Memorandum
To: 		Indian Wells Second Maintenance Plan, Docket ID EPA-R09-OAR-2021-0549
From: 		Karina OConnor, Air Planning Office, EPA Region 9
Date: 		February 4, 2021
RE: 	Adequacy Documentation for Plan Motor Vehicle Emission Budgets in the Indian Wells Second PM10 Maintenance Plan 
Attached to this memorandum is the adequacy documentation for the motor vehicle emission budgets in the Indian Wells Valley Second 10-Year PM10 Maintenance Plan (May 7, 2020) ("Indian Wells Second Maintenance Plan").
On July 30, 2020, the California Air Resources Board (CARB) submitted the Indian Wells Second Maintenance Plan to the EPA as a revision to the California SIP. The Indian Wells Second Maintenance Plan includes motor vehicle emissions budgets (MVEBs or "budgets") for 2020 and 2025 milestone years. The budgets reflect existing control measures that have already been adopted and implemented. The budgets are shown in Table 1.
Table 1. Transportation Conformity Budgets for the PM10 NAAQS for the Indian Wells Valley PM10 Area (tons per day, annual average)
Source Category
                                     2020
                                     2025
Vehicular Exhaust, Tire, and Brake Wear[a]
                                     0.04
                                     0.04
SAFE Rule Adjustment
                                     0.00
                                     0.00
Re-Entrained Paved Road Dust
                                     0.11
                                     0.12
Re-Entrained Unpaved Road Dust
                                     0.13
                                     0.13
Road Construction Dust
                                     0.03
                                     0.10
                                                                 Safety Margin:
                                      0.0
                                     0.10
                                                                      Total[b]:
                                     0.31
                                     0.49
                                              Motor Vehicle Emission Budget[c]:
                                     0.40
                                     0.50
              [a] This reflects the adjustment factor for the Safer Affordable Fuel-Efficient (SAFE) Vehicle Rule part one (84 FR 51310, September 27, 2019) using EMFAC2017.
              [b] Values from CEPAM v1.00 may not add up due to rounding.
              [c] Motor Vehicle Emission Budgets calculated are rounded up to the nearest tenth of a tpd.
              Source: Indian Wells Second Maintenance Plan, Table 5.

While adequacy and approval are two separate actions, reviewing the budgets in terms of the adequacy criteria informs the EPA's decision to propose to approve the budgets. For budgets to be approvable, they must meet, at a minimum, the EPA's adequacy criteria (40 CFR § 93.118(e)(4)) to be approvable under all pertinent SIP requirements. To meet these requirements, the budgets must be consistent with the applicable maintenance requirements and reflect all of the motor vehicle control measures contained in the maintenance demonstration. In the Federal Register notice associated with this document, EPA is announcing that the adequacy process for these budgets begins and the public has 30 days to comment on their adequacy, per the transportation conformity regulation at 40 CFR 93.118(f)(2)(i) and (ii). Table 2 below contains our analysis of the budgets in the Indian Wells Second Maintenance Plan for each of the adequacy criteria. Based on the documentation and explanation provided in Table 2, we preliminarily conclude that the Indian Wells Second Maintenance Plan's motor vehicle emission budgets are consistent with the maintenance demonstration, are clearly identified and precisely quantified, and meet all other applicable statutory and regulatory requirements, including the adequacy criteria in 40 CFR § 93.118(e)(4).

Table 2. Evaluation of the Motor Vehicle Emissions Budgets in the Indian Wells Second Maintenance Plan for the 1987 PM10 NAAQS
                           Adequacy Review Criteria
                                40 CFR part 93
             Reference in the Indian Wells Second Maintenance Plan
                                   Citation
                                  Requirement
                            Is Criterion Satisfied?

