Cdc Aqtsd Feis 04-2016
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4. FAR-FIELD MODELING 2008 2022 2022 - 2008 Figure 4-5. CAMx model results for 1-hour NO2. Left and center panels: 2008 and 2022 absolute model results for 1-hour NO2 from all regional emissions sources, including CD-C Project. Right panel: 2022-2008 difference in 1-hour NO2. All three panels show average of results for the 2005 and 2006 meteorological years. Figure 4-6 shows the contribution of the CD-C Proposed Action Alternative (8950 new wells) and the CD-C No Action Alternative (4063 new wells) emissions to regional NOX. For comparison, the NO2 field for 2022 is shown in the left hand panel; this panel is identical to the middle panel of Figure 4-5. The maximum CD-C NOX contributions (which are conservative estimates of the CD-C contributions to regional NO2) from the Proposed Action Alternative and No Action Alternative emissions are 44 and 20 µg m-3, respectively. Although the CD-C Proposed Action makes a discernible contribution to regional 1-hour NO2, the impacts are localized and there is no exceedance of the 1-hour NO2 NAAQS, WAAQS, and CAAQS. 1-Hour Average NO2 CD-C Proposed Action CD-C No Action All sources NOx Contribution NOx Contribution Figure 4-6. Left panel: 2022 absolute model results for 1-hour NO2 from all regional emissions sources, including CD-C Project. Center panel: CD-C Proposed Action Alternative contribution to 2022 1-hour NOX. Right panel: CD-C No Action Alternative contribution to the 2022 1-hour NOX. All three panels show 1-hour average of results for the 2005 and 2006 meteorological years. Continental Divide-Creston Natural Gas Development Project Final EIS • April 2016 4-24 4. FAR-FIELD MODELING Results for regional annual average NO2 are shown in Figure 4-7. The spatial pattern of the annual NO2 results is similar to that of the 1-hour NO2 results, although the maxima are lower due to the longer averaging time. The NAAQS, WAAQS, and CAAQS for annual average NO2, are identical and are 100 µg m-3. The maximum value within the 4 km domain in 2022 is 32 µg m-3: the NAAQS is therefore attained throughout the 4 km domain. In 2022, modeled annual -3 average NO2 is generally below 15 µg m except near large point sources and regions of oil and gas and trona development. As with 1-hour NO2, the CD-C Project emissions contribute NOX to regional levels (Figure 4-8). The peak values of the Proposed Action Alternative and No Action Alternative NOX contributions are 6.3 and 2.9 µg m-3, respectively. The Proposed Action Alternative contribution is approximately half of the regional value of annual average NO2 in the vicinity of -3 the CD-C Project. However, the annual average NO2 values of 10-15 µg m near the CD-C Project Area are well below the NAAQS of 100 µg m-3. 2008 2022 2022 - 2008 Figure 4-7. CAMx model results for annual average NO2. Left and center panels: 2008 and 2022 absolute model results for annual average NO2 from all regional emissions sources, including CD-C Project. Right panel: 2022-2008 difference in annual average NO2; all three panels show average of results for the 2005 and 2006 meteorological years. Continental Divide-Creston Natural Gas Development Project Final EIS • April 2016 4-25 4. FAR-FIELD MODELING -Hour Average NO2 CD-C Proposed Action CD-C No Action All sources NOx Contribution NOx Contribution Figure 4-8. 2022 absolute model results for annual average NO2 from all regional emissions sources, including the CD-C Project. Center panel: CD-C Proposed Action Alternative contribution to 2022 annual average NOX. Right panel: CD-C No Action Alternative contribution to the 2022 annual average NOX. All three panels show 1-hour average of results for the 2005 and 2006 meteorological years. Figure 4-9 shows the results for 1-hour average SO2. The NAAQS, WAAQS, and CAAQS for 1- -3 -3 hour average SO2 is 196 µg m . 