[Federal Register Volume 71, Number 81 (Thursday, April 27, 2006)]
[Notices]
[Pages 24903-24908]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 06-3998]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

[Docket No. FAA-2006-24508]


Draft General Conformity Determination for Proposed Operations of 
Southwest Airlines Co. at Denver International Airport, Denver, CO

AGENCY: Federal Aviation Administration (FAA), Department of 
Transportation (DOT).

ACTION: Notice of Draft General Conformity Determination.

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SUMMARY: The FAA is issuing this notice to advise the public that a 
Draft General Conformity Determination (DGCD) for Proposed Operations 
of Southwest Airlines Co. (Southwest) at Denver International Airport 
(DEN) has been prepared. In accordance with Section 176(c) of the Clean 
Air Act, FAA has assessed whether the emissions that would result from 
FAA's action in approving the proposed operation specifications 
(OpSpec) for Southwest's proposed operations at DEN conform with the 
Colorado State Implementation Plan (SIP).

DATES: Submit comments on or before May 30, 2006.

ADDRESSES: You may submit comments, identified by docket no. FAA-2006-
24508 by any of the following methods:
     DOT docket Web site: Go to http://dms.dot.gov and follow 
the instructions for sending your comments electronically.
     Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your 
comments electronically.
     Mail: Docket Management Facility, U.S. Department of 
Transportation, 400 Seventh Street, SW., Nassif Building, Room PL-401, 
Washington, DC 20591.
     Fax: (202) 493-2251.
     Hand delivery: Room PL-401 on the plaza level of the 
Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
    After all comments are reviewed and addressed, a notice of 
availability of the Final General Conformity Determination will be 
published.
    Instructions: All submissions received must include the agency name 
and docket number or Regulatory Information Number (RIN).
    For Technical Information Contact: Joan Seward, All Weather 
Operations Program Manager, ASW-230.1, FAA SW Region Headquarters, 2601 
Meacham Blvd., Fort Worth, TX 76137, telephone (817) 222-5278, e-mail: 
[email protected].

SUPPLEMENTARY INFORMATION: In December of 2005, Southwest announced its 
intent to begin scheduled service at DEN commencing in January 2006. As 
required by Title 14 of the Code of Federal Regulations (14 CFR) 
119.51, Southwest applied to the FAA to amend Southwest's OpSpecs to 
include DEN, thereby authorizing Southwest to conduct DEN service. The 
request to the FAA detailed Southwest's startup plans, commencing on 
January 3, 2006, with 13 daily landing/take-off cycles (LTO),\1\ 
equating to a total of 26 operations, and contained other information 
for the FAA to conduct the environmental review required under the 
regulations implementing the National Environmental Policy Act (NEPA) 
(40 CFR 1500-1508), section 176(c) of the Clean Air Act (40 CFR 93.150 
et seq.), and by FAA Order 1050.1E, Environmental Impacts: Policies and 
Procedures. At that time Southwest indicated an interest in increasing 
operations to as many as 50 or 60 daily operations at DEN, but agreed 
to maintain operations at DEN below de minimis levels until a General

[[Page 24904]]

Conformity Determination could be completed.
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    \1\ For clarification, the phrase ``one round trip'' is 
synonymous with a landing/takeoff cycle (LTO). The LTO consists of 
an aircraft taxiing from the terminal gate area to the runway, 
taking off by accelerating down the runway until 1,000 feet off the 
ground, climbing to the altitude of the local mixing height, 
returning on approach by descending from the mixing height to the 
runway, and finally completing the cycle by taxiing from the runway 
to the gate. An aircraft operation is defined as either a landing or 
a takeoff. Therefore, one LTO cycle is equal to two aircraft 
operations.
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    The FAA issued an OpSpec to Southwest for this initial level of 
activity accompanied by an environmental categorical exclusion dated 
December 14, 2005, determining that the daily 13 LTOs were below de 
minimis emission levels and were not regionally significant. Therefore, 
the no further determination was required under the General Conformity 
rule.
    Southwest subsequently announced a scheduled increase of service 
planned for March 2006 with an additional 9 daily LTOs, bringing the 
total expected daily LTOs to 22. This General Conformity Determination 
addresses FAA's proposed Federal action to amend Southwest's OpSpecs to 
accommodate future operations as high as 60 daily LTOs at DEN (hereto 
known as the ``Proposed Action''). The information presented in this 
DGCD demonstrates conformance with Colorado's SIPs and substantiates 
that the net emissions resulting from Southwest's increased service at 
DEN are not regionally significant.

