# Technical Support Document

for the Proposed Rulemaking Action on the Coachella Valley

2007 8

- Hour Ozone Plan

Air Division U.S. EPA Region 9 September 20162

1. Introduction

2. Requirements for Air Quality Modeling

3 . Air Quality Modeling and Other Analyses in the 2007 AQMP

A. Air Quality Modeling Requirements.

B. Modeled Attainment Test for Ozone

- Projected Ozone Air Quality for the Coachella Valley Non

- attainment Area

4 . Weight of Evidence

A. Air Quality Modeling and Other Analyses in the 2012 AQMP

B. Air Quality Monitoring data for the Coachella Valley

5 . Evaluation and Conclusion3

1. Introduction

This document provides supporting information and analysis for EPA ’ s proposed rulemaking

action o n the attainment demonstration contained in the State Implementation Plan (SIP) for the Coachella Valley 1997 8

- hour ozone nonattainment area. The attainment demonstration , part of the larger SIP submittal, is contained in the South Coast Air Quality Manag ement District‘s (SCAQMD) “ 2007 Air Quality Management Plan

, ” June 2007 (2007 AQMP) at chapter s 5 and 8 and Appendix V . This document also : describes the Clean Air Act (CAA) requirements for an attainment demonstration and EPA ’ s regulations and policies interpreting the CAA requirements ; summari zes portions of the 2007 AQMP that address CAA requirements , regulations and policies; and presents EPA ’ s evaluation of whether the State ’ s submittals meet these requirements. In preparing this document, EPA review ed the attainment demonstration in the 2007 AQMP in support of the final rule

, 1 and this document refers to the technical support

document for that action.

2 . Requirements for Air Quality Modeling

CAA section 172(c)(1) requires states to submit a plan t hat “ shall provide for attainment of the national primary ambient air quality standards. ” The Act requires SIPs for nonattainment areas to

demonstrate that the area will attain the 8

- hour ozone standard as expeditiously as practicable,

but no later than the outside dates established by the Act. The Phase 2 Rule provides timing and guidance for this requirement for the 1997 8

- hour ozone standard and identifies the modeling guidance available to make the demonstration. 2 “ Severe

- 15 ” 1997 8

- hour ozone nonatta inment

areas must attain the stan dard no later than June 15, 2019

. 3 An attainment demonstration SIP must include technical analyses to locate and identify sources of emissions that are causing violations of the NAAQS within nonattainment areas

, adopted mea sures with schedules for implementation and other means and techniques necessary and appropriate for attainment

, and contingency measures required under section 172(c)(9) of the Act that can be implemented without further action by the State or the Adminis trator to cover failures to meet RFP milestones

and/or attainment. For any ozone nonattainment area classified as serious or above, section 182(c)(2)(A) of the CAA specifically requires the State to submit a modeled attainment demonstration based on a phot ochemical grid modeling evaluation or any other analytical method determined by the Administrator to be at least as effective as photochemical modeling.

T he attainment demonstration requirement is a continuing applicable requirement for the

Coachella Vall ey under the EPA’s anti

- backsliding rules. See 40 CFR 51.1105(a)(1) and 51.1100(o)(12). EPA has issued guidance 4 describ ing the criteria that an air quality model and application should meet to qualify for use in an 8

- hour ozone attainment demonstration.

1 Air Quality State Implementation Plans; Approvals and Promulgations: California; South Coast 1

- Hour and 8

- Hour Ozone

, 79 FR 52526 (September 3, 2014 )

. 2 “Final Rule to Implement the 8

- Hour Ozone National Ambient Air Quality Standard

– Phase 2

, ” 70 FR 71612 ( November 29, 2005)

. 3 While the attainment date is not later than June 15, 2019, EPA ’s determination of attainment w ill be based on the ozone season immediately preceding that date , meaning no later than 2018.

4 “ Guidance on the Use of Models and Other Analyses for Demonstrating Attainment of Air Quality Goals for Ozone, PM2.5, and Regional Haze,” EPA

- 454/B

- 07

- 002, April 2007 (“Modeling G uidance”).4

As with any predictive tool, there are inherent uncertainties associated with photochemical modeling. EPA ’ s guidance recognizes these limitations and provides approaches for considering other analytical evidence to help assess whether attainment of the NAAQS is likely. This process

is called a Weight of Evidence ( WOE ) analysis . EPA ’ s m odeling guidance descri be s the importance of conducting a WOE analysis to determine whether an area is likely to achieve timely attainment, and strongly recommends that all attainment demonstrations include supplemental analyses beyond the recommended modeling. 5 These supplemental analyses provide additional information such as emissions and air quality trends and monitoring data analyses, which strengthen the overall conclusion from the photochemical modeling. A WOE analysis is specifically recommended to be included as part of an y attainment demonstration SIP where the modeling results predict f uture d esign v alues ranging from 82 parts per billion (ppb) to less than 88 ppb. 6

