August 10, 2011

MEMORANDUM

SUBJECT: Technical Support Document (TSD): Technical Review of 2010 and 2009 submittals to Alaska Statewide SIP and the Anchorage Carbon Monoxide
Maintenance Plan

FROM: Krishna Viswanathan Environmental Engineer

Claudia Vaupel Environmental Protection Specialist

TO: EPA Docket EPA-R10-OAR-2010-0917

I. PURPOSE

This TSD presents our review of the revisions to the Alaska State Ca rbon Monoxide (CO) State Implementation Plan (SIP) submitted to EPA in 2010 and 2009. It documents our conclusion that the 2010 revision meets the requirements of the Clean Air Act (CAA or the Act). Although we
reviewed the 2009 submittal in s upport of our technica l analysis, we are not taking action to approve its provisions because the 2010 submittal supersedes the 2009 revision.

II. BACKGROUND

A. Anchorage maintenance area planning history

Anchorage, Alaska, was first declared a nonattainm ent area for CO and classified as moderate on January 27, 1978. The Municipality of Anchorage (MOA) prepared a plan to attain the CO National Ambient Air Quality Standard (NAAQS) 1 by December 31, 1987; however, Anchorage failed to achieve attainment by December 31, 1987. The CAA was amended in November 1990, and EPA designated Anchorage as a moderate nonattainment area for CO and required submission of a revised air quality plan to bring Anchorage into attainment by December 31, 1995. EPA approved the plan in 1995, however, two violations of the NAAQS in 1996 resulted in EPA reclassifying Anchorage to serious nona ttainment on July 13, 1998, with an attainment date of December 31, 2000.

1 The national 8-hour CO ambient standard is attained when the highest 8-hour CO concentration of 9 parts per million (ppm) is exceeded no more than one time in a calendar year. EPA has pro posed to retain the current standard of 9 ppm, based on the latest review of the CO NAAQS (76 FR 8158, February 11, 2011).2 The Alaska Department of Envi ronmental conservation (ADEC or the State) submitted a new plan on January 4, 2002, and EPA proposed approva l of the plan (67 FR 38218) on June 3, 2002. On September 18, 2002, EPA approved the Anchor age CO attainment plan (67 FR 58711).

The State submitted a maintenance plan and a redesignation request for the Anchorage CO nonattainment area on February 18, 2004. EPA proposed approval of the Anchorage CO maintenance plan on May 10, 2004 (69 FR 25869) and approved the plan on June 23, 2004 (69 FR 34935). The maintenance plan relied on control strategies needed to assure maintenance of the CO NAAQS. The strategy focused on the Fede ral Motor Vehicle Emission Control Program, an I/M program, expanded wintertime transit serv ice and promotion of engine pre-heaters.

On March 29, 2002, and December 11, 2006, the State submitted revisions to the CO SIP. The 2002 submittal revised the statewide I/M regulations to provide for electr onic vehicle inspection renewal and to remove the requirement for a pape r certificate to be maintained in the vehicle.
The 2006 submittal revised the stat ewide I/M regulations to le ngthen the time period before which new vehicles are required to obtain their fi rst certificate of inspec tion from two years to four years. Each of the submittals also contai ned minor revisions that were administrative in nature. On September 15, 2009, EPA proposed to approve the State’s submittals (74 FR 47154) and finalized the approval on April 21, 2010 (75 FR 13436).

B. What changes to the Alaska SIP were submitted for EPA approval?

The State has submitted two revisions to the Anchorage CO maintenance plan. The contents of
the submittals are listed below and described in more detail with analysis in the sections of this
TSD that follow.

November 13, 2009 Submittal (2009 submittal):

1) Alaska Administrative Code, Title 18, Chapte r 50 Air Quality Control, and Chapter 52 Emissions Inspection and Maintenance Requi rements for Motor Vehicles, with an effective date of November 4, 2009.

2) Amended sections of the State Air Quality Control Plan , adopted by reference under 18 AAC 50.030, August 5, 2009, including:

a. Volume II. Section II: Ai r Quality Control Program
b. Volume II. Section III.A: Statewid e Carbon Monoxide Control Program

c. Volume II. Section III.B: Anchorag e Transportation Control Program
d. Volume III. Appendices to Volume II (includes 18 AAC 50 regulations, Anchorage emission inventory, Anchorage analysis for complying with the NAAQS for CO, and Anchorage I/M ordinances and code)

The 2009 submittal contains a significant revision to the Anchorage CO maintenance plan that lengthens the grace period for new vehicles to obta in the first certificate of inspection from four years to six years and exempts certain types of vehicles from the I/M program. The 20093 submittal updates the CO contingency measures and includes an updated 2007-2023 emissions inventory and motor vehicle emission budget.

