[Federal Register Volume 68, Number 14 (Wednesday, January 22, 2003)]
[Proposed Rules]
[Pages 2954-2969]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 03-1145]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[NV-040-0067; FRL-7440-5]


Approval and Promulgation of Implementation Plans; Nevada--Las 
Vegas Valley PM-10 Nonattainment Area; Serious Area Plan for Attainment 
of the Annual and 24-Hour PM-10 Standards

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: EPA proposes to approve provisions of the PM-10 State 
Implementation Plan for Clark County, June 2001, (Clark County plan) 
that address attainment of the annual and 24-hour PM-10 national 
ambient air quality standards. We also propose to grant Nevada's 
request to extend the Clean Air Act deadline for attaining the 24-hour 
PM-10 standard in the Las Vegas area from 2001 to 2006.

DATES: Comments on this proposal must be received in writing by 
February 21, 2003. Comments should be addressed to the contact listed 
below.

ADDRESSES: Comments should be mailed to: Karen Irwin, Office of Air 
Planning (AIR-2), EPA Region 9, 75 Hawthorne Street, San Francisco, CA 
94105-3901.
    A copy of docket No. NV-01-03, containing the EPA technical support 
document (TSD) and other material relevant to this proposed action, is 
available for public inspection at EPA's Region 9 office during normal 
business hours. We may charge you a reasonable fee for copying parts of 
the docket. Environmental Protection Agency, Region 9, Air Division, 
Air Planning Office (AIR-2), 75 Hawthorne Street, San Francisco, CA 
94105-3901.
    Copies of the SIP materials are also available for inspection at 
the addresses listed below: Clark County Department of Air Quality 
Management, 500 S. Grand Central Pky, Las Vegas, Nevada 89155. Nevada 
Division of Environmental Protection, 333 West Nye Lane, Carson City, 
Nevada 89710.

Electronic Availability

    This document and the TSD are also available as electronic files on 
EPA's Region 9 Web Page at http://www.epa.gov/region09/air.

FOR FURTHER INFORMATION CONTACT: Karen Irwin, Office of Air Planning 
(AIR-2), U.S. Environmental Protection Agency, Region 9, 75 Hawthorne 
Street, San Francisco, California 94105. (415) 947-4116, email: 
[email protected].

SUPPLEMENTARY INFORMATION:

Table of Contents

I. Summary of Today's Proposal
II. Background to Today's Proposal
    A. PM-10 Air Quality in the Las Vegas Area
    B. Previous Actions on Clark County PM-10 Plans
III. The CAA's Planning Requirements for Serious PM-10 Nonattainment 
Areas
IV. The Clark County Plan's Compliance with the CAA's Requirements 
for Serious PM-10 Nonattainment Areas
    A. Completeness of the SIP Submittals
    B. Adequacy of Transportation Conformity Budgets
    C. Adequate Monitoring Network
    D. Emissions Inventory
    E. Contribution to PM-10 Exceedences of Major Sources of PM-10 
Precursors
    F. Implementation of Best Available Control Measures
    1. Steps 1 and 2: Determination of Significant Sources--Adequate 
Modeling
    2. Step 3: Identification of potential BACM
    3. Step 4: Implementation of BACM and inclusion of MSM for Each 
Significant Source Category
    a. Disturbed Vacant Land
    b. Unpaved Parking Lots
    c. Construction Sites
    d. Paved Road Dust
    e. Unpaved Roads
    f. Race Tracks
    g. Section 0
    G. Applicable SIP Rules
    H. General SIP Requirements and Enforcement of Fugitive Dust 
Rules
    I. Demonstration of Attainment and Attainment Date Extension
    1. Apply for an Extension
    2. Demonstrate the Impracticability of Attainment By December 
31, 2001
    3. Complied With the Commitments and Requirements in the SIP
    4. Include the Most Stringent Measures
    5. Demonstrate Expeditious Attainment
    6. Other Factors That EPA May Consider
    7. Conclusion on the Extension Request
    J. Reasonable Further Progress and Quantitative Milestones
    K. Contingency Measures
    L. Administrative Requirements

I. Summary of Today's Proposal

    First, we propose to approve the provisions in the PM-10 State 
Implementation Plan for Clark County, submitted on July 25, 2001,\1\ 
(``the Clark County serious area plan'' or ``Plan'') that address 
attainment of the annual and 24-hour PM-10 standards.\2\ Our proposed 
actions are based on our initial determination that the Clark County 
serious area plan complies with the Clean Air Act's (CAA or ``the 
Act'') requirements for serious PM-10 nonattainment area plans.
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    \1\ On October 24, 2002, the Nevada Division of Environmental 
Protection submitted to EPA revised versions of Clark County 
sections 90 through 93, dated November 20, 2001, which supersede 
earlier versions submitted with the Plan. Also, on November 19, 
2002, the Nevada Division of Environmental Protection submitted to 
EPA an amendment to the Clark County PM-10 Plan adopted by the Clark 
County Board of Commissioners on November 19, 2002.
    \2\ There are two separate national ambient air quality 
standards for PM-10, an annual standard of 50 [mu]g/m3 
and a 24-hour standard of 150 [mu]g/m3.
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    First, we propose to approve the following specific elements of the 
plan as they pertain to the standards:
    [sbull] Demonstration that the plan provides for implementation of 
best available control measures (BACM);
    [sbull] Emissions inventory;
    [sbull] Demonstration of attainment of the annual standard by the 
CAA deadline of December 31, 2001 and demonstration that attainment of 
the 24-hour standard by December 31, 2001 is impracticable;
    [sbull] Demonstration that attainment of the 24-hour standard will 
occur by the most expeditious alternative date practicable, in this 
case, December 31, 2006;
    [sbull] Clark County fugitive dust rules (Sections 90 through 94 
and portions of Section 0);
    [sbull] Demonstration that the plan provides for reasonable further 
progress and quantitative milestones;
    [sbull] Transportation conformity budget; and
    [sbull] Contingency measures.
    Second, we are proposing to grant Nevada's request to extend the 
attainment date for the 24-hour PM-10 standard from December 31, 2001 
to December 31, 2006. We make this proposal based on our determination 
that the State has met the CAA's criteria for granting such extensions.
    This preamble describes our proposed actions on the Clark County 
serious area

[[Page 2955]]

plan and provides a summary of our evaluation of the plan. Our detailed 
evaluation of the Plan can be found in the TSD that accompanies this 
proposal. See ``Technical Support Document Proposing Approval of the 
PM-10 State Implementation Plan for the Clark County Serious PM-10 
Nonattainment Area Annual and 24-Hour PM-10 Standards,'' December 19, 
2002. A copy of EPA's TSD can be downloaded from our website or 
obtained by calling or writing the contact person listed above.

II. Background to Today's Proposals

A. PM-10 Air Quality in the Las Vegas Area

    The Las Vegas Valley Nonattainment Area, which coincides with 
Hydrographic Basin 212, is roughly 1,500 square miles in size and 
encompasses the City of Las Vegas, the City of North Las Vegas, the 
City of Henderson and the unincorporated areas of Clark County. The 
population of the area is approximately 1.15 million people and is 
expected to grow to 1.59 million by 2006.
    The area violates both the annual \3\ and 24-hour PM-10 standards. 
In 1990, the area was designated nonattainment for PM-10 and classified 
as moderate. In 1993, because of continuing violations of both PM-10 
standards, the area was reclassified to serious and required to provide 
for the implementation of BACM by February 8, 1997. 58 FR 3334 (January 
8, 1993).
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    \3\ However, in a June 2002 letter, the Clark County Department 
of Air Quality Management (DAQM) provides an analysis of PM-10 
microscale sites that demonstrates attainment of the annual standard 
as forecasted in the Clark County Plan as of December 31, 2001. 
While EPA is proposing to approve the Plan's attainment 
demonstration for the annual standard under CAA section 189, our 
action does not include an official finding of attainment of the 
annual standard per CAA section 188.
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    The principal contributors to elevated PM-10 levels in the Las 
Vegas area are fugitive dust sources such as disturbed vacant lots, 
construction sites, unpaved roads and paved road dust. Fugitive dust is 
particulate matter suspended in the air either by mechanical 
disturbance of the surface material or by wind action blowing across 
surfaces.

B. Previous Actions on Clark County PM-10 Plans

    Clark County prepared and submitted a serious area PM-10 plan in 
1997 that EPA proposed to disapprove, along with previously submitted 
plans. 65 FR 37324, June 14, 2000. On December 5, 2000, prior to EPA 
taking final action on its proposed disapproval, the State of Nevada 
withdrew the moderate and serious area plans for Clark County. On 
January 5, 2001, EPA proceeded with a finding of nonsubmittal, 
effective as of December 20, 2000, which began the 18-month time clock 
for mandatory application of sanctions and 2-year time clock for 
promulgation of a federal implementation plan (FIP). 66 FR 1046. On 
June 19, 2001, the Clark County Board of Commissioners adopted a new 
serious area PM-10 plan titled ``PM-10 State Implementation Plan for 
Clark County'' (``Plan''), which was submitted to EPA on July 25, 2001. 
On January 31, 2002, EPA made a completeness finding on the Plan. We 
have also determined that the conformity budgets in the plan are 
adequate. 67 FR 1461, January 11, 2002. Our adequacy determination was 
effective on January 28, 2002.

III. The CAA's Planning Requirements for Serious PM-10 Nonattainment 
Areas

    The Las Vegas area is a PM-10 nonattainment area that has been 
reclassified to serious because it failed to attain by the moderate 
area attainment date of December 31, 1994. Such an area must submit, 
within 18 months of the reclassification, revisions to its 
implementation plan that address the CAA requirements for serious PM-10 
nonattainment areas. CAA section 189(b)(2). These requirements are:
    (a) Assurances that the BACM, including best available control 
technology (BACT) for stationary sources, for the control of PM-10 
shall be implemented no later than 4 years after the area is 
reclassified (CAA section 189(b)(1)(B)); \4\
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    \4\ When a moderate area is reclassified to serious, the 
requirement to implement RACM in section 189(a)(1)(C) remains and is 
augmented by the requirement to implement BACM. Thus, a serious area 
PM-10 plan must, in addition to BACM, provide for the implementation 
of RACM as expeditiously as practicable to the extent that the RACM 
requirement has not been satisfied in the area's moderate area plan. 
However, to the extent that a serious nonattainment area plan 
provides for BACM, we interpret the BACM requirement as generally 
subsuming the RACM requirement (i.e. if we determine that the 
measures are indeed the ``best available,'' we have necessarily 
concluded that they are ``reasonably available'').
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    (b) Assurances that BACT on major stationary sources of PM-10 
precursors shall be implemented no later than 4 years after the area is 
reclassified except where EPA has determined that such sources do not 
contribute significantly to exceedences of the PM-10 standards (CAA 
section 189(e));
    (c) A demonstration (including air quality modeling) that the plan 
will provide for attainment as expeditiously as practicable but no 
later than December 31, 2001 or where the State is seeking an extension 
of the attainment date under section 188(e), a demonstration that 
attainment by December 31, 2001 is impracticable and that the plan 
provides for attainment by the most expeditious alternative date 
practicable (CAA sections 188(c)(2) and 189(b)(1)(A));
    (d) Quantitative milestones which are to be achieved every 3 years 
and which demonstrate reasonable further progress (RFP) toward 
attainment by the applicable attainment date (CAA sections 172(c)(2) 
and 189(c)); and
    (e) A comprehensive, accurate, and current inventory of actual 
emissions from all sources of PM-10 (CAA section 172(c)(3)).
    Serious area PM-10 plans must also include contingency measures to 
be implemented if the area fails to make RFP or attain by its 
attainment deadline. These contingency measures are to take effect 
without further action by the State or the Administrator. CAA section 
172(c)(9).
    Furthermore, serious area PM-10 plans must meet the general 
requirements applicable to all SIPs including reasonable notice and 
public hearing under section 110(l), necessary assurances that the 
implementing agencies have adequate personnel, funding and authority 
under section 110(a)(2)(E)(i) and 40 CFR 51.280, and a description of 
enforcement methods as required by 40 CFR 51.111.
    We have issued a General Preamble \5\ and Addendum to the General 
Preamble \6\ describing our preliminary views on how the Agency intends 
to review SIPs submitted to meet the CAA's requirements for PM-10 
plans. The General Preamble mainly addresses the requirements for 
moderate areas and the Addendum, the requirements for serious areas.
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    \5\ ``State Implementation Plans; General Preamble for the 
Implementation of Title I of the Clean Air Act Amendments of 1990,'' 
57 FR 13498 (April 16, 1992) and 57 FR 18070 (April 28, 1992).
    \6\ ``State Implementation Plans for Serious PM-10 Nonattainment 
Areas, and Attainment Date Waivers for PM-10 Nonattainment Areas 
Generally; Addendum to the General Preamble for the Implementation 
of Title I of the Clean Air Act Amendments of 1990,'' 59 FR 41998 
(August 16, 1994)
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BACM Requirement

