[Federal Register Volume 59, Number 183 (Thursday, September 22, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-23496]


[[Page Unknown]]

[Federal Register: September 22, 1994]


=======================================================================
-----------------------------------------------------------------------

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[ID 1-1-5528; FRL-5076-9]

 

Approval and Promulgation of State Implementation Plans: Idaho

AGENCY: Environmental Protection Agency.

ACTION: Notice of proposed rulemaking.

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

SUMMARY: The Environmental Protection Agency (EPA) proposes to take 
action on the state implementation plan (SIP) submitted by the State of 
Idaho Division of Environmental Quality (State or IDEQ) 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) in the Ada 
County/Boise area. The SIP was submitted by the State to satisfy 
certain Federal requirements for an approvable moderate nonattainment 
area PM-10 SIP for Ada County/Boise, Idaho.
    In summary, EPA proposes to grant full approval of the emissions 
inventory and PM-10 precursor exclusion elements of the SIP because 
they are separable and independent elements. EPA proposes limited 
approval under sections 110(k)(3) and 301(a) of the Clean Air Act (CAA) 
of the control measures that have been submitted by the State to date. 
This limited approval of the control measures is for the limited 
purpose of making them federally enforceable and thereby advancing the 
Clean Air Act NAAQS-related air quality goals. At the same time, EPA is 
proposing to disapprove the control measures as not satisfying the 
specific requirement under sections 172(c)(1) and 189(a)(1)(C) of the 
CAA to submit a SIP revision that includes provisions to assure that 
reasonably available control measures (RACM) are implemented no later 
than December 10, 1993 and to disapprove the attainment demonstration 
and quantitative milestones and reasonable further progress (RFP) 
elements of the Ada County/Boise PM-10 SIP because the State has not 
adopted and submitted to EPA the mandatory wood smoke control 
ordinances for Eagle, Garden City, Meridian and unincorporated Ada 
County.

DATES: Comments on this proposed action must be received in writing by 
October 24, 1994.

ADDRESSES: Written comments should be addressed to: Montel Livingston, 
United States Environmental Protection Agency, Air Programs Development 
Section, 1200 Sixth Avenue, AT-082, Seattle, Washington, 98101.

FOR FURTHER INFORMATION CONTACT: Stephen Fry, United States 
Environmental Protection Agency, Air Programs Development Section, 1200 
Sixth Avenue, AT-082, Seattle, Washington, 98101, (206) 553-2575.

SUPPLEMENTARY INFORMATION:

I. Background

    The Ada County/Boise, 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). 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 today's rulemaking action on the State of Idaho's 
moderate PM-10 SIP for the Ada County/Boise nonattainment area, EPA is 
proposing to apply 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. EPA will consider any timely submitted 
comments before taking final action on today's proposal.
---------------------------------------------------------------------------

    \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 (CAA or Act). 
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.
---------------------------------------------------------------------------

    Those States containing initial moderate PM-10 nonattainment areas 
(those areas designated nonattainment under section 107(d)(4)(B) of the 
Act) were required to submit, among other things, the following 
provisions by November 15, 1991:
    1. Provisions to assure that 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 Act). 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 IDEQ that the NSR program submittal 
was complete. EPA is currently reviewing Idaho's NSR program submittal 
to determine if the program meets the requirements of the CAA. EPA 
intends to take action on Idaho's NSR program in a separate document 
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) of the Act and 57 FR 13510-13512 and 13543-13544). 
Contingency measures for the Ada County/Boise 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 Ada County/Boise. The State has until July 13, 1995 to 
correct this deficiency for Ada County/Boise, 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 Ada County/Boise 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 submittals (see 57 FR 13565-13566). In this action, as 
described below, EPA is proposing to grant full approval of the 
emission inventory element and exclusion from the PM-10 precursor 
control requirements. These elements of the State's moderate PM-10 
nonattainment SIP submittal for Ada County/Boise are separable and 
independent of the provisions that the State has not adequately 
addressed.
    Also as described below, EPA is proposing to grant a limited 
approval of the control measures that have been submitted by the State 
as of this date. EPA may grant a limited approval of these control 
measures under section 110(k)(3) of the Act, in light of EPA's 
authority under section 301(a) of the Act to adopt regulations 
necessary to further air quality by strengthening the SIP. The proposed 
approval of these control measures is limited, however, in that EPA is 
not proposing that these control measures satisfy the specific 
requirements of sections 172(c)(1) and 189(a)(1)(C) to implement RACM, 
including RACT, in moderate PM-10 nonattainment areas. EPA believes, 
however, that the control measures adopted and submitted as of this 
date will achieve PM-10 emissions reductions in the Ada County/Boise 
nonattainment area. Thus, EPA is proposing to approve these control 
measures for the limited purpose of strengthening the SIP and making 
them federally enforceable (see e.g. sections 113 and 302(q) of the 
Act).
    Finally, because the State has not yet adopted into the SIP and 
submitted to EPA certain control measures on which it relies in the SIP 
to demonstrate timely attainment and continued maintenance of the PM-10 
NAAQS in the Ada County Boise nonattainment area, EPA is proposing to 
disapprove the RACM (including RACT) element. In addition, because the 
attainment demonstration and quantitative milestones and reasonable 
further progress (RFP) elements of the Ada County/Boise PM-10 SIP 
depend in part on the control measures which the State has not yet 
adopted and submitted to EPA, EPA is also proposing to disapprove these 
elements. If this proposed disapproval becomes final, it will begin the 
period for the imposition of discretionary sanctions under section 
110(m) of the Act and the 18-month sanctions clock for the imposition 
of mandatory sanctions under section 179 of the Act. If finalized, this 
disapproval will also authorize EPA to issue a Federal implementation 
plan as provided in section 110(c)(1) of the Act.
    If, however, prior to EPA's final action on this proposal the State 
submits the additional control measures on which it relies and, based 
on EPA's review, these additional control measures adequately address 
the outstanding deficiencies, EPA will consider withdrawing this 
limited approval/disapproval and will instead propose full approval of 
the PM-10 plan for Ada County/Boise relative to those moderate area PM-
10 SIP requirements which were due November 15, 1991. EPA invites 
public comment on its proposed action.

