[Federal Register Volume 61, Number 193 (Thursday, October 3, 1996)]
[Proposed Rules]
[Pages 51631-51638]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-25230]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[CO-001-002; CO-001-003 and CO-001-004; FRL-5628-8]


Clean Air Act Approval and Promulgation of PM10 
Implementation Plan for Denver, CO, and the Denver Mobile Source 
Emissions Budgets for PM10 and NOX

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice of proposed rulemaking.

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SUMMARY: EPA proposes approval of the state implementation plan (SIP) 
revision submitted by Colorado on March 30, 1995, to achieve 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 (PM10) in the Denver area, including: Control 
measures; technical analysis (e.g., emission inventory, and attainment) 
and other Clean Air Act (Act) SIP requirements. The SIP revision was 
submitted to satisfy certain Federal requirements for an approvable 
moderate nonattainment area PM10 SIP for Denver and, among other 
things, contains enforceable control measures.
    EPA also proposes to approve the PM10 and NOX mobile 
source emissions budgets for Denver that were submitted by the Governor 
on July 18, 1995 and April 22, 1996, respectively.

DATES: Comments on the actions proposed in this document must be 
received in writing by December 2, 1996.

ADDRESSES: Comments should be addressed to: Richard R. Long, Director, 
Air Program (8P2-A), Environmental Protection Agency, Region VIII, 999 
18th Street, Suite 500, Denver, Colorado 80202-2466. Label the comments 
as comments addressing the Denver PM10, PM10 emissions budget 
or NOX emissions budget SIPs.
    Copies of the State's submittals and other information are 
available for inspection during normal business hours at the following 
locations: Environmental Protection Agency, Region VIII, Air Program, 
999 18th Street, Denver, Colorado 80202-2466; and Colorado Air 
Pollution Control Division, 4300 Cherry Creek Dr. South, Denver, 
Colorado 80222-1530.

FOR FURTHER INFORMATION CONTACT: Callie Videtich, Air Program, EPA 
Region VIII, 999 18th Street, Suite 500, Denver, Colorado 80220-2405 or 
by phone at (303) 312-6434.

SUPPLEMENTARY INFORMATION:

I. Background

    The Denver, Colorado area was designated nonattainment for 
PM10 and classified as moderate under sections 107(d)(4)(B) and 
188(a) of the Act, upon enactment of the Clean Air Act Amendments of 
1990.1 See 56 FR 56694 (Nov. 6, 1991); and 40 CFR 81.306 
(specifying PM10 nonattainment designation for the Denver 
metropolitan area). The air quality planning requirements for moderate 
PM10 nonattainment areas are set out in Part D, Subparts 1 and 4, 
of Title I of the Act.2
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    \1\ The 1990 Amendments to the Clean Air Act made significant 
changes to the Act. See Pub. L. 101-549, 104 Stat. 2399. References 
herein are to the Clean Air Act, as amended (``the 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 PM10 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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    The EPA has issued a ``General Preamble'' describing EPA's 
preliminary views on how EPA intends to review SIPs and SIP revisions 
submitted under Title I of the Act, including those State submittals 
containing moderate PM10 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

[[Page 51632]]