    The CAA does not define what level of control constitutes a BACM-
level of control. In guidance, we have defined it to be, among other 
things, the maximum degree of emission reduction achievable from a 
source or source category which is determined on a case-by-case basis, 
considering energy, economic and environmental impacts. Addendum at 
42010. This level of control is

[[Page 2956]]

dependent on the deadline by which BACM must be implemented.\7\
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    \7\ We have long held that an otherwise available measure is not 
reasonable if it cannot be implemented on a schedule that will 
advance the attainment date. See, e.g., 57 FR 13498, 15560 (April 
16, 1992). See also Delaney v. EPA, 898 F.2d 695 (9th Cir. 1990) 
which required the adoption of ``all available control measures'' to 
attain ``as soon as possible'' and not simply all available control 
measures. The most clear example of this is a measure that cannot be 
implemented until after the applicable attainment date.
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    We also considered a BACM-level control as going beyond existing 
RACM-level controls, such as expanding use of RACM (e.g, paving more 
miles of unpaved roads). Addendum at 42013. The word ``best'' implies 
that there should be a greater emphasis on the merits of the measure or 
technology alone and less flexibility in considering other factors. 
Additionally, we believe that BACM should emphasize prevention rather 
than remediation (e.g., preventing track out at construction sites 
rather than simply requiring clean up of tracked-out dirt). Addendum at 
42013.
    The stringency of a control measure is a function of both the 
measure's applicability and its control requirement (i.e., what sources 
in the category are subject to the measure and what does the measure 
require the sources to do to reduce emissions).\8\ Both these elements 
must be specified before the measure's level of control can be 
determined. Thus in setting a BACM, a state must specify both the 
measure's control requirement and its applicability. The control 
requirement alone is not sufficient.
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    \8\ An example: A measure requires all unpaved roads with 
average daily trips (ADT) over 150 be stabilized by either paving, 
graveling, or treating with chemical stabilizers. The control 
requirement here is ``stabilize using one of these three methods: 
paving, graveling, or chemical stabilization'' and the applicability 
is ``all unpaved roads with ADT over 150.''
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    BACM must be applied to each significant (i.e., non-de minimis) 
source category. Addendum at 42011. In guidance, we have established a 
presumption that a ``significant'' source category is one that 
contributes 5 [mu]g/m3 or more of PM-10 to a location of 24-hour 
violation and 1 [mu]g/m3 or more for the annual standard. Addendum at 
42011. However, whether the threshold should be lower than this in any 
particular area depends upon the specific facts of that area's 
nonattainment problem. Specifically, it depends on whether requiring 
the application of BACM on source categories below a proposed de 
minimis level would meaningfully expedite attainment.
    We have outlined in our guidance a multi-step process for 
identifying BACM. Addendum at 42010-42014. The steps are:
    1. develop a detailed emissions inventory of PM-10 sources and 
source categories,
    2. model to evaluate the impact on PM-10 concentrations over the 
standards of the various sources and source categories to determine 
which are significant,
    3. identify potential BACM for significant source categories and 
evaluate their reasonableness, considering technological feasibility, 
costs, and energy and environmental impacts and
    4. provide for the implementation of the BACM or provide a reasoned 
justification for rejecting any potential BACM.
    When the process is complete, the individual measures \9\ should 
then be converted into a legally enforceable vehicle (e.g., a 
regulation or permit process). CAA sections 172(6) and 110(a)(2)(A). 
Also, the regulations or other measures should meet EPA's criteria 
regarding the enforceability of SIPs and SIP revisions. General 
Preamble at 13541.
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    \9\ Here our guidance refers to RACM, however, since BACM builds 
upon RACM, the same principles apply.
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RACM Requirement

    When a moderate area is reclassified to serious, the requirement to 
implement RACM in section 189(a)(1)(C) remains. Thus, a serious area 
PM-10 plan must also provide for the implementation of RACM as 
expeditiously as practicable to the extent that the RACM requirement 
has not been satisfied in the area's moderate area plan.
    However, we do not normally conduct a separate evaluation to 
determine if a serious area plan's measures also meet the RACM 
requirements as interpreted by us in the General Preamble at 13540. 
This is because in our serious area guidance (Addendum at 42010), we 
interpret the BACM requirement, as generally subsuming the RACM 
requirement. Therefore, a separate analysis to determine if the 
measures represent a RACM level of control is generally not necessary. 
Our proposed approval of the Clark County Plan's provisions relating to 
the implementation of BACM is also a finding that the plan provides for 
the implementation of RACM.

The Clean Air Act Requirements for Attainment Date Extensions

    Section 188(e) of the Act allows us to extend the attainment date 
for a serious area for up to five years beyond 2001 if attainment by 
2001 is impracticable. However, before we may grant an extension of the 
attainment date, the State must first:
    1. Apply to us for an extension of the PM-10 attainment date beyond 
2001,
    2. Demonstrate that attainment by 2001 is impracticable,
    3. Have complied with all requirements and commitments applying to 
the area in its implementation plan,
    4. Demonstrate to our satisfaction that its serious area plan 
includes the most stringent measures that are included in the 
implementation plan of any state and/or are achieved in practice in any 
state and are feasible for the area, and
    5. Submit a demonstration of attainment by the most expeditious 
alternative date practicable.
    In determining whether to grant an extension and the appropriate 
length of the attainment date extension, we may consider:
    1. The nature and extent of the nonattainment problem,
    2. The types and numbers of sources or other emitting activities in 
the area (including the influence of uncontrollable natural sources and 
international transport),
    3. The population exposed to concentrations in excess of the 
standard,
    4. The presence and concentration of potentially toxic substances 
in the mix of particulate emissions in the area, and
    5. The technological and economic feasibility of various control 
measures.
    Under the Act, we may grant only one extension for an area and the 
extension cannot be for more than 5 years after 2001; that is, the 
extended attainment date can be no later than December 31, 2006.

IV. The Clark County Plan's Compliance With the CAA's Requirements for 
Serious PM-10 Nonattainment Areas

    The following sections present a condensed discussion of our 
evaluation of the Clark County Plan's compliance with the applicable 
CAA requirements for attaining the annual and 24-hour PM-10 standards. 
Our complete evaluation is found in the TSD for this proposal. A copy 
of the TSD can be downloaded from our website or obtained by calling or 
writing the contact person listed above.

A. Completeness of the SIP Submittal

    CAA section 110(k)(1)(B) requires us to determine if a SIP 
submittal is complete within 60 days of its receipt. This completeness 
review allows us to quickly determine if the submittal

[[Page 2957]]

includes all the necessary items and information we need to take action 
on it. We make completeness determinations using criteria we have 
established in 40 CFR part 51, appendix V.
    On January 5, 2001, we took final action to find that the State of 
Nevada had failed to make PM-10 nonattainment area SIP submittals 
required for the Las Vegas Valley Planning Area under the CAA. See 66 
FR 1046 (January 5, 2001). That final action, which was effective as of 
December 20, 2000, triggered an 18-month clock for mandatory 
application of sanctions under section 179(a) of the Act and the 
implementing regulations set forth at 40 CFR 52.31. In our final 
action, we indicated that the State may ``turn off'' the sanctions 
clock through the submission of a complete SIP submittal.
    Under section 110(k)(1)(B), if we do not make a completeness 
determination within six months of receipt of a SIP submittal, then the 
submittal shall be deemed complete by operation of law. We had not made 
this determination by January 25, 2002 (i.e., six months from receipt); 
thus, the State's SIP submittal dated July 23, 2001 was deemed complete 
by operation of law effective January 25, 2002.
    However, a SIP submittal that is deemed complete by operation of 
law does not stop a sanctions clock started by a finding by us under 
section 179(a) of the Act. To stop the sanctions clock, we must make an 
affirmative determination that the deficiency forming the basis of the 
finding (in this case, our finding of failure to submit required PM-10 
plan elements) has been corrected. See 40 CFR 52.31(d)(1).
    Therefore, we have reviewed the July 23, 2001 PM-10 submittal from 
the State of Nevada and affirmatively determined that it satisfies our 
completeness criteria set forth for such determinations in appendix V 
of 40 CFR part 51 and that it is thereby complete for the purposes of 
section 110(k)(1) of the Act. Furthermore, the State's submission of 
this complete plan corrects the deficiency forming the basis for our 
finding published in the Federal Register on January 5, 2001. We 
notified the State of our completeness determination by letter to NDEP 
on January 31, 2002, and our letter to NDEP permanently stops the 
sanctions clock as of that date.

B. Adequacy of the Transportation Conformity Budgets

    CAA Section 176(c) requires that federally-funded or approved 
transportation plans, programs, and projects in nonattainment areas 
``conform'' to the area's air quality implementation plans. Conformity 
ensures that federal transportation actions do not worsen an area's air 
quality or interfere with its meeting the air quality standards. We 
have issued a conformity rule that establishes the criteria and 
procedures for determining whether or not transportation plans, 
programs, and projects conform to a SIP. See 40 CFR part 93, subpart A.
    One of the primary tests for conformity is to show transportation 
plans and improvement programs will not cause motor vehicle emissions 
higher than the levels needed to make progress toward and meet the air 
quality standards. The motor vehicle emissions levels needed to make 
progress toward and meet the air quality standards are set in an area's 
attainment and/or RFP plans and are known as the ``emissions budget for 
motor vehicles.'' Emissions budgets are established for specific years 
and specific pollutants. See 40 CFR 93.118(a).
    Before an emissions budget in a submitted SIP revision can be used 
in a conformity determination, we must first determine that it is 
adequate. The criteria by which we determine adequacy of submitted 
emission budgets are outlined in our conformity rule in 40 CFR 
93.118(e)(4). A finding of adequacy does not approve an emissions 
budget, it simply allows States to begin to use the budget in 
conformity determinations pending our action on the overall SIP.
    The Clark County Plan establishes a mobile source emissions budget 
of 201.75 tons per day (tpd) for 2001 and an emissions budget of 141.41 
tpd for 2006. This regional budget is applicable to both the annual and 
24-hour PM-10 standards.
    On November 9, 2001, we notified the State that we find adequate 
for transportation conformity purposes this motor vehicle emissions 
budget. Our adequacy determination was effective on January 28, 2002 
and is documented in section C of the TSD. As a result of our adequacy 
finding, the Regional Transportation Commission (RTC) and the Federal 
Highway Administration (FHWA) are now required to use this budget in 
all conformity analyses.
    As discussed later in this preamble, we are proposing to approve 
both the attainment and reasonable further progress demonstrations for 
the 24-hour standard in the Clark County Plan. An emissions budget was 
set at 155.77 tpd for the 2003 interim year, which is consistent with 
these demonstrations. We, therefore, propose to approve the motor 
vehicle emissions budget for the annual and 24-hour PM-10 standards 
under CAA section 176(c).

