Delaware Redesignation Request and Maintenance Plan 

Under the 1997 Annual PM2.5

National Ambient Air Quality Standard

State Implementation Plan

For the New Castle County Portion of the 

Philadelphia-Wilmington, PA-NJ-DE 

Nonattainment Area for Fine Particles

Final

November 27, 2012
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

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Table of Contents

Acronym List .................................................................................................................................. 4

List of Tables .................................................................................................................................. 5

List of Figures................................................................................................................................. 5

EXECUTIVE SUMMARY ............................................................................................................ 6

1 Introduction............................................................................................................................. 8

1.1 Documentation Organization.......................................................................................... 8

2 Background............................................................................................................................. 8

2.1 Health Effects.................................................................................................................. 8

2.2 Philadelphia-Wilmington, PA-NJ-DE Nonattainment Area Designation ...................... 9

3 EPA Requirements for Redesignation .................................................................................. 10

3.1 NAAQS Compliance .................................................................................................... 11

3.1.1 EPA Requirements.................................................................................................... 11

3.1.2 Delaware Approach .................................................................................................. 11

3.2 Demonstration that the NAAQS for annual PM2.5, as published in 40 CFR 50.7, has 

been attained (requirement 1 of 3)................................................................................ 12

3.3 Ambient monitoring data quality assured in accordance with 40 CFR 58.10, recorded 

in the EPA air quality system (AQS) database, and available for public view 

(Requirement 2 of 3).............................................................................................. .....16

3.4 A commitment that, once redesignated, the state will continue to operate an appropriate 

monitoring network to verify the maintenance of the attainment status (requirement 3 

of 3)............................................................................................................................... 19

3.4.1 EPA Requirements.................................................................................................... 19

3.4.2 Delaware Approach .................................................................................................. 19

4 Permanent and Enforceable Emission Reductions ............................................................... 19

4.1 EPA Requirements........................................................................................................ 19

4.2 Delaware Approach ...................................................................................................... 20

4.2.1 Economic Conditions................................................................................................ 20

4.2.2 Meteorology.............................................................................................................. 21

4.2.3 Emission Inventory Improvements from 2002 to 2007 ............................................ 23

4.3 Enforceable and Permanent PM2.5, NOx and SO2 Measures that Contributed to 

Improved Air Quality after 2002 and through 2007 ..................................................... 28

4.3.1 Delaware-specific Control Measures........................................................................ 28
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

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4.3.2 Federal Control Measures......................................................................................... 29

5 SIP Completeness - Fully Approved SIP, Section 110 and Part D Requirements ............... 34

5.1 EPA Requirements........................................................................................................ 34

5.2 Delaware Approach ...................................................................................................... 34

5.3 Part D Plan Requirements for Nonattainment Areas.................................................... 35

6 Maintenance Plan.................................................................................................................. 37

6.1 EPA Requirements........................................................................................................ 37

6.2 Delaware Approach ...................................................................................................... 38

7 Attainment Inventory............................................................................................................ 39

7.1 EPA Requirements........................................................................................................ 39

7.2 Delaware Approach ...................................................................................................... 39

7.3 2007 Attainment Year Inventory .................................................................................. 39

8 Maintenance Demonstration ................................................................................................. 40

8.1 EPA Requirements........................................................................................................ 40

8.2 Delaware Approach ...................................................................................................... 41

8.2.1 2017 and 2025 Projection Inventories ...................................................................... 41

8.2.2 2017 and 2025 Mobile Source Emissions Budgets................................................... 44

8.2.3 Control Measures for Maintenance of Good Air Quality ......................................... 46

8.2.4 Delaware-specific NOx, PM2.5 or SO2 Control Measures (Effective Post 2007)... 48

8.2.5 Federal Control Measures (Effective or Phased-in Post 2007)................................. 49

8.2.6 Future Emissions Reductions Programs ................................................................... 50

8.2.7 Controls to Remain in Effect .................................................................................... 51

9 Verify Continued Attainment ............................................................................................... 51

9.1 EPA Requirements........................................................................................................ 51

9.2 Delaware Approach ...................................................................................................... 51

10 Contingency Measures.......................................................................................................... 52

10.1 EPA Requirements........................................................................................................ 52

10.2 Delaware Approach ...................................................................................................... 52

11 Other Delaware Commitments ............................................................................................. 56

11.1 Commitment to Revise Plan ......................................................................................... 56

11.2 Public Participation....................................................................................................... 56

12 Conclusions........................................................................................................................... 56
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

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Acronym List

AQS - EPA’s Air Quality System

CAA - Federal Clean Air Act

CAAA - Clean Air Act Amendments of 1990 

CFR - Code of Federal Regulations (of the United States)

CSAPR - Cross-State Air Pollution Rule 

DAQ - DNREC Division of Air Quality

DelDOT - Delaware Department of Transportation

dv - Design Value

DNREC - Delaware Department of Natural Resources and Environmental 

Control

EGU - Electric Generating Unit

GDP - Gross Domestic Product

EPA - United States Environmental Protection Agency 

FHWA - Federal Highway Administration

FR - United States Federal Register

FRM - Federal Reference Method

FTA - Federal Transit Authority

I/M - Inspection and Maintenance Program

MANEVU - Mid-Atlantic and Northeast Visibility Union

MARAMA - Mid-Atlantic Regional Air Management Association

NESCUAM - Northeast States for Coordinated Air Use Management

LRTP - Long Range Transportation Plan 

MLK - Martin Luther King Blvd. monitor in Wilmington, Delaware

MPO - Metropolitan Planning Organization

mmBTU - Million British Thermal Unit

NAA - Non-Attainment Area

NAAQS - National Ambient Air Quality Standard 

NEI - National Emission Inventory

NOx - Oxides of Nitrogen 

NAA - Non-attainment area 

PM2.5 - Particulate Matter with an aerodynamic diameter of 2.5 microns or less

RACM - Reasonably Available Control Measure

RACT - Reasonably Available Control Technology 

RPO - Regional Planning Organization

SIP - State Implementation Plan 

(SAFETEA-LU) - Safe, Accountable, Flexible, Efficient Transportation Equity Act – A 

Legacy for Users 

SO2 - Sulfur Dioxide

TIP - Transportation Improvement Program

tpy - Tons per Year

TSD - Technical Supporting Document

VOC - Volatile Organic Compound 

WILMAPCO - Wilmington Area Planning Council 
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

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List of Tables

Table 3-1 2007-2012 Annual Means (ug/m3) 

Table 3-2 Design Values: 2007-2009, 2008-2010 and 2009-2011 

Table 3-3 PM2.5 Monitoring Site General Information

Table 3-4 PM2.5 Monitor Site Specific Information

Table 4-1 Monthly Average Min, Max and Mean Temperatures and 

Precipitation, including Total Precipitation

Table 4-2 Philadelphia NAA annual PM2.5 averages - 2001-2011 

Table 4-3 New Castle County 2002-2007 Emission Changes

Table 4-4 New Castle County 2002-2007 Emissions Comparison

Table 7-1 2007 New Castle County Emissions (tpy)

Table 8-1 Comparison of emissions for the years 2007, 2017 and 2025

Table 8-2 Reductions and % Change of NOx emissions for the years 2007, 2017 and 2025

Table 8-3 Reductions and % Change of PM2.5 emissions for the years 2007, 2017 and 2025

Table 8-4 Reductions and % Change of SO2 emissions for the years 2007, 2017 and 2025

Table 8-5 Growth Assumptions Used in Emission Inventory Projections

Table 8-6 New Castle County Maintenance Plan On-Road Mobile Source 

Emissions Budgets

Table 8-7 Post-2007 Emission Reductions due to Control Measures

Table 10-1 Schedule for Permit Revisions or Rule Revisions for Contingency Measures

List of Figures

Figure 2-1 Philadelphia PM2.5 Nonattainment Area Boundaries

Figure 3-1 Delaware’s PM2.5 Monitoring Site Locations

Figure 4-1 2002 – 2011 Delaware Gross Domestic Product – All Industry

Figure 4-2 Philadelphia NAA – 2001 to 2011 annual PM2.5 trends

Figure 4-3 Philadelphia NAA – annual PM2.5 trends (avg. all monitors)

Figure 4-4 Philadelphia NAA – 2003 to 2011 PM2.5 3-Year Rolling Averages
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

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EXECUTIVE SUMMARY

This request for redesignation to attainment and maintenance plan is a State 

Implementation Plan (SIP) revision for the Delaware portion1 of the Philadelphia-Wilmington, 

PA-NJ-DE fine particulate matter (PM2.5) nonattainment area (Philadelphia NAA). This area 

was designated as a nonattainment area on January 5, 2005 (70 FR 944), with an effective date of

April 5, 2005. 

CAAA Section 107 establishes specific requirements to be met in order for a 

nonattainment area to be considered for redesignation to attainment. Section 107 includes a 

requirement for an approved Maintenance Plan before an area can be redesignated from 

nonattainment to attainment of a National Ambient Air Quality Standard (NAAQS). This 

redesignation request and maintenance plan SIP revision provides technical information that

supports this request to redesignate the Delaware portion of the Philadelphia NAA area to 

attainment of the 1997 annual PM2.5 NAAQS. 

PM2.5 air quality has improved in New Castle County as a result of the implementation of 

State and Federal emissions control measures. The air quality improvement is due to permanent 

and enforceable emissions control measures. The entire Philadelphia NAA has certified and 

quality assured ambient air quality monitoring data for the 3-year periods 2007-2009, 2008-2010

and 2009-2011 that all demonstrate attainment of the 1997 PM2.5 NAAQS. The purpose of this 

redesignation request and maintenance plan is to request that the United States Environmental 

Protection Agency (EPA) redesignate the Delaware portion of the Philadelphia NAA to 

attainment for this standard pursuant to the provisions of Section 107 of the federal Clean Air 

Act (CAA) (42 U.S.C. 7407). In summary, the plan includes:

 A demonstration that attainment of the 1997 PM2.5 air quality standards for the 

Philadelphia NAA will continue through 2025. 

 An attainment emissions inventory that identifies the level of emissions in the area that 

is sufficient to attain the NAAQS, and projected future emissions inventories showing 

that future emissions in the area will not exceed the level of the attainment inventory 

over the 10-year maintenance period. 

 Contingency measures to be implemented in the unlikely event of a subsequent violation 

of the air quality standard. The contingency measures listed in the Plan will be triggered 

to expeditiously correct any future exceedances. 

 On-road motor vehicle emissions budgets for 2017 and 2025 for use in transportation 

conformity determinations to assure that any increases in emissions from this sector do 

not jeopardize continued attainment of the 1997 annual PM2.5 standards during the 

maintenance period.

Based on this presentation, New Castle County, Delaware meets the requirements for 

redesignation under the CAA (Section 107(d)(3)) and EPA guidance for fine particles. 

 

1 Pennsylvania and New Jersey Departments of Environmental Protection are responsible for developing similar 

plans for their portion of the Philadelphia NAA.
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

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Consistent with the authority granted to EPA, the State of Delaware requests that New Castle 

County, Delaware be redesignated to attainment for the 1997 annual fine particles standard 

simultaneously with EPA approval of this Delaware State redesignation request and Maintenance 

Plan for the New Castle County portion of the Philadelphia NAA.
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

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1 Introduction

The State of Delaware requests that the EPA redesignate the Delaware portion of 

Philadelphia NAA to attainment for the 1997 annual PM2.5 NAAQS pursuant to the provisions 

Section 107 of the CAA (42 U.S.C. 7407).

2

 Since the designations for the 1997 NAAQS for this 

pollutant were published, the area’s PM2.5 air quality has improved due to permanent and 

enforceable emission reductions. Air quality in the area is significantly better than required by 

this standard. This document demonstrates that PM2.5 air quality in the Philadelphia area will 

remain compliant with the 1997 annual PM2.5 NAAQS, as measured by a monitoring network 

that meets all federal requirements, through 2025. 

Delaware is also requesting that EPA concurrently approve, as a revision to the Delaware 

state implementation plan (SIP), the related Section 175A maintenance plan, as described in 

Sections 6-8 of this document. This plan includes mobile vehicle emissions budgets for the 

interim year of 2017 and the out year of 2025. It also contains contingency measures that will be 

implemented in the unlikely event that the area experiences an exceedance of the 1997 PM2.5

NAAQS. The maintenance plan ensures that good PM2.5 air quality will be maintained through 

2025.

1.1 Documentation Organization 

This document presents Delaware’s discussions and analysis of summarized air quality 

data and emission inventories, PM2.5 control measures and applicable CAA and EPA

requirements in support of Delaware’s request for redesignation to attainment under the 1997 

annual PM2.5 NAAQS. Supporting documentation and data, such as Technical Support 

Documents (TSD), calculation spreadsheets, model input and output files, and other related data 

are available on the CD enclosed with this redesignation request and maintenance plan. Much of 

the documentation that is referenced in the report, but not contained on the CD, has been 

compiled in electronic files located at the Division of Air Quality offices in Dover, Delaware and 

are available for review upon request by the public.

2 Background

2.1 Health Effects

PM2.5, also known as fine particulate matter or fine particles, is defined as any airborne 

particle of solid or liquid matter that is less than or equal to 2.5 micrometers in diameter. PM2.5

is not a single pollutant, but is a sum of all pollutants that have diameters less than 2.5 

micrometers. For reference, 2.5 micrometers is about 1/30th the diameter of a human hair. 

Sources of PM2.5 and PM2.5 precursors include, most significantly, coal-fired power 

plants and other combustion sources, fires, emissions from motor vehicles, windblown dust, and 

natural emissions from trees and the oceans. These sources can be divided up into two types of 

 

2 After EPA redesignates the Philadelphia nonattainment area to attainment, it will be known as the Philadelphia 

Maintenance Area, or Philadelphia MA.
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

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sources; primary and secondary. Primary sources directly emit fine particulate matter into the 

atmosphere without any chemical change occurring to the pollutant. Secondary sources are 

sources from which precursor chemical species are released into the atmosphere, which then 

react with other chemical species in the atmosphere to create fine particulate matter. Some 

species which comprise fine particulate matter are sulfates, ammonium nitrate, soot, sea salt, 

organic carbon, elemental carbon and metals (crustal metals, transitional metals, and potassium).

Exposure to high levels of PM2.5 adversely affects human health. The main impacts of 

PM2.5 on human health are on the respiratory system and the cardiovascular system. Children, 

the elderly, and individuals with pre-existing pulmonary or cardiac disease are the most 

susceptible to PM2.5 pollution. Complications that can arise from exposure to PM2.5 include 

decreased lung function, chronic bronchitis; respiratory symptoms such as asthma attacks and 

difficulty breathing, nonfatal heart attacks, irregular heartbeat, and premature death in 

individuals with pulmonary or cardiac disease.

2.2 Philadelphia-Wilmington, PA-NJ-DE Nonattainment Area Designation

On July 18, 1997, EPA established a health-based PM2.5 NAAQS at 15.0 micrograms per 

cubic meter (μg/m3) based on a 3-year average of annual mean PM2.5 concentrations (‘‘the 

annual PM2.5 NAAQS’’ or ‘‘the annual standard’’) (62 FR 36852). At that time, EPA also 

established a 24-hour standard of 65 μg/m3 (‘‘1997 24-hour standard’’). See, 40 CFR 50.7. 

EPA established these standards based on significant evidence and numerous health studies 

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

Following promulgation of a new or revised NAAQS, EPA is required by the 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. On January 5, 2005, EPA 

published its air quality designations for the 1997 PM2.5 NAAQS based upon air quality 

monitoring data for calendar years 2001–2003 (70 FR 944). These designations became 

effective on April 5, 2005. The Philadelphia Area, which includes New Castle County in 

Delaware; Burlington, Camden, and Gloucester Counties in New Jersey; and Bucks, Chester, 

Delaware, Montgomery, and Philadelphia Counties in Pennsylvania (see Figure 2-1), was 

designated nonattainment for the 1997 annual PM2.5 NAAQS during this designations process 

(40 CFR 81.308, 81.832, and 81.339). The attainment date for the 1997 annual PM2.5 NAAQS is 

as expeditiously as practicable, but no more than five years from the date of designation. See, 40 

CFR 51.1004(a)). Therefore, the attainment date for the Philadelphia Area was April 5, 2010. 