September 29, 2010 Submitta l (2010 submittal):

1) Alaska Administrative Code, Title 18, Chapter 50 Air Quality Contro l with an effective date of October 29, 2010.

2) Sections of the State Air Quality Control Plan , adopted by reference under 18 AAC 50.030 as amended August 20, 2010, including:

a. Volume II. Section II: Ai r Quality Control Program
b. Volume II. Section III.A: Statewid e Carbon Monoxide Control Program

c. Volume II. Section III.B: Anchorag e Transportation Control Program
d. Volume III. Appendices to Volume II (includes 18 AAC 50 regulations)

The 2010 submittal supersedes the 2009 submittal w ith a significant revision to the Anchorage CO maintenance plan that will remove the I/M program as an active control measure in the SIP upon final approval of this revision by EP A. The 2010 submittal updates the 2007-2023 emissions inventory to account for the remova l of the I/M program after 2011 and includes a revised the motor vehicle emissions budget. The submittal moves the I/M program as an active
control measure in the SIP and sh ifts it to a contingency measure that can be implemented should
a violation of the CO standard occur. The 2010 submittal also includes the contingency measures that were updated in the 2009 submittal.

III. REVIEW OF SUBMITTALS

A. What SIP revisions is EPA reviewing in this TSD?

This TSD evaluates the 2010 submittal. Technical information from the 2009 submittal was used only to substantiate the revi ew of the 2010 submittal.

B. Clean Air Act basis for review

EPA proposed approval of the Anchorage CO maintenance plan on May 10, 2004 (69 FR 25869) and approved the plan on June 23, 2004 (69 FR 34935). The maintenance plan relies on control strategies needed to assure maintenance of the NAAQS for CO. As stated earlier in this document, one of the primary control measures is an I/M program. The I/M program may be
revised or removed as an active control measure in the SIP, provided the State can satisfy the requirements of CAA secti on 110(l), which states:

Each revision to an implementation plan submitted by a State under this Act shall be adopted by such State after reas onable notice and public hearing. The Administrator shall not approve a revision to a plan if the revision would interfere with any applicable requirement concer ning attainment and reasonable further4 progress (as defined in secti on 171), or any other appli cable requirement of this
Act.

A demonstration is necessary to show that the State’s proposed revisions will not interfere with attainment or maintenance of any NAAQS, and any other applicable requir ement of the Act. In addition, although EPA may approve removal of a control measure with such a demonstration, any measure that is removed from the active porti on of a SIP must be retained as a contingency measure under section 175A(d) of the Act. 2

C. EPA’s review of the State’s analysis demonstrating continued maintenance of the
carbon monoxide standard

Because the 2010 submittal supersedes the 2009 s ubmittal, EPA’s review focuses on evaluating the removal of the I/M program as an active c ontrol measure in the 2010 submittal. However, we
reviewed the maintenance demonstration in the 2009 submittal and considered it in our analysis. The 2009 review provided technical information that enabled comparability of the two I/M options, the 6 year new car exemption and removal of the I/M program. This supporting technical comparison provided EPA with additio nal confidence that the State submission was technically robust.

All of the technical work contained in the State’s submittal was performed using similar methodology that the State used to demonstrate maintenance in the Anchorage maintenance plan that EPA approved in 2004. Where data was avai lable, emissions invent ory and modeling inputs were updated with more recent information. This is explained further in our review and analysis
of the State’s submittal below.

1. Emissions inventory: area-w ide and Turnagain micro-inventory

The State submitted an updated emissions inventory for the period 2007-2023. The inventory was prepared in accordance with EPA’s CO emissions inventory guidance. 3 The inventory included emissions for stationary sources, area sources, non-road mobile sources and on-road mobile sources on a typical 24-hour winter day. The State prepared an area-wide inventory of the Anchorage maintenance area and a micro-inve ntory of the area surrounding the Turnagain monitoring station in west Anchorage. The Turnagain station exhibits the highest CO concentrations of the current monitoring networ k; it has been shown to be approximately 20% higher than the next highest site. The Turnagain micro-inventory provides added insight into the sources of CO surrounding the monitor and guided th e state in developing c ontrol strategies for the Anchorage maintenance area. The complete i nventory is included in the Appendix to Section
III.B.3 of the State’s submittal.