C. Adequate Monitoring Network

    We discuss the adequacy of the monitoring network in this preamble 
solely to support our finding that the plan appropriately evaluates the 
PM-10 problem in the Las Vegas area. Reliable ambient data is necessary 
to validate the base year air quality modeling which in turn is 
necessary to assure sound attainment demonstrations.
    The CAA requires states to establish and operate air monitoring 
networks to compile data on ambient air quality for all criteria 
pollutants. CAA section 110(a)(2)(B)(i). Our regulations in 40 CFR part 
58 establish specific regulatory requirements for operating air quality 
surveillance networks to measure ambient concentrations of PM-10, 
including measurement method requirements, network design, quality 
assurance procedures, and in the case of large urban areas, the minimum 
number of monitoring sites designated as National Air Monitoring 
Stations (NAMS).
    Ambient networks, however, do not need to meet all our regulations 
to be found adequate to support air quality modeling. A good spatial 
distribution of sites, correct siting, and quality-assured and quality-
controlled data are the most important factors for air quality 
modeling. Nonattainment area plans developed under title I, part D of 
the Clean Air Act are not, in general, required to address how the 
area's air quality network meets our monitoring regulations. These 
plans are submitted too infrequently to serve as the vehicle for 
assuring that monitoring networks remain current.
    The DAQM operates 17 monitoring sites collecting PM-10 data in the 
Las Vegas area, about half of which are designated as special purpose 
monitors (SPMs) with the remaining monitors designated as NAMS or 
state/local monitoring stations. Table MON-2 in the TSD lists the names 
of the sites and their locations in the Las Vegas area as of July 2000. 
Many of the SPM sites operated by the DAQM are in fact long term sites 
that have been in operation longer than three years. EPA performed a 
technical system audit of the DAQM's ambient air monitoring program in 
August 2001. In this audit, EPA identified some concerns with how DAQM 
characterizes its monitoring networks in terms of site objectives, that 
at least two more NAMS sites are needed, and that the quality assurance 
program needs to be better defined and integrated into the daily 
functions of the air monitoring program. However, we

[[Page 2958]]

do not believe these deficiencies adversely affect our ability to 
determine the air quality status of the area.
    The Las Vegas PM-10 network employs a large number of monitoring 
sites that are spread out over the Las Vegas valley. Given the nature 
of the emission sources, which are mostly local fugitive dust sources, 
and since PM-10 is a localized yet widespread pollutant, we believe a 
dense network such as DAQM operates is appropriate.
    The 24-hour attainment demonstration in the Clark County plan 
relies, in part, on showing attainment at five specific monitoring 
sites. These sites were chosen based on the fact that they represent 
the worst case environments for a mix of PM-10 emission sources: East 
Flamingo site for its high traffic volume; Green Valley for its nearby 
highway construction and race tracks; J.D. Smith for its mixture of 
roadways, small point sources and construction sites; Craig Road for 
its light industrial facility and vacant land influences; and Pittman 
for its larger stationary sources, unpaved parking lots and unpaved 
roads. In 1997-1999 these sites cumulatively recorded 43 exceedences of 
the 24-hour PM-10 standard. They are also representative of similar 
areas in the Las Vegas area that may not have monitoring sites.
    In conclusion, we believe the monitoring network operated by the 
DAQM in 1998 was adequate to support the technical evaluation of the 
PM-10 nonattainment problem for the Clark County Plan. The network 
utilizes EPA reference or equivalent method monitors and the DAQM 
performs routine precision and accuracy checks of the monitoring 
equipment and performs necessary maintenance when warranted.

D. Emissions Inventory

    CAA section 172(c)(3) requires that nonattainment area plans 
include a comprehensive, accurate, and current inventory of actual 
emissions from all sources in the nonattainment area in the designated 
base year and a future attainment year. To meet this requirement, Clark 
County prepared a 1998 base year annual emissions inventory for the 
entire nonattainment area. See Clark County Plan, Chapter 3, Table 3-1. 
Emissions inventories for the baseline and future years for both the 
annual and 24-hour standards are necessary prerequisites to meet 
requirements for BACM and demonstration of attainment per CAA section 
189(b). In the Las Vegas Valley, both regional and microscale modeling 
inventories are needed to accurately reflect the sources that are 
contributing to ambient levels of the 24-hour PM-10 standard. By design 
and need, the microscale inventory includes only sources within a small 
area around a monitor rather than all sources within the entire 
nonattainment area.
    For the attainment demonstration, the Clark County Plan relies upon 
regional annual and 24-hour emissions inventories associated with a 
portion of the entire PM-10 nonattainment area titled the ``BLM 
Disposal Area''. See Clark County Plan, Chapter 3, section 3.3 and 
Appendix E. All lands controlled by the federal government outside the 
BLM disposal area are to remain in their native state and the boundary 
can only be changed by an act of the United States Congress. 
Approximately 99 percent of the nonattainment area resides within the 
BLM Disposal Area and nearly all anthropogenic sources within the 
nonattainment area occur within the BLM Disposal Area, making it the 
appropriate focus for the attainment demonstration. We address the 
modeling used in the attainment demonstration later in this notice. The 
rules adopted by Clark County to address sources within the BLM 
Disposal Area equally apply to the entire PM-10 nonattainment area.
    The Plan contains two 1998 BLM Disposal Area emissions inventories 
for the annual standard: a valley-wide inventory and a microscale 
inventory for the area surrounding the J.D. Smith monitoring station, 
which was the only site that measured a violation of the annual NAAQS. 
For the 24-hour standard, the Plan contains a base year emissions 
inventory for the design day (December 21, 1998), which is scaled from 
the annual valley-wide inventory with additional wind erosion emissions 
factored in due to specific meteorological conditions.
    Clark County also prepared future year PM-10 inventories comparing 
an ``uncontrolled'' scenario to a scenario assuming application of 
control measures adopted by Clark County as BACM. The Plan contains 
uncontrolled 2001 and 2006 annual valley-wide emissions inventories and 
a 2006 uncontrolled valley-wide 24-hour inventory. Emissions 
inventories were also developed for each of the five microscale sites. 
These microscale inventories are specialized modeling inventories and 
are not intended to satisfy the CAA section 172(c)(3) requirement.\10\
---------------------------------------------------------------------------

    \10\ The microscale inventories include only sources within a 
small area surrounding each monitor rather than all sources within 
the entire nonattainment area, the requirement in CAA section 
172(c)(3).
---------------------------------------------------------------------------

    The following fugitive dust source categories make up 97 percent 
and 99 percent of PM-10 emissions in the base year annual valley-wide 
and 24-hour BLM Disposal Area inventories for the Las Vegas Valley, 
respectively: vacant land, construction, paved roads and unpaved roads. 
The inventory includes only primary PM-10 as chemical mass balance 
receptor modeling showed that secondary and condensable particulate 
formation contribute less than significant amounts to ambient PM-10 
concentrations. Clark County Plan, Chapter 4, section 4.2.1.
    In our review of the Plan, we found that the emissions estimates 
for all of the source categories are based on emissions factors and 
methodologies recommended by EPA, or are derived from a specific study 
or data collected from a source category in the area (e.g., vacant 
lots). We propose to find that the inventory projections methodologies 
and calculations rely upon reasonable assumptions and provide a 
sufficient basis upon which to assess control measure impacts on future 
PM-10 air quality in the Las Vegas area. Clark County has also included 
commitments in the Plan to improve and update the emissions inventories 
in future years.

E. Contribution of PM-10 Exceedences of Major Sources of PM-10 
Precursors

    CAA section 189(e) requires BACT to be applied to major stationary 
sources of PM-10 precursors if these sources contribute significantly 
to PM-10 exceedences in the area. Clark County determined that 
stationary sources, including sand and gravel operations, natural gas-
fired utility power plants, asphalt concrete plants, industrial 
processes, and other sources cumulatively contribute less than 1 [mu]g/
m\3\ of the design day concentration, placing them below the 5 [mu]g/
m\3\ significance threshold for the 24-hour standard. Design day micro-
inventory concentrations from stationary source emissions were higher 
in some cases (3.74 [mu]g/m\3\ and 3.53 [mu]g/m\3\ at the Pittman and 
Craig Road monitoring sites, respectively), but were still below the 
threshold of presumed significance for this source category. Therefore, 
BACT is not required to be applied to stationary sources per CAA 
section 189(e).

F. Implementation of Best Available Control Measures

    CAA section 189(b)(1)(B) requires that a serious area PM-10 plan 
provide for the implementation of BACM within four years of 
reclassification to serious. Under our applicable guidance, BACM must 
be applied to each significant area-

[[Page 2959]]

wide source category. Addendum at 42011. As discussed in section III of 
this preamble, we have established a four-step process for evaluating 
BACM in serious area PM-10 plans.
Steps 1 and 2: Determination of Significant Sources
    The first step in the BACM analysis is to develop a detailed 
emissions inventory of PM-10 sources and source categories that can be 
used in modeling to determine their impact on ambient air quality. 
Addendum at 42012. The second step is to use this inventory in air 
quality modeling to evaluate the impact on PM-10 concentrations over 
the standards of the various sources and source categories to determine 
which are significant.
    The development of the detailed emissions inventory is discussed in 
the preceding section and in the TSD. We propose to find that the 
baseline emissions inventory contains a sufficient level of detail to 
enable appropriate evaluation of the Plan's control measures for BACM 
purposes. The determination of source significance is based primarily 
on the J.D. Smith annual inventory and the 24-hour micro-inventories at 
the five representative sites, supplemented by reviews of the 1998 
valley-wide 24-hour emissions inventory, the 1998 valley-wide annual 
emissions inventory, and Chemical Mass Balance modeling. Clark County 
Plan, Chapter 4, pg. 4-1.
    From these evaluations, the Clark County Plan identifies the 
following sources as significant with respect to the annual standard:
1. Disturbed vacant land/unpaved parking lots
2. Construction (including highway construction)
3. Paved roads
4. Unpaved roads

    The same source categories are deemed significant for the 24-hour 
standard, with the additional category of:

5. Race tracks
    Clark County determined that the following source categories are 
not significant for both standards:

1. Stationary point sources (sand and gravel operations, utilities--
natural gas, asphalt concrete manufacture, industrial processes, other)
2. Some stationary area sources (small point sources, fuel combustion 
sources, residential wood combustion, open burning, farming operations)
3. Nonroad mobile sources (airport support equipment, commercial 
equipment, construction and mining equipment, lawn and garden 
equipment, railroad equipment, airport emissions)
4. Onroad mobile vehicle exhaust and other emissions
5. Secondary aerosol particulate
    Emissions from the proposed de minimis categories are a small 
percentage (3% collectively) of the total 1998 BLM Disposal Area annual 
and 24-hour PM-10 emissions inventories. The minimal contribution of 
the proposed de minimis source categories to the inventory supports 
that, both individually and collectively, they have a minor impact on 
elevated annual and 24-hour PM-10 levels in the Clark County 
nonattainment area.
    For the 24-hour standard, the Clark County Plan demonstrates that 
its selection of significant source categories is appropriate by 
showing that controls on the de minimis source categories would not 
result in attainment of the 24-hour standard by 2001. See Clark County 
Plan, Chapter 7, section 7.4.
    We propose to find that the Clark County Plan has not excluded any 
source categories that should be considered significant from its list 
of significant source categories. The Plan presents acceptable modeling 
to evaluate the impact of various PM-10 sources and source categories 
on PM-10 levels and to derive a comprehensive list of significant 
source categories.
Step 3: Identification of Potential BACM
    In preparing the list of candidate BACM, Clark County reviewed our 
guidance documents on BACM, other EPA documents on PM-10 control, as 
well as PM-10 plans from other serious PM-10 areas in the United 
States. Clark County also evaluated controls proposed during public 
comment.
    The Clark County plan appropriately screened the list of candidate 
BACM to eliminate measures that did not apply to significant source 
categories in the area, or were technologically infeasible for the area 
because they would not reduce PM-10 emissions. The Clark County Plan 
also provides cost-effectiveness estimates for each of the candidate 
BACM.
    We propose to find that the Clark County Plan identified and 
evaluated potential BACM for the Las Vegas area consistent with our 
guidance. As we will discuss below in our evaluations of the 
implementation of BACM for each significant source category, we do not 
believe that the Clark County plan left out any candidate BACM.
Step 4: Implementation of RACM \11\ and BACM and Inclusion of MSM for 
Each Significant Source Category
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    \11\ Because the RACM demonstration is subsumed in the BACM 
demonstration, a separate analysis to determine if the measures 
represent a RACM level of control is not necessary. Our proposed 
approval of the Clark County Plan's provisions relating to the 
implementation of BACM is also a finding that the plan provides for 
the implementation of RACM.
---------------------------------------------------------------------------