of the interpretations of Title I advanced in this proposal and the 
supporting rationale. In this rulemaking action on the Colorado 
moderate PM10 SIP for the Denver nonattainment area, EPA is 
applying its interpretations considering the specific factual issues 
presented.
    Those States containing initial moderate PM10 nonattainment 
areas (those areas designated nonattainment under section 107(d)(4)(B) 
of the Act) were required to submit, among other things, the following 
plan 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 3 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 PM10 also apply to major stationary 
sources of PM10 precursors except where the Administrator 
determines that such sources do not contribute significantly to 
PM10 levels which exceed the NAAQS in the area. See sections 
172(c), 188, and 189 of the Act.
    Some provisions were due at a later date. States with initial 
moderate PM10 nonattainment areas were required to submit a new 
source review (NSR) permit program for the construction and operation 
of new and modified major stationary sources of PM10 by June 30, 
1992 (see section 189(a)). On January 14, 1993, the State submitted 
regulation revisions for the construction of new and modified major 
stationary sources. On August 18, 1994, EPA partially approved the 
State's NSR program for the Denver PM10 nonattainment area because 
the State had not yet submitted NSR provisions for sources of PM10 
precursors (i.e., NOX and SO2) in the Denver area (see 59 FR 
42300). On August 25, 1994, Colorado submitted additional NSR 
provisions for precursor emissions. EPA will be acting on that SIP 
submittal in a separate notice.
    States were also required to submit contingency measures for 
PM10 moderate nonattainment areas by November 15, 1993. The 
contingency measures for the Denver PM10 nonattainment area were 
initially submitted by the Governor on December 9, 1993. However, those 
measures were later incorporated into the revised March 30, 1995 
PM10 SIP. Therefore, the State developed new contingency measures, 
and on November 17, 1995, the Governor submitted those measures to EPA. 
EPA is taking action on the contingency measures SIP submittal in a 
separate rulemaking action.
    On June 7, 1993, the Governor submitted a SIP for Denver to EPA 
which was intended to satisfy those elements due November 15, 1991. On 
December 20, 1993, EPA proposed to conditionally approve that SIP and 
also proposed to approve the SIP's control measures for their limited 
purpose of strengthening the Colorado SIP (58 FR 66326). On July 25, 
1994, EPA granted limited approval of the control measures for the 
limited purpose of strengthening the SIP (59 FR 37698).
    During review of the technical information supporting the June 1993 
SIP, EPA examined information which raised concern about the accuracy 
of the SIP's attainment demonstration. The SIP's technical support 
documentation suggested that the contribution from PM10 
``precursors'' (i.e., nitrogen oxides and sulfur dioxides) in the base 
year winter season may have been underestimated. Since the attainment 
demonstration provided with that SIP predicted a value of 149.9 
g/m3 over 24 hours, virtually any increase in precursor 
PM10 levels would result in predicted violations of the 24-hour 
standard.
    In the December 20, 1993, proposed rulemaking action, EPA requested 
public comment on it's proposal to grant conditional approval of the 
SIP in light of the precursor issue. EPA reviewed the information 
submitted during the public comment period and concluded that 
precursors were underestimated by 5.4 g/m3. Based upon this 
finding, EPA delayed taking final action on the proposed conditional 
approval to allow the State an opportunity to develop additional 
controls to offset this increase. On March 30, 1995, the Governor 
submitted a SIP revision intended to provide controls to offset the 
increase in precursor emissions and provide credible attainment and 
maintenance demonstrations. On July 18, 1995, and April 22, 1996 the 
Governor submitted additional revisions to the SIP which establish 
mobile source emissions budgets for PM10 and NOX. The 
conformity rule provides that these budgets establish a cap on motor 
vehicle-related emissions which cannot be exceeded by the predicted 
transportation system emissions in the future unless the cap is amended 
by the State and approved by EPA as a SIP revision and attainment and 
maintenance of the standard can be demonstrated.
    Section 110(k) of the Act sets out provisions governing EPA's 
review of SIP submittals (see 57 FR 13565-13566). EPA is taking three 
actions with this document.
    1. EPA is proposing to approve the revised Denver PM10 SIP, as 
adopted by the Colorado Air Quality Control Commission (AQCC) October 
20, 1994 with an amendment on December 15, 1994, and submitted by the 
Governor of Colorado on March 30, 1995. This submittal contains, among 
other things, several control measures, regulation and permit revisions 
and attainment and three-year maintenance demonstrations. The State's 
submittal demonstrates attainment of the PM10 NAAQS by December 
31, 1994 3, with continued maintenance of the standard through 
December 31, 1997.
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    \3\ The Clean Air Act calls for attainment as expeditiously as 
practicable but no later than December 31, 1994. Section 188(c)(1). 
The State's submittal sometimes refers to December 31, 1994 as the 
attainment date and at other times implies 1995 as the attainment 
date. EPA interprets that when the State refers to attainment by 
1995 it means attainment by January 1, 1995. EPA is proposing to 
approve the State's demonstration on the basis of the de minimis 
differential between the two dates and the fact that, at times, the 
State refers to the attainment date as December 31, 1994. The State 
should promptly inform EPA if EPA has in any manner misinterpreted 
the date by which the State is projecting attainment in the Denver 
Metropolitan nonattainment area.
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    2. EPA is proposing to approve the Denver PM10 mobile source 
emissions budget contained in the SIP revision adopted by the AQCC on 
February 16, 1995, and submitted by the Governor on July 18, 1995.
    3. EPA is proposing to approve the Denver NOX mobile source 
emissions budget adopted by the AQCC on June 15, 1995, and submitted by 
the Governor on April 22, 1996.