Area-wide emissions inventory

2 See September 4, 1992 memorandum from John Calcagni to the EPA Air Division Directors (``Procedures for Processing Requests to Redesignate Area s to Attainment,'' Memorandum from John Calcagni, Director, Air Quality Management Division).

3 Emissions Inventory Requirements for Carbon Monoxide State Implementation Plans EPA-450/4-91-0115 The State projected the area-wide and Turnagain inventories from the 2007 base year inventory to the years 2008-2023. In the 2010 submittal, the area -wide inventory depicts elimination of the I/M program starting in 2011. EPA has reviewed these projections and summarized them in
Table 1.

Table 1. Anchorage Area Wide Projected CO Emissions: To ns per Day (tpd)

2007 Base Year with I/M program
in effect in 2007 2023 Horizon Year
with no I/M

program
Source Category CO
Emitted % of
total CO
Emitted % of
total
Motor Vehicles 67.4 66.7% 55.7 57.1%
Aircraft – Ted Stevens International and Merill Field Airport Operations 13.1 12.9% 19.0 19.5%

Woodburning-fireplaces and
woodstoves 6.2 6.2% 7.0 7.1%

Space Heating-natural gas 3.8 3.7% 4.1 4.2% Miscellaneous-snowmobiles, snow removal, welding, rail, marine, etc) 9.3 9.2% 10.2 10.4%

Point Sources (power generators, sewage sludge, incineration) 1.3 1.3% 1.4 1.4%

Total 101 100% 97.5 100%

Without an I/M program, total area-wide CO emissions are projected to decline by 3.5 tpd (3.5%) between the 2007 base year (101 tpd) a nd the 2023 horizon planning year (97.5 tpd). This is caused by a 16% reduction in on-road emi ssions (from 51.04 tpd to 42.85 tpd) during this timeframe. The primary driver of lower on-road emissions is a su stained reduction in average inuse emission rates, as newer, cleaner vehicles co ntinue to replace older, higher emitting vehicles.

Projections from the area-wide emissions inventor y indicate that CO emissions reductions from 2007-2023 are expected to occur in Anchorage either with or without the I/M program in place. If the I/M program is removed as an active cont rol measure in the Anchorage SIP, it must be retained as one of the plan’s contingency measur es that can be implemented should a violation of
the CO standard occur.

Turnagain micro-inventory The Turnagain micro-inventory represents th e area near the Turnagain monitoring station, located in the Spenard-area nei ghborhood, which the State has iden tified as having the highest
CO concentrations of all the m onitoring stations in Anchorage. Maximum 8-hour concentrations were typically 10 to 20% higher than the next hi ghest site called Garden in east Anchorage. During the 1997-98 CO Saturation Study 8-hour CO concentrations at Turnagain were the highest among the 20 sites include d in the study. The state provided support to establish that the probability of exceeding the national ambient air quality standard at Turnagain at current CO emission levels is about 1 in 100 while the probabili ty of violating at the Garden station is less than 1 in 1,000. For this reason, the State prepared a micro-inve ntory of the area surrounding the Turnagain monitoring site for the maintenan ce demonstration. In order to perform this6 demonstration, CO emissions were estimated from the 2007 base year and projected through
2023. Table 2 shows the State’s em ission inventory projections. Emissions are projected to decrease by about 12% in the Turnagain micro- inventory area without an I/M program. The micro-inventory trends are consiste nt with the area-wide trends.

