Proposed

Delaware 

State Implementation Plan (SIP) Revision

Demonstration that Amendments to 

Section 2.0 of 7 DE Admin Code 1142, Control of NOx

Emissions from Industrial Boilers and Process Heaters at 

Petroleum Refineries Do not Interfere with Any Applicable 

Requirement of the Clean Air Act

Delaware Department of Natural Resources and Environmental Control

December 7, 2010
1

1. Introduction

In November 2009, Delaware promulgated Section 2.0 of 7 DE Admin Code 1142, 

Control of NOx Emissions from Industrial Boilers and Process Heaters at Petroleum Refineries. 

In June 2010, Section 2.0 of 1142 was approved by the Environmental Protection Agency (EPA)

into Delaware’s State Implementation Plan (SIP) (75 FR 31711). 

The purpose of Section 2.0 of 7 DE Admin Code 1142 is to reduce nitrogen oxides (NOx) 

emissions from large industrial boilers and process heaters that are located at petroleum 

refineries. This reduction in NOx emissions from the affected units would aid in the attainment 

and maintenance of any national ambient air quality standard (NAAQS), and any other 

applicable requirement that is affected by NOx emissions. NAAQSs and applicable requirements 

that are affected by NOx emissions are:

Ozone NAAQS. NOx emissions impact air quality relative to ozone. This is because 

ozone is formed through a reaction in the atmosphere between NOx and volatile organic 

compounds (VOC) in the presence of heat and sunlight (i.e., NOx and VOC are 

precursors to the formation of ozone). The air quality in Delaware is designated under 

Section 107 of the Clean Air Act (CAA) as not meeting the 1997 health based NAAQS of 

0.08 ppm for ozone. In addition, the EPA issued a revised 8-hour ozone NAAQS of 

0.075 ppm in March 2008, and has proposed to reconsider that revised NAAQS in 

January of 2010. The air quality in Delaware is anticipated to be designated as nonattainment under the new ozone NAAQS. 

Under the 1997 ozone NAAQS the entire state of Delaware is included as part of a 

Philadelphia based non-attainment area (NAA). Delaware submitted to the EPA an 

attainment demonstration SIP in July 2007 which demonstrated that the NAA would 

attain compliance with that NAAQS by 2010. EPA has not yet issued area designations 

for the 2008 revised NAAQS, and has not yet finalized its reconsideration of the 2008 

revised NAAQS. 

Fine Particulate Matter (PM2.5) NAAQS. NOx emissions contribute to the formation of

nitrate particulates in the atmosphere, and nitrate particles are PM2.5 (i.e., they are 

particles with an aerodynamic diameter of 2.5 microns or less). The air quality in New 

Castle County Delaware is designated under Section 107 of the CAA as not meeting the

1997 health based NAAQS for PM2.5. In addition, the EPA issued a revised PM2.5

NAAQS in 2006. 

Under the 1997 NAAQS New Castle County Delaware is included as part of a 

Philadelphia based NAA. Delaware submitted to the EPA an attainment demonstration 

SIP in April 2008 which demonstrated that the NAA would attain compliance with the 

NAAQS by 20101. Relative to the 2006 PM2.5 NAAQS, New Castle County Delaware is 

 

1 Based on 2007-2009 monitoring data, New Castle County has attained the 1997 NAAQS for the annual and daily 

standard. 
2

designated as non-attainment for the daily standard, and is included as part of the 

Philadelphia based NAA. The attainment demonstration SIP is due in December 2012.2 

Visibility. NOx emissions contribute to the formation of PM2.5, and PM2.5 is a visibility 

impairing pollutant under the federal regional haze program. Visibility impairing 

emission from Delaware have been determined to “significantly”3impact one (1) federal 

class 1 area, Brigantine National Wildlife Area, in New Jersey. 

