1



## EPA Technical Support Document in Review of Colorad o Department of Public Health and Environment’s Demonstration Packa ge for the March 11, March 15, March 18, March 29, March 30, March 31, April 23, April 29, and November 10, 2014 Lamar Exceptional E vents

EXCEPTIONAL EVENTS RULE REQUIREMENTS

The Environmental Protection Agency (EPA) promulgat ed the Exceptional Events Rule (EER) in 2007, pursuant to the 2005 amendment of Clean Air Act (CA A) Section 319. 42 U.S.C. §7619. The EER added 40 CFR 50.1(j), (k) and (l); 50.14; and 51.930 to t he Code of Federal Regulations (CFR). These section s contain definitions, criteria for EPA approval, pro cedural requirements, and requirements for air agen cy demonstrations, all of which must be met before EPA can concur under the EER on the exclusion of air quality data from regulatory decisions.

Under 40 CFR 50.14(c)(3)(iv), the air agency demons tration to justify exclusion of data must provide evidence that:

• The event satisfies the criteria set forth in 40 CF R 50.1(j) for the definition of an exceptional event;

• The event affects air quality;

• The event is not reasonably controllable or prevent able; and

• The event is caused by human activity that is unlik ely to recur at a particular location or [is] a natural event. 1

• There is a clear causal relationship between the me asurement under consideration and the event that is claimed to have affected the air quality in the area;

• The event is associated with a measured concentrati on in excess of normal historical fluctuations, including background; and

• There would have been no exceedance or violation bu t for the event.

This review applies the EPA’s “Interim Guidance of the Preparation of Demonstrations in Support of Requests to Exclude Ambient Air Quality Data Affect ed by High Winds Under the Exceptional Events Rule” of May 2013, (Interim Guidance for High Wind Exceptional Events) in addition to the applicable statutory and regulatory provisions.

1 A natural event is further described in 40 CFR 50. 1(k) as “an event in which human activity plays lit tle or no direct causal role”.2



## Table of Contents
Summary

.................................................. ................................................... .................................................. 4
March 11, 2014 ....................................

................................................... .................................................. 6 March 15, 2014............................................................................................................... .......................................7 March 18, 2014............................................................................................................... .......................................9 March 29, 2014............................................................................................................... .....................................11 March 30, 2014............................................................................................................... .....................................13 March 31, 2014............................................................................................................... .....................................16 April 23, 2014............................................................................................................... ........................................18 April 29, 2014............................................................................................................... ........................................20 November 10, 2014...................................................................................................... .......................................22

Not Reasonably Controllable or Preventable

.................................................. .......................................... 25
March 11, 2014 ....................................

................................................... ................................................ 27 March 15, 2014............................................................................................................... .....................................28 March 18, 2014............................................................................................................... .....................................29 March 29, 2014............................................................................................................... .....................................30 March 30, 2014............................................................................................................... .....................................31 March 31, 2014............................................................................................................... .....................................32 April 23, 2014............................................................................................................... ........................................33 April 29, 2014............................................................................................................... ........................................34 November 10, 2014...................................................................................................... .......................................35

Historical Fluctuations

.................................................. ................................................... ........................... 51
March 11, 2014 ....................................

................................................... ................................................ 51 March 15, 2014............................................................................................................... .....................................51 March 18, 2014............................................................................................................... .....................................51 March 29, 2014............................................................................................................... .....................................51 March 30, 2014............................................................................................................... .....................................51 March 31, 2014............................................................................................................... .....................................52 April 23, 2014............................................................................................................... ........................................52 April 29, 2014............................................................................................................... ........................................52 November 10, 2014...................................................................................................... .......................................52

Clear Causal Relationship

.................................................. ................................................... ...................... 53
March 11, 2014 ....................................

................................................... ................................................ 54 March 15, 2014............................................................................................................... .....................................54 March 18, 2014............................................................................................................... .....................................55 March 29, 2014............................................................................................................... .....................................55 March 30, 2014............................................................................................................... .....................................56 March 31, 2014............................................................................................................... .....................................59 April 23, 2014............................................................................................................... ........................................623

April 29, 2014............................................................................................................... ........................................64 November 10, 2014...................................................................................................... .......................................65

Affects Air Quality

.................................................. ................................................... ................................. 66

Natural Event

.................................................. ................................................... ......................................... 67

No Exceedance But For the Event

.................................................. ................................................... ......... 69
Schedule and Procedural Requirements

.................................................. ................................................. 7 0

Conclusion

.................................................. ................................................... ............................................. 714



## SUMMARY

Overview

On May 7, 2015 the Colorado Department of Public He alth and Environment (CDPHE) submitted a demonstration (termed a Technical Support Document or TSD) for exceptional event exceedances of the 24-hour PM 10 standard that occurred at the monitoring station in Lamar on March 11, March 15, March 18, March 29, March 30, March 31, April 23, April 2 9, and November 10, 2014. Table 1 summarizes the exceedance that CDPHE would like considered for exc eptional event concurrence in the Air Quality System (AQS) database.

Table 1: EPA PM 10 Exceedance Summary of the 150 ug/m 3 24-hour NAAQS Exceedance Date Monitor/Site Name AQS ID 24-hour Av g. (ug/m 3 ) CDPHE Request

to Consider for AQS Removal? March 11, 2014 Lamar Municipal Building 08-99-0002 387 Yes

March 15, 2014 Lamar Municipal Building 08-99-0002 173 Yes

March 18, 2014 Lamar Municipal Building 08-99-0002 299 Yes

March 29, 2014 Lamar Municipal Building 08-99-0002 263 Yes

March 30, 2014 Lamar Municipal Building 08-99-0002 264 Yes

March 31, 2014 Lamar Municipal Building 08-99-0002 223 Yes

April 23, 2014 Lamar Municipal Building 08-99-0002 350 Yes

April 29, 2014 Lamar Municipal Building 08-99-0002 321 Yes

November 10, 2014 Lamar Municipal Building 08-99-0002 298 Yes

Lamar sits at 3,645 feet and is in southeastern Col orado on the Arkansas River. South and southwest of Lamar are the high, semi-arid plains of New Mexico, north Texas, and the Oklahoma panhandle. Further west and southwest of Lamar are the deserts of the New Mexico, Utah, and Arizona Four Corners region. The areas described are shown in Figures 1 and 2.5

Figure 1: Map of Desert, Four Corners, and Monitor Location with the PM 10 NAAQS Exceedances

Figure 2: Map of High Plains and Monitor Location w ith the PM 10 NAAQS Exceedances6

March 11, 2014:

The exceedance in Lamar was the result of intense s urface winds in the wake of a passing cold front. These surface features were associated with a strong upper-level trough that was moving across the western United States. The surface winds were predominantly out of a north to northeasterly direction which moved over dry soils in eastern Colorado, producing significant blowing dust. 2

EPA Figure 3 from CDPHE’s demonstration visually de monstrate the passing cold front over southeastern Colorado at 5:00 AM and Figure 4 shows it moving over northern Texas at 11:00 AM. Figure 1 through Figure 11 from CDPHE’s demonstrati on (not all included here) use modeling, meteorology, and monitoring analysis to support the evidence of wind direction and reach of the dust storm into Lamar.

Figure 3: Cold Front Surface Analysis at 5 AM on Ma rch 11, 2014 (CDPHE’s TSD Figure 4) 3

2 “TSD for the 2014 Lamar Exceptional Events,” May 7 , 2015, page 14.

3 Ibid., 18.7

Figure 4: Cold Front Surface Analysis at 11 AM on M arch 11, 2014 (CDPHE’s TSD Figure 5) 4

March 15, 2014:

The exceedance in Lamar was the result of intense s urface winds which were produced by a very strong upper-level trough that was moving across th e western United States. The surface winds were predominantly out of a northerly direction whi ch moved over dry soils in eastern Colorado, producing significant blowing dust. 5

EPA Figures 5 and 6 from CDPHE’s demonstration show an:

“upper-level trough associated with this storm syst em is shown on the 700 mb and 500 mb height analysis maps at 5:00 AM MST, March 15, 2014... These two charts show that a deep trough of low pressure was present at both the 700 and 500 mb level just a few hours before the onset of the blowing dust event of March 15 and that it was movi ng over the southwestern United States. This is a typical upper-air pattern for blowing dust eve nts in Colorado” 6

Figure 12 through Figure 19 in CDPHE’s demonstratio n (not all included here) use modeling, meteorology, and monitoring analysis to support the evidence of wind direction and reach of the dust storm into Lamar.

4 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 18.

5 Ibid., 28.

6 Ibid., 288

Figure 5: 700 mb Upper Level Trough Storm System An alysis at on March 15, 2014 (CDPHE’s TSD Figure 13) 7

7 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 29.9

Figure 6: 500 mb Upper Level Trough Storm System An alysis at on March 15, 2014 (CDPHE’s TSD Figure 14) 8

March 18, 2014:

The exceedance in Lamar was the result of intense s urface winds which were produced by a very strong upper-level trough that was moving across th e western United States. The surface winds were predominantly out of a north to northwesterly direction which moved over dry soils in eastern Colorado, producing significant blowing dus t. 9

EPA Figures 7 and 8 from CDPHE’s demonstration show an:

“upper-level trough associated with this storm syst em is shown on the 700 mb and 500 mb height analysis maps at 5:00 AM MST, March 18, 2014 ... Thes e two charts show that a deep trough of

8 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 30.

9 Ibid., 37.10

low pressure was present at both the 700 and 500 mb level at the onset of the blowing dust event of March 18, 2014, and that it was moving over the southwestern United States. This is a typical upper-air pattern for blowing dust events in Colora do” 10

Figure 20 through Figure 28 in CDPHE’s demonstratio n (not all included here) use modeling, meteorology, and monitoring analysis to support the evidence of wind direction and reach of the dust storm into Lamar.

Figure 7: 700 mb Upper Level Trough Storm System An alysis at on March 18, 2014 (CDPHE’s TSD Figure 21) 11

10 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 38.

