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Citation: 56 Fed. Reg. 5173 1991

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### Federal Register / Vol. 56, No. 27 / Friday, February 8, 1991 / Proposed Rules

Subsequent meetings of the committee and any subcommittees would be held in Washington, DC, orin Ann Arbor, Michigan on a schedule to be determined by the committee. As required by FACA, EPA would publish timely notice ofthe meetings in the Federal Register. The meetings would be open to the public and interested persons would be permitted to file
statements with the committee.

Due to the limited time allowed the Agency topromulgate regulations and guidelines, EPAintends that the meetings would occur every two to three weeks so that consensus may be reached as quickly as possible, in light ofthe Agency's intention to issue proposed reformulated gasoline and oxygenated fuels labeling regulations
not later than May 31, 1991.

VII. Negotiation Procedures

The following procedures and guidelines will apply to the committee, if formed, unless they aremodified as a result ofcomments received on this notice orduring the negotiating process.
A. Facilitator

EPA will use a neutral facilitator. The facilitator will not be involved with the substantive development or enforcement ofthe regulation. The facilitator's role is
to chair negotiating sessions; help the negotiation process run smoothly; and help participants define and reach

consensus.
B. GoodFaithNegotiation

Committee participants must be willing tonegotiate in good faith and be authorized by their respective organizations orinterest groups to do so. Consequently, each entity included on the committee must designate a senior official to represent its interests.

C.AdministrativeSupportandMeetings

EPA's Information and Regulatory System Division will supply logistical, administrative, and management support for the committee. To support the negotiations, EPAwill make available technical support personnel and expertise which it has available to support the committee. Also to support the negotiations, the Agency has pledged funds to a resource pool which the National Institute for Dispute Resolution will administer.EPA expects that funds from private foundations may also be available. The committee may

use the funds for activities such as training, technical support and any other assistance the committee deems useful. To the extent allowed by law, committee members will be free to determine the procedures under which requests for funds will be made and approved.

D. CommitteeProcedures

Under the general guidance and direction ofthe facilitator, and subject
to any applicable legal requirements. committee members will determine the
most appropriate procedures for committee meetings.

E.DefiningConsensus

The goal ofthe negotiating process is
to achieve consensus. In the negotiations completed to date,

consensus has meant that each participant or interest concurs in the result. The NRA defines consensus as unanimous concurrence among the interests represented on the committee, unless the committee agrees to define

consensus to mean a general but not unanimous concurrence or agrees upon another definition.

F Failure ofCommitteetoReach
Consensus

In the event the committee is unable
to reach consensus in the time available for development of the reformulated gasoline and oxygenated gasoline proposed rules and the oxygenated gasoline credit trading guidelines, EPA will proceed with its own approach. Whether nor not consensus is reached, the committee may choose to continue
to meet after publication ofthe proposed rules for purposes offormulating recommendations regarding the proposals for the Agency's consideration. Committee meetings conducted after proposal would be open to the public, committee recommendations would beplaced in the relevant rulemaking dockets, and the dockets would remain open for submission ofresponses to any recommendations made by the committee. However, while consensus positions developed prior to proposal would be the presumptive basis ofthe Agency's proposed rules, any recommendations formulated after proposal would not be the presumptive basis ofthe final rules. The Agency would consider such recommendations along with the public comments received in response to the proposed rules and the recommendations in making its decision on the final rules.

Parties to the negotiation may withdraw at any time. If this happens, the remaining committee members and the Agency will evaluate whether the committee should continue to exist.

G. Recordof Meetings
In accordance with FACA and NRA, EPA will keep a record ofall committee meetings, including minutes ofthe meetings and any records, reports, working papers or other documents made available to or prepared by the committee forthe meetings. This record will be placed in the public dockets identified above.

Dated: February 5,1991. J.Clarence Davies, AssistantAdministrator forPolicy,Planning andEvaluation. [FR Doc.91-3131 Filed 2-7-91; 8:45 am]

BILLING CODE 6560-5-

40 CFR Part 52

[AD-FRL-3700-41
Approval and Promulgation of Implementation Plans: Revisionof the VisibilityFIP forArizona

AGENCY: U.S. Environmental Protection Agency (EPA). ACTION: Proposed rule and
announcement ofpublic hearing.

SUMMARY: This proposal addresses the need for revising the Federal implementation plan (FIP) for the State ofArizona to include emission limits representing best available retrofit technology (BART) for the Navajo Generating Station (NGS) toremedy wintertime visibility impairment in the Grand Canyon National Park (Grand Canyon). This action is taken pursuant to sections 169A and 110(c) ofthe Clean Air Act (Act) which require EPA, upon default by a State, to take appropriate

measures to remedy certified visibility impairments in mandatory Class I areas where the impairment is reasonably attributed to a specific source. On September 5, 1989, EPA preliminarily attributed a significant portion of wintertime impairment to the NGS (54 FR 36948). The timing oftoday's action is inaccordance with a revised settlement agreement between EPA and the Environmental Defense Fund (EDF) in EDFv.Reilly,No. C82-6850 RPA (N. D. Cal.). DATES: Comments on this notice of proposed rulemaking should be submitted to the Central Docket Section

no later than April 19, 1991.

The EPA has received a written request for a public hearing on this action. A hearing has been scheduled for Monday, March 18, 1991, starting at 1
p.m. in the Maricopa County Auditorium, 201 West Jefferson, Phoenix, Arizona. Persons wishing to speak at the hearing should notify the Information Contact by March 11, 1991
at the address given below. 

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### Federal Register / Vol. 56, No. 27 / Friday. February 8. 1991 1 Proposed Rules'

ADDRESSES: Comments 

### should be submitted (in duplicate, ifpossible) to AirDocket (LE-131), Attention: A-89- OZA, U.S. EPA, rm.M1500 Waterside Mall,401 M Street, SW., Washington, DC 20460.

Docket:Pursuant to section 307(d)(1)(B) ofthe Act, 42 U.S.C. 

### 7607(d)[1)(B), this action is subject to the procedural requirements ofsection 307(d). Therefore, EPA has established a docketfor thisnotice, Docket Number A-89-02A. Materials related to the development ofthis notice have been placed in this docket. Materials related to EPAs preliminary attribution ofa significant portion ofthe wintertime visibility impairment in the Grand Canyon to the NGS (54FR 36948 (September 5, 1989)) havebeen placed in Docket A-89-02. For background information, materials related to the development ofthe visibility protection program (40 CFR 51.300 etseq.) are available inDocket A-79-40. Also, materials related tothe development of the visibility new source review (NSR) 

### and visibility monitoring strategies are available in Docket A-84-32. Materials related to thevisibility long-term strategy, implementation ofcontrol strategy, and integral vista program are available In Docket A-85-26. All dockets are available for public inspection and copying between 8:30

a.m. to 12 noon and 1:30p.m. to 3:30p.m. Monday through Friday at EPA's Central Docket Section, Office ofGeneral Counsel, room 1500, 401M Street, SW., Washington, DC. A reasonable fee may be charged forcopies. Copies ofthis Notice, the Guidelines forDetermining BART, theBART Analysis forNGS, the Regulatory Impact Analysis and Addendum, and copies ofthe comments provided by theFederal landmanager (FLM), ifany, are also available for public inspection at:
Department ofEnvironmental Quality,

Office ofAir Quality, 3003 North Central Avenue, suite 1700, Phoenix, Arizona 85012. Department ofEnvironmental Quality,

Northern Regional Office, 2501 North 4th Street,suite 14, Flagstaff,Arizona 86004. City ofPage Municipal Library, 697

VistaAvenue, Page, Arizona 86040.