EPA has reviewed and evaluated the air quality modeling used as a basis for the attainment

demonstration i n the 2007 AQMP. T he SCAQMD completed a more recent attainment

demonstration for EPA’s 1

- hour and 1997 8

- hour ozone standard in its “ Final 2012 Air Quality Management Plan, ” February 201 3 ( “ 2012 AQMP ” ); however, that document states that “the 2007 AQMP adequately addressed and satisfied the CAA planning requirements for ozone in the Coachella Valley, and this chapter [Chapter 7: Current & Future Air Quality

– Desert Nonattainment Areas] is for information only.” EPA is consider ing the atta inment demonstration in the 2012 AQMP as part of a WOE analysis. EPA is also consider ing a ir quality monitoring data for the Coachella Valley from 2003 through 2015 as part of this analysis

.

3

. Ai r Quality Modeling in the 2007 AQMP

A. Model Performance

EPA g uidance lists key elements that should be discussed in an attainment demonstration

. 7 EPA’s review of these elements is discussed in detail in the Technical Support Document for the Proposed Rulemaking Action on the South Coast 2007 8

- Hour Ozone Plan and the South Coast Portions of the Revised 2007 State Strategy. 8 There, EPA found the model application to be acceptable for the South Coast Air Basin portion of the 2007 AQMP. The modeling for the Coachella Valley attainment demonstration uses the same modeling approach as was used for the South Coast attainment demonstration, which was based on an air quality modeling domain that covers the entire South Coast Basin, the Coachella Valley, and much of southern California. The air quality model, meteo rological model, domain size, spatial resolution, initial and boundary conditions selection, which were appropriate for that application, are also be appropriate in the adjacent Coachella Valley. The air quality model performance for the plan met EPA goals for the South Coast Air Basin. The Coachella Valley portion of the modeling domain is adjacent to the South Coast Air Basin portion of the domain, and ozone formation and transport is similar to the

5 Modeling Guidance , page 98.

6 Modeling Guidance , page 17.

7 Modeling Guidance

, p age, 134.

8 “Technical Support Document for the Proposed Rulemaking Action on the South Coast 2007 8

- Hour Ozone Plan

and the South Coast Portions of the Revised 20 07 State Strategy Air Division,” U.S. EPA Region 9, September 6,

2011.5

formation in the eastern part of the South Coast Air Bas in. Therefore, EPA believes the model performance for the domain, including the Coachella Valley, is adequate.

Therefore, EPA believes, based on the review and approval of the modeling and key modeling elements from the 2007 AQMP, the modeling is acceptab le as a basis for the attainment demonstration for the Coachella Valley portion of the domain.

B. Modeled Attainment Test for Ozone

- Projected Ozone Air Quality for the Coachella Valley

Nonattainment Area

Modeling simulations were conducted for the base year emission scenarios ( 20 02 ), and future year controlled scenarios (2017). 9 The results of these scenarios are presented i n Table V

- 4

- 17 of

the 2007 AQMP

, reproduced below as Table 1

. The attainment demonstration s hows that both Indio and Palm Springs will meet the federal standard in 2017

.

T able 1 : 2017 Projected Coachella Valley 8

- Hour Ozone Design Values 10

Site 2002

Weighted Design ( ppb ) 2002

Baseline

Simulation (ppb) 2017

Controlled Average (ppb ) Number of

valid days Relative

Reduction

Factor 2024

Controlled Design (ppb) Palm Springs 105.7 99.9 75.9 9 0.767 81.1

Indio 95.0 84.0 66.2 5 0.791 75.2

4

. Weight of Evidence

A

. Air Quality Modeling in the 2012 AQMP

The 2012 AQMP was not a required CAA State Implementation Plan submittal for the 1997 ozone standard. In explaining the reason for the update, the plan explains the difficulty of meeting the 1997 standard by 2023 in the South Coast Air Basin, noting that the 2012 plan will update emission red uction commitments and control strategies. 11 It also states:

Since the Coachella Valley is not in attainment of the federal 8

- hour ozone standards, this chapter will address the current status of ozone air quality and provide the latest projections of future ozone levels, based on the latest emissions inventories and modeling

efforts. 12

As previously noted, the Coachella Valley portion of the 2012 AQMP was provided for informational purposes, not as an update the 2007 AQMP. Therefore, the EPA is conside ring the 2012 AQMP as a supplement to the 2007 AQMP in our WOE analysis of whether the area would

9 2007 AQMP

, Appendix V, page V

- 4

- 52 2007

. 10 2007 AQMP, Appendix V, Table V

- 4

- 17

. 11 2012 AQMP, page ES

- 2.

