(9) of the CAA, the PM2.5 Implementation Rule requires 

that PM2.5 attainment demonstrations include contingency measures (40 CFR 51.1012 and 72 FR 

at 20642 – 20646, April 25, 2007). Contingency measures are additional measures to be

implemented in the event that an area fails to meet RFP or fails to attain a standard by its 

attainment date. These measures must be fully adopted rules or control measures that can be 

implemented quickly and without significant further EPA or state action if the area fails to meet 

RFP or fails to attain by its attainment date, and should contain trigger mechanisms and an 

implementation schedule. In addition, they should be measures not already included in the SIP 

control strategy and should provide for emission reductions equivalent to one year of RFP. 

Delaware submitted contingency measures as required by the PM2.5 Implementation Rule, 

composed of: electric generating unit multi-pollutant regulation controlling NOx and SO2

emissions; and a consent decree with Premcor Refinery controlling NOx emissions from boilers 

and heaters. In accordance with section 110(k)(2) of the CAA, EPA must take action on the 

contingency measures that were submitted by Delaware. However, as noted in section A.III. of 

this document, the Delaware portion of the Philadelphia area, which consists of New Castle 

County, has attained the 1997 annual PM2.5 NAAQS, meets the attainment date of April 5, 2010, 

and continues to attain based on the most recent data available. Because EPA has determined 

that the area attained by its required attainment date, in accordance with section 179(c)(9), no 

contingency measures for failure to attain by this date need be implemented, and further EPA 

action is unnecessary. Furthermore, as set forth in the PM2.5 Implementation Rule, areas that 

attained the NAAQS by the attainment date are considered to have satisfied the requirement to 

show RFP, and as such do not need to implement contingency measures to make further progress 

to attainment. EPA has determined that the area has attained by the attainment date, therefore the 

contingency measures submitted by Delaware are no longer necessary for the Delaware portion 

of the Philadelphia area to meet RFP requirements or attain the annual PM2.5 NAAQS by the 

attainment date.

The PM2.5 Implementation Rule requires that quantity of emission reductions needed to 

satisfy contingency requirements is an amount equal to one’s year worth of required reductions. 

Required reductions are the amount of reductions needed to attain compliance with the PM2.5

NAAQS. 2002 emissions are the base year emissions and the CMAQ modeled 2009 emissions 

are the emission levels necessary for attainment. Therefore, the difference between these 

emission levels is the total quantity of reductions required for attainment. Since there are seven 

years between 2002 and 2009, the total quantity of reductions required for attainment is divided 

by seven to determine one-year’s worth of required reductions (i.e., the contingency

requirement).

Table 9 displays the 2002 base year emissions and the 2009 emission reductions (i.e., 

attainment targets) accounted for in the CMAQ model which showed attainment in 2010 for the 

Philadelphia area. 
24

Table 9. 2002 Base Year and CMAQ Modeled 2009 Emissions (tpy)

Year County NOx PM2.5 SO2 

2002 New Castle 30748 3430 50237

2009 New Castle 23048 3249 12001

Table 10 shows one year’s worth of required emission reductions (i.e., the amount require 

for contingency). This was calculated by subtracting the attainment targets from the 2002 base 

year and dividing the difference by 7 years.

Table 10. Contingency Requirement (tpy)

County NOx PM2.5 SO2 

New Castle 1100 26 5462

Table 11 shows that Delaware has met the contingency requirements relative to the 

pollutants NOx and PM2.5, since the projected 2009 emission levels are lower than those needed 

for attainment by at least the amount of the contingency requirement.

