Approval and Promulgation of Air Quality Implementation Plans; Montana; Billings/Laurel Sulfur Dioxide State Implementation Plan
Federal RegisterMay 2, 2002
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Environmental Protection Agency
40 CFR Part 52
[MT-001-0007, MT-001-0008, MT-001-0009 and MT-001-0010; FRL-7175-1]
Approval and Promulgation of Air Quality Implementation Plans; Montana; Billings/Laurel Sulfur Dioxide State Implementation Plan
AGENCY:
Environmental Protection Agency (EPA).
ACTION:
Final rule.
SUMMARY:
EPA is partially approving and partially disapproving the Billings/Laurel sulfur dioxide (SO2) State Implementation Plan (SIP) revisions submitted by the State of Montana in response to a SIP Call. EPA is also limitedly approving and limitedly disapproving one provision of the SIP revisions. The SIP revisions establish, and require seven sources to meet and monitor compliance with, SO2 emission limitations and other requirements in the Billings/Laurel area. The intended effect of this action is to make federally enforceable those provisions that EPA is approving and to disapprove those provisions that do not meet applicable requirements. EPA is taking this action under sections 110 and 179 of the Clean Air Act (Act). In a separate action being published today, EPA is proposing action on other provisions of the Billings/Laurel SO2 SIP.
EFFECTIVE DATE:
This final rule is effective June 3, 2002.
ADDRESSES:
Copies of the documents relevant to this action are available for public inspection during normal business hours at the Air and Radiation Program, Environmental Protection Agency, Region 8, 999 18th Street, Suite 300, Denver, Colorado, 80202 and copies of the Incorporation by Reference material at the Air and Radiation Docket and Information Center, Environmental Protection Agency, 401 M Street, SW, Washington, DC 20460. Copies of the State documents relevant to this action are available for public inspection at the Montana Department of Environmental Quality, Air and Waste Management Bureau, 1520 E. 6th Avenue, Helena, Montana 59620.
FOR FURTHER INFORMATION CONTACT:
Laurie Ostrand, EPA, Region 8, (303) 312-6437.
SUPPLEMENTARY INFORMATION:
Table of Contents
Definitions
I. Summary of EPA's Final Action
II. EPA's Action on the State of Montana's Submittals
A. Why Is EPA Approving Parts of the State of Montana's Plan?
B. Why Is EPA Disapproving Parts of the State of Montana's Plan?
C. Why Is EPA Proposing Action on Parts of the State of Montana's Plan?
D. What Happens When EPA Approves Parts of the State of Montana's Plan?
E. What Happens When EPA Disapproves Parts of the State of Montana's Plan?
F. What Happens When EPA Limitedly Approves and Limitedly Disapproves Parts of the State of Montana's Plan?
III. Other Issues Pertaining to State Authority
A. How Do the State-Only Provisions Affect EPA's Actions?
B. How Does Montana's Environmental Audit Act Affect EPA's Actions?
IV. Other Rulemaking Actions
A. How Does This Final Action Relate to EPA's SIP Call?
B. Why Is EPA Not Imposing Sanctions?
V. What Comments Were Received on EPA's Proposed Action and How Is EPA Responding to Those Comments?
VI. Administrative Requirements
Definitions
For the purpose of this document, we are giving meaning to certain words or initials as follows:
(i) The words or initials
Act
or
CAA
mean or refer to the Clean Air Act, unless the context indicates otherwise.
(ii) The initials
CEMS
mean or refer to continuous emission monitoring systems.
(iii) The words
EPA, we, us
or
our
mean or refer to the United States Environmental Protection Agency.
(iv) The initials
FIP
mean or refer to Federal Implementation Plan.
(v) The initials
MBER
mean or refer to the Montana Board of Environmental Review.
(vi) The initials
MDEQ
mean or refer to the Montana Department of Environmental Quality.
(vii) The initials
MSCC
mean or refer to the Montana Sulphur & Chemical Company.
(viii) The initials
NAAQS
mean or refer to the national ambient air quality standards.
(ix) The initials
SIP
mean or refer to the State Implementation Plan.
(x) The initials
SO2
mean or refer to sulfur dioxide.
(xi) The words
State
or
Montana
mean the State of Montana, unless the context indicates otherwise.
(xii) The initials
TSD
mean or refer to the Technical Support Document.
(xiii) The initials
YELP
mean or refer to the Yellowstone Energy Limited Partnership.
I. Summary of EPA's Final Action
Apart from those provisions we are disapproving, limitedly approving/limitedly disapproving, proposing to act on in a separate action published today (
see
discussion below), or not acting on, we are approving all other aspects of the Billings/Laurel SO2 SIP, which the State of Montana submitted in response to our SIP Call.
See
Background section V.D. in our proposed rulemaking action published on July 28, 1999 (64 FR 40791) for a discussion of the SIP Call. Our approval is based on several interpretations of provisions of the SIP. The interpretations described in our proposed approval still apply except that, based on comments received, we have revised the interpretation of “low sulfur fuel gas.”
See
section V.Q. below. We caution that if we find it too difficult to enforce certain variable (or pro-rated) emission limitations at several of the sources or if data are not available to determine the emission limitations on a regular basis, we will reconsider our approval. Also, if we determine that the State-only provisions, as implemented, appear to limit or constrain or otherwise have a chilling effect on the Montana Department of Environmental Quality's (MDEQ's) enforcement of the SIP, we will reconsider our approval or take other appropriate action under the Act. Our reconsideration could occur under section 110(k)(6) of the Act or we could complete another SIP Call under sections 110(a)(2)(H) and 110(k)(5) of the Act. We caution that if sources are subject to more stringent requirements under other provisions of the Act (
e.g.,
section 111 new source performance standards; Title I, part C prevention of significant deterioration; or SIP-approved permit programs under Title I, part A), our approval of the SIP (including emission limitations and other requirements), would not excuse sources from meeting these other, more stringent requirements. Also, our action on this SIP is not meant to imply any sort of applicability determination under other provisions of the Act (
e.g.,
section 111; Title I, part C; or SIP-approved permit programs under Title I, part A).
We are disapproving the following provisions of the Billings/Laurel SO2 SIP
1
:
1
The SIP was submitted in the form of orders, stipulations, exhibits and attachments for each source covered by the plan. The majority of the requirements are contained in the exhibits. Throughout this document when we refer to an exhibit, we mean exhibit A to the stipulation for the specified source.
• The escape clause (paragraph 22 in the ExxonMobil
2
and MSCC stipulations and paragraph 20 in the
Cenex, Conoco, Montana Power, Western Sugar and YELP stipulations).
2
Between our July 28, 1999 proposal action and this action, Exxon's name was changed to ExxonMobil. Our July 1999 proposal simply referred to Exxon.
• The MSCC stack height credit and emission limitations on the sulfur recovery unit (SRU) 100-meter stack (paragraph 1 of the ExxonMobil stipulation, paragraphs 1 and 2 of the MSCC stipulation, and section 3(A)(1)(a) and (b) and 3(A)(3) of the MSCC exhibit).
• The emission limitation on MSCC's auxiliary vent stacks, section 3(A)(4) of MSCC's exhibit.
• The attainment demonstration, because of improper stack height credit and emission limitations at MSCC.
• The attainment demonstration for lack of flare emission limitations at Cenex, Conoco, ExxonMobil, and MSCC.
• The attainment demonstration, because of the disapproval of the emission limitation for MSCC's auxiliary vent stacks.
• The Reasonably Available Control Measures (RACM) (including Reasonably Available Control Technology (RACT)) and Reasonable Further Progress (RFP) requirements for Cenex.
• The provisions that allow sour water stripper emissions to be burned in the flare at Cenex and ExxonMobil (the following phrase from section 3(B)(2) of Cenex's exhibit A and section 3(E)(4) of ExxonMobil's exhibit A: “or in the flare”; the following phrases in section 4(D) of Cenex's exhibit A and section 4(E) of ExxonMobil's exhibit A: “or in the flare” and “or the flare”. )
We are limitedly disapproving the following provision:
• The emission limitation for the 30-meter stack at MSCC (section 3(A)(2) of MSCC's exhibit A) because it lacks a reliable compliance monitoring method.
We are not acting on the following provisions:
• The provisions in section 6(B)(3) of MSCC's exhibit that require certain monitoring equipment to support the variable emission limitations.
In a separate action published today, we are proposing action on the following provisions of the Billings/Laurel SO2 SIP submitted on July 29, 1998
3
:
3
In our July 28, 1999 proposed action we proposed to conditionally approve these provisions based on the Governor's commitment to address concerns we had raised. The Governor submitted a SIP revision on May 4, 2000 which was intended to fulfill the commitments. Since the Governor has submitted a SIP revision to fulfill the commitments, we are not finalizing our proposed conditional approval and instead are proposing separate action on parts of the July 29, 1998 submittal (
i.e.,
those parts we proposed to conditionally approve on July 28, 1999) and all of the May 4, 2000 submission (which is some cases modified the provisions of the July 29, 1998 submittal).
• YELP's emission limitations (in section 3(A)(1) through (3) of YELP's exhibit).
• ExxonMobil's coker CO-boiler emission limitation (in section 3(B)(1) of ExxonMobil's exhibit).
• ExxonMobil's F-2 crude/vacuum heater stack emission limitations and attendant compliance monitoring methods (specifically, section 3(A)(2) of exhibit A; section 3(B)(3) of exhibit A; the following phrase from section 3(E)(4) of exhibit A “except that the sour water stripper overheads may be burned in the F-1 Crude Furnace (and exhausted through the F-2 Crude/Vacuum Heater stack) or in the flare during periods when the FCC CO Boiler is unable to burn the sour water stripper overheads, provided that: (a) such periods do not exceed 55 days per calendar year and 65 days for any two consecutive calendar years, and (b) during such periods the sour water stripper system is operating in a two tower configuration.”; section 4(E) of exhibit A; and method #6A of attachment #2,
4
of exhibit A).
4
In our July 28, 1999 proposal action, we proposed to conditionally approve all of attachment #2 of ExxonMobil's exhibit. We should have limited our proposed conditional approal to only method #6A of attachment #2 of ExxonMobil's exhibit.
• ExxonMobil's fuel gas combustion emission limitations and attendant compliance monitoring methods (in sections 3(A)(1), 3(B)(2), 4(B), and 6(B)(3) of ExxonMobil's exhibit).
• Cenex's combustion sources emission limitations and attendant compliance monitoring methods (specifically, section 3(A)(1)(d) of exhibit A; the following phrase from section 3(B)(2) of exhibit A “except that those sour water stripper overheads may be burned in the main crude heater (and exhausted through the main crude heater stack) or in the flare during periods when the FCC CO boiler is unable to burn the sour water stripper overheads from the “old” SWS, provided that such periods do not exceed 55 days per calendar year and 65 days for any two consecutive calendar years.”; section 4(B) of exhibit A; section 4(D) of exhibit A; and method #6A of attachment #2
5
of exhibit A).
5
In our July 28, 1999 proposal action, we proposed to conditionally approve all of attachment #2 of Cenex's exhibit. We should have limited our proposed conditional approval to only method #6A of attachment #2 of Cenex's exhibit.
We have also revised the regulatory text from what was proposed. The regulatory text appears at the end of this notice. The proposed regulatory text started at 64 FR 40807 (July 28, 1999). As indicated later in this notice, we are not selecting the order of sanctions as we had proposed. Therefore, we are
not
including the regulatory text that was proposed for 40 CFR 52.32(b). Also, we proposed to conditionally approve several provisions of the SIP. Since we are not finalizing the conditional approval of those provisions, and instead are proposing action on them in a separate notice being published today, the regulatory text at the end of this notice also excludes from the incorporation by reference the provisions we proposed to conditionally approve.
See
40 CFR 52.1370(c)(46)(i)(A), (C) and (G). We also expanded 40 CFR 52.1370(c)(46)(i)(A) and (C) to explicitly indicate the phrases not being incorporated by reference at this time. Additionally, based on comments received, we are not acting on an additional provision of MSCC's exhibit and excluding it from the incorporation by reference.
See
40 CFR 52.1370(c)(46)(i)(E). Finally, we added regulatory text at the end of this notice to indicate those provisions of the stipulations and/or exhibits that we are partially or limitedly disapproving.
See
40 CFR 52.1384(d).
II. EPA's Action on the State of Montana's Submittals
A. Why Is EPA Approving Parts of the State of Montana's Plan?
On July 28, 1999 (64 FR 40791) we proposed to partially approve the Billings/Laurel SO2 SIP. Our proposed rulemaking action discussed several issues that we resolved with the State as well as interpretations we made of several provisions in the Billings/Laurel SO2 SIP. We have considered the comments received
6
and still believe we should partially approve the plan as proposed except that we are limitedly approving/disapproving one provision of the SIP, the emission limitation for the 30-meter stack at MSCC, that we had proposed to partially approve.
6
The comments received and our response to the comments are discussed below in section V., entitled “What Comments Were Received on EPA's Proposed Action and How Is EPA Responding to Those Comments?”
Additionally, EPA believes partially and limitedly approving the Billings/Laurel SO2 SIP meets the requirements of section 110(l) of the Act. The approved provisions of the plan strengthen the Montana SIP by providing specific control strategies and compliance determining methods for SO2 sources in Billings/Laurel, Montana which further the goals of and achieve progress toward attaining the SO2 NAAQS.
B. Why Is EPA Disapproving Parts of the State of Montana's Plan?
In our July 28, 1999 proposed rulemaking, we proposed to partially disapprove portions of the Billings/Laurel SO2 SIP. We have considered the comments received and still believe we should partially disapprove the SIP as proposed. In addition, because of comments received we are not acting on an additional provision of the SIP.
See
the discussion in section II.B.2 below. Finally, because of comments received, we are limitedly disapproving one provision of the SIP.
See
the discussion in section II.B.6 below. The parts of the Plan we are disapproving follow:
1. Escape Clause
Each stipulation contains a paragraph which allows a source to withdraw its consent to the stipulation. The “escape clause” is printed in full in our July 28, 1999 proposed rulemaking action (
see
right column of 64 FR 40797).
We are disapproving the escape clause because, if sources invoke the escape clause, the MDEQ will no longer have a plan to implement. Specifically, we are disapproving the following: paragraph 22 in the ExxonMobil and MSCC stipulations; paragraph 20 in the Cenex, Conoco, Montana Power, Western Sugar and YELP stipulations. If sources invoke the escape clause after our final action on the SIP, we expect to respond by issuing another SIP Call under sections 110(a)(2)(H) and 110(k)(5) of the Act or taking other appropriate action under the Act. Additionally, with the disapproval of the escape clause, the provisions of the SIP that we approve will remain federally enforceable even if one or more of the sources invoke the escape clause. While our disapproval of the escape clause eliminates the risk of a source's future attempt to nullify the SIP, we do not believe our disapproval renders the SIP more stringent than the State of Montana intends, because our disapproval does not change the stringency of any of the substantive requirements the State of Montana has imposed and is currently able to enforce under the SIP. Moreover, a source's exercise of the escape clause would not represent the State's decision to suspend its own SIP or constitute any decision on the part of the State to change the SIP's enforceable requirements. Finally, since the escape clause is a provision that EPA could not lawfully approve under title I of the CAA, the only alternative to EPA's partial disapproval would be a total disapproval of the SIP, which we believe the State would not favor over today's action.
2. MSCC Stack Height Credit and Emission Limitations on the Sulfur Recovery Unit (SRU) 100-Meter Stack
We are disapproving MSCC's SRU 100-meter stack height credit and emission limitations (paragraph 2 of the MSCC stipulation and sections 3(A)(1)(a) and (b) and 3(A)(3) of the MSCC exhibit) used in the attainment demonstration modeling for the Billings/Laurel area. We believe it is necessary to disapprove MSCC's emission limitations because the State of Montana has set limitations based on an amount of stack height credit for MSCC that is not supportable under section 123 of the Act or our stack height regulations.
Our July 28, 1999 proposed rulemaking action (starting in the left column of 64 FR 40798), and TSD to that proposal, discuss the Act's stack height requirements (
see
those documents for the complete discussion).
Additionally, because of comments received we are not acting on the monitoring provisions in section 6(B)(3) of MSCC's exhibit. Since we are disapproving MSCC's variable emission limitation, we believe it does not make sense to approve section 6(B)(3) of MSCC's exhibit, which requires MSCC to install certain monitoring equipment to support the use of the variable limitation. Section 6(B)(3) would be needed only if we were approving MSCC's variable emissions limitation.