Air Quality Designations for the Denver Metropolitan Area

    DEN is owned and operated by the City and County of Denver, and is 
located within the Denver Metropolitan Area (DMA) for air quality 
planning purposes. The DMA is designated as attainment for the criteria 
pollutants sulfur dioxide (SO2), nitrogen dioxide 
(NO2), lead, and particulate matter with aerodynamic 
diameter of 2.5 micrometers or less (PM2.5).
    The DMA is an Environmental Protection Agency (EPA) designated 
attainment/maintenance area for the criteria pollutants carbon monoxide 
(CO), particulate matter with aerodynamic diameter of 10 micrometers or 
less (PM10), and the 1-hour ozone national ambient air 
quality standard (NAAQS). In addition, DEN is located in an Early 
Action Compact (EAC) area for the 8-hour ozone standard, which has a 
deferred air quality designation date of December 31, 2006.
    Pursuant to the Clean Air Act, Federal actions in nonattainment and 
maintenance areas are required to conform with SIPs to either bring an 
area into compliance with the NAAQS or maintain compliance with the 
NAAQS.
    FAA approval to amend Southwest's OpSpecs for DEN constitutes a 
Federal action required to conform to Colorado's SIPs for CO, 
PM10, and the EAC requirements for the 8-hour ozone 
standard.

General Conformity Applicability Analysis

    Section 176(c) of the Clean Air Act prohibits the Federal 
government from engaging in, supporting, providing financial assistance 
for, licensing, permitting, or approving any activity that does not 
conform to an applicable implementation plan. A general conformity 
determination may be required for each pollutant where the net direct 
and indirect emissions in a nonattainment or maintenance area caused by 
the action exceed de minimis levels (40 CFR 93.151(b)). In addition to 
the de minimis applicability analysis, a conformity evaluation of 
Federal actions must also demonstrate the Proposed Action does not 
constitute a regionally significant action, which is defined as an 
action that contributes 10 percent or more of total basin-wide 
emissions.
    DMA's pollutants of concern for general conformity purposes include 
CO, PM10, and the precursors of ozone, namely volatile 
organic compounds (VOCs) and oxides of nitrogen (NOX).\2\ An 
analysis must be performed to determine if the net annual emissions of 
these pollutants resulting from the Proposed Action exceed General 
Conformity de minimis thresholds. For DMA, the General Conformity de 
minimis thresholds are 100 tons per year for each pollutant of concern.
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    \2\ Ozone is formed in the atmosphere rather than being directly 
emitted from sources. Ozone forms as a result of volatile organic 
compounds (VOCs) and oxides of nitrogen (NOX) reacting in 
the presence of sunlight in the atmosphere. VOCs and NOX 
are termed ``ozone precursors'' and their emissions are regulated in 
order to control the creation of ozone. Aircraft engine emissions 
data is in the form of ``total hydrocarbons'' or HC. For the 
purposes of this analysis, HCs are conservatively assumed equivalent 
to VOCs.
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Emissions Inventory

    To determine the net effect of the proposed project, an emissions 
inventory of reasonably foreseeable, direct, and indirect emissions 
caused by the Federal action was performed to calculate the difference 
between the Proposed Action scenario--Southwest's foreseeable maximum 
activity level at DEN, and the No Action scenario--no service by 
Southwest at DEN.\3\ The evaluation was performed using the FAA's 
Emissions and Dispersion Modeling System (EDMS) version 4.4. Under the 
Proposed Action, no facility improvements would required (e.g., new 
parking facilities, aircraft gates, etc.) to accommodate the Proposed 
Project. Therefore, the sources considered in the emissions inventory 
were limited to aircraft operations and supporting equipment (ground 
support equipment (GSE) and auxiliary power unit (APU)), surface 
transportation, and parking lots.
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    \3\ For the purposes of this analysis, FAA has taken the 
conservative approach of considering the No Action scenario to 
include no Southwest operations at DEN. Although Southwest began 
initial operations at DEN in January of 2005, Southwest agreed to 
limit operations to levels determined to be de minimis to 
accommodate the preparation of a General Conformity Determination of 
up to 60 LTO's per day.
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Aircraft and Supporting Equipment Emissions

    Under the No Action alternative, Southwest's operations would not 
be introduced at DEN, therefore no emissions from aircraft operations 
would occur. Similarly, no change in either APU emissions or (GSE) 
emissions would occur. Although the extent and timing of potential 
increases in Southwest's flight activity in the Proposed Project are 
imprecise, the airline's business plan indicates that earliest possible 
calendar year that the maximum foreseeable aircraft activity of 60 
daily LTOs could be achieved is 2007. Under the Proposed Action 
scenario, aircraft emissions were quantified based on this maximum 
foreseeable level and conservatively assumed to occur every day of the 
year for a total of 10,950 LTOs per year. To match Southwest's fleet 
and registered engines, emissions were calculated from CFM56-3B1, 
CFM56-3B2, CFM56-7B22, and CFM56-7B24 engines proportionately to the 
number of aircraft/engine combinations registered in Southwest's 
national fleet (see Table 1).