The State of Delaware submitted to the EPA in September 2009 a Visibility SIP that met 

the requirements of Part C to Title I of the CAA. This SIP primarily relied upon SO2

reductions, because sulfate was determined by the Regional Planning Organizations to be 

the main cause of visibility impairment in Class I areas. However, the SIP also partially 

relied on reductions in NOx emissions to demonstrate that Delaware has met its 2018 

visibility related goals.

Nitrogen Dioxide (NO2) NAAQS. NOx emissions, by definition, directly impact 

ambient NO2 concentrations. The air quality in Delaware is designated under Section 107 

of the CAA as meeting the current annual NO2 NAAQS. In February 2010, the EPA 

revised the annual NO2 NAAQS and issued a new hourly NO2 NAAQS. 

EPA has not issued designations of areas under the 2010 revised NAAQS, and State 

recommendations for designation of areas are due to the EPA in January 2011. 

Section 2.0 of 7 DE Admin Code 1142 does not limit emissions of any pollutant other 

than NOx. Section 2.0 covers nine (9) emission units at the Delaware City Refinery, and imposes 

compliance dates between 2007 and 2012, depending on the particular emission unit. 

In 2009 the operations of equipment at the Delaware City Refinery were discontinued, and 

in 2010 the refinery ownership changed from Premcor Refining Group Inc. to Delaware City 

Refining Company, LLC (“DCRC”). Two actions related to this change in ownership impact 

Delaware’s SIP:

On May 28, 2010, the Delaware Department of Natural Resources and Environmental 

Control (the Department) reached an enforcement settlement with Premcor. This 

settlement, among other things, terminated the 2008 FCCU NOx Agreement which 

had required the Premcor fluid catalytic cracking unit CO boiler to meet a 20 parts 

per million (ppm) NOx emission limitation by May 1, 2009. 4

 

2 Based on 2007-2009 monitoring data, New Castle County has already attained the 2006 PM2.5 NAAQS. 

3 As a result of the consultation process, the Middle Atlantic and Northeast Visibility Union (MANE-VU) States

defined contributions to Class I areas as “significant” if a State contributed at least 2 percent of total sulfate observed 

on the 20 percent worst visibility days in 2002. Based on the MANE-VU Contribution Assessment and the 

application of the “≥ 2% SO2 rule,” emissions from Delaware were determined to contribute to visibility degradation 

exclusively to the Brigantine Wilderness Class I area (note that NOx was not the primary pollutant of concern in this 

round of Regional Haze SIPs).

4

2008 Consent Decree with Premcor Refinery at Delaware City, The FCCU NOx Agreement 
3

On May 31, 2010 the Department and DCRC reached an agreement on DCRC’s 

acquisition, restart and operation of the Delaware City Refinery. One element of that 

agreement provides that the Department will propose to revise Section 2.0 of 7 DE 

Admin Code 1142 to provide for a facility-wide NOx emission cap compliance 

alternative. 

In a separate regulatory process, Delaware is proposing to revise Section 2.0 of 7 DE 

Admin Code 1142 to (1) provide for the control of NOx from the Fluid Catalytic Cracking Unit 

CO boiler to the level that was previously required by the 2008 consent agreement, and (2) 

provide for a facility-wide NOx emission cap compliance alternative. The purpose of this SIP 

revision is to demonstrate that these revisions to Section 2.0 of 7 DE Admin Code 1142 will not 

interfere with attainment or maintenance of any NAAQS, or any other applicable requirement of 

the CAA. 

Questions or comments regarding this SIP revision should be addressed to Ronald A. 

Amirikian, Planning Branch Manager, Division of Air Quality, Delaware Department of Natural 

Resources and Environmental Control, at (302) 739-9402 or ronald.amirikian@state.de.us.

2. Impact Analysis 

Section 2.0 of 7 DE Admin Code 1142 sets emission limits only for the pollutant NOx, 

and only impacts the Delaware City Refinery (i.e., the Delaware City Refinery is the only 

petroleum refinery within the State of Delaware). This analysis considers the effect the revisions 

to Section 2.0 of 7 DE Admin Code 1142 have on applicable requirements for which NOx 

emissions are a precursor or pollutant of interest. That is, the pollutants ozone, PM2.5, visibility, 

and NO2. 