Table 11. Calculation of Required Contingency Plan Reductions

New Castle County NOx (tpy) PM2.5 (tpy)

Target Reductions for Attainment 23048 3249

Calculated Excess Reductions 1241 234

Contingency Requirement 1100 26

Excess Reductions Satisfy Contingency

Requirement

Yes Yes

VIII. Motor Vehicle Emission Budgets

Section 176(c) of the CAA requires Federal actions in nonattainment and maintenance 

areas to “conform to” the goals of SIPs. This means that such actions will not cause or contribute

to violations of a NAAQS, worsen the severity of an existing violation, or delay timely

attainment of any NAAQS or any interim milestone. Actions involving Federal Highway

Administration (FHWA) or Federal Transit Administration (FTA) funding or approval are 

subject to the transportation conformity rule (40 CFR 93, subpart A). Under this rule, 

metropolitan planning organizations (MPOs) in nonattainment and maintenance areas coordinate 

with State Air Quality and Transportation Agencies, EPA, and the FHWA and FTA to 

demonstrate that their long range transportation plans (“plans”) and transportation improvement 

programs (TIP) conform to applicable SIPs. This is typically determined by showing that 

estimated emissions from existing and planned highway and transit projects are less than or equal 

to the MVEBs contained in the SIP.
25

The MVEBs for the 2009 attainment year are based on the projected 2009 onroad motor 

vehicle source emissions, accounting for the emission reductions from on-road vehicle source 

control measures, including transportation control measures and vehicle technology, fuel or 

maintenance-based measures. MVEBs for 2009 attainment year for the Delaware portion of the 

Philadelphia area, submitted on April 3. 2008 were 87 tpy for PM2.5-direct and 4,904 tpy for 

NOx. More detailed information can be found in the TSD entitled, “Adequacy Findings for 

Motor Vehicle Emissions Budgets in the 2009 Attainment Plan for the Delaware Portion of the 

Philadelphia 1997 PM2.5 NAAQS Nonattainment Area,” January 7, 2010.

The budgets that Delaware submitted on April 3, 2008 were calculated using the 

MOBILE6.2 motor vehicle emissions model because this model was the most current model 

available at the time Delaware was performing its analysis. EPA has issued an updated motor 

vehicle emissions model known as the Motor Vehicle Emission Simulator or MOVES. In its 

announcement of this model, EPA established a grace period for continued use of MOBILE6.2 in 

transportation conformity determinations for transportation plans and TIPs, after which states and 

MPOs (other than California) must use MOVES for transportation plan and TIP conformity

determinations. This grace period will expire in March 2012 (or March 2013 once the extension 

becomes official). 

Additional information on the use of MOVES in SIPs and conformity determinations can 

be found in the December 2009, “Policy Guidance on the Use of MOVES2010 for State 

Implementation Plan Development, Transportation Conformity, and Other Purposes.” This 

guidance document is available at: http://www.epa.gov/otaq/models/moves/420b09046.pdf.

During the conformity grace period, the state and MPO(s) should use the interagency

consultation process to examine how MOVES2010 will impact their future transportation plan 

and TIP conformity determinations, including regional emissions analyses. For example, an 

increase in emission estimates due to the use of MOVES2010 may affect an area’s ability to 

demonstrate conformity for its transportation plan and/or TIP. Therefore, state and local planners 

should carefully consider whether the SIP and motor vehicle emissions budget(s) should be 

revised with MOVES2010 or if transportation plans and TIPs should be revised before the end of 

the conformity grace period, since doing so may be necessary to ensure conformity

determinations in the future.

We would expect that states and MPOs would work closely with EPA and the local 

FHWA and FTA offices to determine an appropriate course of action to address this type of 

situation if it is expected to occur. If Delaware chooses to revise its PM2.5 attainment plan, it 

should consult Question 7 of the December 2009, “Policy Guidance on the Use of MOVES2010 

for State Implementation Plan Development, Transportation Conformity, and Other Purposes,”

for information on requirements related to such revisions.