11 Ibid., 39.11

Figure 8: 500 mb Upper Level Trough Storm System An alysis at on March 18, 2014 (CDPHE’s TSD Figure 22) 12

March 29, 2014:

The exceedance in Lamar was the result of intense s urface winds which were produced by a strong upper-level trough that was moving across th e western United States. The surface winds were predominantly out of a south to southwest dire ction which moved over dry soils in southeast Colorado, producing significant blowing dust. 13

EPA Figures 9 and 10 from CDPHE’s demonstration sho w the upper-level trough associated with this storm system at 700 mb height analysis maps at 11:0 0 AM MST, March 29, 2014. Figure 9 shows “that a

12 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 40.

13 Ibid., 48.12

deep trough of low pressure was entering southeast Colorado at the onset of the blowing dust event of March 29. In advance of this upper-level trough was a band of high winds ranging from 25-35 kts (29-40 mph), including over Lamar and areas downwind (sout h to southwest).” 14 While Figure 10 shows:

“ that relatively deep atmospheric mixing was occurri ng over southeast Colorado at the same time the 700 mb jet streak was overhead. Mixing of 2.5-3 .5 km above mean sea level (MSL) over Lamar and areas upwind would have been sufficient t o transfer momentum to the surface from the zone of strong winds that were present at 700 m b (about 3 km above MSL).” 15

Figure 29 through Figure 37 in CDPHE’s demonstratio n (not all included here) use modeling, meteorology, and monitoring analysis to support the evidence of wind direction and reach of the dust storm into Lamar.

Figure 9: 700 mb Upper Level Trough Storm System Lo w Pressure Analysis on March 29, 2014 (CDPHE’s TSD Figure 30) 16

14 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 48.

15 Ibid., 48.

16 Ibid., 49.13

Figure 10: 700 mb Upper Level Trough Storm System M ixed Layer Analysis on March 29, 2014 (CDPHE’s TSD Figure 31) 17

March 30, 2014:

The exceedance was the result of an intense upper-l evel trough producing strong winds in southeast Colorado which transported blowing dust i nto the Lamar area. The surface winds were predominantly out of a west to southwest direction which moved over dry soils in southeast Colorado, producing significant blowing dust. 18

EPA Figures 11 and 12 from CDPHE’s demonstration show an upper-level trough associated with this storm system at 700 mb height analysis maps at 5:00 AM MST and 11:00 AM MST, March 30, 2014. These two figures show:

“As the trough moved over southeast Colorado (Figur e 41) during the late evening hours of March 30, the winds aloft at 700 mb intensified. Di rectly over Lamar the 700 mb wind speeds ranged from 50-60 knots (57-69 mph) at 11:00 PM MST . Mixing at this time had decreased significantly (Figure 42), but still ranged from 3- 5 km above MSL over the Lamar area.” 19

17 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 49.

18 Ibid., 57.

19 Ibid., 58.14

Figure 11: 700 mb Upper Level Trough Storm System W ind Speed Analysis at 5:00 PM on March 30, 2014 (CDPHE’s TSD Figure 39) 20

Figure 12: 700 mb Upper Level Trough Storm System W ind Speed Analysis at 11:00 PM on March 30, 2014 (CDPHE’s TSD Figure 41) 21

20 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 59.

21 Ibid., 60.15

EPA Figures 13 and 14 show:

“that a deep trough of low pressure was entering so utheast Colorado at the onset of the blowing dust event of March 30. In advance of this upper-le vel trough was a band of high winds ranging from 35-45 kts (40-52 mph), including over Lamar an d areas upwind (west to southwest)... Mixing at this time had decreased significantly (Fi gure 42), but still ranged from 3-5 km above MSL over the Lamar area. As stated in the previous paragraph, the 700 mb level is about 3 km above MSL. This indicates that atmospheric mixing a t 11:00 PM MST was still sufficient to mix down the very strong winds that were occurring at t he 700 mb level at that time.” 22

Figure 38 through Figure 51 in CDPHE’s demonstratio n (not all included here) use modeling, meteorology, and monitoring analysis to support the evidence of wind direction and reach of the dust storm into Lamar.

Figure 13: 700 mb Upper Level Trough Storm System M ixed Layer Analysis at 5:00 PM on March 30, 2014 (CDPHE’s TSD Figure 40) 23

22 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 58

23 Ibid., 59.16

Figure 14: 700 mb Upper Level Trough Storm System M ixed Layer Analysis at 11:00 PM on March 30, 2014 (CDPHE’s TSD Figure 42) 24

March 31, 2014:

The exceedance in Lamar was the result of intense s urface winds in the wake of a passing cold front. These surface features were associated with a strong upper-level trough that was moving across southeast Colorado. A secondary cold front p assage later in the day also likely contributed to the PM 10 exceedance. The surface winds in Lamar were predomi nantly out of a west to northwesterly direction which moved over dry soils in eastern Colorado, producing significant blowing dust. 25

EPA Figures 15 and 16 from CDPHE’s demonstration show an upper-level trough associated with this storm system at 700 mb height analysis maps at 11:0 0 PM MST, March 31, 2014. Figure 15 shows “that a deep trough of low pressure was moving over southea st Colorado at the onset of the blowing dust event of March 31. Directly over Lamar the 700 mb wind sp eeds ranged from 50-60 knots (57-69 mph).” 26 While the Figure 16 shows:

24 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 60.

25 Ibid., 75.

26 Ibid., 78.17

“The atmosphere at this time was still fairly unsta ble as evidenced from the height of the mixed level shown in Figure 56. Over the Lamar area, mixi ng ranged from 3-5 km above mean sea level (MSL). The 700 mb level is located roughly 3 kilome ters above MSL, so it is reasonable to believe that mixing was deep enough at 11:00 PM MST to transfer momentum to the surface from the zone of strong winds that were present at 700 mb. Winds of the magnitude found at 700 mb would have been well in excess of wind speeds th at are known to cause blowing dust in southeast Colorado (30 mph sustained winds, 40 mph gusts).” 27

Figure 52 through Figure 63 in CDPHE’s demonstratio n (not all included here) use modeling, meteorology, and monitoring analysis to support the evidence of wind direction and reach of the dust storm into Lamar.

Figure 15: 700 mb Upper Level Trough Storm System L ow Pressure Analysis on March 31, 2014 (CDPHE’s TSD Figure 55) 28

27 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 78.

28 Ibid., 78.18

Figure 16: 700 mb Upper Level Trough Storm System M ixed Layer Analysis on March 31, 2014 (CDPHE’s TSD Figure 56) 29

April 23, 2014:

The exceedance in Lamar was the result of intense s urface winds in the wake of a passing cold front. These surface features were associated with a strong upper-level trough that was moving across the western United States. Post-frontal thun derstorms with strong outflow winds may also have had a significant contribution to PM 10 concentrations. The surface winds in Lamar were predominantly out of a north to northeasterly direc tion which moved over dry soils in eastern Colorado, producing significant blowing dust. 30

EPA Figures 17 and 18 from CDPHE’s demonstration sh ow that:

The upper-level trough associated with this storm s ystem is shown on the 700 mb and 500 mb height analysis maps at 5:00 PM MST, April 23, 2014 in Figure 65 and Figure 66, respectively. The 700 mb level is located roughly 3 kilometers ab ove mean sea level (MSL) while the 500 mb level is approximately 6 kilometers above MSL. Thes e two charts show that a deep trough of low pressure was present at both the 700 and 500 mb lev el at the onset of the blowing dust event of

29 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 79.

30 Ibid., 89.19

April 23 and that it was moving over the southweste rn United States. This is a typical upper-air pattern for blowing dust events in Colorado. 31

Figure 64 through Figure 75 in CDPHE’s demonstratio n (not all included here) use modeling, meteorology, and monitoring analysis to support the evidence of wind direction and reach of the dust storm into Lamar.

Figure 17: 700 mb Upper Level Trough Storm System A nalysis at on April 23, 2014 (CDPHE’s TSD Figure 65) 32

31 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 90.

32 Ibid., 91.20

Figure 18: 500 mb Upper Level Trough Storm System A nalysis at on April 23, 2014 (CDPHE’s TSD Figure 66) 33

April 29, 2014:

The exceedance in Lamar was the result of intense s urface winds which were produced by a very strong upper-level trough that was moving across th e central United States. The surface winds were predominantly out of a north to northwesterly direction which moved over dry soils in eastern Colorado, producing significant blowing dus t. 34

33 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 92.

34 Ibid., 103.21

EPA Figures 19 and 20 from CDPHE’s demonstration sh ow that:

Eastern Colorado was on the western side of this sl ow moving, upper-level low where the winds were exceptionally strong. The North American Regio nal Reanalysis (NARR) 700 mb height analysis map of eastern Colorado shown in Figure 78 reveals that wind speeds over Lamar and upwind (north) ranged from 60-90 kts (69-103 mph) a t 5:00 AM MST, April 29, 2014. By viewing Figure 79 we can see that relatively deep a tmospheric mixing was occurring over eastern Colorado at the same time the 700 mb jet streak was overhead. Mixing of 3-5 km above MSL over Lamar and areas upwind would have been suffici ent to transfer momentum to the surface from the zone of extremely strong winds that were p resent at 700 mb (about 3 km above MSL). 35

Figure 76 through Figure 86 in CDPHE’s demonstratio n (not all included here) use modeling, meteorology, and monitoring analysis to support the evidence of wind direction and reach of the dust storm into Lamar.

Figure 19: 700 mb Upper Level Trough Storm System W ind Speed Analysis at 5:00 AM on April 29, 2014 (CDPHE’s TSD Figure 78) 36

35 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 104.

36 Ibid., 105.22

Figure 20: 700 mb Upper Level Trough Storm System M ixed Layer Analysis on April 29, 2014 (CDPHE’s TSD Figure 79) 37

November 10, 2014:

The exceedance in Lamar was the result of intense s urface winds in the wake of a passing cold front. These surface features were associated with a strong upper-level trough that was moving across the western United States. The surface winds were predominantly out of a north to northeasterly direction which moved over dry soils in eastern Colorado, producing significant blowing dust. 38

EPA Figures 21 and 22 from CDPHE’s demonstration sh ow that:

The upper-level trough associated with this storm s ystem is shown on the 700 mb and 500 mb height analysis maps at 5:00 AM MST, November 10, 2 014 in Figure 88 and Figure 89, respectively. The 700 mb level is located roughly 3 kilometers above mean sea level (MSL) while the 500 mb level is approximately 6 kilometers abov e MSL. These two charts show that a deep trough of low pressure was present at both the 700 and 500 mb level just a few hours before the

37 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 105.