FOR FURTHER INFORMATION CONTACT:. 

### David H. Stonefield, U.S. Environmental Protection Agency, Office ofAir Quality Planning and Standards, MD-15, Research Triangle Park,NC 27711, (919) 541-5350 orFTS629-5350. SUPPLEMENTARY INFORMATION: 

### Background A. RegulatoryRequirements Section 169A oftheAct, 42U.S.C. 7491, sets as a national goal "the preventation of any future, and the remedying ofany existing, Impairment ofvisibility in mandatory Class I Federal areaswhich impairment results from manmade air pollution." Mandatory Class IFederal areas are certain national parks, wildernesses, and international parks as described in section 162(a) ofthe Act, 42U.S.C. 7472(a). Section 169A requires thatEPA promulgate regulations to assure reasonable progress toward meeting the national goal formandatory Class I Federal areas where EPA has determined that visibility is an important value. On November 30, 1979, EPAidentified 156 areas, including the Grand Canyon in Arizona where visibility is an important air quality related value (44 FR 69122). Section 169A specifically requires EPA to promulgate regulations requiring States to amend their State implementation plans (SIP's) to provide reasonable progress toward meeting the national goal for the 156areas.

OnDecember 2, 1980,EPA promulgated the required visibility regulations (45FR 80084, codified at40 CFR 51.300 etseq.).In broad outline, the visibility regulations require the 36 States listed in §51.300(b), including Arizona, to: (1)Coordinate SIP development with the appropriate FLM's; (2)develop a program to assess and remedy visibility impairment from

new and existing sources; (3) develop a long-term (10 to 15 years) strategy to
assure reasonable progress toward the national goal; (4)develop a visibility monitoring strategy to collect information on visibility conditions; and (5) consider in all aspects ofvisibility protection any "integral vistas" (importantviews oflandmarks or panoramas that extend outside ofthe boundaries ofthe Class Iarea identified by theFLM's as critical to the visitors' enjoyment ofthe Class Iareas. The affected States were required to submit the revised SIPs satisfying these provisions by September 2,1981. See 45 FR 80091, codified at 40 CFR 51.302(a)(1).

The second requirement listed above is ofparticular relevance to today's action. Pursuant to40CFR 51.302(c)(2), each affected State is required to include in its SIP such emission limitations, schedules ofcompliance, and other measures as may be necessary to makereasonable progress toward the national visibility goal.In addition, under 40 CFR 51.302(c)(1), an FLM may certify to a State that there exists impairment ofvisibility in any mandatory Class I Federal area. Pursuant to 40 CFR 51.302(c)(4)(i), where impairment is certified at least 6 months prior to plan submission, an affected State must (1) identify each existing stationary facility which may "reasonably be anticipated to cause or contribute" to any such impairment which is "reasonably attributable to that existing stationary facility," and (2) analyze forBART any facility so identified. "Reasonably attributable" impairment is impairment "attributable by visual observations orany other technique the State seems appropriate" (40 CFR 51.301(s)). Where a State defaults on its obligations under the visibility regulations, EPAmay act in place ofthe State pursuant to a FIP • under section 110(c) ofthe Act, 42 U.S.C. 7410(c). 1 In such cases, all ofthe rights and duties that would otherwise fall to the State accrue instead to EPA.Thus, EPAmay utilize attribution techniques it deems appropriate; must identify "reasonably attributable" sources of impairment, conduct BART analyses, adopt BART requirements; and may promulgate such other control strategies that EPA, in its discretion, deems
necessary to make reasonable progress toward the national visibility goal.

The visibility regulations promulgated
at 40 CFR 51.302(c)(4)(i) require that

once impairment has been certified, a State (or EPAifthe State's visibility protection program addressing BART has not been approved and EPA is acting in its place) must analyze for BART any specific existing stationary facility it identifies as a "reasonably attributable" source ofthe impairment. Pursuant to section 169A(b) ofthe Act (42 U.S.C. 7491(b)) and 40 CFR 51.302(c)(4)(iii), the emission limitation representing BART forfossil fuel-fired
power plants with a generating capacity in excess of750 megawatts (MW) must be determined pursuant to guidelines promulgated by the Administrator. This statutorily-required procedure for conducting a BART analysis is found in "Guidelines forDetermining Best Available Retrofit Technology Analysis for Coal-Fired PowerPlants and Other Stationary Facilities" (EPA-450/3-80- 009b) (BART Guidelines).2 A copy of

ISection 110(c) requries EPA to promulgate FtPs whenever a State fails to submit an implementation plan (or portion thereof) which meets the requirements ofsection 110;the Administrator determines that aplan (orportion) isnot in accordance with the requirements ofsection 110; or the State fails to revise its plan within 60 days after notification bythe Administrator in accordance with section 110(a)(2)(IH).

2As discussed below the Agency is proposing In this rulemaking to make certain modification to these Guidelines. I 

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this document may be found in Docket A-89-02.

InDecember 1982, environmental groups, including EDF,filed a citizens' suit in the United StatesDistrict Court for theNorthern District ofCalifornia alleging that EPA had failed to perform

a nondiscretionary duty under section 110(c) ofthe Act, 42U.S.C. 7410(c), to promulgate visibilityFIPs forthe 35 States 3 

### that,at that time,had failed to submit SIPs to EPA as called for bythe 1980 visibility regulations, EDFv. Reilly, No. C826850 RPA (N.D. Cal.). The State ofArizona was oneofthe35 States that failed to submit a revised SIPto EPA.

The EPA and theplaintiffs negotiated

a settlement agreement for the remaining States which the court approved by orderon April 20, 1984. For

more information on details ofthe provisions ofthe settlement, including a schedule ofactions byEPA, seeEPA's announcement ofthe agreement at49FR 20647 (May 16, 1984).
B.SettlementAgreement

To remedy the States' failure to submit the necessary SIP revisions during thetime specified by the regulations, the settlement agreement replaced the original regulatory deadlines forvisibility SIP provisions with a rulemaking schedule agreedtoby theparties and approved bythe court. This schedule required EPA to review theexisting SIP'sto determine any deficiencies, allow the States to cure thosedeficiencies, and to promulgate FIP's on a specified schedule for those States thatstill did not submit visibility SIPrevisions to EPA. Specifically, the first part ofthe agreement required EPA to promulgate FIP'swhich cover the monitoring and NSR provisions of40 CFR 51.305 and 51.307. The EPA promulgated its monitoring strategy for 2.3 States and its NSR provisions for21 States at 50FR 28544 (July 12,1985), 51 FR 5504 (February 1,1986), and 51 FR 22937 (June1986). In separate notices, EPA approved the SP's ofthe other States with respect to monitoring and NSR.

