Document ID: EPA-R07-OAR-2020-0289-0013
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2020-06-22T04:00Z

Ms. Darcy Bybee
Director, Air Quality Control Program
Air Pollution Control Program
P.O. Box 176
Jefferson City, MO 65102-0176

Dear Ms. Bybee,

The U.S. Environmental Protection Agency appreciates the opportunity to participate in the State's rulemaking process. The EPA is providing comments pursuant to the public notice of the following rules of which the Missouri Department of Natural Resources has indicated its intent to revise and submit to the EPA for inclusion in the State Implementation Plan:

 10 CSR 10-2.205: Control of Emissions from Aerospace Manufacture and Rework Facilities
 10 CSR 10-2.230: Control of Emissions from Industrial Surface Coating Operations
 10 CSR 10-5.220: Control of Petroleum Liquid Storage, Loading and Transfer
 10 CSR 10-5.295: Control of Emissions from Aerospace Manufacture and Rework Facilities
 10 CSR 10-5.330: Control of Emissions from Industrial Surface Coating Operations
 10 CSR 10-6.045: Open Burning Requirements
 10 CSR 10-6.060: Construction Permits Required
 10 CSR 10-6.062: Construction Permits by Rule
 10 CSR 10-6.065: Operating Permits
 10 CSR 10-6.170: Restriction of Particulate Matter to the Ambient Air Beyond the Premises of Origin
 10 CSR 10-6.220: Restriction of Emission of Visible Air Pollutants
 10 CSR 10-6.261: Control of Sulfur Dioxide Emissions 
 10 CSR 10-6.330: Restriction of Emissions from Batch-Type Charcoal Kilns
 10 CSR 10-6.372: Cross-State Air Pollution Rule Annual NOx Trading Allowance Allocations 
 10 CSR 10-6.374: Cross-State Air Pollution Rule Ozone Season NOx Trading Allowance Allocations 
 10 CSR 10-6.376: Cross-State Air Pollution Rule Annual SO2 Trading Allowance Allocations 
 10 CSR 10-6.390: Control of NOx Emissions from Large Stationary Internal Combustion Engines

The EPA has reviewed the available information in the Draft Text document, the Regulatory Impact Report, the Rulemaking Report, and the Response to Comment for each of the rule revisions. As discussed between the EPA and the MoDNR staff, the EPA is providing these detailed comments to help improve clarity and to simplify the proposed rule changes where possible, in line with the State's efforts to streamline rules. 

The EPA is committed to working with the State to help streamline rules and to ensure that when the rule revisions are submitted to the EPA as SIP revision submissions, the submissions contain the information required to meet the Clean Air Act requirements of Section 110(l) and are protective of the National Ambient Air Quality Standards.

                                    Sincerely,
							
                                    Mark A. Smith
                                    Acting Division Director 
                                    Air and Waste Management Division
Enclosure

This enclosure includes comments on the Missouri Department of Natural Resources' proposed rule revisions as provided on the State's Regulatory Action Tracking System webpage and posted for 60-day public comment from August 1, 2018 to October 4, 2018. The EPA's comments are based upon the available information for each rule including the Draft Text document, Regulatory Impact Report, Rulemaking Report and the Response to Comments. These detailed comments are provided to help improve clarity and to simplify the proposed rule changes where possible, in line with the State's efforts to streamline rules. The EPA provided comment on these rule revisions on June 5, 2018, during the Regulatory Impact Report phase of the MoDNR's rulemaking process. The EPA is resubmitting comments that it did not find addressed in the MoDNR's Response to Comment documents. 
Rule Specific Comments:
10 CSR 10-2.205 Control of Emissions from Aerospace Manufacture and Rework Facilities and 10 CSR 10 CSR 10-5.295 Control of Emissions from Aerospace Manufacture and Rework Facilities
 As previously commented, there are two references in this rule to a different rule, 10 CSR 10-6.030(22); however, section (22) does not currently exist in 10 CSR 10-6.030 Sampling Methods. The EPA is aware that the MoDNR proposed to add this section to 10 CSR 10-6.030 during a public comment period from May 15, 2018, to August 02, 2018. As such, the EPA would not act on this submission until 10 CSR 10-6.030 was also submitted to EPA. 