II. This Action

A. Analysis of March 30, 1995 Denver PM10 SIP 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

[[Page 51633]]

hearing.4 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. The EPA also must determine 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.
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    \4\ In addition, 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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    After providing reasonable notice, the AQCC held a public hearing 
on October 20, 1994, to entertain public comment on the implementation 
plan for Denver. The plan was adopted following the public hearing. The 
plan was further amended after a properly noticed public hearing of the 
AQCC on December 15, 1994. On March 30, 1995, the Governor signed and 
submitted the SIP revision to EPA. The SIP was deemed complete by 
operation of law six months following submission of the plan by the 
Governor.
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.5 The emissions inventory also should include a 
comprehensive, accurate, and current inventory of allowable emissions 
in the area (see, e.g., section 110(a)(2)(K)). Because the submission 
of such inventories is a necessary adjunct of an area's attainment 
demonstration (or demonstration that the area cannot practicably 
attain), the emissions inventories must be received with the SIP 
revision containing the demonstration (see 57 FR 13539).
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    \5\ 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.
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    Colorado submitted an emissions inventory for base year 1989 (based 
on actual emissions) and an emissions inventory for attainment year 
1995 6 (based on allowable emissions). The winter 1989 and 1995 
inventories are intended to represent all sources of primary PM10, 
as well as all sources of the PM10 precursors (nitrogen oxides and 
sulfur dioxide (NOX and SO2)). The precursor emissions are 
important because filter analyses performed in conjunction with 
chemical mass balance modeling indicated that a significant portion 
(35%) of the PM10 monitored consisted of secondary ammonium 
sulfate and nitrate.
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    \6\ See footnote 3.
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    The wintertime 1989 base year inventory identified re-entrained 
road dust (44%), wood burning (18%) and street sanding (8.5%) as the 
principal contributors to primary PM10. Other primary PM10 
sources include unpaved road dust contributing 12.5% and point sources 
contributing 4% of the total primary PM10 inventory.
    The secondary emissions, 35% of total PM10, are divided 
between NOX and SO2. For wintertime 1989 base year NOX, 
stationary sources contribute 40% of the total NOX emissions with 
vehicle exhaust at 41% and natural gas from residential and commercial 
usages at 11%. The prime sources of SO2 include stationary sources 
with 92% of the total SO2 emissions and vehicle exhaust with 5%.
    The wintertime 1995 attainment year inventory identified re-
entrained road dust (47%), wood burning (6%) and street sanding (7%) as 
the principal contributors to primary PM10. Other primary 
PM10 sources include unpaved road dust contributing 12% and point 
sources contributing 9% of the total primary PM10 inventory.
    The secondary emissions, 35% of total PM10, are divided 
between NOX and SO2. For the wintertime 1995 attainment year 
NOX, stationary sources contribute 44% of the total NOX 
emissions with vehicle exhaust at 38% and natural gas from residential 
and commercial usages at 10%. The prime sources of SO2 include 
stationary sources with 97% of the total SO2 emissions and vehicle 
exhaust with 1%.
    EPA is proposing to approve the emissions inventory because it is 
accurate and comprehensive, and provides a sufficient basis for 
determining the adequacy of the attainment demonstration for the Denver 
area consistent with the requirements of sections 172(c)(3) and 
110(a)(2)(K) of the act. For further details see the Technical Support 
Document (TSD) prepared for this action which is available for public 
review at the address indicated at the beginning of this notice.
3. RACM (Including RACT)
    As noted, initial moderate PM10 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)). The General Preamble contains a detailed discussion of 
EPA's interpretation of RACM (including RACT) (see 57 FR 13539-13545 
and 13560-13561).
    On July 25, 1994, EPA took final rulemaking action to approve 
controls found in the June 7, 1993 Denver PM10 SIP submittal. That 
action approved controls for their limited ability to strengthen the 
SIP under sections 110(k)(3) and 301(a) of the Act. In that rulemaking 
action, EPA found that the control measures appeared to satisfy the 
specific requirements to implement RACM/RACT. However, due to the 
State's need to fulfill a commitment to revise two stationary source 
permits and due to the question of whether the attainment demonstration 
was reasonable in light of questions regarding precursor contributions 
to the attainment demonstration, EPA did not take definitive action to 
find that the measures met the RACM/RACT requirements. Following the 
June 1993 submittal, the State fulfilled the commitment, and EPA 
determined that the precursor contribution to the PM10 levels was 
underestimated.
    The March 30, 1995 SIP submittal contains an evaluation of the 
emissions reduction programs found in the June 1993 submittal, and 
enhancements to those programs needed to demonstrate attainment and 
maintenance. These enhancements were needed due to the underestimation 
of the precursor contribution in the June 1993 demonstration. EPA is 
now able to make RACM/RACT determinations for the control programs 
contained in the March 1995 SIP submittal.
    The March 30, 1995 SIP revision identifies four source categories 
as major contributors to the PM10 nonattainment problem in Denver. 
The following Table identifies the source categories and their 
respective control measures implemented across the nonattainment area, 
as well as measures exclusive to the Central Business District (CBD). 
Generally, the CBD is where exceedances of the standard have occurred 
and, therefore, is an important focus for the implementation of some of 
the control measures.
    When comparing the 1989 base year actual emissions inventory to the 
1995 attainment year allowable emissions inventory for the entire 
nonattainment area there is actually an increase in PM10 
emissions. This is due to the fact that the suburban area of Denver has 
grown over the past several years. Nevertheless, the State demonstrates 
timely attainment area-wide even with these emissions increases.