On October 17, 2006 (71 FR 61144), EPA retained the 1997 annual PM2.5 NAAQS at 15

μg/m3 based on a 3-year average of annual mean PM2.5 concentrations, and promulgated a 24-

hour standard of 35 μg/m3 based on a 3-year average of the 98th percentile of 24-hour 

concentrations (the ‘‘2006 24-hour standard’’). On November 13, 2009, EPA published the area 

designations for the 2006 24-hour standard (74 FR 58688). That action, effective on December 

14, 2009, designated the same Philadelphia Area as nonattainment for the 2006 24-hour standard 

and clarified that the Philadelphia Area is designated as unclassifiable/attainment for the 1997 
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

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24-hour PM2.5 standard. This redesignation request addresses the 1997 annual PM2.5 standard. 

The 2006 24-hour PM2.5 standard will be addressed in a separate document. 

In response to legal challenges of the 2006 annual standard, the U.S. Court of Appeals for 

the District of Columbia Circuit (D.C. Circuit) remanded this standard to EPA for further 

consideration. See, American Farm Bureau Federation and National Pork Producers Council, 

et al. v. EPA, 559 F.3d 512, (D.C. Circuit 2009). However, given that the 1997 and 2006 annual 

PM2.5 standards are identical, attainment of the 1997 annual standard would also indicate 

attainment of the remanded 2006 annual standard. 

Figure 2-1 Philadelphia PM2.5 Nonattainment Area Boundaries 

3 EPA Requirements for Redesignation

Section 107(d)(3)(E) of the CAA allows states to request nonattainment areas to be 

redesignated to attainment provided certain criteria are met. The criteria for redesignating a 

nonattainment area to attainment are as follows:

 EPA has determined that the area attained the NAAQS. For the 1997 PM2.5 NAAQS, the 

areas must show that the average of the annual average values from three (3) consecutive 

calendar years of quality-assured air quality monitoring data is 15.0 μg/m3or lower.

 The request must contain a showing that the improvement in air quality is due to 

permanent and enforceable reductions in emissions resulting from the implementation of 

the applicable SIP.
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

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 The applicable implementation plan must be fully approved by EPA under Section 110(k) 

of the CAA, and the redesignation request must contain a determination that the state 

meets all applicable requirements for the area under Section 110 and Part D.

 EPA has fully approved a maintenance plan, including contingency measures, for the area 

under Section 175A of the Act. Section 175A requires demonstrating that the area will 

maintain (continue to attain) the standard for at least ten years after redesignation to 

attainment, and that contingency measures be implemented if a violation is monitored at 

any time during the ten-year maintenance period. 

This document addresses each of these requirements. EPA has published applicable 

guidance in a memorandum from John Calcagni, Director, Air Quality Management Division, 

entitled Procedures for Processing Requests to Redesignate Areas to Attainment (redesignation 

guidance), issued September 4, 1992, to Regional Air Directors. 40 CFR Part 51, Subpart Z, 

entitled Provisions for Implementation of PM2.5 National Ambient Air Quality Standards

(implementation rule) provides additional information. The State of Delaware has based this 

redesignation request and maintenance plan on the redesignation guidance and the 

implementation rule, supplemented with additional guidance received through coordination with 

EPA Region 3 staff.

3.1 NAAQS Compliance

3.1.1 EPA Requirements

CAA Section 107(d)(3)(E)(i) addresses attaining the standard. This demonstration 

should rely upon ambient air quality data. The data that are used to demonstrate attainment 

should be the product of ambient monitoring that is representative of the area of highest 

concentration. Additionally, the data should be collected and quality-assured in accordance with 

40 CFR Part 58 and recorded in the Air Quality System (AQS) in order for it to be available to 

the public for review. 

3.1.2 Delaware Approach

EPA’s published guidance document, “Procedures for Processing Requests to 

Redesignate Areas to Attainment” (September 4, 1992), which details specific requirements 

regarding the collection and use of ambient air monitoring data needed to support a redesignation 

request. Before the Philadelphia NAA can be redesignated to attainment for the 1997 annual 

NAAQS, the City of Philadelphia, Delaware Department of Natural Resources and 

Environmental Control (DNREC), Division of Air Quality (DAQ), the New Jersey Department 

of Environmental Protection and the Pennsylvania Department of Environmental Quality must 

each demonstrate that the annual PM2.5 NAAQS has been attained in their respective 

jurisdictions of the Philadelphia NAA. PM2.5 monitoring data must show that violations of the 

NAAQS are no longer occurring within the NAA.

This showing must rely on three complete, consecutive calendar years of quality assured 

data. Further, the air monitoring data must be quality assured in accordance with 40 CFR 58.10, 
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

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recorded in EPA’s Air Quality System (AQS) database, and made available to the public. 

Finally, Delaware DAQ must commit to continue to operate an appropriate monitoring network 

to verify the maintenance of the attainment status, once the area has been redesignated to 

attainment. Taken together, there are three primary requirements: 

1. A demonstration that the NAAQS for annual PM2.5, as published in 40 CFR 50.13, has 

been attained.

2. Ambient monitoring data quality assured in accordance with 40 CFR 58.10, recorded in 

the EPA air quality system (AQS) database, and available for public view.

3. A commitment that once redesignated, the state will continue to operate an appropriate 

monitoring network to verify the maintenance of the attainment status.

3.2 Demonstration that the NAAQS for annual PM2.5, as published in 40 CFR 50.7, has 

been attained (requirement 1 of 3)

The States of Delaware and New Jersey, and the Commonwealth of Pennsylvania, and 

the City of Philadelphia (‘‘the States’’), submitted complete quality assured air quality 

monitoring data into the EPA Air Quality System (AQS) database for the 2007–2011 monitoring 

periods. The States then certified that data. DAQ has also obtained preliminary 2012 

monitoring data. The criteria for determining if an area is attaining the 1997 annual PM2.5

NAAQS are set out in 40 CFR 50.13 and Appendix N of 40 CFR 50. The annual PM2.5 NAAQS 

is met when the annual design value (dv) is less than or equal to 15.0 micrograms per cubic 

meter (μg/m3). Three years of valid annual means are required to produce a valid annual 

standard design value. A year meets data completeness requirements when at least 75 percent of 

the scheduled sampling days for each quarter have valid data. The use of less than complete data 

is subject to the approval of EPA, which may consider factors such as monitoring site 

closures/moves, monitoring diligence, and nearby concentrations in determining whether to use 

such data. 

While most of the monitoring data submitted by the States was complete, several 

monitors in the Philadelphia NAA had less than four quarters of complete data for one or more 

years during the 2007–2009, 2008–2010 and 2009-2011 monitoring periods. For these monitors, 

EPA applied the data substitution test set out in the April 1999 EPA guidance document 

‘‘Guideline on Data Handling Conventions for the PM NAAQS.” The ‘‘maximum quarter’’ 

substitution test (Max-Q) identified in the guidance document is used for monitors with missing 

data. Maximum recorded values are substituted for the missing data. The resulting design value 

is compared to the standard. The monitor passes if the design value with maximum values 

substituted meets the standard. If the monitor does not pass using the Max-Q Sub test, then 

another statistical method was required. The statistical method used to determine whether an 

incomplete monitor would have met the NAAQS, is to first establish a linear regression 

relationship between the target monitor and another monitor in or close to the nonattainment 

area. The linear regression would then be used to fill in the missing data for the target monitor.

The results are checked with an additional statistical procedure (“bootstrapping”), to give a 

“diagnostic” design value verifying if the conclusion of attainment is correct. 
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

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2007-2009 and 2008-2010 monitoring data

Considering 2007–2009 data, six monitors had less than complete data, with five of those 

monitors passing the Max-Q Sub test. However, the New Garden, PA monitor’s missing data 

could not be evaluated using the Max-Q test. Therefore, EPA performed a linear regression 

analysis and bootstrapping to show that the New Garden monitor also met the 1997 annual 

NAAQS. In summary, all Philadelphia NAA monitors meet the 1997 annual NAAQS for the 

2007-2009 and 2008-2010 monitoring periods. More details of EPA’s analysis can be found in 

the EPA Technical Support Documents (TSD).

3,4

2009-2011 monitoring data

Considering 2009–2011 data, three monitors had less than complete data (New Garden, 

PA, and Bellefonte and Newark in Delaware - monitor IDs 420290100, 100031003 and 

100031012). However, based on email correspondence with EPA Region 3, all of the 2009-

2011 monitoring data passed the max-Q substitution test, and the 2009-2011 monitoring values 

as received from EPA are included in the air quality tables within this plan (see table 3-1).

5 

Furthermore, according to the PM2.5 implementation rule, the attainment date for the 

Philadelphia Area is April 5, 2010, and monitoring data from the period 2007–2009 is used to 

determine if the area attained by April 5, 2010. 

Table 3-1 shows the PM2.5 2007-2011 quality assured and certified annual means for each 

monitor in the Philadelphia NAA for the years 2007–2011. Table 3-2 shows the 3-year design 

values for the 2007-2009, 2008-2010, and 2009-2011. The highest 3-year design values based 

on 2007-2009, 2008-2010, and 2009-2011 data are 13.9 μg/m3, 13.8 μg/m3 and 13.7 μg/m3, all of 

which are less than the level of the annual PM2.5 NAAQS of 15.0 μg/m3. Based on preliminary 

2012 data from AQS, the 1st quarter values also continue to show attainment based on the highest 

value of 14.6 μg/m3in Philadelphia, (monitor ID 421010004).

Therefore, complete quality-assured and certified ambient air quality monitoring data 

demonstrate that the air quality has met the 1997 NAAQS for annual PM2.5 in the Philadelphia 

NAA. The NAAQS attainment, accompanied by decreases in emission levels discussed in 

Section 7, supports a redesignation to attainment for the New Castle County, Delaware portion 

of the Philadelphia NAA based on the requirements in Section 107(d)(3)(E) of the CAA as 

amended.

 

3 77 FR 3223 (January 23, 2012).

4 77 FR 28782 (May 16, 2012).

5 E. V. Rosa, EPA Region 3, August 27, 2012
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

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Table 3-1 2007-2012 Annual Means (ug/m3)

09-11 Completeness 

(5)

State County Monitor ID 2007 2008 2009 2010 2011 Status 

(3)

Data 

Substitution

(4)

PreLim.

2012

DE Bellefonte 100031003 13.4 13.0 10.2 10.2 9.4 C Max-Q 8.5

Lums 100031007 12.5 11.5 10.0 10.0 8.8 C Max-Q 8.0

Newark 100031012 13.4 12.5 10.6 10.4 10.4 C Max-Q 8.8

MLK 100032004 14.4 13.5 11.2 10.6 10.3 C 9.7

NJ Camden 340071007 13.8 11.9 9.5 9.5 10.1 C 8.6

Gloucester 340150004 13.3 11.5 9.3 9.1 9.4 C Max-Q 9.3

PA Bucks 420170012 13.0 12.7 10.8 10.5 11.5 C 10.6

Chester 420290100 14.1 13.7 14.1 13.8 13.3 C Max-Q 8.9

Delaware 420450002 14.7 13.9 12.4 13.5 12.6 C 10.7

Montgomery 420910013 13.1 11.7 10.4 9.5 10.3 C 8.6

Philadelphia 421010004 13.7 13.0 10.8 10.7 13.2 C 14.6

Philadelphia 421010024 (1) 12.9 12.0 9.9 9.6 - Inc -

Philadelphia 421010047 14.3 13.5 11.1 11.0 11.4 C 9.9

Philadelphia 421010055 (6) 13.5 11.3 11.3 11.4 C 9.8

Philadelphia 421010057 12.0 13.3 11.1 10.9 11.4 C 10.0

Philadelphia 421011002 (2) - - 9.0 Inc 13.4

NAA Avg. (all monitors) 13.5 12.7 10.8 10.7 10.8 10.8

Notes:

Data Source:

 2007-2010 annual means: 77 FR 3147 

 2011 annual means: EPA Region 3 (see footnote 5)

 2012 preliminary data was obtained from AQS (as of July 31, 2012)

1. Monitoring site was shutdown on January 1, 2011.

2. Monitoring site commenced operation on June 1, 2010. However, as of July 30, 2012, AQS 2010 data for this 

monitor was not available. (see footnote 5)

3. This column indicates whether the monitoring data from the monitor meet the completeness requirement (C) or 

not (Inc) for each quarter of the 3-year period. 

4. This column identifies the data substitution technique utilized to deem 'complete' the annual design value of the 

incomplete monitors. “Max-Q” denotes that the monitor passed the maximum quarter substitution test. 

5. As determined by EPA (see footnote 5)

6. Monitor started operating 2008 

2012 is Preliminary and not certified – only the 1st quarter was available from AQS (as of July 31, 2012)
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

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Table 3-2 Design Values: 2007-2009, 2008-2010 and 2009-2011 

State County Monitor ID

07-09

DV

US EPA 

Analysis

(3)

08-10 

DV

US EPA

Analysis

(3)

09-11 

DV

US EPA

Analysis

(3)

DE Bellefonte 100031003 12.2 C 11.1 C 9.9 Max Q

Lums 100031007 11.3 Max Q 10.5 C 9.6 Max Q

Newark 100031012 12.2 Max Q 11.2 Max Q 10.5 Max Q

MLK 100032004 13.0 Max Q 11.7 Max Q 10.7 C

NJ Camden 340071007 11.7 C 10.3 C 9.7 C

Gloucester 340150004 11.4 C 10.0 C 9.3 Max Q

PA Bucks 420170012 12.2 C 11.3 C 10.9 C

Chester 420290100 13.9 Bootstrap 13.8 Max Q 13.7 Max Q

Delaware 420450002 13.7 C 13.3 C 12.7 C

Montgomery 420910013 11.7 C 10.5 C 10.1 C

Philadelphia 421010004 12.5 C 11.5 C 11.6 C

Philadelphia 421010024 11.6 Max Q 10.5 C 9.8 Inc (1)

Philadelphia 421010047 13.0 Max Q 11.9 C 11.2 C

Philadelphia 421010055 12.4 C 12.0 C 11.4 C

Philadelphia 421010057 12.1 C 11.7 C 11.1 C

Philadelphia 421011002 - - - 9 Inc (2)

Philadelphia NAA Average μg/m3 

(all monitors) 12.3 11.4 10.8

Notes:

Sources of data:

o 2007-2009 and 2008-2010 design values: 77 FR 3147 

o 2009-2011 design values: EPA Region 3 (EPA, footnote 5)

o 2012 preliminary data was obtained from AQS (as of July 31, 2012)

1. Monitoring site was shutdown on January 1, 2011.

2. Monitoring site commenced operation on June 1, 2010.

3. This column indicates whether the monitoring data from the monitor meet the completeness requirement 

(C) or not (Inc.) for each quarter of the 3-year period. This also column identifies the data substitution 

technique utilized to deem 'complete' the annual design value of the incomplete monitors. “Max Q Sub” 

denotes that the monitor passed the maximum quarter substitution test. (EPA, footnote 5)
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

16

3.3 Ambient monitoring data quality assured in accordance with 40 CFR 58.10, 

recorded in the EPA air quality system (AQS) database, and available for public 

view (Requirement 2 of 3)

Delaware DAQ has quality assured all data in accordance with 40 CFR 58.10 and all 

other federal requirements. Delaware DAQ has recorded the data in the AQS database and, 

therefore, the data are available to the public.

Delaware began official PM2.5 monitoring in 1999. Delaware’s PM2.5 network consists of 

seven (7) monitoring sites, one of which employs a collocated monitor. There are four (4) sites 

in New Castle County, two (2) in Kent County and one (1) in Sussex County. Table 3-3 lists the 

PM2.5 sites in New Castle County (the only nonattainment county), including the nature of the 

area, and general site descriptions. Table 3-4 contains more specific information for each PM2.5

monitoring site in New Castle County.