 As previously commented, the EPA encourages the MoDNR to assess the need for adding a reference to 10 CSR 10-6.030(22) in subsection (5)(A) or (5)(C) of this rule because these sections already specify which test method to use (Method 24 and Methods 18, 25, and/or 25A respectively) and where the methods can be found (40 CFR Part 60, Appendix A). The proposed rule text language for the potential revisions to 10 CSR 10-6.030, adding section (22) incorporates 40 CFR Part 60 by reference.  It may be unnecessary to divert the public to another state regulation which incorporates a federal regulation by reference and provides no additional clarity than what is already specified in the subsection (5)(A) and (5)(C) of this rule.
10 CSR 10-2.230 Control of Emissions from Industrial Surface Coating Operations
 As previously commented, where the MoDNR is introducing definitions not previously used (e.g., can coating), the EPA recommends that the MoDNR use already codified definitions found in the Code of Federal Regulations or in the State Implementation Plan where available. 
 While the Response to Comment document indicates that the MoDNR intends to delete the definition "can coating"; the proposed rule text on the Missouri Secretary of State webpage still includes the definition "can coating."
 As previously commented, the MoDNR is adding exemptions to 10 CSR 10-2.230 at subsection (1)(C).  The MoDNR will need to submit a demonstration with the SIP submission showing how the added exemptions meet the requirements of Clean Air Act sections 110(l) and 193 of the also known as the "anti-backsliding" provisions. These sections relate to the EPA's authority to approve a SIP revision that removes or modifies control measure(s) in the SIP only after the state has demonstrated that such a removal or modification will not interfere with attainment of the National Ambient Air Quality Standards, Rate of Progress, Reasonable Further Progress or any other applicable requirement of the CAA.
10 CSR 10-5.220 Control of Petroleum Liquid Storage, Loading and Transfer
 As previously commented, the rule text proposes to change the applicability of this rule in paragraph (3)(C)1. from tanks that are between 500 gallons up to 1,000 gallons to tanks that are 550 gallons up to 1,000 gallons. Because of the change in applicability, the MoDNR will need to ensure that MoDNR's State Implementation Plan submission meets the requirements of sections 110(l) and 193 of the CAA. It should be noted that the MoDNR did rely on this regulation as part of its maintenance plan for the 1997 PM2.5 NAAQS.
 The EPA has previously commented that it recommends that the MoDNR add information to the rule at part (3)(C)1.C.(III) explaining how the staff director will determine equivalency of the pressure/vacuum valve.
      The Response to Comment Document states: "The draft language provides for the staff director to approve a pressure/vacuum valve that is equivalent to that certified by CARB. We feel this equivalent language is adequate for the smaller size tanks covered under this paragraph and is protective of air quality. Adding specific test method requirements such as EPA recommends would not be consistent with how larger tank components are addressed in paragraphs (3)(C)2. and (3)(C)3."
      The EPA recognizes that the rule allows flexibility for approval of components for larger tanks; however, the EPA is still concerned that the rule as drafted does not specify a way for the staff director to determine equivalency to a pressure/vacuum valve that is California Air Resource Board certified. The EPA continues to recommend that the MoDNR add information to part (3)(C)1.C.(III). For example, language could be added indicating that the staff director will determine that a pressure/vacuum valve is equivalent if it has met the alternative test method requirements in 40 CFR § 63.7(f) as specified in 40 CFR § 63.11120(a)(1)(ii). The EPA is concerned about the approvability of this rule in the absence of this additional language.
10 CSR 10-5.330 Control of Emissions from Industrial Surface Coating Operations
      No comment.
10 CSR 10-6.045 Open Burning 
 As previously commented, where the MoDNR is introducing definitions not previously used in its rule (e.g. air curtain incinerator, vegetative waste, wood processing facility), the EPA recommends that the MoDNR use already published definitions found in the CFR or MoDNR's approved 111(d) state plans where applicable.
      For example, MoDNR is proposing to define air curtain incinerator at 10 CSR 10-6.045(2)(A), but has not previously defined this term in its 10 CSR 10-6.045 Open Burning regulation or its 10 CSR 10-6.020 Definitions and Common Reference Tables regulation. The EPA recommends that the MoDNR use a previously promulgated definition such as the definition for air curtain incinerator provided at 40 CFR Part 60, Subpart CCCC- Standards of Performance for Commercial and Industrial Solid Waste Incineration Units (CISWI) (40 CFR § 60.2245), 40 CFR Part 60, Subpart DDDD- Emissions Guidelines and Compliance and Times for CISWI (40 CFR § 60.2810) or the state's 111(d) plan to implement the CISWI guidelines as approved at 40 CFR Part 62, Subpart AA, 40 CFR § 62.6360.
