/. 

c· . UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

Office of Air Quality Planning and Standards 

Research Triangle Park, North Carolina 27711 

NOV 161994 

MEMORANDUM 

SUBJECT: 

FROM: 

' TO: 

Limited Maintenance Plan Option for Nonclassifiable 

O~,.e1 ~o~at~reas· 

S~~aver, Director 

Air Quality Strategies & Standards.Division (MD-15) 

Director, Air, P.esticides and Toxics 

Management Division, Regions I and IV 

Director, Air and Waste Management Division, 

Region II 

Director, Air, Radiation and Toxics Division, 

Region III 

Director, Air and Radiation Division, 

Region V 

Director, Air, Pesticides and Toxics Division, 

Region VI 

Director,- Air and Toxics Division,· 

Regions VII, VIII, IX, and X 

I. Purpose 

This memorandum sets forth new guidance on maintenance plan 

requirements for certain nonclassifiable ozone nonattainment 

areas seeking rede-signation to attainment.· In particular, 

nonclassifiable ozone areas whose design values are at or below 

0.106 ppm (85 percent of exceedance levels of the ozone NAAQS) at 

the time of redesignation may choose to submit a less rigorous 

maintenance plan than was formerly required. This new option is 

being termed a limited maintenance plan. Nonclassifiable ozone 

areas with design values greater than 0.106 ppm will continue to 

be subject to full maintenance plan requirements described in the 

September 4, 1992 memorandum, "Procedures for Processing Requests 

to Redesignate Areas to At"tainment," from John Calcagni, former 

Director of the OAQPS Air Quality Management Division to the 

Regional Air Division Directors. 

There are three types of nonclassifiable ozone. areas: 

submarginal, transitional, and incomplete/no data. A description 

of these areas is included as Attachment A. 

Appendix A
2 

( II. Background 

Section 107(d) (3) (E) of the Act provides that a 

nonattainment area can be redesignated to attainment if the 

following criteria are met: 

,i 

1. The ·EPA has-determfned that the ·NAAQS for the·applicable 

pollutant has been attained. ... 

2. The applicable implementation plan has been fully 

adopted under section 110(k). 

3. The EPA has determined that the improv.ement in air. 

quality is due to permanent and enforceable reductions in 

emissions. 

4. The State- has met all app·licable requirements· for the 

area under section 110 and part D. 

5. The EPA has fully approved a-maintenance plan, including 

a contingency plan, for the area under section 175A. 

Section 175A- of· the Act. provides the -genera·!· framework ·for . maintenance . plans. The maintenance plan must provide for 

maintenc:mce of -th-e···NAAQS for- at-lea-st··lo-years after -- · · ·· ---

redesignation,-1- -includ-ing· any additional control measures as -may --· be ·necessary ·to-.:.ensure- such maintenance. I·n addition, 

maintenance plans are to contain such contingency provisions as . EPA deems necessary to· assure the prompt correction ·of a . · violation of the NAAQS that occurs- after redesignation. The 

.contingency measures must include( at a minimum, a requirement 

that the-State.will implement all control measures contained in 

the nonattainment SIP prior to redesignation. 

Beyond these requirements, however, section 175A does not 

define the content of amaintenance plan. Thus, EPA has the 

authority to exercise reasonable discretion to determine those 

requirements. The EPA has previously issued guidance on meeting 

all five criteria for redesignation including maintenance plans 

(see Attachment B). The EPA now believes that it is justifiable 

and appropriate to apply a d_.ifferent set·of·maintenance plan 

requirements (described herein) to a limited category of ozone 

nonattainment areas--nonclassifiable areas whose monitored air 

quality is equal to or less than 85 percent of exceedance levels 

of the ozone NAAQS. The EPA does not believe that the full 

maintenance plan requirements need be applied to these areas 

because they have achieved air quality levels well below the 

'section 175A also requires that 8 years after 

redesignation, the State must submit an additional plan to 

provide for maintenance for a second follow-on 10-year period. 
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standard without the application of control measures required by 

the Act for classified ozone nonattainment areas. Also, these 

areas do not have either a recent history of monitored violation 

of the ozone NAAQS or a long prior history of monitored air 

quality problems. The EPA believes that the continued 

applicability of prevention of signif~cant deterioration (~SD) 

requirements, any control measures already in the SIP, and 

Federal measures (such as the Federal motor vehicle control 

program) should provide adequate 1assurance of maintenance for 

these areas. 