§ 93.118(e)(4)(i)
The plan was endorsed by the Governor (or designee) and was subject to a public hearing.
                                       Y
The transmittal letter dated July 23, 2020 submitting the Indian Wells Valley Second 10-Year PM10 Maintenance Plan (Indian Wells Second Maintenance Plan) was sent by the Executive Officer of the California Air Resources Board (CARB), Richard W. Corey, the Governor's designee. The transmittal letter indicates that the CARB formally adopted the plan on June 25, 2020 through a Board Resolution (20-18). The local air district (Eastern Kern Air Pollution Control District (EKAPCD)) released its draft plan on April 1, 2020 and requested that public comments be received prior to or at their Board adoption hearing. The District Board hearing was held on May 7, 2020. CARB issued the public notice on May 22, 2020 and requested public comments at or before the public hearing held on June 25, 2020.
§ 93.118(e)(4)(ii)
The plan was developed through consultation with federal, state, and local agencies; full implementation plan documentation was provided and EPA's stated concerns, if any, were addressed.
                                       Y
Consultation with federal, state, and local agencies was undertaken. The consultation process, including the conformity budgets, occurred throughout 2019 and early 2020 via meetings between EPA, CARB, and EKAPCD staff in consultation with KCOG staff. On January 23, 2020, via email from Nesamani Kalandiyur, the EPA received a copy of the draft Indian Wells Second Maintenance Plan and revised motor vehicle emission budgets. The EPA's comments on the budgets were addressed in that email and in the final plan.
§ 93.118(e)(4)(iii)
The motor vehicle emissions budget(s) are clearly identified and precisely quantified.
                                       Y
The motor vehicle emission budgets for 2020 and 2025 are clearly identified in Table 5 of the Indian Wells Second Maintenance Plan. These budgets reflect control measures that are already adopted and implemented. Section IV.E ("Transportation Conformity") and Appendix D ("IWV Precursor Emission Inventories 2002-2005") explain how the budgets were quantified. The information in Table 5 shows that the budgets represent the sum of certain emissions source categories included in the plan inventory, including vehicular exhaust, tire, and brake wear; re-entrained paved road dust; re-entrained unpaved road dust; and road construction dust and include a safety margin. The paved road emissions were estimated using AP-42 with California-specific silt loading factors. The unpaved emissions were estimated using CARB's methodology 7.10, updated in 2012 for non-farm roads. The emissions for the remaining components of the budget were developed using the EPA-approved EMFAC2017 emissions model with VMT and speed distribution data from the 2018 Regional Transportation Plan/2019 Federal Transportation Improvement Program adopted by the Kern Council of Governments (KCOG) and amended as of July 2019.
§ 93.118(e)(4)(iv)
The motor vehicle emissions budget(s), when considered together with all other emission sources, are consistent with applicable requirements for reasonable further progress, attainment, and maintenance (whichever is relevant to a given implementation plan submission).
                                       Y
The EPA has preliminarily concluded that the budgets for the years 2020 and 2025, when considered with all other emission sources, are consistent with the requirement for PM10 maintenance plans to demonstrate maintenance of the 1987 PM10 NAAQS for at least 10 years after redesignation. This finding is based on review and proposed approval of the maintenance demonstration in the Indian Wells Second Maintenance Plan. See section X of the proposed action on the Indian Wells Second Maintenance Plan. 

The Indian Wells Second Maintenance Plan does not include budgets for PM10 precursors, including VOC and NOX, because transportation-related emissions of VOC and NOX are not a significant contributor to the PM10 emissions in the Indian Wells Valley area. See section IV.B and IV.D and Appendix D. We concur with the State's conclusion that motor vehicle emissions budgets are not needed for the PM10 precursors, including VOC and NOX, for the purposes of the maintenance plan for the Indian Wells Valley area. 
§ 93.118(e)(4)(v)
The plan shows a clear relationship among the emissions budget(s), control measures, and the total emissions inventory.
                                       Y
The emissions inventories for all stationary, area, on-road mobile, and non-road mobile sources, and their relation to existing measures, are described in sections IV.B and IV.D of the Plan, and in more detail in Appendix D. The MVEBs shown in Table 5 and documented in sections IV.E through IV.H, are consistent with the on-road emissions estimates in Table 3 and the emissions estimates in Appendix C. 
§ 93.118(e)(4)(vi)
Revisions to previously submitted control strategy or maintenance plans explain and document any changes to any previously submitted budgets and control measures; impacts on point and area source emissions; any changes to established safety margins (see § 93.101 for definition), and reasons for the changes (including the basis for any changes to emission factors or estimates or vehicle miles traveled).
                                       Y
The most recent conformity budgets found adequate by the EPA for the PM10 NAAQS were approved effective June 6, 2003 (68 FR 24368, May 7, 2003) and were established as part of the first maintenance plan for the 1987 PM10 standards. Those budgets were for the years 2001 and 2013 and did not include on-road exhaust emissions, only fugitive emissions. The new budgets in the Indian Wells Second Maintenance Plan include on-road emissions from EMFAC2017. More detailed information on the changes incorporated into EMFAC2017 can be found at https://ww2.arb.ca.gov/our-work/programs/mobile-source-emissions-inventory/msei-road-documentation. EMFAC2017 was approved by the EPA on August 15, 2019 (84 FR 41717), and the EPA's August 2019 notice of availability for EMFAC2017 details the basis for the changes to the emission factors. The previous budgets were also based on a previous version of AP-42 which was updated in 2011.

The budgets in the Indian Wells Second Maintenance Plan were developed for different years (2020 and 2025) and are based on updated transportation activity data from KCOG and CARB's updated on-road motor vehicle emissions model, EMFAC2017 and include a safety margin.
The maintenance demonstration in the Indian Wells Second Maintenance Plan can accommodate the safety margin included in the 2025 budget.
§ 93.118(e)(5)
EPA has reviewed the state's compilation of public comments and responses to comments that are required to be submitted with any implementation plan.
                                      N/A
No comments were received by the District or CARB (see document titled Completeness Checklist for SIP Revision that was included as part of the Indian Wells Second Maintenance Plan submittal package).
 