      The definition of air curtain in subsection (2)(A) is different than the definition in subsection (3)(F). Since the definition at subsection (3)(F) aligns with already promulgated definitions at 40 CFR § 60.2245, 40 CFR § 60.2810 and the state's approved CISWI 111(d) plan, the EPA recommends that the MoDNR revise its proposed definition at subsection (2)(A) to match subsection (3)(F).
 As previously commented, the proposed rule text removes a reference to 40 CFR Part 60 Subpart CCCC which identifies that air curtain incinerators are CISWIs. The EPA continues to recommend that the MoDNR retain this reference, and add clarifying language that air curtain incinerators that meet the conditions of this rule are also required to meet the requirements of 40 CFR §§ 60.2242 (Title V permit obligations), 60.2250 (emission limitations obligations), 60.2255 (opacity monitoring obligations), and 60.2260 (record keeping and reporting obligations).
 The following differences in the proposed text at paragraphs (3)(F)1., (3)(F)2., subsection (3)(G), and section (4) should be corrected if mirroring "parts" of 40 CFR §§ 60.2245 through 60.2260 of Subpart CCCC in the Open Burning rule is MoDNR's intent (as described in the Response to Comments document).
 The word "and" is missing between paragraph 3(G)1. and paragraph (3)(G)2. (40 CFR § 60.2250)
 The requirement for opacity to be determined by using the average of three 1-hour blocks is missing from paragraph (3)(G)3. (40 CFR § 60.2250))
 The words "60 days after achieving the maximum production rate at which the affected facility will be operated, but not later than 180 days after initial startup of such facility initial test" as specified in §60.8 is missing from section (5). (40 CFR § 60.2255)
 Subsection (4)(D) requires the submission of the initial and annual opacity test results no later than 60 days following the test but it does not indicate where or to whom the submission should be made.  The EPA encourages the MoDNR to include clear and specific submission requirements.
 As previously commented, the EPA encourages the MoDNR to assess the need for adding a reference to 10 CSR 10-6.030(22) in subsection (5) of this rule because this subsection already specifies which test method to utilize (Method 9) and where it can be found (40 CFR Part 60, Appendix A-4). The proposed rule text language for the potential revisions to 10 CSR 10-6.030, adding section (22), just incorporates 40 CFR Part 60 by reference. It may be unnecessary to divert the public to another state regulation, which then incorporates a federal regulation by reference and provides no additional clarity, when the requirement is already specified section (5) of this rule.

10 CSR 10-6.060 Construction Permits Required
 As previously commented, the EPA recommends that the MoDNR move the information at subsection (1)(C) which establishes the need to obtain a permit to subsection (1)(A) to provide additional clarity to the public. Additionally, the use of "has" at subsection (1)(A) seems like a series of incomplete sentences. For example, (1)(A)(5) states "Has construction of an incinerator." The EPA recommends "Before construction of an incinerator."
 As previously commend, the EPA recommends that the MoDNR clarify the new criteria in paragraph (1)(A)3. The Response to Comments document indicates this is addressed but it is still unclear. Paragraph (1)(A)3 uses the term "emission increase" but does not specify if the "emission increase" is based on actual emissions, allowable emissions, or potential to emit. It also does not specify a time frame (i.e., an annual emission increase can occur without having an hourly emission increase) to evaluate. Additionally, paragraph (1)(A)3. seems to require a permit for any increase, no matter how small an increase, if the existing installation has a potential to emit greater than the de minimis threshold levels.
 Previously, the EPA suggested that the MoDNR use "begin actual" instead of "commence" construction at paragraph (1)(D)1. because "begin actual construction" is defined in 10 CSR 10-6.020 Definitions and Common Reference Tables (which adopts the definitions in paragraph (b) of 40 CFR § 52.21). The revised proposed rule text uses "start of actual construction". "Start of actual construction" is not defined and using this phrase makes the rule unclear to its meaning. The EPA recommends using "begin actual construction" or clearly defining "start of actual construction" in the rule.