38 Ibid., 116.23

blowing dust event of November 10, 2014, and that i t was moving over the western United States. This is a typical upper-air pattern for blowing dus t events in Colorado. 39

Figure 87 through Figure 96 in CDPHE’s demonstratio n (not all included here) use modeling, meteorology, and monitoring analysis to support the evidence of wind direction and reach of the dust storm into Lamar.

Figure 21: 700 mb Upper Level Trough Storm System A nalysis at on November 10, 2014 (CDPHE’s TSD Figure 88) 40

39 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 117.

40 Ibid., 117.24

Figure 22: 500 mb Upper Level Trough Storm System A nalysis at on November 10, 2014 (CDPHE’s TSD Figure 89) 41

CDPHE provides a comprehensive description and disc ussion of these events in Sections 2, 3, 4, and 5 o f the demonstration.

41 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 118.25

Not Reasonably Controllable or Preventable

EPA evaluates whether an event was not Reasonably C ontrollable or Preventable (nRCP) at the time of the event by taking into account controls in place and wind speed, along with other factors. For natural sources of dust, a high wind dust event can general ly be considered to be nRCP if winds are high enoug h to cause emissions from natural undisturbed areas. For anthropogenic sources of dust, a high wind dust event can be nRCP if:

• The anthropogenic sources of dust have reasonable c ontrols in place;

• The reasonable controls have been effectively imple mented and enforced; and,

• The wind speed was high enough to overwhelm the rea sonable controls. 42

In addressing reasonable controls, CDPHE provided d etailed information on the current set of required and voluntary controls in the Lamar area, including information on implementation of State Regulations 1, 3, 6, and 9, rule effectiveness, compliance, and public notification activities that occurred on th e event days. As CDPHE states:

The APCD conducted thorough analyses and outreach w ith local governments to confirm that no unusual anthropogenic PM 10 -producing activities occurred in these areas and t hat despite reasonable control measures in place, high wind con ditions overwhelmed all reasonably available controls... This information shall confirm that no unusual ant hropogenic actions occurred in the local areas of Lamar during this time. 43

CDPHE’s demonstration provides an analysis of the s tate and local controls in place to control PM 10 emissions. Although specifically focusing on Regula tions 1, 3 and 6, these controls include CDPHE’s:

• Regulation 1- Emission Control for Particulate Matt er, Smoke, Carbon Monoxide, and Sulfur Oxides;

• Regulation 3- Stationary Source Permitting and Air Pollutant Emission Notice Requirements;

• Regulation 4- New Wood Stoves and the Use of Certai n Woodburning Appliances During High Pollution Days;

• Regulation 6- Standards of Performance for New Stat ionary Sources; and

• Regulation 9- Open Burning, Prescribed Fire, and Pe rmitting. 44

CDPHE provided the documentation summarized in EPA Table 1, and displayed EPA Tables 2-10 (CDPHE Tables 23-32) showing that sustained wind sp eeds associated with these events were above 30 mph and gusts were above 40 mph. In fact the wind s peeds for the events averaged 40 mph and the gusts averaged to 51.33 mph. CDPHE previously established in its exceptional events demonstration for the January 19, 2009 event in Lamar, Colorado that wind speeds of 30 mph and/or gusts of 40 mph or higher have been shown to cause blowing dust in Colorado. 45 EPA Region 8 concurred with this analysis and accepts this as a legitimate threshold for evaluati ng blowing dust events in Colorado. The sustained w inds

42 “Interim Guidance on the Preparation of Demonstrat ions in Support of Requests to Exclude Ambient Air Quality Data Affected by High Winds Under the Exceptional E vents Rule,” May 2013, page 10.
43 “TSD for the 2014 Lamar Exceptional Events,” May 7 , 2015, page 182.

44 Ibid., 182-184.

45 “TSD for the January 19, 2009 Lamar Exceptional Eve nt,” November 22, 2011.26

and gusts in Lamar in 2014 exceed this Colorado thr eshold. Transported dust from the upwind desert and arid plains regions appears to be a significant con tribution to the exceedance, in addition to local w inds overwhelming implemented local controls. EPA notes that the high local gust speeds in Lamar would likely be capable of overwhelming some local contro ls. Section 5 of the TSD provided by CDPHE supports this conclusion by describing in detail “B est Available Control Measures (BACM), other reasonable control measures, applicable federal, st ate, and local regulations, appropriate land use management, and an in-depth analysis of potential a reas of local soil disturbance for Lamar during the 2014 events.” 46

Table 1: Wind and Gust Highest Measured Speeds by E xceedance Date

Exceedance Date Wind Speed in MPH Wind Gust in MPH

March 11, 2014 39 48

March 15, 2014 40 53

March 18, 2014 43 52

March 29, 2014 30 39

March 30, 2014 33 48

March 31, 2014 39 47

April 23, 2014 45 59

April 29, 2014 48 63

November 10, 2014 43 53

46 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 182.27

Table 2: Wind Speed Lamar, CO on March 11, 2014 (CD PHE’s TSD Table 1) 47

47 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 20.28

Table 3: Wind Speed Lamar, CO on March 15, 2014 (CD PHE’s TSD Table 5) 48

48 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 32.29

Table 4: Wind Speed Lamar, CO on March 18, 2014 (CD PHE’s TSD Table 7) 49

49 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 42.30

Table 5: Wind Speed Lamar, CO on March 29, 2014 (CD PHE’s TSD Table 9) 50

50 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 52.31

Table 6: Wind Speed Lamar, CO on March 30, 2014 (CD PHE’s TSD Table 10) 51, 52

51 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 63.

52 Higher wind speed upwind of the Lamar meteorologica l monitor were contributing to regional aerosol haz e covering all of Utah, northern Arizona, northern Ne w Mexico, and over half of Colorado during the late afternoon prior to high winds reaching Lamar later in the eve ning, according to Naval Advanced Aerosol Predictio n System Total Optical Depth Analysis for 5:00 PM and 11:00 PM on March 30, 2014.32

Table 7: Wind Speed Lamar, CO on March 31, 2014 (CD PHE’s TSD Table 16) 53

53 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 81.33

Table 8: Wind Speed Lamar, CO on April 23, 2014 (CD PHE’s TSD Table 18) 54

54 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 98.34

Table 9: Wind Speed Lamar, CO on April 29, 2014 (CD PHE’s TSD Table 20) 55

55 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 109.35

Table 10: Wind Speed Lamar, CO on November 10, 2014 (CDPHE’s TSD Table 23) 56

56 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 121.36

Section 2 of CDPHE’s demonstration provides a compl ex meteorological analysis of the event, including:

• Statewide PM 10 monitoring maps;

• Surface and upper air wind speed analysis from the National Oceanic and Atmospheric Administration (NOAA);

• North American Regional Reanalysis (NARR) jet strea m maximum winds;

• Maps of real-time weather data from the National Ce nter for Atmospheric Research (NCAR);

• Regional wind and weather by hour, as well as wind direction, through MesoWest;

• MODIS Terra satellite images demonstrating the blow ing dust across the region;

• Naval Advanced Aerosol Prediction System (NAAPS) fo recasted dust concentrations; and

• Maps establishing the lack of regional precipitatio n and drought status from U.S. Department of Agriculture (USDA), NOAA, and the National Drought Mitigation Center.

These analyses demonstrate persuasively through the weight of evidence the existence of high wind blowing dust events originating far from the monito r in question.

Lamar has the following controls in place: 57

• A Natural Events Action Plan (NEAP) for High Wind E vents completed in 2003, and updated in 2012, which addresses public education, notificati on, and health advisory systems as well as implements Best Available Control Measures (BACM) 58 ;

• A PM 10 Maintenance plan for the Lamar Attainment/Maintena nce Area effective since Nov. 25, 2005 with provisions for Prevention of Significant Deterioration (PSD) permitting requiring Best Available Control Technology (BACT) 59 ;

• State Implementation Plan (SIP) measures requiring owners/operators responsible for construction and/or maintenance of existing or new unpaved roadway with traffic of over 200 vehicles per day to stabilize the road to prevent f ugitive dust (see Colorado Regulation 1);

• City of Lamar BACM measures include: planting a win d-break of trees with drip-irrigation to control dust from the Lamar Transfer Station, estab lishing landfill controls such as opacity limits at 20%, fugitive dust at no more than 5.77 tons per year, and immediately shutting down the landfill when winds exceed 35 mph (per the “Operati ons and Closure Plan for the East Lamar Landfill” section 3.5.1, among other listed landfil l controls. 60 Other BACM include installing 100,000 ft 2 of turf sod and irrigation at recreational open sp ace Escondido Park, and fencing off and stabilizing lots that formerly contributed to f ugitive dust;

• Other measures include: Art. XVII, Sec. 16-17-60 re quiring off street parking lots to be swept, The Prowers County Land Use plan adopted in 2004 an d amended in 2006- through it the county has authority over “construction, siting, health, f ire, environmental codes, and other social concerns with provisions to minimize airborne dust” 61 ;

57 “TSD for the 2014 Lamar Exceptional Events,” May 7 , 2015, page 184-188.
58 Ibid., 184-185 and at: http://www.colorado.gov/airquality/tech_doc_reposit ory.aspx?action=open&file=LamarNaturalEventsActionP lan 2012.pdf.
59 “TSD for the 2014 Lamar Exceptional Events,” May 7 , 2015, 185.
60 Ibid., 185-186.
61 Ibid., 187-188.37

• Non-enforceable measures include:

o The Colorado State University CO-OP Extension Offic e efforts underway to encourage no- or low-till practices, outreach and education o n soil management programs, and drought workshops to protect topsoil;

o Voluntary and State-Only measures including weekly street sweeping and a city policy requirement that new developments have paved street s;

o The Limestone-Graveyard Creeks Watershed Project wh ich reduces soil erosion from 60,000 acres along the Arkansas River, 2,000 of whi ch are near Lamar. 99% of the 60,000 acres now have a conservation plan and are e nacting improvements created by each farmer/owner with costs of conservation improv ements split with the government.

o NRCS is promoting: a rangeland management program, a tree planting program, a drip irrigation purchase program, a multi-party drought response effort through the State of Colorado Governor’s office, and a program to incent ivize erosion mitigation. 62

• The United States Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS) Conservation Reserve Program (CRP) includes conservation provisions in the Farm Bill which encourages farmers to contract with USDA to “ place erodible cropland and other environmentally-sensitive land into long-term conse rvation practices for 10-15 years” 63 in exchange for annual rental payments and cost-share assistance from the government. This mitigation strategy is a convincing argument for th e existence of reasonable controls in place in the agricultural areas surrounding Lamar. Table 11 shows amounts of cropland under contract in surrounding counties in the years preceding the eve nts. Figure 23 shows the location of these southeast Colorado counties relative to Lamar. Chey enne and Kiowa counties are generally upwind of Lamar on days with winds from the north, while Otero, Bent, Las Animas and Baca, along with the bulk of Prowers county are upwind fr om Lamar when winds are from the south or southwest.