3. Language in ExxonMobil and MSCC's Stipulations Related to Incorporation of Earlier Stipulations and Apportionment of the Airshed
Paragraph 1 of the ExxonMobil and MSCC stipulations discusses a contested case hearing and resultant February 2, 1996 stipulation and incorporates the February 2, 1996 stipulation by reference. We do not believe it is appropriate to incorporate the February 2, 1996 stipulation into the SIP because it discusses procedures and schedules for developing emission limitations for ExxonMobil and MSCC that have subsequently been developed and that, for MSCC, are not approvable (
see
discussion on stack height issue at MSCC in section II.B.2, above). Paragraph 1 of the ExxonMobil and MSCC stipulations also contains a statement that the company enters into the stipulation “in part, to preserve [the company's] rights to apportionment of the airshed resulting from the present SIP revision.” Insofar as this statement implies that the companies or other air pollution sources are entitled to a property interest in the ambient air in the Billings/Laurel area or enjoy a right to pollute the ambient air, this statement conflicts with the purpose and requirements of the Act and has no basis under federal law. By this statement we do not mean that we do not recognize emission rights created by statute (
e.g.
, Titles I and IV of the Act). However, the phrase “right of apportionment of the airshed” implies possessory rights to the ambient air. We are concerned that the phrase might imply rights less conditional than those created by the Act. Therefore, we are disapproving paragraph 1 of the ExxonMobil and MSCC stipulations.
4. MSCC Auxiliary Vent Stacks
We are disapproving the MSCC auxiliary vent stacks emission limitation (section 3(A)(4) of MSCC's exhibit). We believe it is necessary to disapprove this emission limitation because the exhibit does not restrict the sulfur content of the fuel burned in the boilers and heaters, when they are exhausting from auxiliary vent stacks, and lacks a monitoring method that would make the emission limitation practically enforceable. Without a restriction on the fuel burned and a compliance monitoring method, there is the potential that exceedances of the emission limitation would go undetected.
5. Attainment Demonstration
7
7
One commenter stated that we did not acknowledge that Montana submitted two separate attainment demonstrations for SO2—one for the Billings area and one for the Laurel area. The commenter indicated that the Laurel area was modeled assuming the SIP prescribed emission limitations for Cenex and the pre-SIP potential emissions for the Billings sources. Therefore, the Laurel SIP demonstrates compliance with the NAAQS regardless of whether a revised SIP is approved and implemented in Billings. The Billings area was modeled assuming all sources in Laurel and Billings area are at SIP prescribed emission rates. Therefore, the Billings SIP depends upon approval of the Laurel SIP to demonstrate attainment. The commenter is requesting that we acknowledge the two attainment demonstrations in our final action and treat the two separately in that action. We agree with the commenter and acknowledge that there are two attainment demonstrations—one for the Billings area and one for the Laurel area. However, since the flare issue applies to sources in Billings and in Laurel, we still believe the attainment demonstration for both areas should be disapproved for lack of enforceable flare emissions at the applicable sources.
For us to fully approve a SIP, the SIP must show that the NAAQS will not be violated,
i.e.,
that the area demonstrates attainment. Attainment demonstrations are usually carried out with computer models that are approved by us. The computer models take numerous factors into consideration to predict the effects that emissions from various sources will
have on levels of pollutants in the air. Models consider the typical meteorology and topography of the area, as well as physical parameters at a plant site,
e.g.,
the height, temperature, and velocity at which pollutants are emitted. Based on these factors, as well as restrictions placed on sources to control their emissions, models are used to predict the highest pollution levels that can be expected to occur in the future. For the reasons discussed below, we are disapproving the attainment demonstrations for the Billings/Laurel SIP.
a. Improper Stack Height Credit and Emission Limitation at MSCC
The MDEQ used EPA-approved dispersion models to demonstrate attainment of the SO2 NAAQS in the Billings/Laurel area. However, the modeling for the July 29, 1998 submittal of the SIP relied on emission limitations at MSCC that were established with a stack height credit that exceeded the good engineering practice (GEP) stack height. As discussed above in section II.B.2, we are disapproving the emission limitations and stack height credit for the 100-meter stack at MSCC. We are also disapproving the attainment demonstration because it relies on these improper emission limitations and stack height credit.
b. Lack of Flare Emission Limitations
With the July 29, 1998 submittal of the SIP, the State of Montana removed all reference to flare emission limitations from the exhibits submitted for Federal approval. In June 1998, the MBER adopted “Additional State Requirements” (hereinafter referred to as “State-only provisions”) for each of the seven sources in the Billings/Laurel area. The State-only provisions include flare emission limitations and reporting requirements for the four sources that have flares (Cenex, Conoco, ExxonMobil, and MSCC). Because the State-only provisions were not submitted for inclusion in the Billings/Laurel SO2 SIP, they may be enforced only by the MDEQ.
Since flare emissions were considered part of the attainment demonstration and since there appear to be routine emissions from flares, we believe the SIP should contain enforceable emission limitations for these emission points. Therefore, we are disapproving the SIP as it applies to the attainment demonstration for lack of enforceable emission limitations for flares.
See
our July 28, 1999 proposed rulemaking action, middle column, 64 FR 40801, for more information on this issue.
c. Disapproval of MSCC Auxiliary Vent Stacks Emission Limitation
As indicated above, we are disapproving the emission limitation on the auxiliary vent stacks in MSCC's exhibit because the exhibit does not restrict the sulfur content of the fuel burned in the boilers and heaters, when they are exhausting from auxiliary vent stacks, and lacks a monitoring method that would make the emission limitation practically enforceable. The attainment demonstration relies on the auxiliary vent stacks emission limitation at MSCC. Since we are disapproving the emission limitation, we believe it is also necessary to disapprove the attainment demonstration.
6. MSCC 30-Meter Stack
We are limitedly disapproving/limitedly approving the MSCC 30-meter stack emission limitation (section 3(A)(2) of MSCC's exhibit). We believe it is necessary to limitedly disapprove this emission limitation because the exhibit does not adequately limit the fuel burned in the boilers and heaters that are exhausting from the 30-meter stack, and does not provide a monitoring method that would make the emission limitation practically enforceable.
8
8
In some cases, a SIP rule may contain certain provisions that meet the applicable requirements of the Act, but that are inseparable from other provisions that do not meet all the requirements. Although the submittal may not meet all of the applicable requirements, we may consider whether the rule, as a whole, has a strengthening effect on the SIP. If this is the case, limited approval may be used to approve a rule that strengthens the existing SIP as representing an improvement over what is currently in the SIP and as meeting some of the applicable requirements of the Act. At the same time we would disapprove the rule of the SIP for not meeting all of the applicable requirements of the Act. Under a limited approval/disapproval action, we approve and disapprove the entire rule even though parts of it do and parts do not satisfy requirements under the Act. The rule remains a part of the SIP, even though it has been limitedly disapproved, because the rule strengthens the SIP. The disapproval only concerns the failure of the rule to meet a specific requirement of the Act and does not affect incorporation of the rule as part of the approved, federally enforceable SIP.
7. Burning of Sour Water Stripper (SWS) Emissions in the Flare at Cenex and ExxonMobil
With the July 29, 1998 submittal of the SIP, Cenex's and ExxonMobil's exhibits now allow SWS emissions to be burned in the flare. As discussed above, flare emission limitations were deleted from the July 1998 submittal. Therefore, SWS emissions, if burned in the flare, are unregulated. We believe that unless flares have an enforceable emission limitation, it is unacceptable to allow SWS emissions to be burned in the flare. Because we believe that allowing SWS emissions to be burned in the unregulated flare is not an acceptable approach, we are disapproving those provisions of the Cenex and ExxonMobil stipulations that would allow such approach (the following phrase from section 3(B)(2) of Cenex's exhibit A and section 3(E)(4) of ExxonMobil's exhibit A: “or in the flare”; the following phrases in section 4(D) of Cenex's exhibit A and section 4(E) of ExxonMobil's exhibit A: “or in the flare” and “or the flare”.)
8. Reasonably Available Control Measures (RACM) Including Reasonably Available Control Technology (RACT) and Reasonable Further Progress (RFP) at Cenex
As indicated earlier, we are disapproving the attainment demonstration for the SIP. Because we are disapproving the attainment demonstration, we conclude that the RACM (including RACT) and RFP requirements have not been met in the Laurel SO2 nonattainment area.
9
See
discussion in sections III.C.(15) and (16) of our TSD for further information.
9
RACM (including RACT) and RFP requirements only apply in areas designated as nonattainment.
C. Why Is EPA Proposing Action on Parts of the State of Montana's Plan?
In our July 28, 1999 proposed rulemaking action, we proposed to conditionally approve several provisions of the Billings/Laurel SO2 SIP based on a commitment from the Governor of Montana to adopt specific enforceable measures by a specified date.
See
the July 28, 1999 action, 64 FR 40802—40803, for a complete discussion of those parts of the plan we proposed to conditionally approve. On May 4, 2000, the Governor of Montana submitted a SIP revision to fulfill his commitment. Since the Governor has fulfilled his commitment, we believe it is not necessary to finalize the conditional approval. Instead, a separate proposed rulemaking on parts of the July 29, 1998 submittal (
i.e.,
those parts we proposed to conditionally approve on July 28, 1999) and all of the May 4, 2000 submittal (which in some cases modified the July 29, 1998 submittal) is also being published today.
The specific provisions of the July 29, 1998 submittal on which we are proposing a separate action today include:
(1) YELP's emission limitations (section 3(A)(1) through (3) of YELP's exhibit);
(2) ExxonMobil's coker CO-boiler emission limitation (section 3(B)(1) of ExxonMobil's exhibit);
(3) ExxonMobil's F-2 crude/vacuum heater stack emission limitations and attendant compliance monitoring methods (section 3(A)(2) of exhibit A; section 3(B)(3) of exhibit A; the following phrase from section 3(E)(4) of exhibit A “except that the sour water stripper overheads may be burned in the F-1 Crude Furnace (and exhausted through the F-2 Crude/Vacuum Heater stack) or in the flare during periods when the FCC CO Boiler is unable to burn the sour water stripper overheads, provided that: (a) such periods do not exceed 55 days per calendar year and 65 days for any two consecutive calendar years, and (b) during such periods the sour water stripper system is operating in a two tower configuration.”; section 4(E) of exhibit A; and method #6A of attachment #2, of exhibit A);
(4) ExxonMobil's fuel gas combustion emission limitations and attendant compliance monitoring method (sections 3(A)(1), 3(B)(2), 4(B), and 6(B)(3) of ExxonMobil's exhibit); and
(5) Cenex's combustion sources emission limitations and attendant compliance monitoring methods (section 3(A)(1)(d) of exhibit A; the following phrase from section 3(B)(2) of exhibit A “except that those sour water stripper overheads may be burned in the main crude heater (and exhausted through the main crude heater stack) or in the flare during periods when the FCC CO boiler is unable to burn the sour water stripper overheads from the “old” SWS, provided that such periods do not exceed 55 days per calendar year and 65 days for any two consecutive calendar years.”; section 4(B) of exhibit A; section 4(D) of exhibit A; and method #6A of attachment #2 of exhibit A.)
Because we are proposing separate action on the above provisions, at this time we are not incorporating these provisions into the Federally approved SIP.
See
the regulatory text that follows at the end of this document.
D. What Happens When EPA Approves Parts of the State of Montana's Plan?
Once we approve a SIP, or parts of a SIP, the portions approved are legally enforceable by us and citizens under the Act.
E. What Happens When EPA Disapproves Parts of the State of Montana's Plan?
Once we disapprove a SIP, or parts of a SIP, the disapproved portions are still enforceable at the State level but not at the Federal level. By disapproving parts of the plan, we are determining that the requirements necessary to demonstrate attainment in the area have not been met and we may develop a plan or parts of a plan to assure that attainment will be achieved. Also, in some cases, once we disapprove a plan, sanctions may be imposed. As noted below, at this time, sanctions will not be imposed in the Billings/Laurel area as a result of this partial and limited disapproval.
F. What Happens When EPA Limitedly Approves and Limitedly Disapproves Parts of the State of Montana's Plan?
Once we limitedly approve/disapprove a SIP, or parts of a SIP, those provisions are legally enforceable by us and citizens under the Act. Under a limited approval/disapproval action, we approve and disapprove the entire rule even though parts of it do and parts do not satisfy requirements under the Act. The rule remains a part of the SIP, however, even though there is a disapproval, because the rule strengthens the SIP. The disapproval only concerns the failure of the rule to meet specific requirements of the Act and does not affect incorporation of the rule as part of the approved, federally enforceable SIP. To the extent the rule fails to satisfy requirements of the Act, we intend to develop a plan or parts of a plan to meet such requirements.
III. Other Issues Pertaining to State Authority
A. How Do the State-Only Provisions Affect EPA's Actions?
In our July 28, 1999 proposed rulemaking action we indicated that in June 1998, the MBER adopted “Additional State Requirements” for each of the seven sources in the Billings/Laurel area. These requirements (hereinafter referred to as the “State-only provisions”) were not submitted for inclusion in the SIP and are enforceable only by the State of Montana.
See
64 FR 40803, bottom right column of our July 28, 1999 action for a complete discussion of the State-only provisions.
We have considered the comments received on our discussion of State-only provisions in our proposal and still believe it is appropriate to conclude that since the State-only provisions were not included in the Billings/Laurel SO2 SIP, we are not approving or disapproving these provisions nor are we relying on these provisions in approving or disapproving other provisions in the submitted SIP. Nothing in this action should be construed as making any determination or expressing any position regarding the State-only provisions or their impact on the SIP. State-only provisions can affect only State enforcement of the SIP and cannot have any impact on federal enforcement authorities. We may at any time invoke our authority under the Act, including, for example, sections 113, 114, or 167, to enforce the requirements of the Billings/Laurel SO2 SIP independent of any State enforcement effort. We may take action to enforce the SIP regardless of any State compliance determination or any constraint on State enforcement discretion which the State-only provisions may impose. In addition, citizen enforcement under section 304 of the Act is likewise unaffected by the State-only provisions.
If we were to determine that the State-only provisions, as implemented, appeared to limit, constrain, or otherwise have a chilling effect on state enforcement of the SIP, we would reconsider our approval or take other appropriate action under the Act. Our reconsideration could occur under section 110(k)(6) of the Act or we could complete another SIP Call under sections 110(a)(2)(H) and 110(k)(5) of the Act. Other appropriate action could include a finding of failure to implement the SIP under section 179(a)(4) of the Act or enforcement action under section 113(a)(2) of the Act, or both.
B. How Does Montana's Environmental Audit Act Affect EPA's Actions?
On May 5, 1997, the Governor of Montana signed a bill enacted by the legislature (the Voluntary Environmental Audit Act, Mont. Code Ann. §§ 75-1-101
et seq.
(1999), (H.B. 293, effective October 1, 1997)) that creates immunity under State law from penalties for violations discovered during a voluntary environmental audit and creates a judicial privilege under State law for information contained in an environmental audit report.
In our July 28, 1999 action we indicated that nothing in our proposal action should be construed as making any determination or expressing any position regarding the State of Montana's audit privilege and penalty immunity law or its impact upon any provisions in the SIP, including the proposed revision at issue.
However, our concerns about the effect of the audit law on the State's ability to enforce the SIP have been addressed by a formal agreement with the State. On December 13, 1999, EPA and the State entered into a Memorandum of Agreement (“MOA”) (
see
document # IV.C-32) concerning the effects of the audit law on state implementation and enforcement of all federal environmental programs in
Montana. Under the MOA, as long as the agreement and the State's legal interpretations of the audit law are in effect and functioning as intended, we and the State agree that State environmental programs, including the SIP, have sufficient authority to obtain and maintain EPA approval.
The State of Montana's audit privilege and immunity law affects only state enforcement and does not have any impact on federal enforcement authorities. We may at any time invoke our authority under the Act, including for example, sections 113, 114, or 167, to enforce the requirement or prohibitions of the State of Montana's plan, independent of any state enforcement effort. In addition, citizen enforcement under section 304 of the Act is likewise unaffected by a state audit privilege or immunity law.
IV. Other Rulemaking Actions
A. How Does This Final Action Relate to EPA's SIP Call?
In our July 28, 1999 proposal we indicated that our March 4, 1993 letter requesting revision of the Billings/Laurel area SO2 SIP (
see
document # II.G-1) stated that the letter was not final Agency action subject to judicial review, and that a final Agency action would occur when we made a binding determination regarding the State's response. We have considered the comments received on our proposed rulemaking action and still believe it is appropriate to finalize action on the SIP Call and on the State of Montana's response to the March 4, 1993 letter; we are making a binding determination regarding the SIP Call and the State of Montana's response to the letter with this final rulemaking action.
