Approval and Promulgation of Implementation Plans and Designation of Areas for Air Quality Planning Purposes; State of North Carolina

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 52 and 81

[NC-061-1-7010; FRL-5226-3]

Approval and Promulgation of Implementation Plans and Designation

of Areas for Air Quality Planning Purposes; State of North Carolina

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: EPA is approving a maintenance plan and a request to

redesignate the Charlotte-Gastonia area from nonattainment to

attainment for ozone (O3) submitted on November 12, 1993, by the

State of North Carolina through the North Carolina Department of

Environment, Health, and Natural Resources. Subsequently on December

16, 1994, January 6, 1995, and May 23, 1995, the State submitted

supplementary information which included refined modeling and revisions

to the maintenance plan. The Charlotte-Gastonia O3 nonattainment

area includes Mecklenburg and Gaston Counties. EPA is also approving

the State of North Carolina's 1990 baseline emissions inventory because

it meets EPA's requirements regarding the approval of baseline emission

inventories.

EFFECTIVE DATE: July 5, 1995.

ADDRESSES: Copies of the documents relative to this action are

available for public inspection during normal business hours at the

following locations. The interested persons wanting to examine these

documents should make an appointment with the appropriate office at

least 24 hours before the visiting day.

Air and Radiation Docket and Information Center (Air Docket 6102), U.S.

Environmental Protection Agency, 401 M Street, SW, Washington, DC

20460.

Environmental Protection Agency, Region 4 Air Programs Branch, 345

Courtland Street, NE, Atlanta, Georgia 30365.

State of North Carolina, Air Quality Section, Division of Environmental

Management, North Carolina Department of Environment, Health, and

Natural Resources, Raleigh, North Carolina 27626.

Environmental Management Division, Mecklenburg County Department of

Environmental Protection, 700 N. Tryon Street, Charlotte, North

Carolina 28202-2236.

FOR FURTHER INFORMATION CONTACT: Kay Prince, Regulatory Planning and

Development Section, Air Programs Branch, Air, Pesticides & Toxics

Management Division, Region 4 Environmental Protection Agency, 345

Courtland Street, NE, Atlanta, Georgia 30365. The telephone number is

404/347-3555 extension 4221. Reference file NC-061-1-6815.

SUPPLEMENTARY INFORMATION: On November 15, 1990, the Clean Air Act

Amendments of 1990 were enacted. (Pub. L. 101-549, 104 Stat. 2399,

codified at 42 U.S.C. 7401-7671q). Under section 107(d)(1)(C), EPA

designated Mecklenburg County of the Charlotte-Gastonia area as

nonattainment by operation of law with respect to O3 because the

area was designated nonattainment immediately before November 15, 1990.

The nonattainment area was expanded to include Gaston County per

section 107(d)(1)(A)(i) (See 56 FR 56694 (Nov. 6, 1991) and 57 FR 56762

(Nov. 30, 1992), codified at 40 CFR 81.318.) The area was classified as

moderate.

The moderate nonattainment area had ambient monitoring data that

showed no violations of the O3 NAAQS, during the period from 1990

through 1993. Therefore, on November 12, 1993, the State of North

Carolina submitted an O3 maintenance plan and requested

redesignation of the area to attainment with respect to the O3

NAAQS. The O3 NAAQS continues to be maintained in the Charlotte-

Gastonia area. On January 24, 1994, Region 4 determined that the

information received from the State constituted a complete

redesignation request under the general completeness criteria of 40 CFR

51, appendix V, sections 2.1 and 2.2. Subsequently, on December 16,

1994, and January 6, 1995, the State submitted additional information

that refined the modeling and clarified the future measures needed to

ensure maintenance of the O3 NAAQS. The State requested the

January 6, 1995, information be parallel processed by EPA. The State

held a public hearing on April 19, 1995, and made a final submittal to

EPA on May 23, 1995.

The North Carolina redesignation request for the Charlotte-Gastonia

moderate O3 nonattainment area meets the five requirements of

section 107(d)(3)(E) for redesignation to attainment. The following is

a brief description of how the State of North Carolina has fulfilled

each of these requirements. Because the maintenance plan is a critical

element of the redesignation request, EPA will discuss its evaluation

of the maintenance plan under its analysis of the redesignation

request.

1. The Area Must Have Attained the O3 NAAQS

The State of North Carolina's request is based on an analysis of

quality assured ambient air quality monitoring data, which is relevant

to the maintenance plan and to the redesignation request. Most recent

ambient air quality monitoring data for calendar year 1990 through

calendar year 1994 demonstrates attainment of the standard. The State

of North Carolina has committed to continue monitoring the moderate

nonattainment area in accordance with 40 CFR 58. Therefore, the State

has met this requirement. For detailed information refer to the

proposed document published April 17, 1995 (60 FR 19197).

[[Page 34860]]

2. The Area Has Met All Applicable Requirements Under Section 110

and Part D of the CAA

EPA reviewed the North Carolina SIP and ensures that it contains

all measures due under the amended CAA prior to or at the time the

State of North Carolina submitted its redesignation request. For

detailed information regarding applicable requirements other than

section 182(f), refer to the proposed document.

A. Section 182(a)(1)--Emissions Inventory

North Carolina has met this requirement. This document gives final

approval of the 1990 base line emissions inventory. For detailed

information regarding how this requirement was met, refer to the

proposal document.

B. Section 182(a)(2), 182(b)(2)--Reasonably Available Control

Technology (RACT)

As stated in the proposal document, North Carolina had met all RACT

requirements except those in 182(b)(2), RACT Catch-ups. On January 7,

1994, the State submitted revisions to the SIP that addressed the RACT

Catch-ups. The document approving those revisions was published on

January 26, 1995 (see 60 FR 5138), and became effective on March 27,

1995. Therefore this requirement has been met. For detailed information

regarding this requirement, refer to the proposal document.