 The EPA suggest that the MoDNR revise the language at (1)(A)(4). because new construction would not be a major modification the way it is defined. The EPA suggests the following language: "The modification is a major modification as defined in 40 CFR § 52.21(b) or for nonattainment pollutants as defined in 40 CFR § 51.165(a)(1)(v)."
 As previously commented, the EPA recommends that the MoDNR retain the existing applicability language for portable equipment in 10 CSR 10-6.060(4)(A)1. because the new language appears to allow very large expansions at existing installations. Since the focus of the applicability appears to be based on the size of "construction or modification" (e.g. the project) and not the size of the installation, the 250 ton per year applicability criteria for particulate matter could far exceed the de minimis thresholds if the existing source is already major for particulate matter; potentially triggering Prevention of Significant Deterioration review. Since the air quality analysis in section (4)(E) is discretionary, very large sources of PM could potentially qualify for a portable permit in conflict with the requirement that any new construction or modification not cause or contribute to an air quality exceedance. If MoDNR proceeds with the expanded 250 tpy PM applicability threshold for portable projects, the MoDNR will need to ensure that MoDNR's State Implementation Plan submission meets the requirements of sections 110(l) and 193 of the CAA.
 The Response to Comments document indicates that the MoDNR plans to add the definitions of "screening model action levels" and "risk assessment levels" to the rule (a suggestion previously made by the EPA) and that the MoDNR "plans to work with EPA to ensure SIP approval of the HAP modeling requirements." The EPA would like to clarify that the EPA's approval of the HAP modeling requirements would be completed in accordance with CAA Section 112(l) and is not a SIP action.
 As previously commented, the proposed text of 10 CSR 10-6.030(21) incorporates 40 CFR Part 51 by reference. It is not recommended for the state to incorporate 40 CFR Part 51 in whole. If the federal definitions of 40 CFR Part 51 are absent or differ from those found in 10 CSR 10-6.020 Definitions and Common Reference Tables or 10 CSR 10-6.060(2), for clarity, the EPA recommends that the full text of the definitions (e.g. major stationary source, major modification, net emissions increase and significant), are included at sections (2), (7) or even 10 CSR 10-6.020 rather than incorporate 40 CFR Part 51 in whole, by reference.
 The EPA recommends that the MoDNR review the wording of the definition of "Chemical Process Plant" in paragraph (7)(A)1. to determine if including the word "not" meets with the department's intention of adding the definition to the section. That is, the EPA believes that the MoDNR meant to say that ethanol plants are included in the definition of "Chemical Process Plant" in section (7) of the rule as opposed to the proposed text that says that ethanol plants are not included in the definition. Additionally, for the purpose of implementing section (7) of the rule, the EPA recommends that the MoDNR clarify that the definition of "Chemical Process Plant" found at paragraph (7)(A)(1) supersedes any definition of "Chemical Process Plant" in paragraph (7)(B)6. which refers to the incorporation by reference of 40 CFR 52.21 in subsection (8)(A).
 The revised proposed rule addresses the EPA's previous recommendation that the MoDNR consider revising the proposed language at section (9), however the revised language appears to no longer specify who must obtain a permit. The EPA recommends additional clarification of the proposed rule text to make it clear to the public when a permit is needed at section (9). The EPA would like to clarify that this section would not be approved into the SIP. Instead the requirements of 40 CFR § 63.42(a) would apply for the CAA § 112(g) requirements.
 As previously commented, because "general" permits are more akin to permits-by-rule, and contain administrative requirements that apply directly to the MoDNR, the EPA recommends moving section (6) to its own rule (i.e., promulgating 10 CSR 10-6.063, General Construction Permit for example) so that sources can quickly evaluate any benefit they might gain from the streamlined permitting requirements.
10 CSR 10-6.062 Construction Permits by Rule 
 The EPA recommends that the MoDNR retain the language that it has proposed to delete from subparagraph (3)(B)2.E. that specifies the operational temperature of the second chamber of the incinerator. It would be unclear to the public what temperature is to be monitored, and whether an alarm would be triggered by a temperature excursion, if this language is removed from the rule. 
