Approval and Promulgation of State Implementation Plans: Idaho

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[ID2-1-5552a; FRL-5012-8]

Approval and Promulgation of State Implementation Plans: Idaho

AGENCY: Environmental Protection Agency.

ACTION: Final rule.

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SUMMARY: Environmental Protection Agency (EPA) approves the State

Implementation Plan (SIP) submitted by the State of Idaho for the

purpose of bringing about the attainment of the national ambient air

quality standards (NAAQS) for particulate matter with an aerodynamic

diameter less than or equal to a nominal 10 micrometers (PM-10). The

implementation plan was submitted by the State and satisfied certain

Federal requirements for an acceptable moderate nonattainment area PM-

10 SIP for Pinehurst, Idaho.

DATES: This final rule will be effective on October 24, 1994 unless

adverse or critical comments are received by September 26, 1994. If the

effective date is delayed, timely notice will be published in the

Federal Register.

ADDRESSES: Written comments should be addressed to: Montel Livingston,

Environmental Protection Agency, 1200 Sixth Avenue, AT-082, Seattle,

Washington 98101.

Documents which are incorporated by reference are available for

inspection during normal business hours at the Air and Radiation Docket

and Information Center, Environmental Protection Agency, 401 M Street

SW., Washington, DC 20460. Copies of material submitted to EPA may be

examined during normal business hours at the following locations:

Environmental Protection Agency, 1200 Sixth Avenue, Seattle, WA 98101,

and the State of Idaho Division of Environmental Quality, 1410 N.

Hilton, Boise, ID 83720.

FOR FURTHER INFORMATION CONTACT: Stephen Fry, Environmental Protection

Agency, 1200 Sixth Avenue, AT-082, Seattle, Washington 98101, (206)

553-2575.

SUPPLEMENTARY INFORMATION:

I. Background

The Shoshone County, Pinehurst, Idaho area was designated

nonattainment for PM-10 and classified as moderate under sections

107(d)(4)(B) and 188(a) of the Clean Air Act, upon enactment of the

Clean Air Act Amendments of 1990\1\ (see 56 FR 56694 (November 6, 1991)

and 40 CFR 81.313 (codified air quality designation for the Pinehurst

area)). The air quality planning requirements for moderate PM-10

nonattainment areas are set out in subparts 1 and 4 of title I of the

Act.\2\ EPA has issued a ``General Preamble'' describing EPA's

preliminary views on how EPA intends to review SIP's and SIP revisions

submitted under title I of the Act, including those State submittals

containing moderate PM-10 nonattainment area SIP requirements (see

generally 57 FR 13498 (April 16, 1992) and 57 FR 18070 (April 28,

1992)). Because EPA is describing its interpretations here only in

broad terms, the reader should refer to the General Preamble for a more

detailed discussion of the interpretations of title I advanced in this

proposal and the supporting rationale. In this rulemaking action on the

State of Idaho's moderate PM-10 SIP for the Pinehurst nonattainment

area, EPA is applying its interpretations taking into consideration the

specific factual issues presented. Additional information supporting

EPA's action on this particular area is available for inspection at the

address indicated above.

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\1\The 1990 Amendments to the Clean Air Act made significant

changes to the Act. See Public Law No. 101-549, 104 Stat. 2399.

References herein are to the Clean Air Act, as amended (``the Act''

or ``CAA''). The Clean Air Act is codified, as amended, in the U.S.

Code at 42 U.S.C. 7401, et seq.

\2\Subpart 1 contains provisions applicable to nonattainment

areas generally and subpart 4 contains provisions specifically

applicable to PM-10 nonattainment areas. At times, subpart 1 and

subpart 4 overlap or conflict. EPA has attempted to clarify the

relationship among these provisions in the ``General Preamble'' and,

as appropriate, in today's notice and supporting information.

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Those states containing initial moderate PM-10 nonattainment areas

(those areas designated nonattainment under section 107(d)(4)(B)) were

required to submit, among other things, the following provisions by

November 15, 1991:

1. Provisions to assure that reasonably available control measures

(RACM) (including such reductions in emissions from existing sources in

the area as may be obtained through the adoption, at a minimum, of

reasonably available control technology (RACT)) shall be implemented no

later than December 10, 1993;

2. Either a demonstration (including air quality modeling) that the

plan will provide for attainment as expeditiously as practicable but no

later than December 31, 1994, or a demonstration that attainment by

that date is impracticable;

3. Quantitative milestones which are to be achieved every three

years and which demonstrate reasonable further progress (RFP) toward

attainment by December 31, 1994; and

4. Provisions to assure that the control requirements applicable to

major stationary sources of PM-10 also apply to major stationary

sources of PM-10 precursors except where the Administrator determines

that such sources do not contribute significantly to PM-10 levels which

exceed the NAAQS in the area (see sections 172(c), 188, and 189 of the

Act).