Table 3-3 PM2.5 Monitoring Site General Information

Site Name & AQS ID Land Use Setting Metropolitan Statistical Area

Bellefonte

10-003-1003 Residential Suburban Philadelphia - Wilmington

MLK

10-003-2004 Commercial Urban Philadelphia - Wilmington

Newark

10-003-1012 Residential Suburban Philadelphia - Wilmington

Lums Pond

10-003-1007 Agricultural Rural Philadelphia - Wilmington

Table 3-4 PM2.5 Monitor Site Specific Information

Site Name & AQS ID Parameter Start Date Objective

Bellefonte

10-003-1003 PM2.5 1/1/1999 Population Exposure,Attainment Status

MLK

10-003-2004

PM2.5 1/1/1999 Maximum concentration,

Attainment Status

PM2.5 speciation 6/1/2001 PM2.5 Characterization

Black Carbon 1/1/2001 Diesel PM2.5 Indicator

Newark

10-003-1012 PM2.5 12/15/1999 Population Exposure,Attainment Status

Lums Pond

10-003-1007 PM2.5 1/1/1999 Transport/Background,Attainment Status
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

17

The primary goal of the PM2.5 monitoring network in Delaware is to determine the status 

of the ambient air with respect to the 24-hour and annual average PM2.5 NAAQS. In accordance 

with federal regulations, state agencies must operate at least the minimum number of required 

PM2.5 sites listed in 40 CFR Part 58 Appendix D Table D-5. These required monitoring stations 

or sites must be sited to represent community-wide air quality. In addition, the following 

specific criteria also apply:

(1) At least one monitoring station is to be sited in a population-oriented area of expected 

maximum concentration. 

(2) For areas with more than one required station, a monitoring station is to be sited in an 

area of poor air quality.

(3) Each State shall install and operate at least one PM2.5 site to monitor for regional 

background and at least one PM2.5 site to monitor regional transport. 

Figure 3-1 shows the locations of Delaware’s PM2.5 monitors. All data from these 

monitors are measured using EPA approved federal reference methods (FRM). All PM2.5

monitoring sites are located appropriately and are eligible for comparison to the annual and daily 

PM2.5 NAAQS. 

The standard monitoring schedule is one in three days, with one site (MLK-Wilmington) 

monitoring every day. MLK is also the designated collocated site, with the collocated monitor 

designated as MLK-b operating on a one in six day schedule. All data submitted to EPA’s Air 

Quality System (AQS) in a timely manner in accordance to the schedule prescribed by EPA.

Chemical speciation is encouraged at sites where the chemically resolved data would be 

useful in developing SIPs and supporting atmospheric or health effects related studies. Chemical 

speciation is conducted at MLK in Wilmington and Dover in Kent County. The PM2.5 chemical 

speciation sites include analysis for elements, selected anions and cations, and carbon. 
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

18

Figure 3-1 Delaware’s PM2.5 Monitoring Site Locations

Delaware’s original PM2.5 monitoring network design and monitor siting were completed 

in accordance with EPA requirements and guidance as stated in 40 CFR Part 58 Appendices D 

and E, and the EPA Office of Air Quality Planning & Standards (OAQPS) document “Guidance 

for Network Design and Optimum Site Exposure for PM2.5 and PM10” (EPA 1997a). Final

network documents were submitted to EPA Region 3 in June 1998, and EPA approved 

Delaware’s PM2.5 monitoring network. 

Delaware Annual Ambient Air Monitoring Network Reviews, including PM2.5, have been 

completed each year in accordance with 40 CFR Part 58 Appendix D and subsequently 

submitted to EPA Region 3 for approval.

In fulfillment of the federal 103 grant requirements, Delaware submits annual Delaware 

Data Quality Assessments for PM2.5 speciation data and PM2.5 FRM data to EPA Region 3. All 

data complies with appropriate federal and state requirements, including 40 CFR Part 50 

Appendices L and N, and 40 CFR Part 58 Appendix A.

In fulfillment of the federal 103 grant requirements, Delaware also submits annual PM2.5

Speciation Monitoring Network Review and Monitoring Strategy reports to EPA Region 3. The 

PM2.5 speciation network design and monitor siting follows EPA requirements and guidance as 

stated in 40 CFR Part 58 Appendices D and E, and the documents “Guidance for Network 

Design and Optimum Site Exposure for PM2.5 and PM10" (EPA 1997a), “Particulate Matter 
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

19

(PM2.5) Speciation Guidance” (EPA 1999), and “Guideline on Speciated Particulate 

Monitoring” (EPA 1999a).

3.4 A commitment that, once redesignated, the state will continue to operate an 

appropriate monitoring network to verify the maintenance of the attainment status

(requirement 3 of 3).

3.4.1 EPA Requirements

Once an area has been redesignated, the states must continue to operate an appropriate air 

quality monitoring network in accordance with 40 CFR Part 58, to verify the area's attainment 

status. In cases where measured mobile source parameters (for example, vehicle miles traveled) 

have changed over time, the state may also need to perform a saturation monitoring study to 

determine the need for and location of additional permanent monitors.

3.4.2 Delaware Approach

The State of Delaware operates a monitoring network that is significantly more robust 

than required by federal regulation. New Castle County is nonattainment for the 1997 PM2.5

annual standard and the 2006 daily PM2.5 standard. Accordingly, Delaware is required to 

maintain its current monitoring network. 

As mentioned above, states must continue to operate an appropriate air quality 

monitoring network in accordance with 40 CFR Part 58, to verify the area's attainment status. 

Information on Delaware’s monitoring network was discussed in Section 3.3.

The State of Delaware commits to operating and maintaining an air quality network for 

PM2.5 monitoring that meets all federal requirements. However, should changes become 

necessary in the future Delaware DAQ will consult with EPA Region 3 prior to making changes 

to the existing monitoring network. Delaware DAQ will continue to quality assure the 

monitoring data to meet the requirements of 40 CFR 58 and all other federal requirements. 

Delaware DAQ will enter all data into AQS on a timely basis in accordance with federal 

guidelines.

4 Permanent and Enforceable Emission Reductions

4.1 EPA Requirements

As required by Section 107(d)(3)(E)(iii) and in EPA redesignation guidance, states must 

be able to reasonably attribute its air quality improvements to emission reductions of precursors 

or direct PM2.5 that are permanent and enforceable. Attainment resulting from temporary 

reductions in emission rates (such as reduced production or shutdown due to temporary adverse 

economic conditions) or unusually favorable meteorological conditions does not qualify.
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

20

4.2 Delaware Approach 

Delaware demonstrates the improvement in air quality described in 3.2 of this document 

was not a result of temporary adverse economic conditions (4.2.1) or unusually favorable 

meteorology (4.2.2). Delaware then demonstrates that the improvements in air quality described 

in 3.2 of this document are reasonably attributable to permanent and enforceable emission 

reductions of direct PM2.5 and PM2.5 precursors (4.2.3 and 4.3). 

4.2.1 Economic Conditions

Delaware evaluated the role economic conditions may have played in the improvement

in air quality described in 3.2 of this document by evaluating the Gross Domestic Product 

(GDP) growth rate. The GDP growth rate is an indicator of economic health. If the GDP 

growth rate is increasing, it is an indication that the activity of emitting sources are increasing. 

Conversely, if the GDP is declining it is an indication that the activity of emitting sources may 

be reduced because of economic conditions. 

Delaware specific GDP for all industries, obtained from the U.S. Bureau of Economic 

Analysis (BEA), is presented in Figure 4-1. 

Figure 4-1 2002 – 2011 Delaware Gross Domestic Product – All Industry

0

10000

20000

30000

40000

50000

60000

70000

2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

GDP all industry (mil $)
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

21

Figure 4-1 shows that except for a decline between 2007 and 20086, all industries 

increased GDP in every year from 2002 through 2011. Of specific relevance to air quality is the 

comparison between the time when Delaware’s air quality did not meet the PM2.5 standard (i.e., 

2002-2006) and the time when it did (i.e., 2007-2011). The GDP in every year between 2007 

and 2011 is greater than every year between 2002 and 2006. This analysis of GDP indicates that 

economic conditions did not contribute to the improvement in air quality.

4.2.2 Meteorology

Delaware evaluated the role meteorology may have played in the improvement in air 

quality described in 3.2 of this document by evaluating temperature and precipitation data. 

Temperature and precipitation are the primary meteorological variables that impact the 

formation of PM2.5. Temperature and precipitation impact both the emission from sources 

(e.g., power plant emissions are highest during very hot and cold weather), and ambient PM2.5

concentrations (e.g., precipitation removes PM2.5 from the air through deposition).

Delaware analyzed historical meteorological data for Wilmington, Delaware, which is 

the location where Delaware’s highest PM2.5 concentrations are recorded (monitor ID = 

100032004). Table 4-1 shows 3-year monthly averages for: minimum, maximum and means 

temperatures (in degrees Fahrenheit), as well as total precipitation by monthly average and for 

the entire 3-year periods 2001-2003 and 2007-2009.7

 

6 According to the Delaware Department of Labor the reason for the decline between 2007 and 2008 was an 

economic recession that began in Delaware in December 2007.

7 Recall that 2001-2003 average PM2.5 concentration was used to calculate the initial Philadelphia NAA design 

values causing nonattainment, and the 2007-2009 average PM2.5 concentration was used to calculate design values 

which demonstrate attainment. Therefore, by comparing the meteorology between these two 3-year periods we can 

evaluate the effect that meteorology had on PM2.5 concentrations during a time when the air quality was 

nonattainment and a time when it was attainment. 
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

22

Table 4-1 Monthly Average Min, Max and Mean Temperatures and 

Precipitation, including Total Precipitation 

2001-

2003

2007-

2009

2001-

2003

2007-

2009

2001-

2003

2007-

2009

2001-

2003

2007-

2009

Month

3-yr 

AVG 

Min. 

Temp.

(

o F)

3-yr 

AVG 

Min. 

Temp.

(

o F)

3-yr 

AVG 

Max. 

Temp.

(

o F)

3-yr 

AVG 

Max. 

Temp.

(

o F)

3-yr 

Mean 

Temp.

(

o F)

3-yr 

Mean 

Temp.

(

o F)

Total 

Precip.

(in)

Total 

Precip. 

(in)

Jan 25.2 26.5 40.1 41.8 32.7 34.2 7.6 8.0

Feb 26.3 25.1 43.2 42.5 34.8 33.8 8.5 6.6

Mar 33.1 33.6 51.5 53.3 42.2 43.5 14.4 10.5

Apr 43.0 43.4 63.6 63.1 53.3 53.3 6.3 14.6

May 51.2 52.1 70.2 73.5 60.7 62.8 12.7 10.0

Jun 62.1 63.5 80.3 82.3 71.2 72.9 19.1 12.1

Jul 66.0 66.1 84.6 86.0 75.2 76.1 6.6 11.8

Aug 68.1 66.2 86.3 84.6 77.2 75.4 8.9 11.3

Sep 58.2 59.3 77.4 78.5 67.8 68.9 13.4 10.6

Oct 45.6 48.3 65.3 68.0 55.4 58.1 11.3 13.6

Nov 38.2 38.7 57.6 54.9 47.9 46.8 8.8 7.5

Dec 29.6 29.6 45.4 44.5 37.5 37.0 11.4 17.8

Annual 

average 3-

Yr Average

Temp., and 

3-Yr Total

Precipitation

45.5 46.0 63.8 64.4 54.7 55.2 129 134.3

From Table 4-1, we see that the annual average 3-year monthly averages for minimum, 

maximum, and mean temperatures for 2007-2009 are slightly higher than those temperatures 

during the years 2001-2003 (e.g., the 2001-2003 annual average mean temperature was 54.7 

degrees while the 2007-2009 annual average mean temperature was 55.2 degrees). Higher 

temperatures typically correlate with higher ambient PM2.5 concentrations, which indicate 

temperature is a factor that negatively impacted air quality. 

From Table 4-1, we see that 3-year total precipitation was about 4.3% higher in 2007-

2009 compared to 2001-2003 (134.8 in. and 129 in. respectively). Increased precipitation 

disfavors PM2.5 formation, because it results in deposition of existing ambient PM2.5 and 

precursors. Because total precipitation was only slightly higher during the years showing 

attainment (2007-2009), increased precipitation did not likely contribute to the improved air 

quality. 

In summary, 1) the annual average 3-year monthly min, max, and mean temperatures are 

very similar between the nonattainment timeframe (2001-2003) and the attainment timeframe 

(2007-2009), and 2) the total precipitation is also very similar between those two periods. 
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

23

Therefore, although Meteorology will always play a role in the formation of PM2.5, DAQ 

concludes that meteorology did not play a significant role in air quality improvements for 

redesignation purposes under the 1997 annual PM2.5 NAAQS. 

4.2.3 Emission Inventory Improvements from 2002 to 2007

It was demonstrated in 4.2.1 and 4.2.2 that neither economic conditions nor meteorology 

significantly contributed to the improved air quality. Given this, it follows that permanent and 

enforceable reductions of PM2.5, NOX and SO2,

8

from a variety of state and federal measures are 

the primary reason for the improved air quality and attainment of the standard for fine particles. 

As discussed previously, EPA published its air quality designations for the 1997 PM2.5

NAAQS based upon air quality monitoring data for calendar years 2001–2003 (70 FR 944). 

Since 2001, permanent and enforceable reductions of primary PM2.5 and secondary PM2.5

precursor emissions have contributed to improvements in PM2.5 air quality and to the attainment 

of the PM2.5 NAAQS. To help demonstrate how emission reductions have improved air quality, 

we evaluate air quality trends, which can be seen in Table 4-2 and Figures 4-2 and 4-3, and 

discuss emission reductions due to permanent and enforceable control measures. 

The values in Table 4-2 and Figure 4-2 represent the annual average concentration as 

calculated from the four calendar quarterly averages at each monitoring site. As Table 4-2 

shows, the highest annual value in the Philadelphia NAA nonattainment area has decreased from 

17.6 μg/m3in 2001 (monitor ID 100032004) to 13.3 μg/m3in 2011, or 4.3 μg/m3, which 

represents a 24% drop. The annual average is the basic statistic used in determining trends and 

compliance with the annual average NAAQS. 

 

8 Ammonia and volatile organic compounds (VOC) are contributors to PM2.5 formation, however, they are not 

considered significant overall contributors in the Philadelphia NAA. Therefore, this demonstration of air quality 

improvements due to permanent and enforceable emission reductions of precursors or direct PM2.5 focuses on SO2, 

PM2.5, and NOX.
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

24

Table 4-2 Philadelphia NAA annual averages - 2001-2011 

State Monitor ID County 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

DE 100031003 Bellefonte 15.6 14.0 14.8 13.9 14.3 12.3 13.4 13.0 10.2 10.2 9.4

100031007 Lums 14.5 13.0 13.3 13.2 13.8 11.4 12.5 11.5 10.0 10.0 8.8

100031012 Newark 15.8 14.3 14.8 14.5 14.4 12.7 13.4 12.5 10.6 10.4 10.4

100032004 MLK 17.6 14.8 15.5 14.9 15.0 14.7 14.4 13.5 11.2 10.6 10.3

NJ 340071007 Camden 14.2 13.9 13.9 13.2 14.3 12.4 13.8 11.9 9.5 9.5 10.1

340150004 Gloucester 14.5 12.3 13.8 12.4 14.2 9.3 13.3 11.5 9.3 9.1 9.4

PA 420170012 Bucks 14.5 14.2 14.4 13.0 14.3 12.2 13.0 12.7 10.8 10.5 11.5

420290100 Chester ND ND 15.6 14.3 15.9 12.6 14.1 13.7 14.1 13.8 13.3

420450002 Delaware 15.9 14.7 15.3 15.0 16.9 14.2 14.7 13.9 12.4 13.5 12.6

420910013 Montgomery 14.9 13.6 13.9 12.0 12.5 12.1 13.1 11.7 10.4 9.5 10.3

421010004 Philadelphia 16.5 14.4 14.8 13.9 14.2 13.5 13.7 13.0 10.8 10.7 13.2

421010024 Philadelphia 14.6 13.7 13.2 12.8 12.9 12.4 12.9 12.0 9.9 9.6 -

421010047 Philadelphia 17.0 15.6 16.1 14.4 15.1 15.4 14.3 13.5 11.1 11.0 11.4

421010055 Philadelphia ND ND ND ND ND ND ND 13.5 11.3 11.3 11.4

421010057 Philadelphia ND ND ND ND ND ND 12.0 13.3 11.1 10.9 11.4

421011002 Philadelphia ND ND ND ND ND ND ND ND ND ND 9.0

NAA Average - all monitors 15.5 14.0 14.6 13.7 14.4 12.7 13.5 12.7 10.8 10.7 10.8

 Monitor 421010055 in Philadelphia County, Pennsylvania, started operating in 2008.