C. Section 182(a)(3)--Emissions Statements

In the proposal document, EPA stated that the North Carolina

Emissions Statement regulation must be approved prior to or at the time

of redesignation. On December 17, 1993, North Carolina submitted a

revision to the SIP that met the requirements for an emission statement

regulation. The document approving this revision was published on May

5, 1995 (see 60 FR 22284). No adverse comments were received,

therefore, the effective date of the federal approval is July 5, 1995.

Therefore this requirement has been met. For detailed information

regarding this requirement, refer to the proposal document.

D. Section 182(b)(1)--15% Progress Plans

With the approval of this redesignation request, the requirement to

submit a 15% plan is obviated because the redesignation request

predated the requirement for a 15% plan. Additionally, on May 10, 1995,

EPA, in a memorandum from John S. Seitz, Director, Office of Air

Quality Planning and Standards, issued a new policy regarding planning

requirements of the CAA. Areas that have quality assured air monitoring

data showing attainment with the ozone standard for the most recent

three years are deemed to have attained the standard and such are not

subject to certain requirements of subpart 2 of Part D of title I of

the CAA. Specifically, a moderate area such as Charlotte-Gastonia would

no longer be required to submit a 15% plan or an attainment

demonstration. EPA has published a document making such finding with

respect to the Charlotte-Gastonia area. See the proposal document for

more detailed information.

E. Section 182(b)(3)--Stage II

On January 24, 1994, EPA promulgated the onboard vapor recovery

rule (OBVR), and, section 202(a)(b) of the CAA provides that once the

rule is promulgated, moderate areas are no longer required to implement

Stage II. Thus, the Stage II vapor recovery requirement of section

182(b)(3) is no longer an applicable requirement. See the proposal

document for more detailed information.

F. Section 182(b)(4)--Motor Vehicle Inspection and Maintenance (I/M)

In the proposal document, EPA stated that the North Carolina I/M

regulation must be approved prior to or at the time of redesignation.

On July 19, 1993, North Carolina submitted a revision to the SIP that

met the requirements for an I/M regulation. The document approving this

revision was published on June 2, 1995 (see 60 FR 28720), and the

revision is federally approved. For detailed information regarding this

requirement, refer to the proposal document.

G. Section 182(b)(5)--New Source Review (NSR)

North Carolina has a fully-approved NSR program for moderate

O3 nonattainment areas. For detailed information regarding this

requirement, refer to the proposal document.

H. Section 182(f)--Oxides of Nitrogen (NOX) Requirements

This redesignation request predated the November 15, 1993,

requirement for the submittal of NOX RACT rules. Therefore,

NOX RACT is not an applicable requirement for purposes of this

redesignation request. However, the State has submitted revisions that

would require NOX RACT should the area violate the O3 NAAQS.

This submittal pre-adopts NOX RACT rules as a contingency measure.

Since contingency measures for maintenance are not required to be pre-

adopted, approval of this submittal is not a requirement for

redesignation. Action on that submittal will be taken in another

document since it is not an applicable requirement for purposes of this

redesignation request. For more detailed information regarding this

requirement, refer to the proposal document.

3. The Area Has a Fully Approved SIP Under Section 110(k) of the

CAA

Based on the approval of provisions under the pre-amended CAA and

EPA's prior approval of SIP revisions under the amended CAA, EPA has

determined that the Charlotte-Gastonia area has a fully approved

O3 SIP under section 110(k).

4. The Air Quality Improvement Must Be Permanent and Enforceable

Several control measures have come into place since the Charlotte-

Gastonia nonattainment area violated the O3 NAAQS. Of these

control measures, the reduction of fuel volatility from 10.6 psi in

1987 to less than 9.0 psi in 1990, and finally to less than 7.8 psi

beginning with the summer of 1992, as measured by the Reid Vapor

Pressure (RVP), and fleet turnover due to the Federal Motor Vehicle

Control Program (FMVCP) produced the most significant decreases in VOC

emissions. The reduction in VOC emissions due to the mobile source

regulations from 1987 to 1990 is 26.01 tons per day (29.63%). The VOC

emissions in the base year are not artificially low due to a depressed

economy.

5. The Area Must Have a Fully Approved Maintenance Plan Pursuant to

Section 175A of the CAA

Section 175A of the CAA sets forth the elements of a maintenance

plan for areas seeking redesignation from nonattainment to attainment.

The plan must demonstrate continued attainment of the applicable NAAQS

for at least ten years after the Administrator approves a redesignation

to attainment. Eight years after the redesignation, the state must

submit a revised maintenance plan which demonstrates attainment for the

ten years following the initial ten-year period. To provide for the

possibility of future NAAQS violations, the maintenance plan must

contain contingency measures, with a schedule for implementation,

adequate to assure prompt correction of any air quality problems.

EPA is approving the State of North Carolina's maintenance plan for

the Charlotte-Gastonia nonattainment area

[[Page 34861]]

because EPA finds that the State's submittal meets the requirements of

section 175A.

A. Emissions Inventory

a. Base Year Inventory

On November 13, 1992, the State of North Carolina submitted

comprehensive inventories of VOC, NOX, and carbon monoxide (CO)

emissions from the Charlotte-Gastonia nonattainment area. The inventory

included biogenic, area, stationary, and mobile sources for 1990.

The State of North Carolina submittal contains the detailed

inventory data and summaries by county and source category. Finally,

this inventory was prepared in accordance with EPA guidance. This

action approves the final base year inventory for the Charlotte-

Gastonia area. A summary of the base year inventory is included in the

table below.