States with initial moderate PM-10 nonattainment areas were

required to submit a permit program for the construction and operation

of new and modified major stationary sources of PM-10 by June 30, 1992

(see section 189(a) of the CAA). This permit program element, also

known as the New Source Review (NSR) program, was submitted by the

State of Idaho on May 17, 1994. EPA notified Idaho in a June 10, 1994

letter to the Administrator of the Idaho Division of Environmental

Quality that the NSR program submittal was complete. EPA is currently

in the process of reviewing the NSR program to determine if the program

meets the requirements of the CAA. EPA intends to take action on

Idaho's NSR program when EPA has completed its review.

In addition, states containing initial moderate PM-10 nonattainment

areas were required to submit contingency measures by November 15,

1993, which become effective without further action by the State or EPA

upon a determination by EPA that the area has failed to achieve RFP or

to attain the PM-10 NAAQS by the applicable statutory deadline (see

section 172(c)(9) and 57 FR 13543-13544). Contingency measures for the

Pinehurst PM-10 nonattainment area have not yet been submitted by IDEQ.

A findings letter, dated January 13, 1994, was mailed to the Governor

of Idaho which informed him that the State had failed to make the

required PM-10 contingency measures submittal for Pinehurst. The State

has until July 13, 1995 to correct this deficiency for Pinehurst, or it

will face Federal highway or offset sanctions (see section 179 of the

CAA and 58 FR 51270 (October 1, 1993)).

EPA intends to take action on the contingency measures for the

Pinehurst PM-10 nonattainment area when this requirement is submitted

or intends to impose sanctions in the event this deficiency is not

corrected.

II. This Action

Section 110(k) of the Act sets out provisions governing EPA's

review of SIP submittal (see 57 FR 13565-13566). In this action, EPA is

granting approval of the plan revision submitted to EPA on April 14,

1992. EPA has determined that the submittal meets the applicable

requirements of the Act, with respect to moderate area PM-10 submittal.

Analysis of State Submission

1. Procedural Background

The Act requires states to observe certain procedural requirements

in developing implementation plans and plan revisions for submission to

EPA. Section 110(a)(2) of the Act provides that each implementation

plan submitted by a State must be adopted after reasonable notice and

public hearing.\3\ Section 110(l) of the Act similarly provides that

each revision to an implementation plan submitted by a State under the

Act must be adopted by such State after reasonable notice and public

hearing.

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\3\Also Section 172(c)(7) of the Act requires that plan

provisions for nonattainment areas meet the applicable provisions of

section 110(a)(2).

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EPA has also determined whether a submittal is complete and

therefore warrants further EPA review and action (see section 110(k)(1)

and 57 FR 13565). EPA's completeness criteria for SIP submittals are

set out at 40 CFR part 51, appendix V. EPA attempts to make

completeness determinations within 60 days of receiving a submission.

However, a submittal is deemed complete by operation of law if a

completeness determination is not made by EPA six months after receipt

of the submission.

The Idaho Division of Environmental Quality (IDEQ) held a public

hearing on the Pinehurst PM-10 plan on January 22, 1992 in Pinehurst

and, after IDEQ reviewed the oral testimony, the plan was adopted by

the IDEQ Administrator on April 7, 1992. The submitted plan was

received by EPA on April 14, 1992 as a revision to the SIP.

The SIP revision was reviewed by EPA to determine completeness

shortly after its submittal, in accordance with the completeness

criteria set out at 40 CFR part 51, appendix V. A letter dated June 8,

1992 was forwarded to the Administrator of IDEQ indicating the

completeness of the submittal and the next steps to be taken in the

review process. In this action EPA is approving the State of Idaho's

PM-10 SIP submittal for the Pinehurst PM-10 nonattainment area.

Since the Pinehurst PM-10 SIP requirements due on November 15, 1991

were not submitted by that date as required by section 189(a)(2)(A) of

the CAA, EPA made a finding, pursuant to section 179 of the Act, that

the State failed to submit the SIP revision and notified the Governor

in a letter dated December 18, 1991 (see 57 FR 19906 (May 8, 1992)).

EPA's June 8, 1992 determination that the State had made a complete

submittal corrected the State's failure to submit the PM-10 SIP

requirements for Pinehurst due on November 15, 1991 and, therefore,

terminated the 18-month sanctions clock for that deficiency under

section 179 of the CAA.

2. Accurate Emissions Inventory

Section 172(c)(3) of the Act requires that nonattainment plan

provisions include a comprehensive, accurate, current inventory of

actual emissions from all sources of relevant pollutants in the

nonattainment area. The emissions inventory should also include a

comprehensive, accurate, and current inventory of allowable emissions

in the area (see section 110(a)(2)(K) of the CAA). Because the

submission of such inventories is necessary to an area's attainment

demonstration (or demonstration that the area cannot practicably

attain), the emissions inventories must be received with the submission

(see 57 FR 13539).