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.
---------------------------------------------------------------------------

    \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).
---------------------------------------------------------------------------

    EPA also must determine whether a submittal is complete and 
therefore warrants further EPA review and action (see section 110(k)(1) 
of the Act 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 IDEQ initially held a public hearing on the Ada County/Boise 
PM-10 air quality improvement plan on October 11, 1990, and received no 
public comments regarding the plan. However, following one 24-hour PM-
10 exceedance on January 7, 1991 and two near exceedances on January 4 
and 6, 1991, EPA requested on March 22, 1991 that IDEQ modify the PM-10 
plan to better ensure healthful air in the future. IDEQ revised the PM-
10 plan and the State of Idaho subsequently held a public hearing on 
the modified Ada County/Boise PM-10 plan on November 4, 1991. Again, 
IDEQ received no public comments. The modified PM-10 plan was then 
adopted by the State of Idaho on November 14, 1991, and the plan was 
submitted to EPA on November 15, 1991 as a proposed 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 April 
27, 1992 was forwarded to the Administrator of the Idaho Division of 
Environmental Quality indicating the completeness of the submittal and 
the next steps to be taken in the review process.
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 e.g. section 110(a)(2)(K) of the Act). 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 
demonstration submission (see 57 FR 13539).
    The base year emission inventory (1987) developed for Ada County/
Boise identified the major sources of PM-10 concentrations during 24-
hour worst case winter periods as residential wood combustion (71%), 
fugitive road dust (15%), industrial (7%) and other sources, including 
but not limited to, transportation, construction and open burning (7%). 
Annual emissions for 1987 were fugitive road dust (51%), residential 
wood combustion (23%), building construction (12%), transportation 
(6%), industrial (6%) and other sources (2%).
    EPA is proposing to approve 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 Full 
approval of this element is appropriate because it is separable and 
independent of the deficiency which prevents full approval of the SIP, 
namely, the adoption and submission of all control measures on which 
the State relies in the SIP. The emissions inventory is a separable 
component of the Ada County/Boise PM-10 SIP because it represents an 
assessment of PM-10 emissions in the area prior to the adoption of 
control measures and will not change as the result of any additional 
control measures adopted. For further details, see the Technical 
Support Document (TSD) corresponding with this action, which is 
available at the EPA address indicated above.
---------------------------------------------------------------------------

    \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 (see section 
193 of the Act).
---------------------------------------------------------------------------