    In the following sections, we review the results of the Clark 
County Plan's BACM analysis and adopted measures. The same control 
measures apply to BACM determinations for both the annual and 24-hour 
PM-10 standards. We also present our evaluation of the Plan's 
provisions for including MSM alongside our evaluation of BACM 
implementation for each significant source category.
    Clark County adopted sections 90 through 94 and section 0 on 
November 16, 2000. Sections 90 through 93 were subsequently revised by 
the DAQM on November 20, 2001. Clark County submitted these revised 
rules to EPA on October 24, 2002 for our action in place of the 
sections 90 through 93 adopted on November 16, 2000. These rules 
address the significant sources identified in the Plan, along with SIP 
commitments for unpaved roads and unpaved road shoulders contained in 
Chapter 4 of the Plan.
    Clark County has also committed to increase its staffing levels to 
enhance compliance and enforcement of these rules to assure that the 
emission reductions necessary for expeditious attainment are achieved. 
This commitment is an important component of our proposed finding that 
the Clark County Plan provides for implementation of BACM and inclusion 
of MSM.
    We also have evaluated the rules for enforceability and consistency 
with applicable CAA requirements for SIP revisions in section 110 and 
Part D and EPA rulemaking policy.
a. Disturbed Vacant Land
    This category includes windblown fugitive dust emissions from 
disturbed surfaces of vacant land. On vacant land, fugitive dust 
emissions are caused by virtually any activity which disturbs an 
otherwise naturally stable parcel of land, including earth-moving 
activities, material dumping, weed abatement, and vehicle traffic. Wind 
erosion from disturbed vacant land accounts for 45 percent of total PM-
10 emissions in the 1998 24-hour BLM Disposal Area inventory and 39 
percent of total PM-10 emissions in the 1998 annual BLM Disposal Area 
valley-wide inventory,

[[Page 2960]]

making it the largest source of PM-10 in the Las Vegas area.
    The suggested measures for controlling emissions from disturbed 
vacant land fall into one of two categories: preventing motor vehicle 
disturbance of vacant land, and stabilizing vacant land.\12\ We propose 
to find that the Clark County Plan evaluates a comprehensive set of 
potential controls for disturbed vacant land including the potential 
MSM from other States.
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    \12\ Constructing windbreaks was also identified but deemed less 
stringent than surface stabilization. Therefore, the benefits of 
applying this potential BACM are subsumed in the more stringent 
emission reductions associated with surface stabilization. In 
addition, Clark County identified weed abatement on vacant land as a 
separate category. Since this pertains to ``surface stabilization'' 
we include it under that category; however, weed abatement by 
discing and blading also generates emissions as the activity is 
being conducted, therefore, Clark County has adopted separate 
requirements for weed abatement in its vacant lot rule.
---------------------------------------------------------------------------

    Clark County implemented both access prevention and surface 
stabilization with specific requirements in section 90 ``Fugitive Dust 
From Open Areas and Vacant Lots''. Section 90 requires prevention of 
motor vehicles (including off-road vehicles), where there is evidence 
of such use, on open areas and vacant lots greater than or equal to 
5,000 square feet by installation of barriers or other effective 
traffic control measures and stabilization of motor-vehicle disturbed 
surfaces on such lots. Also, where 5,000 square feet or more of 
cumulative disturbed surface exists (from any activity) all disturbed 
areas must be stabilized using water, dust palliatives or gravel. When 
discing or blading areas of 5,000 square feet or more, water must be 
applied before and during operations and the disturbed surface 
stabilized afterwards.
    The requirements apply to public and private vacant land alike. 
Clark County determined that less than one percent of vacant land 
within the BLM Disposal Boundary \13\ consists of parcels smaller than 
5,000 square feet, thus the requirements provide a stringent threshold 
of applicability. Section 90 contains appropriate performance standards 
and test methods for surface stability,\14\ recordkeeping requirements, 
and otherwise meets EPA's enforceability criteria.
---------------------------------------------------------------------------

    \13\ We note that section 90 requirements apply throughout the 
entire PM-10 nonattainment area.
    \14\ Standards include a visible crust determination, 20% cover 
of nonerodible elements, or a threshold friction velocity (corrected 
for nonerodible elements) of 100 cm/sec or higher.
---------------------------------------------------------------------------

    Clark County has also made a SIP commitment to adopt a requirement 
for dust management plans on large tracts (i.e., 10,000 acres or more) 
of government owned land.\15\
---------------------------------------------------------------------------

    \15\ Clark County submitted a SIP amendment that establishes a 
revised deadline of March 31, 2003 for the section 90 and other rule 
revisions.
---------------------------------------------------------------------------

    Section 90 vacant lot requirements became effective on January 1, 
2001. We propose to find that the Clark County Plan provides for the 
implementation of vacant lot measures as expeditiously as practicable, 
consistent with our proposed MSM policy.
    For the MSM analysis, Clark County demonstrated that the section 90 
requirements are of equivalent or greater stringency than those adopted 
or in practice in other areas.
    We, therefore, propose to find that the Clark County Plan provides 
for the implementation of BACM and for the inclusion of MSM for 
disturbed vacant land. We also propose approval of section 90 into the 
SIP in accordance with CAA section 110 and the requirements of CAA 
Title I, part D.
b. Unpaved Parking Lots
    This category includes emissions from re-entrained road dust from 
vehicle traffic on unpaved parking lots and windblown dust entrained 
from the disturbed surface of unpaved parking lots. Windblown emissions 
from unpaved parking lots are included in the disturbed vacant land 
category in the 1998 base year valley-wide and BLM Disposal Area 
emissions inventories. The extent of unpaved parking lots affected by 
the controls in adopted Rule 92 has not been determined (or credited) 
on a valley-wide inventory basis,\16\ but instead only with respect to 
the microscale inventories.
---------------------------------------------------------------------------

    \16\ See Clark County Plan, Chapter 4, subsection 4.5.2.2.5.
---------------------------------------------------------------------------

    There are two principal ways to control emissions from unpaved 
parking lots, both of which Clark County identified: prohibit unpaved 
parking lots or stabilize existing lots. We propose to find that the 
Clark County Plan evaluates a comprehensive set of potential controls 
for unpaved parking lots including the potential MSM from other States.
    Clark County adopted requirements to stabilize existing unpaved 
parking lots in section 92 ``Fugitive Dust From Unpaved Parking Lots.'' 
Clark County also adopted a SIP commitment to modify section 92 to 
prohibit new unpaved parking lots with limited exceptions.\17\ 
Therefore, both potential BACM have or will shortly be adopted.\18\
---------------------------------------------------------------------------

    \17\ Clark County submitted a SIP amendment that establishes a 
revised deadline of March 31, 2003 for the section 92 and other rule 
revisions.
    \18\ Adoption of a requirement prohibiting new unpaved parking 
lots, in addition to the section 92 stabilization requirements, 
collectively fulfill BACM and MSM. However, since the section 92 
surface stabilization requirements apply to both new and existing 
unpaved parking lots, the requirement that new lots be paved 
provides only incremental emission reductions beyond measures 
already adopted and, therefore, is not critical in our determination 
that measures for this source category have been adopted as 
expeditiously as practicable.
---------------------------------------------------------------------------

    Section 92 requires that all unpaved parking lots greater than or 
equal to 5,000 square feet be stabilized by application of paving, dust 
palliatives, or a combination of dust palliatives in the travel lanes 
and two inches of gravel. Lots used intermittently (thirty-five days 
per year or less), must be stabilized according to section 92 standards 
only on days of use. On days of inactivity, however, such lots are 
subject to section 90 standards.
    The section 92 requirements apply to both public and private 
unpaved parking lots. The analysis Clark County used to assess the 
percentage of vacant land parcels smaller than 5,000 square feet in the 
BLM Disposal Area applies to unpaved parking lots as well. Section 92 
contains appropriate performance standards and test methods for surface 
stability and opacity,\19\ recordkeeping requirements, and otherwise 
meets EPA's enforceability criteria.
---------------------------------------------------------------------------

    \19\ Both a 20% opacity standard according to a modified EPA 
Reference Method 9 and a silt content standard of 8% or 
alternatively, a silt loading standard of 0.33 oz/sq. ft., apply.
---------------------------------------------------------------------------

    Section 92 unpaved parking lot requirements became effective on 
January 1, 2001. We propose to find that the Clark County Plan provides 
for the implementation of unpaved parking lot measures as expeditiously 
as practicable, consistent with our proposed MSM policy.
    For the MSM analysis, Clark County demonstrated that the section 92 
requirements are more stringent than those adopted or in practice in 
other areas. We, therefore, propose to find that the Clark County Plan 
provides for the implementation of BACM and for the inclusion of MSM 
for unpaved parking lots. We also propose SIP approval of section 92 
per CAA section 110 and Part D.
c. Construction Sites
    Sources of fugitive dust emissions at construction sites include 
land clearing, earthmoving, excavating, construction, demolition, 
material handling, bulk material storage and/or transporting 
operations, material track out or spillage onto paved roads (which we 
have addressed in the paved road section), and vehicle use and movement 
on site (e.g., the operation of any equipment on unpaved surfaces, 
unpaved roads and

[[Page 2961]]

unpaved parking areas). Windblown emissions from disturbed areas and 
inactive storage piles on construction sites are also a source of PM-
10. Construction operations, which are mostly earthmoving, represent 
approximately 37 percent of the 24-hour BLM Disposal Area emissions 
(not including trackout emissions).
    The suggested measures in the Clark County Plan for controlling 
emissions from constructions sites include a detailed list of controls 
encompassing a great variety of dust-generating activities, performance 
standards, enforcement-related measures,\20\ and new measures not 
implemented in other areas. The measures considered include all sources 
of active dust generation and windblown dust on construction sites. We 
propose to find that the Clark County Plan evaluates a comprehensive 
set of potential controls for construction sites emissions including 
the potential MSM from other States.
---------------------------------------------------------------------------

    \20\ We do not consider improved enforcement a BACM but rather a 
method of implementing BACM.
---------------------------------------------------------------------------

    Clark County adopted requirements pertaining to construction sites 
in Section 94 ``Permitting and Dust Control for Construction 
Activities'' on November 16, 2000. As part of this action, Clark County 
also adopted a ``Section 94 Handbook,'' along with relevant tables of 
contents, definitions, articles, tables, indexes, examples and 
appendices.\21\ Together these documents make up the required control 
measures applicable to construction sites. Section 94 establishes the 
basic requirements for construction site dust control permits and other 
standards while the Section 94 Handbook lays forth more specific 
requirements for each dust-generating source.
---------------------------------------------------------------------------

    \21\ The Section 94 Handbook and associated documents are 
explicitly adopted as part of section 94 per subsection 94.3.1 of 
the rule.
---------------------------------------------------------------------------

    Dust control permits are required prior to soil disturbance for all 
sites greater than \1/4\ acre, mechanized trenching greater than 100 
feet in length, and mechanical demolition of structures greater than 
1,000 square feet. However, all sites with construction activities 
regardless of size are subject to the requirements of section 94 and 
the Section 94 Handbook. Dust control permits must contain a ``Dust 
Mitigation Plan'' that employs the Section 94 Handbook Best Management 
Practices (BMPs). The Section 94 Handbook requirements are not only 
activity-specific and designed to be placed into dust control permits 
in a phase-specific manner, but are also specific to the type of soil 
at a particular site or location and the soil's potential to emit 
fugitive dust. Therefore, each Dust Mitigation Plan must incorporate 
the appropriate BMPs per the Section 94 Handbook according to soil type 
parameters.\22\ Sites 10 acres or greater must provide a more detailed 
project description and site plan according to a ``Site Specific Dust 
Mitigation Plan''.
---------------------------------------------------------------------------

    \22\ Five soil type categories are included that take into 
account both silt content and optimum moisture content: high, 
moderately high, moderately low, low and slight. The high and 
moderately high soils generally require that a surfactant mixture 
with water or tackifyer mixture with water, respectively, be applied 
for effective dust control.
---------------------------------------------------------------------------

    The Section 94 Handbook establishes a specific performance standard 
(i.e., Control Requirement) that must be met for each identified 
construction activity.\23\ Multiple Control Requirements apply for each 
construction activity. A menu of control measure options is provided, 
one or more of which must be specifically identified in the Dust 
Mitigation Plan to meet each applicable Control Requirement for the 
activity. The control measures identified in the Dust Mitigation Plan 
are subject to review and approval by the DAQM as part of the dust 
control permit.
---------------------------------------------------------------------------

    \23\ Construction activities with specific BMPs include 
trenching, truck loading, screening, landscaping, paving/subgrade 
preparation, disturbed inactive surfaces, track out control, 
staging, equipment, and material storage areas, construction 
traffic, crushing, abrasive blasting, soil and rock blasting, 
stockpiles, importing bulk materials, backfilling, clearing and 
grubbing, clearing forms, cut and fill and demolition.
---------------------------------------------------------------------------