The base year emission inventory (1988) developed for the Pinehurst

nonattainment area identified the major sources of PM-10 concentrations

during 24-hour worst case winter days as residential wood combustion

(59%), fugitive dust (38%) and other sources (3%). Annual emissions for

1988 were residential wood combustion (41%), fugitive dust (38%),

building construction (18%) and other sources (3%).

EPA is approving the emissions inventory because it generally

appears to be accurate and comprehensive, and provides a sufficient

basis for determining the adequacy of the attainment demonstration for

this area consistent with the requirements of sections 172(c)(3) and

110(a)(2)(K) of the Clean Air Act.\4\ For further details see the

Technical Support Document (TSD).

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\4\The EPA issued guidance on PM-10 emissions inventories prior

to the enactment of the Clean Air Act Amendments in the form of the

1987 PM-10 SIP Development Guideline. The guidance provided in this

document appears to be consistent with the amended Act; therefore,

EPA may continue to rely on this guidance (see section 193 of the

CAA).

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3. RACM (Including RACT)

As noted, the initial moderate PM-10 nonattainment areas must

submit provisions to assure that RACM (including RACT) were implemented

no later than December 10, 1993 (see sections 172(c)(1) and

189(a)(1)(C)). The General Preamble contains a detailed discussion of

EPA's interpretation of the RACM (including RACT) requirement (see 57

FR 13539-13545 and 13560-13561).

a. Residential Wood Combustion Program. Attainment of the 24-hour

and annual standards is based on control strategies designed to reduce

wood smoke. Attainment is demonstrated through the establishment of a

voluntary residential wood combustion curtailment program, wood stove

replacement program and home weatherization program. The specific

control measures are supported and enhanced through an aggressive air

pollution public awareness program. More details regarding these

control measures are as follows:

(1) Episodic Wood Burning Curtailment Program. The IDEQ is in

charge of declaring episodic voluntary wood burning curtailments in the

Pinehurst nonattainment area. A voluntary burn ban is declared when 24-

hour PM-10 levels in the nonattainment area, as estimated by

nephelometer, are measured to exceed 100 g/m3. To keep

the public informed regarding particulate air quality levels, a 24-hour

PM-10 prediction is made for the Pinehurst/Silver Valley area after an

IDEQ meteorologist calculates lower atmospheric stability and evaluates

nephelometer, upper air temperature sounding, snow cover, surface

temperature, delta temperature, wind speed, cloud cover, National

Weather Service and occasionally commercial weather service data.

Wood burning advisories are made in conjunction with the air

quality report and are issued weekdays and, as necessary on weekends

and holidays, by 9 a.m., from November 1 through the end of February.

The advisory is recorded on a telephone answering machine for both the

public and media. When a voluntary wood burning curtailment is

declared, the IDEQ directly contacts the media and conducts radio and

television interviews to publicize the existence of a burn ban.

Voluntary curtailment declarations are also carried routinely by the

local radio station and newspaper.

IDEQ requests a 25 percent emission reduction credit for its

voluntary curtailment program in the Pinehurst nonattainment area

during 24-hour worst case periods. The 25 percent credit is greater

than the ten percent generally suggested by EPA for voluntary

curtailment programs. The recommended ten percent credit is viewed by

EPA as a ``starting point in assessing the effectiveness of residential

wood combustion control programs.'' However, final judgement of the

amount of credit to be granted is determined by EPA's regional offices

based on the program features outlined in EPA's Guidance Document for

Residential Wood Combustion Emission Control Measures, September 1989,

(EPA-450/2-89-015). More than ten percent credit may be granted based

on the program's effectiveness.

IDEQ cites residential wood heating surveys that were conducted in

the Ada County/Boise PM-10 nonattainment area, that indicate a 43

percent effectiveness rate for the voluntary curtailment program in

that part of Idaho. The State points out in the Pinehurst SIP that the

Pinehurst City Council adopted a resolution (on November 11, 1991)

supporting the curtailment program and requesting all Pinehurst

citizens, except those who must rely on wood burning as their sole

source of heat, to not burn wood during a curtailment episode.

Therefore, the features of the Pinehurst curtailment program, the

effectiveness data obtained from Ada County/Boise coupled with the

demonstrated local support for the curtailment program by the leaders

of Pinehurst is the basis for IDEQ's 25 percent emission reduction

claim. According to IDEQ calculations this 25 percent reduction is

equivalent to a PM-10 emission reduction of 51.3 lbs/day and a 24-hour

PM-10 ambient reduction of 20 g/m3.