B. Why Is EPA Not Imposing Sanctions?
In our July 28, 1999 proposed rulemaking action, starting at 64 FR 40804, right column, we proposed that the sanctions specified in section 179(b) of the Act should apply if our proposed disapproval action became a final disapproval action. We also requested comment on whether we should accelerate the sanctions under section 110(m) of the Act. After reviewing the comments
10
received on our proposal action, we have decided not to select the order of sanctions that would apply in the Billings/Laurel area at this time. Consequently, if the 18-month sanctions clock that starts with today's disapproval of Montana's SIP expires without the State having corrected the identified deficiencies, no sanctions will be imposed. In the future, if we choose to select the order of mandatory sanctions or to apply early discretionary sanctions, we would do so through rulemaking.
10
See
footnote 7 above.
V. What Comments Were Received on EPA's Proposed Action and How Is EPA Responding to Those Comments?
Summary of Comments and Responses
Following is a summary of the comments received on the proposed rulemaking and our responses. The following is an outline of the subjects on which we received comments:
A. SIP Call
B. Sanctions
C. Flares
D. Dispersion Modeling
E. EPA's Partial Approval
F. Due Process for SIP Approval
G. Escape Clause
H. Language in ExxonMobil and MSCC Stipulations Related to Incorporation of Earlier Stipulations and Apportionment of the Airshed
I. Default Approval of SIP
J. Department Discretion
K. Quarterly Data Recovery Rate (QDRR)
L. Effect of the Montana Voluntary Environmental Audit Act
M. Effect of State-only Provisions
N. Enforcement and MDEQ Staffing
O. Reasonably Available Control Measures (RACM) Including Reasonably Available Control Technology (RACT) and Reasonable Further Progress (RFP) at Cenex
P. MSCC Auxiliary Vent Stacks
Q. MSCC's 30-meter Stack
R. ExxonMobil's and Cenex's Refinery Fuel Gas Limitation
S. Variable Emission Limitations
T. Minor Sources
U. Compliance Determining Method—ExxonMobil's Coker CO-Boiler Stack and F-2 Crude/Vacuum Heater Stack
V. Effect of the 1990 Amendments to the Clean Air Act
W. Stack Height Issues
A. SIP Call
We issued a request for revision of the Billings/Laurel area SO2 SIP by letter to the Governor of Montana, dated March 4, 1993 (
see
document # II.G-1). The request letter reflected our preliminary finding regarding the SIP's substantial inadequacy (SIP Call), and was published in the
Federal Register
on August 4, 1993 (58 FR 41430) (
see
document # II.G-3). In the request letter, we declared that the SIP Call would become final agency action when we made a binding determination regarding the State of Montana's response to the SIP Call. We proposed to make such binding determination regarding the SIP Call when we proposed to partially approve, conditionally approve, and partially disapprove the Billings/Laurel SO2 SIP revisions submitted by the State on Montana in response to the request letter.
See
64 FR 40791, 40804 (July 28, 1999) (
see
document # III.A-2).
Summary of Comments and Response
Two commenters objected that the SIP Call is invalid and should be withdrawn.
We have considered the comments received and still believe our March 4, 1993 letter was appropriate and that we should make the SIP Call for the Billings/Laurel area a final agency action.
The following is a summary of the comments received and our response to the comments:
(1)
Comment:
Two commenters (MSCC letter, document # IV.A-19, comment #'s 1, 125; Goetz letter, document # IV.A-18, exhibit D, comment # III, p. 43) stated that the SIP Call is invalid and that subsequent actions by the State in response to the 1993 letter and by EPA on the State's SIP revision are invalid as well. These commenters submitted extensive comments on the dispersion modeling that was the basis of the 1993 letter, claiming that the modeling was defective and was not supported by monitoring data.
Response:
We will address the comments on dispersion modeling and monitoring in section V.D. of this document, together with similar comments concerning the State's modeled demonstration of the effectiveness of the new SIP emission limitations. Please
see
section V.D., below (“Dispersion Modeling”). Here we will address other comments on the validity of the SIP Call.
(2)
Comment:
One commenter (MSCC letter, document # IV.A-19, comment # 1; MSCC letter, document # IV.A-20, comment #'s 3.A, 3.B), stated that the SIP Call violates due process because it undoes an earlier approval of the existing SIP, while the letter was not made by rulemaking, was not properly noticed, and did not provide for timely and effective challenge because it was not denoted a final agency action. The commenter further stated that irreversible changes occurred without opportunity to challenge the underlying premises of the 1993 letter. Another commenter (Goetz letter, document # IV.A-18, exhibit D, comment # III, p. 43) stated that because the 1993 letter was not binding, presumably because it was not issued by rulemaking, no one could challenge its validity.
Response:
The SIP Call does not violate due process. The provisions of the Act that authorize us to call for SIP revisions do not require rulemaking
until the Agency proceeds to make the SIP Call binding and final. Sections 110(a)(2)(H) and 110(k)(5) of the Act require (1) that we notify the State when we find that the applicable implementation plan is substantially inadequate to protect the NAAQS, and (2) that we make the notice public. When we sent our letter to the Governor of Montana on March 4, 1993 and published the letter in the
Federal Register
, see 58 FR 41430 (August 4, 1993) (document # III.G-3), we in effect provided our preliminary views regarding the SIP's substantial inadequacy and provided the State an early opportunity to respond to our assessment. Thus, we did not make a final, binding finding, and thus were not required to use notice and comment rulemaking procedures to issue the letter. Rather, the final binding action regarding the SIP Call, as well as our action on the State's response to the 1993 letter, is occurring in today's rulemaking. The SIP Call does not “undo” our prior approval of the 1977 SIP for the area or turn that approval into a disapproval. Any SIP Call denotes that the existing SIP has become inadequate, whether due to changes in conditions such as increased emissions, a change in requirements, or, as in this case, a change in our ability to measure the effectiveness of the SIP control strategy to protect air quality.
The opportunity to participate in the SIP development process that began with our letter to the Governor was provided by the public participation requirements of the Montana SIP and the proposed rulemaking in this action.
See
64 FR 40791, 40806 (July 28, 1999) (document # III.A-2). The opportunity to review and comment on the proposed rule, which the commenters have exercised, satisfies the requirements of procedural due process mandated for SIP approval actions by sections 110(a) and 110(k) of the Act and section 553 of the Administrative Procedure Act. Under those provisions, the requirements of due process are satisfied by publication of a notice of proposed rulemaking with an opportunity for submission of written comments prior to final action. The Act does not require formal adjudication or formal rulemaking.
See Cleveland Electric Illuminating Co.
v.
E.P.A.,
572 F.2d 1150, 1157 (6th Cir. 1978);
Buckeye Power, Inc.
v.
EPA,
481 F.2d 162, 172 (6th Cir. 1973).
The appropriate mechanism for obtaining a formal hearing on our rulemaking on the SIP Call and on the SIP is to file a petition for review of this final action in the United States Court of Appeals for the Ninth Circuit, as provided by section 307(b) of the Act. The procedural requirements for exercising the opportunity for judicial review of our final action are discussed elsewhere in this document.
(3)
Comment:
One commenter (MSCC letter, document # IV.A-19, comment #'s 1, 2nd page, 3, 4, 66 and other comments) stated that our SIP Call is an entirely discretionary act that was inadequately justified.
Response:
The statutory provision authorizing SIP Calls provides that “[w]henever the Administrator finds that the applicable implementation plan for any area is substantially inadequate to attain or maintain the relevant national ambient air quality standard.* * * the Administrator
shall
require the State to revise the plan as necessary to correct such inadequacies.” Section 110(k)(5) of the Act (emphasis added). While it is true that EPA has some discretion in finding whether a SIP is substantially inadequate, the use of the imperative “shall,” rather than the optional “may,” appears to require EPA action as mandatory and not discretionary, once we make a finding of substantial inadequacy.
The same commenter believes the SIP Call is not adequately justified and that the Administrator should withdraw the 1993 letter. We believe our technical support document for the SIP Call (document # II.G-2) adequately justifies our final binding decision to call for a SIP revision and that no withdrawal of the1993 letter is necessary.
(4)
Comment:
One commenter (MSCC letter, document # IV.A-19, comment # 1, 2nd page) stated that our SIP Call intrudes on the primary responsibility of the State to implement the Clean Air Act, contrary to section 101 of the Act. Another commenter (Goetz letter, document # IV.A-18, exhibit D, comment # V, p. 61) raised the same objection to our proposed action on the SIP.
Response:
Section 101 of the Act, “Congressional findings and declaration of purpose,” is not a prescriptive provision and does not require particular action by anyone. But it does provide a statement of Congressional intent, which the remaining provisions of the Act effectuate. For example, section 101(a)(3) states a congressional finding that air pollution prevention and control are the “primary responsibility of States and local governments”; section 101(a)(4) states a finding that “[f]ederal financial assistance and leadership is essential for the development of cooperative Federal, State, regional, and local programs to prevent and control air pollution.”
These and other provisions of section 101 of the Act declare an intent to create a cooperative relationship between the federal government and the States “to protect and enhance the quality of the Nation's air resources, so as to promote the public health and welfare” as expressed by section 101(b). As the courts have recognized, “The CAA simply 'establishes a program of cooperative federalism that allows the States, within limits established by federal minimum standards, to enact and administer their own regulatory programs, structured to meet their own particular needs.’ ”
Commonwealth of Virginia
v.
Browner
(80 F.3d 869, 883 (1996) (quoting
Hodel
v.
Virginia Surface Mining & Reclamation Ass'n,
452 U.S. 264, 289, 101 S.Ct. 2352, 2367-68 (1981)).
The intent to create a cooperative relationship for air pollution control is effected by the other provisions of the Act, including section 109, which authorizes us to establish NAAQS; by section 110(a), which directs States to assume the primary responsibility of developing SIPs to protect the NAAQS; and by section 110(k)(5), which authorizes us to take a leadership role by calling for revision when SIPs are found inadequate. Montana's action here, developing and submitting a SIP revision in response to our 1993 letter, fulfills the congressional intent that States take primary responsibility for air pollution control. In the federal partnership, both functions are necessary: both the primary responsibility assumed by the States and our standard-setting and oversight role.
(5)
Comment:
Two commenters (MSCC letter, document # IV.A-19, comment # 2; Goetz letter, document # IV.A-18, exhibit D, comment, p. 9) stated that we improperly constrained the State's action in responding to the 1993 letter, by placing time limits on the State's response and threatening to impose sanctions and withhold federal funds if the State did not submit timely SIP revisions. One of the commenters (MSCC letter, document # IV.A-20, comment # 4F) also stated that until we have promulgated a formal SIP Call for Montana, and given Montana the statutory time following final promulgation of the formal SIP Call, we are not required and may not be authorized to promulgate a FIP. Another commenter (McGarity letter, document # IV.B-1) stated that the process has taken too long.
Response:
The maximum allowable time limits for submission of revisions in response to a SIP Call are established by statute. Section 110(k)(5) of the Act
provides that we “
may
establish reasonable deadlines (not to exceed 18 months after the date of such notice) for the submission of such plan revisions.” (Emphasis added.) However, the statute does not require us to establish a deadline in all cases. In our letter of March 4, 1993, we requested that Montana submit its revisions within an 18-month timeframe, which is consistent with the maximum allowable time where we are making a SIP Call binding and final. Under the letter, the SIP revisions were due on September 4, 1994 if the State chose to comply with the request. The State submitted the revisions on September 6, 1995, nearly a year later than this date. These revisions were modified and resubmitted on August 27, 1996, April 2, 1997 and July 29, 1998. In light of these facts, it is not necessary to establish a further schedule and deadline for the State to respond to the SIP Call in today's rulemaking, since we already have received the State's response.
We did not impose sanctions on Montana for failure to submit the revisions on time, but we did indicate that sanctions would apply in a letter to the State dated September 19, 1994 (document # IV.C-31). This letter and subsequent letters to the State on the timing of sanctions, dated March 14, 1996 (document #'s II.B-16 and B-17), were premature, and we later corrected them. Our authority to impose sanctions under section 179 of the Act can only be implemented after we conduct rulemaking to select the order of the sanctions to be imposed for failure to meet requirements of the Act.
See
section 179(a) of the Act. Because we did not promulgate a general rule for applying sanctions for failure to meet a SIP Call, we can impose them only through specific rulemaking that achieves two things: first, making the SIP Call binding and final so that the State's response becomes a “required” submission under the Act; and second, selecting the order of mandatory sanctions that will apply if the State fails to respond or if EPA disapproves the State's response. In our proposed rulemaking action we proposed to take the prerequisite rulemaking actions and to apply sanctions in the event that our partial disapproval of the SIP revisions became final action.
See
64 FR 40791, 40804 (July 28, 1999) (document # III.A-2). (Our final action on the proposal to impose sanctions is discussed in section V.B., below.)
With respect to whether we can promulgate a FIP without completing formal rulemaking on the SIP Call, by this action, we are promulgating a formal SIP Call and can now propose a FIP to fill any gaps created by our disapproval of the Billings/Laurel SO2 SIP. We do not agree with the commenter that the Act requires us to give the State additional time to respond to the SIP Call and SIP disapproval, before we propose a FIP. Section 110(c) of the Act requires that we promulgate a FIP “at any time within 2 years after” we disapprove a SIP revision in whole or in part. There is no minimum time period before we may promulgate a FIP, but rather a two-year maximum time within which we
must
promulgate a FIP. Because the State has already had nearly nine years in which to respond to the initial 1993 letter, we do not believe that allowing additional time will serve the public interest in protecting the NAAQS through federally enforceable limitations on SO2 emissions.
(6)
Comment:
Two commenters (MSCC letter, document # IV.A-19, comment # 2; Goetz letter, document # IV.A-18, exhibit D, comment # 2, p. 9) also stated that the untimely threat to impose sanctions exerted improper and extreme pressure on Montana and the sources in the area to respond to the 1993 letter. One commenter (MSCC letter, document # IV.A-19, comment # 1, 3rd page) stated that the threat of sanctions was coercive and had the effect of forcing the State to impose emission limitations that were unauthorized and unconstitutional.
Response:
These comments will be addressed in section V.E., below, discussing the Tenth Amendment and other constitutional and statutory challenges to our SIP action.
(7)
Comment:
One commenter (MSCC letter, document # IV.A-19, comment # 1, 1st page) stated that the 1993 letter was invalid because the letter incorrectly stated that the existing SIP for the area did not contain enforceable emission limitations.
Response:
Contrary to the commenter's statement, the 1993 letter does not contain a statement that the pre-1993 SIP did not include enforceable emission limitations. When we issued the 1993 letter, we were aware that some enforceable limitations on SO2 emissions were in place. We took those limitations into account in our analysis. For example, the modeling demonstration that formed the basis of the 1993 letter showed violations of the NAAQS for SO2 at emission levels allowed under existing emission limitations. The 1993 letter did state our view that the SIP in effect at that time was inadequate to attain and maintain the SO2 NAAQS and that emission reductions would likely be necessary to protect the NAAQS.
(8)
Comment:
One commenter (MSCC letter, document # IV.A-20, comment #'s 3J, 3K, 3N, 3Q, 3R) stated that the SIP Call is not binding, adequate or legally effective to say the SIP was inadequate because allowable and actual emissions have been reduced and voluntary improvements have occurred since 1993. Additionally, the commenter stated that since the 1993 letter additional information and facts have become available to further dispute or moot the results of the 1993 modeling and any opinion based thereon.
Response:
The 1993 letter was supported by the evidence available at the time it was issued. That evidence could not have taken into account future events such as more restrictive emission limitations in state permits. Such later actions are irrelevant to the validity of the 1993 letter, though possibly relevant to Montana's response to the letter. Voluntary reductions in emissions since the 1993 letter are also irrelevant; they do not affect the validity of the 1993 letter or our rulemaking on the SIP Call and the SIP revisions.
(9)
Comment:
Two commenters (MSCC letter, document # IV.A-20, comment #'s 3.H., 3.L; Goetz letter, document # IV.A-18, exhibit D, comment # III.B, pp. 44-45) stated that the SIP Call is not binding, adequate or legally effective to say the SIP was inadequate because ambient monitoring in the Billings/Laurel area, both before and after the 1993 letter, did not show any violations of the SO2 NAAQS.