Table 2. Turnagain Micro-emissions inventory: Tons per Day (tpd)

2007 Base Year with I/M program in
effect in 2007 2023 Horizon Year
with no I/M

Source Category CO
Emitted % of total CO
Estimated % of total

Motor Vehicles 4.42 73.4% 3.59 67.8%
Air Craft – Ted Stevens International and Merill Field Airport Operations -- --% -- --%

Woodburning-fireplaces and
woodstoves 0.62 10.3% 0.67 12.6%

Space Heating-natural gas 0.28 4.6% 0.29 5.5% Miscellaneous-snowmobiles, snow removal, welding, rail, marine, etc) 0.70 11.7% 0.73 13.8%

Point Sources (power generators, sewage sludge, incineration) -- -- -- --

Total 6.01 100% 5.29 100%

2. Maintenance demonstration with pr obabilistic rollforward modeling

Because the Turnagain monitoring site exhibits th e highest CO concentra tions in the monitoring network, the State used the micro-inventory from the Turnagain area in the maintenance
demonstrations. After discussions with the EPA Regional Office, the State used a probabilistic roll-forward approach to demons trate maintenance with the CO standard. A detailed discussion of this methodology and results can be found in the Appendix to Section III.B.6 of the State’s
submittal. Below is a brief overview of the methodology and the results of the methodology which are largely comprised of excerpts from Vo l. II Section III.B and the Appendix to Section
III.B.6.

The results of the probabilistic rollforward mo deling in the submittals demonstrate that the Anchorage area will continue to attain the CO standard through the year 2023 without the I/M program in place.

Rollforward modeling is a simple calculation th at assumes that the pe rcentage reduction in ambient CO design values (maximum regulatory valu es recorded during the period of interest) to the level of the ambient standard is directly pr oportional to the percenta ge reduction in emissions
needed to demonstrate attainment of that standard or the increase in emissions that can occur and still demonstrate attainment (allowable emissions). The probabilistic roll-forward procedure is7 described in detail in the Vol. II Section III.B .6 of the state’s submissions. The results are as
follows:

1. The computed 2007 Design Value from the Turnagain monitor is 7.23 ppm.
2. Total 2007 CO emissions for the Turn again micro-invent ory area is 6.01 tpd. 3. The allowable percentage emission increase from 2007 levels in the Turnagain area is
24.5%. 4. The allowable emissions increase is 7.48 tpd. 5. The theoretical probability of maintaining compliance wi th the CO NAAQS is greater than 90% provided emissions remain below th e allowable emissions level identified in step 4.

Figure 1. Probability of Compliance with Allowable Emissions with no I/M program

The composite modeling results as shown in th e figure above indicate that the projected emissions remain consistently below the allowabl e emissions levels and show a decreasing trend through the projection horizon desp ite an increase in emissions in 2011 consistent with the termination of the I/M program.

The State prepared an additional sensitivity anal ysis to verify the robustness of the method against assumptions that represen ted a worst-case scenario. The state re-estimated CO for the 2008-2023 period with the assumptions that:

1) the growth in vehicle travel in the Turnag ain area will be three times greater than projected (vehicle travel would increase by 12% between 2007 and 2023 instead of the 4% assumed); 2) there will be a 2% per an num growth in wood heating among households in the Turnagain area resulting from high natural gas prices.

The State’s sensitivity analysis shows that even with the assumed higher rates of growth in vehicle travel and wood burning, the probability of compliance remains at 99% or greater each year through 2023 with or w ithout an I/M program.8 EPA’s evaluation of the proba bilistic rollforward modeling in the State’s 2010 submittal concludes that the Anchorage area will continue to attain and ma intain the CO standard through the year 2023 without the I/M program in place.

3. Contingency measures

As a primary control strategy in the Alaska SIP, the I/M program for Anchorage must be retained as a contingency measure. In addition to this contingency measure, the previously approved contingency measures in the SIP continue to apply (69 FR 25872).

As stated above, section 175A(d) of the Act requires that the St ate will implement all measures with respect to the control of the air pollutant concerned which were contained in the State implementation plan for the area before redesign ation of the area as an attainment area. To satisfy this requirement, the State will be re moving the Anchorage I/M program as a primary control measure in the SIP and shifting it to a contingency measure that will be available for implementation if needed to ensure continue d maintenance of the CO NAAQS. As documented in Volume II, Section III.B.9 of the State’s 2010 submittal, Anchorage will retain the local legal authority necessary to implement the I/M program as a contingency measure. Similarly, the State will retain its authority to implement the I/M program under state regulation, 18 AAC 52 (included in the State’s submittal in Section III. A.2), as specified in Alaska Statutes 46.14.400.