1990 Charlotte/Gastonia Typical Summer Day Emissions Tons per Day (TPD)

------------------------------------------------------------------------

Category NOX VOC CO

------------------------------------------------------------------------

Point........................................ 31.25 33.99 35.27

Area......................................... 4.92 67.59 25.00

Non-road..................................... 15.52 19.38 138.45

Biogenic..................................... 2.78 54.41 0

Mobile....................................... 61.64 50.81 371.26

--------------------------

Total...................................... 116.11 226.18 569.98

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b. Emission Budget for Conformity

EPA's transportation conformity regulation requires that states

adopt an emissions budget for conformity for ozone precursors in

maintenance areas. Therefore, the State of North Carolina has adopted

the following emissions budget:

Conformity Emissions Budget

------------------------------------------------------------------------

1999 NOX 1999 VOC 2005 NOX 2005 VOC

Source cat. and county (TPD) (TPD) (TPD) (TPD)

------------------------------------------------------------------------

Mobile:

Mecklenburg............. 33.5 25.5 33.0 25.9

Gaston.................. 9.3 6.3 8.7 5.7

Point:

Mecklenburg............. 2.6 23.0 2.8 24.3

Gaston.................. 79.5 7.3 79.7 7.5

Area:

Mecklenburg............. 3.7 23.0 3.9 33.3

Gaston.................. 1.3 16.7 1.4 16.5

Non-road:

Mecklenburg............. 18.6 20.2 17.8 22.5

Gaston.................. 4.8 5.6 4.1 5.8

------------------------------------------------------------------------

EPA will be taking separate rulemaking action on conformity

emission budgets.

B. Demonstration of Maintenance--Urban Airshed Modeling

a. Control Strategy

The plan must demonstrate maintenance for at least 10 years. The

North Carolina plan demonstrates maintenance out to the year 2005

through the use of the Urban Airshed Model (UAM). On December 16, 1994

and January 6, 1995, the State submitted a revision to the original

maintenance plan submitted to EPA on November 12, 1993, requesting that

EPA parallel process the revisions. These submittals which included

revisions to the modeling pursuant to EPA comment and additional

corrections to the modeling were presented at the public hearing held

in Charlotte on April 19, 1995. The modeling analysis included base and

future case modeling completed according to guidelines presented in the

EPA document ``Guideline for Regulatory Application of the Urban

Airshed Model.'' The future case modeling includes the interim year

1999 and the 10 year maintenance year of 2005. This modeling analysis

did not assume any benefit from the NSR program.

Modeling for all three episodes predicted a small number of grid

cells (X controls would be more effective

in the maintenance of the standard in the Charlotte/Gastonia area, and,

hence, the State originally selected a strategy that consisted

primarily of additional controls of NOX emissions. The selected

control strategy included the following measures:

Reformulated Gasoline to meet the Federal Phase I and

Phase II standards to begin in 1999 in Mecklenburg, Gaston, Union,

Cabarrus, Lincoln, Rowan, and Iredell Counties;

Clean Fuel Fleet Program, including the schedule for

implementation as specified in the CAA for areas classified serious and

above, in the same seven counties previously listed;

Burning bans in the seven counties for the months of June,

July, and August;

Control of NOX for the Transcontinental Natural Gas

Pumping Station in Iredell County for the months of June, July, and

August; and

Additional 10 percent control beyond the control being

applied to meet title IV NOX requirements on Duke Power's Allen

and Riverbend facilities in Gaston County for the months of June, July,

and August.

The State also took comment at the public hearing on the

feasibility of substituting an enhanced I/M program for the

reformulated gasoline measure. The modeling results indicate that such

substitution would show maintenance of the standard. After

consideration of the comments at the public hearing, the North Carolina

Environmental Management Commission adopted the maintenance plan

without additional controls on May 11, 1995.

2. Request for Comments

As requested by the State, EPA is parallel processing the request

and therefore published a document on April 17, 1995, proposing

approval of the maintenance plan and redesignation request and

soliciting comment on the following control scenarios:

[[Page 34862]]

a. Adoption and implementation in 1999 of the five measures as

detailed above;

b. Adoption and implementation in 1999 of the five measures as

detailed above with enhanced I/M substituted for the reformulated

gasoline program;

c. Adoption and implementation in 1999 of the aforementioned

controls on the Transcontinental Natural Gas Pumping Station in Iredell

County and the additional 10 percent control beyond the title IV

requirements on Duke Power's Allen and Riverbend facilities in Gaston

County; or

d. Approval of the request as demonstrating maintenance with no

additional VOC or NOX controls.

EPA received a number of comments on the proposal and the control

scenarios. Those comments and the response thereto are summarized

below.

Comment #1--Rather than controlling emissions, the plan allows an

increase in NOX emissions of 25 tons per day by 1999 in the

nonattainment area and additional increases throughout the modeling

domain.

Response--Section 175A of the CAA requires that a plan showing

maintenance of the applicable NAAQS for 10 years after redesignation be

incorporated as revision to the SIP. In a September 4, 1992, memorandum

from John Calcagni, Director, Air Quality Management Division, EPA

issued guidance on the requirements for redesignation of areas from

nonattainment to attainment. That guidance contains two primary methods

a state may use to demonstrate maintenance of the O3 NAAQS for an

area. The first method is an emissions inventory demonstration which

includes emission projections showing no increases in emissions of

O3 precursors, i.e., NOX and VOC, in the designated

nonattainment area throughout the 10 year maintenance period. This

method would not allow the projected increase in emissions of NOX

in the nonattainment counties. The second method is a modeling

demonstration showing that the projected levels of emissions of O3

precursors would not cause a violation of the NAAQS. The guidance

further stipulates that the level of modeling required must be at least

that required by the CAA for an attainment demonstration for the area.

Since the Charlotte-Gastonia area is a moderate intra-state area, the

level of modeling required would have been EKMA or its equivalent.

However, the State of North Carolina chose to use the UAM model which

is required for inter-state moderate areas as well as serious and above

areas.