2.1. Baseline NOx emissions from the Delaware City Refinery.

Ozone. 2002 is the SIP base year for planning associated with the 1997 0.08 ppm ozone 

NAAQS. Actual 2002 base year NOx emissions from the Delaware City Refinery were 

3,555 TPY. For the 2008 revised NAAQS, which is currently being reconsidered, a SIP 

planning base year has not yet been determined. The most current emission inventory is 

2008, and actual 2008 NOx emissions from the Delaware City Refinery were 2,525 TPY.

PM2.5. 2002 is the SIP base year for planning associated with the 2008 PM2.5 15 ug/m3

annual, and the 65 ug/m3daily NAAQSs. Base year 2002 NOx emissions are identical 

to those identified under ozone above. For the 2008 revised NAAQS, a SIP planning 

base year has not yet been determined. The most current emission inventory is 2008, 

and actual 2008 NOX emissions from the Delaware City Refinery were those identified 

under ozone above.

Visibility. 2002 is the SIP base year for planning associated with Delaware’s 2008 

Visibility SIP. Base year 2002 NOx emissions are those identified under ozone above. 
4

NO2. For the 2010 revised NAAQS, area designation has not yet occurred, and a SIP 

planning base year has not yet been determined. The most current emission inventory is 

2008, and actual 2008 NOx emissions from the Delaware City Refinery were those 

identified under ozone above.

2.2. Projected NOx emissions from the Delaware City Refinery under current (i.e., before 

revision) Section 2.0 of 7 DE Admin Code 1142.

Ozone. Delaware’s 2007 Ozone SIP demonstrates that compliance with the 1997 

0.08ppm ozone NAAQS will be achieved in 2009, based on 2009 projected emission 

levels. 2002 was the SIP base year, and 2002 base year NOx emissions (see 2.1 above) 

were projected to 2009 by applying factors that account for projected growth and 

controls. The projection calculations are explained in detail in the 2007 ozone SIP.

The following five (5) emission units received post-2002/Pre-2009 emission controls that 

were relied upon in the 2007 ozone SIP calculations5:

Boiler 1 (Unit 80-1) – 80% control from 7 DE Admin Code 11426

Boiler 2 (Unit 80-2) – 80% control from 7 DE Admin Code 1142

Crude Unit vacuum Heater (Unit 21-H-2) – 60% control from 1142

Fluid Catalytic Cracking Unit CO Boiler – 86.7% control from 2008 

Consent Decree7

Methanol Plant Heater 41-H-1 – 100% control from 2003 shut down

Resultant 2009 attainment year emissions from the Delaware City Refinery (i.e., those 

after the application of growth, the 41-H-1 shutdown, the control of Units 80-1, 80-2, 21-

H-2, and the Cracker CO boiler) were estimated at 2,855 TPY. 

PM2.5. Delaware’s 2008 PM2.5 SIP demonstrates that compliance with the 1997 15 

ug/m3 annual, and the 65 ug/m3 daily standards will be achieved in 2009, based on 2009 

projected emission levels. 2002 was the SIP base year, and 2002 base year NOx 

emissions (see 2.1 above) were projected to 2009 by applying factors that account for 

projected growth and controls. The projection calculations are those discussed under 

ozone above.

Visibility. Delaware’s 2009 Visibility SIP is based on 2018 projected emission levels. 

 

5 Note that the Crude Unit Atmospheric Heater (Unit 21-H-701) is regulated by 7 DE Admin Code 1142. 1142 

imposes a limit of 0.04 lb/mmbtu, however, this limit was previously imposed in 1996 as a LAER limit pursuant to 

7 DE Admin Code 1125. Unit 21-H-701 will remain subject to the 0.04 lb/mmbtu limit independent of 7 DE Admin 

Code 1142 because it was a NSR derived limitation

6

2.0 of 7 DE Admin Code 1142, Control of NOx Emissions From Industrial Boilers and Process Heaters at 

Petroleum Refineries, Effective 2008. Note: this regulation was revised effective 11/11/2009, and the 11/11/2009 

revision was approved into the DE SIP at 75 FR 31711 on June 4, 2010.