The 2009 submittal updated the contingency measures section of the Anchorage CO maintenance plan. The contingency measure identified as “transit service expa nsion through 2006” was removed from the list of contingency measur es. Projected times for implementation of contingency measures were added for each measure. The implementation times range from 6 to 24 months. The following contingency measures were added in the 2009 submittal and included
in the 2010 submittal:

 Increase public awareness and educati on, transit, carpool, and vanpool promotion
efforts.

 Curtail or limit the use of firepl aces, wood stoves and other wood burning appliances when high CO is predicted

 Promote increase in transit ridership among commuters by offering reduced fares or free transit fares for employees of co mpanies that contribute to subsidy.

4. Conformity budget

Under section 176 of the Act, tr ansportation plans, programs and projects in nonattainment or maintenance areas that are funded or approved under 23 USC or the Federal Transit Act must conform to an approved SIP. In short, a tran sportation plan is deemed to conform to the applicable SIP if the emissions resulting from im plementation of that tran sportation plan are less than or equal to the motor vehicle emission level established in the SIP for the maintenance year and other analysis year s. A motor vehicle emissions budget a pplies as a ceiling on emissions in the year for which it is defined, and for all subsequent years until another year for which a budget is defined or until a SIP revision modifies the budget. The State’s submittal establishes a9 new on-road motor vehicle emissions budget for the Anchorage area to be used for transportation conformity and regional conformity analyses.

The budget is based on the emission inventories a nd attainment projections found in the State’s submittal in Volume III. Appendix to Volume II, Section III.B.3. The State used the most recent population, employment, and land use assumptions a nd forecasts to generate the 2007 base year CO inventory and forecasts through 2023. This mo tor vehicle emissions budget applies for each of the years listed in Table 3. The values pr esented are based upon the 90% confidence level target for maintenance plans.

Table 3. Anchorage Motor Vehicle Em issions Budget: Tons per Day (tpd)

Calendar Year CO Emissions

2007 92.1

2008 91.7

2009 91.2

2010 90.8

2011 90.3

2012 89.9

2013 89.4

2014 89.0

2015 88.5

2016 88.0

2017 87.6

2018 87.0

2019 86.4

2020 85.8

2021 85.2

2022 84.6

2023 84.0

The motor vehicle emissions budget in the submitte d SIP meets the criteria contained in the conformity rule (40 CFR 93.118(e)(4)).

Once a motor vehicle emissions budget is a pproved by EPA, emissions modeled from the transportation network reflected in the Anchorage Long Range Tr ansportation Plan (LRTP) and Transportation Improvement Program (TIP) must be less than or equal to the approved motor vehicle emissions budget. For projects not from a conforming TIP, the additional emissions from the project together with the TIP emission mu st be less than or equal to the budget.10 Consistent with the previously approved main tenance plan, the on-road source budget is based
on emissions inventories and attainment thres holds calculated using a hybrid method that combined measured idle test data and pl ug-in data with outputs from MOBILE6.2. The maintenance plan sets out a means for agencies to compute emissions for use in TIP and project conformity determinations.

EPA has found that the conformity budget in the 2010 submittal meets the purpose of section 176(c)(2)(A) and meets the crite ria contained in the conformity rule 40 CFR 93.118(e)(4). Accordingly, EPA is proposing to approve the conformity budget contained in the State’s 2010
submittal.

5. EPA’s review of the State’s analysis demonstrating continued attainment and maintenance of other criteria pollutants

As discussed above, section 110(l) of the Act states that a revision to a plan cannot interfere with any applicable requirement concerning attainment and reasonable further progress (as defined in section 171), or any other applicab le requirement of the Act. Ba sed on our review of EPA’s Air Quality System database, the Anchorage CO maintenance area is well within the attainment limits for all of the criteria pollutants that are monitored in the area. 4 Based on this information, EPA concludes that removing the I/M program will not interfere with attainment or maintenance of other NAAQS in the area.

IV. CONCLUSION

The State’s forecast and analysis of motor vehicle pollutant emissions show that CO concentrations will decline substantially in Anchorage between 2008 and 2023 without the I/M program in place. The State’s 2010 submittal demonstrates that removal of the I/M program as
an active control measure will no t interfere with the maintenance of the CO or any other NAAQS in Anchorage. EPA finds that the 2010 submittal m eets the requirements of section 110(l) of the Act and proposes to approve it.

4 See air quality monitoring reports in the docket.