The secondpart ofthe settlement agreement required EPA to determine the adequacy ofthe SIP's to meet the remaining provisions ofthe visibility regulations and gave the States until December 1986to submit additional

measures that would avoid the needfor

a FIP. These provisions are the general plan provisions, includingBART and other implementation control strategies (§51.302), integral vista protection (§51.302-307), and long-term strategies

'The StateofAlaska hadsubmittedaSIPwhich

was approvedon July 5,193 at48 FR30623. 

### (§51.306). 

### The settlement agreement required EPA to promulgate FIPsto remedy and deficiencies on a specified schedule.

Pursuant to 40CFR 51.302(c)(1), on November 14,1985, the Department of the Interior (DO) certified the existence ofvisibility impairment in all Class I

areas withinitsjurisdiction in the lower 48 States.

On January 23,1986, EPA determined that the SIP'sof32 States (including Arizona) were deficient with respect to theremaining visibility provisions (51 FR 3046) and offered the States an opportunity to submit corrective SIP revisions. Thereafter, EPA and the plaintiffsnegotiated revisions to the settlement agreement which extended thedeadlines forState action or,ifthe Statesfailed to respond, Federal action proposing FTP's toremedy these deficiencies. The court approved these revisions byIts order ofSeptember 9, 1986.4



### On March 24, 1988, the DOI sent letters to EPAwhich supplemented its earlier certification ofvisibility impairment. Theletter addressed the Grand Canyon andidentified the NGS, a coal-fired power plant located near Page, Arizona, as a probable source of impairment in this Class Iarea. A copy ofthis lettermay be found in DocketA89-02.



### The affected States failed to submit visibility SIP revisions in response tothe notice ofdeficiency. Consequently, in accordance with the revised settlement agreement, on March 12,1987 (52 FR 

### 7802), EPAproposed to disapprove the SIP's of32 States, including Arizona, for failing to meet theremaining provisions ofthe visibility regulations, including general plan requirements (whichin turn includes BART and other control strategies (§51.302) andlong-term strategies 

### § 51.306)). Also in accordance 

### with the agreement, on November 24, 1987 (52FR 45132), EPA tookfinal action 

### disapproving the affected SIP's, again including Arizona. TheEPA promulgated, as FIPmeasures under section 110(c), general plan 

### requirements and long-term strategies forthese States.The EPA also determined that BARTwasunnecessary in 28 Statesbecause it could not reasonably attribute anypart ofthe impairment to specific sources. In addition,under the revised agreement, EPAdeferred until August 31, 1988

### a decision regarding the need forBART or other control measures in theFIP's for the States ofArizona, Maine,

4A copy ofthe settlementagreement and revisionsis available indocket A-85--26 atthe addressgiven atthebeginning ofthisnotice. 

### Minnesota, and Utah to address certifiedvisibility impairments in seven ClassIareas in these Stateswhich potentially could be reasonably attributed to a specific source pending acquisition and evaluation ofadditional monitoring information regarding the potential sources ofimpairment. The EPA required additional information to determine whether any part ofthe impairment in any ofthese ClassIareas is "reasonably attributable" to an existing stationary facility, and to enable a BART analysis forany source
so identified as causing or contributing to visibility impairment (40 CFR 51.302(c)(4)(i)).

Because EPArequired Information which wasforthcoming butnot available in timeto meet theAugust 31, 1988 deadline, theAgency sought and received a second extension, until August 31,1989,ofthe deadline for issuing a rulemaking proposal regarding the need for BARTorother control

measures toremedy visibility impairments in three ofthe remaining Class I areas (MoosehornWilderness, Grand Canyon National Park, and Canyonlands National Park).With regard to the impairment in the Grand Canyon,EPA delayed action in orderto allow theNational Park Service (NPS time to analyze the data from a 1987 winter visibility attribution study, termed the Winter Haze Intensive Tracer Experiment (WIHTEX), conducted in the Colorado Plateau where this Class Iarea is located.In the meantime, on May19,1989 (54FR 21904), in accordance with the second revision to the settlement agreement, EPApromulgated decisions concerning certified visibility impairments in four of the seven Class Iareas. Based on monitoring conducted in these areas, EPAfound that nopart ofthe visibility impairments were reasonably attributable to any specific source. Therefore, EPAdetermined thatit was not necessary at that timeto revise the FIP's for the StatesofMaine, Minnesota, and Arizona to include BART orother control strategies to remedy impairments in Roosevelt Campobello International Park (Canada),Voyageurs National Park (Minnesota), Saguaro Wilderness (Arizona), and Petrified Forest National Park (Arizona).

InApril 1989,EPA received a draft report onWHITEX from the NPS. Because ofthe delay in receiving this report,EPA believed that it lacked sufficient time to complete all actions in determining whether impairment in the Grand Canyon was reasonably attributable to a specific soum-e, conduct

a BARTanalysis, and Issue a proposal 5175

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## / Proposed Rules

regarding BART by the August 31, 1989 deadline. Accordingly, EPA and EDF filed ajoint motion to revise the settlement agreement for a third time, which was approved by order of the

court dated July 6, 1989. Under this revision, there was no change in the deadlines for proposed action regarding Canyonlands National Park or Moosehorn Wilderness. As to the Grand Canyon, the third revision to the settlement agreement divided EPA's duty into two parts. The EPA would proceed, on a preliminary basis, to issue

a finding on reasonably attributable impairment by the August 31, 1989 deadline. However, ifEPA did provisionally identify a specific source ofimpairment, it would solicit comments

on that finding and would have additional time to conduct a BART analysis. The EPAwas-to issue a rulemaking proposal on the need for BART by February 1, 1990 unless, in
response to comments, EPA rejected its proposed identification and instead determined thatBART was unnecessary.

In accordance with the third revision
to the settlement agreement, EPA published anotice ofproposed rulemaking onSeptember 5, 1989 (54 FR 36948). Regarding Moosehorn Wilderness, EPA identified a source of the certified impairment, but proposed that BART was unnecessary at this time because the impairment would be adequately remedied by the retirement of certain existing emission units and the addition ofpollution controls on other unitspursuant to a permit issued under the Act's prevention ofsignificant deterioration provisions. As to Canyonlands National Park,EPA could
not reasonably attribute the certified impairment to a specific source and so proposed that BART was unnecessary. On June 13, 1990 (55 FR 24060), EPA promulgated its decisions that BART at that time was not necessary to address impairment in either the Moosehorn Wilderness orthe Canyonlands National Park.

Regarding the Grand Canyon, EPA preliminarily attributed a significant portion ofwintertime visibility impairment to emissions from the NGS. TheEPA reviewed the draft NPS report

on WHITEX 5and concurred with the findings of the NPS that NGS, located approximately 20 kilometers from the boundary ofthe Grand Canyon, is a substantial contributor to the wintertime visibility impairment. The EPA solicited
comments on the merits ofits

Malm, at al., "The National Park Service Report

on WHITEX Draft Final Report" (April 7,1989). preliminary attribution finding. In addition, EPA discussed certain legal and regulatory issues relating to the BART process, as itmight affect NGS, that had previously been raised by the SaltRiver Project (SRP) and Alabama Power Company, et al., and solicited

comments on those issues.