[[Page 51634]]

    To show timely attainment of the standard, woodburning controls, 
street sanding/sweeping controls and reductions in stationary source 
emissions had to be developed. As a result of these controls, as well 
as the other control strategies (described further in the TSD), the CBD 
shows a total 9.45% reduction (269.7 tons/year) from base year 1989 
(actuals) to the 1995 attainment year (allowables), and demonstrates 
timely attainment of the standard.

                                       Denver PM10 SIP Control Strategies                                       
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                            Source category                                         Control strategy            
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Residential Wood Burning (Area-wide controls).........................  1. High pollution day wood burning      
                                                                         restriction program and revisions.     
                                                                        2. Requirements that new or remodeled   
                                                                         construction use a new cleaner wood    
                                                                         burning approach.                      
                                                                        3. Voluntary conversion program from    
                                                                         existing wood burning to cleaner       
                                                                         burning technology.                    
                                                                        4. New stove/fireplace insert           
                                                                         certification.                         
                                                                        5. Prohibit resale of used, uncertified 
                                                                         stoves.                                
Street Sanding and Sweeping of Paved Streets (Area-wide and CBD         1. Material specifications for street   
 controls).                                                              sanding material.                      
                                                                        2. Local management plans.              
                                                                        3. Enhanced street sanding and sweeping 
                                                                         in Central Denver and the I-25         
                                                                         Corridor.                              
                                                                        4. City/County of Denver and CDOT reduce
                                                                         amount of street sanding material in   
                                                                         the Denver CBD and central Denver by   
                                                                         50% from base year 1989.               
                                                                                                                
Stationary Sources (Area-wide controls)...............................  1. Emission limits at Purina Mills.     
                                                                        2. Emission limits at Electron          
                                                                         Corporation.                           
                                                                        3. Regulation limits for precursor      
                                                                         emissions at Cherokee, Arapahoe and    
                                                                         Valmont power plants.                  
                                                                        4. Emission limits for NOX and SO2 at   
                                                                         Coors Glass and Coors Brewery.7        
                                                                        5. Emission limits at Conoco Refining.  
                                                                        6. Restrictions on oil use.             
Mobile Sources (Area-wide controls)...................................  1. Light duty vehicle, light duty truck 
                                                                         NOX standards.                         
                                                                        2. Urban bus particulate standards.     
                                                                        3. Diesel fuel sulfur limits.           
                                                                        4. Regulation #11 Enhanced I/M.         
                                                                        5. Regulation #12 Diesel I/M.           
                                                                        6. Regulation #13 Oxy Fuels.            
                                                                        7. MAC light rail line.                 
                                                                        8. Express bus service from Denver to   
                                                                         new Denver International Airport.      
                                                                        9. CommuterCheck program.               
                                                                        10. ECOPass.                            
                                                                        11. CU Student bus pass.                
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\7\ Emission limits for Coors Glass increase, while the limits for Coors Brewery decrease. While EPA believes   
  these revisions to the emissions limits are acceptable for meeting RACM/RACT requirements, EPA's proposed     
  action herein regarding these limits does not in any manner relieve these companies of the obligation to      
  comply with any nonattainment NSR permitting requirements that might apply to such changes in emissions       
  limits.                                                                                                       

    A more detailed discussion of the individual source contributions 
and their associated control measures (including available control 
technology) can be found in the TSD. EPA has reviewed the State's 
documentation and proposes to conclude that it adequately justifies the 
control measures that will be implemented. Therefore, by this document, 
EPA is proposing to approve the Denver PM10 plan submitted by the 
Governor on March 30, 1995, as meeting the RACM (including RACT) 
requirement.
4. Demonstration
    As noted, the initial moderate PM10 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). Alternatively, the State must show that attainment by December 
31, 1994, is impracticable. Colorado conducted an attainment 
demonstration using dispersion modeling for primary PM10 and 
proportional rollback modeling analysis for secondary particulate 
concentrations for the Denver area. This demonstration indicates that 
the NAAQS for PM10 will be attained in Denver by December 31, 
1994, at a modeled concentration of 147.8 g/m3 and will 
be maintained in future years. The 24-hour PM10 NAAQS is 150 
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).
    There have never been exceedances of the annual average PM10 
standard in the Denver metro area; therefore, an attainment analysis of 
the annual standard was not performed. Finally, EPA believes that the 
controls adopted to protect the 24-hour standard are sufficient to 
maintain the annual standard. The control strategy used to achieve the 
24-hour standard is summarized in the section above titled ``RACM 
(including RACT).'' For a more detailed description of the attainment 
demonstration and the control strategy, see the TSD accompanying this 
document.
5. PM10 Precursors
    The control requirements which are applicable to major stationary 
sources of PM10, also apply to major stationary sources of 
PM10 precursors unless EPA determines such sources do not 
contribute significantly to PM10 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) (57 FR 13539-13540 and 13541-13542).
    An analysis of air quality and emissions data for the Denver