Table 11: Acres by County near Lamar Enrolled in th e USDA NRCS CRP Program 64 

### COUNTY 2008 2009 2010 2011 2012 2013 Bent 25,649 25,700 24,056 24,412 33,886 23,566 Kiowa 216,307 217,881 187,394 192,222 177,100 181,1 69 Baca 260,040 258,469 161,147 274,281 277,508 264,07 1 Crowley 21,419 21,461 21,069 20,329 21,917 18,490 Otero 2,559 2,864 2,706 2,851 2,054 2,635 Las Animas 21,869 21,860 17,403 17,616 18,925 18,88 7 Cheyenne 142,075 140,071 94,852 113,753 122,862 99, 074 Lincoln 155,505 155,425 137,099 145,248 118,948 116 ,289 Prowers 170,909 171,813 140,827 163,354 154,882 151 ,731 Total 1,016,333 1,015,544 786,554 954,066 928,082 875,912

62 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 218-220.

63 Ibid., 219.

64 Data for the USDA NRCS CRP program were provided as supplementary information per EPA request on April 17, 2014 by Ray Mohr of CDPHE.38

Figure 23: Southeast Colorado Counties

• Vegetation, signage, and/or other dust control meas ures are in place for undeveloped parcels of land in Lamar. Figures 24-32 below show that identi fied areas of soil disturbance have reasonable controls near the Lamar monitor. 65

o Site A is owned by Heath & Son & Turpin Trucking an d HVH Transportation Inc., a large truck repair and freight service trucking company, respectively. It is a wellmaintained gravel lot;

65 “The APCD considers restricted vehicle speeds, main tained gravel, natural vegetation, restricted acces s, pavement, compaction, re-vegetation, watering, and extraction limitation to be the appropriate available and practical method that is technologically feasible a nd economically reasonable in order to minimize fug itive particulate emissions for these sites.” “TSD for th e 2014 Lamar Exceptional Events,” May 7, 2015, page s 191-218.39 o Site B is a fenced watered-as-needed gravel lot sha red by Prowers Area Transit and the defunct Cowboy Corral Storage, feed supply, and gra in storage companies. The transit company is on a concrete slab connecting to an asph alt road;

o Site C is owned by Heath & Son & Turpin Trucking an d is a well-maintained gravel lot used for truck storage;

o Site D is the Lamar Water Department and Lamar-Prow ers County Volunteer Fire Department and is a restricted access site of grate d (sic) and watered gravel on an asneeded basis;

o Site E is the power plant that hosts the monitor an d is a restricted access lot owned by Lamar Light and Power. It has been a gas fired boil er, natural gas power plant, and coalfired boiler until being shut down in November 2011 . It was permitted under CDPHE permit #05PR0027 with the following dust control me asures: high efficiency baghouses, water wash-down systems for all surfaces to prevent dust re-entrainment, all roads were paved and inspected daily and cleaned as needed whi le under the 1 ton per year APEN exemption, transfer locations were enclosed, and th e emergency coal stockpile controlled through a water-dust suppression system;

o Site F is the Burlington Northern Santa Fe railroad and is covered in gravel 50 feet on either side of the tracks, surrounded by natural ve getation with xeriscape;

o Site G is Colorado Mills LLC sunflower oil and feed processing facility operating under CDPHE permit #95PR622. Permit conditions include 30 % maximum opacity limit, PM limits, and an Operation and Maintenance Plan. The last inspection on 2/14/12 found no visible emissions, and in-house monthly inspections and the use of cyclones for emission control demonstrate PM mitigation efforts;

o Site H is partially owned by Century Link and is a fenced gravel lot with restricted access. The remainder of the site is a free chip-se aled crushed-gravel parking lot for Prowers County Jail and the Prowers County Municipa l Court that is maintained by the county;

o Site I is owned by Prowers County and leased to the Colorado State Highway Patrol for office space. The lot is covered in gravel for dust suppression, drainage, and erosion control. Lot has restricted access and a 5 mph spee d limit;

o Site J is owned by Ranco, a heavy duty construction trailer manufacturer. The property is covered in pavement, gravel, and natural vegetation , with no unnatural, disturbed areas that may have contributed to blowing dust;

o Site K is owned by Valley glass and the property ha s restricted access to a well maintained gravel lot;40

Figure 24: Lamar Site Assessment (CDPHE’s TSD Figur e 143) 66

o Site L is owned by All-Rite Paving and Redi-Mix Inc . and is a concrete batch plant permitted by CDPHE (#12PR1396). The facility is con sidered APEN exempt and emits less than 1 ton per year of PM 10 .” 67 Baghouse collection efficiency is 99%, there is a 20% opacity limit, and water sprays and magnesium chlor ide are used on storage piles and roads as needed. There is a 10 mph speed limit, tra nsfer of materials occurs in enclosed areas, and the lot is fenced;

o Site M is mined by Carder Inc. for sand and gravel and emits no more than 15 tons per year under CDPHE permit #99PR0180F. It is a wet min ing operation to prevent fugitive dust, and uses the following preventative measures: watering as needed, re-vegetation within one year of disturbance, compacting piles, 1 0 mph speed limit, and temporary roads are graveled and watered as needed;

o Site N is restricted access property that is natura lly vegetated and undisturbed;

66 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 191.41 o Site O was mined by All-Rite Paving and Redi-Mix In c. and was a concrete batch plant permitted by CDPHE. Baghouse collection efficiency was 99%, there was a 20% opacity limit, and water sprays and magnesium chloride were used on storage piles and roads as needed. There was a 10 mph speed limit, transfer of materials occurred in enclosed areas, and the lot was fenced. 68 Partnering with the Division of Wildlife, the City of Lamar took over the lot in 2013 and has been reseeding it to c reate a fishing and wildlife park free of motorized vehicles.;

o Site P is owned by the Ranchers Supply Co. Inc. and is a fenced 90% gravel lot for longterm oversize vehicle parking. It has a 10 mph poli cy, is watered as-needed, and meets Air Quality Control Commission (AQCC) Regulation 1 requirements (Section III.D.1(a));

o Site Q is owned by Ranco, a heavy duty construction trailer manufacturer. The property is covered in pavement, gravel, and natural vegetat ion, with no unnatural, disturbed areas that may have contributed to blowing dust (duplicat e of site J above);

o Site R is C.F. Mailer Composites Inc. and is a pave d parking lot and surrounding natural vegetation with a short, maintained gravel road to a loading dock used once a day;

o Site S is owned by Prowers County and leased to the Colorado State Highway Patrol for office space. The lot is covered in gravel for dust suppression, drainage, and erosion control. Lot has restricted access and a 5 mph spee d limit (duplicate of site I above);

o Site T is Lamar Feed and Grain – White Stone Farms, CDPHE permit #00PR0431. On the property is a grain receiving pit, shipping tru ck loadout station, grain storage, grain cleaning scalper, and grain handling and milling sy stems. The permit includes dust control measures: Total PM, PM 10 and PM 2.5 annual emissions limitations, visible emissions not to exceed 20%, All equipment maintain ed consistent with good air pollution control practices, and the feed mill equi pped with a mineral oil spray system to control PM emissions;

o Site U was Dragon EPS beginning in 1993, but merged in 2011 with Ranco (site Q and J above). CPDHE permit #08PR0603 issued 12/21/11 cove rs paint booths and abrasive blasting units with the following PM controls: Perm itted annual TSP, PM 10 and PM 2.5 emission limits, High Volume Low Pressure paint spr ay guns, exhaust filters on paint spray booths, baghouse filters on blasting units, v isible emissions not to exceed 20%, source must follow CPDHE operations and maintenance plan. It was last inspected on 11/9/11 and found to be in compliance;

o Site V is a restricted access property that is natu rally vegetated and appears to be undisturbed;

o Site Y is a group of rotating crop fields, with a s chedule to allow some fields to lay fallow between plantings;42

Figure 25: Lamar Site Assessment (CDPHE’s TSD Figur e 152) 69

o Site W is the Robins Redi-Mix Concrete Batch Plant which opened in spring of 2010 and consists of a dry truck mix plant using a cement an d a dry ash silo operated with pneumatic conveyers and bag houses to control 98% o f emissions. In April 2010 CDPHE issued a permit exempt letter (10PR1310.XP) with in cludes PM point and fugitive dust control measures such as: Uncontrolled PM cannot ex ceed 10 TPY and uncontrolled
PM 10 cannot exceed 5 TPY, and visible emissions cannot exceed 20%. The source waters the lot during processing and as-needed, uses CDPHE Best Available Technology (BACT) for limestone and ash handling, paving, wash -down systems, and enclosures;

69 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 199.43

Figure 26: Lamar Site Assessment (CDPHE’s TSD Figur e 158) 70

o Site AA is Parkview Elementary School with a well m aintained gravel playground with a fence restricting vehicle access, all surrounded by trees to mitigate blowing dust;

o Site BB is large parking lot for downtown businesse s. It is mostly paved, with a small section covered in weeds (as opposed to bare dirt);

o Site CC is an undeveloped lot with a traffic barric ade to prevent cars driving on it. It is vegetated with weeds and grasses;

o Site DD is a paved parking lot and therefore not a source for PM 10;

