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NO 2 Increment Consumption Study in Southwest Wyoming

NO 2 Increment Consumption Study in Southwest Wyoming. Ken Rairigh State of Wyoming DEQ - Air Quality Division WESTAR Oil and Gas Workshop Pinedale, Wyoming September 13, 2007. Background.

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NO 2 Increment Consumption Study in Southwest Wyoming

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  1. NO2 Increment Consumption Study in Southwest Wyoming Ken Rairigh State of Wyoming DEQ - Air Quality Division WESTAR Oil and Gas Workshop Pinedale, Wyoming September 13, 2007

  2. Background • Concerns about cumulative impact of new oil & gas development on air quality in SW WY, especially in Bridger and Fitzpatrick Wilderness (Class I areas) • Significant growth in O&G production in Sublette Co. in last couple of years, and lots more on the way! • Cumulative increment consumption demonstration needed NOW (Dec. 2004) to inform decision making on pending permits and future development plans

  3. Goals & Outcomes • Evaluate NO2 increment in Class I areas • Evaluate impacts due to ongoing oil and gas development in Sublette County • Evaluate significance of non-road, on-road, and oil and gas NOx sources w.r.t. increment cons. • what level of refinement is needed for the emission inventories ? • Develop a manageable analysis

  4. Goals & Outcomes Cont’d. • Evaluate ISCST3, ISCLT3 and CALPUFF model predictions in near-field and “mid-field” applications • Source-Class I receptor distances = 18 -70 km • Look at NOx sources out to 300 kilometers • current “limit” of CALPUFF based on EPA guidance • Develop a model-ready database for ISC3 models and CALPUFF modeling system • Produce scientifically-credible results

  5. Regulatory Guidance Used to Develop Analysis • Developed all phases of NO2 increment analysis (Task 1 – Task 4) using EPA guidance: • Revised Guideline on Air Quality Models (April 2003) * • EPA NOx increment analysis memo (~ 1993) • IWAQM Phase 2 (December 1998) • Revised Guideline on Air Quality Models (Nov. 2005) Used current (2005) version of EPA models *

  6. Wells and Point Sources

  7. What is Increment ? • Developed to keep air quality in clean areas from deteriorating to ambient standards • For NO2: Minor Source Baseline Date = Feb 26, 1988 • Changes in actual emissions from all sources after this date affect the available increment • Increment consumption determined through dispersion modeling analyses • Pairing of model predicted concentrations in space and time (current – baseline)

  8. Calculation of NO2 Increment • Snapshot approach: • Model Current year (CY) annual average NO2 concentrations from all sources in EI • Model Baseline year (BL) annual average NO2 concentrations from all sources in EI • Subtract (CY – BL) conc. at each model receptor

  9. NO2 Increments • NO2 PSD Increments • Class II: 25 ug/m3 annual average • Class I: 2.5 ug/m3 annual average • NO2 Ambient Air Quality Standard • NAAQS/WAAQS: 100 ug/m3 annual average

  10. Inside-Out Methodology • Tasks 1-4 developed as modular components • Emissions Inventory was broken into “pieces” • NO2 increment calculated for each “piece” - additive, moving outwards from the receptor grids/Sublette County • Allowed us to: • Evaluate significance of modeled NO2 concentrations from each source category in key areas • Vary the resolution of area sources, receptor grids, and meteorology using key source categories in sensitivity analyses • Minimize model run times => get answers to the boss !

  11. D3 D3 D1 D2

  12. D3 D1 D3 D2

  13. NOx Emissions InventorySublette County • Stationary Sources • Point Sources - Sublette County NOx sources • 2002/2004 emissions inventories • Separate source groups “actual 2004” and permitted, NYC • Area Sources • Petroleum Field Sources • 2002/2004 Sublette County emissions by well • Drill rig emissions in Pinedale field were limited to May – Nov 15 Other Pinedale source emissions - year-round • Drill rig emissions in all other fields - year-round

  14. NOx Emission Inventory Sublette County • Oil & Gas Production (well sites) • Actual 2002 (Task 1) and 2004 (Tasks 2-4) and 1987 inventories • Process Heaters • Drill Rig Emissions • Well Completions/recompletions/testing • Mobile (on-road & off-road), Agriculture, Rec Marine, Cities • Actual 2002 and 1987 (baseline) inventories • Point Sources Sublette County (compressor stations) • Actual 2004 and 1987 (baseline) inventories • Allowable emissions for sources permitted, but not yet constructed

  15. NOx Emissions Summary Sublette County (TPY)

  16. Model Selection ??

  17. EPA GAQM References on Model Selection • “EPA completed limited evaluation of several long range transport (LRT) models … Based on the results, EPA concluded that long range and mesoscale transport models were limited for regulatory use to a case-by-case basis.” • “It was concluded from these case studies that the CALPUFF dispersion model had performed in a reasonable manner, and had no apparent bias toward over or under prediction, so long as the transport distance was limited to less than 300 km.”

  18. EPA GAQM References on Model Selection • “CALPUFF is intended for use on scales from tens of meters from a source to hundreds of kilometers.” • “CALPUFF is appropriate for long range transport (source-receptor distances of 50km to 200km) of emissions from point, volume, area, and line sources.”

  19. EPA GAQM References on Model Selection • … “there are certain applications containing a mixture of both long range and short range source-receptor relationships in a large modeled domain.” • “To properly analyze applications of this type, a modeling approach is needed which has the capability of combining, in a consistent manner, impacts involving both short and long range transport.”