3. Control Measures
    As noted above, the initial moderate PM-10 nonattainment areas must 
submit provisions to assure that RACM (including RACT) are implemented 
no later than December 10, 1993 (see sections 172(c)(1) and 
189(a)(1)(C) of the Act). 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).
    In broad terms, the State should identify available control 
measures evaluating them for their reasonableness in light of the 
feasibility of the controls and the attainment needs of the area. A 
State may reject available control measures if the measures are 
technologically infeasible or the cost of the control is unreasonable. 
In addition, RACM does not require controls on emissions from sources 
that are insignificant (i.e. de minimis) and RACM does not require the 
implementation of all available control measures where an area 
demonstrates timely attainment of the NAAQS and the implementation of 
additional controls would not expedite attainment (see 57 FR 13540-
13544).
    Idaho's SIP submittals for Ada County/Boise do not provide for 
implementation of control measures which assure timely attainment of 
the PM-10 NAAQS, nor, in the alternative, do they show that the 
adoption of available control measures would be economically or 
technologically unreasonable. Therefore, the submittals do not meet the 
specific statutory requirements to provide for the implementation of 
RACM (including RACT) in moderate PM-10 nonattainment areas.
a. Residential Wood Burning Program
    The State relies on control strategies designed to reduce wood 
smoke for timely attainment of the 24-hour and annual PM-10 standards. 
The residential wood burning program has three main objectives: 1. 
Reduce wood burning during critical periods; 2. Improve the performance 
and efficiency of wood heating equipment; and 3. Provide reasonable 
alternatives to wood heat. The State's available control measures to be 
implemented in the Ada County/Boise nonattainment area that address the 
main objectives include the following:
(1) Episodic Wood Burning Curtailment Program
    The SIP submittal discusses an episodic two-stage voluntary and 
mandatory wood burning curtailments in the Ada County/Boise 
nonattainment area. The first stage is a voluntary burn ban when 24-
hour PM-10 levels in the nonattainment area are predicted to equal or 
exceed 100 g/m\3\. The 24-hour PM-10 prediction is made after 
an IDEQ meteorologist calculates lower atmospheric stability and 
evaluates PM-10 equivalent sampler, nephelometer, upper air temperature 
sounding, snow cover, surface temperature, delta temperature, wind 
speed, cloud cover, National Weather Service and occasionally 
commercial weather service data.
    The second stage is a mandatory curtailment program. In 1986, Boise 
adopted an ordinance imposing a mandatory burn ban when 24-hour PM-10 
levels actually attain or exceed 110 g/m\3\, and stable 
meteorological conditions are expected to persist for the next 24 hours 
(see Boise City Code, Tit. 4, Ch. 6). This ordinance was amended in 
January 1993 to reduce the trigger point for mandatory burn bans from 
110 g/m\3\ to 100 g/m\3\ (see Boise City Code, Sec. 
4-6-4).
    The SIP states that Garden City also has a mandatory curtailment 
program, but no documentation of the Garden City program was included 
in the initial SIP submittal. The SIP further states that the State 
would attempt to persuade other Ada County jurisdictions to implement 
mandatory curtailment programs similar to the Boise program. To date, 
EPA has informally received copies of mandatory wood smoke curtailment 
ordinances (some are signed and others are unsigned) for unincorporated 
Ada County and the cities of Eagle, Garden City and Meridian. These 
ordinances, however, have not been adopted into the SIP and have not 
been formally submitted to EPA.
    In its SIP submittal, the State notes that a county-wide5 
mandatory wood smoke curtailment program is necessary to bring the Ada 
County/Boise nonattainment area into timely attainment of the NAAQS 
because approximately 30% of the wood burning in the area occurs 
outside of areas covered by mandatory wood burning restrictions. For 
this reason, the SIP submittal for Ada County/Boise cannot be 
considered to satisfy the RACM requirement because the State has not 
adopted as part of the SIP and submitted to EPA those available control 
measures necessary for expeditious attainment of the PM-10 NAAQS (or 
shown that all economically and technologically feasible control 
measures have been implemented and timely attainment is impracticable). 
Specifically, the State has not adopted and submitted mandatory burn 
ban ordinances for Garden City, Eagle, Meridian and unincorporated Ada 
County. EPA urges the State to promptly adopt and submit to the EPA the 
necessary mandatory residential wood smoke burning ban ordinances on 
which the State relies in its SIP submittal.
---------------------------------------------------------------------------

    \5\In a letter to the EPA, dated August 14, 1992, the State 
argued for the exclusion of the locality south of Amity Road and 
west of Cloverdale Road (the Kuna area) from proposed mandatory burn 
bans because the area is located in a separate stream drainage from 
the Boise River Valley, and thus does not significantly contribute 
smoke to the valley where the PM-10 exceedances have been recorded. 
The State also noted that the emission inventory, modeling and 
visibility observations indicate that the Kuna area air quality is 
markedly cleaner than the ambient air in the Boise River Valley, 
which includes downtown Boise. EPA acknowledged in an August 27, 
1992 letter to IDEQ, that the State had adequately demonstrated that 
mandatory burn bans in the Kuna area were unnecessary to demonstrate 
attainment and EPA formally proposes to make this determination in 
today's action.
---------------------------------------------------------------------------