7 Consent Decree with Premcor Refinery at Delaware City, The FCCU NOx Agreement.
5

Section 2.0 of 7 DE Admin Code 1142 provides for compliance dates between 2009 and 

2012. In 2012 the requirements of 7 DE Admin Code are fully implemented. As part of 

Delaware’s 2009 Visibility SIP, 2002 NOx emissions from the Delaware City Refinery 

were projected to be 2,761 TPY, and 2,774 TPY, for 2012 and 2018, respectively. 

The 1142 related NOx controls relied upon in the Visibility SIP were:

Boiler 1 (Unit 80-1) – 80% control from 7 DE Admin Code 1142

Boiler 2 (Unit 80-2) – 80% control from 7 DE Admin Code 1142

Crude Unit vacuum Heater (Unit 21-H-2) – 60% control from 1142

Fluid Catalytic Cracking Unit CO Boiler – 86.7% control from 2008 

Consent Decree

Methanol Plant Heater 41-H-1 – 100% control from 2003 shut down

Boilers 80-3 and 80-4 – 100% control from shutdown on or before May 1, 

2011. 8

NO2. For the 2010 revised NAAQS, area designation has not yet occurred. The 2002 and 

2008 actual NOx emissions, and the 2009, 2012 and 2018 projected NOx emissions 

discussed above are used to evaluate the impact that the revisions to Section 2.0 of 7 DE 

Admin Code 1142 would have on future NO2 NAAQS planning. 

2.3. Revision to Section 2.0 of 7 DE Admin Code 1142.

Delaware is revising Section 2.0 of 7 DE Admin Code 1142 to (1) provide for the control 

of NOx emissions from the Fluid Catalytic Cracking Unit CO Boiler (Unit 23-H-3) that 

was previously required under a 2008 consent decree, and (2) provide for, as an option, 

compliance with a facility-wide NOx cap as an alternative to unit specific NOx emission 

limitations. 

The initial facility-wide cap is being established at the level of Premcor’s actual 2008 

NOx emissions (i.e., 2,525 TPY), and will decline in two step decreases, as follows:

2,525 tons per year, evaluated over each twelve (12) consecutive month 

rolling period, for any twelve (12) month rolling period ending on or before 

January 2014. 

2,225 tons per year, evaluated over each twelve (12) consecutive month 

rolling period, commencing with the twelve (12) month rolling period 

beginning on December 31, 2013 and ending on December 31, 2014. 

1,650 tons per year, evaluated over each twelve (12) consecutive month 

rolling period, commencing with the twelve (12) month rolling period 

beginning on December 31, 2014 and ending on December 31, 2015.

 

8 Note that in the current Delaware SIP Boilers 3 and 4 are not required to shutdown, and the allowable emission 

rate for Boilers 1, 3 and 4 were finalized at 0.015 lb/mmbtu limit, 24-hour rolling average basis. See also footnote 4.
6

Under the revised Section 2.0 of 7 DE Admin Code 1142, either all of the unit specific 

NOx emission limitations apply or the facility-wide cap apply at all times (i.e., there is no 

gap in compliance). 

2.4. Impact of Revised 7 DE Admin Code 1142 on ozone, PM2.5, visibility and NO2, (i.e., the 

requirements for which NOx emissions are a precursor or pollutant of interest). 

The addition of emission limits to Section 2.0 of 7 DE Admin Code 1142 applicable to 

Unit 23-H-3 do not in any way change the emission limits for this unit. That is, the 

emissions limit for Unit 23-H-3 do not change, but only the vehicle by which these 

emission limits will be enforced is changing (i.e., it will be enforced through Section 2.0 

of 7 DE Admin Code 1142 instead of a consent agreement). In other words, no change is 

being made that could upset the status quo.