[[Page 24905]]



                 Table 1.--Southwest Aircraft Information and Potential Maximum Activity at DEN
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                                                                            Percent of
                                                                National     national     Maximum      Maximum
          Aircraft type                      Engine            quantity*      fleet      daily LTOs  annual LTOs
                                                                            (percent)
----------------------------------------------------------------------------------------------------------------
B733/B735........................  CFM56-3B1................          202         47.5           28       10,220
B733.............................  CFM56-3B2................           17          4.0            2          730
B737-700.........................  CFM56-7B22...............          204         48.0           29       10,585
B737-700.........................  CFM56-7B24...............            2          0.5            1          365
                                  ------------------------------------------------------------------------------
    Totals.......................  .........................          425          100           60      21,900
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* BACK database, April 2005.

    Southwest has indicated that it will use the available gate 
electrification at DEN. Gate electrification supplies power to an 
aircraft while parked at airport gates by enabling connection of the 
aircraft's systems to 400hz electrical power. The result is that the 
use of the aircraft's auxiliary power units (APUs) is reduced, which, 
in turn, reduces the associated combustion pollutants. Typically, with 
gate electrification, APU usage is minimized to approximately 8 minutes 
per LTO. Southwest employs Allied Signal model GTCP85-129 APUs on their 
B737-300s and Allied Signal model 1319B APUs on their B737-700s.
    Southwest has identified the individual types and quantities of 
ground support equipment (GSE), and time duration dedicated to each 
aircraft LTO. Table 2 presents the GSE information that was used to 
calculate emissions for the Proposed Action scenario.

        Table 2.--Southwest GSE Fleet Information per LTO at DEN
------------------------------------------------------------------------
                                                              Minutes of
                                                              operation
       GSE description          Quantity         Fuel        per vehicle
                                                               per LTO
------------------------------------------------------------------------
Aircraft Tug................            1  Diesel..........            5
Baggage Tug.................            2  Electric........           20
Lavatory Truck..............            1  Diesel..........           10
Baggage Belt Loader.........            2  Diesel..........           20
Hydrant Fueling Truck.......            1  Diesel..........          10
------------------------------------------------------------------------
Source: Southwest Airlines, 2005.

Surface Transportation Emissions

    Under the No Action alternative, Southwest's operations would not 
be introduced at DEN, therefore no additional emissions from increased 
surface transportation to/from DEN would occur. As a result of the 
Proposed Action, the employees of Southwest Airlines will induce new 
origin and destination (O&D) traffic to and from DEN. Over the years, 
the City and County of Denver has worked with the Denver Regional 
Council of Governments (DRCOG), which is the metropolitan planning 
organization (MPO) for the DMA, to include airport-related O&D traffic 
and emissions in DRCOG's regional traffic and air quality models, 
respectively. DRCOG estimates and forecasts vehicle miles traveled 
(VMT) for the region by compiling traffic data, population data, and 
employment data. Specifically, DRCOG estimates O&D traffic for DEN 
based upon data supplied by the City and County of Denver. DRCOG then 
models all traffic and associated emissions for transportation 
conformity purposes. This General Conformity Determination does not 
include emissions from Southwest Airlines employee traffic because 
DRCOG and the City and County of Denver have already taken steps to 
ensure that future employee traffic, such as Southwest's, and the 
associated future emissions are included in the conforming regional 
transportation plan for the DMA.

Parking Lot Emissions

    In the No Action alternative, no additional parking lot emissions 
would be generated from passengers or Southwest employees. The increase 
in parking lot emissions resulting from the increased Southwest 
employee vehicular traffic to DEN associated with the proposed action 
was calculated using the assumption that each proposed Southwest 
employee would arrive and depart DEN daily in the employee's own 
vehicle.