 Monitor 4210010057 started operating in the 3rd Quarter, 2007

 Monitor ID 421011002 started operating in January, 2011.

 ND = monitor did not operate or was not in existence in that year.
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

25

Figure 4.2 Philadelphia NAA – 2001 to 2011 annual PM2.5 trends

Figure 4-3 also shows 2001-2011 monitoring data, but instead of showing each 

monitor trend, all the monitors in the Philadelphia NAA were averaged together, by year

to give a “summary-view.” 

Figure 4.3 Philadelphia NAA – yearly PM2.5 trends (avg. all monitors)
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

26

Figure 4-4 shows the downward trends since 2001 using 3-year rolling-averages (i.e., 

design values). 

Figure 4.4 Philadelphia NAA – 2003 to 2011 PM2.5 3-Year Rolling Averages

Figure 4-5 is a variation on Figure 4-4 and plots the average design values per year,

calculated from all monitors in the Philadelphia NAA. 

Figure 4.5 Philadelphia NAA – Average of Design Values(all monitors) 

 
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

27

Some of these air quality improvements were a result of emissions reductions which were

due to the application of tighter federal emission standards on motor vehicles and fuels, and 

some due to the requirements of the federal NOx SIP Call. Others were due to Delawarespecific control measures. Section 4.3 of this plan describes these reductions in more detail, 

along with an explanation of their regulatory status. 

One of the ways states have demonstrated how controls have contributed to reductions is 

by comparing a base year emission inventory to the attainment year emission inventory. The

EPA’s PM2.5 Emissions Inventory Guidance required that states with PM2.5 NAAQS 

nonattainment areas prepare and submit a 2002 base year inventory of anthropogenic sources of

direct PM2.5 and precursors of secondary PM2.5 emissions, namely NOx and SO2. The 2002 base

year inventory included emissions from point, non-point, on-road mobile and non-road mobile

emissions. The 2002 base year was used in Delaware’s Annual PM2.5 Attainment Demonstration 

SIP (submitted to EPA in April, 2008). It was picked as the base year for this annual 

redesignation request because it reflects one of the years in which Delaware was designated 

nonattainment (e.g., 2001-2003). 

The Philadelphia NAA came into attainment for the 1997 annual PM2.5 NAAQS based on 

2007-2009 monitoring data. Delaware chose to use 2007 as the attainment year (e.g., one of the 

three years during which the area attained the standard), from which future inventories are 

projected in the accompanying maintenance plan. 

The 2007 inventory was developed through the MARAMA regional planning process.

Documentation of how the 2007 attainment year was developed can be found in Technical 

Support Document for the Development of the 2007 Emission Inventory for Regional Air Quality 

Modeling in the Northeast / Mid-Atlantic Region Version 3.3. January 23, 2012. The 

MARAMA 2007 TSD includes annual emissions for carbon monoxide (CO), ammonia (NH3), 

oxides of nitrogen (NOx), particulate matter (PM), sulfur dioxide (SO2), and volatile organic 

compounds (VOC). The PM species in the inventory are categorized as: filterable and 

condensable particles with an aerodynamic diameter less than or equal to a nominal 10 and 2.5 

micrometers (i.e., PM10-PRI and PM25-PRI); filterable particles with an aerodynamic diameter 

less than or equal to a nominal 10 and 2.5 micrometers (i.e., PM10-FIL and PM25-FIL); and 

condensable particles (PM-CON). Note that PM10-PRI equals the sum of PM10-FIL and PMCON, and PM25-PRI equals the sum of PM25-FIL and PM-CON. 

However, for purposes of this plan, Delaware only provides NOx, PM2.5 and SO2, because 

as Delaware determined in its 2008 PM2.5 Attainment Demonstration, only those pollutants are 

regulated as PM2.5 and PM2.5 precursors.
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

28

Table 4-3 summarizes 20029 and 2007 emissions by major source category and by 

pollutant for New Castle County, as well as the change in terms of tons per year (tpy) and 

percent decrease/increase.

10

Table 4-3 New Castle County 2002-2007 Emission Changes

Source 

Sector

NOx PM2.5 SO2

2002 2007 Δ 

(tpy)

Δ 

(%) 2002 2007 Δ (tpy)

Δ 

(%)

2002 2007 Δ 

(tpy)

Δ 

(%)

Point 9,157 6,635 2,522 28% 1,733 1,335 398 23% 47,070 13,380 33,690 72%

Non-point 1,513 1,293 220 15% 1,073 1,207 -134 -12% 780 630 150 19%

On-road 11,799 10,577 1,222 10% 209 324 -115 -55% 326 100 226 69%

Non-road 8,279 4,580 3,699 45% 415 327 88 21% 2,061 1,118 943 46%

All Sectors 30,748 23,084 7,664 25% 3,430 3,193 237 7% 50,237 15,228 35,009 70%

By comparing the 2002 and 2007 inventories, we see that total direct PM2.5 emissions 

were reduced by 237 tons per year, and that NOx emissions decreased by 7,664 tons per year. 

These reductions were primarily from point and non-road mobile sources. SO2 emissions 

decreased much more significantly - by 35,009 tons per year - largely due to reductions from the 

Delaware City Refinery controls put into effect in 2006 as a result of a Federal Consent decree. 

These sizeable emissions reductions, as well as corresponding reductions in upwind areas and 

other nearby states, resulted in a substantial improvement in PM2.5 air quality in the Philadelphia 

NAA, ultimately resulting in attainment of the 1997 PM2.5 NAAQS.

4.3 Enforceable and Permanent PM2.5, NOx and SO2 Measures that Contributed to 

Improved Air Quality after 2002 and through 2007

4.3.1 Delaware-specific Control Measures

 7 DE Admin. Code 1144, Control of Stationary Generator Emissions, SO2, PM, VOC and 

NOX emission control, State-wide, Effective January 2006. EPA SIP approval date 

08/11/2010 (75 FR 48566).

 7 DE Admin. Code 1148, Control of Stationary Combustion Turbine Electric Generating 

Unit Emissions, NOX emission control, State-wide, Effective July, 2007. This regulation 

was approved into the Delaware SIP by EPA on 08/11/2010. (75 FR 48566).

 

9 The 2002 annual PM2.5 base year and emission controls are discussed in more detailed in Delaware’s PM2.5 

Attainment Demonstration, submitted to EPA in April, 2008.

10 The 2002 emission summary has not been revised to incorporate the higher emissions estimates for on-road 

mobile sources using the new EPA’s MOVES model, and from the new paved road dust equation. The 2007 

emissions inventory does include the higher emission factors for NOx and PM2.5 from the EPA MOVES model and 

from the new paved road dust equation. This makes the 2002 base year NOx and PM2.5 emissions lower than they 

would be if using the 2007 methodologies; and the actual emission reductions between 2002 and 2007 are greater 

than what is shown in Table 4-3. 
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

29

 7 DE Admin. Code 1142. Section 1, Control of NOX Emissions from Industrial Boilers, 

NOX emission control, Effective December 2001. This regulation was approved into the 

Delaware SIP by EPA on 11/22/01 (67 FR 70315). Section 2, Control of NOX Emissions 

from Industrial Boilers and Process Heaters at Petroleum Refineries, NOX emission 

control, New Castle County, Effective July 2007. This regulation was revised and 

approved into the Delaware SIP by EPA on 5/15/12 (77 FR 28489).

 Consent Decree with Premcor Refinery at Delaware City (formerly Motiva Enterprises), 

New Castle County, Control of SO2, and NOX Emissions from Boilers and Heaters, 

Effective 2006, Civil Action No. H-01-0978 lodged in the United States Court for the 

Southern District of Texas on March 21, 2001 (the federal consent decree).

 7 DE Admin. Code 1131, Low Enhanced Inspection and Maintenance. Delaware’s 

enhanced I/M program was approved into the Delaware SIP by EPA on September 30, 

1999 (64 FR 52657). Revisions to the enhanced I/M program were approved by EPA on 

11/26/2003 (68 FR 228). 

4.3.2 Federal Control Measures

Area sources

EPA’s New Source Performance Standards for Woodstoves (NSPS). These standards are 

codified at 40 CFR Part 60, subpart AAA. The final standards were promulgated in 1988 (53 FR 

5860). The rule requires manufacturers of new residential wood heaters (e.g., wood stoves) to 

design heaters to meet particulate emission (PM) limits, have representative model lines tested 

by EPA-accredited labs, and attach EPA labels and hangtags after EPA approval. For the 

general woodstoves and fireplaces category (SCC 2104008000) USEPA computed a weighted 

average distribution based on 19.4% fireplaces, 71.6% old woodstoves, 9.1% new woodstoves 

using 2002 Platform emissions for PM2.5. These fractions are based on the fraction of emissions 

from these processes in the states that did not have the “general woodstoves and fireplaces” SCC 

in the 2002 NEI. 

Control Programs Included in the NMIM/NONROAD Model

Under 40 CFR Part 89, EPA adopted standards for emissions of NOX, hydrocarbons

(HC), and carbon monoxide (CO) from several groups of nonroad engines, including industrial 

spark-ignition engines and recreational nonroad vehicles. Industrial spark-ignition engines 

power commercial and industrial applications and include forklifts, electric generators, airport 

baggage transport vehicles, and a variety of farm and construction applications. Nonroad 

recreational vehicles include snowmobiles, off-highway motorcycles, and all-terrain vehicles.

These rules were initially effective in 2004 and will be fully phased in by 2012.

Control of Air Pollution; Determination of Significance for Nonroad Sources and 

Emission Standards for New Nonroad Compression Ignition Engines at or Above 37 Kilowatts 
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

30

59 FR 31036, June 17, 1994. This rule establishes Tier 1 exhaust emission standards for HC, 

NOx, CO, and PM for nonroad compression-ignition (CI) engines ≥37kW (≥50hp). Marine 

engines are not included in this rule. The start dates and pollutants affected vary by hp category 

as follows: 

 50-100 hp: Tier 1,1998; NOx only

 100-175 hp: Tier 1, 1997; NOx only

 175-750 hp: Tier 1, 1996; HC, CO, NOx, PM

 >750 hp: Tier 1, 2000; HC, CO, NOx, PM

Emissions for New Nonroad Spark-Ignition Engines At or Below 19 Kilowatts; Final 

Rule 60 FR 34581. July 3, 1995. This rule establishes Phase 1 exhaust emission standards for 

HC, NOx, and CO for nonroad spark-ignition engines ≤19kW (≤25hp). This rule includes both 

handheld (HH) and non-handheld (NHH) engines. The Phase 1 standards became effective in 

1997 for: 

 Class I NHH engines (<225cc), 

 Class II NHH engines (≥225cc), 

 Class III HH engines (<20cc), and 

 Class IV HH engines (≥20cc and <50cc). 

The Phase 1 standards became effective in 1998 for: Class V HH engines (≥50cc) 

Final Rule for New Gasoline Spark-Ignition Marine Engines; Exemptions for New 

Nonroad Compression-Ignition Engines at or Above 37 Kilowatts and New Nonroad SparkIgnition Engines at or Below 19 Kilowatts 61 FR 52088. October 4, 1996. This rule establishes

exhaust emission standards for HC+NOx for personal watercraft and outboard (PWC/OB) 

marine SI engines. The standards were phased in from 1998-2006.

Control of Emissions of Air Pollution from Nonroad Diesel Engines 63 FR 56967 

October 23, 1998. This final rule sets Tier 1 standards for engines under 50 hp, phasing in from 

1999 to 2000. The rule also phases in more stringent Tier 2 standards for all engine sizes from 

2001 to 2006, and even more stringent Tier 3 standards for engines rated over 50 hp from 2006 

to 2008. The Tier 2 and Tier 3 standards apply to NMHC+NOx, CO, and PM. The start dates 

by hp category and tier are as follows: 

 hp: < 8kW and 8-19kW Tier 1,2000; Tier 2, 2005; no Tier 3

 25-50 hp: Tier 1, 1999; Tier 2, 2004; no Tier 3

 50-100 hp: Tier 2, 2004; Tier 3, 2008

 100-175 hp: Tier 2, 2003; Tier 3, 2007

 175-300 hp: Tier 2, 2003; Tier 3, 2006

 300-600 hp: Tier 2, 2001, Tier 3, 2006

 600-750 hp: Tier 2, 2002; Tier 3, 2006

 >750 hp: Tier 2, 2006, no Tier 3
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

31

This rule does not apply to marine diesel engines above 50 hp.

Phase 2: Emission Standards for New Nonroad Non-handheld Spark Ignition Engines At 

or Below 19 Kilowatts 64 FR 15207. March 30, 1999. This rule establishes Phase 2 exhaust 

emission standards for HC+NOx for nonroad non-handheld (NHH) spark-ignition engines 

≤19kW (≤25hp). The Phase 2 standards for Class I NHH engines (<225cc) became effective on 

August 1, 2007 (or August 1, 2003 for any engine initially produced on or after that date). The 

Phase 2 standards for Class II NHH engines (≥225cc) were phased in from 2001-2005.

Phase 2: Emission Standards for New Nonroad Spark-Ignition Handheld Engines At or 

Below 19 Kilowatts and Minor Amendments to Emission Requirements Applicable to Small 

Spark-Ignition Engines and Marine Spark-Ignition Engines; Final Rule 65 FR 24268 April 25, 

2000. This rule establishes Phase 2 exhaust emission standards for HC+NOx for nonroad 

handheld (HH) spark-ignition engines ≤19kW (≤25hp). The Phase 2 standards were phased in 

from 2002-2005 for Class III and Class IV engines and were phased in from 2004-2007 for Class 

V engines.

Control of Emissions From Nonroad Large Spark-Ignition Engines and Recreational 

Engines (Marine and Land-Based); Final Rule 67 FR 68241. November 8, 2002. This rule 

establishes exhaust and evaporative standards for several nonroad categories: 

1) Two tiers of emission standards are established for large spark-ignition engines over 

19 kW. Tier 1 includes exhaust standards for HC+NOx and CO and was phased in from 

2004-2006. Tier 2 became effective in 2007 and includes exhaust standards for HC+NOx 

and CO as well as evaporative controls affecting fuel line permeation, diurnal emissions 

and running loss emissions.

2) Exhaust and evaporative emission standards are established for recreational vehicles, 

which include snowmobiles, off-highway motorcycles, and all-terrain vehicles (ATVs). 

For snowmobiles, HC and CO exhaust standards are being phased-in from 2006-2012. 

For off-highway motorcycles, HC+NOx and CO exhaust emission standards were phased 

in from 2006-2007. For ATVs, HC+NOx and CO exhaust emission standards were

phased in from 2006-2007. Evaporative emission standards for fuel tank and hose 

permeation apply to all recreational vehicles beginning in 2008.

3) Exhaust emission standards for HC+NOx, CO, and PM for recreational marine diesel 

engines over 50 hp during 2006-2009, depending on the engine displacement. These are 

“Tier 2” equivalent standards.

Control of Emissions of Air Pollution from Nonroad Diesel Engines and Fuel; Final Rule 

(Clean Air Nonroad Diesel Rule – Tier 4) 69 FR 38958, June 29, 2004. This final rule sets Tier 

4 exhaust standards for CI engines covering all hp categories (except marine and locomotives), 

and also regulates nonroad diesel fuel sulfur content.