Based upon the surveys conducted in Ada County/Boise, the support

by Pinehurst City officials and the recent success during the 1992-1993

and 1993-1994 wood burning seasons in preventing PM-10 concentrations

from exceeding the 24-hour NAAQS, EPA is satisfied that at least a 25

percent emission reduction is occurring when voluntary episodic wood

burning curtailments are declared in Pinehurst. Therefore, EPA is

accepting the 25 percent credit claimed for this control measure.

Further description of this program and justification for EPA's action

is set out in the TSD, contained in the public record corresponding

with this action.

(2) Public Awareness Program. The wood smoke public awareness

program for the Pinehurst/Silver Valley area plays a critical role in

ensuring that the residential wood combustion program is successful.

Public awareness of the problems associated with wood smoke has a

significant effect on how well the different components of the wood

smoke control program are accepted. IDEQ has utilized the following

methods to promote public awareness about the wood smoke problem in

Pinehurst: education brochures for each household, utility bill

inserts, newspaper articles--public service announcements (PSA's),

educational materials for elementary schools, surveys to determine the

level of awareness and response to programs, radio interviews, radio

PSA's, outreach to wood stove dealers and wood/pellet fuel outlets, and

Speakers Bureau through service clubs and community meetings. IDEQ's

well-established public awareness program was enhanced in 1991, when

$14,550 was awarded by the Pacific Northwest and Alaska Bioenergy

Program to provide wood energy education in Idaho's Silver Valley

(which includes Pinehurst). For the 1993-1994 and 1994-1995 residential

heating seasons, a wood stove advocate has been hired by IDEQ to serve

as an information outlet regarding wood stove issues and also track the

progress of reducing wood stove emissions.

IDEQ is claiming a five percent credit for the Pinehurst wood smoke

public awareness program. This credit is based upon the increased

effectiveness of the public awareness program since 1991, the fact that

Pinehurst is a small town (population 1,722 in 1990)--which makes it

relatively easy to keep in contact with the citizens, and the fact that

IDEQ has hired a Pinehurst wood stove advocate to work on increasing

the public's awareness of the availability of cleaner-burning

residential heating devices.

Considering IDEQ's aforementioned reasons for claiming a five

percent emission reduction credit (which equals a PM-10 emission

reduction of 10.8 lbs/day, and a 24-hour PM-10 ambient reduction of 4

g/m3), EPA is accepting the five percent credit requested

by the IDEQ.

(3) Uncertified Wood Stove Change-out Program. IDEQ is in the

process of replacing 90 uncertified wood stoves in the Pinehurst

nonattainment area with cleaner heating devices. The uncertified wood

stoves are replaced as part of a combined Federal assistance grant, and

State and local loan program. Ninety grants ranging from $500-$1,750

each will be offered to the residents of Pinehurst as financial

incentive to replace their uncertified stoves with natural gas

furnaces, pellet stoves or phase II wood stoves. In addition, 50 of

these participants will be offered low interest loans, up to a maximum

amount of $1,500 per homeowner, using Idaho Department of Water

Resources (IDWR) funds. These loans will cover the additional costs of

upgrading the qualifying resident's heating system, including the cost

of installation. IDWR will allow the loans to be paid back over a five-

year period. The combined grant and loan program will be administered

by the Northern Idaho Community Action Agency (NICAA).

It is estimated by IDEQ that the combined grant/loan program will

replace 90 uncertified wood stoves with 40 natural gas furnaces, 25

pellet stoves and 25 phase II wood stoves. This change is projected to

result in a PM-10 emission reduction of 43.4 lbs/day (which equals a 17

g/m3 24-hour PM-10 reduction) in the Pinehurst

nonattainment area (based upon a 100%, 95% and 55% emission reduction

credits for replacing uncertified wood stoves with natural gas

furnaces, pellet stoves and phase II wood stoves, respectively; a 0.56

lbs/day PM-10 emission rate for a uncertified wood stove in Pinehurst;

and the determination that a PM-10 emission rate of 393 lbs/day equals

a 24-hour ambient PM-10 concentration of 150 g/m3 at

Pinehurst).

Thus, IDEQ is estimating that the wood stove change-out program

will reduce PM-10 emissions from residential wood combustion devices in

Pinehurst by 16.5 percent (or 43.4 lbs of PM-10 reduced/day divided by

263.8 lbs of PM-10 emitted on the worst case day in 1994). EPA believes

that the program will reduce PM-10 emissions in the Pinehurst

nonattainment area because the program is receiving broad based support

and has secure funding sources. Therefore, EPA is accepting the 16.5

percent PM-10 emission reduction credit that IDEQ claims will result

from implementation of the wood stove change-out program.

(4) Home Weatherization Program. Wood stove emissions can be

reduced slightly through comprehensive weatherization programs that

result in a reduction of the amount of fuel utilized. The Idaho

Economic Opportunity Office offers free weatherization assistance to

low income families. This assistance takes the form of an energy audit,

which may result in insulation, weather stripping and heating system

improvements.