70 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 205.44

Figure 27: Lamar Site Assessment (CDPHE’s TSD Figur e 160) 71

o Site GG is County Acres RV Park. The park is well m aintained gravel with recycled blacktop added to help with dust suppression;

o Site HH is Lamar Community College’s Equine Complex . It is a well maintained and fenced property to restrict access;

o Site II is the Lamar Ball Complex. It is fenced to limit access, covered in rotomilling (ground up asphalt) and pea gravel to help with dus t control. It is owned by the City of Lamar, and the city drags the parking lots and appl ies water as needed for dust control. The rest of the property are grass fields and turf;

o Site JJ is the Prowers County Fairgrounds. It is ma intained by the county, grated annually, and watered frequently, especially during the high use season of April to September;

o Site KK is restricted access property that is natur ally vegetated and undisturbed;

71 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 207.45

Figure 28: Lamar Site Assessment (CDPHE’s TSD Figur e 164) 72

o Site LL is the Prowers County – Walker Pit North sa nd and gravel production facility. It was issued a CDPHE permit exemption letter (09PR003 8F.XP) on 7/6/10 with the following fugitive dust control measures: Comply wi th the developed dust control plan and Comply with production rate limit. The last ins pection by CDPHE was on 3/29/14 and found to be in compliance. Previously produced areas have been re-vegetated and the area is posted with a No Trespassing sign;

72 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 209.46

Figure 29: Lamar Site Assessment (CDPHE’s TSD Figur e 167) 73

o Site MM is Washington Elementary School. It has a g ravel playground and restricted access by a surrounding fence;

73 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 212.47

Figure 30: Lamar Site Assessment (CDPHE’s TSD Figur e 170) 74

o Site NN is a metal recycling, welding, and custom f abrication business named Out West Equipment Co., Inc. and Lamar Scrap Salvage. The 3 acre lot is mostly gravel, and is watered on an as-needed basis;

o Site OO is naturally vegetated, undisturbed land;

o Site PP is restricted access property that is natur ally vegetated and undisturbed;

o Site QQ is restricted access, naturally vegetated, and undisturbed; and,

74 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 214.48

Figure 31: Lamar Site Assessment (CDPHE’s TSD Figur e 172) 75

\

o Site RR is owned by Carder, Inc. and mined as a Har d Scrabble Pit for sand and gravel for road construction. It operates under CDPHE perm it # 99PR0179FR and emits 8 TPY of PM 10 . It is a wet mining operation to control fugitive dust using the following control measures: watering disturbed areas as needed, re-ve getation within one year of disturbance, compacting of piles, mining moist mate rials, 10 mph speed limit, and temporary roads covered in gravel and watered as ne eded.

75 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 215.49

Figure 32: Lamar Site Assessment (CDPHE’s TSD Figur e 176) 76

According to CDPHE’s TSD:

The APCD conducted thorough assessments to determin e if the potential soil disturbances shown in Figure 142 through Figure 176 [EPA Figures 24 th rough 32] were present during the 2014 exceedances in Lamar. During the course of these as sessments, the APCD discovered that these sites were either reasonably controlled or consider ed to be natural sources during the 2014 high wind events. Therefore, these sites were not signif icant contributors to fugitive dust in the Lamar area during the 2014 high wind events. 77

Sections 2 and 5 of CDPHE’s demonstration show that the monitor in Lamar was affected by PM 10 transport from outside the area, with the main sour ce areas located in agricultural areas in Colorado, to the southwest in northwestern New Mexico, or to the nor th, including areas in Wyoming and Nebraska. In addition to transport, the spatial extent of elevat ed PM 10 concentrations throughout southern Colorado and the wind speeds associated with the event factor in to EPA’s evaluation of whether this event is nRCP i n Lamar. Therefore, the EPA concludes that this event was nRCP pursuant to the Treatment of Data Influenced by the EER. Table 12 summarizes the EPA’ s evaluation of CDPHE’s nRCP EE demonstration.

76 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 217.

77 Ibid., 218.50

Table 12: EPA’s Analysis of CDPHE’s TSD of nRCP
Exceedance Date Location Reasonable Controls Demonstration Citation Wind Speed

Demonstration Citation Sufficient

Quality of Evidence? EPA

Criterion Met?

March 11, 2014 Lamar Municipal

Building Section 5: p. 182-

220 Section 2: p. 14-27 Yes Yes

March 15, 2014 Lamar Municipal

Building Section 5: p. 182-

220 Section 2: p. 28-37 Yes Yes

March 18, 2014 Lamar Municipal

Building Section 5: p. 182-

220 Section 2: p. 38-47 Yes Yes

March 29, 2014 Lamar Municipal

Building Section 5: p. 182-

220 Section 2: p. 48-57 Yes Yes

March 30, 2014 Lamar Municipal

Building Section 5: p. 182-

220 Section 2: p. 58-75 Yes Yes

March 31, 2014 Lamar Municipal

Building Section 5: p. 182-

220 Section 2: p. 76-89 Yes Yes

April 23, 2014 Lamar Municipal

Building Section 5: p. 182-

220 Section 2: p. 90-102 Yes Yes

April 29, 2014 Lamar Municipal

Building Section 5: p. 182-

220 Section 2: p. 103-115 Yes Yes

November 10, 2014 Lamar Municipal

Building Section 5: p. 182-

220 Section 2: p. 116-128 Yes Yes51

Historical Fluctuations

EPA evaluates whether a measured exceedance is in e xcess of Historical Fluctuation (HF) by taking into account the level of the exceedance in relation to historical data, which is typically 3 to 5 years.

To demonstrate that this requirement was met, CDPHE provided a statistical analysis of the 2014 24-hou r average data, 6-year time series of 24-hour average s for the years of 2008-2014, and monthly data showing that all readings greater than 100 μ g/m 3 might be considered statistical outliers. The 2014 data set had 1,997 samples, and each description below i ndicates the samples taken on these days clearly exceed the typical samples for this site. CDPHE exp lains that for the concentration measured on March 11, 2014:

The PM 10 sample on March 11, 2014, at Lamar Municipal of 38 7 μ g/m 3 exceeds the 99th percentile value for all evaluation criteria and is the 3rd largest sample of the dataset and the largest sample in any March. Both samples greater t han the event sample are associated with high wind events. 78

CDPHE explains that for the concentration measured on March 15, 2014:

The PM 10 sample on March 15, 2014, at Lamar Municipal of 17 3 μ g/m 3 exceeds the 99th percentile value for all evaluation criteria and is the 14th largest sample of the dataset. All thirteen samples greater than the event sample are associated with high wind events. 79

CDPHE explains that for the concentration measured on March 18, 2014:

The PM 10 sample on March 18, 2014, at Lamar Municipal of 29 9 μ g/m 3 exceeds the 99th percentile value for all evaluation criteria and is the 6th largest sample of the dataset. The five samples greater than the event sample are associate d with high wind events. 80

CDPHE explains that for the concentration measured on March 29, 2014:

The PM 10 sample on March 29, 2014, at Lamar Municipal of 26 3 μ g/m 3 exceeds the 99th percentile value for all evaluation criteria and is the 8th largest sample of the dataset. The seven samples greater than the event sample are associate d with high wind events. 81

CDPHE explains that for the concentration measured on March 30, 2014:

The PM 10 sample on March 30, 2014, at Lamar Municipal of 26 4 μ g/m 3 exceeds the 99th percentile value for all evaluation criteria and is the 7th largest sample of all samples from 2009

78 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 129.

79 Ibid., 134.

80 Ibid., 139.

81 Ibid., 144.52

through August, 2014. All six samples greater than the event sample are associated with high wind events. 82

CDPHE explains that for the concentration measured on March 31, 2014:

The PM 10 sample on March 31, 2014, at Lamar Municipal of 22 3 μ g/m 3 exceeds the 99th percentile value for all evaluation criteria and is the 10th largest sample of the dataset. The nine samples greater than the event sample are associate d with high wind events. 83

CDPHE explains that for the concentration measured on April 23, 2014:

The PM 10 sample on April 23, 2014, at Lamar Municipal of 35 0 μ g/m 3 exceeds the 99th percentile value for all evaluation criteria and is the 4th largest sample of the dataset. The three samples greater than the event sample are associate d with high wind events. 84

CDPHE explains that for the concentration measured on April 29, 2014:

The PM 10 sample on April 29, 2014, at Lamar Municipal of 32 1 μ g/m 3 exceeds the 99th percentile value for all evaluation criteria and is the 5th largest sample of the dataset. The four samples greater than the event sample are associate d with high wind events. 85

CDPHE explains that for the concentration measured on November 10, 2014:

The PM 10 sample on November 10, 2014, at Lamar Municipal of 298 μ g/m 3 exceeds the 99th percentile value for all evaluation criteria and is the 7th largest sample of the dataset. The six samples greater than the event sample are associate d with high wind events. 86

The EPA “Interim Guidance on High Wind Exceptional Events” recommends that demonstrations also consider percentile ranks when dust impacted data i s excluded. 87 CDPHE States that the percentile rank for these areas is 99% and above for the monitor in question on all nine days in question.

Included with this TSD is an enclosure which analyz es drought conditions in the Lamar area from 1897- 2015, and associates the trends with high wind blow ing dust events. It is titled Analysis of Lamar Drought Condition Severity and Blowing Dust: 1897-2015. The review finds some correlation between prolonged drought (as defined by 7-year annual average) and b lowing dust conditions in Lamar. The enclosure is a t the end of this document.

Since at least 2005 in these areas, values exceedin g the 24-hour PM 10 NAAQS are only found during high wind dust events, including those in 2014. This inf ormation indicates that values at the level seen du ring

82 Ibid., 149.

83 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 154.