For the reasons explained in the proposal and in the responses to

comments on the modeling provided below, EPA believes that the modeling

demonstration, which evaluated a strategy with a combination of

decreases in VOC emissions and increases in NOX emissions,

submitted by the State of North Carolina adequately demonstrated

maintenance of the NAAQS notwithstanding the projected increase in

NOX emissions. Therefore, EPA believes that the increases in

NOX emissions are permissible.

Comment #2--Concern was expressed regarding the emission increases

projected for Duke Power sources located in the area. It was suggested

that for equity, Duke Power should be required or provided incentives

to install additional emission controls.

Response--The Duke Power plants in question are subject to EPA's

acid rain provisions and reductions in NOX emissions will be

obtained from this program. Neither the CAA nor the EPA require a

specific set of measures to ensure maintenance of the O3 NAAQS,

but rather the state determines for each area what additional

reductions, if any, are necessary. The EPA then determines the adequacy

of the plan. EPA has determined, as explained elsewhere, in this

document and the proposal, that the existing control system is adequate

to ensure maintenance of the NAAQS for ten years.

Comment #3--North Carolina has consistently stated that additional

controls are necessary to maintain the standard and that controls on

sources of NOX emissions are the most effective.

Response--The State's assertion that additional NOX controls

would be necessary to maintain the NAAQS after 1999 was based on the

UAM modeling and the view that every grid cell must be below the

standard in order to demonstrate maintenance. However, EPA has

determined, as discussed in the proposal and elsewhere in this

document, that the State's modeling demonstration adequately

demonstrates maintenance of the NAAQS without additional control

measures.

Comment #4--Monitored daily maximum ozone concentrations over the

last five years indicate that the nonattainment area has been on the

verge of violating the O3 NAAQS. Furthermore, the modeling

predicts future exceedances of the NAAQS for all three episodes.

Response--Although two monitors in the ozone nonattainment area and

one monitor in an adjacent county recorded two exceedances of the

O3 NAAQS in 1993, there have been no violations of the NAAQS in

the last five years. Furthermore, there were no exceedances recorded at

any monitor in the area in 1992 or 1994. An area is allowed one

exceedance of the NAAQS per year with a three year average used to

determine attainment/nonattainment status. Therefore, since the

expected exceedance rate for the area is 0.67 which is less than 1.1

and since all monitors are currently monitoring attainment of the

NAAQS, EPA believes that the monitoring data is sufficient to support

redesignation of the area to attainment. EPA's Response to the comments

regarding the modeling is contained in EPA's Response to Comment #5.

Comment #5--One Commenter provided detailed Comments individually

on each of the six items listed in the proposal as support for EPA's

determination that the modeling demonstration is sufficiently

conservative for EPA to conclude that the NAAQS can be maintained

without additional emission controls. In the proposal, EPA explained

that while its modeling guidance generally requires that modeling

results show attainment of the standard in all grid cells, it does

allow alternative methods for demonstrating attainment on a case-by-

case basis. EPA went on to explain its belief that North Carolina's

modeling for the Charlotte-Gastonia area was sufficiently conservative

to provide an adequate demonstration of maintenance without the

adoption of additional controls notwithstanding the model's prediction

of slight exceedances of the standard in a few grid cells. That belief

was based on the combination of the following six factors:

(1) North Carolina has five years of air quality data showing

attainment of the standard.

(2) The maintenance plan contains pre-adopted measures and a

violation would trigger reduction in emissions by the following O3

season.

(3) The O3 standard is a statistically based NAAQS that allows

one exceedance per year.

(4) North Carolina has done extensive modeling to gain an

understanding of the creation of O3 in the Charlotte area and has

generally made conservative assumptions in selecting modeling inputs.

(5) The uncertainties in the biogenic emission inventory and other

modeling inputs are well within the range of the 2-3 ppb needed to

reach the .124 ppm in all grid cells.

(6) The modeling did not account for lower VOC, NOX and

O3 boundary conditions expected when SIP attainment and title IV

(acid rain program) control programs have been

[[Page 34863]]

implemented in many areas throughout the United States.

This commenter took issue with each of the six factors that EPA

referenced in the proposal.

Response--Before responding to the comments on each of the six

factors individually, EPA notes that, as indicated in the proposal, it

was the combination of factors--not necessarily any particular factor

standing alone--that supports EPA's determination that the modeling

provides an adequate demonstration that the ozone NAAQS will be

maintained in the absence of the adoption of additional control

measures. Furthermore, as explained below, the Comments made with

respect to each of the factors individually fail to undermine the

validity of EPA's conclusion that the modeling provides an adequate

demonstration of maintenance. Although the commenter made relevant

points, EPA believes that when considered together, on balance the

factors support the conclusion that North Carolina has adequately

demonstrated that the Charlotte-Gastonia area will maintain the

standard.

(1) North Carolina has five years of air quality data showing

attainment of the standard.

With three years of air quality showing attainment an area can

request redesignation. North Carolina's request is strengthened by the

fact that it has five years of air quality data showing no violations

of the O3 NAAQS.

Based upon a trend analysis performed by EPA, meteorologically

adjusted O3 trends in Charlotte (and surrounding areas) have shown

a modest but consistent improvement of approximately 1 percent per year

between 1983 and 1993. However, the most recent five years analyzed

(1988-1993) have shown an accelerated rate of improvement of

approximately 2 to 3 percent per year (10 percent over the five year

period) suggesting that recent ozone air quality is improving when

meteorological conditions are eliminated.

Moreover, EPA has conducted an analysis of the O3 potential in

the major urban areas, including Charlotte, using available

meteorological data collected over the past 41 years. The study

(currently undergoing review for publication in Atmospheric

Environment), indicates that meteorological conditions favoring high

O3 ranked the summer of 1993 as the 2nd most severe O3 year

in the past 41 years. The two years, 1988 and 1987 were ranked 7th and

4th, respectively. The meteorology for all three years was very

conducive to producing high O3 concentrations. Since North

Carolina did not have a violation in 1993 under meteorological

conditions of comparable severity to the 1988 and 1987 modeling

analyses, this supports the redesignation demonstration.