[[Page 51635]]

nonattainment area demonstrates that exceedances of the PM10 NAAQS 
are attributable both to direct particulate matter emissions from wood 
burning, street sanding/sweeping, mobile sources, and stationary 
sources, and to mobile and stationary source precursor emissions. 
Further, the dispersion and chemical mass balance modeling for base 
year 1989 identified precursor emissions of NOX and SO2 as 
contributing 35% to the ambient PM10 concentration. Consequently, 
major stationary sources of these precursors are required to comply 
with all control requirements of the PM10 nonattainment area plan 
which apply to major stationary sources of PM10 (i.e, RACT for 
moderate areas and NSR permitting control requirements).
    As indicated above, EPA proposes to approve the State's submittal 
as meeting RACM (including RACT). EPA's proposed approval of RACT 
extends to those control requirements applicable to the major 
stationary sources of PM10 precursors. Specifically, EPA proposes 
to find that the emission limits and restrictions on oil use are 
reasonable and approvable because they provide for timely attainment of 
the PM10 NAAQS. Additionally, these measures will help ensure 
maintenance of the NAAQS.
    On August 25, 1994, Colorado submitted NSR provisions for 
precursors in the Denver nonattainment area. EPA is acting on that SIP 
submittal in a separate notice. Further discussion of the data and 
analyses addressing the contribution of precursor sources in this area 
is contained in the TSD accompanying this document.
6. Quantitative Milestones and Reasonable Further Progress (RFP)
    The PM10 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 toward attainment by December 31, 1994 (see 
sections 171(1) and 189(c) of the Act). RFP is defined in section 
171(1) as such annual incremental reductions in emissions of the 
relevant air pollutant as are required by Part D or may reasonably be 
required by the Administrator for the purpose of ensuring attainment of 
the applicable NAAQS by the applicable date.
    In considering the quantitative milestones 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 
PM10 NAAQS by December 31, 1994 (see section 171(1) of the Act). 
EPA is proposing to approve the PM10 SIP for the Denver 
nonattainment area as demonstrating attainment by December 31, 1994. 
EPA is also proposing to approve the submittal as satisfying the 
initial quantitative milestone requirement 8 and proposes to find 
that the emissions reductions projected meet RFP.
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    \8\ The emissions reduction progress made prior to the 
attainment date of December 31, 1994 (only 46 days beyond the 
November 15, 1994 milestone date) will satisfy the first milestone 
requirement (57 FR 13539). The de minimis timing differential makes 
it administratively impracticable to require separate milestone and 
attainment demonstrations.
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    Further, the State has demonstrated that continued maintenance of 
the standard will be achieved through implementation of the control 
measures found in the SIP. The State's roll-forward analysis indicated 
that the highest predicted concentration is 149.9 g/m3. 
Concentrations over 150 g/m3 violate the NAAQS.
    The assurance that the initial milestone and reasonable further 
progress will be achieved is based upon the State implementing the 
particular control measures contained in the SIP which are addressed in 
section II. A. 3. ``RACM (including RACT)'' of this document. 
Consequently, EPA is approving these control measures as meeting RACM 
(including RACT) and thus is also proposing to approve the SIP as 
meeting the initial milestone and reasonable further progress 
requirements.
7. Enforceability Issues
    All measures and other elements in the SIP must be enforceable by 
the State and EPA (see sections 172(c)(6) and 110(a)(2)(A) of the Act 
and 57 FR 13556). The EPA criteria addressing the enforceability of 
SIPs and SIP revisions were stated in a September 23, 1987 memorandum 
(with attachments) signed by 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 Act).
    The State of Colorado has a program that will ensure that the 
measures contained in the SIP are adequately enforced. In addition to 
the specific authority cited under descriptions of the control 
measures, the State's Attorney General has provided an opinion citing 
the authorities contained in the Colorado Air Pollution Prevention and 
Control Act which provide the State with the authority to enforce state 
air regulations against local entities, and enforce local air pollution 
requirements when local entities fail to do so. This is consistent with 
section 110(a)(2)(E) of the Act.
    The Air Pollution Control Division (APCD) has the authority to 
implement and enforce all emission limitations and control measures 
adopted by the AQCC, as provided for in C.R.S. 25-7-111. In addition, 
C.R.S. 25-7-115 provides that the APCD shall enforce compliance with 
the emission control regulations of the AQCC, the requirements of the 
SIP, and the requirements of any permit. Civil penalties of up to 
$15,000 per day per violation are provided for in C.R.S. 25-7-122 for 
any person in violation of these requirements, and criminal penalties 
are provided for in C.R.S. 25-7-122.1. Thus, the APCD has adequate 
enforcement capabilities to ensure compliance with the Denver PM10 
SIP and the State-wide regulations.
    The particular control measures contained in the SIP apply to the 
types of activities identified earlier and in the following discussion, 
including: residential wood burning; street sanding/sweeping; mobile 
sources; and reductions of emissions from stationary sources. As 
explained in the following discussion, the control measures are 
enforceable. Accordingly, EPA is proposing to approve the control 
measures. The TSD contains further information about enforceability 
requirements, including a discussion of the personnel and funding 
intended to support effective implementation of the control measures.
    a. Residential Wood Burning Controls. 1. High Pollution Day Wood 
Burning Restrictions: Regulation No. 4 requires the APCD to implement 
and enforce wood burning restrictions in areas which did not have local 
enforceable ordinances before January 1, 1990. To ensure proper 
enforcement, the APCD contracts with local health departments to 
execute the enforcement provisions of the Regulation. In communities 
where local ordinances regulating wood burning were in place prior to 
January 1, 1990, the local government is responsible for enforcement of 
its ordinance, including issuing fines, penalties, warnings, and 
conducting inspections. (Local ordinances cover approximately 85% of 
the Denver metro area.) The State has authority to enforce local 
ordinances in place prior to January 1, 1990, if local governments fail 
to do so.
    2. Clean Wood Burning Technology for New or Remodeled Construction: 
Beginning on January 1, 1993, state law