In commenting on the September 5, 1989notice, SRP and others renewed their earlier arguments on legal and regulatory issues. They also made new arguments alleging that they could not
comment adequately on EPA's preliminary attribution finding because the NPS draft WHITEX report on which it was based was subject to change. All ofthe issues raised by SRP are addressed in detail in a later section of this notice. The EPA notices, however, that comment regarding the adequacy of the September 5, 1989 notice and the draft WHITEX report have been rendered moot by the fact that the NPS has now issued a final report on WHITEX 6and by today's notice. This notice contains the complete statement ofbasis and purpose for a regulatory proposal required under section 307(d)(3) ofthe Act, and reopens the
comment period on the issue of reasonably attributable impairment, as well as providing an opportunity to comment on all other issues relevant to this rulemaking.

On August 1,1989, the SRP, etal., and Alabama Power Company, etal., intervenors inEDFv.Reilly,moved the
court to modify the rulemaking schedule under the settlement agreement. In this motion, the intervenors challenged the court'sjurisdiction to order EPA to conduct anyrulemaking that might result in the installation ofBART at NGS. The intervenors laterfiled a separate motion requesting a 1-year delay in the rulemaking schedule. By order dated November 22, 1989, the
court denied the intervenors' motion challenging the court's jurisdiction. By order dated January 9, 1990, the court granted the intervenors' motion to extend the deadlines. This order set February 1, 1991 as the new deadline for EPA to propose whether or not to require BART emission limits for the NGS to remedy winter visibility impairment. The order also extended the deadline for final action on any proposal regarding BART until October 1991 (6 months after the close ofthe comment period).7

6Maim, at al., "The National Park Service Report

onWHITEX Final Report" (December 4. 1989).

7 EDF has appealed the extension ofrulemaking deadlines in this case EDFv. Reilly,No. 90-15264 (9th Cir.).That appeal is pending. The National Research Council of the National Academy ofSciences (NAS) has reviewed the scientific methods used in the'WHITEX report and has issued a report. The qualitative

assessment in the NAS report entitled "Haze in the Grand Canyon; An Evaluation ofthe Winter Haze Intensive Tracer Experiment" (October 1990) supports EPA's finding that, on some days, NGS contributes significantly to haze in the Grand Canyon. The NAS report has been placed in the rulemaking docket.8 The report also finds that the data base and data analyses techniques in WHITEX alone

were not sufficient to ascertain the quantitative NGS contribution to haze at any given time. The EPA solicits
comment on both the relevance ofthe report to today's action and its contents.

Another study effort has been undertaken by SRP. This study is intended to measure the degree of contribution by the NGS to visibility impairment in the Grand Canyon during the 1989L1990 winter season.The EPA has received some preliminary results from this study and has placed them in Docket A-89-02A. However, EPAhas
not yetreceived final results ofor a report on the study. If the final study results and -reportare submitted during the comment period ofthis action, and if EPA's review ofthe report indicates that the latest information would materially affect the proposed attribution decision which is the underlying basis forthis rulemaking (including the emission limitations proposed herein), the EPA will reopen the public comment period
to consider such additional information.

C.NavajoGeneratingStation

The NGS is a 2250 MW coal-fired
power plant located near Page, Arizona. approximately 20 kilometers from the northern boundary ofthe Grand Canyon. The NGS is a baseload generating station consisting of three 750 MW units which became operational between 1974 and 1976. The NGS is jointly owned by the U.S. Bureau of Reclamation, the SRP, the Los Angeles Department ofWater and Power, the Arizona Public Service Company (APS). the Nevada Power Company, and the Tucson Gas and Electric Company. Existing pollution control equipment at NGS include electrostatic precipitators forparticulate matter (PM) removal and specific burner design for nitrogen oxides (NO.) control.

£ Additional copies ofthis report are available from the National Academy Press.2101 Constitution Avenue NW., Washington. DC 20418." 

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Potential adverse impacts to the environment, especially to air quality, have been ofconcern to citizens and State and Federal agencies since construction of theplant was first announced in the late 1960's. In April of 1970, the Secretary ofthe Interior expressed his concerns over potential environmental impacts ofthe NGS in a memorandum to the Assistant Secretary for Water and Power Development. Secretary Walter Hickel stated, "As you know, the Department isconcerned with and is an outspoken advocate for protection and enhancement of the quality ofour Nation's natural environment. The Grand Canyon area of the Colorado Riveris ofparticular

concern to me. We must not allow
anyone to pollute the environment there, and it would be unthinkable forus to pollute it ourselves." 9 On February 3, 1971, in a letter toEPA, the Arizona Division ofAir Pollution Control expressed its concern about the impact ofthe power plant on visibility in the region and requested EPAto provide information on the impact ofthe NGS emissions on visibility. 1 0

Inresponse to these and other
concerns, NGS issued a strong policy
statement indicating that its NGS participants were committed to ensuring environmental protection. Furthermore, the NGS stated, "the plantwill be designed so that additional control equipment, including devices for removal ofoxides ofsulfur, can be addedwhen developed." 11 In the final environmental statement for theNavajo Project, NGS participants stated, "the participants have committed themselves
to installing sulfur dioxide (SO 2 ) removal systems on all three units at the Navajo Generating Station * * *. It

is planned that an SO2 removal system will be installed and operative before * * * May 1975." 12 Although
mostcommitments made by NGS for installing SOs removal systems centered around complying with State orFederal ambient air quality standards, NGS acknowledged in the final environmental impact statement that operation ofthe plant could result in adverse visibility impacts. Furthermore, the NGSparticipants indicated that a goal ofthe participants in the Navajo

9Memorandum from Walter 1. Hickel, Secretary ofthe Interior,to the Assistant Secretary ofWater and Power Development. April 3.1970.

10Letter from Arizona Division ofAir Pollution Control to EPA. February 3.1971.

11Policy statement bythe participants inthe
NGS, 1971.

12 Final environmental statement for the Navajo Project. page 31,February 4,1972. Project was to prevent such adverse impacts.18

In summary, all ofthe above citations indicate that the protection ofvisibility in the Colorado River Basin was of

concern priorto construction ofthe NGS. Moreover, statements made by the NGS participants indicate a strong commitment toprotecting the environment (including visibility). All of the above historical documents, including the draft and final environmental statements for the NGS, have been placed in Docket A-89-02. Today's Action

The September 5, 1989 preliminary finding that a significant portion of wintertime impairment in the Grand Canyon was reasonably attributable to NGS was not based on any single analytical technique in the WHITEX report, but rather on the collection of techniques performed by the NPS using WHITEX and other data. All ofthe techniques used by the NPS support the conclusion that for most days which
tracer data are available, NGS is a significant contributor to visibility impairment in the Grand Canyon during the winter months. The EPA has reviewed the NPS December 4, 1989 final report on WHITEX and the NAS evaluation ofthat report and finds no basis to reverse the Agency's preliminary finding that a significant portion ofthe visibility impairment in the Grand Canyon isreasonably attributable to NGS. The EPA solicits
comments on the merits oftoday's proposed reasonable attribution finding. The EPAhas reviewed comments by SRP and by others on the September 5, 1989 notice criticizing the draft WHITEX report and EPA's reliance on it in making a preliminary reasonable attribution finding. TheEPA is seeking additional comment on this and related studies, but is not persuaded by these
comments to reverse its preliminary finding at this juncture.The EPA will address in detail technical issues regarding the attribution question following receipt of comments on the final WHITEX report and NAS evaluation and will make a final attribution finding in conjunction with its final action on today's regulatory proposal.