On November 17, 2011, DNREC submitted a SIP revision that is related to the PM2.5 and 

NOx onroad mobile source budgets that were established in the April 3, 2008 submittal. The 

budgets in the April 3, 2008 submittal were established using EPA’s MOBILE6.2 model. 
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However, effective March 2012 (or March 2013 once the extension becomes official), the 

MOVES model is required to be used in all planning and transportation conformity

determinations. The purpose of the supplemental SIP revision submitted on November 17, 2011,

is to 1) replace the onroad emissions budget in the April 3, 2008 submittal with a budget that is 

based on the MOVES model; 2) demonstrate that the MOVES based mobile source budget is 

consistent with attainment of the PM2.5 NAAQS by 2010; and 3) demonstrate that the 

contingency requirements of the CAA are met. This SIP revision only impacts PM2.5 and NOx 

emissions and calculations. More detailed information can be found in the TSD entitled, 

“Adequacy Findings for Motor Vehicle Emissions Budgets in the Attainment Demonstration for 

the Delaware Portion of the Philadelphia-Wilmington-New Jersey 1997 PM2.5 NAAQS 

Nonattainment Area,” January 11, 2012.

EPA MOVES model was used to quantify PM2.5 and NOx emission from onroad mobile 

sources. The emission levels for the onroad mobile emissions budget for New Castle County are 

shown in Table 12. See Appendix A of the November 17, 2011 submittal for the associated 2012 

MOVES input and output files.

Table 12. Revised Onroad Mobile Emission Budget (tpy)

County Emissions Budget

New Castle NOx PM2.5

6273 199

Delaware demonstrated attainment of the annual PM2.5 NAAQS in its April 3, 2008 

submittal by showing that the projected 2009 emissions (i.e. the 2009 emission levels after the 

implementation of all state and Federal control requirements) were less than the attainment 

targets (i.e. the emissions levels needed for attainment based on modeling). The same 

methodology is used to demonstrate that the MOVES based mobile budgets are consistent with 

attainment of the PM2.5 NAAQS. See Appendix B of the November 17, 2011submittal for the 

associated 2009 MOBILE6.2 and MOVES input and output files.

CMAQ modeling was conducted in the April 3, 2008 submittal to demonstrate that 

Delaware and the entire Philadelphia area would attain the PM2.5 NAAQS in 2010 (attainment 

date). See section 6 of the April 3, 2008 submittal. CMAQ modeling demonstrated that the 

Delaware emission levels, referred to as attainment target, shown in Table 13 are consistent with 

attainment of the annual PM2.5 NAAQS. 

Table 13. 2009 Attainment Target (tpy)

County NOx PM2.5

Kent 8554 1185

New Castle 23048 3249

Sussex 18001 3581

Statewide Total 49603 8015
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Attainment year (i.e. 2009) emission levels were projected in the April 3, 2008 submittal 

based on the final and enforceable state and Federal emission requirements. These projected 

2009 emission levels, referred to as projected 2009 emissions are shown in Table 14.

Table 14. Projected 2009 Emissions (tpy)

County NOx PM2.5

Kent 7799 989

New Castle 21807 3015

Sussex 11591 2571

Statewide Total 41197 6575

Table 15 compares the 2009 mobile emissions calculated using MOBILE6.2 and 

MOVES. See Appendix B of the submittal for the associated 2009 MOBILE6.2 and MOVES 

input and output files. 

Table 15. 2009 MOBILE6.2 and MOVES (tpy)

2009 MOBILE6.2 2009 MOVES MOVES Increase

County NOx PM2.5 NOx PM2.5 NOx PM2.5

Kent 1922 32 3488 109 1566 77

New Castle 4904 87 8448 257 3544 170

Sussex 2707 41 4764 147 2057 106

Totals 9533 160 16700 513 7167 353

Table 16 reflects the revised projected 2009 emissions using the MOVES model instead 

of MOBILE6.2, i.e. adding the MOVES increase and the projected 2009 emissions.