84 Ibid., 159.

85 Ibid., 164.

86 Ibid., 169.

87 See “Interim Guidance on the Preparation of Demons trations in Support of Requests to Exclude Ambient Air Quality Data Affected by High Winds Under the Excep tional Events Rule” of May 2013, page 20.53

2014 are extremely rare in the absence of high wind dust exceptional event impacts, and that it is unl ikely that any sources of PM 10 were involved in the 2014 exceedances other than w ind-blown dust. Therefore, the EPA concludes that this event was in excess of HF pursuant to the Treatment of Data Influenced by the EER. Table 13 summarizes the EPA’s evaluation o f CDPHE’s HF EE demonstration.

Table 13: EPA’s Analysis of CDPHE’s TSD of HF
Exceedance Date Exceedance

Location Historical Fluctuations

Demonstration Citation Sufficient Quality of Evidence? EPA Criterion

Met?

March 11, 2014 Lamar Municipal

Building Section 3: p. 129-134 Yes Yes

March 15, 2014 Lamar Municipal

Building Section 3: p. 134-139 Yes Yes

March 18, 2014 Lamar Municipal

Building Section 3: p. 139-144 Yes Yes

March 29, 2014 Lamar Municipal

Building Section 3: p. 144-149 Yes Yes

March 30, 2014 Lamar Municipal

Building Section 3: p. 149-154 Yes Yes

March 31, 2014 Lamar Municipal

Building Section 3: p. 154-159 Yes Yes

April 23, 2014 Lamar Municipal

Building Section 3: p. 159-164 Yes Yes

April 29, 2014 Lamar Municipal

Building Section 3: p. 164-169 Yes Yes

November 10, 2014 Lamar Municipal

Building Section 3: p. 169-174 Yes Yes

Clear Causal Relationship

EPA considers a variety of evidence when evaluating whether there is a Clear Causal Relationship (CCR) between the measurement under consideration and the event that is claimed to have affected the air quality in the area. Demonstrations should include documentation showing that the event in fact occurr ed and that emissions related to the event were transp orted in the direction of the monitor(s) where measurements were recorded; the size of the area af fected by the transported emissions; the relationsh ip in time between the event, transport of emissions, and recorded concentrations; and, as appropriate, pollutant species-specific information supporting a CCR between the event and the measured concentration. 88

Section 2 of CDPHE’s demonstration provides analyse s from NOAA’s National Weather Service (NWS) that demonstrate the existence of high wind blowing dust events originating far southwest or far north of the monitors in question, but including southern Co lorado’s contribution:

88 See “Interim Guidance on the Preparation of Demons trations in Support of Requests to Exclude Ambient Air Quality Data Affected by High Winds Under the Excep tional Events Rule” of May 2013, pages 21-22.54

March 11, 2014:

The National Oceanic and Atmospheric Administration (NOAA) Satellite Services Division was in agreement with the conclusion that blowing dust was occurring in southeast Colorado. The Smoke Text Product from NOAA at 11:00 AM MST on Mar ch 11, 2014 stated:

“Several large plumes of blowing dust/sand were obs erved over southeast Colorado and far western Kansas moving to the south towards the Oklahoma Panhandle.” (Source: http://www.ssd.noaa.gov/PS/FIRE/DATA/SMOKE/2014/201 4C111803.html)

Additionally, the Pueblo office of the National Wea ther Service and the Colorado Department of Public Health and Environment issued Blowing Dust A dvisories for southeast Colorado in anticipation of the blowing dust event of March 11, 2014. Text from these advisories includes:

“Visibilities...will drop to less than 1 mile at time s due to blowing dust...particularly down wind of plowed fields or in areas where vegeta tion growth has been limited by long term drought and soils remain loose.” (Source: http ://mesonet.agron.iastate.edu/wx/afos/)

“People with heart or lung disease, older adults, a nd children in the affected area should reduce prolonged or heavy indoor and outdoor exerti on.” (Source: http://www.colorado.gov/airquality/forecast_archive .aspx?seeddate=03%2f11%2f2014) 89

March 15, 2014:

The National Oceanic and Atmospheric Administration (NOAA) Satellite Services Division was in agreement with the conclusion that blowing dust was occurring in southeast Colorado. The Smoke Text Product from NOAA at 5:45 PM MST on Marc h 15, 2014 stated:

“Strong northerly winds are kicking up dust/sand an d loose soils across much of SE Colorado south of US40 in Lincoln and Cheyenne coun ties where individual narrow N-S bands/plumes consolidated and became moderately to dense sand strom (sic) across E Animas and Baca counties before moving into NM, Tex as county OK and far NW portions of the TX panhandle as far south as I-40 i n Quay county.” (Source: http://www.ssd.noaa.gov/PS/FIRE/DATA/SMOKE/2014/201 4C160051.html)

Additionally, both the Pueblo office of the Nationa l Weather Service and the Colorado Department of Public Health and Environment issued Blowing Dust Advisories for southeast Colorado in anticipation of the blowing dust event of March 15, 2014. Text from these advisories includes:

“A few areas may see visibility near zero in and ar ound exposed fields.” (Source: http://mesonet.agron.iastate.edu/wx/afos/)

“People with heart or lung disease, older adults, a nd children in the affected area should reduce prolonged or heavy indoor and outdoor exerti on.” (Source: http://www.colorado.gov/airquality/forecast_archive .aspx?seeddate=03%2f15%2f2014) 90

89 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 24.

90 Ibid., 34.55

March 18, 2014:

The National Oceanic and Atmospheric Administration (NOAA) Satellite Services Division was in agreement with the conclusion that blowing dust was occurring in southeast Colorado. The Smoke Text Product from NOAA at 9:45 AM MST on Marc h 18, 2014 stated:

“A fairly large area of dust, partially obscured by clouds, was seen moving southsoutheast across southeastern Colorado and extreme southwestern Kansas.” (Source: http://www.ssd.noaa.gov/PS/FIRE/DATA/SMOKE/2014/201 4C181714.html)

Additionally, the Pueblo office of the National Wea ther Service issued a Dust Storm Warning for southeast Colorado while the Colorado Department of Public Health and Environment issued a Blowing Dust Advisory in anticipation of the blowin g dust event of March 18, 2014. Text from these advisories includes:

“Significant amounts of blowing dust will likely oc cur which will reduce visibility to around 1⁄4 mile throughout the day.” (Source: http:// mesonet.agron.iastate.edu/wx/afos/)

“People with heart or lung disease, older adults, a nd children in the affected area should reduce prolonged or heavy indoor and outdoor exerti on.” (Source: http://www.colorado.gov/airquality/forecast_archive .aspx?seeddate=03%2f18%2f2014) 91

March 29, 2014:

The blowing dust of March 29, 2014 was not only obs erved, but also anticipated. The Navy Aerosol Analysis and Prediction System (NAAPS) accu rately forecast that blowing dust would be an issue in southeast Colorado during the late morn ing and afternoon hours. Figure 35 [EPA Figure 33] shows the output from this model coverin g the time period from 18Z (11:00 AM MST), March 29 to 0Z (5:00 PM MST, March 29), March 30. The NAAPS system models blowing dust emissions and transport based on soil moisture content, soil erodibility factors and a variety of meteorological factors known to be condu cive to blowing dust. 92 The forecast panel in the upper left of Figure 35 [EPA Figure 33] clearly shows above normal Total Optical Depth values attributed to dust over southeast Colorado.

Additionally, the Colorado Department of Public Hea lth and Environment (CDPHE) was alerted to blowing dust on March 29, 2014 and consequently issued a Blowing Dust Advisory for most of southeast Colorado. Text from that advisory include s:
“Strong gusty winds will bring a threat for blowing dust to portions of southeastern Colorado.” and, “People with heart or lung disease, older adults, and children in the affected area should reduce prolonged or heavy indo or and outdoor exertion.” (Source: http://www.colorado.gov/airquality/forecast_archive .aspx?seeddate=03%2f29%2f2014) 93

The NAAPS system models blowing dust emissions and transport based on soil moisture content, soil erodibility factors and a variety of meteorological factors known to be conducive to blowing dust. The forecast panel in the lower left of Figure 34 shows an area of highly elevated surface dust concentrat ions over much of New Mexico, and the optical depth pane l on the upper left shows dust continuing over

91 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 44.

92 For a description of NAAPS see: http://www.nrlmry.n avy.mil/aerosol_web/Docs/globaer_model.html

93 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 53.56

southeastern Colorado into Kansas. This model outpu t suggests that this drought-stricken region was a major source region for blowing dust on March 29, 2 014 in Lamar.

Figure 34: National NAAPS Analysis for March 29, 20 14 (CDPHE’s TSD Figure 35) 94

March 30, 2014:

The blowing dust of March 30, 2014 was not only obs erved, but also anticipated. The Navy Aerosol Analysis and Prediction System (NAAPS) accu rately forecast that blowing dust would be an issue in southeast Colorado during the afternoon and evening hours. Figure 48 [EPA Figure 34] shows the output from this model covering the t ime period from 18Z (11:00 AM MST),

94 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 55.57

March 30 to 0Z (5:00 PM MST, March 30), March 31 wh ile Figure 49 shows the same model for the time period of 0Z (5:00 PM MST, March 30), Marc h 31 to 6Z (11:00 PM MST, March 30), March 31. The NAAPS system models blowing dust emis sions and transport based on soil moisture content, soil erodibility factors and a va riety of meteorological factors known to be conducive to blowing dust... The forecast panels in t he upper left quadrant of both EPA Figures 34 and 35 [CDPHE Figures 48 and 49] clearly show To tal Optical Depth values increasing in southeast Colorado to above normal levels. The gree n and yellow shading indicates that those enhanced values are attributed to dust.

Additionally, the Colorado Department of Public Hea lth and Environment (CDPHE) was alerted to blowing dust on March 30, 2014 and consequently issued a Blowing Dust Advisory for most of southeast Colorado. Text from that advisory include s:
“Strong gusty winds will bring a threat for blowing dust to portions of southwestern, southern and southeastern Colorado.” and, “People w ith heart or lung disease, older adults, and children in the affected area should re duce prolonged or heavy indoor and outdoor exertion.” (Source: http://www.colorado.gov/airquality/forecast_archive .aspx?seeddate=03%2f30%2f2014).
95

The NAAPS system models blowing dust emissions and transport based on soil moisture content, soil erodibility factors and a variety of meteorological factors known to be conducive to blowing dust. The forecast panel in the lower left of Figures 35 and 36 shows an area of highly elevated surface dust concentrations over Utah, Arizona, New Mexico, Colo rado, Texas, and Kansas (and continuing northeast) and the optical depth panel on the upper left of Fi gures 32 and 33 show dust at 5 pm over Utah, Arizon a, New Mexico, Colorado, and Texas, moving by 11 PM to wards Kansas, Nebraska, and Wyoming. This model output suggests that this drought-stricken re gion was a major source region for blowing dust on March 30, 2014 in Lamar.