In June of1989, EPA began to gather preliminary information on the NGS that could be used in a BART analysis. An EPA contractor visited the power plant in order to compile site-specific data. Following publication ofthe September 5, 1989 notice preliminarily attributing

Is

Ibid.pg. 59. impairment In the Grand Canyon to NGS, a full-scale BART analysis was initiated. In accordance with the BART Guidelines (EPA-450/3--80-009b) 14 and 40 CFR 51.301(c), the analysis included consideration ofthe following: The costs of compliance, the energy and nonair quality environmental impacts, any existing pollution control technology in

use at the facility, the remaining useful life ofthe source, and the degree of improvement in visibility anticipated to result from application of controls. A
copy ofthe BART Guidelines may be found in Docket A-89-02A.

In order to evaluate its BART analysis approach, EPA considered the costbenefit analysis conducted as a part of the preliminary Regulatory Impact Analysis (RIA) (as required by Executive Order 12291] for thisrule. This analysis also satisfies the requirements ofsection 317 ofthe Act regarding economic impact assessments. A more detailed discussion ofthe benefits associated with improving visibility in the Grand Canyon is found in the "Benefit Analysis" section ofthis notice.

The BART Guidelines published in 1980 stated that the level ofcontrol necessary to meet the new source performance standard (NSPS) for power plants 15 is generally available to large
power plants.1 6 However, the guidelines do allow the State (orEPA in this case)
topropose an emission limit other than NSPS ifthe limit proposed reflects a "reasonable balance ofthe various BART factors." 17 The BART Guidelines further state that, ifthe State (orEPA)
set a BART limit equivalent to the NSPS level ofcontrol, no detailed analysis of the BART factors would be required.' 8 In lightof the Clean Air Act Amendments of 1990, EPA believes that the BART Guidelines are outdated in certain respects, and should berevised.

The 1990 Amendments embody certain statutory changes thatrepresent

a general congressional policyjudgment
to move away from rigid control technology requirements and towards

an emphasis on airpollution control strategies that reflect flexibility and market-based incentives. In particular, section 403 ofthe Amendments revised section 111(a)(1) ofthe Act to repeal the percent reduction requirements under the NSPS program. Also, title IV ofthe

"4

U.S. EPA "Guidelines for Determining Best Available Retrofit Technology Analysis forCoalFired Power Plants and OtherExisting Stationary Facilities," November 1980.

"See 40CFR part60subpart Da.

B DARTGuidelines at 1.
17Id.at O. 18ld.at 20-21. 

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amendments added an acid deposition control program, the essence ofwhich is the use ofmarket-based incentives (through freely tradable allowances under section 403 ofthe revised Act) to achieve the greatest reductions in SO emissions at the least cost.

In light ofthese developments, and considering the statutory mandate in section 169A to consider the various ,BART factors ofcost, energy effects and the degree ofvisibility improvement. EPA believes it would be inappropriate to base BART analyses on NSPS-level controls. Inthis case, EPA has conducted a thorough analysis of the statutory BART factors that is consistent with the existing Guidelines, rather than base its analysis on NSPS controls. The Agency believes that all future BART analyses should also carefully balance the statutory BART factors. Accordingly, by this notice EPA solicits comment on theBART Guidelines, and specifically

on whether theBART Guidelines should be amended concurrently with this BART rulemaking. Based on those comments, EPA will decide at the time offinal action on today's BART proposal for NGS whether to amend the Guidelines.

In addition, EPAnotes that the value ofmarketable allowances under section 403 ofthe Clean Air Act as amended by the Clean Air ActAmendments of1990 willbe made available to SRP should BART be installed.The EPA has factored the value ofthese allowances intoits calculations ofthe cost ofBART. The Agency believes that this is consistent with the estimation ofBART costs under the BART Guidelines. However, EPA also solicits comments

on whether the BART Guidelines should be revised as part ofthisrulemaking in orderto consider the value of marketable allowances available under section 403 ofthe Act.

In today's action, EPAproposes to revise the FIPforArizona to include this emission limitrepresenting BART to address the visibility impairment .observed in the Grand Canyon. Because ofthe uncertainty in determining the improvement in visibility expected as a result ofreducing emissions at theNGS, EPA Is considering and solicits comment

on four options forBART at NGS:

1.A continuous SO2

### emission limitation of0.30 pounds per million British Thermal Units (lbs/MMBtu). Compliance would be determined on a 30 day rolling average and would be phased in between 1995 and 1999.



### 2. A continuous SO2

### emission limitation of0.50 lbs/MMBtu. Compliance would be determined on a 30 day rolling average and would be phased in between 1995 and 1999.

- 3. A continuous SO emission limitation of0.10 lbs/MMBtu. Compliance would be determined on a 30 day rolling average and would be phased in between 1995 and 1999.

4. SRP would test alternating control technologies and ifone ofthe technology met a minimum removal efficiency at a set cost the NGS would install that technology and operate itin the winter time. Ifnone ofthe technologies met the test criteria, NGS would reduce it emission by 70 percent (0.30 lbs/MMBtu emission limit) measured on an annual basis by the
year 2000.

More details on these options are provided below. In addition, EPA solicits comments on whether another emission limitation may be more appropriate.

The EPA is proposing this first option of0.30 lbs/MMBtu emission limit. That option includes a 30 day rolling average but EPAis requesting comment on whether a different averaging period
may be more appropriate.

TheEPA also invites comments on the legal and regulatory issues raised by SRP and others. These issues are identified and discussed in a later section.

A public hearing on this action will be

on Monday, March 18,1991 at 1 p.m. in' the Maricopa County Auditorium, 201 West Jefferson, Phoenix, Arizona.