III. Qualifying for the Limited Maintenance Plan Option . . 

To qualify for the limited maintenance plan option, the 

ozone design value for the a~ea, based on the 3 years of data 

used to demonstrate attainment, must be at or below 0.106 ·ppm 

(85 percent of exceedance· levels· of the-·ozone·NAAQS)-~-··· - · -·- · - Additionally, the design value for the area must continue to be 

at or below o .106 ppm unti-l the time. o.f. f.i-nal--EPA action. on- the - redesignation. The method for calculating design values is 

presented in the June_ 18, 1990.memorandum,. "Ozone and.Carbon 

Monoxide Design Value Calculations," from William G. Laxton, 

former Director of the ·OAQPS Technical Support-~ Division- to 

Regional Air Directors. The memorandum .focuses--primarily on 

determining design values for nonattainment areas in order to 

classify the areas as. marginal, moderate, .serious, severe, or 

extreme. Therefore, ... the document discusses determining the 

design value for an area based on the monitors .which· are ~ · · exceeding the standard. _ In the case of a nonattainment area 

seeking redesignation to attainment, all monitors must be meeting 

the standard. To assess whether a nonclassifiable area meets the 

applicability cutoff for the limited maintenance plan, a separate 

design value must be developed for every monitoring site. The 

highest of these design values is the design value for the whole 

area. If the area design value is at or below 0.106 ppm, the 

State may select the limited maintenance plan option for the 

first 10-year maintenance period. If the design value for the 

area exceeds 0.106 prior to final EPA action on the 

redesignation, the area no longer qualifies for the limited 

maintenance plan and must instead submit a full maintenance plan. 

The EPA will issue guidance in the future on the applicability of 

the limited maintenance plan option to the second follow-on 10-

year maintenance period. 

IV. Limited Maintenance Plan Elements 

Following is a list of core provisions which should be 

included in a limited maintenance plan. Any final EPA 

determination regarding the adequacy of a limited maintenance 

plan will be made following review of the plan submittal in light 

of the particular circumstances facing the area proposed for 

redesignation and based on all relevant available information. 
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a. Attainment Inventory 

The State should develop an attainment emissions inventory 

to identify a level of emissions in the area which is sufficient 

to attain the NAAQS. This inventory should be consistent with 

EPA's most recent guidance2 on emissio~s inventories for _ nonattainment.areas avaiiable at the time and should represent 

emissions during the time period•associated with the monitoring 

data showing attainment. The inventory should be based on actual 

"typical summer day" emissions of voc·and NOx (ozone precursors). 

Emissions of CO are not necessary in the attainment inventory 

because they will not be tracked for maintenance purposes. 

b. Maintenance Demonstration 

The maintenance demonstration.requirement is considered to 

be -satisfied for--nonclassifiable ·areas--if -the ·monitoring data-----------

show the area is meeting·the air quality criteria discussed . above.. There is--no- requirement to- project- emissions over the ··-- ---- . ----- -- maintenance period. The EPA believes if the area begins the 

maintenance period. at. or below .as. percent of .. exceedance levels,.. 

the air quality along with the continued applicability of PSD 

requirements, ·any control measures·already in the SIP 1 and 

Federal measures, should provide adequate-assurance of 

maintenance over the initial 10-year·maintenance period. 

When EPA approves a limited maintenance.plan, EPA is 

concluding that· an. emissions budget :may -.be ·treated as essentially 

not constraining for the length of ·the maintenance period because 

it is unreasonable to expect that .·such -an area will experience so 

much growth in.that period that a violation of the ozone NAAQS 

would result. 

c. Monitoring Network/Verification of Continued Attainment 

To verify the attainment status of the area over the 

maintenance period, the maintenance plan should contain 

provisions for continued operation of an appropriate, EPAapproved air quality monitoring network, in accordance with 40 

CFR part 58. This is particularly· important for areas using a 

limited maintenance plan because there will be no cap on .. emissions. 

2

The EPA's current guidance on the preparation of emissions 

inventories for ozone areas is contained in the following 

documents: "Procedures for the Preparation of Emission 

Inventories for Carbon Monoxide and Precursors of Ozone: Volume 

I" (EPA-450/4-91-016) , "Emission Inventory Requirements for ozone 

State Implementation Plans" (EPA-450/4-91-010), and "Procedures 

for Emission Inventory Preparation: Volume IV, Mobile sources" 

(EPA-450/4-81-026d). 
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d. Contingency Plan 

Section 175A of the Act requires that a maintenance plan 

include contingency provisions, as necessary, to promptly correct 

any violation of the NAAQS that occurs after redesignation of the 

area. These contingency ~easures do ~t have to be fully adopted 

at the time of redesignation. However, the contingency plan is 

considered to be an enforceable part of the SIP and should ensure 

that the contingency measures are~adopted expeditiously once they 

are triggered by a specified event. The contingency plan should 

identify the measures to be promptly adopted and provide a 

schedule and procedure for adoption and implementation of the 

measures. The State should also identify specific indicators_, or 

triggers, which will be used to determine when the contingency 

measures need to be implement~d. While a violation of the NAAQS 

is an acceptable trigger, States may wish to choose a previolation action level as a trigger, such as an exceedance of the 

NAAQS. By taking early action, a state may be able to prevent 

any actual violation of .the NAAQS. and, there-fore, . eliminate any 

need on the part of EPA to redesignate an area back to 

nonattainment. 