 The proposed rule allows the use of manufacturer's specification or a stack test to show 99.9% combustion efficiency, however, it is unclear from the rule what minimum temperature is required if a stack test option is used. EPA recommends that MoDNR add a minimum temperature requirement and ensure that the requirement in the rule is clear. For example, is it the average temperature during the test, the lowest temperature during the test, or some other temperature? The MoDNR should also make clear how the combustion efficiency is determined, the test methods used, and what pollutants are measured.
10 CSR 10-6.065 Operating Permits
 The EPA previously recommend that the MoDNR revise items 2. and 3. of the Regulatory Impact Report to clarify which sources specifically would no longer need to obtain a basic operating permit, how the MoDNR will be made aware of the presence of new sources if not requiring a basic operating permit, which "other air program rules" the source would need to follow and how compliance with "other air program rules" will be enforced. The Response to Comment document states that these changes were made; however, the EPA does not see the revised language to items 2. and 3. in the RIR posted on the Missouri Regulatory Action Tracking System webpage.
 As previously commented, the EPA recommends that the MoDNR create separate standalone rules (e.g., promulgating 10 CSR 10-6.066 Intermediate State Permits to Operate and 10 CSR 10-6.067 Title V Operating Permits) to increase clarity to the public on the different permitting programs in the state and the permitting expectations of those programs if the MoDNR finalizes the revisions to 10 CSR 10-6.065 as proposed (i.e., removing the basic operating permit program).
 As previously commented, the EPA recommends that the MoDNR consider switching the requirement, in subsection (5)(D), that a source provide notification to the state if it wants to opt-out of unified review to a requirement that a source provide notification to the state if it wants to opt-in to unified review instead.
10 CSR 10-6.170 Restriction of Particulate Matter to the Ambient Air Beyond the Premises of Origin 
       The EPA previously recommended that the MoDNR add provisions to the rule to make it clear what a "reasonable degree" is, which "techniques" the director might approve, and how the director might make that determination (the proposed language is found at paragraph (3)(A)2. and the addition of section (5) Test Methods which states, "do not apply".)
      The Response to Comment document states that the MoDNR is not making changes to the proposed rule text because the proposed language does not "change the regulatory language already approved in the SIP." The EPA believes it is appropriate to provide comment to the MoDNR on language that would strengthen the proposed language and/or provided clarity to the public. Without provisions in the rule to make it clear what a "reasonable degree" is, which "techniques" the director might approve and how the director might make that determination, the EPA would need to evaluate the approvability of this provision when submitted as a State Implementation Plan revision.
       The EPA recommends that the MoDNR provide regulatory language on what record keeping and reporting requirements would exist for a facility to determine compliance with the rule.
10 CSR 10-6.220 Restriction of Visible Air Contaminants
       The EPA previously commented on the proposed text at subsection (1)(A) which exempts internal combustion engines from the opacity rule. The EPA's concern is these engines, if fired with diesel, can have visible emissions that exceed the numeric opacity limits in section (3) of the proposed rule text. In previous comment, the EPA recommended that the MoDNR consider limiting the exemption to internal combustion engines firing natural gas or other clean gaseous fuels to ensure that MoDNR's State Implementation Plan submission meets the requirements of sections 110(l) and 193 of the CAA.
      The MoDNR's Response to Comment document indicates that it was not making changes to the rule based on the EPA's recommendation because the proposed rule text does not change the regulatory language in a SIP revision submittal made in November 2016. The EPA has not acted on the November 2016 SIP revision submittal. The EPA's obligation in review is to compare the proposed rule text changes to the approved SIP rule text. As such, the EPA continues to recommend that the MoDNR add language to the proposed rule limiting the exemption to internal combustion engines firing natural gas or other clean gaseous fuels.
       As previously commented, the EPA recommends that the MoDNR consider exempting Portland Cement kilns from the rule altogether in section (1) as it has for Industrial, Commercial, and Institutional Boilers and Process Heaters subject to 40 CFR Part 63, subparts DDDDD, JJJJJ and UUUUU, if all the Portland Cement plants in Missouri are subject to 40 CFR Part 63, subparts LLL and EEE.