    Although the SIP submittal cannot be considered to satisfy the RACM 
requirement at this time, EPA is proposing limited approval of the 
Boise wood smoke control ordinance, Boise City Code Tit. 4, Ch. 6, 
pursuant to sections 110(k)(3) and 301(a) of the Act in order to 
strengthen the SIP and make the ordinance federally enforceable. EPA 
believes that this control measure will result in reductions in PM-10 
emissions in the nonattainment area and thus advance the Act's air 
quality-related protection goals.
(2) Wood Smoke Public Education/Awareness Program
    The wood smoke public education/awareness program for the Ada 
County/Boise nonattainment area plays a critical role in achieving the 
aforementioned three main objectives of IDEQ's residential wood burning 
program. The wood smoke public education/awareness program was first 
officially initiated in 1986, following the passage of Boise's local 
wood burning ordinance. Brochures, television and radio public service 
announcements, newspaper advertisements, outreach meetings at public 
schools, media interviews and press conferences are the main components 
of the integrated awareness package. Various points have been focused 
on during the program's existence, including the nature of the wood 
smoke problem, health impacts, meteorological factors (including tips 
asking citizens to refrain from burning on clear, calm and/or cool 
days) and how to burn cleaner.
    IDEQ and the City of Boise are responsible for a majority of the 
continuing wood smoke public education/awareness program. According to 
IDEQ, local surveys and building department statistics show reductions 
in the numbers of wood stoves installed, reduction in the average 
volume of wood burned per household and widespread public cooperation 
during poor air quality periods as the result of the wood smoke public 
education efforts. These surveys and statistics are the basis for the 
10% annual credit IDEQ is claiming for the wood smoke public education/
awareness program during 1990 through the year 2000.
    EPA believes that IDEQ has adequately demonstrated, through surveys 
and building department statistics, that the well-established, 
extensive, wood smoke public education/awareness program for the Ada 
County/Boise PM-10 nonattainment area has achieved at least a 10 
percent wood smoke emission reduction. Therefore, EPA proposes limited 
approval of the wood smoke public education/awareness program described 
in the Ada County/Boise SIP as a SIP strengthening measure and proposes 
to accept the 10 percent credit requested by the IDEQ.
(3) Wood Stove Certification
    The City of Boise's 1986 wood burning ordinance initiated a 
requirement mandating all wood burning appliances sold and installed 
within the city to be certified as meeting certain emission standards 
(see Boise City Code, Sec. 4-6-9). The ordinance is enforced by city 
and county building department inspectors. The initial certification 
program was based on the Oregon Department of Environmental Quality 
standards. The current program is based on the national wood burning 
device New Source Performance Standards developed by the EPA.
    The implementation and enforcement of the certification program 
resulted in the City of Boise accelerating the introduction of 
certified stoves and the phase-out of old, high emission uncertified 
stoves. However, IDEQ does not take any credit for the emission 
reductions that have resulted from the wood stove certification 
program.6
---------------------------------------------------------------------------

    \6\According to the SIP submittal, Meridian, Eagle, Garden City, 
unincorporated Ada County, Nampa and Emmett also require that only 
certified wood stoves be sold and installed within their respective 
jurisdictions. However, no documentation (i.e. ordinances) 
supporting this statement was included in the SIP submittal.
---------------------------------------------------------------------------

