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. UNITEDSTATESENVIRONMENTALPROTECTIONAGENCY OfficeofAirQualityPlanningandStandards ResearchTrianglePark,NorthCarolina27711 

# NOV161994

MEMORANDUM SUBJECT:

FROM:

' TO: Limited Maintenance Plan Option for Nonclassifiable**O~,.e**

## 1**~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 WasteManagement 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, andX

I. Purpose This memorandum sets forth new guidance on maintenance plan requirements for certain nonclassifiable ozone nonattainment areas seekingrede-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 RedesignateAreas to At"tainment," from John Calcagni, former Director of the OAQPS Air QualityManagement Division to the Regional Air Division Directors. There are three types of nonclassifiable ozone.areas: submarginal, transitional, and incomplete/no data. Adescription of these areas is included as Attachment 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 aremet: ,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 contingencyplan, for the area under section 175A. Section 175A- of·theAct.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 contingencyprovisions as

.EPA deems necessary to·assure the prompt correction·of a .
·violation of the NAAQS that occurs-after redesignation. The .contingencymeasures 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 includingmaintenance 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.

### (:· 3 standard without the application of controlmeasures 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 ofprevention 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 limitedmaintenance 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 ppmunti-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 DesignValue 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 classifythe areas as.marginal, moderate,.serious, severe, or extreme. Therefore,

...the document discusses determining the designvalue for an area based on themonitors.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 limitedmaintenance 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 Statemay select the limited maintenance plan option for the first 10-yearmaintenance 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 limitedmaintenance 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.4

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 shouldbe consistentwith EPA's most recent guidance2 on**emissio~s** inventories for

_ nonattainment.areas avaiiable at the time and should represent emissions during the time period•associatedwith 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 SIP1 and Federal measures, should provide adequate-assurance of maintenance over the initial 10-year·maintenanceperiod. When EPA approves a limited maintenance.plan, EPA is concluding that·an.emissions budget:may-.be·treatedas essentially not constraining for thelength of ·themaintenance periodbecause 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 limitedmaintenance plan because there will be no cap on



## .. emissions.

2The 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).

### ( 5 d. Contingency Plan Section 175A of theAct requires that a maintenance plan include contingencyprovisions, as necessary, to promptly correct any violation of the NAAQS that occurs afterredesignation 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 contingencymeasures**are~adopted** expeditiously once they are triggered by a specified event. The contingencyplan should identify themeasures 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 statemay 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 LimitedMaintenance Plans The transportation conformity rule (58 FR 62188; November 24, 1993) and the general conformityrule (58 FR 63214; November 30, 1993) apply to nonattainment areas and maintenance areas operatingunder 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 limitedmaintenance 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 otherwords, 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 satisfythe 11budget test11 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 11budget test11 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. For6 (

..·· information regarding general conformity requirements, please contact Doug Grano at (919) 541-3292. Attachments

...

## (- 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 onAir 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** CleanAir 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-yearperiod from 1987-1989. Section 185A of the Act required EPA to make a determination, byJune 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. InMay·and June of 1992; Regional Administrators sent letters to Governors of States with

.transitional areas notifying them of EPA'sdetermination.

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.

1This adjustment procedure is described in 40 CFR part 50.9, appendix H.

# . ' 

## (' ATTACHMENT B 

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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 QualityManagement Division, September 4, 1992. 2. "State Implementation Plan (SIP) Requirements for Areas SubmittingRequests for Redesignation toAttainment of the Ozone and CarbonMonoxide (CO) National Ambient Air Quality Standards (NAAQS) on or after N·ovember·**~5,** 1992,-" Michael Shapiro,·:Acting AssistantAdministrator for Air and Radiation, September 17, 1993.3. "State Implementation Plan (SIP) Actions-Submitted in Response to CleanAirAct (CAA) Deadlines," John Calcagni, -Director, Air. QualityManagement Division, October 28, 1992. 4. "ContingencyMeasur.es.for Ozone and.Carbon.Monoxide (CO) Redesignations," G.T. Helms, Chief, ozone/CarbonMonoxide Programs Branch, June 1, 1992. 5. "General Preamble·for the Implementation of Title I of the CleanAirAct Amendments of 199011 (57 FR 13498; April·l6, 1992)•