With the revision to 2.0 of 7 DE Admin Code 1142 described in 2.3 above, the Delaware 

City Refinery may comply by either (1) complying with all of the unit specific emission 

limitations specified in 7 DE Admin Code 1142, or (2) complying with the applicable 

facility-wide NOx emission cap.

Complying with all of the unit specific emission limitations specified in 7 DE Admin 

Code 1142. 

This is the current compliance mechanism in Section 2.0 of 7 DE Admin Code 1142. 

Therefore, since overall no change is being made to the unit specific emission rates

this compliance option would not impact any NAAQS or applicable requirement (i.e., 

no change is being made that could upset the status quo).

Complying with the applicable facility-wide NOX emission cap. Under this

compliance option, emission units will not be subjected to the unit specific emission 

limitations of Section 2.0 of 7 DE Admin Code 1142, and instead the entire facility 

will be subject to a facility-wide NOX cap. 

Compliance with the 7 DE Admin Code 1142 facility-wide caps is required monthly, 

on a 12-month rolling basis. For standards where compliance is demonstrated on an 

annual or longer basis, an annual cap is generally consistent with a NAAQS with an 

annual averaging period. 

The NO2 and PM2.5 NAAQS both have a standard which is averaged on an “annual” 

basis. For the NO2 annual NAAQS, this is the arithmetic average of all of the 

reported 1-hour values (40 CFR Part 50, Appendix S). For both of the PM2.5 annual 

NAAQSs (1997 and 2006), the annual standard design value, which is based upon 3 

years of valid annual means, is compared to the NAAQS (40 CFR Part 50 Appendix 

N). The design value is an average of three annual means over three consecutive 

years. An annual mean is the average of the average values for each of the four 

quarters in a calendar year; the average value for each quarter is the average of the 

daily values for that quarter. 
7

As long as the cap set by 7 DE Admin Code 1142 is lower than a baseline condition 

(i.e., 7 DE Admin Code 1142 before amendment), a conclusion that the revised 

Section 2.0 of 7 DE Admin Code 1142 will cause no worsening of air quality is 

supported. 

The table below summarizes the Delaware City Refinery NOX emission data 

presented in 2.1 and 2.2 above.

Year NOX (TPY)

2002 (actual) 3,555

2008 (actual) 2,525

2009 (projected) 2,855

2012 (projected) 2,761

2018 (projected) 2,774

As discussed in 2.3 above, the facility-wide NOX cap will start at 2,525 TPY, and 

decline to 1,650 TPY in 2015. This declining cap option provides for emissions that 

are lower than the actual and projected emission levels under the current unit specific 

control option. This indicates that the facility-wide NOX emission cap compliance 

option will not negatively impact the 1997 and 2006 annual PM2.5 NAAQSs, the 2010

annual NO2 NAAQS, and visibility related goals

Complying with the applicable facility-wide NOX emission cap – Additional 

Analysis. For standards where compliance is demonstrated on a more frequent basis, 

additional analysis is needed. This is because a 12-month rolling total could provide 

for higher emissions on a seasonal or a daily basis. 

The 1997 and 2008 ozone NAAQSs is directly related to the highest concentration 

averaged over an 8-hour period in any one (calendar) day. The 2010 daily NO2

NAAQS is determined by comparing the 1-hour primary standard design value, 

which is the average of three annual 98th percentile values, to the NAAQS (40 CFR 

Part 50, Appendix S). Likewise, compliance with the 1997 and 2006 24-hour PM2.5

NAAQSs is determined by comparing the 24-hour standard design value, which is an 

average the annual 98th percentile values for each of three years (40 CFR Part 50 

Appendix N). 