Table 16. Revised Projected 2009 Emissions (tpy)

County NOx PM2.5

Kent 9365 1066

New Castle 25351 3185

Sussex 13648 2677

Statewide Total 48364 6928

The revised projected 2009 emissions are demonstrated to be consistent with attainment 

if they are equal or lower than the 2009 attainment target. The revised projected 2009 emissions 

are compared to the attainment target in Table 17. This comparison shows that there is a surplus 

of 64 tons per year PM2.5 in New Castle County. This demonstrates that relative to direct PM2.5, 

the MOVES based mobile budgets are consistent with attainment.
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Table 17. Shortfall and Surplus by County and Statewide (tpy)

Attainment Target Revised Projected 

2009 Emissions

Surplus/Shortfall

County NOx PM2.5 NOx PM2.5 NOx PM2.5

Kent 8554 1185 9365 1066 -811 119

New Castle 23048 3249 24351 3185 -2303 64

Sussex 18001 3581 13648 2677 4353 904

Statewide 49603 8015 48364 6928 1239 1087

In addition, since 64 tpy PM2.5 emissions show that it is greater than the contingency

requirement of 26 tpy, the contingency requirement is demonstrated relative to PM2.5. See

section 9 of the April 3, 2008 submittal for the contingency requirements.

Because of the regional nature of secondarily-formed sulfate and nitrate, and the broad 

modeling domain of the CMAQ modeling, which included all of Delaware, emission reductions 

from Kent and Sussex counties, will contribute to attainment within New Castle County and the 

Philadelphia area. Kent and Sussex Counties are within the State of Delaware, contiguous to 

New Castle County, and are less than 200 kilometers away. EPA’s PM2.5 Implementation Rule 

specifically provides for the consideration of in-state NOX and SO2 reductions in their SIPs from 

sources up to 200 kilometers away from the non-attainment area boundaries. See PM2.5 

Implementation Rule, 72 FR 20586 at 20636. While there is a 2009 NOx shortfall in New Castle 

County, there is a statewide NOx surplus of 1,239 tpy. Therefore, the 2009 MOVES based 

emissions do not impair Delaware’s ability to meet the PM2.5 NAAQS.

In addition, since the 2009 NOx emissions of 1,239 tpy show that it is greater than the 

contingency requirement of 1,100 tpy NOx, the contingency requirement is demonstrated relative 

to NOx. See section 9 of the April 3, 2008 submittal for the contingency requirements.

For MVEBs to be approvable, they must meet, at a minimum, EPA’s adequacy criteria 

(40 CFR 93.118(e)(4)). The MVEBs for the Delaware portion of the Philadelphia area PM2.5 

attainment plan are being posted to EPA’s conformity website concurrently with the notice of 

proposed rulemaking (NPR). The public comment period will end at the same time as the public

comment period for the NPR. In this case, EPA is concurrently processing the action on the 

attainment plan and the adequacy process for the MVEBs contained therein. In the NPR, EPA is 

proposing to find the MVEBs adequate, and also proposing to approve the MVEBs as part of the 

attainment plan. The MVEBs cannot be used for transportation conformity until the attainment 

plan and associated MVEBs are approved in a final Federal Register notice, or EPA otherwise 

finds the budgets adequate in a separate action following the comment period. Our action on the 

Delaware portion of the Philadelphia area MVEBs will also be announced on EPA’s conformity

website: http://www.epa.gov/otaq/stateresources/transconf/index.htm, (once there, click on 

“Adequacy Review of SIP Submissions).
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D. SUMMARY AND RECOMMENDATIONS:

The PM2.5 attainment plan for the Delaware portion of the Philadelphia area meets the 

requirements of the CAA as described in the Clean Air Fine Particle Implementation Rule (April 

25, 2007, 72 FR 20586). The attainment plan supports a determination that the Delaware portion 

of the Philadelphia area attains the 1997 annual PM2.5 NAAQS. The attainment plan includes an 

attainment demonstration, MVEBs used for transportation conformity purposes, RACM/RACT

analysis, contingency measures, and the 2002 base year emission inventories. Therefore, we 

recommend approval of the PM2.5 attainment plan for the Delaware portion of the Philadelphia

area.