1) The Tier 4 start dates and pollutants affected vary by hp and tier as follows:
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

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Rated Power First Year that

Standards Apply

PM

(g/hp-hr)

NOx

(g/hp-hr)

hp < 25 2008 0.30 -

25 ≤ hp < 75 2013 0.02 3.5*

75 ≤ hp < 175 2012-2013 0.01 0.30

175 ≤ hp < 750 2011-2013 0.01 0.30

hp ≥ 750 2011-2014

2015

0.075

 0.02/0.03**

2.6/0.50†

0.50††

* The 3.5 g/hp-hr standard includes both NOx and nonmethane hydrocarbons. 

† The 0.50 g/hp-hr standard applies to gensets over 1200 hp. 

** The 0.02 g/hp-hr standard applies to gensets; the 0.03 g/hp-hr standard applies to other 

engines.

†† Applies to all gensets only.

2) This rule will reduce nonroad diesel fuel sulfur levels in two steps. First, starting in 

2007, fuel sulfur levels in nonroad diesel fuel will be limited to a maximum of 500 ppm, 

the same as for current highway diesel fuel. Second, starting in 2010, fuel sulfur levels in 

most nonroad diesel fuel will be reduced to 15 ppm.

Control of Emissions from Nonroad Spark-Ignition Engines and Equipment; Final Rule 

(Bond Rule), 73 FR 59034 October 8, 2008. This rule establishes exhaust and evaporative 

standards for small SI engines and marine SI engines.

1) Phase 3 HC+NOx exhaust emission standards are established for Class I NHH 

engines starting in 2012 and for Class II NHH engines starting in 2011. There are no new 

exhaust emission standards for handheld engines. New evaporative standards are adopted 

for both handheld and non-handheld equipment. The new evaporative standards control 

fuel tank permeation, fuel hose permeation, and diffusion losses. The evaporative 

standards begin in 2012 for Class I NHH engines and 2011 for Class II NHH engines. 

For handheld engines, the evaporative standards are phased-in from 2012-2016.

2) More stringent HC+NOx and CO standards are established for marine SI PWC/OB 

engines beginning in 2010. In addition, new exhaust HC+NOx and CO standards are 

established for stern-drive and inboard (SD/I) marine SI engines also beginning in 2010. 

High performance SD/I engines are subject to separate HC+NOx and CO exhaust 

standards that were phased-in from 2010-2011. New evaporative standards were also 

adopted for all marine SI engines that control fuel hose permeation, diurnal emissions, 

and fuel tank permeation emissions. The hose permeation, diurnal, and tank permeation 

standards take effect in 2009, 2010, and 2011, respectively.
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

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On-Road Emissions Programs

In the 2007 heavy-duty highway rule, which is codified in 40 CFR Part 86, Subpart P, 

EPA set a PM emission standard for new heavy-duty engines of 0.01 grams per brake 

horsepower-hour (g/bhp-hr). This standard took full effect for diesel engines in the 2007 model 

year. This rule included standards for NOX and non-methane hydrocarbons (NMHC) of 

0.20g/bhp-hr and 0.14g/bhp-hr, respectively. These diesel engine NOX and NMHC standards 

were successfully phased in together between 2007 and 2010. The rule also required that sulfur 

in diesel fuel be reduced to facilitate the use of modern pollution control technology on these 

trucks and buses. EPA required a 97% reduction in the sulfur content of highway diesel fuel --

from levels of 500 parts per million (ppm) for low sulfur diesel to 15ppm for ultra-low sulfur 

diesel. The reductions in sulfur content engendered similar reductions in SO2 emissions. These 

requirements were successfully implemented on the timeline in the regulation.

Federal Tier 1 New Vehicle Emission and New Federal Evaporative Emission Standards:

Under CAA Section 202, EPA established federal motor vehicle emission standards (Tier I 

standards), which were phased in beginning with model year 1994. The benefits of this program 

are reflected in the 2002 base year inventory and the 2007 attainment year inventory. This 

federally implemented program affects light duty vehicles and light duty trucks. The regulations 

require more stringent exhaust emission standards as well as a uniform level of evaporative 

emission controls.

The Tier 2 vehicle and gasoline sulfur program, as codified in Subpart H of 40 CFR Part 

80, 40 CFR Part 85, and 40 CFR Part 86, became effective in the 2005 model year. This 

program for fleet averaging of on-road vehicles is modeled after the California LEV II 

standards. The Tier 2 program allows manufacturers to produce vehicles with emissions ranging 

from relatively dirty to very clean, but the mix of vehicles a manufacturer sells each year must 

have average NOX emissions below a specified value. Mobile emissions continue to benefit 

from this program as motorists replace older, more polluting vehicles, with cleaner vehicles. 

Delaware participated in the Ozone Transport Commission (OTC) National Low 

Emission Vehicle Program: Under the OTC National Low Emission Vehicle (NLEV) program, 

automobile manufacturers agreed to comply with tailpipe standards that were more stringent than 

EPA could mandate prior to model year 2004. For the OTC states, starting with the model year 

1999 all new vehicles sold in the region must comply with the more stringent LEV standards.

Once manufacturers committed to the program, the standards became enforceable in the same 

manner in which other federal motor vehicle emission control requirements were enforceable.

The program was in place nationwide for model year 2001, and the benefits of this program are 

reflected in the 2002 base year inventory and the 2007 attainment year inventory.

In additional to the federal Tier 1 and 2 programs, NLEV, and the federal 2007 heavy 

duty highway rule, Delaware has instituted enhanced vehicle emissions inspection and 

maintenance (DE Admin Code 1131-Low Enhanced Inspection and Maintenance) requirements 

in New Castle County and Kent County. The requirements involve mandating regional vehicle 

emission I/M programs that are stricter than basic programs, as required under Section182 and 

202 of the CAA. Before 1994, basic automobile emissions testing checked only tailpipe 
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

34

emissions while idling and sometimes at 2,500 rpm. For Delaware, the Low Enhanced I/M 

procedures includes the use of On Board Diagnostic (OBD) system evaluations, fuel system 

pressure test and a gas cap test. The procedures also include an anti-tampering inspection of the 

catalytic converter, gas cap and fuel inlet restrictor. The OBD evaluations provide a more 

complete inspection, checking for excess evaporative emissions and other issues that might 

affect emissions from the vehicle. 

5 SIP Completeness - Fully Approved SIP, Section 110 and Part D Requirements 

5.1 EPA Requirements

States must provide assurances that the applicable implementation plan has been fully 

approved by EPA under Section 110(k) and must satisfy all requirements that apply to the area. 

An area cannot be redesignated if a required element of its plan is the subject of disapproval; a 

finding of failure to submit or to implement the SIP; or partial, conditional, or limited approval.

For purposes of redesignation, states must also meet all requirements of Section 110 and 

Part D of the CAA that were applicable prior to submittal of the complete redesignation request. 

The general elements required in a SIP are listed in Section 110(a). These elements include 

procedures for air quality monitoring and modeling; criteria for establishing stationary source 

controls, monitoring and reporting; implementation of permitting programs under Part C 

(Prevention of Significant Deterioration or PSD) and Part D (New Source Review or NSR); and 

provisions for public involvement. Subpart 1 of Part D consists of general requirements 

applicable to all areas which are designated nonattainment based on a violation of the NAAQS. 

Subpart 4 of Part D consists of more specific requirements applicable to particulate matter 

(specifically to address PM10). However, for the purpose of implementing the 1997 PM2.5

standard, the EPA’s Implementation Rule stated Subpart 1, rather than Subpart 4, is appropriate 

for the purpose of implementing PM2.5 (72 FR 20589).

5.2 Delaware Approach

Delaware submitted its annual PM2.5 attainment demonstration to EPA on April 5, 2008. 

It was subsequently revised to update onroad mobile emissions based on the MOVES model, and 

submitted to EPA on May 3, 2012. EPA has not completed rulemaking on the 2008 SIP or the 

May 3, 2012 Revision to the 2008 PM2.5 SIP. However, EPA Region 3 has informed DAQ that 

they have a Consent Decree which requires final action on Delaware’s attainment plan by March 

29, 2013.

11 Therefore, Delaware expects that the 2008 attainment demonstration and its May 3, 

2012 revision will be fully approved by the EPA as required under Section 110(k).

Section 110(a) of the CAA contains the general requirements for a SIP. Delaware 

concludes that, as EPA has stated in previous rulemaking,

12 only the section 110 and part D 

requirements that are linked with a particular area’s designation are the relevant measures which 

 

11 EPA Region 3 comments, M. Pino (October 22, 2012)

12 See EPA’s proposed approval of Ohio’s redesignation request for the Ohio portion of the Huntington-Ashland 

nonattainment area for the 1997 PM2.5 NAAQS. (76 FR 79593)
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

35

DAQ may consider in evaluating a redesignation request. Further, DAQ believes that the other 

section 110 elements that are not connected with nonattainment plan submissions, and not linked 

with an area’s attainment status, are also not applicable requirements for purposes of 

redesignation. DAQ understands that a state remains subject to these requirements after an area 

is redesignated to attainment.

The requirements of section 110(a)(2) are statewide requirements that are not linked to 

the PM2.5 nonattainment status of the Philadelphia NAA. Therefore, DAQ believes that these 

SIP elements are not applicable requirements for purposes of review of the state’s PM2.5

redesignation request. 

5.3 Part D Plan Requirements for Nonattainment Areas

Nonattainment Areas in General 

CAA Section 172(c) – In April of 2008, DAQ submitted to EPA the Delaware State 

Implementation Plan for Attainment of the PM2.5 Annual National Ambient Air Quality Standard 

- Attainment Demonstration. Mobile budgets in the 2008 SIP were revised in January of 2012 in

the SIP entitled, Proposed Revision to Delaware’s 2008 State Implementation Plan for 

Attainment of the PM2.5 Annual National Ambient Air Quality Standard - Attainment 

Demonstration, to account for changes in the new EPA model, MOVES. This plan demonstrated

attainment of the annual PM2.5 NAAQS by 2010 based on implementation of a combination of 

federal measures, other regional controls, mobile source controls and local controls on industrial 

sources of direct PM2.5, NOx and SO2. In addition, the base year inventory requirement under 

CAA 172(c)(3) will be met when EPA fully approves the 2002 base year inventory submitted 

with the Delaware 2008 State Implementation Plan for Attainment of the PM2.5 Annual National 

Ambient Air Quality Standard - Attainment Demonstration. and the 2012 Proposed Revision to 

Delaware’s 2008 State Implementation Plan for Attainment of the PM2.5 Annual National 

Ambient Air Quality Standard - Attainment Demonstration.

CAA Section 176(c) was established under the CAA to address conformity. Conformity 

plays an important role in helping states and tribal regions improve air quality in those areas that 

do not meet the NAAQS. Under the separate general and transportation conformity rules, federal 

agencies must work with State, tribal, and local governments in nonattainment and maintenance 

areas to ensure that federal actions, including highway and transit projects, conform to the 

initiatives established in the applicable state or tribal implementation plan.

General Conformity

On November 30, 1993, EPA promulgated a set of regulations, known as the General 

Conformity Regulations, which apply to non-transportation projects (i.e., projects not adding or 

expanding highways and transit). These regulations ensured that these types of federal actions 

also conformed to the SIPs. (58 FR 63214) The purpose of the General Conformity Rule is to:

 Ensure that federal activities do not interfere with the budgets in the state 

implementation plans (SIPs); 
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

36

 Ensure the attainment and maintenance of the national ambient air quality standards 

(NAAQS); and 

 Ensure that actions do not cause or contribute to new violations of a NAAQS

General conformity must be met for any federal action, defined as an activity engaged in 

by a department or agency of the federal government, or supported in any way by the federal 

government (including via financial assistance, licenses, permits, or approvals). The Federal 

Agency must make a determination that the activity conforms to the applicable State 

Implementation Plan before commencing the activity. 

A conformity analysis must be conducted by the lead Federal Agency if a federal action 

would result in the generation of air emissions that would exceed conformity threshold levels of 

pollutants for which an air basin that is designated as a nonattainment or maintenance area under 

the NAAQS, or if emissions from the action are deemed regionally significant. A conformity 

analysis must demonstrate that the project emissions would conform, and thus would not degrade 

air quality in the impacted air basin. Conformity can be demonstrated via emission offsets, SIP 

provisions, or air quality modeling. The EPA is responsible for reviewing and approving SIPs, 

which are prepared and submitted to EPA by state environmental agencies.

Transportation Conformity

Transportation conformity is a provision in the CAA, which requires that a conformity 

demonstration be performed by either Federal Highway Administration (FHWA) or Federal 

Transit Administration (FTA) demonstrating that transportation-related highway construction 

will not interfere with achieving NAAQS. The concept of transportation conformity was 

introduced in the Clean Air Act of 1977, but the requirements became substantially more 

rigorous in the Amendments of 1990. The CAA and the Safe, Accountable, Flexible, Efficient 

Transportation Equity Act – A Legacy for Users (SAFETEA-LU), define the framework for 

effective integration of transportation and air quality planning. 

Transportation conformity is a process by which it is determined that on-road mobile 

(highway) source emissions evaluated from the Transportation Improvement Program (TIP) 

and/or Long Range Transportation Plan (LRTP) will not adversely impact air quality in a 

determined area of nonattainment. Federal funding and approval are given to transportation 

activities that are consistent with air quality goals. 

As discussed in more detail in Section 8 of this plan, Delaware revised its 2008 Annual 

PM2.5 Attainment Demonstration SIP in 2012, to address the emission factor changes in the new 

EPA MOVES model, and to establish new budgets for the purposes of addressing transportation 

conformity. Development of the 2008 PM2.5 SIP involved the interagency consultative process 

between EPA, DNREC, Delaware Department of Transportation and local transportation 

agencies such as the Wilmington Area Planning Council (WILMAPCO). WILMAPCO is the 

Metropolitan Planning Organization for New Castle County, Delaware and Cecil County, 

Maryland, and also facilitates the public participation process for stakeholders and citizens in the 

State of Delaware. The 2012 SIP revision to the April 2008 PM2.5 Attainment Demonstration 
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

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SIP was a change to Delaware’s motor vehicle emissions budgets under the PM2.5 annual 

NAAQS, and was submitted to EPA on May 3, 2012.

13

 However, EPA has not completed 

rulemaking on the 2008 SIP and the May 3, 2012 Revision.

Delaware’s SIP contains provisions that are consistent with the Section176(c) conformity 

requirements. In Delaware’s SIP, general conformity requirements are contained in 7 DE 

Admin. Code 1135, Conformity of General Federal Actions to the State Implementation Plans,

(Regulation for General Conformity), which was approved into the Delaware SIP by EPA on 

08/11/2010. (75 FR 48566) Transportation conformity requirements are contained in 7 DE 

Admin. Code 1132, Transportation Conformity, which was approved into the Delaware SIP by 

EPA on 08/11/2010. (75 FR 48566)

6 Maintenance Plan

6.1 EPA Requirements

Section 107(d)(3)(E) of the CAA requires a maintenance plan to meet the requirements of 

Section 175(A). The maintenance plan constitutes a SIP revision and must provide for 

maintenance of the relevant NAAQS in the area for at least 10 years after redesignation, 

including contingency measures to ensure prompt correction of any violation of the NAAQS. 

Section 175(A) further states that the plan shall contain such additional measures, if any, as may 

be necessary to ensure such maintenance. Mobile vehicle emission budgets for transportation 

conformity purposes are also established within the maintenance plans. States must submit a SIP 

revision eight years after the original redesignation request is approved to provide for 

maintenance of the NAAQS for an additional 10 years following the first 10-year period.