[[Page 51636]]

requires that new or remodeled fireplaces in new or remodeled 
structures must be gas appliances, electric devices, or low emissions 
fireplace inserts meeting the EPA Phase II New Source Performance 
Standard (NSPS) or State adopted Phase III requirements. (EPA's Phase 
II and Colorado's Phase III requirements are equivalent.) Under the 
law, the fireplace restrictions must be adopted as building code 
revisions by each local government and be enforced through the normal 
code enforcement programs of each community. This requirement became 
effective on January 1, 1993.
    3. Encourage Conversion of Existing Wood Burning Units to Cleaner 
Burning Technology: Legislation passed in 1992, required that the lead 
air quality planning organization (the Regional Air Quality Council) 
develop and implement a financial incentive program to provide 
subsidies toward the purchase of new cleaner technologies. 
Additionally, retailers must report the number of purchases of 
certified stoves or inserts, and gas or electric fireplaces to the 
Colorado Department of Revenue and submit a $1 fee for each 
certification of conversion. Under the program, the Department of 
Revenue is responsible for tracking conversions to cleaner 
technologies, reported by retailers, and reporting the status of the 
conversion program to the AQCC.
    4. New Stove and Fireplace Insert Certification: State law 
prohibits the resale and/or installation of any uncertified wood 
burning device in the metro Denver area after January 1, 1993. The law 
is enforced through the building code provisions of the various local 
governments within the Denver area.
    b. Street Sanding and Cleaning Controls. 1. Material Specifications 
for Street Sanding Material: Regulation No. 16 sets specifications for 
fines and durability of new and recycled sanding materials, and 
requires that sand providers and users conduct testing and report the 
quality of sanding materials and amounts used during the winter season 
to the APCD. The Regulation is enforced through authority provided to 
the State by statute.
    2. Local Management Plans: Regulation No. 16 requires State and 
local agencies that apply street sand to develop and submit a plan for 
reducing their use of sand by 20% from 1989 base year levels. The 
agencies are required to adopt ordinances or resolutions to support the 
plans, to submit the plans by September 30, 1993, and to implement the 
plans by November 1, 1993. The agencies are also required to submit 
annual reports to the APCD documenting the reductions in sand use 
achieved through implementation of the plans. The Regulation is 
enforced through authority provided to the State by statute.
    3. Further Enhancements to Street Sanding and Sweeping Practices in 
the Denver CBD and Central Denver Area: Regulation No. 16 also requires 
that the City and County of Denver reduce the amount of street sanding 
material applied to all regional arterials, principal arterials and 
main arterials within the Denver CBD by a total of 50 percent from 1989 
base sanding amounts for these roadways. The revision also requires 
that the Colorado Department of Transportation (CDOT) increase its 
reduction in applied street sanding material from 20 percent to an 
equivalent 50 percent on state-maintained freeways and ramps within the 
Denver CBD. CDOT and the City/County are allowed to implement an 
alternative plan to achieve an equivalent reduction through increased 
sweeping and use of alternative deicers and/or sanding material, 
subject to review and approval by APCD. EPA will review and concur by 
letter on the alternative plans prior to APCD approval. EPA will not 
consider such plans valid absent EPA concurrence. The Regulation is 
enforced through authority provided to the State by statute.
    c. Mobile Source Emission Reduction Measures. The SIP contains a 
variety of mobile source control measures included in the 1990 Clean 
Air Act Amendments in addition to the street sanding and sweeping 
controls. These mobile source measures include the new light-duty 
vehicle, light-duty truck NOX standards, urban bus particulate 
standards, and diesel fuel sulfur limitations. Particulate emission 
reductions are also incorporated for three existing State programs, the 
enhanced inspection and maintenance program, the diesel inspection and 
maintenance program, and the oxygenated fuels program (Regulations 11, 
12 and 13). These programs were developed independently from the 
PM10 SIP but are included because of their particulate matter 
reduction benefit. The Act-required programs are enforced by the 
federal government while the State regulations are enforced by the 
APCD.
    The SIP also includes a number of transportation control measures 
to slow growth in vehicle miles traveled. These are not measures that 