Response:
For a discussion of whether contrary monitoring data invalidate the computer modeling used for the SIP Call and SIP development, readers are referred to the response to comments on modeling in section V.D., below. With respect to measurements of current concentrations, the emissions inventory for the Billings/Laurel area indicates that actual SO2 emissions have declined since 1993. One commenter (MSCC letter, document # IV.A-20, comment # 3.Q) notes that CEMS at the sources show lower emission rates now than at the time of the modeling. Ambient concentrations of SO2 measured by the area's monitoring network, not surprisingly, show a similar decline. To the extent that these reductions reflect the State's efforts to restrict emissions as part of its control strategy, they demonstrate the effectiveness of Montana's response to the SIP Call.
B. Sanctions
We proposed that the regulatory scheme issued for sanctions generally, under 40 CFR section 52.31, should also
apply here if our proposed partial disapproval of the SIP became a final action or if our adopted final conditional approvals later converted to disapprovals. We proposed to apply the sanction rule's provisions regarding the timing of sanctions. We also asked for comment on whether we should impose sanctions under section 110(m) of the Act to make the sanctions effective immediately upon the effective date of partial disapproval or conversion from conditional approval to disapproval, and on the geographic scope of any such discretionary sanctions.
Summary of Comments and Response
Eight commenters submitted comments on our sanctions proposal. Five of the eight commenters were opposed to our imposing sanctions, one commenter seemed only opposed to sanctions in Billings, and two commenters felt we should go beyond what was proposed and apply sanctions throughout the State. Some commenters were also opposed to applying sanctions immediately.
We have considered the comments received, and in our final rule, at this time, we have decided not to select the order of sanctions that would be necessary to apply mandatory sanctions (section 179(b)), or to impose discretionary sanctions (section 110(m)) in the Billings/Laurel area or anywhere else in the State of Montana. Thus, sanctions are not automatic in the Billings/Laurel area as a result of our partial and limited disapproval of the SIP, even if the State does not correct the identified deficiencies within the 18-month period starting with today's disapproval. To apply mandatory sanctions under section 179, we must complete a rulemaking action to specify the order of sanctions. Because the sanctions are not automatic before such action is completed, we believe we can use some of the principles of discretionary sanctions in deciding whether or not sanctions should be applied in the Billings/Laurel area.
We are not required to apply discretionary sanctions under section 110(m) of the Act. Section 110(m) says “[t]he Administrator
may
apply any of the sanctions listed in section 179(b) at any time (or at any time after) the Administrator makes a finding, disapproval or determination under paragraphs (1) through (4), respectively, of section 179(a) in relation to any plan or plan item...required under the Act...” Further, in the preamble of our rulemaking action for discretionary sanctions we indicated that we will exercise section 110(m) sanctions earlier than 18 months only in cases where: (1) the State has indicated an explicit resistance to resolving a plan or program deficiency or to making a required plan or program submittal; or (2) special circumstances, particular program needs, or time constraints dictate the need for use of such sanctions.
See
59 FR 1481 (middle column), January 11, 1994.
In this particular case, the State initially submitted a SIP in September 1995 and then spent several years revising and updating the SIP to, among other things, address our concerns with previous SIP submittals. In a letter dated September 27, 1999 from Mark Simonich, Montana Department of Environmental Quality (MDEQ), to William Yellowtail, EPA, the MDEQ expressed a desire to correct the SIP so that it is approvable. (
See
document # IV.A-31.)
This history shows that the State has not shown resistance to resolving its plan deficiency or to making the required plan submittal. In addition, sources were required to meet the emission limitations in the Billings/Laurel SO2 SIP when the State's Board Order was signed (June 12, 1998), except where another effective date is specified in the exhibit A or attachment(s). Therefore, on the whole, the plan is being implemented now.
Because of the State's efforts to submit an approvable SIP and because the SIP is being implemented, we believe that it is not appropriate to apply discretionary sanctions in the Billings/Laurel area, or anywhere else in the State of Montana, at this time. In the future, if we choose to apply discretionary sanctions or to select the order of mandatory sanctions that would apply, we would do so through rulemaking.
The following is a summary of the comments received and our response to the comments:
(1)
Comment:
Several commenters stated that sanctions are not appropriate in any form, because there have been substantial reductions in SO2 emissions and ambient concentrations in the area; the area meets the NAAQS; and the State and industry have made a good faith effort to submit a SIP to us. (
See
State letter, document # IV.A-23, comment #'s 1A, 1B, 1C, 1D, 1E; Cenex letter, document # IV.A-26, Montana Petroleum Association letter, document # IV.A-17; ExxonMobil letter, document # IV.A-28, State letter, document # IV.A-31, MSCC letter, document # IV.A-20, comment # 4B, 6A; MSCC letter, document # IV.A-19, comment #'s 112, 114.)
Response:
We agree that the State of Montana has made a good faith effort to submit an approvable SIP and that is why we have decided not to apply sanctions at this time. However, we do not agree that substantial reductions in SO2 emissions and ambient concentrations alone should warrant not applying the sanctions. Although sources over the past several years have reduced their actual SO2 emissions, and there has been a corresponding reduction in monitored ambient concentrations, the SIP allows sources to emit more SO2 than they actually do. Also, we have long held that SO2 monitoring may not be a true indication of ambient concentrations because of the nature of SO2 plumes.
See
our September 16, 1982 memorandum from Sheldon Meyers, Director, Office of Air Quality Planning and Standards to David Kee, Director, Air and Management Division, Region V, entitled “Milwaukee SO2 Nonattainment Designation,” and April 21, 1983 memorandum from Sheldon Meyers, Director, Office of Air Quality Planning and Standards to Regional Air Division Directors, entitled “Section 107 Designation Policy Summary” (document #'s IV.C-26 and IV.C-27, respectively). In both memoranda, we indicate that in most SO2 cases, a small number of monitors is usually not representative of the air quality for the entire area. See also response to comments D.2.a. and b.
(2)
Comment:
One commenter stated that imposing sanctions on Montana is unfair because the State made a good faith effort to develop the plan; the plan contains all the necessary elements and shows attainment; the plan may be unnecessary and later overturned by a court or even a subsequent Administrator; and EPA's criticism of the lack of approved emission limitations at this point source arises solely from EPA's failure to approve a reasonable plan and demonstration, and not the State's failure to submit it. The commenter also stated that Montana is not being treated equally with other areas that are attaining the NAAQS. (
See
MSCC letter, document # IV.A-20, comment #'s 4B, 4D, 4E, 6; MSCC letter, document # IV.A-19, comment # 112.)
Response:
As indicated above, we agree that the State of Montana has made a good faith effort to submit an approvable SIP and that is why we have decided not to apply sanctions at this time. We do not agree that the plan submitted by the State contains all the necessary elements and shows attainment.
See
our proposed rulemaking action and TSD, document #'s III.A-2 and III.B-1, respectively, for a complete explanation of why we do not believe the submitted plan contains all the necessary elements. We do not
agree that we should not impose sanctions because of speculation about future challenges to our action or subsequent EPA Administrators. Finally, we do not agree that Montana is not being treated equally with other areas that are attaining the NAAQS.
(3)
Comment:
Several commenters stated acceleration of sanctions is not appropriate. (
See
Conoco letter, document # IV.A-24; Cenex letter, document # IV.A-26.) One commenter stated it is not appropriate to accelerate sanctions for failure to submit a SIP that we could approve in response to a SIP Call the commenter believes was not binding. (
See
MSCC letter, document # IV.A-19, comment # 111.)
Response:
We agree that it is not appropriate to accelerate sanctions, at this time. The ability to accelerate sanctions comes under our discretionary sanction authority in section 110(m) of the Act. As indicated above, in the preamble of our rulemaking action for discretionary sanctions we indicated that we will exercise section 110(m) sanctions earlier than 18 months only in cases where: (1) the State has indicated an explicit resistance to resolving a plan or program deficiency or to making a required plan or program submittal; or (2) special circumstances, particular program needs, or time constraints dictate the need for use of such sanctions.
See
59 FR 1481 (middle column) January 11, 1994. We believe the State has not shown an explicit resistance to resolving a plan deficiency or making a required plan submittal. At this time we do not believe there are special circumstances which warrant accelerating sanctions.
We do not agree with the commenter who stated that we should not accelerate sanctions because the plan is approvable and the 1993 letter was not binding. The issue of whether the 1993 letter was binding is discussed in section V.A., above. Our proposed rulemaking action and TSD provides a full explanation of why we believe the SIP is not fully approvable.
See
document #'s III.A-2 and III.B-1, respectively.
(4)
Comment:
Several commenters stated that sanctions are not appropriate since we were involved when the SIP was developed. The commenters stated our involvement blurred the State's primary role in developing the SIP and our role in approving the SIP. (
See
State letter, document #IV.A-23, comment #'s 1B, 1C, 1E; Cenex letter document # IV.A-26)
Response:
We do not agree that we should not impose sanctions since we were involved when the SIP was being developed. We generally review and comment on SIPs as they are being developed and during the public comment period. Often states will ask for our interpretation of the Act, regulations and guidance so that SIPs, once submitted, will be approvable. In its comments on the proposal, the State of Montana portrayed our involvement in the SIP development as “extensive and at times, overreaching.” We do not agree with this characterization of our involvement and review. However, since we are not applying sanctions, at this time, we do not believe it worthwhile to debate the appropriateness of our involvement with respect to whether that should have any bearing on whether to apply sanctions.
(5)
Comment:
Several commenters stated that imposing sanctions sends the wrong message to the State and sources for their efforts and is inconsistent with the intent of Congress, which is clean air, not punishment. (
See
State letter, document # IV.A-23, comment # 1E.)
Response:
We do agree that, in this case, sanctions may send the wrong message to the State for its SIP efforts and therefore we are not applying the sanctions. We do not agree, however, that applying sanctions would be inconsistent with Congressional intent. By authorizing sanctions for certain kinds of state planning failures, Congress intended to assure that SIPs and SIP revisions would be developed on time, would provide adequate controls, and would otherwise satisfy Act planning requirements.
(6)
Comment:
Several commenters stated that imposing sanctions in this case is a discretionary act by EPA and due to the circumstances in this case the sanctions should not be imposed. (
See
State letter, document # IV.A-23, comment # 1E; Cenex letter, document # IV.A-26; MSCC letter, document # IV.A-20, comment # 4A; MSCC letter, document # IV.A-19, comment # 112.) One commenter stated we are creating a rule structure just so that we could impose sanctions in Montana. (
See
MSCC letter, document # IV.A-20, comment # 4A.) One commenter questions whether we can impose discretionary sanctions under section 110(m) of the Act in cases such as this where section 179 is not applicable. (
See
State letter, document # IV.A-23, comment # 1E.)
Response:
We agree that applying sanctions is a discretionary act in this case and due to the circumstances the sanctions should not be applied at this time. We also agree with the commenter that in our proposal we were creating a rule structure to impose sanctions. Because sanctions are not automatic in this particular case we believed we had to create a rule to impose them.
With respect to the commenter who questioned whether we could apply section 110(m) in cases where EPA is not exercising its authority under section 179, we already addressed this issue when we finalized our criteria for exercising discretionary sanctions under the title I of the Act (59 FR 1476, January 11, 1994). In the January 11, 1994 action, 59 FR 1479-1480, we indicated that “EPA believes that section 110(m) and section 179, although interrelated, do set up two distinct sanctions processes.” Additionally, on page 1480 of the January 11, 1994 action, third column we indicated that “EPA disagrees that section 179 provides the sole authority for imposing sanctions. * * * In fact, the EPA believes the reference to statewide sanctions under section 110(m) makes it clear that section 110(m) establishes a different authority to sanction states.* * *”
While our sanctions authority under both provisions is triggered by a state failure regarding a required submission under the Act, we believe we have independent authority under section 110(m) to impose sanctions, even if we have not completed a separate rulemaking under section 179 to select the sequence of mandatory sanctions. We are choosing not to impose discretionary sanctions at this time. If we decide to impose sanctions in the future under section 110(m) we would propose them through notice and comment rulemaking and the public could comment at that time.
(7)
Comment:
One commenter stated that sanctions are not appropriate because the 1993 letter was not binding, adequate and/or legally effective as a determination that the SIP was inadequate. The same commenter stated we need to go through a rulemaking process on the SIP Call before we can start a sanction clock. The commenter stated that until we go through a rulemaking process we have circumvented the public notice, comment and appeals process that should precede any sanctions. (
See
MSCC letter, document # IV.A-20, comment #'s 3A, 3B, 4B, 4C, 4D, 5E.)
Response:
In this case, we do not agree that sanctions would be inappropriate merely because the 1993 letter was not binding. Today's final action itself makes the SIP Call binding, and partially and limitedly disapproves the State's response to the SIP Call. Section 179(a) of the Act provides the statutory authority to apply sanctions for disapprovals of a SIP, in whole or in part, that is required to be submitted
under a SIP Call (section 110(k)(5)). Today's rulemaking renders the SIP Call binding and final, and takes final disapproval action on the State's required response. Therefore, under the statute, EPA would have the authority to select the order of sanctions that would be necessary to apply mandatory sanctions (section 179(b)), or impose discretionary sanctions (section 110(m)), if we conducted the prerequisite rulemaking and if the State failed to correct the identified deficiencies within 18 months of such rulemaking.
(8)
Comment:
Several commenters stated the geographic scope of the highway sanctions should be the entire state and the offset sanctions the Billings/Laurel area. (
See
YVCC letter, document # IV.A-30.) One commenter stated the geographic scope of the sanctions should be just the Laurel area. (
See
Conoco letter, document # IV.A-25).
Response:
As indicated above, at this time, we are deciding not to apply sanctions anywhere in the State of Montana. Two commenters felt we should apply 2-to-1 emission offset sanctions in the Billings area. For the most part, 2-to-1 emissions offset sanctions can only be applied in areas designated as nonattainment. If we had elected to apply sanctions, since Billings is not a designated nonattainment area, we could not apply 2-to-1 emission offset sanctions there.
See
our January 11, 1994 final rulemaking action on discretionary sanctions, 59 FR 1479-1480, for a more detailed discussion on the geographic scope of sanctions.
(9)
Comment:
Several commenters stated sanctions would disproportionately affect Laurel and Cenex. (
See
Cenex letter, document # IV.A-26; MSCC letter, document # IV.A-20, comment # 5; MSCC letter, document # IV.A-19, comment # 114.) One commenter stated it is unfair to apply sanctions in Laurel because Laurel is a nonattainment area only in name; ambient data show the area is attaining the standard; Laurel is being punished for issues that are occurring in Billings and to which Laurel does not contribute. (
See
MSCC letter, document # IV.A-20, comment #'s 5A, 5C; MSCC letter, documment # IV.A-19, comment # 114.) This same commenter stated that once an area is designated nonattainment it is impossible to be redesignated to attainment. (
See
MSCC letter, document # IV.A-20, comment # 5B.) Finally, this commenter stated that Laurel's nonattainment designation occurred many years ago and was not the result of the issues identified in the current SIP. (
See
MSCC letter, document # IV.A-20, document 5D; MSCC letter, document # IV.A-19, comment # 114.) This commenter further stated that the CAA 1990 requirement that designations be reaffirmed is unreasonable in this case. (
See
MSCC letter, document # IV.A-19, comment #65.) This commenter stated that the area is more controlled now than at the time of Laurel's nonattainment designation and that it is hard to believe that not approving the SIP will jeopardize the NAAQS. (
See
MSCC letter, document # IV.A-20, comment # 5G.)
Response:
As indicated above, at this time, we are deciding not to apply sanctions in Montana. If we had decided to apply sanctions just in the nonattainment area impacted by the Billings/Laurel SO2 SIP, then the commenters are correct that Laurel and Cenex would have been impacted more by the sanctions then the rest of the area and sources. We do not agree with the commenter who stated that applying sanctions in Laurel would be punishing Laurel for a Billings issue. Our proposed disapproval of the SIP, because of the lack of flare provisions, also pertains to Laurel; flare issues pertain in Laurel and Billings.
One commenter questions whether Laurel should be designated as a nonattainment area (presumably because the designation of Laurel impacts the sanctions that could apply). The fact is that Laurel is a designated nonattainment area. We cannot redesignate the area until the State submits a redesignation request and maintenance plan which we can approve. Contrary to the commenter's suggestion, redesignations of SO2 areas from nonattainment to attainment have occurred across the country.