EPA provided guidance dated September 4, 1992 on the redesignation request and 

maintenance plan process in the memorandum from John Calcagni, Director, Air Quality 

Management Division to Regional Air Directions entitled Procedures for Processing Requests to 

Redesignate Areas to Attainment (redesignation and maintenance plan guidance). Other 

requirements are provided in 40 CFR 51 Subpart Z, entitled Provisions for Implementation of 

PM2.5 National Ambient Air Quality Standards (PM2.5 implementation rule). Additional 

guidance was received from EPA regional staff in the development of this maintenance plan 

through participation in the Mid-Atlantic Regional Air Management Association (MARAMA) 

PM2.5 workgroup, emails and conference calls, as well as reviewing and providing comments on 

the Technical Support Documents developed through the regional modeling efforts. EPA

requires the following provisions to ensure maintenance of the NAAQS:

 The state must develop an attainment emissions inventory to identify the level of 

emissions in the area which is sufficient to attain the NAAQS.

 A state may generally demonstrate maintenance by showing that future emissions of a 

 

13 This annual maintenance plan SIP revision will establish motor vehicle emission budgets for NOx and primary 

PM2.5 for the interim year 2017, and the final year of the maintenance plan, which is 2025. These budgets are 

adopted from the 2008 PM2.5 SIP revision, submitted to EPA in May, 2012. 
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

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pollutant or its precursors will not exceed the level of the attainment inventory over the 

10-year period following redesignation.

 Once an area has been redesignated, the state must continue to operate an appropriate air 

quality monitoring network in order to verify the area's attainment status.

 The state must ensure that it has the legal authority to implement and enforce all 

measures necessary to attain and maintain the NAAQS. Continued attainment must be 

verified by the state by indicating how maintenance plan progress will be tracked.

 Contingency measures must be available to promptly correct any NAAQS violation. At a 

minimum, the contingency measures must include a requirement that the state will 

implement all measures contained in the nonattainment SIP prior to redesignation. 

6.2 Delaware Approach

The State of Delaware has developed this maintenance plan which meets all of EPA

requirements and demonstrates that because of permanent and enforceable measures, emissions 

over the 10 years following redesignation approval will remain below the 2007 attainment year 

levels while allowing for growth in population and vehicle miles traveled. The period covered 

by this maintenance plan is 2007 through 2025, with an interim year of 2017.

Delaware has developed an emissions inventory in accordance with EPA guidance that 

identifies the level of emissions sufficient to achieve the 1997 PM2.5 NAAQS. This attainment 

inventory consists of the actual 2007 emissions, i.e. a year during the three-year period 

associated with the 2007-2009 monitoring data showing attainment of the 1997 PM2.5 NAAQS. 

The plan includes a demonstration that emissions will remain beneath the 2007 levels for a 10-

year period following redesignation, by keeping in place key elements of the current federal and 

state regulatory programs and putting in place additional controls. 

As discussed in Section 3.5.1, the State of Delaware will continue to operate and 

maintain its air quality monitoring network. Delaware has the legal authority to implement and 

enforce specified measures necessary to attain and maintain the NAAQS.

In addition to maintaining key elements of its regulatory program, the State of Delaware 

will acquire air quality monitoring and source emissions data to track attainment and 

maintenance. The maintenance plan includes contingency measures, as necessary, to promptly 

correct any NAAQS violation that occurs after redesignation of the area. 

The following sections provide detail on each of the above requirements, and the State of 

Delaware approach to meeting each requirement.
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

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7 Attainment Inventory

7.1 EPA Requirements

The State of Delaware must develop an attainment year emissions inventory to identify 

the level of emissions sufficient to achieve the NAAQS. This inventory should be consistent 

with EPA's most recent guidance on emission inventories for nonattainment areas available at the 

time, and should include emissions during the time period associated with the monitoring data 

showing attainment of the 1997 PM2.5 NAAQS. Where a state has made an adequate 

demonstration that air quality has improved as a result of their State Implementation Plan (SIP), 

the attainment inventory will generally be the actual inventory during the time period the area 

attained the standard. The inventory should be based on annual emissions of SO2, NOX, and 

primary PM2.5 in units of tons per year (tpy) during the attainment year.

7.2 Delaware Approach

The State of Delaware developed an attainment year emissions inventory that identifies 

the level of emissions sufficient to achieve the 1997 PM2.5 NAAQS. The attainment inventory 

consists of actual emissions for a year during the three-year period associated with the 

monitoring data showing attainment of the PM2.5 standard, that is, 2007 for the annual NAAQS 

maintenance plan. The 2007 inventory is appropriate to use because it represents the typical 

inventory for the three-year period demonstrating attainment of the standard. The 2007 

inventory is consistent with EPA inventory guidance; is based on annual emissions of SO2, NOX, 

and primary PM2.5 during 2007; and contains a list of sources and emissions in tpy. 

7.3 2007 Attainment Year Inventory

The Delaware DAQ, in conjunction with MARAMA, New Jersey and Pennsylvania DEQs 

prepared a comprehensive emissions inventory for each county in the Philadelphia NAA, 

including point, area, and on-road and off-road mobile sources for primary PM2.5 as well as

precursors of PM2.5 (NOx and SO2) for the year 2007. MARAMA and the Philadelphia NAA air 

control agencies selected 2007 emissions data to represent the “attainment year” since it falls 

within the 3-year period (2007-2009) which demonstrates monitored attainment. Furthermore, 

2007 was planned as the base year for the Ozone Transport Commission’s (OTC) modeling work 

for ozone State Implementation Plans (SIP), and as such has undergone extensive quality 

assurance. 

This inventory is based on actual activity levels. Point source information was compiled 

from 2007 Annual Emissions Reports (AERs) submitted to the Delaware DAQ by emissions 

sources. Area source emissions were calculated using the most recently available methodologies 

and emissions factors from EPA along with activity data (typically population, employment, fuel 

use, etc.) specific to 2007. On-road mobile source emissions were calculated using EPA’s Motor 

Vehicle Emission Simulator (MOVES) model with 2007 vehicle miles traveled (VMT) data

provided by the Delaware Department of Transportation (DelDOT). Off-road mobile source

exhaust emissions, such as those from lawn and garden equipment, agricultural equipment, and 

construction equipment were calculated for 2007 using EPA’s National Mobile Inventory Model 
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

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(NMIM) emissions model. Emissions sources such as commercial marine vessels, aircraft and 

locomotives (MAR) were not included in the NMIM model and were calculated separately. 

Biogenic emissions were not included in these summaries. Details of how the inventory was 

developed can be found in following document: Technical Support Document for the 

Development of the 2007 Emission Inventory for Regional Air Quality Modeling in the Northeast

/ Mid-Atlantic Region. 

Table 7-1 Summarizes the 2007 emissions estimates for the New Castle County portion of 

the Philadelphia NAA.

Table 7-1 2007 New Castle County Emissions (tpy)

Source Sector

2007 Annual Emissions (TPY)

NOx PM25 SO2

Area 1,293 1,207 630

Nonroad MAR 2,825 171 1,027

Nonroad NMIM 1,755 156 91

Onroad MOVES 10,577 324 100

Point EGU 2,865 519 9,119

Point nonEGU 3,770 816 4,261

All Sectors 23,084 3,193 15,228

Note: due to rounding, total tpy may be off by 1 ton. 

8 Maintenance Demonstration

8.1 EPA Requirements 

The 1992 EPA Calcagni Memo14, entitled Procedures for Processing Requests to 

Redesignate Areas to Attainment, discusses how states may demonstrate maintenance of the 

NAAQS by showing that future emissions of a pollutant or its precursors will not exceed the 

level of the attainment inventory. The demonstration should be for a period of 10 years 

following the redesignation. The projected inventory should consider future growth, including 

population and industry. It should also be consistent with the attainment inventory, and it should 

document data inputs and assumptions. All elements of the demonstration should be consistent 

with current EPA guidance. Enforceability through regulations must also be demonstrated.

The Calcagni Memo goes on to say that any assumptions concerning emission rates must 

reflect permanent, enforceable measures. States generally cannot take credit for reductions 

unless there are regulations in place requiring those reductions or the reductions are otherwise 

 

14 http://www.epa.gov/ttn/oarpg/t5/memoranda/redesignmem090492.pdf
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

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shown to be permanent. Therefore, states are expected to maintain the implemented control 

strategy despite redesignation to attainment, unless such measures are shown to be unnecessary 

for maintenance or are replaced with measures that achieve equivalent reductions. Emission 

reductions from source shutdowns can be considered permanent and enforceable to the extent 

that those shutdowns have been reflected in the SIP and all applicable permits have been 

modified accordingly.

8.2 Delaware Approach

A Maintenance Plan must contain a demonstration that the level of emissions projected 

for the ten-year period following redesignation is sufficient to maintain the NAAQS. Because 

Delaware intends to submit this Plan in 2012, and EPA has a maximum of 18 months to 

approve it,15 the EPA approval date for redesignation is expected to be before 2015, and ten 

(10) years after that is 2025. Accordingly, DAQ projected PM2.5, NOx, and SO2 emissions for

2025 to represent the end year of the maintenance plan. DAQ also projected emissions to 2017 

to represent an interim year during the maintenance period. Emissions for the 2017 and 2025 

projection years are compared to emissions levels in 2007 to determine if emissions are

sufficient to maintain the NAAQS during this period, i.e. they must be lower than 2007.

8.2.1 2017 and 2025 Projection Inventories

As was done with the 2007 attainment year, 2017 and 2025 projection inventories 

were develop through the MARAMA regional planning process. For 2025 emission 

projections, the emission methodologies and growth factors can be found in the Technical 

Support Document for the Development of the 2025 Emission Inventory for PM2.5 

Nonattainment Counties in the MANE-VU Region, January 2012 (MARAMA 2025 TSD). 

For 2017 emission projections, the emission methodologies and growth factors can be found 

in the Technical Support Document for the Development of the 2013/2017/2020 Emission 

Inventories for Regional Air Quality Modeling in the Northeast/Mid-Atlantic Region

(MARAMA 2017 TSD). 

New Castle County point and area source emissions for 2017 and 2025 were estimated 

using the 2007 attainment inventory and growth/control factors appropriate for each source 

category. EGU emissions were projected using Department of Energy 2011 Annual Energy 

Outlook growth factors, with control factors applied due to Delaware’s EGU regulations (7 DE 

Admin Code 1146 Electric Generating Unit Multi-Pollutant Regulation, and 7 DE Admin 

Code 1148 Control of Stationary Combustion Turbine Electric Generating Unit Emissions).

Off-road emissions projections were developed using the growth factors contained in EPA’s

NMIM model. 

For mobile budget purposes Delaware is using the 2012 mobile emissions from its 

PM2.5 Attainment Demonstration Revision, submitted to EPA on May 3, 2012. Delaware 

used 2012 mobile emissions in lieu of projected mobile emissions because:

 

15 CAA Section 107 (d)(3)(D)
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

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1. They are based on the most up-to-date mobile source assumptions available.

2. 2012 emission budgets are 41% and 39% less than the onroad NOx and PM2.5 found in 

the 2007 attainment year. (see table 8-2 and 8-3)

3. Additional reductions are not necessary in the context of this maintenance plan.

The 2012 emission inventory modeling of the on-road mobile source sector was 

performed by WRA Associates LLP, Wilmington, Delaware, under contract to DelDOT with 

technical support from the Division of Air Quality (DAQ) staff. The on-road mobile sources 

cover all highway vehicles including passenger cars, light-duty trucks, sport utility vehicles, 

heavy-duty trucks, buses, and motorcycles, which travel on Delaware’s roadways in 2012.

Delaware Department of Transportation (DelDOT) staff provided the vehicle miles traveled

(VMT) on Delaware’s roadways. DAQ staff also evaluated all information concerning control 

measures that would be effective in 2012. With the vehicle mix data and control information, 

the EPA’s MOVES model was used to generate monthly emissions for PM2.5, oxides of 

nitrogen and SO2. After QC/QA reviews and revision by DAQ staff the emission data were 

finalized, and included in the final inventory. The on-road mobile source controls for New 

Castle County in the input files for the 2012 MOVES model runs include the following: 

1. Low enhanced I/M program of model years 1968 through 1995

2. On-Board Diagnostic checks of model years 1996 and newer.

3. National Low Emission Vehicle program, 

4. Tier 2 emission standards/low sulfur rule.

5. Heavy Duty Diesel Rule/low Sulfur rule.

Table 8-1 provides a comparison of emissions for the years 2007, 2017 and 2025. The

table demonstrates that the level of emissions projected through the maintenance period are

less than emissions estimated for the attainment year and are, therefore, sufficient to maintain 

the PM2.5 NAAQS. Tables 8-2 through 8-4 show NOx, PM2.5 and SO2 reductions (tpy) 

between 2007 and 2017 and 2025. The tables also provide the percent reduction of NOx, 

PM2.5 and SO2 by sector for those same years. It is readily apparent from these tables that SO2

and NOx emissions are expected to decrease significantly between 2007 and 2025, i.e. 40% 

and 54% for NOx and SO2, respectively. PM2.5 decreases less significantly (14%). Projected 

emissions of those pollutants for the mid-point year of 2017 are also significantly less than 

their respective emissions levels in 2007. Based on these emissions trends it is expected that 

air quality will continue to meet the PM2.5 NAAQS throughout the maintenance period.
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

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Table 8-1 Comparison of emissions for the years 2007, 2017 and 2025

SECTOR

NOX PM2.5 SO2

2007 2017 2025 2007 2017 2025 2007 2017 2025

Area 1,293 1,295 1,296 1,207 1,235 1,310 630 521 469

Nonroad MAR 2,825 1,810 1,279 171 61 44 1,027 112 37

Nonroad-NMIM 1,755 997 837 156 106 103 91 2 3

Onroad MOVES 10,577 6,273 6,273 324 199 199 100 98 98

Point – EGU 2,865 1,698 1,758 519 502 520 9,119 2,419 2,572

Point - nonEGU 3,770 2,402 2,355 816 742 716 4,261 3,843 3,780

All Sectors 23,084 14,475 13,797 3,193 2,844 2,893 15,228 6,995 6,958

Table 8-2 Reductions and % Change of NOx emissions for the years 2007, 2017 and 2025

NOx Reduction (tpy) Change (%) Reduction (tpy) Change (%)

Sector 2007 2017 2025 2007-2017 2007 to 2017 2007 to 2025 2007 to 2025

Area 1,293 1,295 1,296 -3 0.2% -3 0.2%

Nonroad MAR 2,825 1,810 1,279 1,015 -35.9% 1,546 -54.7%

Nonroad-NMIM 1,755 997 837 758 -43.2% 918 -52.3%

Onroad MOVES 10,577 6,273 6,273 4,304 -40.7% 4,304 -40.7%

Point – EGU 2,865 1,698 1,758 1,167 -40.7% 1,107 -38.7%

Point - nonEGU 3,770 2,402 2,355 1,368 -36.3% 1,415 -37.5%

Total tpy 23,084 14,475 13,797 8,609 -37% 9,287 -40%
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

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Table 8-3 Reductions and % Change of PM2.5 emissions for the years 2007, 2017 and 2025

PM2.5 Reduction (tpy) Change (%) Reduction (tpy) Change (%)

Sector 2007 2017 2025 2007 to 2017 2007-2017 2007 to 2025 2007 to 

2025

Area 1,207 1,235 1,310 -28 2.3% -103 8.5%

Nonroad MAR 171 61 44 110 -64.2% 126 -74.0%

Nonroad-NMIM 156 106 103 51 -32.5% 53 -34.0%

Onroad MOVES 324 199 199 125 -38.6% 125 -38.6%

Point – EGU 519 502 520 17 -3.2% -1 0.2%

Point - nonEGU 816 742 716 75 -9.1% 100 -12.2%

Total tpy 3,193 2,844 2,893 349 -11% 301 -9%

Table 8-4 Reductions and % Change of SO2 emissions for the years 2007, 2017 and 2025

SO2 Reduction (tpy) Change (%) Reduction (tpy) Change (%)

Sector 2007 2017 2025 2007 to 2017 2007-2017 2007 to 2025 2007 to 2025

Area 630 521 469 109 -17.4% 161 -25.6%

Nonroad MAR 1,027 112 37 915 -89.1% 990 -96.4%

Nonroad-NMIM 91 2 3 89 -97.3% 88 -96.5%

Onroad MOVES 100 98 98 2 2.4% 2 2.4%

Point - EGU 9,119 2,419 2,572 6,700 -73.5% 6,547 -71.8%

Point - nonEGU 4,261 3,843 3,780 418 -9.8% 482 -11.3%

Total tpy 15,228 6,995 6,958 8,234 -54% 8,271 -54%

8.2.2 2017 and 2025 Mobile Source Emissions Budgets

Transportation conformity is a way to ensure that federal funding and approval are given 

to those transportation activities that are consistent with air quality goals. Transportation 

activities should not worsen air quality or interfere with an area’s continued compliance in 

regards to the 1997 PM2.5 NAAQS. The federal transportation conformity rule is codified in 40 

CFR Part 93, subpart a, entitled Determining Conformity of Federal Actions to State or Federal 

Implementation Plans (transportation conformity rule). This rule applies to areas designated as 

nonattainment for one or more NAAQS or that have been redesignated to attainment with 
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

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federally approved air quality maintenance plans. The responsible transportation planning 

entities for the New Castle County, Delaware potion of the Philadelphia 1997 PM2.5 NAA is the 

Delaware Department of Transportation (DelDOT) and the Wilmington Area Planning Council 

(WILMAPCO). In the transportation conformity process, overall emissions estimates by 

analysis year that take into account future traffic activity and projects expected to be completed 

are compared to a base year, a no build scenario, or emission budgets. Emission budgets are 

used in this maintenance plan determination only if EPA has approved or found adequate 

emissions budgets that have been submitted as a SIP revision. 