    Based upon the enforceability of the City of Boise wood stove 
certification program and its advancement of the PM-10 air quality 
goals, EPA is proposing limited approval of this program as a SIP 
strengthening measure.
(4) Wood Stove Change-Out Program
    An initial feature of the City of Boise's 1986 wood burning 
ordinance was the development of a financial incentive program to 
replace uncertified wood stoves with certified stoves (see Boise City 
Code, Sec. 4-6-18). Low or no interest loans were offered to 
individuals participating in the program. In order to receive a loan, 
the participant was required to give the uncertified wood stove to the 
city building department for destruction. The loan program began in 
September 1986 and ended in September 1988. Approximately $800,000 in 
loans were made, resulting in the replacement of 494 uncertified wood 
stoves with cleaner heating devices. IDEQ does not take credit for 
reductions in the emissions, even though 84 uncertified wood stoves 
were removed from the airshed after the area source emission inventory 
base year (1987).
    The Idaho Department of Water Resources (IDWR) also operated a wood 
stove change-out loan program, which ran from May 1987 to May 1993. 186 
uncertified wood stoves were changed-out with cleaner heating devices 
during that period, with a majority of the replacements occurring 
during 1988-1993. Again, IDEQ did not take credit for these PM-10 
emission reductions. Both the Boise and IDWR wood stove change-out loan 
programs strengthen the SIP and further assure that these wood smoke 
sources will not contribute to a future PM-10 exceedance. Accordingly, 
EPA proposes limited approval of the wood stove change-out loan program 
because it strengthens the SIP and enhances PM-10 air quality 
protection for the Ada County/Boise PM-10 nonattainment area.
b. Other Sources
    As noted, RACM does not require 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 13540-13544).
    IDEQ has determined, through its analysis of the nonattainment 
area, that road dust contributed 15 percent of the PM-10 concentration 
on the worst case day in base year 1987. IDEQ did not propose controls 
for road dust. Rather, the State relies on wood smoke controls to 
demonstrate timely attainment of the 24-hour PM-10 standard, concluding 
that the implementation of additional control measures for road dust 
would not expedite attainment. However, the State's control strategy 
assumes the timely adoption and submittal of effective and enforceable 
mandatory wood smoke curtailment ordinances for the remainder of the 
nonattainment area. While such mandatory wood smoke curtailment 
ordinances, in conjunction with the other wood smoke controls described 
above, may demonstrate attainment of the standard, all of these control 
measures have not in fact been submitted. Thus, RACM is not met because 
it has not been demonstrated that the implementation of available 
control measures could not expedite attainment or that the 
implementation of such measures is technologically or economically 
unreasonable.
    It is EPA's view that RACM does not require the implementation of 
controls for prescribed silvicultural and agricultural burning for the 
Ada County/Boise nonattainment area because the area is not 
significantly impacted by those activities. Similarly, EPA believes 
that RACT does not require the implementation of control technology for 
stationary sources of PM-10 in the nonattainment area, because the area 
is primarily characterized by commercial, residential and light 
industrial uses. There are currently no major stationary sources 
operating in the Ada County/Boise PM-10 nonattainment area and large 
stationary sources do not contribute significantly to the PM-10 air 
quality problem in Boise.
    In summary, EPA is proposing to approve, under the authority of 
sections 110(k)(3) and 301(a) of the Act and for the limited purpose of 
strengthening the SIP and making such control measures federally 
enforceable, the control measures that have been submitted to date as 
part of the PM-10 SIP for the Ada County/Boise nonattainment area. 
These measures include the voluntary episodic wood burning curtailment 
program for the entire nonattainment area, the mandatory episodic wood 
burning curtailment program for the City of Boise, the wood smoke 
