Preliminary Mobile Source Significance Test Modeling Results

1
Preliminary Mobile Source Significance
TestModeling Results

• WRAP Regional Modeling Center (RMC)
• University of California at Riverside, CE-CERT
• ENVIRON International Corporation
• Presented at
• WRAP Initiatives Oversight Committee (IOC)
  Meeting
• October 9, 2002
• Tempe Mission Palms Hotel, Arizona

2
Section 309 SIP Modeling Elements

• Demonstrate that the SO2 Annex Milestone strategy
  is better than Command and Controls with
  Uncertainty in 2018
• Show visibility progress from 1996 to 2018
• Evaluate the significance of mobile sources and
  road dust on visibility
• Topic of todays presentation

3
Mobile Source Significance Test Metric(Draft
Memo from Mobile Source Forum, 06/10/02)

• Change in extinction due to Mobile Sources over a
  clean natural background for Worst 20 Observed
  Visibility Days
• Applied for 16 Class I Areas on Colorado Plateau
• No On-Road and Non-Road Mobile Source Emissions
  (Zero-Out)
• 9 Grand Canyon (GC) States
• California
• Phoenix MSA
• Las Vegas MSA

4
Estimate 2018 Visibility using Model Scaling of
1996 Observations

• Scale observed 1996 concentrations using Relative
  Reduction Factors (RRFs)
• Separate for each Class I Area
• Separate for each species (SO4, NO3, OC, EC,
  Soil, and CM)
• Calculate based on the mean of the Worst 20
  observed visibility days during 1996
• e.g., SO42018 SO4Obs_1996 x (SO4Model
  _2018/SO4Model_1996)

5
Mobile Source Significance Test -- Accounting
for Missing Fugitive Dust Emissions

• No Wind Blown Dust in emissions inventory
• Model results for Fine Soil and Coarse Matter
  (CM) are missing major sources
• Cannot use relative changes in modeling results
  for Soil and CM
• Set RRF(Soil) RRF(CM) 1.0
• i.e., 2018 CMSoil 1996 CMSoil
• Not an issue for Mobile Source Significance Test
  as Mobile Source Soil and CM insignificant

6
Summary of Anthropogenic Emissionsin 9 Grand
Canyon (GC) States(No Biogenic, Geogenic, Fire,
or Wind Blown Dust Emissions)
7
Comments on Emissions in 9 GC States

• 47 NOX due to Mobile Sources
• (64 Non-Road vs. 36 On-Road)
• 21 SO2 due to Mobile Sources
• Almost all (97) due to Non-Road Sources
• Non-Road gas engines use low sulfur gasoline
• Non-Road Rules for some Non-Road equipment
  expected before 2018 that would significantly
  reduce diesel sulfur content (4000 ppm to 15
  ppm)
• Mobile PM10 is 6 of total but consists of EC
  OC with high light extinction efficiencies
• New soon to be released EPA NONROAD model results
  in substantial reductions in emissions

8
Preliminary Mobile Source Significance
Calculation Caveats

• Still problems with SMOKE emissions processing,
  emission inputs for scattered days sometimes get
  corrupted
• Screened out known bad days and get qualitatively
  same result
• Results consistent with previous No On-Road
  Mobile and Bounding Mobile runs
• Still problems with No Las Vegas Mobile runs so
  not presented here
• Results are preliminary and the final numbers may
  change slightly, but basic results will remain
  unchanged

9
Mobile Source Draft Significance Thresholds
(Draft Memo from Mobile Source Forum, 06/10/02)

• Draft Cumulative Approach due to Mobile Sources
  in 9 GC States
• If lt 10, then individual area significant
  thresholds of gt 5 shall be used
• If gt 10, then individual area significant
  thresholds of gt 1 shall be used
• Excludes area if it is in lowest 20 of
  contributions to the cumulative impact
• Draft Individual Area Approach Significance
• Approach1 gt 10
• Approach2 gt 1

10
Cumulative Mobile Source Significance Test
11
Preliminary Individual Area Mobile Significance
Test
12
Details Mobile Source Significance Test9 GC
States and Phoenix
13
Comments on Mobile Significance Calculations

• Effects of High Sulfur Diesel in Non-Road
• If Non-Road SO2 emissions are reduced by 75, MS
  significance reduced but still gt 10/1
• Effects of New NONROAD Model
• Substantially lower, no numbers available
• If Applied Sig Test to On-Road Mobile Only
• Approximately a factor of 3 reduction
• Expect Cumulative lt 10 Individual lt 5
• Use 2018 Background Visibility instead of 2064
• Reduce impacts by 1/3 to 1/2

14
Road Dust Significance Results

• Road Dust mainly in Soil and CM components so
  cannot use scaled modeling results
• Currently Road Dust is 20 of PM10 emissions in 9
  GC States (w/o wind blown dust)
• Use Absolute Modeling Results
• Results presented at Denver 06/10/02 WRAP
  Workshop No Road Dust in the Entire Domain
• Will be conservative (overestimate) of Road Dust
  emission impacts for 9 GC States
• Cumulative impact from 0.80 to 3.13

15
Road Dust Emissions Significance TestUsing W20
Absolute Model Results (No RRFs)