Although NOX emissions are projected to increase over the

maintenance period, i.e. from the 1990 base line inventory, the State

of North Carolina's experience in other similar areas (Raleigh/Durham

and Greensboro/Winston-Salem) suggests that total NOX emissions in

1999 will be less than 1993. Specifically, the projected emissions from

the three area power plants in 1999 that are the area's primary

NOX sources are less than the actual emissions from those plants

in 1993. Since the area was able to maintain the standard despite the

higher NOX emissions and adverse meteorological conditions in

1993, it would be expected that the projected decrease in power plant

emissions would support the ability for the area to continue to

maintain the O3 NAAQS.

(2) The maintenance plan contains pre-adopted measures and a

violation would trigger reduction in emissions by the following ozone

season. While it is true that the presence of pre-adopted measures in

the maintenance plan triggered by a violation does not make the

modeling analysis conservative, it does add strength to the package as

a whole and will allow the State to implement new controls to quickly

address any future nonattainment problem. The State has done

preliminary modeling analysis on both the pre-adopted and the other

contingency measures listed in the plan which will assist the State in

timely implementation of the most effective measures.

Additionally, the contingency plan contains a secondary trigger

which is an exceedance of the ozone standard that would indicate a

violation could be imminent. This trigger will be activated within 30

days of the State finding the exceedance. Once the secondary trigger is

activated, the State Air Quality Section will commence analysis,

including updated modeling as necessary, to determine what control

measures will be required to keep the area in attainment, with the

regulatory adoption process for any necessary measures beginning by May

1 of the following year. As the contingency measures based on the

secondary trigger should help the area stay in attainment, those

measures should also help the area maintain the standard and do provide

an additional level of assurance that the area will maintain the

standard.

(3) The O3 standard is a statistically based NAAQS that allows

one exceedance per year.

Developing an attainment test using gridded concentrations for a

few selected days to match a NAAQS determination which uses sparsely

located monitors for a complete hourly O3 season is not simple.

Recognizing the severity of O3 forming potential for selected

episodes, as well as the NAAQS allowing one exceedance at each monitor

location over a three year period, led EPA to consider how stringent

the model test of requiring every grid cell modeled across the domain

to be below 124 ppb for all hours might be. Again, based on the

severity of the years modeled, EPA believes the modeling demonstration

indicates that a few grid cells would exceed 124 ppb by a slight amount

(less than 1% with a maximum value of 129 ppb) is within a margin of

safety that the NAAQS will be maintained provided the contingency

measures in the plan are identified and implemented, if the need is

indicated by monitored data. As indicated previously, the State's plan

contains a secondary trigger for contingency measures based on an

exceedance of the O3 NAAQS that would indicate a violation is

imminent.

(4) North Carolina has done extensive modeling to gain an

understanding of the creation of O3 in the Charlotte area and has

generally made conservative assumptions in selecting modeling inputs.

EPA recognizes and allows for uncertainty in model estimates as

part of the model performance evaluation conducted prior to use in

strategy development. EPA guidance includes recommended ranges for

statistical performance measures. For the North Carolina application,

although model estimates were sometimes below the observed highest

concentrations (base case), overall the performance results suggest

that UAM is unbiased and is therefore expected to produce unbiased

estimates of future air quality assuming unbiased (non-conservative)

estimates of future emissions and boundary conditions are used.

In fact, North Carolina was conservative in its choice of model,

years to simulate, boundary conditions and emissions growth factors.

Although, North Carolina was not required to do so, it chose to use UAM

so as to better understand and quantify the effect of ozone precursors

in the area and thus identify the most cost effective strategy for

maintaining the NAAQS. EPA believes North Carolina did select years

that are conducive to high levels of O3 (also see discussion

above) and chose

[[Page 34864]]

episodes for which some of the highest O3 levels were observed in

the area. North Carolina used boundary concentrations along the North

Carolina domain that were only reduced by 5 percent (O3, NOX,

and VOC) so that the maximum level of ozone was 120 ppb for the July

1988 northerly transport episode. It is quite likely that the combined

effect of VOC/NOX controls throughout the eastern U.S. will result

in O3 boundary levels that are below those used in this modeling

exercise. Finally, North Carolina used the 1990 BEA growth factors to

project emissions. These factors were derived before the CAA mandated

controls were implemented and do not take into consideration changes in

business behavior that has occurred as companies have applied

expenditures towards control measures rather than expansion. Also, the

6 year window, 1988-93, used to estimate VMT growth includes very high

growth years and the area is not expected to continue to grow at that

rate. If the State had elected to use lower boundary conditions and

lower growth rates, as allowed by EPA guidelines, it is likely that the

modeling would have predicted ozone levels of 124 ppb or below in all

grid cells.

(5) The uncertainties in the biogenic emissions inventory and other

modeling inputs are well within the range of the 2-5 ppb needed to

reach 124 ppb in all grid cells.

(The sentence above, as included in the proposal document,

contained a typographical error, as it read ``* * * the range of the 2-

3 ppb * * *.'')

As discussed in the response to item (4) above, North Carolina made

very conservative assumptions on model inputs for the NC application

which are within the 2-5 ppb reductions needed to reach 124 ppb. Based

on EPA guidance, North Carolina used the most current and only

regulatory version of the biogenic model available to states at the

time of its modeling analyses. The new version of the biogenic model,

BEIS2, is just now being released for use by states. The impact of the

new model on O3 predictions is still being evaluated. The State of

North Carolina has a commitment to perform modeling analyses in the

future and will use the most current methodologies for all modeling

inputs including BEIS as well as the most current model.