were developed specifically for the SIP, but measures that are already 
planned or underway in the Denver area and accounted for in the mobile 
source modeling for the attainment year. These measures are assumed to 
be implemented by 1995 and have been included in the transportation 
modeling supporting the attainment and maintenance demonstrations. The 
Regional Transportation District (RTD) is implementing these measures 
through its Transit Development Plan which has been adopted by the RTD 
Board of Directors.
    The measures for which the SIP takes credit within the 
transportation modeling include the MAC Light Rail Line and additional 
express bus service to the new Denver International Airport. Also, 
several programs aimed at attracting new ridership are being 
implemented. These new programs include the CommuterCheck program, 
ECOPass, and the CU Student Pass Program. Through the implementation of 
these and other marketing programs, transit ridership is expected to 
increase by 20% between 1989 and 1995. A complete description of the 
measures included in the SIP is found in section VIII of the SIP.
    The Act requires that all federally funded transportation measures 
be included in a conforming Regional Transportation Plan and 
Transportation Improvement Program (TIP). Because the implementation of 
these measures must conform to the SIP, any changes to the federally 
funded measures included in the attainment demonstration must go 
through a conformity analysis before they can be implemented. The 
existing TIP has been found to conform with the SIP.
    d. Stationary Source Measures. To control emissions from stationary 
sources, APCD enforces both permit limitations and regulations through 
authority provided under State statute. See the discussion under 
section II.D. contained in the TSD for more information on the permit 
and regulation revisions at stationary sources.
    Rules and controls relating to woodburning, street sanding/
cleaning, mobile sources, and stationary sources are in effect now. 
Colorado has a program that will ensure that the measures contained in 
the Denver PM10 SIP are adequately enforced. EPA proposes to find 
that the air enforcement program is adequate. The TSD contains further 
information on enforceability responsibilities, requirements, and 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 SIPs that demonstrate attainment must include 
contingency measures (see

[[Page 51637]]

generally 57 FR 13510-13512 and 13543-13544). These measures must 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 
PM10 NAAQS by the applicable statutory deadline. Colorado chose to 
submit the contingency measures separately from the PM10 SIP 
requirements addressed in this document. The contingency measures for 
the Denver PM10 nonattainment area were initially submitted by the 
Governor on December 9, 1993. However, those measures were later 
incorporated into the revised March 30, 1995 PM10 SIP. Therefore, 
the State developed new contingency measures, and on November 17, 1995, 
the Governor submitted those measures to EPA. EPA is taking action on 
the contingency measures SIP submittal in a separate rulemaking action.

B. Denver PM10 Emissions Budget

    On February 16, 1995, the AQCC adopted the Denver PM10 mobile 
source emissions budget into the Colorado ``Ambient Air Quality 
Standards'' following a properly noticed public hearing. On July 18, 
1995, the Governor submitted a SIP revising certain Chapters of the 
Denver PM10 SIP submitted on March 30, 1995, to include the Denver 
PM10 mobile source emissions budget.
    The EPA must determine whether a submittal is complete and 
therefore warrants further EPA review and action (see section 110(k)(1) 
and 57 FR 13565 and EPA's completeness criteria for SIP submittals set 
out at 40 CFR Part 51, Appendix V). EPA did not make its completeness 
determination within six months of receiving the submission. Thus, the 
submittal was deemed complete by operation of law.
    The Denver mobile source PM10 emissions budgets are being used 
to assess the conformity of transportation plans, transportation 
improvements programs, and where appropriate, federally funded projects 
for the applicable periods indicated. The Denver PM10 mobile 
source emissions budget was set for 1995 (41.2 tons/day), 1996-1997 (44 
tons/day), 1998-2005 (54 tons/day) and 2006 and beyond (60 tons/day). 
(The State was able to demonstrate attainment and maintenance of the 
PM10 standard using the 1995 and 1996-1997 PM10 mobile source 
emissions budgets.) The State adopted the PM10 revisions to the 
Ambient Air Standards Emissions Budget to make them state enforceable. 
EPA is proposing that the PM10 emissions budgets are approvable. 
(See the TSD prepared for this action for more information.)