V. Conformity Determinations Under Limited Maintenance Plans 

The transportation conformity rule (58 FR 62188; 

November 24, 1993) and the general conformity rule (58 FR 63214; 

November 30, 1993) apply to nonattainment areas and maintenance 

areas operating under maintenance plans. . Under either rule,· one 

means of demonstrating·conformity of Federal actions· is to 

-indicate that expected emissions from planned actions are 

consistent with the emissions budget for the area. As discussed 

above in section IV(b), emissions budgets in limited maintenance 

plan areas may be treated as essentially not constraining for the 

length of the initial maintenance period because it is 

unreasonable to expect that such an area will experience so much 

growth in that period that a violation of the ozone NAAQS would 

result. In other words, EPA would be concluding that emissions 

need not be capped for the maintenance period. Therefore, in 

areas with approved limited maintenance plans, Federal actions 

requiring conformity determinations under the transportation 

conformity rule could be con~idered to satisfy the 11 budget test 11 

required in sections 93.118,.93.119, and 93.120 of the rule. 

Similarly, in these areas, Federal actions subject to the general 

conformity rule could be considered to satisfy the 11 budget test 11 

specified in section 93.158(a) (5) (i) (A) of the rule. 

For further information regarding the limited maintenance 

plan option for nonclassifiable ozone areas, please contact Carla 

Oldham at (919) 541-3347. For information regarding 

transportation conformity requirements, please contact Kathryn 

Sargeant of the Office of Mobile Sources at (313) 668-4441. For 
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( .. ·· information regarding general conformity requirements, please 

contact Doug Grano at (919) 541-3292. 

Attachments 

... 
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ATTACHMENT A 

The EPA used 1987-89 as the primary data years in 

determining designations and classifications for ozone areas set 

forth in the November 6, 1991 final rule on Air Quality 

Designations and Classifications (56 FR 56694). Certain ozone 

nonattainment areas could not be classified as marginal or above 

under Table 1 of section 181(a) (1) of~the Clean Air Act either 

because of· incomplete monitoring data·or because they were 

nonattainment pre~enactment but did not violate the standard 

during 1987-89. These areas are•collectively called 

nonclassifiable areas. Nonclassifiable ozone areas consist of 

transitional, submarginal, and incomplete/no data areas. 

Transitional areas 

An area is considered t~ansitional under section 185A if it 

was designated nonattainment both prior to enactment and at the 

time of enactment, -and did not-violate the primary NAAQS for 

ozone over the 3-year period from 1987-1989. 

Section 185A of the Act required EPA to make a 

determination, by June 30, 1992, whether the designated 

transitional areas had continued to meet the ozone NAAQS through 

December 31, 1991. · All 12 transitional areas were attaining the 

NAAQS through December 31, 1991 and none are known to have 

·violated the standard since. In May·and June of 1992; Regional 

Administrators sent letters to Governors of States with . transitional areas notifying them of EPA's determination. 

submarginal areas 

Compliance with -the ozone NAAQS is determined on the basis 

of expected exceedances which include an adjustment for missing 

data. 1 The submarginal category includes areas that violated the 

ozone NAAQS during 1987-89 but had a design value for the period 

of less than .121 ppm (the lower limit for marginal areas) due to 

the adjustment for missing data when calculating expected 

exceedances. Presently, there are no submarginal areas. 

Incomplete/no data areas 

Certain ozone areas designated nonattainment prior to · enactment and at enactment did not have sufficient air quality 

monitoring data to determine whether they were or were not 

violating the NAAQS. These areas are termed incomplete/no data 

areas. These include areas which do not have monitors. 

Currently, there are 47 incomplete/no data areas. 

1

This adjustment procedure is described in 40 CFR part 50.9, 

appendix H. 
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ATTACHMENT B ·. 

The EPA policies for implementing sections 107 and 175A of 

the Act for redesignations are contained in the following' 

memorandums. 

1. "Procedures for _Processing Re,quests to Redesignate Areas 

to Attainment," John Calcagni, Director, Air Quality Management 

Division, September 4, 1992. 

2. "State Implementation Plan (SIP) Requirements for Areas 

Submitting Requests for Redesignation to Attainment of the Ozone 

and Carbon Monoxide (CO) National Ambient Air Quality Standards 

(NAAQS) on or after N·ovember· ~5, 1992,-" Michael Shapiro, ·:Acting 

Assistant Administrator for Air and Radiation, September 17, 

1993. 

3. "State Implementation Plan (SIP) Actions-Submitted in 

Response to Clean Air Act (CAA) Deadlines," John Calcagni, 

-Director, Air. Quality Management Division, October 28, 1992. 

4. "Contingency Measur.es.for Ozone and.Carbon.Monoxide (CO) 

Redesignations," G.T. Helms, Chief, ozone/Carbon Monoxide 

Programs Branch, June 1, 1992. 

5. "General Preamble· for the Implementation of Title I of 

the Clean Air Act Amendments of 1990 11 (57 FR 13498; April·l6, 

1992) •