(6) The modeling did not account for lower VOC, NOX and

O3 boundary conditions expected when SIP attainment control

programs have been implemented in many areas through the United States.

Contrary to the assertions of the commenter, boundary conditions

are relevant to modeling episodes for Charlotte. North Carolina modeled

two transport episodes and one stagnation episode. As indicated above,

conservative assumptions on boundary conditions were made for the July

1988 transport episode. The boundary conditions for the other two

episodes, including the stagnation episode, were not reduced. As states

and the Environmental Council of States (ECOS) embark on the Phase II

modeling efforts, North Carolina is within the regional domain being

evaluated. If regional or more local controls appear warranted based on

new analysis, North Carolina will be notified and EPA is confident that

the State will work with EPA (using better information as it becomes

available) to make any adjustment needed to maintain the NAAQS in the

Charlotte area.

Comment #6--The maintenance plan was developed without regard for

the potential effects on the Southern Appalachian Mountains despite

North Carolina's commitment to the Southern Appalachian Mountain

Initiative (SAMI).

Response--The Charlotte-Gastonia modeling analysis was not

specifically designed to evaluate the effects of the plan on the

Southern Appalachian Mountains. Only the O3 inputs in the

Charlotte-Gastonia airshed were required for analysis of the

redesignation of the Charlotte-Gastonia area. The meteorological

episodes modeled for the redesignation request, while significant for

O3 formation in the Charlotte-Gastonia area, do not include a

situation where emissions from the Charlotte-Gastonia area are

transported into the mountain region, which is currently in attainment

and is not adjacent to the Charlotte-Gastonia area. Additionally,

approval of this maintenance plan and redesignation request does not

preclude additional controls being required on the sources in the

Charlotte-Gastonia area as a result of future analysis indicating that

such controls are necessary to protect air quality in the mountain

region. In the event such controls are found to be necessary, EPA has

the authority under section 110(b)(2) to require the adoption of

control measures if the State fails to do so.

Comment #7--There were several comments regarding the proposal by

the State to require Phase II reformulated gasoline (RFG) in a seven

county area beginning in 1999. The commenters noted that since the CAA

requires Phase II RFG in some areas beginning in 2000, that the fuel

may not be available in 1999. Furthermore, several commenters indicated

their belief that an enhanced I/M program would be of greater benefit

at a lower cost in controlling ozone.

Response--As the maintenance plan approved by EPA in this final

action does not include either Phase II RFG or enhanced I/M as a

measure for maintenance of the NAAQS, issues regarding the use of Phase

II RFG or enhanced I/M as maintenance measures are no longer pertinent.

Comment #8--It was commented that the contingency plan should not

include a list of specific options in the maintenance plan and that

contingency measures should not be pre-adopted.

Response--While the commenter is correct that contingency measures

do not have to be pre-adopted, a state may chose whether or not to pre-

adopt any or all of the listed contingency measures. However, EPA

policy does require that the maintenance plan include a list of

possible contingency measures and a schedule for implementing those

measures that are determined to be necessary to ensure continued

maintenance of the NAAQS. EPA's policy is based on section 175A, which

requires that maintenance plans ``contain such contingency provisions

as the Administrator deems necessary to assure that the state will

promptly correct any violation of the standard which occurs after''

redesignation. In any event, the State did not include additional pre-

adopted measures in the final submittal.

Comment #9--The secondary trigger should be eliminated because it

is vague and would raise questions about federal enforceability.

Additionally, one commenter believes interpretation that an exceedance

of the NAAQS should cause a contingency measure to be adopted is too

stringent.

Response--While EPA policy and section 175A require only that a

maintenance plan contain contingency measures triggered by a violation

of a NAAQS, EPA has encouraged states to select triggers based on

events short of a violation in order to prevent violations from

occurring so that the area continues to maintain the NAAQS or to bring

the area back into attainment more quickly should a violation occur

after the trigger event has occurred. For example, the September 4,

1992, memorandum from John Calcagni suggests that states use indicators

such as monitoring, modeling and inventory levels to identify when

early action may prevent a violation.

The secondary trigger in the Charlotte-Gastonia maintenance plan is

used as an alert for the State that action may be needed to ensure

continued maintenance of the NAAQS. The resulting analysis may or may

not

[[Page 34865]]

indicate additional controls are needed. This mechanism is perfectly

consistent with the purpose of a maintenance plan which is to ensure

continued maintenance of the NAAQS. EPA believes that the use of the

secondary trigger will help North Carolina not only to bring the area

back into attainment quickly but to also prevent violations from

occurring.

EPA does not believe the use of an exceedance of the NAAQS as an

indicator which may lead to additional controls causes an enforcement

problem. Under 40 CFR 51.110, states are required to develop control

strategies for the attainment and maintenance of NAAQS. These

strategies must provide for both the attainment of the standards in

nonattainment areas and the maintenance of those standards in

attainment areas. Since NOX and VOC are defined as precursors to

O3, a criteria pollutant for which there is a NAAQS, emission

reductions of NOX and/or VOC are federally enforceable in

attainment areas provided they are part of the federally-approved SIP.

As the CAA requires SIPs for areas redesignated to attainment to

include measures necessary to maintain the NAAQS, emission reductions

required for maintenance of the standard in the future would be

federally enforceable.

Comment #10--If contingency measures are triggered in the near-term

(i.e., before 2003), additional modeling should not be required unless

there has been a significant change in the model inputs and

assumptions.

Response--North Carolina's contingency plan states that additional

analysis will be done if necessary. Therefore, such analysis is not

required, but is within the State's discretion to do if there have been

significant changes in model inputs and assumptions or control

technology to warrant a new analysis. EPA believes the contingency plan

is approvable as written as it provides adequate assurance that

violations will be corrected promptly in accordance with section 175A.