public education/awareness program, the wood stove certification 
program and the wood stove change-out program. A final limited approval 
of these existing control measures would not mean that EPA has approved 
these control measures as satisfying the specific Act requirement for 
the State to implement RACM (including RACT) in moderate PM-10 
nonattainment areas (see sections 172(c)(1) and 189(a)(1)(C)). Rather, 
limited approval of these measures by EPA means only that these control 
requirements become part of the applicable implementation plan and are 
federally enforceable by EPA (see, e.g., sections 302(q) and 113 of the 
Act). EPA is concurrently proposing to disapprove the RACM (including 
RACT) element because the State has not adopted and submitted to EPA 
all of the mandatory wood smoke control ordinances on which it relies 
in its SIP submittal. A final disapproval of the Ada County/Boise PM-10 
SIP RACM (including RACT) element would start the 18 month clock for 
the imposition of mandatory sanctions under section 179 of the Act and 
the two-year clock for the promulgation of a Federal Implementation 
Plan under section 110(c)(1) of the Act.
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.).
    As indicated in the General Preamble, 57 FR 13539, EPA has 
developed a supplemental attainment demonstration policy for initial 
PM-10 nonattainment areas. This policy provides additional flexibility 
in meeting the PM-10 attainment demonstration requirements. An earlier 
April 2, 1991 memorandum titled, ``PM-10 Moderate Area SIP Guidance: 
Final Staff Work Product'' contained ``Attachment 5'' describing the 
same policy.
    IDEQ conducted an attainment demonstration based upon WYNDvalley, a 
non-guideline dispersion model that EPA recommended be used in the Ada 
County/Boise nonattainment area. WYNDvalley is applicable in light and 
variable wind scenarios in regions influenced by complex terrain. Cold 
temperatures and light winds with limited vertical mixing create 
stagnant weather conditions in the Boise River Valley. All of the PM-10 
exceedances observed in the Ada County/Boise nonattainment area have 
occurred during stagnant wintertime conditions.
    The attainment demonstration indicates that the Ada County/Boise 
nonattainment area will be in attainment of the 24-hour PM-10 NAAQS 
during the entire period of 1993 to 2000, with the maximum predicted 
24-hour concentration of 147 g/m3 occurring in 1995. The 
demonstration also addresses the quantitative milestone requirement 
(discussed below) by showing that the PM-10 NAAQS will be maintained 
after December 31, 1994 by predicting a 24-hour worst case day design 
concentration of 144 g/m3 for the year 2000. According to 
EPA's review, which corrected for the use of non-reference PM-10 data 
in 1986 and 1987 (i.e. Hi-Vol SA321A gravimetric PM-10 sampler), the 
Ada County/Boise area has never violated the annual arithmetic mean PM-
10 standard. The highest valid three-year annual average in the 
nonattainment area is 43 g/m3 during 1987-1989, while the 
lowest three-year average is 39 g/m3 during 1990-1992.
    The control strategy used to achieve these design concentrations 
and demonstrate attainment of both the 24-hour and annual PM-10 
standards, however, relies on mandatory wood smoke control programs in 
Eagle, Garden City, Meridian and unincorporated Ada County. As 
discussed above in the section titled ``Control Measures,'' the State 
has not adopted these ordinances as part of the SIP and submitted them 
to EPA. Accordingly, EPA proposes to disapprove the attainment 
demonstration. More detailed description of the attainment 
demonstration is contained in the TSD accompanying this document.
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) of the Act, 
toward attainment by December 31, 1994 (see section 189(c) of the CAA).
    Although 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, submittals 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 (1st milestone: November 15, 1991 through November 15, 1994; 
2nd milestone: November 15, 1994 through November 15, 1997). For areas 
that demonstrate timely attainment of the PM-10 NAAQS, the second 
milestone should, at a minimum, provide for continued maintenance of 
the standards.\7\
---------------------------------------------------------------------------

