Transcript Slide 1

Anchorage CO
Maintenance Plan
(SIP) Revisions
Presentation to the
AMATS Air Quality Advisory Committee
February 19, 2008
Anchorage Assembly voted
discontinue I/M on or before
December 31, 2009
• Current SIP commits to continued operation of
the I/M Program.
• Before I/M can be lawfully discontinued, SIP
must be revised to show that Anchorage will
continue to comply with CO air quality standards
without I/M.
• EPA must approve changes to SIP.
Anchorage CO Maintenance Plan / SIP
Development Schedule
Begin preparation of CO emission inventory and analysis of probability of
compliance with NAAQS
11/01/07
Complete preliminary review with EPA and ADEC of CO inventory and
analysis of probability of compliance.
2/15/08
Meet with AMATS Air Quality Advisory Committee to review and discuss
CO emission inventory and analysis of probability of compliance
2/19/08
Status report to AMATS TAC
2/28/08
Status report to AMATS Policy Committee
3/13/08
Meet with AMATS Air Quality Advisory Committee to present staff
recommendations on CO control measures in Plan. Which primary and
contingency measures should be included in the Plan?
3/17/08
Staff completes draft CO Maintenance Plan / SIP revisions
4/11/08
Meet with AMATS Air Quality Advisory Committee to review draft CO
SIP/Maintenance Plan and prepare final recommendations for
consideration by AMATS TAC and Policy Committees.
4/21/08
AMATS TAC meets to review draft CO SIP/Maintenance Plan and prepare
recommendations for consideration by Policy Committee.
4/24/08
AMATS Policy Committee considers approval of CO SIP/Maintenance
Plan.
(If approved, Plan is forwarded to Anchorage Assembly.)
5/08/08
Steps in preparation of a revised
CO Maintenance Plan (SIP)
 1. Prepare new CO emission inventory and
emission projections thru 2023
 2. Estimate probability of continued compliance with
CO air quality standards given expected changes
in emission rates
3. Decide which CO control measures should be
included in the plan.
4. Identify contingency measures should a violation
of the air quality standard occur
5. Prepare a “CO emission budget” for determining
conformity between future transportation plans
and air quality goals outlined in the SIP
Anchorage CO
Emission Inventory
CO emission inventory and
emission projections 2007-2023
• Used recommended models from EPA or
FAA to estimate CO emission rates
– Motor vehicles
– Aircraft
– Nonroad
– Area sources
– Point source
MOBILE6
EDMS
NONROAD
AP-42
ADEC permit info
Current and future CO emission estimates
were based in part on:
• Transportation model projections of vehicle travel activity
(miles traveled per day, number of starts)
• Current aircraft operations based on counts, future
growth based on Airport Master Plan projections
• Fireplace and wood stove use estimated with telephone
survey data.
• ISER forecasts of growth in population, households, and
employment were used to help predict CO emissions
through 2023.
Assume that I/M will end
December 2009
CO Emission
Inventory for
Anchorage
Bowl
Estimated Anchorage Bowl CO Emissions in 2007
miscellaneous
9.0%
fireplaces &
woodstoves
6.2%
point sources
1.3%
rail & marine
0.2%
aircraft
13.0%
natural gas heating
3.8%
Total CO Emissions = 100.7 tpd
motor vehicles
66.5%
Projected Area-wide CO Emissions in Anchorage (2007-2023)
120.0
CO Emissions (tons per day)
100.0
80.0
60.0
other (nonroad, rail, marine)
point sources
40.0
space heating
fireplaces and woodstoves
20.0
aircraft
motor vehicles
0.0
2007
2009
2011
2013
2015
2017
2019
2021
2023
CO emission
inventory for the
area surrounding
the Turnagain
monitoring
Station.
The Turnagain
station measures
the highest CO
concentrations in
Anchorage
CO emissions in
the Turnagain
area are among
the highest in the
bowl.
Estimated CO Emissions in Turnagain Area (2007)
miscellaneous
12%
Space heating –
natural gas
5%
fireplaces and
wood stoves
10%
CO emissions in
Turnagain area = 5.99 tpd
motor vehicles
73%
Projected CO Emissions Turnagain Area (2007-2023)
7.0
CO emissions (tons per day)
6.0
5.0
4.0
3.0
miscellaneous
natural gas heating
2.0
fireplaces & wood stoves
motor vehicles
1.0
0.0
2007
2009
2011
2013
2015
2017
2019
2021
2023
Estimate Probability of
Compliance with CO
Air Quality Standard
2007-2023
The EPA has recommended using a
probabilistic approach to assessing long term
compliance with the federal CO standard.
• Need 90% or greater probability of compliance
• Use statistical techniques (linear regression and
prediction interval) to analyze monitoring data and
compute probability of compliance
• Project probability of compliance in future years based
on projected CO emission trend
Compliance is determined by the
magnitude of the 2nd highest
8-hour concentration measured
each year
Second maximum
8-hour average concentration < 9 ppm
Prediction Interval - In regression analysis, a range of values that
estimate the value of the dependent variable for given values of one or
more independent variables.
where
yp
=
yh
+
t(; n-2) . s{pred}
This is a one-sided prediction interval because we are
interested only in the upper range of values for the
dependent variable
90th Percentile Prediction Interval Computed from
Turnagain 2nd Maximum
The probability of complying with the standard at
2007 emission levels is estimated to be 98.1%.
The probability of complying with the standard
in a future year can be estimated based on
whether emissions are projected to increase
or decrease relative to 2007.
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%
What if we have underestimated the
impact of discontinuing I/M?
What if vehicle travel and wood
heating grow faster than anticipated?
How sensitive are our projected probabilities
of compliance to changes in initial
assumptions about future CO emissions ?
Comparison of Original Assumptions used in
Maintenance Demonstration with
those used in Sensitivity Analysis
Original Assumptions
used in Maintenance
Demonstration and
Probability
Computations
Revised “Worst Case”
Assumptions Used in
Sensitivity Analysis
Discontinuation
of I/M
Motor vehicle emissions
increase by roughly 20%
Motor vehicle emissions
increase by roughly 40%
Growth in VMT
and Vehicle
Starts and Idling
4% increase between 2007
and 2023
12% increase between 2007
and 2023
Fireplace and
Woodstove Use
No change in wood burning
rates per household between
2007-2023
2% growth in wood heating
per year
Comparison of Sensitivity Analysis Assumptions with
Original Emission Projections
8.0
"extra" emissions assumed in
sensitivity analysis
7.0
6.0
CO emissions (tpd)
In this sensitivity
analysis, by
2023, assumed
CO emissions
are 23% higher
than the original
projections
5.0
original CO emission
projection
4.0
3.0
2.0
extra emissions due to increased wood heating
extra emissions from growth in vehicle travel
1.0
0.0
2007
extra emissions assumed from termination of I/M
2009
2011
2013
2015
2017
2019
2021
2023
Even using “worst case” assumptions in sensitivity analysis,
the probability of complying with the CO standard is well
above 90% every year.
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
Original emission projections
98.1%
98.8%
99.2%
99.0%
98.4%
98.8%
99.1%
99.1%
99.2%
99.2%
99.3%
99.4%
99.4%
99.5%
99.5%
99.6%
99.6%
“Worst Case” analysis
98.1%
98.7%
99.1%
97.8%
94.7%
95.3%
95.8%
96.2%
96.5%
96.8%
97.1%
97.5%
97.7%
97.8%
98.0%
98.0%
98.1%