A. DiscussionofImpairment

The DOI has documented the

occurrence of visibility impairment at the Grand Canyon during winter (November-March) inversion conditions (see discussion at 52 FR 7802). This Park is a mandatory Class I Federal area located in the Colorado River area ofthe Colorado Plateau. The visibility impairment identified in thisNational Park during the winter months has been described as a haze "with a bright white layer and a distinct upper edge and it occasionally includes one or more perceptible layers." 19

The WHITEX study, a 6-week study conducted in January and February 1987 in the Colorado River area, was designated to evaluate the ability ofa variety ofreceptor modeling approaches to attribute all or a meaningful portion ofthe visibility impairment in several Class I areas. The NGS was chosen as the test candidate because (1) it had documented build up ofhaze layers around the facility, (2) it was the largest uncontrolled power plant in the Southwest, (3) it is located a few miles

19 Maim. et at.. "TheNational ParkService Report on WHITEX Final Report." December 4. 1989,pg.4. 

### from the Grand Canyon and near several other National Parks, and (4) it is a large isolated source. TheWHITEX study was a cooperative effort between several utility groups including SRP-the operators ofNGS-and several government agencies including NPS.The WHITEX study employed several attribution methodologies including the

use of a unique tracer injected into the NGS stack to track thepower plant's plume. Ameteorological analysis was conducted to document the wind flow patterns and stagnation events occurring during the winter months.

The study area consisted ofthree major and nine surrounding monitoring sites.Major monitoring sites were located in the Grand Canyon (at Hopi Point), Canyonlands National Park, and Page, Arizona (near the Glen Canyon Dam). The surrounding sites were located in potential transport pathways in the study area.Extensive air quality monitoring was conducted at these sites to evaluate NGS' contribution to visibility impairment in the area.

The NPS calculated a light extinction budget for each ofthe thred major sites based on optical and aerosol measurements taken simultaneously at each site.The light extinction budgets express the relative contribution to light extinction by various aerosol constituents (e.g., sulfates or organics)

or the type ofextinction observed (e.g.. scattering or absorption). Light extinction, a standard measure of visibility impairment, is the combined effect oflight scattering and absorption. The NPS found that scattering dueto fine particle sulfates accounted forthe largest share of anthropogenic visibility impairment during theWHITEX study period in the Grand Canyon.

The NPS then attributed the extinction (due to fine particle sulfates) tospecific source(s) using various receptor modeling techniques. Both statistical methods and a deterministic model were used to estimate the relative contributions ofsources within the study area to visibility impairment observed during the 6-week study. Other less quantitative techniques were also used to attribute theimpairment observed to specific sources. An emissions analysis was conducted along with a meteorological analysis and and analysis ofthe spatial patterns and temporal trends in ambient sulfate concentrations..

The NPS report onWHITEX concludes that NGS was the largest single contributor to visibility impairment in the Grand Canyon during the days forwhich tracer data were available. The analytical techniques 5178

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conducted by the NPS indicate that .undercertain meteorological conditions which arecommon in the area during the winter months, large quantities of
S02 and sulfate from NGS are 

### transported intothe Grand Canyon. The
tracer analysis included measurement at Hopi Point (onthe rim ofthe Grand Canyon) oftheunique tracer,deuterated methane, which was injected into the NGS stack.An analysis ofsynoptic meteorology showed that the high sulfate episodes observed during the WHITEX study period were typical results oftransport and transformation ofpollutants during the wintertime.

The NPS analyzed extensively the data collected at Hopi Point duringthe three major sulfate episodes. All ofthe analytical techniques used by NPS suggest thatNGS is a significant contributor tovisibility impairment during the winter months in the Grand Canyon. The NPS data indicate that, for days tracer data are available, NGS contributes approximately 40percent on the average to the observed wintertime visibility impairment and approximately 60-70 percent during theworst visibility impairment episodes. During some episodes, theNPS analysis identified
copper smelters located in southern Arizona and Mexico as probable major contributors to visibility impairment. It is important to note that subsequent to the 1987 studytimeframe, these sources have either been controlled to reduce emissions orshut down.

Using the draft NPS report on WHITEX as a basis, EPA, on September 5, 1989, proposed to find that NGS may reasonably be anticipated to cause or contribute to visibility impairment in the Grand Canyon during the winter months. Acopy ofthe final report has beenplaced in Docket A-89-02. As required by section 169A of theAct, EPAconducted a BART analysis to determine ifnew emission limits were required to address this impairment.The results oftheBART analysis are discussed laterin thisnotice.

National Academy of Sciences Review ofWHITEX



### In early 1990, the National Research Council ofthe NAS established on the Committee on Haze inthe National Parks and Wilderness Areas to address issues related to visibility degradation in these protected areas.The Committee

was asked by the DOIto consider the relative importance ofhuman-derived and natural emissions that contribute to visibility reduction in these locations and to evaluate possible source-control approaches. As part ofits charge, the Committee was asked to evaluate the WHITEX report and its conclusion that the NGS contributed to wintertime visibility impairment In the Grand Canyon. The Committee met at the Grand Canyon fromMarch 28-31, 1990. The Committee issued itsreport on WHITEX on October 11, 1990, a copy of which is in the docket. On the basis of the data presented to theCommittee in theNPS-WHITEX report, the Committee concluded that, at some times during the study periodNGS contributed significantly to haze in theGrand Canyon. This finding supports EPA's proposed attribution decision. However, the Committee also concluded that WHITEX did not quantitatively determine the fraction ofsulfate aerosol and resultant haze in the Grand Canyon that is attributable to NGS. The Committee cited problems with the tracer massbalance regression (TMBR) and differential massbalance (DMB) regression calculations which, in the Committee'sjudgment, prevent the quantification ofNGS' contribution to haze due to sulfate at the Grand Canyon. The key deficiencies cited for TMBR were lack oftracers for other thanNGS sources ofsulfur,insufficient investigation ofthe covariance between NGS emissions and other sources, and limited evaluation ofthe conversion rate ofSO2 to sulfate. ForDMB calculations, 

### theCommittee cited the lack ofdata belowthe rimofthe canyon and that background measurements were not adequately incorporated into the data analyses, as well as the limited evaluation ofthe conversion rate.

For illustrative purposes, the Committee then used the WHITEX data In a simple technique to estimate the ranges ofpossible impacts from NGS. The actual impact ofNGS on haze depends on a variety offactors including the rate ofconversion ofSO 2 

### to sulfate. TheCommittee concluded thatifNGS emissions were controlled, thenwintertime haze at the Grand Canyonwould most likely be reduced, butnot eliminated.

The NPS issued a technical response document to the NAS committee report

on October 30, 1990.That document 

### responds to the keypoints ofthe NAS report.The keyissues ofassessment of background sulfate measurements and analysis, measurements ofsulfate below the rim ofthe canyon, and rates 'of conversion were addressed. TheNPS response has beenplaced in Docket A89-02A. The NPS points out that the NAS review did not fully consider supplemental techniques such as empirical orthogonal function analysis toTMBR and DMB which were in the WHITEX report.These supplemental analysesprovided byNPS seek to address the issue of other sulfur sources and support the reasonableness ofthe attribution range derived in WHITEX.

1988Visibility Follow-Up Study

The NPS has submitted a report to EPA presenting the preliminary findings ofa follow-up visibility study conducted during the winter of1988 (January 27- February 16) atIndian Gardens in the Grand Canyon. Visual examination of photographic data collected during the

WHITEX study showed thathaze built
up within the canyon and only impacted the monitoring site (Indian Gardens) at Hopi Point after the mixing height had reached above the canyon rim. This prompted NPS researchers to locate a monitoring site for the 1988 study within the canyon to assess the concentration and estimate the origin ofthe aerosols within the canyon. The Indian Gardens site was located some4,000 feet below the rim ofthe canyon.