See, for example,
66 FR 14087 (March 9, 2001) and 65 FR 35577 (June 5, 2000). Prior to the Clean Air Act Amendments of 1990 (1990 CAAA), Laurel had an approved Part D plan but was still designated as nonattainment because the State had not submitted a redesignation request. Because Laurel was designated as nonattainment prior to enactment of the 1990 CAAA, upon enactment of the 1990 CAAA, Laurel remained a nonattainment area by operation of law.
See
section 107(d)(1)(C)(i) of the Act. Although one of the commenters states these requirements are unreasonable, we are required to implement the law. Since the 1990 CAAA, we determined that the SIP for the Billings/Laurel area was not adequate to protect the NAAQS. We do not believe we could approve a redesignation request and maintenance plan for Laurel until we determine that the SIP for Laurel is adequate to protect the NAAQS,
i.e.,
until we approve the SIP submitted in response to the SIP Call.
One commenter wonders how non-approval of the SIP will jeopardize attainment since the area is more controlled now than when Laurel was initially designated as nonattainment. What the commenter seems to be asserting is that there is no need for a SIP. We disagree. We found the SIP inadequate under the Act, and, thus, it is incumbent on the State to submit an adequate SIP. Whether emissions in the area have gone down since we issued our 1993 letter or since the State adopted the stipulations for the SIP is irrelevant. Our concern under the Act must be whether the federally approved and enforceable SIP meets the requirements of the Act. Congress gave EPA the ultimate approval role for SIPs.
(10)
Comment:
One commenter stated that damage done by sanctions can not be undone. Because of offset sanctions, sources may avoid projects, shut down or spend more money than is necessary (leaving sources at a competitive disadvantage). Withholding highway funds could cause a safety problem for people. Also, once a highway budget is lost it is irretrievable. (
See
MSCC letter, document # IV.A-20, comment # 5F; MSCC letter, document # IV.A-19, comment # 113.)
Response:
It is difficult to respond to comments which speculate about what might happen in the future. At this point, we are deciding not to apply sanctions. However, as indicated above, Congress intended sanctions to be used to assure that SIPs and SIP revisions would be developed on time, would provide adequate controls, and would otherwise satisfy Act planning requirements. Applying sanctions may have adverse effects. However, highway funds used for safety and environmental projects cannot be withheld for sanctions applied under section 179 or 110(m) of the Act.
(11)
Comment:
One commenter stated that sanctions should not be imposed because of a dispute between the State and Federal governments regarding an interpretation of a regulation. The commenter stated sanctions should not be imposed until the differences are resolved or adjudicated. (
See
MSCC letter, document # IV.A-20, comment #'s 4D, 4E; MSCC letter, document # IV.A-19, comment # 114.)
Response:
We do not agree that sanctions should not be applied merely because of a dispute between the State and EPA regarding an interpretation of a regulation. In this particular case, we told the State in 1996 that we could not
approve the plan based on its interpretation of the stack height regulations. In 1998, the State submitted revisions to the plan knowing that the plan would be disapproved in part.
C. Flares
We proposed to disapprove the SIP as it applies to the attainment demonstration because of the lack of enforceable emission limitations for flares. We also proposed to disapprove provisions of the SIP that allowed certain gas streams at Cenex and ExxonMobil to be burned in the flare.
Summary of Comments and Response
Eleven commenters submitted comments pertaining to our proposal impacting flares. Seven of the commenters opposed and three supported our proposed disapproval of the attainment demonstration for lack of flare limitations. Two commenters opposed and two supported our proposed disapproval of provisions that allowed certain gas streams at Cenex and ExxonMobil to be burned in the flare. One commenter noted that agencies across the country have struggled with flares.
We have considered the comments received and still believe it is appropriate to disapprove the SIP as it applies to the attainment demonstration for lack of flare emission limitations.
The following is a summary of the comments received and our response to the comments:
(1)
Comment:
Several commenters (State letter, document # IV.A-23, comment # 3; YVCC letter, document # IV.A-29; Zaidlicz letter, document # IV.A-30) stated that the attainment demonstration is incomplete without flare limitations. Several commenters (State letter, document # IV.A-23, comment # 3; Conoco letter, document # IV.A-28) stated that the State's current flare provisions should be or have been sufficient. Other commenters (Conoco letter, document # IV.A-24; ExxonMobil letter, document # IV.A-28; MSCC letter, document # IV.A-19, comment #'s 55, 76; MSCC letter, IV.A-20, comment # 7; Cenex letter, document # IV.A-26) stated we are mistaken in disapproving the attainment demonstration because the SIP lacks flare emission limitations and that we did not provide a valid reason for the proposed disapproval or why flares must have specific emission limitations. One commenter (MSCC letter, IV.A-20, comment #'s 7B, C and D) stated that our disapproval of the attainment demonstration for lack of enforceable flare limitations even though flares are modeled is in error and that the modeling of the flares provides a small degree of conservatism in the modeling and is an exercise of state discretion for determining the background SO2 concentrations.
Response:
We continue to believe that the SIP as it applies to the attainment demonstration is not approvable since it does not have enforceable limitations on flares. Additionally, we believe our rationale in the proposed approval (64 FR 40801 of our July 28, 1999 proposal) provided a simple and logical reason why the attainment demonstration should not be approved and why flares must have emission limitations. We have not reviewed the State's current flare provisions because they were never submitted to us for review or approval. However, we did review and comment on earlier versions of the flare provisions that the State had adopted.
In the following documents we provided comments on earlier flare provisions adopted by the State: December 15, 1994 letter from Douglas M. Skie, Chief, Air Programs Branch, EPA, to Jeffrey Chaffee, Acting Administrator, Air Quality Division, Montana Department of Health and Environmental Sciences (
see
document # IV.C-17); April 19, 1995 letter from Douglas M. Skie, Chief, Air Programs Branch, EPA, to Jeffrey Chaffee, Administrator, Air Quality Division, Montana Department of Health and Environmental Sciences (
see
document # IV.C-18); June 3, 1997 letter from Jack W. McGraw, Acting Regional Administrator, EPA, to Mark Simonich, Director, Montana Department of Environmental Quality (
see
document # II.C-8); March 6, 1998 letter from Richard R. Long, Director, Air Program, EPA to Mark Simonich, Director, Montana Department of Environmental Quality (
see
document # II.C-10); and June 5, 1998 letter from Richard R. Long, Director, Air Program, EPA to Mark Simonich, Director, Montana Department of Environmental Quality (
see
document # II.E-7).
(2)
Comment:
Several commenters (Conoco letter, document # IV.A-24; American Petroleum Institute letter, document # IV.A-25; Cenex letter, document # IV.A-26; ExxonMobil letter, document # IV.A-28; MSCC letter, document # IV.A-19, comment # 55) stated that neither our regulations (40 CFR 51.281) nor the Act (section 110(a)(2)(A)) require that all control strategies in the SIP must be federally enforceable; State enforceability is sufficient. One commenter (MSCC letter, document # IV.A-20, comment # 7A) stated our proposed disapproval of the attainment demonstration is in error since flare limitations exist on the State level.
Response:
We do not agree that some of the control strategies adopted by the State do not need to be submitted to us and made part of the federally approved SIP. The general air quality management philosophy is that we establish NAAQS; States develop, and submit to us, control programs to attain and maintain these NAAQS. We either approve or disapprove these control programs and to the extent they are approved they are legally enforceable by us and citizens under the Act.
11
11
See
our TSD (document # III.B-1, at p. 5) and 64 FR 40791 at p. 40805 (document # III.A-2).
This philosophy is reiterated in the General Preamble, 57 FR 13497 (April 16, 1992)
12
(document # II.A-15), at page 13567, right column: “[i]t is important to note that projections of the effect of planned air pollution control measures contained in the SIP's are not merely assumed but are enforced by regulations adopted as part of the SIP. Therefore, if the control measures are not implemented sufficiently to result in required reductions, the State or local agency, or EPA, can take action to enforce implementation of the regulations. This provides a means of achieving, at least in part, the goal of attainment and further progress required in the Act.” The control measures cannot be enforced by citizens and us if the State does not submit them as a SIP revision and we do not make them federally enforceable by our approval of the SIP.
12
The General Preamble, a document we issued following the 1990 Clean Air Act Amendments, describes our preliminary views on how we should interpret various provisions of title I of the Act.
Further, our discussion on the lack of flare emission limitations in our TSD and proposed rulemaking
13
provides citations in 40 CFR part 51 to support the philosophy that all the control measures necessary for attainment and maintenance of the NAAQS must be included as part of the SIP.
13
See
our TSD (document # III.B-1, at p. 37) and 64 FR 40791 at p. 40801 (document # III.A-2).
The commenters point to 40 CFR 51.281 and section 110(a)(2)(A) of the Act as not requiring that every control strategy (relied on for attainment and maintenance of the NAAQS) be included as part of the federally approved SIP. The commenters state that State enforceability of certain control strategies satisfies these provisions. We believe the commenters are reading the Act and CFR incorrectly.
Section 110(a)(2)(A) of the Act says “[e]ach implementation plan submitted by the State under this Act shall be adopted by the State after reasonable
notice and public hearing. Each such plan shall—(A) include enforceable emission limitations and other control measures, means, or techniques * * *, as well as schedules and timetables for compliance, as may be necessary or appropriate to meet the applicable requirements of the Act.” There are several important ideas in this section that the commenters are ignoring. First, the section presumes that the plan is being
submitted
to us. The State enforceable provisions for flares, which the commenters say meet section 110(a)(2)(A), have
not
been submitted to us. Second, the plan that is submitted to us shall contain enforceable emission limitations to meet the applicable requirements of the Act,
e.g.,
show attainment and maintenance of the NAAQS. If a plan is lacking in certain control measures necessary for attainment, then it does not meet section 110(a)(2)(A) of the Act. Finally, the definition of “applicable implementation plan,” in section 302(q) of the Act, supports the notion that the implementation plan is what is submitted and approved by us. The implementation plan, under the Act, does not consist of measures that are only enforceable by the State and were not included in the submission to EPA.
Forty CFR 51.281 indicates that any emission limitations necessary for attainment and maintenance of the NAAQS must be adopted as rules and regulations and be enforceable by the State. The commenters rely on the first sentence of this section as evidence that control measures for attainment and maintenance need only be State enforceable and do not need to be submitted as part of the plan. However, the commenters are ignoring the second sentence of this section which says that “[c]opies of all such rules and regulations must be submitted with the plan.” The definition of “plan,” in 40 CFR 51.100(j), supports the notion that the implementation plan is what is submitted and approved by us. Forty CFR 51.281 and 40 CFR 51.100(j), read together, support the theory that all control measures relied on for attainment and maintenance of the NAAQS
must
be submitted as part of the plan. The implementation plan, under 40 CFR part 51, does not consist of unsubmitted measures that are only State-enforceable.
(3)
Comment
Several commenters (Conoco letter, document # IV.A-24; Cenex letter, document # IV.A-26; ExxonMobil letter, document # IV.A-28) stated that since our modeling guidance in 40 CFR part 52, appendix W, footnote (e) of section 9.1.2 does not require modeling of malfunctions (these are not normal operations and not considered in determining allowable operations when modeling), emissions from flares during operations that are not normal (startup, shutdown, malfunctions and process upsets) should not be considered in determining the allowable emissions when modeling relative to the SIP.
Response:
We agree with the commenters that our modeling guideline in 40 CFR part 52, appendix W, section 9.1.2, footnote (e) indicates that malfunctions are not modeled to determine the allowable limitation. We do not agree with commenters that our modeling guideline explicitly or implicitly does not require the modeling of emissions that result from operations that are not normal and routine or that operation of flares at the Billings/Laurel sources is not normal and routine, at least in part. The 150 lbs/3-hr flare emission limitation used in the attainment modeling does not reflect malfunction emissions, but rather emissions from routine operations at the refineries. Bob Raisch's September 28, 1995 letter to us (document # II.B-18, first page of the enclosure to the letter) says “[t]he Department and each of the refineries estimated that amount of sulfur dioxide which is emitted from each flare during routine operations of the refinery.” Tim Schug's January 22, 1999 letter to us (document # IV.C-12) indicates that a flare is a safety device that is used to manage combustible gases. Mr. Schug also indicates that “[i]n addition, small and continuous quantities of gases may routinely be directed to the flare.” Conoco's comments on our proposal (document # IV.A-24) says “[r]outine emissions are expected to be less than 150 lbs SO2 per 3-hour period * * *” Therefore, it appears that the State and industry agree that emissions from the flares occur on a routine basis.
Thus, for purposes of this action, we need not reach the issue of whether non-routine startups, shutdowns, etc. should be modeled. In this case, the State modeled routine flare emissions assuming they would be limited to 150 lbs of SO2 per 3-hour period, but did not include corresponding emission limits in the SIP submitted to us. This is the basis for our disapproval of the attainment demonstration for lack of flare emission limitations.
(4)
Comment
One commenter (Conoco letter, document # IV. A-24) referred to our concern that if we approved the SIP without making the State-only requirements federally enforceable, the sources could direct emissions from other process units to the flares to avoid violating any emission limitation or other requirement. Further, we indicated that it did not appear that sources could be penalized through the SIP if such circumvention occurred. Conoco stated that these concerns are misplaced since Montana Regulations and the “Other Minor Sources” provision of the stipulations prevent this. Two other commenters (YVCC letter, document # IV.A-29; Zaidlicz letter, document # IV.A-30) stated flares could be used to circumvent other emission limitations.
Response:
In our proposed action we indicated that if there were no emission limitations on flares it appeared that sources could direct emissions from other process units to the flare to avoid violating an emission limitation or other requirement. We indicated that it did not appear that sources could be penalized through the SIP if such a circumvention occurred. One commenter stated our concern was misplaced because of existing State regulations and the “Other Minor Sources” provisions in the SIP.
The “Other Minor Sources” provision in the SIP does not alleviate our concern because this provision addresses the emissions of sulfur bearing gases from other minor sources which
are not
otherwise subject to the SIP. Our concern assumes that emissions being diverted to the flare
are
otherwise subject to the SIP.
We assume that the commenter is referring to the State's circumvention regulation as “existing State regulations.” The State's circumvention regulation, approved into the SIP, states, “(1) No person shall cause or permit the installation or use of any device or any means which, without resulting in reduction in the total amount of air contaminant emitted, conceals or dilutes an emission of air contaminant which would otherwise violate an air pollution control regulation.” Based on the title, it seems that the State's circumvention regulation should address the concern we raised. However, after further review of the regulation we are not convinced that it could prevent sources from directing emissions from other process units to the flare to avoid violating an emissions limitation or other requirement.
Therefore, we continue to believe that establishing emission limitations on flares or some other enforceable mechanism is necessary to prevent sources from redirecting emissions to the flare in order to avoid violating emission limitations elsewhere.
(5)
Comment:
Several commenters (Conoco letter, document # IV.A-24; American Petroleum Institute letter, document # IV.A-25; Cenex letter,
document # IV.A-26; ExxonMobil letter, document # IV.A-28; MSCC letter, document # IV.A-19, comment #'s, 55, 75, 76, 118; MSCC letter, document # IV.A-20, comment # 7F; Goetz letter, document # IV.A-18, exhibit C) stated that other SIPs do not limit emissions from flares, that this SIP should not either, and that our action here is arbitrary. One commenter (MSCC letter, document # IV.A-20, comment #'s 7E, 7F) stated our proposal to disapprove the attainment demonstration was in error because flare limitations are not required federally and flares are not stacks. One commenter (Goetz letter, document # IV.A-18, exhibit C) found that the Utah, Washington and Wyoming SIPS do not require limitations on flares. Finally, one commenter (MSCC letter, document # IV.A-19, comment #'s 77, 118) stated that if we determine that the Billings SIP is inadequate because of the lack of flare limitations we need to determine that all SIPs are inadequate and do a national rulemaking.
Response:
We do not agree that just because other SIPs may not have limitations on flares that the Billings/Laurel SO2 SIP should not either. We believe that when an area has been determined to not be attaining the NAAQS, it is reasonable to apply extra measures to assure that the area attains and maintains the NAAQS. Since the State identified a concern with flare emissions and included the emissions in the attainment demonstration, we believe it is reasonable to make restrictions on flares federally enforceable. With respect to Utah, the commenters are correct that the federally approved PM-10 SIP for Salt Lake and Utah Counties does not contain SO2 flare emission limits.