12 2012 AQMP, page 7

- 1.6

attain the standard by the attainment date. The 2012 AQMP, which has the benefit of more recent emissions budgets and projected emission estimates over a shor ter time span, confirmed that the air quality in the Coachella Valley continues to make progress toward attainment by the area’s 2019 attainment date. Appendix V of the 2012 AQMP projects attainment by the June 15, 2019. The 2012 AQMP no longer projects at tainment in 2017, but in 2018, stating:

The results of the ... 8

- hour ozone simulations conducted for 2014 and 2019 also indicate that the two Coachella sites, Palm Springs and Indio will meet the federal standard by the 2019 attainment date. The projected 2018 8

- hour ozone design for the Coachella Valley portion of the Salton Sea Air Basin will be 84 ppb. 13

B

. Air Quality Monitoring data for the Coachella Valley

EPA has reviewed the most recent air quality monitoring data for the two air quality monitorin g sites in the Coachella Valley. 14 The data, present ed in Figure 1 and listed in T able 2 , indicate that

the 8

- hour ozone design value for 2013

- 2015 for the Indio site is 82 ppb , which is below the 8

- hour ozone NAAQS. The 8

- hour ozone design value for 2013

- 2015 for the Palm Springs site is

88 ppb , which is slightly above the 8

- hour ozone NAAQS. Because t he design value is close to the standard, and there has been a consistent downward trend of the ozone design values at this site, EPA believe s the data for this site is consistent with modeled results which show that the area will attain the standard by the attainment date. EPA believes the most recent ambient data support the modeling which show s that the area will achiev e attainm ent of the 8

- hou r standa rd by the attainment date.

13 2012 AQMP, Appendix V, page V

- 7

- 27.

14 Air Quality Subsystem (AQS) Preliminary Design Value Report, dated September 7, 2016

, for the Coachella Valley and Western Mojave Desert7

Figure 1: 8

- Hour ozone Design Values for the Coachella Valley (ppm)

Table 2: 8

- Hour ozone Design Values for the Coachella Valley (ppm)

Site 2003

-

2005 2004

- 2006 2005

- 2007 2006

- 2008 2007

- 2009 2008

- 2010 2009

- 2011 2010

- 2012 2011

- 2013 2012

- 2014 2013

- 2015

Indio 0.0 95 0.0 90 0.0 88 0.0 86 0.0 86 0.0 85 0.0 84 0.0 84 0.0 85 0.0 84 0.0 82

Palm Springs 0. 104 0. 102 0. 101 0. 97 0.0 96 0.0 95 0.0 93 0.0 92 0.0 92 0.0 91 0.0 88

5

. Evaluation and Conclusion

As part of the 2007 AQMP, t he modeling used for the attainment demonstration was made available to the public for comment, and was subject to public hearing. 15 The air quality modeling documentation in Appendix V of the 2007 AQMP contains all the elements required by EPA ’ s modeling g uidance , and is based on the best and most current information available at

the time the 2007 AQMP was developed. EPA believes that t he available modeling, evidence, analyses, monitoring data, and additional information

, support , when taken together, suppo rt the

conclusion that the Coachella area will reach attainment of the 1997 8

- hour ozone standard by its

attain ment date of June 15, 2019 . The modeling shows significant reductions in ozone from the base period. The modeling predicts values below the 1997 8

- hour ozone standard at the two ozone monitoring stations. The more recent modeling, included as weight of evidence, is

consistent with attainment. With the attainment date so near, EPA has also heavily weighed the

most recent ambient data indicat ing that the area is on a track to achiev e attainment of the 8

- hour standard by June 15, 20 19 . Taking these factors together, we beli eve the modeling and WOE are

consistent with att ainment.

Based on our evaluation, discussed above, we propose to find that the modeling analysis used for

the attainment demonstration in the 2007 AQMP meets the CAA section 172(c)(1) requirement that the plan provide for attainment of the national primary ambient air quality standards at the time of its submittal in 2007, and that the modeling in the 2007 AQMP provide s an adequate basis for the reasonably available control measure, reasonable further progress, and attainm ent
demonstrations in the 2007 8

- Hour Ozone Plan

.

15 The docket for EPA’s action includes proof of publication for the start of the public notice for the 2007 AQMP on Mach 2, 2007 and a public hearing on June 1, 2007.