    Specific requirements include a 20 percent opacity standard for 
active earthmoving operations and construction traffic. Also, all 
construction activities are prohibited from creating a visible plume 
that extends more than 100 yards from the point of origin. Construction 
site trackout is addressed by both a requirement to install and 
maintain trackout control devices at all traffic access/exit points and 
a requirement that trackout be cleaned up immediately (within one hour 
of discovery) if it extends a cumulative distance of 50 feet or more. 
In addition, all trackout must be cleaned up by the end of the work day 
or evening shift. To prevent emissions during bulk material transport 
and handling, truck loads must be covered on public roads and a 20 
percent opacity limit applies during truck loading and unloading. Truck 
loads of bulk materials on site must either be covered, maintain three 
to six inches of freeboard, or maintain optimum moisture content of 
soils. All inactive disturbed soil areas must meet surface 
stabilization standards, including stockpiles and parking areas.\24\ 
Unpaved haul roads must comply with both a 20% opacity standard \25\ 
and a surface stabilization standard.\26\ In high wind conditions, 
owners/operators must cease all construction activities if fugitive 
dust exceeds 20 percent opacity but must continue operation of water 
trucks and pulls except under specific circumstances. Sites with 
greater than 50 acres of actively disturbed soil are required to employ 
a responsible person to monitor dust control at the site.\27\
---------------------------------------------------------------------------

    \24\ Surfaces must comply with a visible crust standard per the 
test method in section 94 but may also comply with other surface 
stability standards in section 90.
    \25\ A modified EPA Reference Method 9 applies, found in section 
91.
    \26\ A 6 percent silt content and/or 0.33 oz per square foot 
silt loading standard applies.
    \27\ This requirement was newly developed by Clark County and 
serves the dual purpose of improving compliance of larger sites by 
active monitoring of dust control-related efforts, but also 
encourages owners/operators to keep the total amount of disturbed 
surface under 50 acres as a preventative measure.
---------------------------------------------------------------------------

    Section 94 and the Section 94 Handbook and other documents adopted 
by reference contain appropriate performance standards and test methods 
for opacity and surface stability, recordkeeping requirements, and 
otherwise meet EPA's enforceability criteria. Although the opacity 
standard per the test method included in section 94 is the best 
currently available to assess the opacity of emissions from the variety 
of construction activities generating fugitive dust, it may not be 
sufficient in all field circumstances to control intermittently-
occurring dust plumes to BACM levels. Therefore, Clark County has 
adopted a SIP commitment to fund additional research to develop an 
acceptable alternative test method and revise section 94 accordingly. 
See Chapter 4 of the Plan, section 4.8.2.7. We consider this commitment 
as factoring into our determination that the Plan provides for BACM/
MSM.
    Section 94 construction site requirements became effective on 
January 1, 2001. We propose to find that the Clark County Plan provides 
for the implementation of construction site measures as expeditiously 
as practicable, consistent with our proposed MSM policy.
    For the MSM analysis, Clark County demonstrated that the section 94 
and section 94 Handbook requirements are of equivalent or greater 
stringency than those adopted or in practice in other areas.
    We, therefore, propose to find that the Clark County Plan provides 
for the

[[Page 2962]]

implementation BACM and for the inclusion of MSM for construction 
sites. We also propose SIP approval of section 94 and the section 94 
Handbook and referenced documents per CAA section 110 and part D.
d. Paved Road Dust
    Paved road dust is fugitive dust that is deposited on a paved 
roadway and then re-entrained into the air by the action of tires 
grinding on the roadway. Dust can be deposited on the roadway from 
being blown onto the road from disturbed areas, tracked onto the road 
from unpaved shoulders, unpaved roads, or other unpaved access points, 
stirred up from unpaved shoulders by wind currents created from traffic 
movement, spilled onto the road by haul trucks, and carried onto the 
road by water runoff or erosion. Paved road dust constitutes 26 percent 
of the 1998 valley-wide annual BLM Disposal Area emissions, thus is the 
second largest source of valley-wide PM-10 in the Las Vegas area. Paved 
road dust accounts for 13 percent of the overall 24-hour BLM Disposal 
Area 1998 inventory.
    The suggested measures for controlling emissions from paved road 
dust fall into two categories: Preventing deposition of material onto a 
roadway, and cleaning material off the roadway.\28\ The Clark County 
Plan includes ten potential BACM for paved road dust that fall under 
one of these two categories. We believe this list is complete and 
propose to find that the Clark County Plan evaluates a comprehensive 
set of potential controls for paved road dust including the potential 
MSM from other States.
---------------------------------------------------------------------------

    \28\ Reductions in vehicle miles traveled and vehicle trips are 
also candidate transportation control measures (TCMs) that could 
have positive impacts on reducing paved road dust. However, these 
measures are more appropriate for areas addressing significant on-
road mobile source emissions and would not impact paved road dust on 
the same magnitude as measures directed towards preventing or 
removing deposition. TCMs are separately addressed and included in 
Clark County's Carbon Monoxide Plan, adopted on August 1, 2000.
---------------------------------------------------------------------------

    Clark County adopted requirements for paved road shoulders and PM-
10 efficient street sweeping requirements in section 93 ``Fugitive Dust 
from Paved Roads and Street Sweeping Equipment''. Clark County adopted 
SIP commitments to stabilize existing unpaved road shoulders and 
require use of vacuum crack seal equipment. See Clark County Plan, 
Chapter 4, sections 4.8.3.2 and 4.8.2.9.\29\ Measures to prevent 
construction site trackout onto paved roads from truck tires and 
material transport are included in section 94 and the section 94 
Handbook (construction activity regulations). For other measures \30\, 
Clark County provided documentation of ongoing programs in place.\31\
---------------------------------------------------------------------------

    \29\ Clark County submitted a SIP amendment that establishes a 
revised deadline of March 31, 2003 for the section 93 and other rule 
revisions.
    \30\ Prevention of storm water drainage deposits, cleanup of 
material spills and erosion-caused deposits, and routine sweeping of 
paved roads.
    \31\ See Clark County Plan, Appendix J and Chapter 4, pg. 4-69.
---------------------------------------------------------------------------

    The paved road measures relied upon for emissions reductions 
towards demonstrating attainment include stabilizing unpaved road 
shoulders, preventing trackout from construction sites, and reducing 
deposition from other fugitive dust sources subject to control per 
sections 90 through 94. The remaining measures are either already 
factored into the baseline or are not credited with emissions 
reductions towards the attainment demonstration.\32\
---------------------------------------------------------------------------

    \32\ For example, a large portion of the publicly-owned street 
sweeping fleet already consisted of PM-10 efficient street sweepers 
in 1998 and routine sweeping programs were already in place.
---------------------------------------------------------------------------

    Section 93 requires owners/operators using street sweeping 
equipment or services on paved roads or parking lots to acquire or 
contract to acquire only certified PM-10 efficient street sweeping 
equipment \33\ after January 1, 2001. We note this requirement applies 
to both private operators and government agencies.
---------------------------------------------------------------------------

    \33\ This refers to a street sweeper which has been certified by 
the South Coast Air Quality Management District (SCAQMD) to comply 
with the performance standards in SCAQMD's Rule 1186 according to 
test methods specified in Rule 1186.
---------------------------------------------------------------------------

    For new or modified road shoulders, section 93 requires four feet 
of paved or stabilized shoulder on each side of the paved travel 
section or construction of curbing adjacent to the paved travel 
lane.\34\ Medians must also be stabilized.
---------------------------------------------------------------------------

    \34\ Clark County has made a SIP commitment to strengthen this 
provision to provide for eight feet of stabilized shoulder adjacent 
to the paved travel section on roads with 3,000 vehicles per day or 
more. The new SIP commitment date of March 31, 2003 applies per 
Clark County's SIP amendment.
---------------------------------------------------------------------------

    For existing unpaved road shoulders, section 93 requires 
stabilization within 365 days following initial discovery that the road 
fails to meet the stabilization standards and other requirements that 
apply to new/modified paved road shoulders. The stringency of this 
provision is necessarily enhanced by the SIP commitment in the Plan 
which lays forth the program and definitive dates by which all 
unstabilized shoulders will be identified and stabilized by public 
agencies in the Valley. Clark County indicates that shoulder 
improvements will be prioritized by each entity for their respective 
jurisdictions based upon emissions estimates. To implement the program, 
Plans will be completed by February 15, 2002, and at a minimum, funds 
will be obligated to improve 33 miles of paved road shoulders by the 
end of 2003, with all shoulders to be stabilized by the end of 2006. 
Annual updates on the progress of stabilizing shoulders will be 
submitted to Clark County and EPA. In a June 28, 2002 letter, the DAQM 
indicates that the respective public entities have submitted initial 
plans for stabilizing shoulders and initiated programs to begin 
stabilization.
    Section 93, paved road requirements, became effective on January 1, 
2001. The SIP commitment by governmental entities to stabilize 33 miles 
of unpaved shoulders by the end of 2003 and all shoulders by the end of 
2006 allows time for public works agencies to complete an inventory of 
the unpaved shoulders in their respective jurisdictions and adopt 
schedules under capital improvement programs to stabilize shoulders 
each year using Congestion Management Air Quality (CMAQ) funds. Other 
measures have on-going implementation schedules because they are part 
of an on-going capital improvement program, e.g., storm water drainage 
projects. Therefore, we propose to find that the Clark County Plan 
provides for the implementation of paved road measures as expeditiously 
as practicable, consistent with our proposed MSM policy.
    For the MSM analysis, Clark County demonstrated that the section 93 
requirements and SIP commitments contained in the Plan are of 
equivalent or greater stringency than those adopted or in practice in 
other areas.
    We, therefore, propose to find that the Clark County Plan provides 
for the implementation of BACM and for the inclusion of MSM for paved 
road dust.
e. Unpaved Roads
    This category includes re-entrained dust from vehicle travel on 
unpaved roads and windblown emissions from unpaved roads. There are 
three categories of unpaved roads in the Clark County nonattainment 
area: Publicly-owned/maintained roads, privately-owned roads, and 
unpaved haul/access roads associated with construction sites or 
industrial facilities. We have addressed the latter category in the 
discussion of construction site measures (section IV.D.3.c) of this 
document.
    There are three ways to control fugitive dust emissions from 
unpaved roads: surface treatment to reduce dust from unpaved roads and 
alleys, traffic reduction/speed control plans for unpaved roads, and 
prohibition of

[[Page 2963]]

unpaved haul roads. All three are identified and evaluated in the Clark 
County Plan. We believe this list is complete and propose to find that 
the Clark County Plan evaluates a comprehensive set of potential BACM 
and MSM for unpaved roads.
    Clark County did not implement traffic reduction/speed control on 
public and private roads in the Valley.\35\ This is because the County 
determined that reducing traffic on public and private unpaved roads is 
not as stringent a measure as paving or other means of surface 
stabilization. Speed control is difficult to enforce compared to road 
paving, which can be readily verified and results in greater emissions 
reductions. Thus, the benefits of applying this potential BACM are 
subsumed in the more stringent emission reductions associated with 
surface stabilization.
---------------------------------------------------------------------------

    \35\ However, traffic reduction/speed control is included in the 
Section 94 Handbook as a BMP for unpaved haul/access construction 
site roads.
---------------------------------------------------------------------------

    Clark County adopted requirements to stabilize existing unpaved 
roads and alleys and to prohibit new unpaved roads in public 
thoroughfares in section 91 ``Fugitive Dust From Unpaved Roads, Unpaved 
Alleys and Unpaved Easement Roads.'' Also, Clark County adopted a SIP 
commitment for County and City Public Works agencies to pave unpaved 
roads subject to section 91.\36\
---------------------------------------------------------------------------

    \36\ See Chapter 4, section 4.8.3.1 of the Plan.
---------------------------------------------------------------------------

    Section 91 requires all existing unpaved roads that receive 150 
vehicle trips per day or more to be paved or treated with dust 
palliatives on the following schedule: \1/3\ of the total by June 2001, 
two-thirds of the total by June 2002, and any remaining roads by June 
1, 2003. Section 91 prohibits construction of new unpaved roads or 
alleys in public thoroughfares after June 22, 2000 unless the unpaved 
road is an interim component of an active paving project.
    Section 91 requirements apply to both public and private roads. 
Clark County estimates that approximately 64 miles of the 259-mile 
total base year inventory of publicly-owned and maintained unpaved 
roads have 150 or more average daily vehicle trips (ADT). The unpaved 
roads inventory was developed by the respective Public Works 
departments after extensive review of the existing road network. Given 
that higher ADT unpaved roads proportionately contribute greater 
emissions than lower ADT roads, the 64 miles constitute 66% of 
emissions from the total inventoried road network. The SIP commitment 
for unpaved roads made by County and City Public Works agencies not 
only goes beyond the section 93 requirements in that it ensures roads 
will receive the maximum emissions reductions possible through paving, 
but further enhances coverage in that the City of Las Vegas makes an 
additional commitment to pave all unpaved roads within its jurisdiction 
by the end of 2006. We also note that the SIP commitment concerning 
paved road shoulders \37\ indicates that shoulder improvements and road 
paving for unpaved roads with less than 150 ADT will be prioritized by 
each entity for their respective jurisdictions based upon emissions 
estimates. Thus, road paving efforts by jurisdictions may very well go 
beyond the requirements in section 91 depending on the availability of 
CMAQ dollars. Section 91 contains specific reporting requirements for 
the responsible jurisdictions and the SIP commitment for unpaved roads 
provides for annual progress updates to be provided to the DAQM and 
EPA.
---------------------------------------------------------------------------