1-hour average SO2 values are generally below 100 µg m except near large point sources. There are two localized regions with 1-hour SO2 exceeding 196 µg m-3 within the 4 km domain in 2022; the maximum value is 230 µg m-3 in central Fremont County, the other exceedance is 222 µg m-3 in western Sweetwater County, both exceedances are on a single grid cell only. The NAAQS, WAAQS and CAAQS are attained everywhere else within the domain. High 1-hour SO2 in Fremont County occurs in the vicinity of a high-emitting (~1400 tpy) point source associated with Peak Sulfur, Inc. and with a single grid cell containing high (~1500 tpy) area source SO2 emissions due to industrial fuel combustion. High SO2 is present in this Fremont County location in both the 2008 baseline and 2022 future year emission inventories. These predicted exceedances are not related to the CD-C project and in the absence of the CD-C project emissions modeled concentrations at these locations would be comparable. The right hand panel of Figure 4-9 shows changes in 1-hour SO2 between the 2008 base year and the 2022 future year. There are SO2 emissions reductions at the Jim Bridger and Naughton EGUs in Wyoming, and there are large SO2 increases in 2022 at point sources in Carbon and Uinta counties. The CD-C Proposed Action and No Action contributions to 1-hour SO2 are shown in Figure 4-10. The SO2 contribution from CD-C sources is extremely small, and is not visible on the same scale used to view regional SO2. The small CD-C contribution to SO2 is consistent with the fact that the Project’s SO2 emissions are small, since the Project does not access reservoirs containing sour gas. Based on the size of the CD-C contribution to regional 1-hour SO2, we conclude that neither the Proposed Action Alternative nor the No Action Alternative emissions contribute to modeled exceedances of 1-hour SO2 ambient air quality standards in Fremont or Sweetwater counties. Continental Divide-Creston Natural Gas Development Project Final EIS • April 2016 4-26 4. FAR-FIELD MODELING 2008 2022 2022 - 2008 Figure 4-9. CAMx model results for 1-hour SO2. Left and center panels: 2008 and 2022 absolute model results for 1-hour SO2 from all regional emissions sources, including CD-C Project. Right panel: 2022-2008 difference in 1-hour SO2. All three panels show average of results for the 2005 and 2006 meteorological years. 1-Hour Average SO2 CD-C Proposed Action CD-C No Action All sources SO2 Contribution SO2 Contribution Figure 4-10. Left panel: 2022 absolute model results for 1-hour SO2 from all regional emissions sources, including CD-C Project. Center panel: CD-C Proposed Action Alternative contribution to the 2022 1-hour SO2 shown in the left hand panel. Right panel: CD-C No Action Alternative contribution to the 2022 1-hour SO2 shown in the left hand panel. All three panels show average of results for the 2005 and 2006 meteorological years. Continental Divide-Creston Natural Gas Development Project Final EIS • April 2016 4-27 4. FAR-FIELD MODELING CAMx results for 3-hour SO2 are shown in Figure 4-11. The NAAQS and WAAQS for 3-hour SO2 -3 -3 are 1,300 µg m , while the CAAQS is 700 µg m . 3-hour SO2 values within the 4 km domain are generally below 200 µg m-3 except in the vicinity of large point sources. The maximum value -3 within the 4 km domain in 2022 is 216 µg m ; all 3-hour SO2 standards are attained throughout the 4 km domain. The largest SO2 increase going from 2008 to 2022 occurs in Uinta County, as noted in the discussion of 1-hour SO2. As for 1-hour SO2, contributions to 3-hour SO2 from the Proposed Action Alternative emissions and the No Action Alternative emissions are too small to be seen on the same scale as regional SO2 (Figure 4-12). 2008 2022 2022 - 2008 Figure 4-11. CAMx model results for 3-hour SO2. Left and center panels: 2008 and 2022 absolute model results for 3-hour SO2 from all regional emissions sources, including CD-C Project. Right panel: 2022-2008 difference in 3-hour SO2. All three panels show average of results for the 2005 and 2006 meteorological years. 3-Hour Average SO2 CD-C Proposed Action CD-C No Action All sources SO2 Contribution SO2 Contribution Figure 4-12. Left panel: 2022 absolute model results for 3-hour SO2 from all regional emissions sources, including CD-C Project. Center panel: CD-C Proposed Action Alternative contribution to the 2022 3-hour SO2 shown in the left hand panel. Right panel: CD-C No Action Alternative contribution to the 2022 3-hour SO2 shown in the left hand panel. All three panels show average of results for the 2005 and 2006 meteorological years. Continental Divide-Creston Natural Gas Development Project Final EIS • April 2016 4-28 4. FAR-FIELD MODELING CAMx results for 24-hour SO2 are shown in Figure 4-13. Although the NAAQS and WAAQS have -3 been revoked the 24-hour SO2 CAAQS of 365 µg m is still applicable. 24-hour SO2 values within the 4 km domain are generally below 40 µg m-3 except in the vicinity of large point sources. The -3 maximum value within the 4 km domain in 2022 is 126 µg m ; all 24-hour SO2 standards are attained throughout the 4 km domain.