Results of the Emissions Inventory

    For determining general conformity applicability, the net increases 
of each pollutant of concern, if any, is determined by calculating the 
difference in emissions between the Proposed Action--taking into 
account not only additional emissions resulting from the action itself, 
but also any decreases in emissions which may result--and the No Action 
alternative. Table 3 presents the total emissions increase from the 
Proposed Action and the comparison to the General Conformity de minimis 
thresholds. The Proposed Action exceeds the de minimis thresholds for 
the pollutants of CO and NOX. As a result, a General 
Conformity determination is required.\4\
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    \4\ Although not required because emissions are above de 
minimis, Table 4 provides the estimated emission contributions from 
the Proposed Action in comparison to the regional budget levels from 
the various SIP documents, both existing and future plans. The 
common assumption in these values is that the annual tons of 
emissions estimated from the Proposed Action are evenly distributed 
across 365 days of the year. The FAA is aware that contribution of 
emissions from the proposed Southwest activity will vary by day, 
week, month, and season. However, the overall daily emission 
contributions from the Proposed Action is so low relative to 
regional inventories that further estimates of daily emission 
contributions from the Proposed Action will not change the 
determination. Therefore, the emissions from the Proposed Action are 
not regionally significant.

[[Page 24906]]



        Table 3.--Net Emission Increases From the Proposed Action and Comparison to De Minimis Thresholds
                                                 [Tons per year]
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            Category                  CO          VOC         NOX              SOX               PM10/PM2.5
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Aircraft........................     260.798      22.754     195.110  19.413..............  2.199
APU.............................       3.999       0.269       2.052  0.358...............  unavailable
GSE.............................       2.543       0.660       6.889  1.216...............  0.530
Parking.........................      <0.001      <0.001      <0.001  <0.001..............  <0.001
    Total.......................     267.339      23.682     204.051  20.985..............  2.728
ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½-------------------------------------------------------------------------------
de minimis threshold............         100         100         100  not applicable......  100
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Source: FAA Emissions Dispersion Modeling System version 4.4.


                                    Table 4.--Comparison of Proposed Action Emissions to the SIP Regional Inventories
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                                                                                                                                              Is the
                                                                                               Daily       Original SIP         SIP          proposed
            Pollutants of concern                                Units                    emissions from    maintenance     maintenance       action
                                                                                             proposed          plan         plan update     regionally
                                                                                              action                                       significant?
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CO...........................................  (tons/day)...............................           0.732      1,125.4 to      1,736.9 to             No.
                                                                                                                 1,203.3         1,864.9
PM10.........................................  (tons/winter day)........................           0.007    66.9 to 95.6   62.3 to 107.5             No.
VOC..........................................  (tons/summer day)........................           0.065      459 to 507              NA             No.
NOX..........................................  (tons/summer day)........................           0.559      308 to 332        303.3 to            No.
                                                                                                                                  353.3*
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* Updated regional NOX values were listed in the PM10 Maintenance Plan Update.

General Conformity Determination

    Under the General Conformity regulations, the FAA can utilize a 
number of criteria for demonstrating conformity with SIPs. For this 
determination, the FAA believes it is appropriate to utilize the 
criterion of demonstrating that emissions for the Proposed Action are 
specifically identified and accounted for in the SIP maintenance plans 
under 40 CFR 93.158(a)(1). The FAA has reviewed specific SIP 
maintenance plan documentation to affirm that the City and County of 
Denver's airport emissions inventory for DEN was included in the SIP 
maintenance plans by the State and regional air quality agencies. In a 
letter dated April 5, 2006, the Colorado Department of Public Health 
and Environment confirmed the emissions associated with the Proposed 
Action are reasonably accounted for in the Colorado SIPs. The FAA 
recognized that the SIP maintenance plans for the DMA include the 
future aviation activity levels predicted for the airport. The aircraft 
emissions included in the Technical Support Documents for the 2000 CO 
Maintenance Plan, the 2001 PM10 Maintenance Plan, the 2001 
1-hour Ozone Maintenance Plan, and the 2004 8-hour Ozone Action Plan 
all rely on a Colorado Department of Aviation's aviation activity 
forecast that was prepared in 1999. From the forecasted activity 
levels, emissions were calculated and properly collaborated with the 
Colorado Department of Public Health and Environment for inclusion in 
the budgets listed in DMA's SIP maintenance plans.
    Figure 1 provides the historical aircraft activity and future 
levels used to predict SIP emissions for future milestone maintenance 
years. Note that the future aircraft activity levels for DEN are 
extrapolated based on historical levels plus the addition of 
Southwest's proposed activity. The resulting aircraft activity levels 
are extrapolated forward to illustrate how the influence of the 
Proposed Action compares to the future aircraft activity represented in 
the SIP maintenance plans.
    The addition of Southwest's increased aircraft activity levels 
directly affects the air carrier category at DEN. To better illustrate 
the influence Southwest will have on this category as it was 
represented in the SIP maintenance plans, Figure 2 isolates the air 
carrier category. The additional operations have been added to the 
actual trend line and compared to the future air carrier activity 
levels for future milestone years to demonstrate that the expected 
levels of operations are still below the air carrier aircraft activity 
levels represented in the SIP maintenance plans.
    The FAA demonstrates that the total of the actual aircraft 
operations plus the proposed aircraft operations and associated 
emissions for Southwest is below the SIP's forecasted values, and 
therefore emissions attributed to flights by Southwest are already 
accounted for in the SIP emissions inventories. The FAA believes, and 
State representatives confirmed, that the total net emissions 
associated with the Proposed Action (including the aircraft emissions) 
are reasonably accounted for in the SIP maintenance plans. As a result, 
the Proposed Action demonstrates a conformance to the existing and 
updated SIP maintenance plans for the DMA.