Home weatherization improvements will be applied to all 90

households in which wood stove change-outs occur, using loans and grant

money from Idaho Department of Water Resources, Farmers Home

Administration, Washington Water Power and North Idaho Community Action

Agency's Weatherization Division. At least 30 other homes will be

targeted for weatherization improvements.

EPA's Guidance Document for Residential Wood Combustion Emission

Control Measures, September 1989, generally recommends less than a five

percent credit for home weatherization programs. However, IDEQ is

claiming an eight percent credit for the Pinehurst home weatherization

program for the following three reasons: a. Pinehurst has a higher than

normal percentage of older, uninsulated homes; b. Shoshone County,

which contains Pinehurst, has a high percentage of low income

households, who in the past were unable to afford weatherization; and

c. Pinehurst's cold winter climate results in a high number of heating

degree days, which enables a home weatherization program to have more

impact than it would in an area that possesses a warmer winter climate.

The eight percent reduction claimed from the program is only

equivalent to a PM-10 decrease of 3.5 lbs/day (which equals a daily

ambient PM-10 reduction of 1 g/m3). Therefore, this

program will have only a slight impact on PM-10 levels during worst

case days. Nonetheless, in light of IDEQ's reasoning that homes in

Pinehurst are in need of weatherization, and that weatherizing 120

homes will result in lower fuel consumption and correspondingly less

PM-10 emissions in the Pinehurst nonattainment area, EPA is accepting

the eight percent credit claimed by IDEQ.

b. Other Sources. RACM (including RACT) does not require the

imposition of controls on emissions from sources that are insignificant

(i.e. de minimis) and does not require the implementation of all

available control measures where an area demonstrates timely attainment

and the implementation of additional controls would not expedite

attainment (see 57 FR 13540-44).

IDEQ has determined, through its emission inventory analysis of the

nonattainment area, that road dust contributed 38 percent of the PM-10

concentration on the worst case days in base year 1988. IDEQ

demonstrated timely attainment of the 24-hour PM-10 NAAQS by

controlling wood smoke. Therefore, RACM does not require road dust

control measures. Furthermore, RACM does not require the implementation

of controls for prescribed silvicultural and agricultural burning for

the Pinehurst nonattainment area, because the area is not significantly

impacted by those activities on worst case days, according to the

emission inventory analysis.

Similarly, RACT does not require the implementation of control

technology for sources of PM-10 in the nonattainment area, because the

area is primarily characterized by residential and commercial uses

which are not subject to RACT requirements. There are no major

stationary sources operating in the Pinehurst PM-10 nonattainment area.

A more detailed discussion of the control measures contained in the

SIP and an explanation as to why certain available control measures

were not implemented, can be found in IDEQ's submittal and in the TSD.

EPA has reviewed IDEQ's submittal and associated documentation and

concluded that they adequately justify the control measures to be

implemented. The implementation of the Pinehurst, Idaho PM-10

nonattainment plan control strategy will result in the attainment of

the PM-10 NAAQS as expeditiously as practicable--by December 31, 1994.

By this notice, EPA is approving IDEQ's control strategy as satisfying

the RACM (including RACT) requirement.

4. Demonstration

Moderate PM-10 nonattainment areas must submit a demonstration

(including air quality modeling) showing that the plan will provide for

attainment as expeditiously as practicable but no later than December

31, 1994 (see section 189(a)(1)(B) of the Act). The General Preamble

sets out EPA's guidance on the use of modeling for moderate area

attainment demonstrations (57 FR 13539). Alternatively, the State must

show attainment by December 31, 1994, is impracticable. The 24-hour PM-

10 NAAQS is 150 micrograms/cubic meter (g/m3), and the

standard is attained when the expected number of days per calendar year

with a 24-hour average concentration above 150 g/m3 is

equal to or less than one (see 40 CFR 50.6). The annual PM-10 NAAQS is

50 g/m3, and the standard is attained when the expected

annual arithmetic mean concentration is less than or equal to 50

g/m3 (id.).

IDEQ utilized an attainment demonstration for Pinehurst based upon

proportional rollback modeling supported by a complete emission

inventory, receptor modeling and WYNDvalley, a non-guideline dispersion

model.

The receptor modeling consisted of using the Chemical Mass Balance

(CMB) version 7.0 air quality model to analyze for days during 1988-

1990 when 24-hour PM-10 concentrations were either elevated or exceeded

the NAAQS. CMB results from ten PM-10 filters showed that on the

average residential wood smoke and fugitive dust were responsible for

77 and 18 percent, respectively, of the PM-10 on high concentration

days. The CMB percentages for residential wood smoke and fugitive dust

are greater and lower, respectively, than those that were determined

from the emission inventory, but the CMB analysis still confirms that

residential wood combustion is the major source of PM-10 on worst case

days in the Pinehurst nonattainment area. Therefore, these results

support IDEQ's reliance on wood smoke control strategies to attain the

PM-10 standard.