    \37\ See Chapter 4, section 4.8.3.2 of the Plan.
---------------------------------------------------------------------------

    While the miles of privately owned unpaved roads have not been 
fully inventoried in detail, a total of 45 miles of private roads were 
identified by various municipalities and the County, none of which were 
determined to have traffic volumes greater than 50 ADT. Clark County 
included a SIP commitment in the Plan to develop an improved inventory 
of both public and private unpaved roads.\38\
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    \38\ See Chapter 4, section 4.8.2.3 of the Plan.
---------------------------------------------------------------------------

    Section 91 also contains requirements that address the prospect of 
vehicle traffic increases on unpaved roads that are currently below the 
150 ADT threshold but in the future exceed it. Any existing unpaved 
roads which equal or exceed 150 ADT after June 1, 2003 are subject to 
control according to section 91 within 365 calendar days following 
initial discovery that vehicular traffic equals or exceeds 150.
    Section 91 contains appropriate performance standards and test 
methods for surface stability and opacity,\39\ recordkeeping 
requirements, and otherwise meets EPA's enforceability criteria.
    Section 91 unpaved road requirements prohibit new unpaved roads as 
of June 22, 2000. Clark County indicates that the CMAQ funding 
obligated by the responsible government agencies (totaling over $25 
million) will support completing approximately one-third of the total 
paving requirement in section 91 for each year from 2001 to 2003.\40\ 
Moreover, we note in a June 28, 2002 letter from the DAQM that the 
responsible jurisdictions have exceeded the section 91 required one-
third increment of road paving by June 2001 and have reported paving 86 
percent, or a total of 55 of the 64-mile public road inventory 
receiving 150 ADT or more. This demonstrates the commitment of Clark 
County governmental entities to implement control measures 
expeditiously. We propose to find that the Clark County Plan provides 
for the implementation of unpaved road measures as expeditiously as 
practicable, consistent with our proposed MSM policy.
---------------------------------------------------------------------------

    \39\ Where paving is not conducted (this would only apply to 
roads that are not included in the SIP commitment by Public Works 
entities), both a 20% opacity standard according to a modified EPA 
Reference Method 9 and a silt content standard of 6% or 
alternatively, a silt loading standard of 0.33 oz/sq. ft., apply.
    \40\ See Chapter 7, pg. 7-4 of the Plan.
---------------------------------------------------------------------------

    For the MSM analysis, Clark County demonstrated that the section 91 
requirements and SIP commitments for unpaved roads are equally or more 
stringent than those adopted or in practice in other areas.
    We, therefore, propose to find that the Clark County Plan provides 
for the implementation of BACM and for the inclusion of MSM for unpaved 
roads. We also propose SIP approval of section 91 per CAA section 110 
and part D.
f. Race Tracks
    Race track emissions are both actively generated from use by 
offroad vehicles, e.g., dirt bikes and all-terrain vehicles (ATVs), and 
windblown from disturbed surfaces following use. Clark County 
determined that race track emissions are only significant with respect 
to the 24-hour standard. Race track emissions that were found to have 
significant impacts at two micro-inventory sites were associated with 
unauthorized ATV use on a vacant parcel.\41\
---------------------------------------------------------------------------

    \41\ See Chapter 4, pg. 4-81 of the Plan.
---------------------------------------------------------------------------

    Clark County did not prepare a separate BACM analysis for race 
tracks. Rather, Clark County implements its strategy for race tracks 
through section 90 controls for disturbed vacant land and open areas. 
We note that there are three potential BACM for control of dirt race 
tracks: Prohibit race tracks, treat the surface of race tracks with 
dust suppressants or palliatives, and establish wind breaks around the 
circumference of tracks. Of these potential BACM, Section 90 controls 
address the first two. Establishing wind breaks has not been adopted, 
but this measure is not as stringent as prohibiting race tracks and 
surface treatment of disturbed areas.
    Clark County determined that section 90 requirements effectively 
prohibit dirt race tracks because it is not possible to

[[Page 2964]]

operate off-road vehicles, including dirt bikes and ATVs, on open 
areas/vacant lots and remain in compliance with the regulation. Where 
motor vehicle trespass is occurring on vacant lots greater than 5,000 
square feet, owners must take steps to prevent trespass and stabilize 
the surface. Even if motor vehicle use is authorized, where over 5,000 
cumulative square feet of surface has been disturbed, owners/operators 
must apply dust palliative (other than water) or gravel. These 
requirements would apply to any public or private lands where offroad 
racing occurs.
    The one public entity in Clark County that can effectively 
authorize use of public land for offroad racing events is the Bureau of 
Land Management. Clark County indicates that BLM is currently working 
to establish offroad racing courses outside the nonattainment area. The 
DAQM's policy prohibiting issuance of permits for offroad race tracks 
within the nonattainment area is described in a letter dated September 
5, 2002 from the DAQM to the BLM and in letters from the DAQM to other 
public agencies dated September 9, 2002.
    Clark County did not conduct a MSM evaluation specific to race 
tracks. Rather, the MSM evaluation for section 90 applies. We propose 
to find that the Clark County Plan provides for the implementation of 
BACM and for the inclusion of MSM for race tracks.
g. Section 0
    Section 0 was revised by Clark County at the same time sections 90 
through 94 were originally adopted (November 16, 2000). The section 0 
definitions that concern fugitive dust sources are integrally linked to 
the requirements found in sections 90 through 94. However, section 0 
also contains definitions that are not pertinent to sections 90 through 
94. For the purposes of this action, we have only evaluated the 
definitions concerning fugitive dust sources per section 90 through 94 
requirements and are proposing to approve only these sections into the 
SIP, rather than the entire section 0.
    The individual sections of section 0, November 16, 2000, we are 
proposing to approve into the Nevada PM-10 SIP include the following:

Section 0.25 ``Best Management Practices''
Section 0.33 ``Commercial and Residential Construction''
Section 0.36 ``Construction Activity''
Section 0.37 ``Control Measure''
Section 0.43 ``Disturbed Surface Area''
Section 0.45 ``Dust Palliative''
Section 0.46 ``Dust Suppressant''
Section 0.47 ``Easement''
Section 0.48 ``Easement Holder''
Section 0.51 ``Emergency''
Section 0.58 ``EPA or Administrator''
Section 0.65 ``Flood Control Construction''
Section 0.70 ``Fugitive Dust''
Section 0.81 ``Hearing Officer''
Section 0.84 ``Highway Construction''
Section 0.110 ``Nonroad Easement''
Section 0.111 ``Normal Farm Cultural Practice''
Section 0.114 ``Offroad Vehicle''
Section 0.117 ``Open Areas and Vacant Lots''
Section 0.120 ``Owner and/or Operator''
Section 0.127 ``Pave''
Section 0.132 ``PM-10 Nonattainment Area''
Section 0.133 ``PM-10''
Section 0.140 ``Public Road''
Section 0.141 ``Reclaimed Water''
Section 0.147 ``Road Easement''
Section 0.162 ``Trench''
Section 0.164 ``Unpaved Parking Lot''

Section 0.166 ``Vacant Lot''
    The current Nevada SIP contains a definitions rule titled ``Section 
1--Definitions'' submitted on November 17, 1981 and approved into the 
SIP by EPA on June 21, 1982. Our proposed incorporation of the 
specified section 0 definitions into the SIP would upgrade the SIP by 
adding several new definitions and by replacing two of the existing 
section 1 definitions. These two definitions include section 0.70 
``Fugitive Dust'' and section 0.114 ``Offroad Vehicle'', which would 
replace subsection 1.35 and subsection 1.64 of section 1, respectively.

G. Applicable SIP Rules

    In addition to section 1, the applicable SIP-approved fugitive dust 
rules that apply in Clark County include section 41 ``Fugitive Dust'' 
(submitted on July 24, 1979 and approved by EPA on August 27, 1981) and 
section 17 ``Permission to Disturb Topsoil'' (submitted on July 24, 
1979 and approved by EPA on August 27, 1981). Revisions to section 17 
were submitted on November 17, 1981 and approved by EPA on June 18, 
1982.
    We are proposing to revise the Nevada PM-10 SIP to incorporate 
sections 90, 91, 92, 93 (as adopted on November 20, 2001) and section 
94 (including the Section 94 Handbook and other referenced documents) 
(as adopted on November 16, 2000) of the Clark County Regulations. We 
are proposing to replace SIP-approved Clark County section 17. We are 
also proposing to add certain portions of Section 0 (as adopted on 
November 16, 2000) to the existing SIP-approved section 1, and replace 
two definitions in section 1, as previously identified in this notice.
    CAA section 110(l) prohibits approval of SIP revisions that would 
interfere with any applicable requirement concerning attainment and RFP 
or any other applicable requirement of the Act. As discussed in other 
sections of this document, we are proposing to approve the expeditious 
attainment and RFP demonstrations in the PM-10 State Implementation 
Plan for Clark County. These demonstrations are in large part dependent 
on approval of sections 90, 91, 92, 93, and 94 (including Handbook) and 
Clark County SIP commitments. Therefore, our proposed approval of these 
rules and SIP commitments will not adversely affect the Plan's 
provisions for expeditious attainment and RFP. These SIP revisions also 
satisfy all other applicable CAA requirements including implementation 
of BACM and the inclusion of MSM.

H. General SIP Requirements and Enforcement of Fugitive Dust Rules

    Section 110(a)(2)(E)(i) of the Clean Air Act requires that the 
implementation plan provide necessary assurances that the State (or the 
general purpose local government) will have adequate personnel, funding 
and authority under State law. Requirements for legal authority are 
further defined in 40 CFR part 51, subpart L (51.230-51.232) and for 
resources in 40 CFR 51.280.
    States and responsible local agencies must demonstrate that they 
have the legal authority to adopt and enforce provisions of the SIP and 
to obtain information necessary to determine compliance. SIPs must also 
describe the resources that are available or will be available to the 
State and local agencies to carry out the plan, both at the time of 
submittal and during the 5-year period following submittal.
    Section 110(a)(2)(C) of the Act requires SIPs to include a program 
to provide for the enforcement of SIP measures. The implementing 
regulation for this section is found at 40 CFR 51.111(a) and requires 
control strategies to include a description of enforcement methods 
including (1) procedures for monitoring compliance with each of the 
selected control measures, (2) procedures for handling violations, and 
(3) the designation of the agency responsible for enforcement.
    Section 110(a)(2)(E)(iii) of the Act requires SIPs to include 
necessary assurances that where a State has relied on a local or 
regional government, agency or instrumentality for the implementation 
of any plan provision, the State has responsibility for ensuring

[[Page 2965]]

adequate implementation of the such plan provision.
    With respect to CAA section 110(a)(2)(E)(iii), the State of Nevada 
has ultimate responsibility for ensuring the adequate implementation of 
the Clark County air quality program according to NRS 445B.520. This 
statute allows the State Environmental Commission to supersede a 
County's program when the Commission determines that a local air 
quality program is inadequate.
    The principal control measures in the Clark County Plan are the 
adopted requirements in sections 90 through 94 and the Plan's SIP 
commitments for unpaved shoulders and roads.
1. Staffing
    Clark County has committed to increase its enforcement staffing and 
thus enhance enforcement efforts. See Chapter 4, section 4.8.1 and 
appendix H, Resolution 02-00, July 27, 2001, of the Clark County Plan. 
Specifically, Clark County committed to hire 15 additional staff by 
December 31, 2001 to implement and enforce sections 90 through 94, 
including several enforcement officers, clerical and other support 
positions. Prior to the fulfillment of this SIP commitment, compliance 
for fugitive dust sources (per sections 17 and 41 of the Clark County 
Regulations) was being handled by 11 people total, seven (7) of which 
were field enforcement officers conducting inspections.
    The DAQM has provided us with the status of its SIP 
commitments.\42\ First, the DAQM met its commitment by hiring 15 new 
staff into the compliance division, 12 of which were hired as field 
enforcement officers to conduct inspections and handle cases for 
construction sites and vacant lots. The DAQM then exceeded its SIP 
commitment by hiring an additional seven (7) field enforcement officers 
in 2002. The Compliance Division now consists of a total of 44 
positions, with 22 field enforcement officers who spend approximately 
90 percent of their time on fugitive dust issues. The increased level 
of effort specifically being targeted towards fugitive dust sources is 
evidenced by the significant number of inspections and corrective 
action orders concerning fugitive dust sources in 2001 and 2002, which 
we address in subsequent paragraphs.
---------------------------------------------------------------------------