    \7\Section 189(c) provides that quantitative milestones are to 
be achieved ``until the area is redesignated attainment.'' However, 
this endpoint for quantitative milestones is speculative because 
redesignation for 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.
---------------------------------------------------------------------------

    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). In 
implementing the quantitative milestone and RFP provisions for this 
initial moderate area, EPA has reviewed the attainment demonstration 
for the area to determine the nature of any milestones necessary to 
ensure timely attainment and whether annual incremental reductions 
should be required in order to ensure attainment of the PM-10 NAAQS by 
December 31, 1994.
    The SIP purports to demonstrate attainment by 1994 and maintenance 
through 2000, which would satisfy three milestones. However, as 
discussed above, the maintenance demonstration and, therefore, the 
quantitative milestones directly depend on mandatory wood smoke control 
programs in Eagle, Garden City, Meridian and unincorporated Ada County. 
As discussed above in the section titled ``Control Measures,'' the 
State has not adopted these ordinances as part of the SIP and submitted 
them to EPA. Accordingly, EPA proposes to disapprove the quantitative 
milestone requirement (see General Preamble, 57 FR 13565 and July 9, 
1992 EPA memorandum regarding ``Processing of State Implementation Plan 
(SIP) Submittals'').
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).
    Because the emission inventory for the Ada County/Boise PM-10 
nonattainment area did not reveal any major stationary sources, 
including any major stationary sources of PM-10 precursors, EPA is 
proposing to grant the exclusion from control requirements authorized 
under section 189(e) for major stationary sources of PM-10 precursors.
7. Enforceability Issues
    All measures and other elements in the SIP must be enforceable by 
IDEQ and EPA (see sections 172(c)(6) and 110(a)(2)(A) of the Act and 57 
FR 13556). EPA criteria addressing the enforceability of SIP's and SIP 
revisions were 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)).
    The specific control measures that were submitted as part of the 
SIP are addressed above under the section headed ``Control Measures.'' 
As also discussed in that section, although the State relies on 
mandatory wood smoke control ordinances throughout the entire 
nonattainment area (except for the Kuna area) to demonstrate attainment 
and maintenance of the standard, the State has adopted and submitted to 
EPA a mandatory wood smoke curtailment ordinance only for the City of 
Boise. The necessary ordinances for Eagle, Garden City, Meridian and 
unincorporated Ada County, as well as evidence that the wood smoke 
control programs for these areas are adequately funded, implemented, 
enforced and maintained, have not been submitted at this time.
    EPA has reviewed for enforceability the wood smoke ordinance for 
the City of Boise, which includes the mandatory curtailment program and 
the wood stove certification program for Boise, and has determined that 
it meets all of the criteria included in the September 23, 1987, Potter 
Memorandum. Exemptions from the mandatory burn bans are allowed only 
for the following reasons and must be approved by the City Building 
Department: a. wood burning is the resident's sole source of heat; b. 
curtailment would cause unreasonable economic hardship for low income 
households; or c. the wood burning device being utilized is certified 
by the Oregon Department of Environmental Quality or EPA as ``clean 
burning''. This is consistent with the recommendations for woodburning 
curtailment programs provided in EPA's Guidance Document for 
Residential Wood Combustion Emission Control Measures. The wood stove 
certification program does not contain any exemptions. Compliance with 
wood burning curtailments and the certification program is mainly 
achieved by responding to citizen complaints, but the City of Boise has 
limited personnel that independently monitor for noncompliance. 
Enforcement of burn bans and the certification program follows three 
progressive steps: 1. written warning; 2. fine; and 3. further legal 
action against the violator, if needed. IDEQ's submittals and the TSD 
contain further information on the enforceability of the Boise wood 
smoke curtailment ordinance and the personnel and funding intended to 
support effective implementation of this ordinance. In these respects, 
this control measure appears to be enforceable.
    Section 110(a)(2)(E) of the Act requires that, where the State has 
relied on a local or regional government, agency or instrumentality for 
the implementation of any plan provision, the plan must provide 
necessary assurances that the State has responsibility for ensuring 
adequate implementation of such plan provision. The State's initial SIP 
submittal did not address the requirement of section 110(a)(2)(E). 
However, in a recent submission from the State addressing State 
responsibility for local control measures, such as the Boise wood smoke 
control ordinance, the State indicated that it relies on its existing 
ability to issue an operating permit to any stationary source when the 
Department determines that emission reductions from that source are 
necessary to attain or maintain a NAAQS (see Idaho Administrative 
Procedures Act (IDAPA) 16.01.01012.03.c (June 1993); IDAPA 
16.01.01401.03 (May 1994)). The submission includes a copy of an 
opinion from the Attorney General's office stating that such permits 
could be issued to the owners of wood stoves and could include 
provisions directly implementing local mandatory wood smoke curtailment 
ordinances in the event a local entity fails to implement or enforce 
its respective local ordinance. This mechanism appears to satisfy the 
requirements of section 110(a)(2)(E) of the Act for State 
responsibility for local wood smoke control ordinances.
    EPA is reserving judgment on the enforceability of the outstanding 
control measures (i.e. mandatory wood smoke curtailment programs for 
Eagle, Garden City, Meridian and unincorporated Ada County) and the 
adequacy of the related enforcement programs until EPA receives and 
reviews these 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 13510-13512 and 13543-13544). 
These measures must have been 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 
core 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 reasonable further progress or attain the PM-10 
NAAQS by the applicable statutory deadline.
    Contingency measures for the Ada County/Boise 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 informing him 
that the State had failed to make the required PM-10 contingency 
measures submittal for the Ada County/Boise SIP. The State has until 
July 13, 1995 to correct this deficiency for Ada County/Boise, or it 
will face Federal highway and/or offset sanctions (see section 179 of 
the CAA).
    EPA intends to take action on the contingency measures for the Ada 
County/Boise PM-10 nonattainment area when this requirement is 
submitted or intends to impose sanctions in the event this deficiency 
is not corrected.
9. Transportation Conformity Protective Finding
    Section 176(c)(4) of the CAA and the regulations implementing that 
provision require that transportation plans, programs, and projects 
which are funded or approved under title 23 U.S.C. or the Federal 
Transit Act must conform with State or Federal air quality 
implementation plans (see 58 FR 62188 (November 24, 1993)). According 
to 58 FR 62228, Sec. 51.448, areas which submitted a control strategy 
implementation plan before November 24, 1993 must be demonstrated to 
conform according to transitional period criteria and procedures by 
November 25, 1994. Otherwise, their conformity status will lapse, and 
no new project-level conformity determinations may be made. Under 40 
CFR 51.448(a)(2),\8\ if EPA disapproves a control strategy 
implementation plan revision submitted by the State and notifies the 
State, the Metropolitan Planning Organization (MPO), and the Department 
of Transportation (DOT), the conformity status of the transportation 
plan and transportation improvement program (TIP) lapses 120 days after 
EPA's disapproval. After that time, no new project-level conformity 
determinations may be made and no new transportation plan, TIP, or 
project may be found to conform until another control strategy 
implementation plan revision is submitted and conformity is 
demonstrated according to transitional period criteria and procedures. 
Note that these conformity consequences of a disapproval of a control 
strategy are in addition to the discretionary sanctions, which may be 
imposed under section 110(m) of the Act at any time following a 
disapproval, and the mandatory sanctions, which must be imposed under 
section 179 of the Act beginning 18 months following a disapproval.
---------------------------------------------------------------------------