14
We have identified this as an issue with the Utah PM-10 SIP and are working with the State to address the issue. Wyoming does not contain any SO2 nonattainment areas, and the one PM-10 nonattainment area, Sheridan, does not contain any refineries. Washington does not have any SO2 nonattainment areas. However, the Tacoma PM-10 nonattainment area in Washington does contain a refinery (
see
document #IV.C-14). EPA found in our October 12, 1994 (59 FR 51506) and October 25, 1995 (60 FR 54599) approvals of the PM-10 SIP for Tacoma that it is unlikely that precursors of PM-10 contribute significantly to PM-10 levels which exceed the NAAQS in that area. PM-10 precursor emissions (SO2) were not controlled as part of this SIP.
14
In PM-10 nonattainment areas, the control requirements applicable to major stationary sources of PM-10 also apply to major stationary sources of PM-10 precursors unless we determine such sources do not contribute significantly to PM-10 levels in excess of the NAAQS in that area (
see
section 189(e) of the Act). The General Preamble (document # II.A-15) contains guidance addressing how EPA intends to implement section 189(e) of the Act (
see
57 FR 13539-13540 and 13541-13542). In the Utah PM-10 SIP, SO2 emissions at sources were controlled because SO2 is a precursor of PM-10.
Therefore, although commenters cite specific examples of states near Montana that do not limit SO2 emissions from flares, we believe the situation in the Billings/Laurel area is sufficiently different to warrant the establishment of SO2 limitations on flares.
For the same reasons stated above, we do not agree that we need to do a national rulemaking to require that all SIPS contain limitations on flares.
Finally, we do not agree that flare limitations are not required on a federal level. What is required on a federal level are emission controls that will assure attainment of the NAAQS. In this particular case, since the attainment demonstration assumes flare emissions were controlled we believe the SIP should contain federally enforceable emission limitations on flares. With respect to the comment that flares are not stacks, the commenter is correct in that our definition of stack in 40 CFR 51.100(ff) indicates that flares are not included. However, just because an emission point is not a stack by definition does not mean that the emission point should not be controlled. There are numerous examples of fugitive emissions, which are not emitted from stacks, being controlled in SIPS.
See, for example,
the East Helena Lead SIP which was approved at 66 FR 32760 (June 18, 2001); the SIP establishes emission limits and work practices for loading, unloading and movement of material containing lead, for emissions from buildings, and for emissions from roads and parking lots on and off the facility property.
(6)
Comment:
Several commenters (Conoco letter, document # IV.A-24; Cenex letter, document # IV.A-26; MSCC letter, document # IV.A-20, comment # 7G) stated that instead of disapproving the SIP, flare emissions should be removed from the attainment demonstration. One commenter (MSCC letter, document # IV.A-20, comment # 7G) stated that flare emissions should be included with other background sources.
Response:
We do not agree that the appropriate way to address flare emissions is to “sweep them under the carpet” or incorporate them with background sources. As mentioned above, it is widely accepted that routine emissions occur at flares. The State was concerned enough about these emissions that it chose to regulate them at the State level and considered them in the attainment demonstration. We believe that turning our back on an issue simply because it is difficult to address is not appropriate under the Act. The Act presumes that states will develop an appropriate mix of controls to protect air quality. The State identified the flares as an attainment issue. If the flares are not limited by enforceable limitations, attainment will not be assured.
(7)
Comment:
Several commenters (American Petroleum Institute letter, document # IV.A-25; Cenex letter, document # IV.A-26; Montana Petroleum Association letter, document # IV.A-27; MSCC letter, document # IV.A-19, comment #'s 55, 76) stated that flares are primarily emergency relief devices and limiting flares puts a refiner in an untenable position of having to choose between possible limitation violations or endangering the plant or its workers. These commenters also stated that flare use is essential and no reasonable alternative exists.
Response:
Our proposed action is not intended to jeopardize the safety of refineries, their workers, or neighbors. Our SIP policy
15
has long recognized that imposing penalties for violations of emission limitations for sudden and unavoidable malfunctions caused by circumstances entirely beyond the control of the owner or operator may not be appropriate. States and EPA have the ability to exercise enforcement discretion to refrain from taking enforcement action in these circumstances.
15
See
document # IV.C-13, September 20, 1999 memorandum entitled “State Implementation Plans: Policy Regarding Excess Emissions During Malfunctions, Startup, and Shutdown.” This policy updates previous EPA policy, dating back to 1982, on this issue.
However, we are not convinced that flare use is always essential or that no reasonable alternative exists. We know that other refineries, either because of enforcement action or a company decision, have reduced flaring through better operation and maintenance procedures throughout the refinery and/or by installing flare gas recovery systems to compress and recycle to the gas plant(s), gases that had previously been sent or released to the flare.
See
EPA's Enforcement Alert entitled “Frequent, Routine Flaring May Cause Excessive, Uncontrolled Sulfur Dioxide Releases,” Volume 3, Number 9, EPA 300-N-00-0014 (revised), October 2000 (document # IV.C-72).
(8)
Comment:
Several commenters (American Petroleum Institute letter,
document # IV.A-25; Goetz letter, document # IV.A-18, exhibit C; MSCC letter, document # IV.A-19, comment #'s 55, 75) stated that since measuring flow and concentration of hydrogen sulfide of the gas stream flowing to the emergency flare is very difficult, the flares should not be controlled.
Response:
We do not agree. First, we are not convinced that measuring flow and content of the flare is impossible. We are evaluating potential methods for measuring flare flow and content in preparation of our FIP. Second, other means are available to determine SO2 emissions from flares apart from measuring flare flow and content. To meet the “State-only” requirements for flares it appears that the refineries and MSCC are calculating SO2 emissions based on good engineering judgement.
(9)
Comment:
Several commenters (American Petroleum Institute letter, document # IV.A-25; Cenex letter, document # IV.A-26; ExxonMobil letter, document # IV.A-28; Montana Petroleum Association letter, document # IV.A-27; Conoco letter, document # IV.A-28) stated our action is precedent-setting and more data should be collected to justify the costs and the benefits of imposing emergency flare limitations.
Response:
At this point we are not imposing flare limitations; we are disapproving the attainment demonstration for lack of flare emission limitations.
(10)
Comment:
Several commenters (Cenex letter, document # IV.A-26; American Petroleum Institute letter, document # IV.A-25; MSCC letter, document # IV.A-19, comment # 75; Conoco letter, document # IV.A-28) stated the emissions from flares are inconsequential based on the potential to emit levels in the SIP modeling and have little ambient impact. Two commenters (YVCC letter, document # IV.A-29; Zaidlicz letter, document # IV.A-30) stated SO2 emissions from flaring are significant. Other commenters (ExxonMobil letter, document # IV.A-28; American Petroleum Institute letter, document # IV.A-25; Conoco letter, document # IV.A-28) stated that SO2 emissions and ambient concentrations are at an all-time low and the imposition of extraordinary flare limitations is unnecessary.
Response:
We do not agree that flare emissions are inconsequential and have little ambient impact.
The State modeled emissions from flares at 150 lbs of SO2/3-hours. This 3-hour modeled value equates to 219 tons of SO2/year for each source (((150 lbs SO2/3-hrs) * (8 3-hr periods/day) * (365 days/year))/(2000 lbs/ton)). A major source in a nonattainment area, under 40 CFR section 51.165, is a source that emits 100 tons per year or more of a pollutant subject to regulation under the Act. Under 40 CFR section 51.166, a major source in an attainment area, is a source that emits 100 tons per year or more of a pollutant subject to regulation under the Act if the source is a listed source category (refineries are a listed source category) and 250 tons per year or more of a pollutant subject to regulation under the Act if it is not a listed source category. Under the Title V operating permit regulations, 40 CFR section 70.2, a major source is a source that emits or has the potential to emit 100 tons per year or more of any pollutant. Therefore, based on our regulations, the modeled emissions from flares at each source, in and of themselves, are considered major. Also, as part of the attainment demonstration, the State assumed each of the refineries and MSCC had one flare; the cumulative flare emissions from all sources is 876 tons of SO2/year. We do not think flare emissions are inconsequential.
Also, there is the real possibility that flares emit more than the modeled SO2 level. Following its flare velocity and energy performance test, Conoco estimated flare emissions from the flare header at its Billings refinery at approximately 91 lbs of SO2/hour (
see
document # IV.C-2). This is equivalent to 399 tons of SO2/year.
Regarding the ambient impact of flare emissions, Bob Raisch's September 28, 1995 letter to us (document # II.B-18, first page of the enclosure to the letter) indicates that “[t]he inclusion of routine flare emissions actually required lowering of the emission limitations at other sources within the refinery.” Based on this statement, we believe that flares do have significant ambient impact.
(11)
Comment:
One commenter (Cenex letter, document # IV.A-26) stated that over-reliance on or misapplication of three of our policy memoranda pertaining to excess emissions during startup and shutdown (
i.e.,
the Bennett/Rasnic memos) has contributed to our concerns about the flare issue. Another commenter (MSCC letter, document # IV.A-19, comment #'s 55, 75) stated we cannot apply startup, shutdown and malfunction policy to events that cannot reasonably be controlled; that flares must be used during maintenance activities and neither industry nor the State agree with our interpretation that startup, shutdown and malfunction are avoidable.
Response:
We do not agree that our flare concerns stem from any over-reliance on or misapplication of our policy pertaining to excess emissions during startup, shutdown and malfunction. Our proposed disapproval of the SIP stems from the fact that gas streams are sent routinely to the flare to be burned, causing SO2 emissions from flares. The attainment demonstration assumes that flares are limited yet the SIP submitted by the State does not contain limitations on flares. Therefore, we believe that attainment of the SO2 NAAQS cannot be assured without limitations on flares.
Earlier versions of the State's SIP (those submitted prior to the July 1998 submittal) contained exemptions from the flare limitations for startups, shutdowns and malfunctions. We were concerned about the automatic exemptions to emission limitations because attainment and maintenance of the SO2 NAAQS cannot be assured if exemptions to limitations are allowed. However, since the State removed the flare provisions from the SIP submitted to us, our concerns about startup, shutdown and malfunction were mooted. Note that our policy on excess emissions during startup, shutdown and malfunctions has been reaffirmed and reissued (document # IV.C-13).
(12)
Comment:
One commenter (MSCC letter, document # IV.A-19, comment #75) stated we insisted that the State model flares and that we objected long after the State made clear it would not regulate flare emissions.
Response:
We do not recall requiring the State to model flares. Our recollection is that we deferred to the State's judgement as to which flares should be explicitly modeled.
Also, EPA did not wait until the last minute to voice concerns about flares. Our initial comments on the flare provisions date back to December 1994. In the following documents we provided comments on the flare provisions: December 15, 1994 letter from Douglas M. Skie, Chief, Air Programs Branch, EPA, to Jeffrey Chaffee, Acting Administrator, Air Quality Division, Montana Department of Health and Environmental Sciences (
see
document # IV.C-17); April 19, 1995 letter from Douglas M. Skie, Chief, Air Programs Branch, EPA, to Jeffrey Chaffee, Administrator, Air Quality Division, Montana Department of Health and Environmental Sciences (
see
document # IV.C-18); June 3, 1997 letter from Jack W. McGraw, Acting Regional Administrator, EPA, to Mark Simonich, Director, Montana Department of Environmental Quality (
see
document # II.C-8); March 6, 1998 letter from
Richard R. Long, Director, Air Program, EPA to Mark Simonich, Director, Montana Department of Environmental Quality (
see
document # II.C-10); and June 5, 1998 letter from Richard R. Long, Director, Air Program, EPA to Mark Simonich, Director, Montana Department of Environmental Quality (
see
document # II.E-7).
(13)
Comment:
One commenter (MSCC letter, document # IV.A-19, comment #75) stated the State carefully considered this and determined flares should not have federal limitations. Another commenter (McGarity letter, document # IV.B-1) stated that regulating emissions from flares is a technical area that state agencies around the country have struggled with. There are many valid technical difficulties associated with monitoring and controlling emissions from flares.
Response:
We do not agree with the commenter that the State carefully considered the flare issue and determined flares should not have federal limitations. Based on the State's comments submitted in response to our proposed action (
see
document # IV.A-23), the commenter is not representing the State's position accurately.
In its comments to our proposed action (
see
document # IV.A-23, comment #3) the State said, “[t]he State agrees with EPA that the SIP is incomplete without enforceable emission limitations applicable to flares, and that such limitations should correspond to the emission rates used in the attainment demonstrations. However, after significant effort to address the issue, the State was unable to find a workable solution that would meet EPA's concerns.”
We agree with the commenter that it appears that state agencies across the country have struggled with limiting emissions from refinery flares. However, as indicated in response to comment # 7, above, it appears that there have been recent strides in reducing and measuring emissions from flares.
(14)
Comment:
Two commenters (Cenex letter, document # IV.A-26; ExxonMobil letter, document # IV.A-28) stated that we should not disapprove the provisions that allow the burning of certain gas streams at Cenex and ExxonMobil in the flare because ExxonMobil and Cenex have a way to account for the emissions and under the State-only provisions the flare emissions are limited. Two commenters (YVCC letter, document # IV.A-29; Zaidlicz letter, document # IV.A-30) agree that sour water stripper emissions, if burned in the flare would be unregulated. These commenters stated that sour water stripper emissions should be sent to a sulfur recovery unit instead of burned in a combustion unit.
Response:
We proposed to disapprove provisions of the SIP that allow Cenex and ExxonMobil to burn sour water stripper emissions in the flare (in Cenex's exhibit sections 3(B)(2) and 4(D), only as they apply to flares, and in ExxonMobil's exhibit sections 3(E)(4) and 4(E), only as they apply to flares). Commenters stated we should not propose to disapprove these provisions since Cenex and ExxonMobil have methods to determine SO2 emissions when these specific gas streams are burned in the flare. Although we understand that the SIP provides a means to determine SO2 emissions when these gas streams are burned in the flare, the flare does not have any limitations that are enforceable under the federal SIP. Therefore, although the SO2 emissions from the gas streams burned in the flare can be accounted for, the emissions are not limited. We believe that attainment of the SO2 NAAQS can not be assured without enforceable limitations on the flare. We continue to believe that the provisions that allow the burning of sour water stripper emissions in Cenex and ExxonMobil's flare should be disapproved. However, in this action we cannot require that the sources be prohibited from burning sour water stripper emissions in a combustion unit or that they send the sour water stripper emissions to the sulfur recovery unit. We can only approve or disapprove the SIP as submitted by the State. Likewise, we cannot create any new requirements by our action on the SIP.
(15)
Comment:
Several commenters (Conoco letter, document # IV.A-24; Montana Petroleum Association letter, document # IV.A-27; ExxonMobil letter, document # IV.A-28) recommend that we conditionally approve, rather than disapprove, the SIP as it applies to flares, so that differences between us and the State can be worked out.
Response:
We cannot conditionally approve the SIP with respect to flares unless the Governor of Montana commits to revise the SIP to address our concerns.
See
section 110(k)(4) of the Act. At this time we have not received such a commitment.
D. Dispersion Modeling
Based on our regulations and the characteristics of the Guideline models in appendix W, in our proposed rulemaking we found that the State of Montana used the appropriate computer models for analyzing the adequacy of the existing SIP and for setting emission limitations in the SIP revision to protect the SO2 NAAQS. However, for several reasons discussed in our proposed rulemaking and TSD we proposed to disapprove the attainment demonstration.
Summary of Comments and Response
Two commenters believed that the dispersion modeling that formed the basis for both the 1993 letter and the attainment demonstration was invalid. Two commenters also proposed using other models for attainment demonstration purposes. One commenter wanted us to acknowledge that there were two modeling attainment demonstrations; one for the Laurel area and one for the Billings area.
We have reviewed the comments received and still believe that Montana used the appropriate computer models for analyzing the adequacy of the existing SIP and for setting emission limitations in the SIP revision to protect the SO2 NAAQS. We also acknowledge that there are two modeling demonstrations.
The following is a summary of the comments received and our response to the comments:
1. Validity of the Computer Models
(a)
Comment:
Two commenters (MSCC letter, document # IV.A-19, comment # 1; MSCC letter, document # IV.A-20, comment # 8.B; Goetz letter, document # IV.A-18, exhibit D, comment # III, p. 43) stated that computer modeling of SO2 concentrations in the Billings/Laurel area was invalid because the models used by the State were screening models that over-predict concentrations. One of the commenters (MSCC letter, document # IV.A-20, comment # 3D) stated that EPA's conclusion that the existing SIP was inadequate was not based on the output of an Appendix A model.
