8HR EAC Ozone Projects and DRAFT Modeling Guidance Status

1
8-HR EAC Ozone Projects and DRAFT Modeling
Guidance Status

• Erik Snyder
• U.S. EPA Region 6
• Oklahoma EAC Technical Meeting March 5, 2003

2
(No Transcript)
3
8 Hour Ozone TIMELINE
10/15/03 EPA provide comments to State
Finalize 8hr implementation Rule
7/15/03 State Designation Recommendation Due
4/07 8-hr SIPs due
4/15/04 EPA designation
1/03
1/05
1/04
1/06
1/07
12/31/02 Early Action Compacts (EAC) due
3/31/04 Local EAC plan due to States
EAC Attainment Date
12/31/04 EAC SIPs due
6/16/03 Initial List of Local Control Measures due
4
Early Action Compact 8-hr Ozone Projects in
Region 6

• Oklahoma (OKC and Tulsa Areas)
• Texas (Austin/San Marcos, Northeast Texas, and
  San Antonio Areas)
• New Mexico (San Juan County)
• Louisiana (Shreveport-Bossier City Area)
• Arkansas (West Memphis Area)
• For a list of all compacts go to
• http//www.epa.gov/ttn/naaqs/ozone/ozonetech/
  (Scroll down to G.8. H)

5
(No Transcript)
6
Summary of DRAFT 8-Hour Modeling Guidance

• Draft was proposed in May 1999 and is currently
  being updated. Living document and may be revised
  as needed and posted on EPAs website
  http//www.epa.gov/ttn/scram/).
• Purpose of the document Recommend procedures
  for estimating if a control strategy to reduce
  emission will lead to attainment of the 8-hour
  NAAQS for ozone.
• Part I How to apply results to demonstrate
  attainment.
• Part II How to setup and apply models.

7
Part II - How do I apply air quality models?

• Develop conceptual description of the problem.
• Develop modeling/analysis protocol.
• Select appropriate model and time periods to
  model.
• Choose geographic area and horizontal/vertical
  resolution.
• Generate meteorology, emissions, and air quality
  inputs.
• Evaluate performance and perform diagnostic
  tests.
• Project future emissions and simulate control
  strategies.

8
Part I - How do I use results from models and
other analyses to help demonstrate attainment?

• Modeled attainment test.
• Screening test.
• Weight of evidence determination.
• Documentation accompanying attainment
  demonstration.

9
What is the modeled attainment test?

• Uses model results in a relative sense.
• Steps -.
• Compute site specific observed design value.
• Estimate site specific modeled relative reduction
  factor.
• Multiply reduction factor in step 2 by design
  value in step1 to get future design value.
• Repeat steps 1-3 for each monitor site where
  current design value is gt84ppb.
• If all predicted future design values are lt84
  ppb, modeled attainment test is passed.

10
Example of RRF calculation From 1999 DRAFT
Guidance

• Table 3.4 Example Calculation of a Site-specific
  Future Design Value (DVF)f

11
What is the screening test?

• Predicts future air quality where there are no
  nearby monitors.
• Applies to areas where predicted 8-hour max. is
  consistently greater than prediction in vicinity
  of monitors.
• Steps multiply location specific relative
  reduction factor times the areawide current
  design value to get future design value.
• If predicted future design value is lt84 ppb,
  screening test is passed.

12
What is a weight of evidence determination?

• Recommends consideration of other analyses in
  concert with modeled attainment test and
  screening test results.
• Recommended core analyses
• Other air quality model predictions such as
  reduction in grid-cells hours gtNAAQS.
• Analysis of air quality and emissions trends.
• Observational models such as source apportionment.

13
What is a weight of evidence determination?(concl
uded)

• May include other optional analyses when the
  following is provided .
• Rationale for the analysis.
• Identify data bases.
• Describe methodology applied.
• Identify outcomes consistent with hypothesis.
• Guidance recommends subsequent reviews and
  integration with PM2.5 and visibility plans.

14
RECAP - What are major components of attainment
demonstrations?

• Technical analyses to locate and identify sources
  of emissions that are causing violations of the
  8-hour NAAQS within the vicinity and immediately
  downwind of nonattainment areas,
• Technical analyses to assess and identify
  controls to eliminate significant contribution
  to other nonattainment areas,
• List of adopted measures with schedule for
  implementation,
• Commitment to perform a mid-course review
  (non-EAC), and.
• Contingency measures.

