March 12, 2008

Mr. Donald S. Welsh (3APOO) E C F, ! ‘I E D

Regional Administrator

US Environmental Protection Agency

Region III

1650 Arch Street .

Philadelphia, PA, 19103-2029 I1W,iJI iiitt& (3t1)

Dear Mr. Welch:

On June 13, 2007, the State of Delaware submitted two State Implementation Plan (SIP)

revisions entitled (1) “Delaware State Implementation Plan for Attainment ofthe 8-Hour Ozone

National Ambient Air Quality Standard, Reasonable Further Progress and Attainment

Demonstration,” dated June 2007 on its cover page, and (2) “2002 Base Year State

Implementation Plan Emission Inventory for VOC, NOx, and CO for the State of Delaware,”

dated June 1, 2007 on its cover page, to EPA requesting its approval as revisions to Delaware’s

SIP pursuant to section 110 ofthe Clean Air Act.’ The June 13, 2007 submittal consisted of SIP

revisions addressing four elements required by Sections 172(c) and 182 ofthe Clean Air Act as

implemented by Subpart X of 40 CFR part 51 for moderate and above 8-hour ozone

nonattainment areas. These elements are (1) the 2002 base year emissions inventory, (2) the 15

percent reasonable further progress plan (RFP plan) for 2008, (3) the attainment demonstration,

and (4) the contingency measures for 2008 and 2009.

The purpose ofthis letter is to identify the RFP plan and related elements, including the

2002 base year emissions inventory, ofthe June 2007 SIP revisions to make it possible for EPA

to take action to determine the adequacy ofthe mobile budgets in the RFP plan.

The 2002 base year inventory element ofthe June 13, 2007 submittal, required under

section 1 82(a)( 1) as implemented by 40 CFR § 51.915, provides a comprehensive, accurate,

current inventory of actual emissions from all source sectors, including source sectors of

stationary point sources, stationary non-point sources (formerly called area sources), on-road

l The first SIP document is hereafter referred to as “the June 2007 SIP plan”, arid the second SIP document is

referred to as “the 2002 base year inventory.”

Vela4ia4e 4 9ood ltua’e deftecd4 ot
revision (i.e., not as an inclusive part ofthe June 2007 RFP and Attainment Demonstration SIP

plan).

The RFP plan element ofthe June 13, 2007 submittal provides for emission reductions by

2008 of at least 15 percent from baseline emissions required by Section 182(b)(1) asimplemented by 40 CFR § 51.91 0(a)(1 )(i)(A). The element consists ofthe following portions of

the June 2007 SIP plan:

(1) Sections 1 and 2 ofthe June 2007 submittal serve for general introductory purposes.

Section 1 includes a brief discussion ofthe background for the RFP element and relevant

RFP requirements under the CAAA and EPA’s guidance rules. Section 2 presents ananalysis of Delaware’s ambient air quality regarding the previous 1-hour ozone standardand the current 8-hour ozone standard. The section concludes that a decreasing trend ofambient ozone concentrations in Delaware has been observed in the past decade or so,

and the trend is likely to continue in the future years.

(2) Section 3 provides a summary ofthe 2002 base year emission inventory. Since CO

emission reduction is not required in the RFP and attainment demonstration, the summary

includes the 2002 VOC and NOx emissions only. The VOC and NOx emissions in this

chapter are used as base emission levels for calculating RFP emission reductions in the

chapters to follow.

(3) Section 4 provides detailed calculations for assessing 2008 RFP emission reductions

required under CAA. Specifically, Subsection 4.1 provides details of how Delawareadjusts the 2002 base year VOC and NOx emission levels. In Delaware, the adjustments

involve only non-creditable reductions, which are solely due to the implementation of the

pre-1990 Federal Motor Vehicle Control Program (FMVCP) and Reid Vapor Pressure

(RVP) rule, and exist in the on-road mobile source sector only. As discussed in thissubsection, Delaware conducts the adjustments strictly following EPA’s guidance

documents and the timely instructions provided by EPA’s Region 3 Office. Appendix 4-

1 to this section provides the MOBILE6.2 input and output files, as well as the detailed

calculations for obtaining the 2008’s adjustments to the 2002 base year mobile emissions.

Subsection 4.2 provides calculations for assessing the 15% VOC emission reductions by

2008 for Sussex County (an marginal non-attainment area without an approved 15%

VOC emission reduction plan under the 1-hour ozone standard), and for Kent/New Castle

Counties (an severe non-attainment area with an approved 15% VOC reduction plan

under the I-hour standard). The 2008 VOC emission targets for Sussex County and forKent/New Castle Counties are also calculated in this subsection.
subsections 5.1, 5.2, 5.3 a

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interpolating method is used upon the 2002 adjusted base year emissions and the 2009

projections for obtaining the 2008 emission projections for those source categories where

there are no new controls between 2008 and 2009. Section 5 discusses only the controls

which are new and/or specific in 2008. Specifically, Subsection 5.1 discusses the VOCemission control on crude oil lightering operation in Sussex County, the facility

shutdowns in Kent and New Castle Counties, and the Consent Agreement for NOx

emission control at Premcor Refinery (a facility in New Castle County); Subsection 5.4discusses the 2008 on-road mobile source VOC and NOx emission projections using

EPA’s MOBILE6.2 model with the 2008 VMTs based on the most-recent-availablevehicle registration data and speed estimates. Appendix 6-3 (to Section 6 ofthis SIP

plan) provides MOBILE6.2 input and output files, as well as the detailed calculations for

obtaining the 2008 mobile emissions.

Subsection 5.5 sunimarizes VOC emission projections in all 4 sources sectors in Sussex

County, and in Kent/New Castle Counties, and concludes that the existing and upcoming

controls in Delaware will lead to VOC emission projections that will meet the RFPemission targets in both Sussex County and in Kent/New Castle Counties.

(5) Section 9 provides the 2008 on-road mobile source emission budgets for transportation

conformity. As explained at the beginning ofthis section, Delaware had developed a

mobile budget SIP revision and submitted to EPA in May 2007 to meet EPA’s

requirements. Section 9 briefly describes how Delaware develops the 2008 mobilebudgets and presents the 2008 VOC and NOx budget numbers. Appendix 9-I to this

section provides a complete copy ofDelaware’s May 2007 Mobile Budgets SIP

submittal.

(6) Section 10 addresses the contingency measures in the 2008 milestone year. Subsection

10.1 briefly discusses the relevant requirements under the CAAA, and guidance

documents from EPA. Subsection 10.2 provides details of how Delaware managed the

contingency issue for 2008. This subsection concludes that Delaware’s NOx emission

reductions in 2008 will be significantly beyond the REF contingency requirements (as

indicated in Subsection 5.4), and therefore no contingency measures are needed to bespecified in 2008.

Other sections and/or subsections in the June 2007 SIP plan not discussed above are

related to the attainment demonstration element and the 2009 contingency measure element of

the June 13, 2007 ozone SIP submittal.
We look forward to continuing the cooperation between Delaware and EPA in the

attainment ofthe ozone NAAQS. Please feel free to contact Ali Mirzakhalili, Administrator of

DNREC’s AQM Section, (302) 739-9402, if you have any question regarding this letter and/or

our June 13, 2007 ozone SIP submittal.

SipcereIy, 7

.

Ii;-.‘-.

John A. 1-lughes

Secretary

cc: Judy Katz

Ali Mirzakhalili

Jim Werner