The purpose of this section is to describe and establish the New Castle County motor

vehicle emissions budgets associated with the PM2.5 Maintenance Plan SIP. Annual motor

vehicle emissions budgets are being proposed for the final year of the Maintenance Plan, 2025. 

The Maintenance Plan also includes motor vehicle emissions budgets for the interim year 2017.

Delaware is establishing mobile budgets for PM2.5 and NOx.16 Ammonia and volatile 

organic compounds (VOC) are precursors; however, they are not considered significant overall 

contributors to PM2.5 air quality issues, as noted in the PM2.5 implementation rule at 40 CFR 

51.1002(c)(3). For other pollutants such as SO2, the highway contribution to those emissions 

may be insignificant. In that case, the transportation conformity rule allows such pollutants and 

precursors to be exempt from conformity analysis under certain circumstances:

40 CFR93.109 (k) Areas with insignificant motor vehicle emission

Notwithstanding the other paragraphs in this section, an area is not required to satisfy 

regional emissions analysis for §93.118 and/or §93.119 for a given pollutant/precursor 

and NAAQS, if EPA finds through the adequacy or approval process that a SIP 

demonstrates that regional motor vehicle emissions are an insignificant contributor to 

the air quality problem for that pollutant/precursor and NAAQS. The SIP would have to 

demonstrate that it would be unreasonable to expect that such an area would experience

enough motor vehicle emissions growth in that pollutant/precursor for a NAAQS 

violation to occur. Such a finding would be based on a number of factors, including the 

percentage of motor vehicle emissions in the context of the total SIP inventory, the 

current state of air quality as determined by monitoring data for that NAAQS, the 

absence of SIP motor vehicle control measures, and historical trends and future 

projections of the growth of motor vehicle emissions.

A motor vehicle emissions budget is that portion of the total allowable emissions 

allocated to highway and transit vehicle use that are defined in the SIP for a certain year. The

rules governing transportation conformity require certain transportation activities to be consistent 

with motor vehicle emissions budgets contained in control strategy implementation plans (40 

CFR § 93.118). Section 93.101 of the rule defines a “control strategy [State] implementation 

 

16 As discussed in Delaware’s 2008 Annual PM2.5 Attainment Demonstration, and revised in Delaware’s Final

Revision to Delaware’s 2008 State Implementation Plan for Attainment of the PM2.5 Annual National Ambient Air 

Quality Standard - Attainment Demonstration, submitted to EPA May 3, 2012. 
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

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plan revision” as a “plan which contains specific strategies for controlling the emissions and 

reducing ambient levels of pollutants in order to satisfy CAA requirements of reasonable further

progress and attainment.” In order to demonstrate conformity to the motor vehicle emissions 

budget, emissions from the implementation of a transportation plan or a transportation 

improvement program (TIP) must be less than or equal to the budget level (40 CFR § 93.118(a)).

The 2012 budgets established in Delaware’s May 3, 2012 PM2.5 Attainment 

Demonstration SIP revision (submitted to EPA on 5/3/2012) represent a level of mobile 

emissions lower than what existed during the years attainment was reached (i.e., 2007-2009 and 

2008-2010). Further, mobile reductions are not necessary to demonstrate maintenance, and the 

2025 NOx and PM2.5 emissions are well below 2007 levels. As such, there is no need to develop 

new mobile budgets at this time. Therefore, Delaware proposes to use existing 2012 budgets for 

the 2017 interim year, as well as the end year, 2025.

17

Table 8-5 summarizes the budgets for each relevant year.

Table 8-5 New Castle County Maintenance Plan On-Road Mobile Source Emissions 

Budgets

Year NOX On-Road

Emissions (tpy)

PM2.5 On-Road 

Emissions (tpy)

2012 Attainment SIP 

Revision – Mobile Budgets 6,273 199

2017 Interim Budget 6,273 199

2025 Final Budget 6,273 199

MOVES model 2012 inputs and outputs for NOx and PM2.5 may be found in Delaware’s 

final revision to the 2008 State Implementation Plan for Attainment of the PM2.5 Annual 

National Ambient Air Quality Standard - Attainment Demonstration. That SIP revision was 

submitted to EPA on May 3, 2012. 

8.2.3 Control Measures for Maintenance of Good Air Quality

Point, area, non-road and on-road emission projections for 2017 and 2025 include a 

variety of control strategies that will continue to reduce emissions of PM2.5, NOX, and SO2 in the 

future years. The sections below describe the major control programs in each category. Many of 

these programs are federal programs that are enforced on a regional or national level. In cases 

where the programs are delegated programs or state programs, EPA has approved these programs 

into the Delaware SIP. The State of Delaware commits to continue to implement and enforce 

 

17 DAQ may require new budgets should the Philadelphia maintenance area lapse into nonattainment (see Section 

10)
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

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these programs as appropriate to ensure that reductions assumed in 2017 and 2025 will be 

achieved. 

Tables 8-2 through 8-4 show that that projected 2007 to 2025 reductions are 9,287 tpy for 

NOx, 301 tpy for PM2.5 and 8,271 tpy for SO2. In terms of percent reductions, this equates to 

40%, 9% and 54% reductions of NOx, PM2.5 and SO2, respectively. The same tables show 

projections from 2007 to the 2017 interim year. 2007-2017 reductions are 8,609 tpy for NOx, 

349 tpy for PM2.5 and 8,234 for SO2. In terms of percent reductions, this equates to 37%, 11% 

and 54% reductions of NOx, PM2.5 and SO2, respectively.

 

However, not all of these reductions are due to control measures. Projected emissions 

can be higher or lower due to growth factors alone, or in combination with controls (assuming 

controls exist for a certain source category). DAQ calculated reductions that will occur after 

2007 due only to control measures, (no growth), for EGUs, non-EGU point sources, area and 

“marine, aircraft and locomotive” (MAR) sources. Because onroad and non-MAR off-road 

sources are estimated using EPA models (MOVES and NMIM), and inherently include growth in 

the form of fleet turnover, equipment turnover, ex. lawnmowers, etc., it is not feasible to break 

out onroad and non-MAR off-road reductions due exclusively to controls. The same rationale 

applies to residential wood combustion, which also relied on an EPA model. Table 8-6 shows 

the reduction due to controls and the control measure by source sector. 

Looking at Table 8-6, it is evident that all but the area source sectors had significant 

decreases for NOx, SO2 and/or PM2.5 due to control measures. 

Table 8-6 2007 to 2025 Emission Reductions due to Control Measures

Source Sector NOx PM2.5 SO2

EGUs

DE Admin Code 1146 (Multi-Pollutant Regulation) 1,240.8 10.5 6,562.4

nonEGU

Delaware City Refinery NOx CAP (1650 tpy) post-2015 1,157.26 0.00 0.00

Reciprocating Internal Combustion Engines -

Maximum Achievable Control Technology,

(RICE MACT) (76 FR 12863)

0.02 0.08 0.00

Chrysler Plant Shutdown /unit shutdown 6.50 0.89 16.64

AREA

RICE MACT 42.51 0.30 0.00

EPA New Source Performance Standards for Woodstoves (NSPS). These 

standards are codified at 40 CFR part 60, subpart AAA. The final standards 

were promulgated in 1988 (53 FR 5860).

5.00 76.64 0.84

Nonroad (NMIM model) 918 53 88
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

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ONROAD (MOVES model) 4,304 125 2

Marine Vessels, Aircraft and Locomotives (MAR)

Control of Emissions of Air Pollution From Locomotive Engines and Marine 

Compression-Ignition Engines Less Than 30 Liters per Cylinder; Republication; 

Final Rule. (73 FR 37096)

933 37 152

Control of Emissions From New Marine Compression-Ignition Engines at or 

Above 30 Liters per Cylinder(75 FR 22895) 631 90 836

TOTALS 9,241 394 7,660

8.2.4 Delaware-specific NOx, PM2.5 or SO2 Control Measures (Effective Post 2007)

 7 DE Admin. Code 1146, EGUs, Electric Generating Unit (EGU) Multi-Pollutant 

Regulation, SO2 and NOX emission control, State-wide, Effective December 2006,

18

approved into Delaware’s SIP August 28, 2008 (73 FR 50723), March 16, 2010 (75 FR 

12449), and August 11, 2010 (75 FR 48566).

 7 DE Admin. Code 1142, Section 2, Control of NOX Emissions from Industrial Boilers 

and Process Heaters at Petroleum Refineries, NOX emission control, New Castle County, 

Effective July 2007; approved into Delaware’s SIP June 4, 2010 (75 FR 31711) and 

August 11, 2010 (75 FR 48566); revisions approved May 15, 2012 (77 FR 28489).

 7 DE Admin. Code 1148, Control of Stationary Combustion Turbine Electric Generating 

Unit Emissions, approved into Delaware’s SIP on November 10, 2008 (73 FR 66554) and 

August 11, 2010 (75 FR 48566).

EGU reductions

EGUs are a subset of point source emissions and include the following New Castle County 

facilities: 

 Conectiv Delmarva Generation-Del City

 Conectiv Delmarva Generation-West Substation

 Conectiv Delmarva Generation-Edge Moor

 Conectiv Delmarva Generation-Christiana

 Conectiv Delmarva Generation-Hay Road

Of these facilities, Edge Moor is the only one which had coal-burning units and residual 

oil in 2007. The rest used either natural gas or distillate oil, and thus had small PM2.5 and SO2

 

18 Although effective in 2006, NOx controls were not required until January 1, 2009 and SO2 controls were not 

required until January 1, 2012. 
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

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emissions in 2007 and are projected to have small emissions of PM2.5 and SO2 emissions in 

2025. Consequently, Edge Moor was the largest EGU emitter, e.g. its 2007 emissions 

represented 90%, 92% and 99.9% of NOx, PM2.5 and SO2, respectively for all New Castle 

County EGUs. Because Units 3 and 4 were coal-fired in 2007, and Unit 5 operates primarily on 

residual oil, the Edge Moor facility is subject to 7 DE Admin. Code 1146, EGU Multi-pollutant 

Regulation, 7 DE Admin. Code 1146, is a non-trading program/regulation that was established 

primarily as a measure to aid in the attainment of the ozone and fine particulate matter ambient 

air quality standards. 

7 DE Admin. Code 1146 will reduce 2007 EGU emissions by 1,241 tpy NOx, 10.5 tpy 

PM2.5 and 6,562 tpy SO2 in 2025 (see Table 8-7). PM2.5 emission controls are not directly 

regulated under 7 DE Admin. Code 1146, but are a co-benefit of the 0.5% by weight low-sulfur 

residual oil limit on Unit 5. 

Non-EGU reductions

 Delaware Source Shutdowns (post-2007)

The Chrysler automotive plant ceased commercial operation in January, 2009. However, 

only a 25% reduction was applied, since Chrysler maintains 50% of the emission credits 

and the Delaware Economic Development Office retains the remaining 25%.

Delaware Onroad 

In additional to the federal Tier 1 and 2 programs, NLEV, and the federal 2007 heavy 

duty highway rule, Delaware has instituted Enhanced Vehicle Emissions Inspection And 

Maintenance (enhanced I/M) requirements in New Castle County. The requirements involve 

mandating regional vehicle emission I/M programs that are stricter than basic programs, as 

required under §§182 and 202 of the CAA. Before 1994, basic automobile emissions testing 

checked only tailpipe emissions while idling and sometimes at 2,500 rpm. Enhanced I/M 

procedures include the use of On Board Diagnostic (OBD) system evaluations. The OBD 

evaluations provide a more complete inspection, checking for excess evaporative emissions and 

other issues that might affect emissions from the vehicle. Delaware’s enhanced I/M program 

was approved into the Delaware SIP by EPA on September 30, 1999 (64 FR 52657). Revisions 

to the enhanced I/M program were approved by EPA on 11/26/2003 (68 FR 228). 

8.2.5 Federal Control Measures (Effective or Phased-in Post 2007)

Federal control measures that are either effective or phased in after 2007 are the same as 

those discussed in Section 4.3.2. Note that the Woodstove NSPS and many of the nonroad and 

onroad federal control measures have effective dates prior to, during, or after 2007. However, 

other than fuel standards; all of the measures are phased in over many years through fleet or 

equipment “turnover.” For example, in the case of nonroad sources, fleet turnover includes sales 

of new engines replacing older ones over the years. Therefore, it is expected that reductions will 

continue well past the 2007 attainment year.
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

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8.2.6 Future Emissions Reductions Programs 

Delaware 

New Delaware regulations will reduce emissions of NOx, PM2.5 and SO2 even further, 

although these rules are not yet finalized and therefore were not considered in the 2017 and 2025 

estimates included in this document. Measures under development or consideration are:

 Edge Moor Power Plant (fuel switch from coal to natural gas)

 Low-sulfur fuels – statewide

 

Federal

Three new federal regulations may reduce emissions of SO2 even further. These rules 

were not considered in the 2017 and 2025 estimates included in this document. However, these 

rules and the new SO2 NAAQS each should facilitate significant further reductions, both within 

and outside the Philadelphia maintenance area.

 Mercury and Air Toxics Rule: On March 16, 2011, EPA proposed the Mercury and Air 

Toxics Rule to reduce emissions of toxic air pollutants from new and existing coal and 

oil-fired EGUs. The proposed rule would establish numerical emission limits for 

hydrogen chloride (HCl) as a surrogate for toxic acid gases, or alternative standards for 

SO2. EPA estimates that this rule would affect approximately 1,200 coal-fired units 

nationwide and would reduce SO2 emissions from power plants by 55%. The final rule is 

expected to be published in 2012 so that existing sources may be required to demonstrate 

compliance with applicable standards by 2015. National Emission Standards for 

Hazardous Air Pollutants From Coal and Oil-Fired Electric Utility Steam Generating 

Units and Standards of Performance for Fossil-Fuel-Fired Electric Utility, IndustrialCommercial-Institutional, and Small Industrial-Commercial-Institutional Steam 

Generating Units, Final Rule published February 16, 2012 (77 FR 9304); Correction 

published April 19, 2012 (77 FR 23399).

19

 2010 SO2 NAAQS: On June 2, 2010, EPA strengthened the primary NAAQS for SO2 by 

revising the primary SO2 standard to 75 ppb averaged over one hour. This short term 

standard is significantly more stringent than the revoked standards of 140 ppb averaged 

over 24 hours and 30 ppb averaged over a year. Under the new standard’s proposed 

guidance, facilities emitting more than 100 tpy of SO2, many of which are EGUs, will be 

required to demonstrate compliance with the standard no later than 2017. 