95 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 67.58

Figure 35: National NAAPS Analysis for 5 PM March 3 0, 2014 (CDPHE’s TSD Figure 48) 96

96 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 72.59

Figure 36: National NAAPS Analysis for 11 PM March 30, 2014 (CDPHE’s TSD Figure 49) 97

March 31, 2014:

The blowing dust of March 31, 2014 was not only obs erved, but also anticipated. The Navy Aerosol Analysis and Prediction System (NAAPS) accu rately forecast that blowing dust would be an issue in southeast Colorado during the morning h ours of March 31. Figure 60 [EPA Figure 36] shows the output from this model covering the time period from 6Z (11:00 PM MST, March 30), March 31 to 12Z (5:00 AM MST), March 31 while Figur e 61 [EPA Figure 37] shows the same model for the time period of 12Z (5:00 AM MST), Mar ch 31 to 18Z (11:00 AM MST), March 31.

97 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 73.60

The NAAPS system models blowing dust emissions and transport based on soil moisture content, soil erodibility factors and a variety of meteorolo gical factors known to be conducive to blowing dust. The forecast panels in the upper left of both Figure 60 and Figure 61 [EPA Figures 36 and 37] clearly show Total Optical Depth values in sout heast Colorado above normal levels. The green and yellow shading indicates that those enhan ced values are attributed to dust.

Additionally, the Colorado Department of Public Hea lth and Environment (CDPHE) was alerted to the threat for blowing dust on March 31, 2014 an d consequently issued a Blowing Dust Advisory for most of southeast Colorado, including the Lamar area. Text from that advisory included: “Strong gusty winds will bring a threat for blowing dust to large portions of eastern Colorado.” and, “People with heart or lung disease, older adults, and children in the affected area should reduce prolonged or heavy indo or and outdoor exertion.” (Source: http://www.colorado.gov/airquality/forecast_archive .aspx?seeddate=03%2f31%2f2014 ).

98

The NAAPS system models blowing dust emissions and transport based on soil moisture content, soil erodibility factors and a variety of meteorological factors known to be conducive to blowing dust. The optical depth panel on the upper left of Figures 37 and 38 show dust at 5 AM over Arizona, New Mexico, Colorado, Texas, Oklahoma, Kansas, Nebraska, and Wy oming, and then moving northwest by 11 AM. This model output suggests that this drought-stric ken region was a major source region for blowing du st on March 31, 2014 in Lamar.

Figure 37: National NAAPS Analysis for 5 AM March 3 1, 2014 (CDPHE’s TSD Figure 60) 99

98 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, pages 85-86.

99 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 86.61

Figure 38: National NAAPS Analysis for 11 AM March 31, 2014 (CDPHE’s TSD Figure 61) 100

100 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 87.62

April 23, 2014:

Radar imagery provides strong supporting evidence t hat a regional dust storm was taking place on April 23, 2014. The Pueblo radar image at 6:14 PM M ST, April 23 (Figure 72) [EPA Figure 38] shows a suspected line of dust (circled in red) app roaching Lamar and La Junta from the north. This band of blowing dust was likely produced by se veral factors; including the cold front passage described earlier combined with strong outf low winds from post-frontal thunderstorms which were impacting northeast Colorado. Figure 73 [EPA Figure 40] displays the 1-km radar mosaic from the central Rockies at 4:25 PM MST and shows one particularly intense thunderstorm in northeast Colorado (circled in red) with discernible areas of outflow visible to its south (green arrow). These areas of outflow would c ontinue to move southward and remained intact nearly two hours later in Figure 72 [EPA Fig ure 39]. Also note that the radar return from63

Figure 72 [EPA Figure 39] has a distinct bow echo p attern which is often associated with strong, sometimes damaging, winds that spread outward from the bottom of storms. 101

Figure 39: National NAAPS Analysis for 11 AM March 31, 2014 (CDPHE’s TSD Figure 72) 102

Figure 40: National NAAPS Analysis for 11 AM March 31, 2014 (CDPHE’s TSD Figure 73) 103

101 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 100.

102 Ibid., 101.

103 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 101.64

April 29, 2014:

The National Oceanic and Atmospheric Administration (NOAA) Satellite Services Division was in agreement with the conclusion that blowing dust was occurring in eastern Colorado. The Smoke Text Product from NOAA at 7:00 PM MST on Apri l 29, 2014 stated:

“An expansive area of dust is moving from the centr al plains south into the Texas Panhandle this evening. Through sunset, the dust is seen reaching from eastern Colorado down through central Texas.” (Source: http://www.ssd.noaa.gov/PS/FIRE/DATA/SMOKE/2014/201 4D300316.html)

Additionally, the Pueblo office of the National Wea ther Service issued a Dust Storm Warning for southeast Colorado while the Colorado Department of Public Health and Environment issued a Blowing Dust Advisory in anticipation of the blowin g dust event of April 29, 2014. Text from these advisories includes:

“Wrap around north flow around a deep storm system over the upper Midwest will produce high winds and widespread blowing dust thro ugh this afternoon.” (Source: http://mesonet.agron.iastate.edu/wx/afos/)

“Extremely gusty winds will produce areas of blowin g dust to portions of eastern Colorado for much of Tuesday.” (Source:65 http://www.colorado.gov/airquality/forecast_archive .aspx?seeddate=04%2f29%2f2014 )

104

November 10, 2014:

The National Oceanic and Atmospheric Administration (NOAA) Satellite Services Division and the National Weather Service (NWS) office in Pueblo were in agreement with the conclusion that blowing dust was occurring in southeast Colorado. T he Smoke Text Product from NOAA at 7:45 PM MST on November 10, 2014 stated:

“There is a large and significant area of blowing d ust that can be seen moving towards the south/southeast across southeastern Colorado an d into northeastern New Mexico.” (Source: http://www.ssd.noaa.gov/PS/FIRE/DATA/SMOKE /2014/2014K110313.html)

While the NWS Forecast Discussion at 3:50 PM MST st ated:

“Arctic front came through the eastern plains this afternoon...in typical fashion...ahead of schedule. 50-60 mph N to NE wind gusts along and be hind FROPA...with blowing dust.” (Source: http://mesonet.agron.iastate.edu/wx/afos/)

Additionally, the Colorado Department of Public Hea lth and Environment (CDPHE) issued a Blowing Dust Advisory for southeast Colorado, inclu ding Lamar, at 1:00 PM MST. Included in the advisory text:

“Strong gusty winds with a cold front will create a reas of blowing dust through Monday evening.” (Source: http://www.colorado.gov/airquality/forecast_archive .aspx?seeddate=11%2f10%2f2014)

105

CDPHE generally summarizes that:

The PM 10 exceedances in Lamar would not have occurred if no t for the following: (a) dry soil conditions over source regions with 30-day precipit ation totals below the threshold identified as a precondition for blowing dust; and (b) meteorologic al conditions that caused strong surface winds over the area of concern. Surface weather observati ons provide strong evidence that dust storms took place on March 11, 2014, March 15, 2014, March 18, 2014, March 29, 2014, March 30, 2014, March 31, 2014, April 23, 2014, April 29, 201 4, and November 10, 2014. The meteorological conditions during these events in 20 14 caused regional surface winds over 30 mph with gusts exceeding 40 mph. These speeds are above the thresholds for blowing dust identified in EPA draft guidance and in detailed analyses comp leted by the State of Colorado. 106

EPA concludes that there was a CCR for these events pursuant to the Treatment of Data Influenced by th e EER. Table 14 summarizes the EPA’s evaluation of CD PHE’s CCR EE demonstration.

104 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 112.

105 Ibid., 125.

106 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 221.66

Table 14: EPA’s Analysis of CDPHE’s TSD of CCR 107 Exceedance Date Clear Causal Relationship Demonstration Citation Sufficient Quality of Evidence? EPA Criterion

Met?

March 11, 2014 Section 2: p. 24 Yes Yes

March 15, 2014 Section 2: p. 34 Yes Yes

March 18, 2014 Section 2: p. 44 Yes Yes

March 29, 2014 Section 2: p. 53-55 Yes Yes

March 30, 2014 Section 2: p. 69-73 Yes Yes

March 31, 2014 Section 2: p. 85-87 Yes Yes

April 23, 2014 Section 2: p.100-101 Yes Yes

April 29, 2014 Section 2: p. 112 Yes Yes

November 10, 2014 Section 2: p. 125 Yes Yes

Affects Air Quality (AAQ)

As stated in EPA’s Interim Guidance for High Wind E xceptional Events Section 3.4, EPA will consider events to have affected air quality if the CCR and HF requirements have been adequately demonstrated. The information presented in the HF and CCR demonst rations on the preceding three pages of this (EPA’s) TSD are cited in Table 15. Additionally, CD PHE states that:

Since at least 2005, there has not been an exceedan ce that was not associated with high winds carrying PM 10 dust from distant sources in these areas. This is evidence that the events were associated with a measured concentration in excess of normal historical fluctuations including background

. 108

Therefore, the EPA concludes that this event Affect ed Air Quality pursuant to the Treatment of Data Influenced by high wind under the EER. Table 15 sum marizes the EPA’s evaluation of CDPHE’s AAQ EE demonstration.

107 See “Interim Guidance on the Preparation of Demons trations in Support of Requests to Exclude Ambient Air Quality Data Affected by High Winds Under the Excep tional Events Rule” of May 2013 page 21.

108 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 221.67

Table 15: EPA’s Analysis of CDPHE’s TSD of AAQ
Exceedance Date HF and

CCR Affects Air Quality

Demonstration Citation Sufficient Quality of Evidence EPA

Criterion Met?