Preliminary results ofthe study indicate much higher sulfate concentrations within the canyon than those collected on the rim during the WHITEX study.These results also show

a strongrelationship between total sulfur and selenium concentrations, suggesting that sulfur compounds in the
canyon are a result ofemissions from coal-fired sources. The WHITEX study showed that the NGS plume was rich in selenium. Finally, an examination of meteorology and photography data collected during the 1988 study indicate transport conditions similar to those documented forthe highest WHITEX sulfate episode. The clouds are shown to roll in from the direction ofPage, Arizona, and fill the canyon with haze. The NPS is continuing its analysis of data collected during this study.

Although the study conducted by the NPS inthe winter of 1988 cannot be used to confirm the NPS analyses ofthe WHITEX data, the EPA believes that the preliminary findings of this study are consistent with those ofWHITEX and generally support its previously proposed attribution decision and range ofattribution used in the BART analysis. A copy ofthe preliminary report submitted toEPA by the NPS has been placed inDocket A-89-02A.

SRP Winter 1990Visibility Study

In the winter of1989-1990, SRP conducted its own monitoring study including release oftracer from NGS. Preliminary results ofthat study and subsequent data analysis were sent to EPA and NPS in September and December, 1990. Initial data analysis by
SRPindicates thatthe overall. contribution of NGS to haze at the, 

### Federal Register I Vol. 56, No. 27 / Friday, February 8, 1991 / Proposed Rules 5179

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## .JFriday, February & 1991 

## 1 ProDosed Rules

Grand Canyon duringthe study period

was less than that computed from WHITEX data. All data and analyses received have been placed in DocketA89-02A. However, preliminary data on episodic impairment levels and seasonal average data are substantially the same
as ranges found in theWHITEX study that were used in theBART analysis. The EPA believes it is inappropriate to alter the conclusions reached in EPA's attribution finding given the preliminary and inconclusive nature ofthe SRP data. The EPA will consider all analyses and data provided during the comment period. As stated earlier, ifEPA receives the final study results and report during the comment period and ifEPA's review of the report indicates that the latest information would materially affect the proposed attribution decision, EPA will' reopen the public comment periodto consider'such additional information.
EPA'sPosition on theAbility to Determine NGS' Contribution to Visibility Impairment at the Grand Canyon

The EPA reviewed the WHITEX report, the NAS report, NPS response to the report, and the preliminary data on the SRP 1990 tracer study.Based on this review,EPA has found no reason to change its determination that visibility impairment at the Grand Canyon can be attributed to NGS. Because ofthe uncertainty in the source-impairment relationship EPA is seeking additional comment on it. But forthe purpose of thisproposal, EPA continues to believe that a relationship can be reasonably made.

B.BARTAnalysis



### TheEPA conducted a BART analysis for the NGS pursuant to theprocedures found in the BART Guidelines as required by section 169A(b) and the visibility regulations promulgated at 40 CFR 51.302(c)(4)(iii).20 Acopy ofEPA's BART analysis for NGS has been placed in Docket A-89-02A. Considering the requirements found in this document, EPA divided theBART analysis into two major parts. In the first part,EPA identified the SO emission controls that

are readily available to the source, the costs ofsuch controls, and other impacts ofinstalling and operating the controls. In the second part ofthe BART analysis, EPA attempted todefine the sourceimpairment relationship which was then used to predict theimprovements in visual air quality that can reasonably be expected to occur as a result of

20 U.S. EPA, "Draft Report on BestAvailable Retrofit Technology (BART) Analysis for the Navajo Generating Station in Page. Arizona." January 1900. installing and operating the controls defined in the control technology analysis. Because EPA was.faced with

someuncertainties in each of the parts ofthe BART analysis, EPA bounded its results by giving low and high estimates.

In addition to the key areas discussed below, EPA was also required to consider the time, frequency, and duration of the visibility impairment episodes in the Grand Canyon. This proposal focuses on impairment observed during the winter season (between November 1and March 31). Based on information from the WHITEX study and previous air quality monitoring, the visibility impairment episodes were determined to occur approximately 10 to 15 times throughout the winter months, generally lasting from 3-5 days. The NPS submitted information to EPAindicating that approximately 800,000 people visited the Grand Canyon during the winter of1989. This figure represents about 21 percent ofthe total annual visitation to the park. Documentation for visitation rates to the Grand Canyon has been placed in Docket A-89-02.

1. Control Technology Analysis

As part ofthe BART analysis, EPA investigated the costs and other impacts associated with proven SO2 removal systems at three levels different emissions limitations 0.50 lbs/MMBtu (approximately 50 percent control), 0.30 lbs/MMBtu (approximately 70 percent control), and 0.10 lbs/MMBtu (approximately 90 percent control). It

was not the intent ofthe Agency to design an SO2 control system for the NGS, but rather to evaluate the potential .impacts to NGS ofS02 control systems that have been used successfully in prior retrofit cases. Both wet and dry scrubbing technologies were evaluated in the control technology analysis. The EPA solicits comments on other available technologies which can reduce SO2 emissions at NGS to achieve the proposed or alternative limits and which may require less capital investment and/or operating expenses than those technologies evaluated in the BART analysis.

The EPA used the Integrated Air Pollution Control System (IAPCS) cost model to predict the capital and operating cost estimates for the control systems analyzed.' 1 This model was developed by EPA for the National Acid Precipitation Assessment Program and has been used to estimate SO2 and NO. retrofit control costs for 200 power

2 Integrated Air Pollution Control System Costing Program. Version 3.0, copyrightPEI and Associates. Inc..1989. plants. The case-specific input parameters were determined through documents obtained from the NGS

- . information collected during the site visit by the EPA contractor and other government records. As mentioned previously, lower and upperbound limits were generated for each control option. The results from IAPCS indicated thatwet flue gas desulfurization (FGD) achieving a 0.3 lbs/MMBtu emission limit for all three units is estimated to have total capital
cost requirements ofbetween $245.9 million and $402 million with total levelized annual costs (including amortized capital, interest, operating, and maintenance costs) estimated to be between $91.9 million and $128.3 million. 22The levelized annual costs for 0.3 lbs/MMBtu wet FGD are less than those for lime spray drying or dry sorbent injection at the same emission
rate. The wet FGD control option to meet a 0.10 lbs/MMBtu emission limitation is estimated to require a total capital investment ofbetween $275.7 million and$453.2 million for all three units with total levelized annual costs estimated to be between $103.5 million and $145.2 million. A 0.5 lbs/MMBtu emission limitation met by a wet FGD control option is estimated to require a total capital investment ofbetween $213.3 million and $357.0 million for all three units with total levelized annual
costs estimated to be between $79.5 million and $112.2 million.