    \42\ See June 28, 2002 letter and attached RFP Report and 
October 1, 2002 letter from the DAQM to EPA.
---------------------------------------------------------------------------

    We address below other program areas that are key to improving 
compliance and which we believe form a solid program for the 
effectiveness of the County's efforts to control fugitive dust.
2. Inspection Program
    Clark County's enforcement staff utilizes the county Geographic 
Information System (GISMO) to obtain detailed aerial photographs to 
locate and identify large parcels of vacant land to inspect and 
characterize. The DAQM continues to expand the existing vacant land 
program by identifying and systematically inspecting the problem areas 
and the larger parcels.
    In calendar years 2001 and 2002 (as of September) combined, Clark 
County has conducted over 4,000 vacant land inspections. The Compliance 
Division has a member on staff who coordinates all activities and 
concerns with two government agency large vacant landowners, the Bureau 
of Land Management and the Bureau of Reclamation--in order to ensure 
close cooperation with these agencies.
    In calendar years 2001 and 2002 (as of September) combined, Clark 
County has conducted over 5,000 construction site inspections. 
Complaints are given priority for inspection; however, enforcement 
officers also inspect construction sites within their assigned area on 
a routine basis, including non-permitted construction activities as 
they are encountered in the field.
3. Enforcement Program
    Clark County relies upon two options for handling noncompliant 
sources: issuing a Corrective Action Order (CAO) or a Notice of 
Violation (NOV). In 2001, the County issued 1,316 CAOs and as of 
September 2002 has issued 1,775 CAOs. In 2001, the County issued 57 
NOVs and as of September 2002 has issued 133 NOVs. The penalties 
assessed for the two years combined amount to $719,372. CAOs are 
generally written for infractions that are not substantial enough to 
warrant a NOV, allowing source owners/operators a first-time chance to 
comply. NOVs are issued for more serious violations. Should owners/
operators fail to comply with a CAO, it becomes a NOV with associated 
penalties.
    Section 7 provides that the Hearing Board Officers be selected by 
the District Board of Health and have the authority to levy penalties 
for alleged violations in accordance with section 9 of Clark County 
regulations, which contains the minimum penalties for violations of 
fugitive dust requirements. The minimum penalty for limiting visible 
emissions is $2,000. The minimum penalty for not complying with other 
control measure provisions is $1,000. Minimum penalties for failing to 
comply with administrative requirements related to permit conditions is 
$500 and $250 for other administrative requirements. Clark County 
compared these minimum penalties for dust violations to those of other 
air regulatory agencies and found that they were among the highest in 
the nation.
4. Public Outreach/Education
    Public outreach and education consists of staff training, educating 
the regulated parties, developing good working relationships with other 
involved parties such as the cities, and making the program more 
understandable. Increased education of both inspectors and the 
regulated industry increases compliance.
    Public outreach efforts in which Clark County has engaged to 
improve compliance for construction sites include publishing and 
distributing a manual that summarizes the section 94 and section 94 
Handbook requirements in an easy-to-comprehend format. Also, dust 
control classes and educational workshops are regularly offered by the 
DAQM's Compliance Division. The construction site superintendent or 
designated on-site representative and water truck and water pull 
drivers for each construction project are required per section 94 to 
have successfully completed a Dust Control Class and all individuals 
required to attend must successfully complete the Dust Control Class at 
least once every three years. In addition, as of 2002, the DAQM has 
conducted a special training effort per the section 94 requirement for 
a responsible person to monitor dust (i.e. ``Dust Control Monitor'') on 
sites with more than 50 acres of disturbed surface. To date, two Dust 
Control Monitor classes have been held with over 90 participants.
    In order to increase awareness among vacant lot owners/operators of 
the disturbed vacant lot requirements, Clark County prepared and 
distributed a brochure summarizing the section 90 requirements to over 
40,000 vacant landowners.
5. Program Evaluation and Tracking
    Clark County tracks the number of inspections, CAOs, NOVs, 
penalties assessed and penalties collected for fugitive dust and other 
sources and provides quarterly reports containing this information to 
EPA.
    Clark County tracks progress of government agencies on their 
unpaved road and paved road SIP commitments through a PM-10 SIP 
Implementation Working Group and an Unpaved Road Ad Hoc Committee. 
These groups are

[[Page 2966]]

comprised of DAQM planning and compliance staff and staff from the 
County and City public works agencies. Unpaved road paving is 
documented using an extranet site and the unimproved shoulders program 
will be reviewed through submittal of annual reports to the DAQM.\43\ 
Also, the Public Works Departments in Clark County routinely track 
paved road performance and maintenance by checking the condition of 
paved roads in their respective jurisdictions.
---------------------------------------------------------------------------

    \43\ Appendix L, pg. L-12 of the Plan.
---------------------------------------------------------------------------

6. Conclusion
    We propose to find that the Clark County PM-10 Plan adequately 
provides for the enforcement of the principal measures relied on for 
attainment and that Clark County has provided adequate descriptions of 
its enforcement methods as required by our regulations.
    We also propose to find that the implementing agencies for the 
Clark County Plan have adequate resources for implementing their 
respective commitments that are included in the submitted Plan and that 
the Plan adequately describes the resources that are available or will 
be available to the State and local agencies to carry out the Plan, 
both now and over the next 5 years.

I. Demonstration of Attainment and Attainment Date Extension

    The Clark County Plan contains an analysis that demonstrates 
attainment of the annual PM-10 standard by December 31, 2001. Clark 
County predicted that an annual reduction of 5.66 percent, equivalent 
to 9,657 tons valley-wide and 303 tons for the J.D. Smith micro-
inventory area, is needed to attain the annual 50 [mu]g/m\3\ standard, 
given an estimated uncontrolled concentration of 53 [mu]g/m\3\. The 
valley-wide rollback modeling predicts annual PM-10 concentrations to 
be 46.2 [mu]g/m\3\ in 2001. The corresponding microinventory projection 
for J.D. Smith, the exceeding site, is 48.5 [mu]g/m\3\, also less than 
50 [mu]g/m\3\. Together, these demonstrate attainment of the annual PM-
10 standard by 2001. We propose to find this demonstration adequate. 
The adequacy of the demonstration is further supported by information 
provided by the DAQM to EPA \44\ indicating that the three-year annual 
average (1999-2001) of the microscale sites is below the 50 [mu]g/m\3\ 
standard.
---------------------------------------------------------------------------

    \44\ June 28, 2002 letter from the DAQM to EPA with attached 
June 2002 Reasonable Further Progress Report.
---------------------------------------------------------------------------

    Clark County has requested an extension of the attainment date for 
the 24-hour 150 [mu]g/m\3\ PM-10 standard. Section 188(e) of the Act 
allows us to extend the attainment date for a serious area for up to 
five years beyond 2001 if attainment by 2001 is impracticable. However, 
before we may grant an extension of the attainment date, the State must 
first:
    1. Apply to us for an extension of the PM-10 attainment date beyond 
2001,
    2. Demonstrate that attainment by 2001 is impracticable,
    3. Have complied with all requirements and commitments applying to 
the area in its implementation plan,
    4. Demonstrate to our satisfaction that its serious area plan 
includes the most stringent measures that are included in the 
implementation plan of any state and/or are achieved in practice in any 
state and are feasible for the area, and
    5. Submit a demonstration of attainment by the most expeditious 
alternative date practicable.
    We evaluate the Clark County serious area plan's compliance with 
each of these requirements below.
1. Apply for an Extension
    The documentation supporting Clark County's extension request is 
found in Chapter 7 of the Plan. This extension request is an integral 
part of the Clark County Plan and was subject to public hearing along 
with the rest of the plan, including the demonstration that the area 
will attain the 24-hour standard by the earliest alternative date 
practicable.
2. Demonstrate the Impracticability of Attainment by December 31, 2001
    Clark County's determination that demonstrating attainment of the 
24-hour standard by 2001 is impracticable is primarily based upon the 
need for increased enforcement staffing, which could not be completed 
until the end of 2001. Clark County conservatively assumes that the 
rule effectiveness of its regulations in 2001 is half of what it will 
need to be in 2006 to demonstrate attainment of the 24-hour standard.
    Also, with respect to the unpaved roads schedule, Clark County 
indicates that the maximum benefit that will be realized at the end of 
2003 from the appropriated CMAQ funding cannot practicably be achieved 
earlier due to funding limitations each year. Notwithstanding, we note 
from the DAQM's June 2002 RFP Report that the responsible entities have 
exceeded the Section 91 required 33 percent paving of roads subject to 
the rule by 2001 and reported paving 86 percent, or a total of 55 of 
the 64 mile inventory of unpaved roads with 150 vehicle trips per day.
    With respect to improvements to paved road shoulders, Clark County 
has committed to stabilize 33 miles of paved road shoulders by the end 
of 2003 using appropriated CMAQ funds and all shoulders by 2006. The 
remaining shoulders have a later implementation date given that new 
CMAQ funds will need to be appropriated and first committed towards the 
carbon monoxide transportation demand management program. Thus, earlier 
implementation would be impracticable.
    The modeled valley-wide 24-hour value for 2001 is 209 [mu]g/m\3\. 
Although this is a significant reduction from the projected design day 
value of 281 [mu]g/m\3\, it still falls far short of the 150 [mu]g/m\3\ 
standard.
    Thus, we propose to find that Clark County has demonstrated the 
impracticability of meeting the 24-hour standard by 2001.
3. Complied With Commitments and Requirements in the SIP
    All measures upon which Clark County is relying to meet the 
applicable CAA requirements for a Serious Area PM-10 plan are included 
or referenced in the current June 2001 Plan, as amended by Clark County 
in November 2002.
4. Include the Most Stringent Measures
    Clark County identified candidate MSM in the context of its 
analysis to identify potential BACM, generally finding that control 
measures being implemented in other PM-10 serious nonattainment areas 
in the western U.S. were the most stringent controls implemented by 
others for the types of fugitive PM-10 sources requiring control in the 
Las Vegas Valley.
    In the Clark County Plan, after a comprehensive list of candidate 
MSM was developed, each measure was screened against the corresponding 
Clark County measure to identify those with more restrictive emission 
limitations, more extensive lists of affected sources, fewer 
exemptions, and/or one or more substantive regulatory provisions not 
found in the Clark County measure. Clark County includes a measure-by-
measure MSM comparison in Chapter 6 of the Plan.
    Based on our analysis of the Clark County Plan, we propose to find 
that it demonstrates to our satisfaction inclusion of the most 
stringent measures that are included in the implementation plan of any 
State, or are achieved in practice in any State, and can be feasibly 
implemented in the Clark County area.