The IDEQ used version 3.06 of the WYNDvalley dispersion model to

simulate PM-10 concentrations in Pinehurst during a wintertime

stagnation episode. WYNDvalley was chosen because of the model's

ability to handle both the light wind conditions and complex terrain

that significantly help trap PM-10 air pollution in the Pinehurst PM-10

nonattainment area. Also, the WYNDvalley dispersion model was used

because Pinehurst is dominated by area sources (wood smoke and fugitive

road dust) and lacks any major point source impacts. The modeled

stagnation event began on January 20, 1988 and continued through

January 30, 1988. Pinehurst's design value exceedance of 183

g/m3 was measured on January 28, during this stagnant

period. The WYNDvalley model showed that the maximum PM-10 values

occurred at or near the Pinehurst school, agreeing with results found

in the January-March 1989 CMB/saturation study. Therefore, the model

helped verify that the Pinehurst PM-10 monitor is situated in the area

of maximum PM-10 impact.

The attainment demonstration indicates that Pinehurst will attain

the 24-hour PM-10 NAAQS by December 31, 1994, with the maximum 24-hour

concentration predicted to be 143 g/m3 (which is the

result of the proposed control measures reducing the projected 1994

maximum PM-10 emissions from 484.8 to 375.9 lbs/day).

According to EPA's review, which identified incomplete quarterly

data in 1986 and corrected for the use of non-reference PM-10 data in

1986 and 1987 (i.e. Hi-Vol SA321A gravimetric PM-10 sampler), Pinehurst

has never violated the annual arithmetic mean PM-10 standard. The

highest valid three-year annual average at Pinehurst is 46 g/

m3, during 1987-1989, while the lowest three-year average is 36

g/m3, during 1990-1992. Therefore, IDEQ and EPA believe

that because the annual PM-10 standard has never been violated at

Pinehurst, and the 24-hour PM-10 controls have helped reduce annual

concentrations (as evidenced in the downward trend in the annual

average concentrations), it is reasonable to predict that the area will

continue to meet the annual standard and the standard will not be

violated in 1994.

EPA is finding that the modeling analysis is adequate to

demonstrate timely attainment of the PM-10 NAAQS in Pinehurst. The

control strategies used to achieve attainment are summarized in the

section titled ``RACM (including RACT).'' A more detailed description

of the attainment demonstration is contained in the TSD accompanying

this notice.

It should be noted that the 1997 maintenance demonstration,

supplied by IDEQ, shows that Pinehurst will remain in attainment for

both the 24-hour and annual PM-10 NAAQS through 1997. According to

IDEQ's calculations, which were partially based on a 1994 Washington

Water Power residential heating survey for the Pinehurst area, the

maximum 24-hour PM-10 concentration in 1997 will be 127 g/

m3. This 1997 24-hour value is equivalent to a PM-10 emission rate

of 332 lbs/day. Furthermore, the annual arithmetic standard will be

maintained from 1994-2000, with the maximum annual average value of

47.2 g/m3 (occurring in the year 2000). This

aforementioned concentration is equivalent to a PM-10 emission rate of

47.0 tons/year. This 1997 maintenance demonstration satisfies part of

the quantitative milestones/reasonable further progress requirement

(see CAA section 189(c)).

5. Quantitative Milestones and Reasonable Further Progress (RFP)

The PM-10 nonattainment area plan revisions demonstrating

attainment must contain quantitative milestones which are to be

achieved every three years until the area is redesignated attainment

and which demonstrate RFP, as defined in section 171(1), toward

attainment by December 31, 1994 (see section 189(c) of the CAA).

While section 189(c) plainly provides that quantitative milestones

are to be achieved until an area is redesignated attainment, it is

silent in indicating the starting point for counting the first three-

year period or how many milestones must be initially addressed. In the

General Preamble, EPA addressed the statutory gap in the starting point

for counting the three-year milestones, indicating that it would begin

from the due date for the applicable implementation plan revision

containing the control measures for the area (i.e., November 15, 1991

for initial moderate PM-10 nonattainment areas) (see 57 FR 13539).

As to the number of milestones, EPA believes that at least two

milestones must be initially addressed. Thus, submittal to address the

SIP revisions due on November 15, 1991 for the initial moderate PM-10

nonattainment areas must demonstrate that two milestones will be

achieved (First milestone: November 15, 1991 through November 15, 1994;

Second milestone: November 15, 1994 through November 15, 1997).

