Anchorage CO Maintenance Plan

Proposed Revision to the State of Alaska Air Quality Control

Plan

April 2008

Municipality of AnchorageDepartment of Health and Human Services

History• EPA declared Anchorage a CO nonattainment area in

1978.• Air quality attainment plans were completed in 1982,

1992, and 2002.• Last violation of the NAAQS occurred in 1996.• EPA approved maintenance plan and designated

Anchorage as an attainment area in 2004.• In November 2007, Anchorage Assembly voted to

discontinue I/M no later than December 2009.

Draft CO Plan (Apr 08)

AMATS review AQ/TAC/Policy

AMATS-approved Plan(May08)

ADEC Public comment process

Anchorage Assembly review

ADEC considers comments, revises plan (if needed), legal review, and adoption

ADEC-revised SIP (Nov 08)

EPA review and approval12 to 18 months

AMATS-approved Planwith Assembly and public comments (July 08)

EPA - approved SIP (Dec 2009 to June 2010)

CO Plan Approval Process

What does the monitoring data tell

us?

CO monitoring has been conducted at 8 “permanent” locations and more than 25 temporary locations in the Anchorage bowl.

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CO Trend at Garden Monitoring Station

CO concentrations have fallen dramatically over the past 25 years.

The highest CO concentrations are measured in residential areas.

Looking north from Turnagain Station (32nd and Turnagain Boulevard)

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Turnagain Garden

mid-morning peak corresponds with departure of commuters from neighborhoods

CO Concentration by Time-of-Day at Turnagain and Garden Stations

Cold starts and warm-up idling are significant sources of CO in these neighborhoods.

What impact does discontinuing I/M have

on prospects for continued compliance

with the federal CO standard?

Because the Turnagain station exhibits the greatest potential for exceeding the NAAQS, its

data were analyzed to determine the probability of complying with the federal air quality standard

without I/M.

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98th percentile

Statistical analysis suggests that if CO emissions in the Turnagain area remain at 2007 levels, there is a 98% chance of meeting the federal CO standard.

98th Percentile Prediction Interval at Turnagain Station

The future probability of compliance can be estimated by forecasting CO emissions in the Turnagain

area.

The effect of terminating I/M on future CO emissions can be

estimated using the EPA MOBILE6 model.

CO emissions in the9 km2 area surrounding the Turnagain station were projected through 2023.

warm-up idle19%

on-road Travel54%

fireplaces & woodstoves

10%

space heating5%

other12%

Total CO emissions = 5.99 tons per day

CO emissions in Turnagain Area(Base Year 2007)

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miscellaneous

natural gas heating

fireplaces & wood stoves

motor vehicles

Projected CO Emissions Turnagain Area (2007-2023)CO emissions are projected to decline between 2007 and 2023.

Because emissions decline the probability of complying with the CO standard improves slightly over time.

Year TOTAL

CO EMISSIONS (tpd)Probability

of Compliance

2007 5.99 98.1%

2008 5.72 98.8%

2009 5.45 99.2%

2010 5.66 99.0%

2011 5.86 98.4%

2012 5.74 98.8%

2013 5.62 99.1%

2014 5.54 99.1%

2015 5.45 99.2%

2016 5.38 99.2%

2017 5.30 99.3%

2018 5.21 99.4%

2019 5.11 99.4%

2020 5.05 99.5%

2021 4.98 99.5%

2022 4.93 99.6%

2023 4.89 99.6%

Conclusion

Even if I/M is discontinued, the probability of complying with the CO standard is 98% or higher each year

between 2007 and 2023.

This is well above the 90% probability targeted by the EPA for maintenance

demonstrations.

What should Anchorage do to help minimize CO

emissions?

Primary measures• Air Quality Public Awareness

– Promote block heater use– Promote alternatives to SOV (walk, bike, bus, telecommute)– Encourage trip chaining– Inform public on benefits of vehicle maintenance (voluntary I/M?)

• Rideshare / Vanpool

• Transit Promotion

Contingency measuresMeasure or measures adopted will depend on

nature of CO violation

• Curtail or limit fireplace and wood stove use when high CO is predicted

• Increase public awareness and education, transit, rideshare and van pool promotion

• Offer reduced transit fares for employees of companies that contribute to subsidy

• Reinstate block heater installation subsidy

• Reinstate ethanol-blended gasoline

• Reinstate I/M

Motor vehicle emissions budget for use in

conformity analyses

Motor vehicle emissions budget is the allowable amount of CO that can be emitted by motor vehicles in the budget area.

Conformity regulations require that CO emissions from future transportation plans and programs stay below the motor vehicle emission budget.

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motor vehicle budget aircraft wood heat other space heat

Because total CO emissions must remain below 121.5 tpd, the motor vehicle budget shrinks from 87.8 tpd in 2007 to 79.7 tpd in 2023 as other sources grow.

Preliminary projections suggest that future transportation plans and programs can meet the shrinking motor vehicle budget and thus meet conformity requirements.

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Projected Actual Motor Vehicle Emissions

Motor Vehicle Emission Budget