In addition to the comparison between the actual and projected emissions and the 

facility-wide cap discussed above, seasonal variations were evaluated. The 

Department analyzed monthly crude oil throughputs from the crude oil tank farm, 

which is an indicator of the capacity factor of the refinery. Historical throughput is 

useful data to analyze because such data supports a conclusion that utilization will not 

drastically vary by month in the future. Four (4) years, 2005 through 2008, were 

evaluated (see table below). 
8

Crude Tank Farm Throughput (%)

2005 2006 2007 2008

January 8.4 7.6 8.7 10.2

February 7.6 8.0 6.7 8.3

March 6.9 8.1 8.2 9.8

April 8.2 8.5 8.2 8.3

May 9.4 8.7 8.7 7.8

June 9.1 8.4 8.6 9.4

July 9.4 8.6 9.0 10.0

August 8.8 8.8 8.8 10.0

September 9.5 8.5 7.8 10.0

October 8.4 8.5 8.7 10.1

November 6.7 8.2 8.2 3.9*

December 7.7 8.3 8.4 2.2*

*Note: November and December of 2008 are determined 

to be not representative of normal operations. The 

refinery was running as significantly reduced rates during 

these months because the crude unit had its turnaround in 

November 2008 and the Coker was down. Because of this 

2008 was not evaluated further.

Based on 2005, 2006 and 2007 crude tank farm throughput, the Department 

concludes there is a slight bias high during the ozone season months. However, given 

the monthly deviation is slight (36-month average percent is 8.3, and the standard 

deviation from the average is 0.7), and given that the facility-wide NOx caps are less 

than the recent actual and projected emissions, the Department concludes that refinery 

operations in the future will be essentially uniform throughout the year, and the 12-

month rolling caps are consistent with NAAQS and other applicable requirements. 

In addition to crude oil throughputs from the crude oil tank farm, the Department has 

also analyzed the variability of daily emissions from the Delaware City Refinery. 

This was done by analyzing actual historical NOX emissions for the refinery units that 

are covered by 7 DE Admin Code 1139, “Nitrogen Oxides (NOX) Budget Trading 

Program.” The NOX emissions from units subject to 7 DE Admin Code 1139 are 

monitored by continuous emission monitoring systems (CEMS). Historical NOx 

emissions data for these units were obtained from EPA’s Clean Air Market’s Division 

(CAMD) at http://camddataandmaps.epa.gov/gdm for calendar years 2005 through 

2007. 

Analysis of Daily Average NOX Emissions: The daily average NOX emissions for all 

units reporting to CAMD, in TPD, for CY2005, 2006, and 2007, by month, are as 

follows: 
9

Daily Average NOX Emissions (TPD)

2005 2006 2007

January 8.6 5.7 7.3

February 8.7 8.4 7.4

March 8.1 8.3 6.8

April 8.2 8.0 6.7

May 8.3 8.3 6.2

June 8.8 7.9 6.8

July 7.7 6.2 7.1

August 7.0 5.7 7.6

September 7.5 6.3 6.7

October 6.0 8.2 7.2

November 5.0 7.9 7.2

December 6.2 6.1 7.5

Stdev 1.2 1.1 0.4

Average 7.5 7.2 7.0

The daily average NOX emissions for each month between January 2005 and 

December 2007 is within one (1) standard deviation of the annual average daily NOX

emissions for each month for all three (3) years, except for June 2005 (which is 1.03 

standard deviations from the average). This indicates there is little variation in daily 

NOX emissions from month to month, and that operations under a 12-month rolling 

total facility-wide NOX cap will not result in high daily NOX emissions during times 

of bad air quality, and would not negatively impact applicable requirements. 