For the initial PM-10 nonattainment areas that demonstrate

attainment, the emissions reduction progress made between the SIP

submittal (due date of November 15, 1991) and the attainment date of

December 31, 1994 (46 days beyond the November 15, 1994 milestone date)

will satisfy the first quantitative milestone. The de minimis timing

differential makes it administratively impracticable to require

separate milestone and attainment demonstrations (see 57 FR 13539). For

such areas that demonstrate timely attainment of the PM-10 NAAQS, the

second milestone should, at a minimum, provide for continued

maintenance of the standards.\5\

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\5\ Section 189(c) of the Act provides that quantitative

milestones are to be achieved ``until the area is redesignated

attainment.'' However, this endpoint for quantitative milestones is

speculative because redesignation of an area as attainment is

contingent upon several factors and future events. Therefore, EPA

believes it is reasonable for States to initially address at least

the first two milestones. Addressing two milestones will ensure that

the State continues to maintain the NAAQS beyond the attainment date

for at least some period during which an area could be redesignated

attainment. However, in all instances, additional milestones must be

addressed if an area is not redesignated attainment.

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This SIP demonstrates attainment by December 31, 1994 and

maintenance through December 31, 1997, satisfying two milestones.

Therefore, the submittal satisfies the quantitative milestones

currently due. Accordingly, EPA is approving the SIP for Pinehurst

relative to the quantitative milestone requirement.

Finally, once a milestone has passed, the State will have to

demonstrate that the milestone was, in fact, achieved for the Pinehurst

area as provided in section 189(c)(2) of the Act.

6. PM-10 Precursors

The control requirements which are applicable to major stationary

sources of PM-10, also apply to major stationary sources of PM-10

precursors unless EPA determines such sources do not contribute

significantly to PM-10 levels in excess of the NAAQS in that area (see

section 189(e) of the Act). The General Preamble contains guidance

addressing how EPA intends to implement section 189(e) (see 57 FR

13539-13540 and 13541-13542).

The filter analyses (chemical mass balance) indicated that, on

average, less than 4 percent of the PM-10 mass was comprised of

secondary particulate on high concentration days. EPA believes that

this is an insignificant portion and, therefore, is proposing to grant

the exclusion from control requirements authorized under section 189(e)

for major stationary sources of PM-10 precursors.

Note that while EPA is making a general finding for this area about

precursor contribution to PM-10 NAAQS exceedances, this finding is

based on the current character of the area including, for example, the

existing mix of sources in the area. It is possible, therefore, that

future growth could change the significance of precursors in the area.

7. Enforceability Issues

All measures and other elements in the SIP must be enforceable by

IDEQ and EPA (see sections 172(c)(6), 110(a)(2)(A) of the CAA and 57 FR

13556). EPA criteria addressing the enforceability of SIP's and SIP

revisions are set forth in a September 23, 1987 memorandum (with

attachments) from J. Craig Potter, Assistant Administrator for Air and

Radiation, et. al. (see 57 FR 13541). Nonattainment area plan

provisions must also contain a program that provides for enforcement of

the control measures and other elements in the SIP (see section

110(a)(2)(C) of the CAA).

The particular control measures contained in the SIP are addressed

above under the section headed ``RACM (including RACT).'' These control

measures apply to residential wood combustion activities. The SIP

provides that the control measures for the affected activities apply

throughout the entire nonattainment area.

The SIP provided that all affected activities would be in full

compliance with the implementation of applicable control measures by

December 10, 1993. However, funding problems has delayed implementation

of the wood stove change-out and home weatherization programs until the

summer of 1994.

IDEQ is responsible for running the voluntary episodic wood burning

curtailment and public awareness programs. The curtailment program for

Pinehurst is part of a statewide program that evaluates air quality and

meteorological parameters in the PM-10 nonattainment areas on a daily

basis, during November 1 through the end of February, and declares

burning bans as necessary. The public awareness program is a broad-

based strategy designed for the entire Silver Valley (which includes

the Pinehurst NAA). IDEQ, through the Pinehurst Particulate (PM-10) Air

Quality Improvement Plan and supporting documentation, commits to

carrying out the curtailment and public awareness programs in

Pinehurst. If either of these two measures are discontinued without EPA

and public approval, then the State of Idaho would be subject to a

findings letter for non-implementation of an approved part of the plan

(see section 179(a)(4) of the CAA). This in turn could result in

Federal sanctions imposed against the State and the loss of State base

grant funds.

IDEQ's submittal and the TSD contain further information on

enforceable requirements. The TSD also contains a discussion of the

personnel and funding intended to support effective implementation of

the control measures.

8. Contingency Measures

As provided in section 172(c)(9) of the Act, all moderate

nonattainment area SIP's that demonstrate attainment must include

contingency measures (see generally 57 FR 13543-13544). These measures

were required to be submitted by November 15, 1993 for the initial

moderate nonattainment areas. Contingency measures should consist of

other available measures that are not part of the area's control

strategy. These measures must take effect without further action by the

State or EPA, upon a determination by EPA that the area has failed to

make RFP or attain the PM-10 NAAQS by the applicable statutory

deadline.