March 11, 2014 HF Section 3: p. 129-134 Yes Yes

CCR Section 2: p. 24 Yes Yes

March 15, 2014 HF Section 3: p. 134-139 Yes Yes

CCR Section 2: p. 34 Yes Yes

March 18, 2014 HF Section 3: p. 139-144 Yes Yes

CCR Section 2: p. 44 Yes Yes

March 29, 2014 HF Section 3: p. 144-149 Yes Yes

CCR Section 2: p. 53-55 Yes Yes

March 30, 2014 HF Section 3: p. 149-154 Yes Yes

CCR Section 2: p. 69-73 Yes Yes

March 31, 2014 HF Section 3: p. 154-159 Yes Yes

CCR Section 2: p. 85-87 Yes Yes

April 23, 2014 HF Section 3: p. 159-164 Yes Yes

CCR Section 2: p.100-101 Yes Yes

April 29, 2014 HF Section 3: p. 164-169 Yes Yes

CCR Section 2: p. 112 Yes Yes

November 10, 2014 HF Section 3: p. 169-174 Yes Yes

CCR Section 2: p. 125 Yes Yes

Natural Event

As stated in EPA’s Interim Guidance for High Wind E xceptional Events Section 6.3.6, EPA will consider an event to be a natural event if both the nRCP and CCR requirements have been adequately demonstrated. CDPHE states that:68

Due to the semi-arid nature of parts of the state, Colorado is highly susceptible to windblown dust events. These events are often captured by various air quality monitoring equipment throughout the state, sometimes resulting in exceedances or vi olations of the 24-hour PM 10 NAAQS. This document contains detailed information about the la rge regional windblown dust events that occurred in 2013. The Colorado Department of Public Health and Environment (CDPHE) Air Pollution Control Division (APCD) has prepared this report for the U.S. Environmental Protection Agency (EPA) to demonstrate that the ele vated PM 10 concentrations recorded in 2014 in Lamar, Colorado, were caused by natural events

. 109

CDPHE has sufficiently demonstrated the CCR and nRC P requirements for the 2014 events. Therefore, the EPA concludes that these were natural events pu rsuant to the Treatment of Data Influenced by high winds under the EER. Table 16 summarizes the EPA’s evaluation of CDPHE’s Natural Event EE demonstration.

Table 16: EPA’s Analysis of CDPHE’s TSD of Natural Event

Exceedance Date nRCP or CCR Natural Event Demonstration Citation Sufficient

Quality of Evidence? EPA

Criterion Met?

March 11, 2014 nRCP- Anthropogenic Section 5: p. 182-220 Yes Yes

nRCP-Wind Speed Section 2: p. 14-27 Yes Yes

CCR Section 2: p. 24 Yes Yes

March 15, 2014 nRCP- Anthropogenic Section 5: p. 182-220 Yes Yes

nRCP-Wind Speed Section 2: p. 28-37 Yes Yes

CCR Section 2: p. 34 Yes Yes

March 18, 2014 nRCP- Anthropogenic Section 5: p. 182-220 Yes Yes

nRCP-Wind Speed Section 2: p. 38-47 Yes Yes

CCR Section 2: p. 44 Yes Yes

March 29, 2014 nRCP- Anthropogenic Section 5: p. 182-220 Yes Yes

nRCP-Wind Speed Section 2: p. 48-57 Yes Yes

CCR Section 2: p. 53-55 Yes Yes

109 “TSD for the 2014 Lamar Exceptional Events,” May 7, 2015, page 1.69

Table 16 (cont.): EPA’s Analysis of CDPHE’s TSD of Natural Event

Exceedance Date nRCP or CCR Natural Event Demonstration Citation Sufficient

Quality of Evidence? EPA

Criterion Met?

March 30, 2014 nRCP- Anthropogenic Section 5: p. 182-220 Yes Yes

March 30, 2014 nRCP- Anthropogenic Section 5: p. 182-220 Yes Yes

nRCP-Wind Speed Section 2: p. 58-75 Yes Yes

CCR Section 2: p. 69-73 Yes Yes

March 31, 2014 nRCP- Anthropogenic Section 5: p. 182-220 Yes Yes

nRCP-Wind Speed Section 2: p. 76-89 Yes Yes

CCR Section 2: p. 85-87 Yes Yes

April 23, 2014 nRCP- Anthropogenic Section 5: p. 182-220 Yes Yes

nRCP-Wind Speed Section 2: p. 90-102 Yes Yes

CCR Section 2: p.100-101 Yes Yes

April 29, 2014 nRCP- Anthropogenic Section 5: p. 182-220 Yes Yes

nRCP-Wind Speed Section 2: p. 103-115 Yes Yes

CCR Section 2: p. 112 Yes Yes

November 10, 2014 nRCP- Anthropogenic Section 5: p. 182-220 Yes Yes

nRCP-Wind Speed Section 2: p. 116-128 Yes Yes

CCR Section 2: p. 125 Yes Yes

No Exceedance or Violation But For the Event

Generally, the No Exceedance or Violation But for t he Event (NEBF) demonstration is similar to the demonstration of the nRCP and CCR requirements, and should show that the measured concentration would have been below the applicable NAAQS without the effects of the events.70

CDPHE provides a summary of the analysis and inform ation presented in the demonstration that show both the nRCP and CCR requirements have been met an d states that:



### Both wind speeds and soil moisture in surrounding a reas were conducive to the generation of significant blowing dust. Multiple so urces of data for the events in question and analyses of past dust storms in this area prove that these were natural events and, more specifically, significant natural dust storms originating outside the monitored areas. “But for” the large regional dust storms on March 1 1, 2014, March 15, 2014, March 18, 2014, March 29, 2014, March 30, 2014, March 31, 201 4, April 23, 2014, April 29, 2014, and November 10, 2014, these exceedances would not have occurred. 110

Therefore, the EPA concludes that there would have been NEBF pursuant to the Treatment of Data Influenced by high winds under the EER. While not e xplicitly stated in the documentation, EPA notes that PM 10 concentrations before the periods of high winds on the event days were all well below the 24- hour PM 10 NAAQS of 150 ug/m 3 , providing further support for CDPHE’s conclusion. Table 17 summarizes the EPA’s evaluation of CDPHE’s NEBF EE demonstration.

Table 17: EPA’s Analysis of CDPHE’s TSD of NEBF Exceedance Date No Exceedance But For the Event Demonstration Citation Sufficient Quality of Evidence? EPA Criterion

Met?

March 11, 2014 Section 6: p. 221 Yes Yes

March 15, 2014 Section 6: p. 221 Yes Yes

March 18, 2014 Section 6: p. 221 Yes Yes

March 29, 2014 Section 6: p. 221 Yes Yes

March 30, 2014 Section 6: p. 221 Yes Yes

March 31, 2014 Section 6: p. 221 Yes Yes

April 23, 2014 Section 6: p. 221 Yes Yes

April 29, 2014 Section 6: p. 221 Yes Yes

November 10, 2014 Section 6: p. 221 Yes Yes

Schedule and Procedural Requirements

In addition to technical demonstration requirements , 40 CFR 50.14(c) specifies the schedule and procedural requirements an air agency must follow t o request data exclusion. CDPHE received no

110 “TSD for the 2014 Lamar Exceptional Events,” May 7 , 2015, page 221.71

external comments during the 30 day comment period, but minor corrections were made to the report based on internal staff review. Table 18 outlines E PA’s evaluation of these requirements.

Table 18: EPA’s Analysis of Schedules and Procedura l Criteria Reference Schedules and Procedural Criteria Demonstration Citation EPA

Criterion Met?

Did the State provide prompt public notification of the event? 40 CFR 50.14(c)(1)(i) Section 1: p.12 Yes

Were flags and initial description placed on the data by July 1 st of the following year? 40 CFR 50.14(c)(2)(iii) Section 1: p.12-13 Yes

Was the demonstration submitted within 3 years of the end of the quarter in which the event occurred and 12 months prior to the date that any regulatory decision must be made by EPA? 40 CFR 50.14(c)(3)(i) May 7, 2015 Yes

Was the public comment process followed and documented? 40 CFR 50.14(c)(3)(v) Section 1: p.13 Yes



## CONCLUSION

EPA has reviewed documentation provided by CDPHE to support claims that dust emissions generated by high winds resulted in PM 10 transport from arid regions in Colorado, Arizona, New Mexico, western Texas, Wyoming, Nebraska, and western Kansas into t he Lamar area during 2014. These high wind events caused exceedances of the 24-hour PM 10 NAAQS at the location identified in Table 1 of this document on March 11, March 15, March 18, March 29, March 30, March 31, April 23, April 29 and November 10, 2014, in Lamar. EPA concurs that the f lagged exceedances at the Lamar monitor on these days meet the definition of an exceptional event: t he events affected air quality, were nRCP, and met the definition as natural events. Specifically, EPA has determined that the event was nRCP due to high win d conditions that transported PM 10 from sources outside of the immediate Lamar area an d also subsequently may have overwhelmed some reasonable controls withi n Lamar. Also, regardless of transport into the area, information pertaining to the controls implem ented within the affected area, the spatial extent of elevated PM 10 concentrations measured in the area, and the wind s peeds associated with the high wind dust events provide sufficient evidence to conclude that this event was nRCP. Furthermore, EPA has determined that there is a CCR between the event an d the measured exceedance, there would have been NEBF, and the measured exceedances are in excess of normal HFs.72

EPA finds that the weight of evidence is sufficient to concur on the flagging of the data for the 24-h our PM 10 NAAQS exceedance of 387 μ g/m 3 at the Lamar Power Plant monitor on March 11, 173 μ g/m 3 on March 15, 299 μ g/m 3 on March 18, 263 μ g/m 3 on March 29, 264 μ g/m 3 on March 30, 223 μ g/m 3 on March 31, 350 μ g/m 3 on April 23, 321 μ g/m 3 on April 29, and 298 μ g/m 3 on November 10, 2014.

This concurrence does not constitute final EPA acti on regarding any matter on which EPA is required to provide an opportunity for public comment. In parti cular, this applies to determinations regarding the attainment status or classification of the area. Fi nal actions will take place only after EPA complete s notice and comment rulemaking on those determinatio ns.