C. Denver NOX Emissions Budget

    On April 22, 1996, the Governor submitted a SIP which contained an 
amendment to the Colorado ``Ambient Air Quality Standards.'' The 
amendment incorporated the NOX emissions budget for the Denver 
PM10 nonattainment area and was adopted by the AQCC following a 
properly held public hearing on June 15, 1995.
    EPA reviewed the documentation as provided in accordance with 
section 110(k)(1) and 57 FR 13565 and EPA's completeness criteria for 
SIP submittals set out at 40 CFR Part 51, Appendix V. EPA found the 
submittal complete, and advised the Governor of that finding in a 
letter on July 15, 1996.
    The 1995 and beyond NOX budget of 119.4 tons per day was used 
in the March 30, 1995 PM10 SIP. (The State was able to demonstrate 
attainment and maintenance of the PM10 standard using the NOX 
mobile source emissions budget.) The State adopted the NOX 
revisions to the Ambient Air Quality Standards Emissions Budget to make 
it state enforceable. EPA is proposing that the NOX emissions 
budget is approvable. (See the TSD prepared for this action for more 
information.)

III. Proposed Action

    EPA is proposing to approve the following: the revised Denver 
PM10 SIP submitted by the Governor of Colorado on March 30, 1995; 
the Denver PM10 mobile source emissions budget submitted by the 
Governor on July 18, 1995; and the Denver NOX mobile source 
emissions budget submitted by the Governor on April 22, 1996.
    The EPA is requesting comments on all aspects of this proposal. As 
indicated elsewhere in this document, EPA will consider any comments 
received by December 2, 1996 on the appropriateness of the proposed 
approval action on the Denver PM10 SIP, the Denver PM10 
mobile source emissions budget, and the Denver NOX mobile source 
emissions budget.

IV. Executive Order 12866

    This action has been classified as a Table 3 action for signature 
by the Regional Administrator under the procedures published in the 
Federal Register on January 19, 1989 (54 FR 2214-2225), as revised by a 
July 10, 1995, memorandum from Mary Nichols, Assistant Administrator 
for Air and Radiation. The Office of Management and Budget (OMB) has 
exempted this regulatory action from E.O. 12866 review.

V. Regulatory Flexibility

    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 subchapter I, part D of the 
Clean Air Act do not create any new requirements but simply approve 
requirements that the State is already imposing. Therefore, because 
this proposed 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 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 (1976); 42 U.S.C. 7410(a)(2).

VI. Unfunded Mandates

    Under Section 202, of the Unfunded Mandates Reform Act of 1995 
(``Unfunded Mandates Act''), signed into law on March 22, 1995, EPA 
must prepare a budgetary impact statement to accompany any proposed or 
final rule that includes a Federal mandate that may result in estimated 
costs to State, local, or tribal governments in the aggregate; or to 
the private sector, of $100 million or more. Under Section 205, EPA 
must select the most cost-effective and least burdensome alternative 
that achieves the objectives of the rule and is consistent with 
statutory requirements. Section 203 requires EPA to establish a plan 
for informing and advising any small governments that may be 
significantly or uniquely impacted by the rule.
    EPA has also determined that this proposed action does not include 
a Federal mandate that may result in estimated costs of $100 million or 
more to State, local, or tribal governments in the aggregate, or to the 
private sector. This Federal action approves pre-

[[Page 51638]]

existing requirements under State or local law, and imposes no new 
Federal requirements. Accordingly, no additional costs to State, local, 
or tribal governments, or to the private sector, result form this 
action.

List of Subjects in 40 CFR Part 52

    Environmental protection, Air pollution control, Hydrocarbons, 
Intergovernmental relations, Nitrogen dioxide, Particulate matter, 
Reporting and recordkeeping requirements, Sulfur dioxide, Volatile 
organic compounds.

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

    Dated: September 13, 1996.
Patricia D. Hull,
Acting Regional Administrator.
[FR Doc. 96-25230 Filed 10-2-96; 8:45 am]
BILLING CODE 6560-50-P