Contingency measures for the Pinehurst PM-10 nonattainment area

have not yet been submitted by IDEQ. A findings letter, dated January

13, 1994, was mailed to the Governor of Idaho which informed him that

the State had failed to make the required PM-10 contingency measures

submittal for Pinehurst. The State has until July 13, 1995 to correct

this deficiency for Pinehurst, or it will face federal highway or

offset sanctions (see section 179 of the CAA).

EPA intends to take action on the contingency measures for the

Pinehurst PM-10 nonattainment area when the requirement is submitted,

or intends to impose sanctions in the event this deficiency is not

corrected.

III. Implications of This Action

EPA is approving the plan revision submitted to EPA on April 14,

1992 for the Pinehurst nonattainment area. Among other things, IDEQ has

demonstrated that the Pinehurst moderate PM-10 nonattainment area will

attain the PM-10 NAAQS by December 31, 1994.

IV. Administrative Review

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.

SIP approvals under section 110 and subchapter I, part D of the CAA

do not create any new requirements, but simply approve requirements

that the state is already imposing. Therefore, because the federal SIP-

approval does not impose any new requirements, I certify that it does

not have a significant impact on any small entities affected. Moreover,

due to the nature of the federal-state relationship under the CAA,

preparation of a regulatory flexibility analysis would constitute

federal inquiry into the economic reasonableness of state action. The

CAA forbids EPA to base its actions concerning SIPs on such grounds.

Union Electric Co. v. U.S.E.P.A., 427 U.S. 246, 256-66 (S.Ct. 1976); 42

U.S.C. 7410(a)(2).

The EPA is publishing this action without prior proposal because

the Agency views this as a noncontroversial amendment and anticipates

no adverse comments. However, in a separate document in this Federal

Register publication, the EPA is proposing to approve the SIP revision

should adverse or critical comments be filed. This action will be

effective October 24, 1994 unless, by September 26, 1994 adverse or

critical comments are received.

If the EPA receives such comments, this action will be withdrawn

before the effective date by publishing a subsequent document that will

withdraw the final action. All public comments received will be

addressed in a subsequent final rule based on this action serving as a

proposed rule. The EPA will not institute a second comment period on

this action. Any parties interested in commenting on this action should

do so at this time. If no such comments are received, the public is

advised that this action will be effective October 24, 1994.

The EPA has reviewed this request for revision of the federally

approved SIP for conformance with the provisions of the 1990 Clean Air

Act Amendments enacted on November 15, 1990. The EPA has determined

that this action conforms with those requirements.

Nothing in this action should be construed as permitting or

allowing or establishing a precedent for any future request for

revision to any SIP. Each request for revision to the SIP shall be

considered separately in light of specific technical, economic and

environmental factors and in relation to relevant statutory and

regulatory requirements.

This action has been classified as a Table 2 action by the Regional

Administrator under the procedures published in the Federal Register on

January 19, 1989 (54 FR 2214-2225), as revised by an October 4, 1993

memorandum from Michael H. Shapiro, Acting Assistant Administrator for

Air and Radiation. The OMB has exempted this regulatory action from

E.O. 12866 review.

Under section 307(b)(1) of the Clean Air Act, petitions for

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

of Appeals for the appropriate circuit by October 24, 1994. Filing a

petition for reconsideration by the Administrator of this final rule

does not affect the finality of this rule for the 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), 42 U.S.C.

7607(b)(2)).

List of Subjects in 40 CFR Part 52

Environmental protection, Air pollution control, Incorporation by

reference, Particulate matter.

Dated: July 5, 1994.

Gerald A. Emison,

Acting Regional Administrator.

Part 52, chapter I, title 40 of the 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 N--Idaho

2. Section 52.670 is amended by adding paragraph (c)(28) to read as

follows:

Sec. 52.670 Identification of plan.

* * * * *

(c) * * *

(28) On April 14, 1992, the State of Idaho submitted a revision to

the SIP for Pinehurst, ID, for the purpose of bringing about the

attainment of the national ambient air quality standards for

particulate matter with an aerodynamic diameter less than or equal to a

nominal 10 micrometers.

(i) Incorporation by reference.

(A) April 7, 1992 letter from Idaho Department of Health and

Welfare to EPA Region 10 submitting the Pinehurst Particulate Air

Quality Improvement Plan as a revision to the Implementation Plan for

the Control of Air Pollution in the State of Idaho. The plan has been

adopted in accordance with the authorities and requirements of the

Federal Clean Air Act and the Idaho Environmental Protection and Health

Act (Idaho Code section 39-10/et seq).

(B) SIP revision for Pinehurst Particulate Air Quality Improvement

Plan, February 5, 1992 (adopted on April 7, 1992).

[FR Doc. 94-20810 Filed 8-24-94; 8:45 am]

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