Comment #11--The contingency options from which the State could

choose should continue to include RFG or enhanced I/M, clean fuel fleet

provisions, open burning restrictions, summer NOX controls from

Transcontinental Gas Pipe Line Corporation and 10% beyond title IV from

Duke Power's Riverbend and Allen plants during the summer. In addition,

NOX and possibly VOC RACT should be available as contingency

measures.

Response--The final submittal from the State includes in their list

of possible contingency measures additional NOX and VOC RACT or

greater controls on sources, particularly Duke Power and

Transcontinental Gas Pipe Line Corporation, Stage II vapor control,

RFG, enhancements to the I/M program, clean fuel fleets and any other

measures that may be appropriate and feasible. The State also indicated

it intends to develop an economic incentive program that would provide

incentives to sources that purchase clean alternative vehicles.

Although the State could not adopt RFG rules without receiving a

section 211(c)(1) waiver of preemption from EPA, EPA believes that

North Carolina has identified an adequate and appropriate list of

contingency measures in light of the numerous measures it has listed.

Comment #12--The time schedule provisions of section 181(b) of the

CAA are equally applicable to stationary and mobile sources. If

contingency measures are needed in the future, the time schedules of

the CAA should not be preferentially offered to mobile sources unless

stationary sources have the same option.

Response--Stationary source controls can often be implemented on a

faster time frame than mobile source controls. It is generally clear

what sources are subject to such rules and what is required for a

source to comply. Mobile source measures are more difficult to develop

and implement as there is a greater need for public education on mobile

related programs. They also often take more time to implement. One of

the primary considerations for choosing a contingency measure to

implement is the time needed to develop, adopt and implement the

measures necessary to prevent or correct a NAAQS violation. If the

analysis shows that stationary sources play an important role in such a

strategy, then implementation should be achieved as soon as possible.

Comment #13--The contingency plan should provide the State with the

flexibility to implement all, or any subset, of the above contingency

measures as a first round of controls, if needed. However, once one of

the contingency measures has been chosen and activated from the above

list, no additional controls would be imposed on that category of

sources until the other first round contingency control options have

been activated. If a second round is required, than modeling should be

used to develop a new balanced and cost-effective strategy.

Response--The primary purpose of the contingency plan is to bring

an area back into attainment should the area violate the NAAQS after

redesignation. The choice of which measures to implement lies with the

state so long as the measures from which the state is choosing are

effective. The North Carolina contingency plan provides the State with

adequate flexibility to enact the measures which will be most effective

in returning the area to attainment.

C. Verification of Continued Attainment

Continued attainment of the O3 NAAQS in the nonattainment area

depends, in part, on the State of North Carolina's efforts toward

tracking indicators of continued attainment during the maintenance

period. The primary trigger of the contingency plan will be a violation

of the ambient air quality standard for ozone. The trigger date will be

the date that the State certifies to EPA that the data is quality

assured, which will occur no later than 30 days after the recorded

violation. The secondary trigger of the contingency plan will be an

exceedance of the ozone standard that would indicate a violation could

be imminent. This trigger will be activated within 30 days of the State

finding the exceedance.

Once either the primary or the secondary trigger is activated, the

State Air Quality Section will commence analysis, including updated

modeling as necessary, to determine what control measures will be

required to bring the area back into attainment. By May 1 of the year

following the ozone season in which the primary trigger has been

activated, the State will complete the analysis and adopt stationary

control measures indicated by the analysis, using the emergency rule

process as necessary. The time frame for adopting measures other than

for stationary sources will be based on the time frames in section

181(b) of the CAA. Where only the secondary trigger has been activated,

the State will complete the analysis and begin the regulatory adoption

process for any measures that are needed by May 1 of the following

year.

D. Contingency Plan

The level of VOC and NOX emissions in the nonattainment area

will largely determine its ability to stay in compliance with the

O3 NAAQS in the future. Despite the State's best efforts to

demonstrate continued compliance with the NAAQS, the ambient air

pollutant concentrations may exceed or violate the NAAQS. Therefore,

the State of North Carolina has provided contingency measures with a

schedule for implementation in the event of a future O3 air

quality problem. The actual measures will be determined from the

analysis process described in

[[Page 34866]]

the Verification of Continued Attainment portion of this document. The

measures analyzed will include RACT or greater level control for

NOX and VOC sources, particularly Duke Power and Transcontinental

Gas Pipe Line Corporation, Stage II vapor control for gasoline

dispensing facilities, RFG, enhancements to the I/M program, clean fuel

fleet program, transportation control measures, and any other

appropriate and feasible measures. EPA finds that the contingency plan

provided in the State of North Carolina's submittal meets the

requirements of section 175A(d) of the CAA.

E. Subsequent Maintenance Plan Revisions

In accordance with section 175A(b) of the CAA, the State of North

Carolina has agreed to submit a revised maintenance SIP eight years

after the nonattainment area is redesignated to attainment. Such

revised SIP will provide for maintenance for an additional ten years.

Additionally, the State has indicated that should analysis of the

current pre-adopted RACT contingency measures demonstrate that they

will not be the most effective in bringing the area back into

attainment, they may revise these pre-adopted measures in the future.

Furthermore, based on updated analysis, the State has indicated they

may periodically revise the contingency plan. All such revisions will

be subject to full public participation in the regulatory adoption

process.

Final Action

EPA approves the State of North Carolina's request to redesignate

to attainment the Charlotte-Gastonia O3 nonattainment area and

maintenance plan. As discussed above, the emission statement, RACT

catch-ups, and I/M requirements have been approved. EPA also approves

the 1990 baseyear inventory for the Charlotte-Gastonia nonattainment

area.