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References

    40 CFR part 93 subpart B--Determining Conformity of General 
Federal Actions to State or Federal Implementation Plans.
    EPA and FAA, General Conformity Guidance for Airports Questions 
and Answers, September 25, 2002.

Carbon Monoxide References

    Colorado Department of Public Health & Environment, Air 
Pollution Control Division, Technical Support Document: Carbon 
Monoxide Redesignation Request and Maintenance Plan for the Denver 
Metropolitan Area, January 4, 2000.
    Colorado Department of Public Health & Environment, Air 
Pollution Control Division, Carbon Monoxide Redesignation Request 
and Maintenance Plan for the Denver Metropolitan Area, January 10, 
2000.
    Colorado Department of Public Health & Environment, Air 
Pollution Control Division, Technical Support Document: Carbon 
Monoxide Maintenance Plan Revision for the Denver-Boulder Attainment 
Area, June 2003.
    Colorado Department of Public Health & Environment, Air 
Pollution Control Division, Carbon Monoxide Maintenance Plan for the 
Denver Metropolitan Area, June 19, 2003.
    Colorado Department of Public Health & Environment, Air 
Pollution Control Division, Technical Support Document: Carbon 
Monoxide Maintenance Plan Revision for the Denver-Boulder Attainment 
Area, September 2005.
    Colorado Department of Public Health & Environment, Air 
Pollution Control Division, Carbon Monoxide Maintenance Plan for the 
Denver Metropolitan Area, December 15, 2005.

PM10 References

    Colorado Department of Public Health & Environment, Air 
Pollution Control Division, Technical Support Document: Colorado 
State Implementation Plan for PM10, Denver Metropolitan 
Nonattainment Area, Emissions Inventories and Dispersion Model 
Results for the Maintenance Plan, Adopted April 19, 2001.
    Colorado Department of Public Health & Environment, Air 
Pollution Control Division, PM10 Redesignation Request 
and Maintenance Plan for the Denver Metropolitan Area, Adopted April 
19, 2001.
    Colorado Department of Public Health & Environment, Air 
Pollution Control Division, Revised Technical Support Document: 
Colorado State Implementation Plan for PM10, Denver 
Metropolitan Nonattainment Area, Emissions Inventories and 
Dispersion Model Results for the Maintenance Plan, September, 2005.
    Colorado Department of Public Health & Environment, Air 
Pollution Control Division, PM10 Maintenance Plan for the 
Denver Metropolitan Area, Approved by the Colorado Air Quality 
Control Commission December 15, 2005.

Ozone References

    Colorado Department of Public Health & Environment, Air 
Pollution Control Division, Technical Support Document: Colorado 
State Implementation Plan for Ozone, Denver Metropolitan 
Nonattainment Area, Emissions Inventories for the Maintenance Plan 
and Redesignation Request, Adopted January 11, 2001.
    Colorado Department of Public Health & Environment, Air 
Pollution Control Division, Ozone Redesignation Request and 
Maintenance Plan for the Denver Metropolitan Area, Adopted January 
11, 2001.
    Colorado Department of Public Health & Environment, Air 
Pollution Control Division, Technical Support Document: Colorado 
State Implementation Plan for Ozone, Denver Metropolitan 
Nonattainment Area, Appendix C--Emissions Inventories for the Ozone 
State Implementation Plan, February 26, 2004.
    Federal Register, USEPA approval of DMA's Ozone Action Plan, May 
17, 2005.

    Issued in Washington, DC, on April 20, 2006.
John M. Allen,
Deputy Director, Flight Standards Service.
[FR Doc. 06-3998 Filed 4-26-06; 8:45 am]
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