  20. Model Selection • ISCST3, ISCLT3, and CALPUFF models • ISC3 and CALPUFF models have EPA Guideline Model status • ISCST3 currently has “alternative” model status under GAQM • ISCST3 and ISCLT3 models use nearly identical algorithms to handle pollutant transport and dispersion • CALPUFF applies puff-based advection scheme, chemistry & deposition

  21. Task 1 Modeling • Initial model runs were needed to jump start IC analysis: • 2002 EI (including Bridger and Naughton power plants in SW WY) • Existing met data for ISC3 models (Jonah site: 1999-2003) • Existing 1995 wind field (SWWYTAF study) • 4 km receptor grids in Class II areas • 2 km spacing along boundary of the Bridger-Fitzpatrick Class I areas (as used in previous PSD increment modeling studies) • NPS receptors in the interior of the Bridger-Fitzpatrick Class I area • Compare CALPUFF/ISC3 model predictions (annual ave.) • Evaluate Model run times

  22. MM5 and CALMET Domains MM5 20 km MM5 60 km SWWYTAF CALMET

  23. Class I Receptor Grids ~ 1 km spacing (http://www2.nature.nps.gov/air/Maps/Receptors) 2 km interior spacing

  24. Class II Receptor Grids

  25. Task 1 Modeling • Ran ISCST3, ISCLT3, and CALPUFF models • Modeled identical emission sources and emission rates in all model simulations and sensitivity analyses • Compared effects of using 5 years of hourly meteorological data 1999-2004 (ISCST3) against an “annualized” version of this meteorological data (ISCLT3), and 1995 CALMET 4 km • Obtained results within 7 weeks of contract initiation • Similar results from all three (3) models in most all cases • Max annual NO2 (CALPUFF no-chemistry) • Class I IC ~ 0.5 ug/m3 • Class II IC ~ 6.4 ug/m3

  26. Task 2 Modeling • Updated O&G EI – 2004 • Ran additional sensitivity analyses using higher resolution terrain data • Varied area source and meteorological grid sizes • Added more receptors • Used CALPUFF to evaluate sources located within 200 km of Bridger and Fitzpatrick Class I areas • ISC/CALPUFF comparisons limited to Sublette Co

  27. D1 Oil & Gas Area Sources - 2004

  28. D1 Oil & Gas Area Sources - 1987

  29. Oil & Gas Area Sources

  30. Sensitivity Analyses • Chemistry Modules • Area source resolution • Grid cell (meteorological) resolution • Receptor grid resolution • Puff splitting • Terrain elevation (DEM) data

  31. Chemistry Modules • Conducted CALPUFF model runs using: 1) Inert (“no chemistry”) and no deposition 2) Inert with dry NOx deposition turned on 3) MESOPUFF II chemical module (NOx concentrations only) 4) RIVAD/ARM3 chemical module => NO, NO2 and NOx concentrations

  32. Chemistry Modules • Using RIVAD chemical module => average NO to NO2 conversion factors vary from 60% to over 90% depending on source – receptor distance • Results from Task 2 show that the RIVAD NO to NO2 rate is higher than the rate obtained using MESOPUFF II • Guidance on use of chemistry module is not specific to increment modeling

  33. Area Source Resolution • Sensitivity analyses - CALPUFF and ISC3 • combined effect of using: • 1 km area sources • 1 km receptor grid • Nearly always produced the highest near-field concentrations • No significant difference in modeled conc. at Class I areas

  34. Grid Cell Resolution • Near-field maximum area source NO2 impacts not sensitive to the choice of 4 km or 1 km for the grid cell resolution • Within the Class I areas, NO2 concentration differences using 1 km and 4 km were small • Use of 1 km grid cells to model geographic areas outside of Sublette County => long CALPUFF run times

  35. Class II Impacts: (ISC Vs. CALPUFF) ISC NO2 = 0.75 * NOx CALPUFF NO2 (RIVAD chemistry) Maximum values unpaired in space

  36. CALPUFF Vs. ISCConclusions • High spatial correlation in annual average results • CALPUFF predicts ~ 30% higher near-source maximum NOx concentrations (puff recirculation ??) • Increment consumption largely independent of year-to-year meteorological variations • Need monitoring data for model performance evaluations

  37. Task 2 Modeling Results • Maximum annual NO2 – CALPUFF • 4 km meteorological data resolution • 1 km area source resolution • RIVAD chemical mechanism • No puff splitting • Class I NO2 Increment Cons ~ 0.14 ug/m3 • Class II NO2 Increment Cons ~ 11.5 ug/m3

  38. Selected Model Configuration Task 3 and 4 • RIVAD chemistry module • 1 km resolution for area sources inside Sublette County, 4 km everywhere outside • 4 km grid cell (meteorological) resolution • 4 km receptor grid over all of Sublette Co. and 1 km receptor grid over highest areas of NOx emissions • Use NPS receptor grid in Class I areas • Puff splitting option turned off • 7.5 minute DEM data for terrain in WY

  39. NOx Inventory by Domain

  40. BASELINE OIL & GAS AND POINT SOURCES

  41. CURRENT OIL & GAS AND POINT SOURCES

  42. Baseline NO2 Concentration All Wyoming (D1xx and D2) and non-WY Sources ** 1995 LCP Meteorology ** Maximum Modeled NO2 Conc = 8.87 ug/m3 Class II area max NO2 100 8 80 6 5 60 4 ) m k 3 40 ( y P C 2.5 L 2 20 1.5 1 0 0.5 0 -20 ug/m3 -160 -140 -120 -100 -80 -60 -40 -20 LCPx (km)

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