 Industrial/Commercial/Institutional (ICI) Boiler Maximum Achievable Control 

Technology (MACT) Standard: EPA finalized the revised ICI Boiler MACT on February 

21, 2011, although portions of the rule are under reconsideration. EPA estimates that 

 

19 This rule is under reconsideration. EPA expects to complete ruling-making in March, 2013 (letter from Gina 

McCarthy, EPA to Patricia T. Barmeyer. July 20, 2012)
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

51

implementation of the revised rulemaking will reduce emissions nationwide from major 

source boilers and process heaters by 47,000 tpy of PM, 440,000 tpy of SO2, and 7,000 

tpy of VOCs. 

 Tier 4 Non-Road Diesel Engine Standards: On May 11, 2004, the EPA signed the final 

rule introducing Tier 4 emission standards, which are being phased-in over the period of 

2008-2015 [69 FR 38957-39273, 29 Jun 2004]. The Tier 4 standards require that 

emissions of PM and NOx be further reduced by about 90%. Such emission reductions 

will be achieved through the use of control technologies including advanced exhaust gas 

after-treatment. 

8.2.7 Controls to Remain in Effect

Delaware will maintain all of the control measures listed in this Section to ensure 

maintenance of the annual PM2.5 NAAQS. Any revisions to the control measures included as 

part of this maintenance plan will be submitted as a SIP revision to EPA for approval, and will be

accompanied by a showing that such changes will not interfere with maintenance of the NAAQS. 

The Delaware DAQ has the necessary resources to enforce any violations of its rules or permit 

provisions. After redesignation to attainment Delaware intends to continue enforcing all rules 

that relate to the emissions of primary PM2.5 and precursors to secondary PM2.5 which may 

impact New Castle County ambient PM2.5 concentrations.

Although Delaware believes that control of organic compounds and ammonia may help 

improve PM air quality, reductions from the control of organics or ammonia, have not been 

relied upon in this maintenance plan, consistent with the PM2.5 Implementation Rule.

9 Verify Continued Attainment

9.1 EPA Requirements

States must ensure that they have the legal authority to implement and enforce all 

measures necessary to attain and maintain the NAAQS. Sections 110(a)(2)(B) and (F) of the 

CAA suggest that one such measure is the acquisition of air quality and source emission data to 

demonstrate attainment and maintenance. 

9.2 Delaware Approach

The State of Delaware has the legal authority to implement and enforce specified 

measures necessary to attain and maintain the 1997 annual NAAQS. In addition to maintaining 

key elements of its regulatory program in place in Delaware’s SIP, Delaware will acquire 

ambient monitoring and source emission data to track attainment and maintenance as described 

in Sections 3 and 7. Delaware will also track the progress of the maintenance demonstration by 

periodically updating the emissions inventory as required by the Annual Air Emissions 

Reporting Requirements Rule, or as required by federal regulation during the maintenance plan 

period. This includes developing annual inventories for major point sources and a 

comprehensive periodic inventory covering all source categories every three years. Tracking 
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

52

will include the evaluation of annual and periodic evaluations for any significant emission 

increases above the 2007 attainment year levels. 

10 Contingency Measures 

10.1 EPA Requirements 

Section 175(A) of the CAA specifies the requirements for Maintenance Plans, including 

provisions for contingency measures that will be implemented if violations of the annual PM2.5

NAAQS are measured after redesignation to attainment. A list of potential contingency

measures that would be implemented in such an event should also be included in the

Maintenance Plan. Finally, the plan should provide a commitment to submit a revised 

Maintenance Plan eight years after redesignation to ensure continued maintenance for the next 

ten-year maintenance period.

Contingency measures are intended to provide further emissions reductions in the event 

that violations of the annual PM2.5 NAAQS occur after redesignation to attainment. While these

measures do not need to be fully adopted by the State of Delaware prior to the occurrence of

NAAQS violations, the contingency plan should ensure that the contingency measures are

adopted expeditiously once they are triggered. The Maintenance Plan must identify the triggers 

that determine when contingency measures will be adopted, and the measures that the state will 

consider. It should also include a schedule and procedures for adoption and implementation, 

and a specific time limit for action. Specific triggers that would put the plan into motion must be 

identified. This plan is considered to be an enforceable part of the SIP and should ensure that the 

contingency measures are adopted explicitly once they are triggered.

10.2 Delaware Approach

Consistent with this plan, Delaware agrees to adopt and implement the necessary

corrective actions in the event that violations of the annual PM2.5 NAAQS occur within the 

Philadelphia maintenance area after its redesignation to attainment.20 As described in Section 5 

of this report, EPA and Delaware have adopted and are continuing to implement a range of

control measures that will greatly reduce precursor emissions locally, statewide and nationwide. 

Delaware commits to continue to implement the identified statewide and local control measures. 

The Delaware DAQ anticipates that post-2007 emissions reductions will be sufficient to mitigate

exceedances or violations of the annual PM2.5 NAAQS that may occur in the coming years 

without further regulatory action. However, in the event of a future violation or exceedance of 

the annual PM2.5 NAAQS, the Delaware DAQ will use the following triggers (determination of 

when to start an action) and perform the following actions in accordance with the described 

schedule, as its contingency plan:

 

20 NJ, DE and PA are each submitting their own redesignation requests and maintenance plans. After each State’s 

Plans are approved by EPA, the Philadelphia NAA will be re-defined as the Philadelphia Maintenance Area. It is 

also possible that a portion of the area may be redesignated to attainment (i.e., a maintenance area) and a portion 

may still be nonattainment. Therefore, for the purposes of this maintenance plan, the “Philadelphia Maintenance 

Area” also includes any areas of the Philadelphia NAA that have not been redesignated to attainment. 
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

53

1. Warning Level Response (one or both of the following events occur): 

a. A warning level response shall be prompted whenever the annual mean PM2.5

concentration of 15.1 μg/m3or greater occurs at any monitoring site in a single 

calendar year within the Philadelphia maintenance area.

b. The New Castle County, Delaware maintenance area total PM2.5, NOx and SO2

emissions increase more than 10% above the levels in the 2007 attainment year 

emissions inventory. 

2. Action Level Response

An action level response shall be prompted whenever a two-year average of the annual 

mean PM2.5 concentration is 15.1 μg/m3or greater occurs at any monitoring site within the 

Philadelphia maintenance area. A violation of the standard (three-year average of 15.1 μg/m3

or greater) shall also prompt an action level response. 

3. Study and data analysis 

In order to select appropriate corrective measures for warning or action level triggers, the 

Delaware DAQ will work independently, or in conjunction with the States of Pennsylvania and 

New Jersey, and the City of Philadelphia to conduct a comprehensive study to determine the 

causes of the violation and the control measures necessary to mitigate the problem. This analysis 

may include all or some of the following factors as necessary, to determine the cause of the 

exceedance, emissions increase or violation:

• The location and severity of the ambient PM2.5 exceedances;

• The weather patterns contributing to the elevated PM2.5 levels;

• Potential contributing emissions sources;

• The geographic applicability of possible contingency measures;

• Emissions trends, including timeliness of implementation of scheduled control 

measures;

• Current and recently identified control technologies; 

• Air quality contributions from outside the maintenance area;

• Activity data for relevant sources;

• Information on any unusual events (e.g. forest fires, natural disasters), transport from out 

of state sources;

• Violation of an existing rule or permit, and;

• Any other related data to try to determine the cause of the violation. 
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54

The study will evaluate whether the trend, if any, is likely to continue and if so, the 

control measures necessary to reverse the trend taking into consideration ease and timing for 

implementation as well as economic and social considerations. In the event that the trigger is not 

found to be due to an exceptional event, malfunction, or noncompliance with a permit condition 

or rule requirement, Delaware DAQ will work with the States of Pennsylvania and New Jersey, 

and the City of Philadelphia as necessary, to determine additional control measures needed to 

assure future attainment of the 1997 annual PM2.5 NAAQS.

Based on the results of the analysis, contingency measures will be selected from those 

listed below, or from any other measure deemed appropriate and effective at the time the 

selection is made. However, if a new measure or control is already promulgated and scheduled

to be implemented at the federal or state level at such time after the exceedance, and that 

measure or control is determined to be sufficient to address the upward trend in air quality, 

additional local measures may be unnecessary. The selection between measures will be based 

upon cost-effectiveness, emissions reduction potential, ease and timing of implementation, and 

other appropriate factors. Delaware will submit to EPA an analysis to demonstrate the proposed 

measures are adequate to return the area to attainment.

Adoption of any additional control measures will be subject to the necessary 

administrative and legal processes. The Delaware DAQ will solicit input from all interested and 

affected persons in the area prior to selecting appropriate control measures. No contingency 

measure shall be implemented without providing the opportunity for full public participation 

during which the relative costs and benefits of individual measures, at the time they are under 

consideration, can be fully evaluated. This process will include publication of notices, an 

opportunity for public hearing, and other measures required by Delaware law. 

4. Timing of contingency measure implementation

A timeline for the development of NOx, PM2.5 and/or SO2 regulations or permit 

conditions follows. This schedule initiates with certification of ambient air quality monitoring 

data indicating a violation of the annual PM2.5 NAAQS:

a. Warning Level Response

Should a warning level response be triggered, measures that can be implemented in a 

short time will be selected in order to be in place within 18 months from the close of 

the calendar year that prompted the warning level.

b. Action Level Response 

Should an action level response be triggered, implementation of necessary controls 

measures will take place as expeditiously as possible, but in no event later than 18 

months after the Delaware DAQ makes a determination, based on quality-assured 

ambient data, that a violation of the NAAQS has occurred.
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55

Table 10-1 Schedule for Permit Revisions or Rule Revisions for Contingency Measures21

Identify and quantify the emissions reductions expected to result in the future 

from existing and future state and federal regulatory programs. 3 months

Use the best available air quality modeling to evaluate the air quality 

improvement expected to result in the Philadelphia MA from the programs and 

emissions reductions identified in 10.2.5 of this document.

6 months

Draft any needed permit conditions or SIP regulations. 3 months

Complete rulemaking or permit revision process and submit to EPA. 6 months

Completion no later than: 18 months

5. List of Potential Contingency Measures

 Lower particulate limits for No. 6 fuel oil-fired boilers.

 Working with the local metropolitan planning agencies to implement transportation 

control measures such as: traffic flow improvements, transit improvements, trip 

reduction programs, arterial and signal improvement projects, bicycle projects, or other 

new transportation measures.

 Low-sulfur distillate and residual fuels.

 Additional PM2.5 controls for EGUs and large industrial boilers burning fuels other than 

distillate fuel or natural gas. 

 Vehicle inspection and maintenance program enhancements, addition of diesel vehicles, 

etc.).

 Alternative fuel and additional diesel retrofit programs for fleet vehicle operations.

 Require NOx or SO2 emission offsets for new and modified major sources.

 Increase the ratio of emission offsets required for new sources.

 Require NOx or SO2 controls on new minor sources (less than 100 tons).

 Require increased recovery efficiency at sulfur recovery plants.

 Broader geographic applicability of existing measures.

 

21 This schedule initiates with certification of ambient air quality monitoring data indicating a violation of the 1997 

annual PM2.5 NAAQS. An action level response is triggered by a violation as well as when a two-year average of 

the annual PM2.5 concentration is 15.1 μg/m3or greater.
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11 Other Delaware Commitments 

11.1 Commitment to Revise Plan

Delaware DAQ commits to submit a second 10-year Maintenance Plan eight years after

redesignation to attainment, as required by Section 175(A)(b) of the CAA. The Maintenance

Plan revision is intended to ensure continued attainment of the annual PM2.5 NAAQS for an 

additional ten-year period.

11.2 Public Participation

In accordance with Section 110(a)(2) of the CAA, Delaware is required to have a public 

comment period and provide the opportunity for a public hearing on this Maintenance Plan prior

to adoption. Public participation in the Delaware SIP process is required by Delaware law22 as 

follows: 

 Notice of availability of the SIP document and the time and date of the public hearing are 

published as a Legal Notice in the News Journal and Delaware State News.

 A public hearing is required for the adoption of all Delaware State Implementation Plans 

and Regulations, and was held on October 23, 2012. 

 A 30-day public comment period was provided before the public hearing to receive 

comments on the Maintenance Plan. A summary of any comments received and 

Delaware DAQ’s responses is included with this SIP submittal to the EPA.

 The Legal Notices, Comments and other documentation as required by EPA and 

Delaware Law and DNREC policies will also be submitted to the EPA.

12 Conclusions

The Philadelphia nonattainment area has attained the 1997 annual PM2.5 NAAQS and has 

complied with the applicable provisions of the CAA required of the PM2.5 NAAQS. Delaware 

demonstrated that the Philadelphia NAA has attained the 1997 annual PM2.5 NAAQS and that 

the air quality improvements are due to permanent and enforceable control measures. 

The Delaware DAQ has prepared a Maintenance Plan that meets the requirement of

175A of the Clean Air Act. This Maintenance Plan provides for the continued attainment of the

1997 annual PM2.5 NAAQS for a period of at least ten years after EPA has formally redesignated 

the area to attainment. This Maintenance Plan provides adequate contingency measures for

 

22 TITLE 29, General Regulations For State Agencies, Chapter 101. Administrative Procedures, Subchapter 

II, Agency Regulations.
Delaware Redesignation Request and Maintenance Plan – 1997 Annual PM2.5 NAAQS

57

potential, additional emissions reductions in the event that future violations of the 1997 annual 

PM2.5 NAAQS are observed in the area. 

Delaware has performed an analysis that shows the air quality improvements are due to 

permanent and enforceable measures and that additional significant regional NOx and SO2

reductions following implementation of federal and state measures will ensure continued 

compliance (maintenance), with the standard. Furthermore, emission projections in the 

Maintenance Plan indicate that NOx, PM2.5 and SO2 emissions will continue to decline, ensuring 

that the area continues to maintain compliance with the standard and provide for an increased 

margin of safety.

The Delaware DAQ has prepared a comprehensive emissions inventory of PM2.5 and its 

precursors for the base year, 2002 to meet CAA 172(c)(3) requirements, as submitted to EPA 

April, 5 2008, in the Delaware State Implementation Plan for Attainment of the PM2.5 Annual 

National Ambient Air Quality Standard - Attainment Demonstration.

The Delaware DAQ has prepared a comprehensive emissions inventory of PM2.5 and its 

precursors for the attainment year (2007), and has prepared projections of the emissions 

inventory to 2017 and 2025. These emissions projections indicate that emissions levels in the

New Castle portion of the Philadelphia NAA will continue to remain much lower than emissions 

from the attainment year 2007 levels, thereby maintaining the PM2.5 NAAQS in future years.23 

The Delaware DAQ commits to continue to operate an appropriate air quality monitoring

network to verify the maintenance of the attainment status once the area has been redesignated. 

The Delaware DAQ has the legal authority to implement and enforce all control measures.

Finally, the Delaware PM2.5 Maintenance Plan includes year 2017 and 2025 on-road 

motor vehicle emissions budgets for PM2.5 and NOx for use in transportation conformity 

determinations to assure that any increases in emissions from this sector do not jeopardize

continued attainment of the annual PM2.5 standard during the ten-year maintenance period. 

Delaware’s Maintenance Plan has been prepared in accordance with the requirements specified 

in EPA’s guidance document, and additional guidance received from EPA staff.

Based on this presentation, New Castle County, Delaware meets the requirements for 

redesignation under the CAA (Section 107(d)(3)) and EPA guidance for fine particles. 

Consistent with the authority granted to EPA, the State of Delaware requests that New Castle 

County, Delaware be redesignated to attainment for the 1997 annual fine particles standard 

simultaneously with EPA approval of this Delaware State redesignation request and annual PM2.5

Maintenance Plan for the New Castle County portion of the Philadelphia NAA.

 

23 Based on MARAMA work, and consultation with PA and NJ, emissions for all of the Philadelphia NAA will 

decrease significantly by 2017 and 2025.