15
RECAP - General guidance for attainment
demonstrations

• Must be based on photochemical grid modeling or
  any other analytical method determined by the
  Administrator
• Model should meet several general criteria - Part
  51, Appendix W (i.e., EPAs Guideline on Air
  Quality Models) proposed in 2000
• DRAFT Guidance on the use of models and other
  analyses in attainment demonstrations for the
  8-hour ozone NAAQS scheduled to go final with
  8-hour ozone NAAQS implementation rule (Dec. 2003
  timeframe)

16
Status of DRAFT guidance

• Living document and may be revised as needed and
  posted on EPAs website http//www.epa.gov/ttn/scr
  am/).
• Seeking comments on potential changes -
• Which future year of emission estimates to model,
  
• Recommendation to model longer time periods, up
  to full ozone season, and
• Use of spatial fields of ambient concentrations
  as part of the modeled attainment test.

17
(1) Future year for modeling

• Three years of data used to determine whether or
  not area is attaining.
• OPTIONS - attainment year or first year of three
  year period.
• Factors to consider
• using a single year (or ozone season) to estimate
  future ozone concentrations when the design value
  is a three year average,
• implementing rules on a schedule that provides
  for attainment by the attainment year, and
• emissions growth out to the attainment year.
• In either case emissions for three year period is
  needed to either guarantee attainment, or provide
  support for 1 year extensions.

18
(2) Length of time period to model

• Recent scientific review .
• Models do better job of replicating general
  temporal/spatial patterns than specific
  concentrations at given times and locations.
• Suggests improved model performance with longer
  time scales on the order of full synoptic cycle
  (e.g., 10-21 days).
• Guidance recommends averaging concentrations
  across several days (apply a relative test
  rather than absolute test).
• Modeling longer time periods is more technically
  robust, and more resource intensive.
• Model synoptic cycle or summer season, not 10
  discrete days.

19
(3) Spatial Analysis

• Data (e.g. modeled/ambient concentrations, etc.)
  can be spatially interpolated to provide
  estimates over a broad area including area where
  no monitors or data exist
• Spatial interpolation is the procedure for
  estimating the value of properties at unsampled
  sites within an area covered by existing
  observations
• Uses statistical techniques (e.g., kriging) to
  develop spatial displays of air quality

20
(3) Use of spatial fields in modeled attainment
test

• Recent studies - spatial correlation structure of
  ozone (mostly due to meteorology) is stable
  enough to allow accurate ozone predictions up to
  600 km from monitor.
• Statistical methods provide estimate of
  uncertainty - estimate probability that future
  predicted field lt of NAAQS.
• Test provides complete spatial picture of
  attainment.
• EPA preparing guidance on spatial field
  development and using spatial fields to assess
  the monitoring network.
• Retain attainment test at monitors, replace
  screening test with spatial fields test.

21
Current Status of 8-hr Modeling Guidance

• December 2002 to January 2003 - Comments
  received from State/Locals on the possible
  changes to the 8-hour draft ozone modeling
  guidance.
• Comments are currently being reviewed by OAQPS
  and Regional Offices.
• Updated draft by May/June 2003.
• Final by end of year.

22
Additional Recent 8-hr Guidance

• November 18 2002, base year EI memorandum.
• 2002 is the base year EI for 8-hr ozone, PM2.5
  and Regional Haze SIPs.
• 2002 EI used for reasonable further progress
  (RFP) and rate of progress (ROP).
• Modeling (developed from voluntary 8-hr ozone
  modeling projects) based on previous base years
  and for each set of meteorological episode
  conditions may be used in SIP submittals if still
  applicable for an attainment demonstration.
• 2002 EI needs to be factored into the analysis
  (i.e., current emissions in RRF analysis).

23
Additional Recent 8-hr Guidance (cont.)

• February 27, 2003, extension of deadline for
  State/Tribal submission of 8-hr recommendations
  from 4/15/2003 to 7/15/2003.
• Extension granted to allow States/Tribes to allow
  additional time to engage stakeholders and allow
  them to consider EPAs proposed 8-hour ozone
  implementation regulation, which EPA expects to
  issue in March 2003.
• EPA currently anticipates the (Nov. 2002) DRAFT
  consent decree will be finalized and that it will
  require EPA to designate areas no later than
  April 15, 2004.

24
Additional Guidance Forthcoming

• Developing Mid-Course Review Guidance for 8 hr
  (non-EAC).
• Preparing white papers.
• Multi-pollutant modeling.
• Assessing transport or significant
  contribution.
• Return to EAC Home Page