Analysis of Highest Single Day NOX Emissions: The highest single day’s NOX

emissions for all units reporting to CAMD, in TPD, for calendar years 2005, 2006, 

and 2007, by month, are as follows: 

Highest Single Day NOX Emissions 

(TPD)

2005 2006 2007

January 11.0 7.5 8.8

February 9.8 9.4 9.1

March 10.5 9.5 8.2

April 9.4 11.4 13.0

May 10.8 9.4 7.2

June 11.1 9.1 7.9

July 9.6 7.8 8.6
10

August 8.5 7.1 8.9

September 9.4 8.1 8.1

October 11.3 10.2 8.9

November 6.5 10.0 9.0

December 8.3 7.2 8.6

Stdev 1.4 1.3 1.4

Average 9.7 8.9 8.8

Delaware’s air quality is generally worst in the hot summer months of June, July and 

August. The highest single day NOX emission from the Delaware City Refinery were 

generally outside of this period. In all three (3) of the years analyzed the highest 

daily NOX emissions occurred during months were air quality is generally good in 

Delaware (i.e., October for 2005, and April for 2006 and 2007). In addition, only in 

three (3) months out of the thirty-six (36) months (i.e., October 2005, April 2006, and 

April 2007) analyzed did the highest single day NOX emission exceed the highest 

single day annual average plus one (1) standard deviation. This indicates that

operations under a 12-month rolling total facility-wide NOX cap will not provide for 

high emissions on bad air quality days, and will not negatively impact applicable 

requirements.

Analysis of the Number of Days that NOX Emissions exceed Annual Average plus 1 

standard deviation: The table below shows the number of days were daily NOX

emission were greater than the annual average emissions plus one (1) standard 

deviation.

Number of Days NOX Emissions 

Were Greater Than Annual 

Average Plus 1 Standard Deviation

2005 2006 2007

January 4 4 9

February 4 5 5

March 2 8 2

April 4 2 3

May 4 5 4

June 6 5 4

July 5 2 5

August 4 7 3

September 6 8 4

October 5 3 4

November 5 5 4

December 3 6 4
11

Out of these three (3) years, the maximum number of days that the daily NOx 

emissions exceed the mean/average plus one (1) standard deviation was only 9 

(January 2007). On only seven (7) out of these thirty-six (36) months did the daily 

NOx emissions exceed one (1) standard deviation more than 5 times. And, the 

number of times the daily NOX emissions exceeded one (1) standard deviation is 

constant from month to month.

The above analysis indicates that relative to the 1997 ozone NAAQS, the planning 

assumptions used in the 2007 attainment demonstration SIP would not be undermined by 

the revisions to Section 2.0 of 7 DE Admin Code 1142. This is because refinery 

operations do not vary significantly from month to month, and actual emissions levels do 

not vary significantly over an ozone season or do not vary significantly on a daily basis 

within the months of the ozone season. Relative to the 2008 ozone NAAQS, planning is 

now underway but base year and attainment years have not yet been set. Preservation of 

the status quo air quality will prevent interference with Delawares’ obligations to develop 

timely attainment demonstrations, and no interference with the ozone NAAQS (i.e., no 

change is being made that would upset the status quo).

Relative to the daily standard of the 2006 PM2.5 NAAQS (which sets a lower threshold 

than the 1997 daily NAAQS and would address the daily standard under the 1997 

NAAQS for which New Castle County is in attainment), the above analysis also indicates 

that the planning assumptions used in the 2008 attainment demonstration SIP would not 

be undermined by the revisions to Section 2.0 of 7 DE Admin Code 1142 (i.e., a 12-

month rolling cap is consistent with attainment because refinery utilization and emissions 

do not vary significantly from month to month or from day to day).

Relative to the NO2 NAAQS, area designations have not yet occurred. Because refinery 

operations do not vary significantly from month to month, and actual emissions levels do 

not vary significantly over the year, preservation of the status quo air quality will prevent 

interference with Delawares’ obligations to develop timely attainment demonstrations, 

and no interference with the NO2 NAAQS (i.e., no change is being made that would upset 

the status quo).

3. Conclusion

Delaware concludes that the revisions to Section 2.0 of 7 DE Admin Code 1142 to 1) 

include the NOx control requirement for the Fluid Catalytic Cracking Unit CO boiler that were 

previously provided for in a 2008 consent agreement and 2) provide for a facility-wide NOx cap 

compliance alternative will not interfere with attainment or maintenance of any NAAQS or any 

other applicable requirement of the CAA