Response:
We do not agree with the commenters that only screening models were used. We also disagree with the assertion that EPA's SIP Call was not based on the output of an appendix A model. Appendix A to appendix W of part 51, Summaries of Preferred Air Quality Models, provides key features of refined air quality models preferred for specific regulatory applications. In the modeling studies for both the SIP Call and the attainment demonstration of the revised SIP, an analysis was performed using the modeling techniques and data bases recommended in our “Guideline on Air Quality Modeling (Revised)” (“EPA Guideline” or “Guideline”). Our Guideline is found in 40 CFR part 51, appendix W.
Two Guideline models were used. For “simple terrain” below the tops of stacks, the ISC2 model was used. ISC2,
a revised version of ISC, is a refined dispersion model that is preferred by EPA for a wide range of regulatory applications in simple terrain.
See
40 CFR part 51, appendix W, section 4.1.a and appendix A to appendix W. ISC2 was listed in appendix A to the Guideline at the time the modeling analyses for the Billings/Laurel SIP were performed. (The current version of the Guideline lists ISC3 as a preferred model.
See
40 CFR part 51, appendix A to appendix W, A.5. ISC3 is a more refined version of ISC2 and did not exist at the time of the modeling analyses for the Billings/Laurel area.) For terrain above the tops of stacks, COMPLEX I was used. This is a preferred screening technique, which is incorporated into ISC2 to evaluate concentrations of SO2 in “complex terrain.”
See
appendix W at section 5.2.1. A screening model may over-predict concentrations or may under-predict concentrations in comparison to concentrations that will actually occur in the future. COMPLEX I is not an appendix A model; however, as mentioned above, it is part of ISC2/ISC3 which is an appendix A model. Section 5.2.1.a of the Guideline indicates that for complex terrain any of the identified screening techniques (including COMPLEX I) may be used consistent with the needs, resources and available data of the user. Section 5.2.2.a of the Guideline indicates that when results of the screen analysis demonstrate a possible violation of the NAAQS or the controlling PSD increments, a more refined analysis may need to be conducted. For reasons discussed later in this section, a more refined model could not be applied for complex terrain in the Billings/Laurel area.
(b)
Comment:
One commenter, (MSCC letter, document # IV.A-19, comment # 6) stated that modeling is required under the Act only for reports to Congress and for prediction of the effect of emissions (presumably from new sources)—not for determination of SIP adequacy.
Response:
The statutory provision that authorizes the use of modeling is not limited as the comment suggests. Section 110(a)(2)(K) of the Act requires that all SIPs must
provide for—
(i) the performance of such air quality modeling as the Administrator may prescribe for the purpose of predicting the effect on ambient air quality of any emissions of any air pollutant for which the Administrator has established a national ambient air quality standard, and
(ii) the submission, upon request of data related to such air quality modeling to the Administrator.
By its terms, this provision does not limit the use of modeling to making reports to Congress or permitting new sources. An essential function of air quality modeling is determination of SIP adequacy; so, too, is the establishment of emission limitations for existing sources as part of SIP development. Air quality modeling is, in fact, the only reliable means of determining the adequacy of an SO2 SIP to protect the NAAQS, as will be explained in more detail below.
(c)
Comment:
Two commenters (MSCC letter, document # IV.A-19, comment # 107; Goetz letter, document # IV.A-18, exhibit D, comment #'s III.C, p. 46, and III.F, p. 55) stated that the models should have been validated in the Billings/Laurel area.
Response:
As EPA Guideline models, ISC2 and COMPLEX I have been standardized and validated through scientific study and application in many areas of the country. We authorize the direct use of Guideline models in regulatory applications such as SIP Calls and SIP development, “without a formal demonstration of applicability” in the local area, as long as the models are used as directed in appendix W.
See
58 FR 38816, 38825 (July 20, 1993) (rulemaking by which our modeling guideline was codified as a regulatory requirement).
Validation of the model in the local area where it will be applied is not required for any of the standardized Guideline models or approved screening techniques. On-site validation is required only for alternative models, which are proposed by industry or states to be used in lieu of our Guideline model. Industry in the Billings/Laurel area and the State of Montana did not propose to collect the necessary air quality/meteorological data and perform the statistical performance evaluation and comparison of models that would be necessary to apply an alternative model for the Billings/Laurel area SIP revision. If an alternative model could be shown to perform better than ISC2/COMPLEX I, it would yield somewhat more accurate predictions of ambient impacts of SO2 emissions, but such an effort would require a minimum of one year of on-site data gathering and considerable expense in research costs. The results of such a study could dictate the need for either higher or lower emission control limitations.
(d)
Comment:
Two commenters (MSCC letter, document # IV.A-20, comment #'s 3.G and 3.S; Goetz letter, document # IV.A-18, exhibit D, comment # III.C, p. 46) stated that a prior agreement (1977 Stipulation) required the State to validate any models used in the Billings/Laurel area, but that the State's 1984 studies showed that the model used was “invalid” for the area. The model determined to be invalid in 1984 is being used in the Billings/Laurel area now. The MDEQ has completed a “performance evaluation” of the model, not a validation study. One of the commenters (Goetz letter, document # IV.A-18, comment # III, p. 43) stated that, in response to a SIP Call based on defective modeling, the State developed a SIP based on defective modeling.
Response:
Although our regulations do not require local validation of the models (see D.1.(c), above), MDEQ did perform an evaluation study in the Billings/Laurel area in 1994, using monitoring data to determine how accurately the models were performing. The evaluation study compared monitored data with modeled predictions for the same site. The evaluation study showed that model performance by ISC2 and COMPLEX I exceeded the levels of accuracy that we expected for this application and exceeded the performance of the models in similar tests elsewhere in the country. We do not believe the SIP Call and subsequently developed SIP are based on defective modeling.
See
also the response to Comment (g), below.
(e)
Comment:
One commenter (Goetz letter, document # IV.A-18, exhibit D, comment # III.F, p. 56) stated that the 1994 evaluation study showed a failure to correlate modeled results and monitored data at 13 of 88 data points.
Response:
The evaluation study showed that the model passed the statistical test at 75 data points, an acceptable level. Moreover, the study showed that the ISC2/COMPLEX I model predicted concentrations within plus or minus 20 percent of monitored levels. This is an unusually high correlation. We would expect errors in the highest estimated concentrations of plus or minus 10 to 40 percent to be typical for models of this type.
See
the Guideline on Air Quality Models, appendix W at 10.1.2. (We would not expect the study to predict concentrations within a “factor of two,” the correlation which the commenter (Goetz letter, document # IV.A-18, exhibit D, comment # III.A, p. 44) attributed to us as an acceptable test of model performance.) Where the model failed the test, MDEQ attributed the discrepancy to an underestimate of actual SO2 emissions at Cenex, not a flaw in the model itself.
(f)
Comment:
One commenter (Goetz letter, document # IV.A-18, exhibit D, comment # III.F) also stated that ISC2
should have been evaluated in elevated terrain near the tops of stacks.
Response:
Such an evaluation might be possible in an area that has a single source with only one or a few stacks. Because of the large number of stacks in Billings, all at different elevations, it would be impossible to establish a single value for “stack-top” elevation; such a study would not be meaningful. In any case, a local validation study is not required for a nationally validated model, such as ISC2/COMPLEX I.
(g)
Comment:
Two commenters (MSCC letter, document # IV.A-20, comment #; Goetz letter, document # IV.A-18, exhibit D, comment # III.C, p. 46) stated that MDEQ conducted a validation study of COMPLEX I in the Billings/Laurel area in 1983-84 and that the model failed miserably.
Response:
Having reviewed the test report (
see
document # IV.A-17, exhibit # 88), we conclude that this was not a true validation study. A true validation study of COMPLEX I would involve placing large numbers of temporary monitors, called “sampling bags,” on nearby hillsides and measuring the impacts of tracer gases emitted from individual stacks to determine which stacks are impacting which areas of elevated terrain. The data collected from the array of monitors would then be compared with modeled predictions based on real-time measured emissions from all the sources. We conducted studies of this kind, at great expense, to validate COMPLEX I and other dispersion models on a national level in the 1980's. Our validation studies showed that COMPLEX I did not perform as well as refined models, but performed well enough to serve as a screening tool for use in valley areas with multiple stacks, like the Billings/Laurel area.
The State study in 1983-84 used the existing limited monitoring network of seven monitors, few of which were located in elevated terrain. Tracer gases were not employed, and SO2 emissions estimates for the Billings sources were unreliable at the time. The MDEQ's conclusion that COMPLEX I was not appropriate for modeling sources in Billings, as reported by one commenter (Goetz letter, document # IV.A-18, exhibit D, comment III.C, p. 46), was based on an inadequate evaluation and is not pertinent to the validity of the SIP Call or the attainment demonstration.
(h)
Comment:
One commenter (Goetz letter, document # IV.A-18, exhibit D, comment III.E, pp. 51-54) cited case law to support his assertion that the computer models that were used to develop the SIP for the Billings/Laurel area required on-site validation.
Response:
The cases cited in the comment are concerned with the less reliable models that predated the standardized Guideline models now incorporated into appendix W. For example, in
State of Ohio
v.
United States
EPA, 784 F.2d 224 (6th Cir. 1986), the Sixth Circuit held that EPA arbitrarily relied on the CRSTER computer model to set air pollution limitations for two electric utility plants on Lake Erie. The CRSTER model, now obsolete, was used to predict concentrations of SO2 over the Lake under unusual meteorological and topographic conditions for which the model had not been validated. The facts in the
Ohio
case distinguish it from the Billings/Laurel area SO2 SIP. Unlike the CRSTER model, the models used for the Billings/Laurel area have performed well in similar applications elsewhere in the country involving similar topographic features and similar meteorological characteristics. There are no unusual conditions in the Billings/Laurel area that would tend to undermine the reliability of ISC2 and COMPLEX I; on-site validation would be redundant.
(i)
Comment:
One commenter (MSCC letter, document # IV.A-20, comment # 8.A) stated that models must take into account the unique characteristics of the area where they are used and that modeling for the Billings/Laurel SIP failed to take the area's unique characteristics into account.
Response:
Modeling for the SIP considered all Billings/Laurel area sources, stack parameters, building dimensions, emission rates, terrain elevations, and five years of continuous meteorological data collected at a representative location. We believe that this data set adequately accounts for the unique characteristics of the area.
(j)
Comment:
One commenter (Goetz letter, document # IV.A-18, exhibit D, comment # III.E. p. 52) quoted the
State of Ohio
opinion as supporting the position that “EPA's own guidelines” recognize the importance of validating a model with monitored data from the local area.
Response:
The “guidelines” referred to have been superseded. The court was referring to the 1978 version of the
EPA Guideline on Air Quality Models 6,
which did encourage local validation. This version was superseded in 1986 by an extensive revision of the Guideline. At that time, we conducted national validation studies on all existing computer models and replaced some of them with more reliable models. In 1993, the revised Guideline was incorporated directly into 40 CFR part 51 as appendix W.
See
58 FR 38816 (July 20, 1993).
(k)
Comment:
One commenter (Goetz letter, document # IV.A-18, exhibit D, comment # III.E. p. 53-54) also cited
Cincinnati Gas
&
Electric Co.
v.
Environmental Protection Agency,
578 F.2d 660 (6th Cir. 1978) and
Columbus & Southern Ohio Elec. Co.
v.
Costle
(638 F.2d 910 (6th Cir. 1980) as indicating the necessity for on-site validation.
Response:
In these cases, the Sixth Circuit remanded regulatory decisions to EPA when the agency's model (MAXT-24) used assumptions that were successfully challenged by local studies. The MAXT-24 model, again, has been superseded nationally and is not an EPA Guideline model. These cases do not discredit the application of nationally validated Guideline models, ISC2 and COMPLEX I, in the Billings/Laurel area.
2. Effect of “Contradictory” Monitoring Data
(a)
Comment:
Two commenters (MSCC letter, document # IV.A-19, comment # 1; MSCC letter, document # IV.A-20, comment #'s 3.H and 3.I; Goetz letter, document # IV.A-18, exhibit D, comment #'s III.A and III.B, pp. 44-45) stated that ambient air monitoring is more accurate than computer modeling and that monitoring data for the Billings/Laurel area do not support the models' predicted violations of the SO2 NAAQS. One commenter (MSCC letter, document # IV.A-19, comment # 119) suggested that rather than issuing a SIP Call, we should have questioned how our models or the State's monitors could be so far wrong.
Response:
Monitoring is not more accurate than computer modeling, except for determining ambient concentrations under real-time conditions at a discrete location. Monitoring is limited in time as well as space. Monitoring can only measure pollutant concentrations as they occur; it cannot predict future concentrations when emission levels and meteorological conditions may differ from present conditions. Computer modeling, on the other hand, can analyze all possible conditions to predict concentrations that may not have occurred yet but could occur in the future. As stated in the Guideline on Air Quality Models (“the Guideline”) “[m]odeling is the preferred method for determining emission limitations for both new and existing sources. When a preferred model is available, model results alone (including background) are sufficient.” 40 CFR part 51, appendix W, section 11.2.2. In the usual case, regulators may rely on the results of modeling and are not required to
consider measured data from local ambient monitoring.
(b)
Comment:
One commenter (Goetz letter, document # IV.A-18, exhibit D, comment # III.A, p. 44) stated that monitoring data may reasonably be used as an acceptable technique to demonstrate that the air quality in a region is being protected; monitoring data are facts, while models use assumptions.
Response:
The Guideline states, “Due to limitations in the spatial and temporal coverage of air quality measurements, monitoring data normally are not sufficient as the sole basis for demonstrating the adequacy of emission limits for existing sources.” Forty CFR part 51, appendix W, section 1.0.b. The use of measured data in lieu of model predictions for SIP development is discouraged, because it is impossible to capture worst case conditions, for either emission levels or meteorology, with only a few monitors. Monitored data may be used in certain, limited circumstances and only if monitors are located at points of maximum concentration.
See id.
at section 11.2.2. Even then, locations of maximum concentration may not remain the same, but may change from year to year in response to changes in emission patterns and emission rates from existing sources, installation of new emission sources, and meteorological variability.
Even the most extensive monitoring network does not represent future concentrations of pollutants and thus cannot predict future violations. Modeling, on the other hand, can predict for all possible conditions and can show how well the emission limitations in the SIP will protect air quality under future conditions. Modeling assumes the maximum emission levels allowed under applicable emission limitations and assumes worst case meteorological conditions based on evidence of historical meteorological patterns. Models operate on assumptions, but the assumptions are based on facts. The models analyze the combined effects of the worst case values of the two variables (emission levels and meteorology) on ambient concentrations of pollutants at a multitude of “receptors” or sites, to predict maximum concentrations that may not have occurred yet, but could occur in the future.
In general, appendix W and the Guideline models have been adopted by rulemaking in accordance with the Administrative Procedures Act. They may not be challenged in this action; they could have been challenged only by timely petition to the U.S. Court of Appeals for the D.C. Circuit in accordance with section 307(b) of the Act.
(c)
Comment:
Two commenters (MSCC letter, document # IV.A-19, comment # 1; Goetz letter, document # IV.A-18, exhibit D, comment # III, p. 43) stated that we ignored contradictory information from the monitors in favor of modeling when we issued the 1993 letter, thus invalidating the SIP Call.
Response:
Historically, the seven monitors in the Billings/Laurel area (the State added a new monitor in 1999) have not measured violations of the SO2 standards. We were aware of the non-supportive monitoring information at the time of the 1993 letter and discussed the data in our letter (
see
document # II.G-1). There we cited cases that approve EPA's reliance on modeling results in the face of apparently contrary monitoring data. In
Northern Plains Resource Council
v.
U.S. Environmental Protection Agency
, 645 F. 2d 1349 (9th Cir. 1981), for example, the court held that EPA's reliance on a model would be arbitrary and capricious only if “EPA ignored reliable data that so undermined EPA model projections that reliance on the model was irrational.”
See
645 F.2d at 1362.
In the SIP Call, we are not ignoring reliable data. We analyzed the available monitoring data, compared it with modeling results, and determined that it did not undermine the modeling results because the data had not been obtained at locations where the models predicted maximum concentrations of SO2. In addition, real time monitoring data was available to the operators of some of the industry sources, who could have controlled their operations to avoid NAAQS exceedances when concentrations approached critical levels. For these reasons, we conclude that the lack of monitored violations do not undermine the models' projections.
(d)
Comment:
Two commenters (MSCC letter, document # IV.A-20, comment # 3.L; Goetz letter, document # IV.A-18, exhibit D, comment # III.B, p. 45) stated that, after the 1993 letter, the State moved its monitors to two of the locations where maximum concentrations were predicted, but that these monitors still have not registered violations of the SO2 NAAQS.