       The EPA previously recommended that the MoDNR further explain its rationale in the RIR why the visible emission limits in section (3)(A) seem to still apply to portland cement kilns even though the monitoring requirement has been removed.  In some cases, portland cement operations have had difficulty with detached plumes or secondary formation of PM away from the stack which are often not detectable by a COMS or CMS at the stack location, so its possible MoDNR may be retaining the numerical portland cement kiln opacity limits at section (3)(A) for these types of instances. The public can only assume that this is so the state can still act on opacity emissions exceeding the numerical thresholds which are otherwise met at the stack and verified through the continuous monitoring required by 40 CFR Part 63, subparts LLL and EEE. The MoDNR's Response to Comment document states that the MoDNR "plans to further explain that 10 CSR 10-6.220 still applies to Portland cement kilns" but the EPA could not find revised language in the documents posted on the MoDNR's Regulatory Action Tracking System webpage or the Missouri Secretary of State website.
       As previously commented, the EPA recommends that the MoDNR revise the RIR language to reference the correct CFR citation as follows, "strict particulate matter (PM) limits in 40 CFR 60 63 Subparts LLL and EEE." The Response to Comment document states that the MoDNR intends to modify the RIR but the version of the RIR on the MoDNR's Regulatory Action Tracking System webpage does not contain the revisions. 
       As previously commented, the EPA recommends that the MoDNR revise the RIR language to reference the correct term as follows, "required to monitor PM emissions using PM continuous opacity emissions monitoring systems (CEMS) which are more sensitive than COMS." The Response to Comment document states that the MoDNR intends to modify the RIR but the version of the RIR on the MoDNR's Regulatory Action Tracking System webpage does not contain the revisions.
       As previously commented, there are three references to the regulatory citation 10 CSR 10-6.030(22); however, section (22) does not exist in the state's 10 CSR 10-6.030 Sampling Methods. The EPA understands, from review of the MoDNR's Regulatory Action Tracking System webpage, that the MoDNR is in the process of revising 10 CSR 10-6.030 Sampling Methods and that those potential rule changes were made available for public comment from May 15, 2018, to August 02, 2018. As such, the EPA would not act on this submission until 10 CSR 10-6.030 was also submitted to the EPA.
       As previously commented, the EPA encourages the MoDNR to assess the need for adding a reference to 10 CSR 10-6.030(22) in sections (2), (3), and (5) of this rule because those sections already specify which 40 CFR Part 60 requirements apply. The proposed rule text language for the potential revisions to 10 CSR 10-6.030, adding section (22), incorporates 40 CFR Part 60 by reference. It may be unnecessary to divert the public to another state regulation, which then incorporates a federal regulation by reference, and provides no additional clarity, when the requirement is already specified in sections (2), (3), and (5) of this rule.
10 CSR 10-6.261 Control of Sulfur Dioxide Emissions
 Based on the information provided in the Response to Comment document, the RIR and the Rulemaking Report, the EPA is concerned with the proposed rule text removing "Table I  -  Sources with SO2 emission limits necessary to address the 2010 1-hour SO2 National Ambient Air Quality Standard" from section (3)(A) and to remove the requirement for owners or operators of sources subject to the rule in Jackson and Jefferson Counties to accept delivery of only ultra-low sulfur distillate fuel oil with a maximum fuel sulfur content of 15 ppm for use in unit(s) fueled, in whole or in part, by diesel, No. 1 fuel oil and/or No. 2 fuel oil, no later than January 1, 2017 from section (3)(D).
      The Response to Comment letter indicates that the MoDNR intends to submit a redesignation request to the EPA for the Jackson County 1-hour Sulfur Dioxide nonattainment area. To redesignate an area to attainment a NAAQS, the state must demonstrate to the EPA that the area is attaining the standard based on permanent and enforceable conditions. Provisions in Table I were specifically listed in the MoDNR's 2015 Nonattainment Area Plan for the Jackson County 2010 1-hr SO2 nonattainment area as necessary for attainment of the NAAQS.[,]  By removing the limits from the SO2 rule, and not describing why the specific limit is no longer necessary or providing a citation to another document where the emission limit is duplicated (and both permanent and enforceable), the removal of Table I from 10 CSR 10-6.261, and the ultra-low sulfur distillate fuel oil requirement, introduces uncertainty as to how this will ensure protection of the NAAQS. For the EPA to redesignate the area to attainment, the MoDNR would need to provide additional explanation for why the limits originally identified in Table I, and the requirement to burn ultra-low sulfur fuel in applicable units, are no longer necessary.