[[Page 2967]]

5. Demonstrate Expeditious Attainment
    For the reasons discussed below, we propose to find that the Clark 
County Plan demonstrates attainment by the earliest date practicable 
after December 31, 2001 as required by CAA section 189(b)(1)(A)(ii). We 
also propose to find that: The attainment demonstration relies on 
control measures that either are approved or have been proposed for 
approval and meet our SIP enforceability criteria; the emissions 
estimates credited to these measures in the attainment demonstration 
are reasonable; and the measures are being implemented on a schedule 
that is as expeditious as practicable and will result in attainment by 
the earliest practicable date.
a. Air Quality Modeling
    The attainment demonstration for the 24-hour standard in the Clark 
County Plan is divided into two parts, a microscale analysis and a 
regional analysis. The microscale part evaluates 24-hour exceedences at 
five monitoring sites in the Las Vegas. The regional part evaluates 24-
hour levels throughout the rest of the Clark County nonattainment area.
    Clark County relies upon an emissions ``rollback'' model for the 
attainment demonstrations. EPA's guidelines \45\ allow the need for 
case-by-case approaches in circumstances when recommended dispersion 
models are not available or applicable and where area sources are the 
predominant component of PM-10. To predict future concentration, the 
current concentration is reduced or ``rolled back'' by the same 
fractional amount that emissions are reduced. In recognition of the 
special characteristics of fugitive dust-dominated areas, we believe an 
attainment demonstration based on proportional rollback of one or more 
microinventories is a reasonable approach and is consistent with EPA 
guidance, as long as the microinventory areas are representative of 
worst case conditions, and the resulting emission controls are applied 
throughout the area.
---------------------------------------------------------------------------

    \45\ Guideline On Air Quality Models, 2001, sections 7.2.1 and 
7.2.2.
---------------------------------------------------------------------------

    We have evaluated the five microinventory areas mentioned 
previously in this document and find that they contain varying source 
category mixes and span a range of conditions that occur in the Las 
Vegas Valley. By showing that the chosen microinventory areas are 
representative of conditions leading to PM-10 NAAQS exceedences, and by 
then applying the controls shown to be needed in these microareas to 
the entire nonattainment area, Clark County has followed an acceptable 
procedure for demonstrating attainment.
b. Control Measures Relied on for Attainment
    For demonstrating attainment of the annual and 24-hour PM-10 
standards, the Clark County Plan relies on reductions in directly-
emitted PM-10 from the following measures: Section 90 controls for 
disturbed vacant land, section 92 controls for unpaved parking 
lots,\46\ section 94 (including Handbook) controls for construction 
sites, section 91 and government agency SIP commitment controls for 
unpaved roads, and section 93 and government agency SIP commitment 
controls for unpaved road shoulders (within the paved road dust 
category).
---------------------------------------------------------------------------

    \46\ Emission reductions for section 92 controls were only 
specifically calculated for the two microscale areas that included 
unpaved parking as opposed to a valley-wide basis. These microscale 
areas play a role in the 24-hour but not annual attainment 
demonstration. Clark County did not prepare a separate valley-wide 
inventory for unpaved parking lots apart from the disturbed vacant 
land inventory. Thus, reductions attributable to the section 92 
controls are only implicitly assumed, for purposes of the annual 
attainment demonstration, within the larger valley-wide emission 
reductions anticipated from disturbed vacant land.
---------------------------------------------------------------------------

    For the 24-hour attainment demonstration, Clark County models 
controlled valley-wide future concentrations for the years 2001 and 
2006 as well as controlled 2006 concentrations at each of the five 
microscale sites. We have evaluated the emissions reductions credited 
to each measure in the attainment demonstrations to ensure they are 
reasonable. Three factors considered include:
    1. Emissions reductions from controls applied (e.g. percent 
reduction achieved through paving or chemical stabilization);
    2. Rule penetration (i.e. percentage of sources within the total 
source category that the rule or measure will impact); and
    3. Rule effectiveness (i.e. the expected rate of compliance with a 
rule or measure).
    We find that the emission reduction estimates for each source 
category are consistent with available research on the applicable 
control methods, rule penetration estimates are reasonable based on 
emissions inventory data, and rule effectiveness estimates are 
reasonable given the schedule for adoption of measures and other 
factors. Emissions reductions credited based on these estimates are 
appropriately applied in the attainment demonstrations. For more 
information on the quantification of emission reductions, we refer to 
the TSD associated with this rulemaking.
    We are also proposing that the measures relied on for attainment 
are being expeditiously implemented. Section 90, 91, 92, 93 and 94 
requirements all applied well before adoption of the Clark County Plan 
in June 2001. While Clark County has revised the original SIP 
commitment deadline for adopting certain revisions to its fugitive dust 
regulations to March 31, 2003, these revisions provide incremental 
reductions above an already-adopted baseline that should achieve 
substantial immediate reductions. Therefore, we believe the extension 
is reasonable and does not impact our finding that the Plan provides 
for expeditious implementation of measures. Finally, Clark County's SIP 
commitment for hiring additional staff to implement and enforce 
fugitive dust controls was established with an expeditious timeframe 
for all positions to be filled by the end of 2001. Clark County has not 
only met, but exceeded this commitment.
6. Other Factors That EPA May Consider
    CAA section 188(e) lists five additional factors that we may 
consider in deciding whether to grant an extension and the length of 
that extension. These include: (1) The nature and extent of the 
nonattainment problem; (2) the types and numbers of sources or other 
emitting activities in the area (including the influence of 
uncontrollable natural sources and international transport); (3) the 
population exposed to concentrations in excess of the standard; (4) the 
presence and concentration of potentially toxic substances in the mix 
of particulate emissions in the area; and (5) the technological and 
economic feasibility of various control measures.
    In evaluating these factors, we have focused on the nature and 
extent of the nonattainment area problem, the types of sources 
contributing to the problem, and the ability of the County to control 
these sources. Fugitive dust sources dominate the emissions inventory 
in the Clark County PM-10 nonattainment area. Controls for these 
sources are well known (paving, wetting surfaces, etc.) and have been 
adopted; however, the number of sources and nature of sources make 
education, outreach and enhanced enforcement necessary to assure full 
compliance with those controls. In addition, costs for paving roads and 
stabilizing shoulders necessary to

[[Page 2968]]

reduce PM-10 emissions are high and funds are only available over a 
number of years. These factors generally support a longer time frame 
for attainment.
7. Conclusion on Extension Request
    Based on our review of the Clark County Plan and our proposed 
determination that it meets the requirements necessary for granting an 
extension of the attainment date under CAA section 188(e), we are 
proposing to grant a five-year extension of the attainment date for the 
24-hour PM-10 standard in the Clark County PM-10 serious nonattainment 
area from December 31, 2001 to December 31, 2006.

J. Reasonable Further Progress and Quantitative Milestones

    CAA section 172(c)(2) requires nonattainment plans to provide for 
reasonable further progress (RFP). Section 171(1) of the Act defines 
RFP as ``such annual incremental reductions in emissions of the 
relevant air pollutant as are required by this part (part D of title I) 
or may reasonable be required by the Administrator for the purpose of 
ensuring attainment of the applicable national ambient air quality 
standard by the applicable date.''
    CAA section 189(c) also requires PM-10 plans demonstrating 
attainment to contain quantitative milestones which are to be achieved 
every 3 years until the area is redesignated attainment and which 
demonstrate RFP. These quantitative milestones should consist of 
elements that allow progress to be quantified or measured. Addendum at 
42016.
    Clark County identified milestone achievement dates of 2003 and 
2006 with respect tp the 24-hour standard. The milestones have been 
addressed by quantifying emission reductions which result from the 
implementation of the committed control measures after predicted growth 
has occurred. Emissions by 2003 are projected to be reduced 
substantially to 276.48 tons per day, with 77.23 additional tons per 
day reductions occurring between 2003 and 2006, resulting in 199.25 
tons per day. Clark County indicates that total emissions under 210.70 
tons per day should result in attainment of the 24-hour standard. RFP 
Reports are due at the end of 2003 and 2006, which correspond with 
Clark County's milestone achievement dates.
    The milestones for the 24-hour standard are based on reasonable 
assumptions that are consistent with the implementation schedules for 
the measures in the plan and with the RFP demonstrations. For these 
reasons, we propose to find that the Plan meets the quantitative 
milestone requirement in CAA section 189(c)(1).

K. Contingency Measures

    Section 172(c)(9) of the Clean Air Act requires that implementation 
plans provide for the implementation of specific measures to be 
undertaken if the area fails to make RFP or attain by its attainment 
deadline. These contingency measures are to take effect without further 
action by the State or the Administrator. The Act does not specify how 
many contingency measures are necessary nor does it specify the level 
of emission reductions they must produce.
    The purpose of contingency measures is to ensure that additional 
emission reductions beyond those relied on in the attainment and RFP 
demonstrations are available if there is a failure to make RFP or 
attain by the applicable attainment date. These additional emission 
reductions will assure continued progress towards attainment while the 
SIP is being revised to fully correct the failure. To ensure this 
continued progress, we recommend that contingency measures provide 
emission reductions equivalent of one year's average increment of RFP. 
Addendum at 42016.
    The following contingency measures were adopted by Clark County 
Health District Board of Health Resolution 03-00 on July 27, 
2000.
    1. Reduce the threshold for site-specific dust mitigation plan 
requirements for construction activities from ten acres to five acres;
    2. Require paving/stabilization of all unpaved roads with 
= 100 average daily vehicle trips;
    3. Provide for at least two additional field enforcement officers 
above and beyond those staff increases committed to in the State 
Implementation Plan;
    4. Increase minimum penalties for violations of Air Quality 
Regulations for fugitive dust; and
    5. Reduce the size threshold for requiring a dust control monitor 
(coordinator) at construction sites.
    Clark County describes that the entire set of contingency measures 
will be automatically implemented if Clark County fails to meet the 
projected 2003 emissions reduction milestone. We note that Clark County 
has already implemented Contingency Measure 3 for field enforcement 
officer staff increases above and beyond the staff increases committed 
to in the Plan. Clark County estimates the emissions reduction benefit 
from the contingency measures to be 1,373 tons per year in total. This 
annual reduction exceeds the annual average increment of RFP.
    The contingency measures identified in the Plan have been adopted 
but are not credited in the attainment, RFP or milestone demonstrations 
for the 24-hour standard and are not necessary to demonstrate 
expeditious attainment of the standard.
    Therefore, we propose to find that the Plan provides for the 
implementation of contingency measures for the 24-hour standard as 
required by CAA section 172(c)(9). This proposal is based on our 
analysis that these contingency measures comply with applicable CAA 
requirements and EPA policy.

L. Administrative Requirements

    Under Executive Order 12866 (58 FR 51735, October 4, 1993), this 
proposed action is not a ``significant regulatory action'' and 
therefore is not subject to review by the Office of Management and 
Budget. For this reason, this proposed action is also not subject to 
Executive Order 32111, ``Actions Concerning Regulations That 
Significantly Affect Energy Supply, Distribution, or Use'' (66 FR 
28355, May 22, 2001). This proposed action merely approves state law as 
meeting federal requirements and imposes no additional requirements 
beyond those imposed by state law. Accordingly, the Administrator 
certifies that this proposed rule will not have a significant economic 
impact on a substantial number of small entities under the Regulatory 
Flexibility Act (5 U.S.C. 601 et seq.). Because this rule proposes to 
approve pre-existing requirements under state law and does not impose 
any additional enforceable duty beyond that required by state law, it 
does not contain any unfunded mandate or significantly or uniquely 
affect small governments, as described in the Unfunded Mandates Reform 
Act of 1995 (Pub. L. 104-4). This rule also does not have a substantial 
direct effect on one or more Indian tribes, on the relationship between 
the Federal Government and Indian tribes, or on the distribution of 
power and responsibilities between the Federal Government and Indian 
tribes, as specified by Executive Order 13175 (65 FR 67249, November 9, 
2000), nor will it have substantial direct effects on the States, on 
the relationship between the national government and the States, or on 
the distribution of power and responsibilities among the various levels 
of government, as specified in Executive Order 13132 (64 FR 43255, 
August 10, 1999), because it merely approves a state rule implementing 
a federal standard, and does not alter the relationship or the 
distribution of power

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and responsibilities established in the Clean Air Act. This proposed 
rule also is not subject to Executive Order 13045 (62 FR 19885, April 
23, 1997), because it is not economically significant.
    In reviewing SIP submissions, EPA's role is to approve state 
choices, provided that they meet the criteria of the Clean Air Act. In 
this context, in the absence of a prior existing requirement for the 
State to use voluntary consensus standards (VCS), EPA has no authority 
to disapprove a SIP submission for failure to use VCS. It would thus be 
inconsistent with applicable law for EPA, when it reviews a SIP 
submission, to use VCS in place of a SIP submission that otherwise 
satisfies the provisions of the Clean Air Act. Thus, the requirements 
of section 12(d) of the National Technology Transfer and Advancement 
Act of 1995 (15 U.S.C. 272 note) do not apply. This proposed rule does 
not impose an information collection burden under the provisions of the 
Paperwork Reduction Act of 1995 (44 U.S.C. 3501 et seq.).

List of Subjects in 40 CFR Part 52

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

    Authority: 42 U.S.C. 7401 et seq.

    Dated: January 9, 2003
Wayne Nastri,
Regional Administrator, Region IX.
[FR Doc. 03-1145 Filed 1-21-03; 8:45 am]
BILLING CODE 6560-50-P