Response:
The monitors' failure to register violations is not surprising. Information provided by the sources and MDEQ indicates that actual emissions have declined since 1993. Modeling can analyze the combined effects of the highest allowable emission levels and worst-case meteorological events at numerous receptors to predict violations. Any one monitor is unlikely to measure such synchronous events at a single location. When actual emission levels are lower than allowable emissions and, as in the Billings/Laurel area, are actually declining, monitored levels cannot be expected to match computer modeling results.
In
Northern Plains Resource Council
, the Ninth Circuit observed that monitored data can only be used to validate (or, by implication, invalidate) a model, if the data are collected under the same conditions for which the model is predicting ambient concentrations.
See
645 F.2d at 1364. For the Billings/Laurel SIP Call, the model predicted violations at allowable levels, the maximum levels of emissions permitted under the existing SIP. It is unlikely that the sources in the area were emitting SO2 at maximum allowable levels at the same time, during the most adverse meteorological conditions. Furthermore, even now, monitors are not located at many locations where the SIP Call modeling indicated NAAQS violations. Therefore, the monitoring data were not collected under the same conditions for which the models were predicting violations. Although these conditions may not have occurred yet, they can occur in the future. The SIP Call is necessary to protect the air quality in the Billings/Laurel area now and in the future.
The same point was made in another case,
PPG Industries, Inc.
v.
Costle
, 630 F.2d 462 (6th Cir. 1980). There the court agreed with EPA that “projected future violations may provide the basis for a nonattainment designation in currently clean areas.” 630 F.2d at 464. Contrary monitoring data would not necessarily bar a nonattainment designation (or a SIP Call) based on modeling to protect the NAAQS in the future. The court held that “EPA need only offer record support of the accuracy of the model used.”
Id.
at 467. Record support for the model used for the Billings/Laurel SIP Call is provided by the EPA Guideline, appendix W.
The
PPG Industries
court observed that if EPA based its action on predictions of future violations, “monitored data which merely show historical attainment of air quality standards” do not undermine the agency's decision.
Id.
at 468. The monitored data being offered to contradict modeling results must show that the modeled predictions are “unsupportable.”
Id.
The commenters have not shown that the modeled predictions of violations in Billings/Laurel are unsupportable in comparison to monitoring data, for the reasons already cited—the lack of monitoring
data from locations of predicted maximum concentrations, the lack of monitoring data for impacts of maximum allowable emissions, the possibility that source operators changed operations when feedback from monitors indicated concentrations of SO2 approaching the critical values, and the possibility that sources were emitting at reduced levels when the most adverse meteorological conditions occurred.
3. Usefulness of More Refined Models
(a)
Comment:
Two commenters (MSCC letter, document # IV.A-20, comment #'s 3.T, 3.U, and 8C; Goetz letter, document # IV.A-18, exhibit D, comment #'s III.D.3, pp. 50-51) stated that a more refined computer model should have been used to develop the revised SIP for the Billings/Laurel area. They commented that the CTDMPLUS model, in particular, is more accurate and predicts lower concentrations in areas of complex terrain than COMPLEX I. These commenters pointed out that CTDMPLUS was used instead of COMPLEX I to develop the SO2 SIP for East Helena, Montana.
Response:
The Billings/Laurel area differs in several respects from the East Helena area. East Helena has only one significant source of SO2, the Asarco lead smelter. The smelter has three tall stacks that emit most of the source's SO2. In the Billings/Laurel area, there are seven industrial sources with a combined total of several dozen different stacks that must be modeled. CTDMPLUS is limited in its ability to consider the impacts of more than a few emission points at the same time. The complexity involved in applying CTDMPLUS to develop emission limitations and show attainment for so many different emission points would make the modeling analysis infeasible in the Billings/Laurel area. The complexity of the analysis would also preclude the use of variable emission limitations, which are now in place at some of the Billings/Laurel sources.
In addition, it is not possible to accurately apply CTDMPLUS without a scientifically rigorous set of local meteorological data. Such data were available for East Helena, but not for the Billings/Laurel area. In East Helena, Asarco collected the appropriate on-site meteorological data for use in CTDM-PLUS modeling, including upper air measurements that were representative of conditions at plume height. The meteorological monitoring program was submitted to EPA and MDEQ in August 1992 for approval, and data collection began in May 1993. There are no similar data available in the Billings area for application of CTDMPLUS.
(b)
Comment:
Two commenters (MSCC letter, document # IV.A-19, comment # 54; MSCC letter, document # IV.A-20, document # 3V; Goetz letter, document # IV.A-18, exhibit D, comment #'s III.D.3, p. 51; III.H, p.59) stated that MSCC proposed to gather the necessary meteorological data for the Billings/Laurel area. These commenters asserted that MDEQ's and EPA's failure to approve the proposal resulted in an arbitrary and capricious reliance on an outdated and over-predictive screening model (COMPLEX I).
Response:
MSCC submitted a meteorological monitoring proposal in 1996, nearly three years after the modeling protocol for Billings/Laurel was developed and applied. Within a month of receiving MSCC's meteorological monitoring proposal from MDEQ, we reviewed it and responded that the proposal raised serious problems that could potentially invalidate any data collected.
See
letter from Kevin Golden, EPA, to John Coefield, MDEQ, September 26, 1996 (document # IV.C-28). To our knowledge, the company did not revise and re-submit its proposal.
(c)
Comment:
Two commenters (MSCC letter, document # IV.A-20, comment # 3.U; Goetz letter, document # IV.A-18, exhibit D, comment # III.D.1 and 2, p. 48) stated that MSCC's consultant, Michael Machler, applied CTDMPLUS in modeling tests at a site in Billings called Sacrifice Cliffs, located in elevated terrain. The results were 50-60 percent lower than those predicted by COMPLEX I and were in close agreement with monitoring data at the site, which indicated levels one-half to one-third the concentrations predicted by COMPLEX I.
Response:
One of the commenters (Goetz letter, document # IV.A-18, exhibit D, comment # III.D.3) admitted that meteorological data from East Helena were used for these modeling tests, because the specific data inputs needed for the model were not available for Billings. For CTDMPLUS, unlike ISC2/COMPLEX I, predictions may be very sensitive to changes in upper air meteorological conditions, such as plume altitude, wind, and turbulence. These conditions must be measured locally to generate appropriate data inputs for the model. Using critical meteorological data from another site would invalidate any testing with CTDMPLUS. In addition, a single monitor is insufficient to test any model. In areas such as Billings, where SO2 concentration gradients are high (
i.e.
, a significant change in concentrations between receptor points), a dense monitoring network is necessary to adequately test a model.
16
16
“Interim Procedures for Evaluating Air Quality Models (Revised),” EPA-450/4-84-023, September 1984, page 48 (document # IV.C-78).
(d)
Comment:
One commenter (Conoco letter, document # IV.A-24, p.3) suggested that if we believe the SIP needs to be modeled again to address the modeling concerns EPA raised in the proposed rulemaking, we should consider using the CALPUFF model for future modeling. The commenter noted that CALPUFF was used in a study in West Virginia and Ohio to establish SO2 controls within the study area. Another commenter (Goetz, document # IV.A-18, exhibit D, comment # III.D.2) stated that MSCC's consultant, Michael Machler suggested that CALPUFF could be used in the Billings/Laurel area.
Response:
We do not agree that CALPUFF should be used in the Billings/Laurel area. CALPUFF is a refined model that has been applied in complex terrain, but is not listed in the Guideline on Air Quality Models as a preferred model. It is not appropriate for regulatory applications, without further study. A similar model, MESOPUFF, is listed in appendix W for evaluating long-range transport issues (
i.e.,
distances greater than 50 kilometers from the source). This model would not be considered appropriate, however, for evaluating near-source impacts, such as those evident in the Billings/Laurel area. Ohio and West Virginia used CALPUFF in a non-guideline application, following the protocol for an on-site modeling evaluation study provided in appendix W, section 3.2 (“Use of Alternative Models”). Alternative models are used on a case-by-case basis, when the EPA Regional Office believes such use is justified. We do not believe that application of CALPUFF is appropriate for the Billings/Laurel area at this time because its applicability has not been established (or even proposed).
(e)
Comment:
One commenter (Goetz letter, document # IV.A-18, exhibit D, comment # III.D.2, p. 49) indicated that Michael Machler, a consultant for MSCC, suggested that another model, AERMOD, be used in complex terrain.
Response:
AERMOD is a new model that was not available when the SIP modeling protocol was developed in 1993. It has been discussed as a possible future replacement for ISC in the modeling Guideline. At this time, it has not been proposed for public review and comment. Reviewing all the facts, we conclude that MDEQ used the best
available models to perform computer modeling for the Billings/Laurel SIP.
(f)
Comment:
One commenter (Goetz letter, document # IV.A-18, exhibit D, comment # III.D, p. 47) stated that the modeling receptor on Sacrifice Cliffs is the most controlling and “drives the entire SIP,” implying that modeling for complex terrain is the most critical element of the attainment demonstration and that a refined model should have been used for complex terrain. The commenter also stated that the most controlling receptors for MSCC, ExxonMobil and YELP are not on Sacrifice Cliffs, but in the hills to the south.
Response:
There are in fact a number of different receptor sites where predicted concentrations of SO2 in the pre-SIP revision scenarios exceeded the SO2 NAAQS, both in complex terrain and in simple terrain. There is not one receptor site that is most controlling for the SIP. Many of the sources in the current SIP attainment demonstration have emission limitations based on predictions from ISC2, the refined EPA Guideline model. Other sources are controlled based on the approved screening model, COMPLEX I.
It is not clear what the commenter means by “controlling receptors” for various sources. As one might expect, the maximum incremental contributions from each source generally were predicted to occur close to that individual source. If a receptor location close to a specific source is predicted to exceed the NAAQS, the State would have the option of controlling emissions from the nearby source, or reducing emissions from the “background sources.” Given the large number of facilities and emission points in the Billings/Laurel area, emission reductions were needed from a number of sources to show NAAQS attainment at all receptors.
(g)
Comment:
One commenter (Goetz letter, document # IV.A-18, exhibit D, comment #'s III.D.3, p.50; III.H, p. 59) stated that using the less refined, less accurate COMPLEX I model for complex terrain for the SIP Call and SIP modeling is entirely arbitrary and capricious.
Response:
COMPLEX I is a Guideline screening model, and its application is appropriate under our regulations as long as it is applied as directed by appendix W. COMPLEX I results may be used for all regulatory purposes unless a refined model is available, which was not the case for the Billings/Laurel area. If any approved model were to over-predict ambient concentrations and call for more restrictive emission limitations than a hypothetical, more refined model, the modeled attainment demonstration would not be invalid. Courts have accepted that a certain level of over-prediction is allowed by the Act. In
Cleveland Electric Illuminating Co.
v.
EPA,
572 F.2d 1150 (6th Cir. 1978)
cert. den.
439 U.S. 910, 99 S.Ct. 278 (1978), for example, the Sixth Circuit approved EPA's reliance on an earlier computer model (RAM) for setting SO2 limitations in a federal implementation plan, even though an industry study showed that the RAM model over-predicted violations and was contradicted by data from ambient monitoring.
The court observed:
SO2 emissions have a direct impact upon the health and the lives of the population of Ohio—particularly its young people, its sick people, and its old people. If the RAM model did over-predict emission rates, such a conservative approach was apparently contemplated by Congress in requiring that EPA plans contain “emission limitations * * * necessary to
insure
attainment and maintenance” of national ambient air standards. 572 F.2d at 1164 (emphasis in original) (citing former 42 U.S.C. section 1857c-5(a)(2)(B), now revised and recodified at 42 U.S.C. 7410(a)(2)).
4. Inputs Used in Computer Models
(a)
Comment:
One commenter (Goetz letter, document # IV.A-18, exhibit D, comment # III.G, pp. 57-58) stated that the use of non-local meteorological data “exacerbates the arbitrariness” of the computer modeling; the commenter objected to the use of data from Great Falls, Montana and from the Billings airport. Another commenter (MSCC letter, document # IV.A-20, comment # 8.D) also criticized us for using non-local data in the models.
Response:
The computer modeling was not rendered unreliable by the use of non-local meteorological data. The modeling protocol that was used for the SIP revision was developed by the State in early 1993 and approved by us in August 1993. The protocol development process included substantial input and comments from the public, including industry groups and their constituents. No meteorological towers or vertical temperature soundings were available in the Billings/Laurel area to provide on-site data for upper air conditions, one component of the meteorological data needed for computer modeling. Instead, MDEQ used representative data from Great Falls, which, although 180 miles from Billings/Laurel, is similarly located on the high plains to the east of the Rocky Mountains. Thus MDEQ made use of available data for upper air conditions that were most representative of the conditions in the Billings/Laurel area. This approach is approved by us.
See
40 CFR part 51, appendix W, section 9.3.
MDEQ used temperature sounding data from Great Falls in the ISC2/COMPLEX I model to determine mixing height. For point source emissions with significant plume rise, such as the emissions from the Billings/Laurel sources, predicted concentrations from ISC2/COMPLEX I are relatively insensitive to changes in mixing height, and use of non-local meteorological data for this purpose would not make a significant difference. CTDMPLUS, by contrast, requires considerably more detailed upper air input information than ISC2. CTDMPLUS predictions may be very sensitive to changes in several conditions that can only be measured with a meteorological tower, such as plume altitude, wind, and turbulence. As we discussed in section V.D.3.a, above, specialized local meteorological data, which were unavailable for the Billings/Laurel area, would be needed to apply this model accurately.
(b)
Comment:
One commenter (Goetz letter, document # IV.A-18, exhibit D, comment # III.G) stated that MDEQ improperly used data from the Billings airport to represent meteorological conditions in the lower atmosphere, that this location is not representative, because it is miles from both the sources and the critical receptors, and that data from the ambient monitors should have been used.
Response:
We agree with MDEQ that the Billings airport data are representative of the area. Meteorological data from the ambient monitors at Lockwood Park, Brickyard Lane, Coburn Road and Laurel were not used because these monitors, located in the Yellowstone River Valley, are subject to variable ground-level conditions and are not representative of conditions affecting plume-height emissions as they are transported over the valley. The most representative data available were those obtained at the airport, which is located on a bluff above the valley, not subject to localized meteorological effects that occur along the valley floor.
(c)
Comment:
One commenter (MSCC letter, document # IV.A-19, comment # 1; MSCC letter, document # IV.A-20, comment #'s 3M, 3O) stated that the SIP Call is flawed because the modeling used factually inaccurate assumptions for emission rates, stack parameters, and other factors.
Response:
The SIP Call modeling used data inputs from an earlier emissions inventory that did contain some errors. These errors were corrected, and the corrected inputs were used in the modeling for SIP development. The SIP
Call modeling showed NAAQS violations at many sites at allowable emission levels. With corrected inputs, the modeling continued to predict NAAQS violations as much as two times over the national standard, thus supporting the SIP Call.
(d)
Comment:
One commenter (MSCC letter, document # IV.A-19, comment # 108) stated that CEMS data now indicate an error in the assumed buoyancy flux for MSCC's main stack; the current modeling protocol contains an assumption which significantly underestimates the average rise in emissions. Any revised modeling should correct this assumption.
Response:
We agree that future modeling should include all corrected data. In any modeling analysis, input data are based on the best available information at the time of the analysis. CEMS measurements of flow and temperature data provide the best estimates of stack parameters, and values based on CEMS data should be used in any future SIP modeling for Billings provided the CEMS data are accurate. Other data inputs have been corrected and added, as we discussed in the TSD for this rulemaking (document # III.B-1). Any future modeling in the Billings/Laurel area should incorporate all corrections. The SIP limitations are based on the best information available at the time the attainment demonstration was modeled, and the same will be true for any FIP limitations that are developed.
(e)
Comment:
MSCC's consultant, Michael Machler, stated that he had identified problems in the past with the way mixing heights are calculated in dispersion modeling. He stated that EPA has apparently corrected the problem and that ISC3, the newer version of the ISC2 model used for the Billings/Laurel SIP, now provides for more accurate calculations of mixing height. The modeling for the SIP used the older version, however, and has not been updated with respect to calculation of mixing heights.
See
Goetz letter, document # IV.A-18, exhibit E, page 1.
Response:
In 1994, when the State performed the modeling for the attainment demonstration, MDEQ used the most accurate information and the best data base available at the time. ISC2 was then the preferred Guideline model. The newer ISC3 is comparatively more refined, but the correction in calculation of mixing heights would not make a significant diff
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