EPA finds that there is good cause for this redesignation to become

effective immediately upon publication because a delayed effective date

is unnecessary due to the nature of a redesignation to attainment,

which exempts the area from certain Clean Air Act requirements that

would otherwise apply to it. The immediate effective date for this

redesignation is authorized under both 5 U.S.C. section 553(d)(1),

which provides that rulemaking actions may become effective less than

30 days after publication if the rule ``grants or recognizes an

exemption or relieves a restriction'' and section (d)(3), which allows

an effective date less than 30 days after publication ``as otherwise

provided by the agency for good cause found and published with the

rule.''

Under section 307(b)(1) of the Act, 42 U.S.C. 7607(b)(1), petitions

for judicial review of this action must be filed in the United States

Court of Appeals for the appropriate circuit by September 5, 1995.

Filing a petition for reconsideration by the Administrator of this

final rule does not affect the finality of this rule for purposes of

judicial review nor does it extend the time within which a petition for

judicial review may be filed, and shall not postpone the effectiveness

of such rule or action. This action may not be challenged later in

proceedings to enforce its requirements. (See section 307(b)(2) of the

Act, 42 U.S.C. 7607(b)(2).)

The OMB has exempted these actions from review under Executive

Order 12866.

Nothing in this action shall be construed as permitting or allowing

or establishing a precedent for any future request for a revision to

any state implementation plan. Each request for revision to the state

implementation plan shall be considered separately in light of specific

technical, economic, and environmental factors and in relation to

relevant statutory and regulatory requirements.

Under the Regulatory Flexibility Act, 5 U.S.C. 600 et seq., EPA

must prepare a regulatory flexibility analysis assessing the impact of

any proposed or final rule on small entities. 5 U.S.C. 603 and 604.

Alternatively, EPA may certify that the rule will not have a

significant impact on a substantial number of small entities. Small

entities include small businesses, small not-for-profit enterprises,

and government entities with jurisdiction over populations of less than

50,000.

Redesignation of an area to attainment under section 107(d)(3)(E)

of the CAA does not impose any new requirements on small entities.

Redesignation is an action that affects the status of a geographical

area and does not impose any regulatory requirements on sources. The

Administrator certifies that the approval of the redesignation request

will not affect a substantial number of small entities.

Unfunded Mandates

Under Sections 202, 203, and 205 of the Unfunded Mandates Reform

Act of 1995 (``Unfunded Mandates Act''), signed into law on March 22,

1995, EPA must undertake various actions in association with proposed

or final rules that include a Federal mandate that may result in

estimated costs of $100 million or more to the private sector, or to

State, local, or tribal governments in the aggregate.

Through submission of this state implementation plan or plan

revision, the State and any affected local or tribal governments have

elected to adopt the program provided for under section 175(A) and

section 187(a)(1) of the Clean Air Act. These rules may bind State,

local and tribal governments to perform certain actions and also

require the private sector to perform certain duties. To the extent

that the rules being approved by this action will impose no new

requirements; such sources are already subject to these regulations

under State law. Accordingly, no additional costs to State, local, or

tribal governments, or to the private sector, result from this action.

EPA has also determined that this final action does not include a

mandate that may result in estimated costs of $100 million or more to

State, local, or tribal governments in the aggregate or to the private

sector.

List of Subjects

40 CFR Part 52

Environmental protection, Air pollution control, Carbon monoxide,

Hydrocarbons, Incorporation by reference, Intergovernmental relations,

Nitrogen dioxide, Ozone, Reporting and recordkeeping requirements.

40 CFR Part 81

Air pollution control, National parks, Wilderness areas.

Dated: June 19, 1995.

Patrick M. Tobin,

Acting Regional Administrator.

Chapter I, title 40, Code of Federal Regulations, is amended as

follows:

PART 52--[AMENDED]

1. The authority citation for part 52 continues to read as follows:

Authority: 42 U.S.C. 7401-7671q.

Subpart II--North Carolina

2. Section 52.1770 is amended by adding paragraph (c)(83) to read

as follows:

Sec. 52.1770 Identification of plan.

* * * * *

(c) * * *

(83) The maintenance plan and redesignation request for the

Charlotte-Gastonia area which include Mecklenburg and Gaston Counties

submitted by the State of North Carolina on November 12, 1993.

(i) Incorporation by reference.

(A) The following subsections of Section 3.0, entitled Maintenance

Plan,

[[Page 34867]]

in the Supplement To The Redesignation Demonstration and Maintenance

Plan for the Charlotte/Gaston Ozone Nonattainment Area adopted by the

North Carolina Environmental Management Commission on May 11, 1995: 3.1

Concept of North Carolina's Maintenance Plan; 3.2 Foundation Control

Program; Table 3.2 of Subsection 3.3; and 3.4 Contingency Plan.

(ii) Other material. None.

PART 81--[AMENDED]

1. The authority citation for part 81 continues to read as follows:

Authority: 42.U.S.C. 7401-7671q.

2. In Sec. 81.334, the ozone table is amended by removing the

Charlotte-Gastonia area and its entries in the first alphabetical list

and by adding in alphabetical order entries for ``Gaston County'' and

``Mecklenburg County'' to the second listing of counties to read as

follows:

Sec. 81.334 North Carolina.

* * * * *

North Carolina--Ozone

----------------------------------------------------------------------------------------------------------------

Designation Classification

-------------------------------------------------------------------------------

Date\1\ Type Date\1\ Type

----------------------------------------------------------------------------------------------------------------

Rest of State................... ........................... Unclassifiable/Attainment.. ......... .........

* * * * * *

*

Gaston County................... July 5, 1995...............

* * * * * *

*

Mecklenburg County.............. July 5, 1995...............

* * * * * *

*

----------------------------------------------------------------------------------------------------------------

\1\This date is November 15, 1990, unless otherwise noted.

* * * * *

[FR Doc. 95-16358 Filed 7-3-95; 8:45 am]

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