 As previously commented, item 3 in the RIR discusses the "environmental and economic costs and benefits of the proposed rulemaking." However, there is no discussion on the environmental costs or benefits of the proposal. For example, how does removing the provision in subsection (3)(D) that requires sources in Jackson and Jefferson counties to only use ultra-low sulfur distillate fuel oil to allow sources to use a wider range of fuels impact attainment and maintenance of the NAAQS? Does removing this fuel restriction that part of the 2015 Jackson County 1-hr SO2 Nonattainment Area SIP control strategy impact the environment or negatively affect SIPs that MoDNR has submitted for the EPA's approval? At a minimum MoDNR should explain how the change in the limit of liquid fuel sulfur content in Jackson County from 15 ppm to 35,249 ppm (pre-1968 units) or 8,812 ppm (post-1968 units) would not impact the Jackson County nonattainment area's ability to attain and or maintain the NAAQS.
10 CSR 10-6.330 Restriction of Emissions from Batch-Type Charcoal Kilns 
      No comment.
10 CSR 10-6.372 Cross-State Air Pollution Rule Annual NOx Trading Allowance Allocations 
No comment.
10 CSR 10-6.374 Cross-State Air Pollution Rule Ozone Season NOx Trading Allowance Allocations
 The EPA previously provided comment that the RIR and the Rulemaking Report describing the MoDNR's proposed action to incorporate the Cross State Air Pollution Rule Federal Implementation Plan into the State Implementation Plan by reference included some inconsistencies with the FIP methodology for allocating CSAPR NOX Ozone Season Group 2 allowances. Specifically, the EPA had concern with the Rule Making Report listing three sections (40 CFR § 97.811(a), 40 CFR § 97.811(b)(1), and 40 CFR § 97.812(a)) that should not be included in the list of exclusions and the RIR language does not explain the differences between allocation methodologies in the proposed rule text for ozone season program compliance versus annual program compliance. The Response to Comment document states that the MoDNR "plans to update question number (3) of the Rulemaking Report to remove the references to 40 CFR § 97.811(a), 40 CFR § 97.811(b)(1), and 40 CFR § 97.812(a)" and "provide a description of the difference between the alternative allocation methodologies (alternative approaches) in question 7 of the RIR so that it is clear what they are and which state CSAPR rules they affect." However, this revised language was not available in the documents posted on the MoDNR Regulatory Action Tracking System webpage for review.
10 CSR 10-6.376 Cross-State Air Pollution Rule Annual SO2 Trading Allowance Allocations
	No comment.
10 CSR 10-6.390 Control of NOx Emissions from Large Stationary Internal Combustion Engines
 The EPA previously commented that the MoDNR will need to submit a demonstration showing how the added exemption for Spark Ignition engines to the exemption provided at paragraph (1)(B)2., to the State Implementation Plan submission meets the requirements of Section 110(l) and 193 of the also known as the "anti-backsliding" provisions of the CAA. The Response to Comment document indicates that a demonstration was posted to the MoDNR's Regulatory Action Tracking System webpage. While the EPA would agree that a 25 tpy NOx source is unlikely to have a significant impact on air quality, the demonstration does not discuss air quality near the exempt sources. The EPA recommends that the MoDNR add rationale why this SIP change would not impact attainment of standards near the exempt source to ensure that the SIP meets the anti-backsliding requirements of the CAA section 110(l).
 As previously commented, there are three references to the regulatory citation 10 CSR 10-6.030(22); however, section (22) does not exist in the SIP approved 10 CSR 10-6.030 Sampling Methods. The EPA understands, from review of the MoDNR's Regulatory Action Tracking System webpage, that the MoDNR is in the process of revising 10 CSR 10-6.030 Sampling Methods and that those potential rule changes were made available for public comment from May 15, 2018, to August 02, 2018. As such, the EPA would not act on this submission until 10 CSR 10-6.030 was also submitted to the EPA.
 As previously commented, the EPA encourages the MoDNR to assess the need for adding a reference to 10 CSR 10-6.030(22) to sections (4) and (5) of this rule. These sections already specify that the requirements are for a Continuous Emissions Monitoring Station installed to meet the requirements of 40 CFR 60, Appendix B and F. The proposed rule text language for the potential revisions to 10 CSR 10-6.030, adding section (22), just incorporates 40 CFR Part 60 by reference. It may be unnecessary to divert the public to another state regulation, which then incorporates a federal regulation by reference, and provides no additional clarity, when the requirement is already specified in sections (4) and (5).