    \8\Although Secs. 51.448(d) (2) and (3) by their terms apply to 
``areas which submitted a control strategy implementation plan 
before November 24, 1993,'' the effective date of the conformity 
rule, EPA intended that these provisions apply only to plans on 
which final action had been taken prior to the effective date of the 
rule. EPA intended the provisions of Sec. 51.448(a) (2) and (3) to 
apply to all plans, regardless of the date of submission, on which 
final action was not taken until after November 24, 1993. In other 
words, EPA intended that the conformity status of the transportation 
plan and TIP lapse 120 days or, in the case of a protective finding, 
one year after the later of the effective date of the conformity 
rule (November 24, 1994) or the disapproval of the control strategy.
---------------------------------------------------------------------------

    Section 51.448(a)(3), however, allows EPA to extend the 120-day 
lapse period to one year from the date of disapproval if EPA determines 
that the control strategy contained in the revision would have been 
considered approvable with respect to requirements for emission 
reductions if all committed measures had been submitted in enforceable 
form as required by section 110(a)(2)(A) of the Act. If EPA makes such 
a ``protective finding,'' the transportation conformity plan and TIP 
will be valid for 12 months following the date of disapproval and the 
conformity status of the transportation plan and TIP will lapse 12 
months following the date of disapproval unless within that time 
another control strategy implementation plan revision is submitted to 
EPA and found to be complete.
    If, as proposed in this action, EPA disapproves the control 
strategy in the moderate area SIP for the Ada County/Boise 
nonattainment area, under Sec. 51.448(a)(2) the conformity status of 
the transportation plan and TIP would lapse 120 days after the 
effective date of the disapproval. EPA has evidence, however, that the 
wood smoke control ordinances for the cities of Eagle, Garden City and 
Meridian, and unincorporated Ada County are enforceable as a matter of 
local law, and believes that these control measures would have been 
considered approvable with respect to requirements for emission 
reductions if each of these control measures had been submitted to EPA 
in enforceable form as required by section 110(a)(2)(A). Therefore, EPA 
proposes that the 120-day lapse period be extended to one year under 40 
CFR 51.448(a)(3). Accordingly, if EPA takes final action on this 
proposal, and the RACM (including RACT) requirement, attainment 
demonstration and quantitative milestones and RFP elements of the Ada 
County/Boise moderate PM-10 nonattainment SIP are disapproved, then the 
State of Idaho's transportation plan and TIP may be found to conform 
for 12 months past the effective date of the PM-10 SIP disapproval. The 
conformity status of the transportation plan and TIP would then lapse 
12 months following the effective date of final action on this proposal 
unless within that time another control strategy implementation plan 
revision is submitted to EPA and found to be complete.

III. Implications of This Action

    EPA is proposing to approve the emission inventory and, as 
described in the TSD, several submittals to address requirements of 
section 110(a)(2) of the Act, including the: a. Monitoring network (CAA 
section 110(a)(2)(B)); b. consultation and public notification/process 
(CAA section 110(a)(2)(J); c. provisions for revising the plan (CAA 
section 110(a)(2)(H)); and d. prohibiting sources from significantly 
impacting other states (CAA section 110(a)(2)(D)). EPA is also 
proposing to grant the exclusion from precursor control requirements 
authorized under section 189(e) of the Act. EPA is proposing limited 
approval of the control measures that have been submitted by the State 
as of this date under the authority of sections 110(k)(3) and 301(a) of 
the Act for the limited purpose of strengthening the SIP and making 
them federally enforceable. EPA believes making these control measures 
federally enforceable will achieve PM-10 emissions reductions in the 
Ada County/Boise nonattainment area and, therefore, advances the NAAQS-
related goals of the CAA. EPA is proposing disapproval of these control 
measures as meeting the RACM (including RACT) requirement, because the 
State has not adopted as part of the SIP and submitted to EPA those 
available control measures necessary for expeditious attainment of the 
PM-10 NAAQS (or shown that all economically and technologically 
feasible control measures have been implemented and timely attainment 
is impracticable), specifically, mandatory burn ban ordinances for 
Garden City, Eagle, Meridian and unincorporated Ada County. In 
addition, because the attainment demonstration and quantitative 
milestones and reasonable further progress (RFP) elements of the Ada 
County/Boise PM-10 SIP depend in part on the control measures which the 
State has not yet adopted and submitted to EPA, EPA is also proposing 
to disapprove these elements.
    A final disapproval of these Ada County/Boise PM-10 SIP elements 
will authorize the imposition of discretionary sanctions under section 
110(m) of the Act, and will institute the 18-month clock for the 
imposition of mandatory sanctions under section 179 of the Act and the 
two-year clock for the promulgation of a Federal Implementation Plan 
under section 110(c)(1) of the Act.
    If, however, the State submits the additional control measures on 
which it relies in its SIP submittal and, based on EPA's review, these 
additional control measures adequately address the outstanding 
deficiencies, EPA will consider withdrawing this limited approval/
disapproval and instead proposing full approval of the PM-10 plan for 
Ada County/Boise relative to those moderate area PM-10 SIP requirements 
which were due November 15, 1991.

IV. Request for Public Comments

    EPA is requesting comments on all aspects of this proposal. As 
indicated at the outset of this document, EPA will consider any 
comments postmarked by October 24, 1994.

V. Administrative Review

    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 2214-2224), 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.
    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.
    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 economic 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 sections 110 and 301 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 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 
(see 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)). EPA's disapproval of the State request 
under section 110 and subchapter I, part D of the CAA does not affect 
any existing requirements applicable to small entities. Any pre-
existing Federal requirements remain in place after this disapproval. 
Federal disapproval of the State submittal does not affect its state-
enforceability. Moreover, EPA's disapproval of the submittal does not 
impose any new Federal requirements. Therefore, EPA certifies that this 
disapproval action does not have a significant impact on a substantial 
number of small entities because it does not impose any new Federal 
requirements.

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

List of Subjects in 40 CFR Part 52

    Environmental protection, Air pollution control, Incorporation by 
reference, Intergovernmental relations, Particulate matter, Reporting 
and recordkeeping requirements.

    Dated: September 13, 1994.
Jane S. Moore,
Acting Regional Administrator.
[FR Doc. 94-23496 Filed 9-21-94; 8:45 am]
BILLING CODE 6560-50-P