Using the costs generated by IAPCS, and the methodology originally used in the RIA for NGS, EPA estimated the increases in the average SRP's and Nevada Power Company's residential customers' electric utility bills ifwet FGD were selected to decrease NGS SO emissions to 0.30 lbs/MMBtu. This increase is expected to be no greater than2.8 percent (about $2.30 per month) forthe SRP customer and no greater than about a 3.9 percent increase (again, approximately $2.30 per month) for the Nevada Power Company customer. Because SRP and Nevada Power Company receive a higher percentage of their total system power from NGS than do other co-owners ofNGS and have a lower average cost per kilowatt hour, these estimated 2.8 to3.9 percent increases are expected to be the maximum percentage increase in power costs experienced by residential customers of NGS. These price increases would be lower for the 0.50 lbs/MMBtu , control option. It is important to note that these estimates are based upon



### 22 All dollaramounts herein are measured in 1988 dollars. 11I I I 

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increasing consumer costs by the percentage increase cost ofproducing the electricity. They do not consider that part ofthe consumer rates which include transmission costs; considering those
costs could dampen the effect on the

consumer. The actual increase to the average SRP orNevada Power Company residential customer isexpected to be somewhat less since the transmission
costs are not affected by the BART requirements.

Other persons potentially affected by

an increase in NGSpower are customers ofthe Central Arizona Project (CAP). The CAP is an organization established by the U.S. Bureau ofReclamation to provide government-subsidized Irrigation water to south central Arizona farmers. The CAP relies heavily on electricity from the NGS to pump and provide this water. It was estimated that ifwet FGD were selected to decrease NGS SO2 emissions to 0.30 lbs/MMBtu, the cost ofwater to users would increase approximately $10per acre foot

orabout 3 cents per 1,000 gallons. This increase in irrigation costs could raise the farmers' total variable costs by 2 percent to 4percent per year. However, If,as expected, the CAPphases down its obligation to supplying water to the farmers, the increase in total variable
costs would only be approximately 2 percent per year. Again, the cost increases would be lower for the 0.50 lbs/MMBtu control option. A more detailed discussion ofthese impacts
may befound in the RIA and in factual memorandum 23 placed in Docket A-89- 02A.

As a plausibility check for the costs generated by IAPCS, EPA requested information from the APS regarding the
costs forFGD retrofit of units 4 and 5 at the Four Comers Power Plant located in Farmington, NewMexico. These units

are similar to NGS in many respects Including capacity and design, the burning oflow sulfur coal, and the
remote location ofthe plant. Information supplied by APS indicates that the capital investment forthe wet FGD removal system (averaging 72 percent reduction in SO2 emissions) at Four Comers Power Plant was $119.8 million per unit. The IAPCS model generated
costs for control atNGS ranging between $82-$134 per unit forthe 0.30 lbs/MMBtu wet FGD control option. The EPA, therefore, concludes that the IAPCS model estimates are reasonable. A copy ofthe letter from APS has been placed inDocket A-89-02A.

33 Memorandum fromGwen Jacobs to David Stonefield dated January 30,1991. Title IV (section 403) ofthe Clean Air Act Amendments of1990 establishes a system of marketable sulfur emission allowances to help achieve the goal of reducing acid deposition. This provision does not waive any BARTrequirements for NGS. Nor does it require more controls than NGS currently has. However, the control cost incident with BART may be affected in part by NGS selling its excess emission reduction allowances. While the allowance system begins in 1995, western sulfur sources such as NGS are not included until 2000. The annual sulfur emission reductions at NGS due to the current proposed regulation could be offered for sale by NGS. The EPA estimates 24 the market value ofsulfur reduction credits will be $430/ton in 2000, increasing to $590/ton in 2010.At an emission limit of0.30 lbs/ MMBtu, estimated total revenue for emission credits are $21.4 million/year in 2000, Increasing to $29.4 million/year in 2010. Sale ofemission credits would lower the estimated cost impacts on NGS during this period by 17 to 32 percent. The analysis ofthe acid deposition credit market, and analysis ofthe effect on NGS, have been placed inDocket A--89-02A.

In accordance with the procedures found in the BART Guidelines, the nonair quality environmental impacts of compliance were investigated. Impacts from increased water usage to operate SO2 control systems, increased waste disposal, and effects ofsludge from the 

### SO2 control system onground or surface
waters were examined in the BART analysis. Results from the BART analysis indicate that adequate space is available to dispose ofadditional
wastes that would be generated by a control system.Also, the results show that the environmental effects ofsludge disposal from the control system should present no increased threat to the environment beyond those currently being posed through fly-ash disposal. Finally, although S02 controls would require an increase in water usage, NGS is only utilizing approximately 68 percent ofits water allotment. The remainder ofits allotment should be adequate to operate a wet FGD or dry control system. In addition, water requirements for SO controls can be reduced ifas indicated in the environmental statement previously conducted forthe NGS, the 'cooling
tower blowdown water is utilized in the SO2 control system.

2. Source-Impairment Relationship

24

ICF Resources. Inc., 1990, "Comparison ofthe Economic Impacts ofthe Acid Rain Program of Senate Bill (S. 1630) and the House Bill (H.R. 3030). 

### One ofthe more complicated tasks in theBART analysis was defining the relationship between the SO2 emissions 

### at NGS and the visibility impairing sulfate (S04) in the Grand Canyon. This 

### relationship hadto be addressed in orderto estimate the degree of improvement in visibility that could be anticipated to resultfrom theuse ofthe alternative SO2 control systems.



### Because ofthe complex terrain in and around the Grand Canyon; the EPA visibility models that are often used to estimate improvements invisibility (e.g., PLUVUE II)were determined to be inadequate forthis BART analysis. Based on conversations with EPA researchers and modeling experts, 25 

### the Agency decided to define this relationship using the ratio ofSO2 emissions at NGS to SO4 in the Grand 

### Canyon attributable to NGS as found in the finalWHITEX report. Using this ratio,EPA thenapplied a linear rollback model. TheNAS' Committee on Haze in National Parks and Wildernesses used the data inWHITEX and a series of mass-balance calculations on the basis ofsimple, but reasonable assumptions, to estimate the contribution ofNGS on visibility impairment in the Grand Canyon during a haze episode. The Committee concluded that it could not confirm the WHITEX estimates because

somemeasurements needed to confirm the assumptions were notmade during WHITEX. The EPA believes that the NPS data from WHITEX and other monitoring coupled with assessment techniques that do not depend directly

on mass-balance techniques provide adequate data concerning the NGS contribution ofhaze which could be used in the BART analysis. However, the uncertainties surrounding these analyses, as pointed out by the NAS committee on haze, requires that EPA consider a broad range of sourceimpairment relationships.

An important consideration in defining the source-impairment relationship was determining whether a proportional reduction in NGS SO 2 

### emissions would result in a proportional

or less-than proportional reduction in visibility impairment in the Grand Canyon attributable to NGS. Potential nonlinearities resulting from condensation ofadditional nitrate aerosol once theNGS sulfate is controlled were investigated.

The case mentioned above addresses the nonlinearity that may exist when 

### SO 4 

### is taken out ofthe atmosphere.

25 Memorandum from Terry Clark.Atmospheric Research and Exposure Assessment Laboratory, to James Dicke, OAQPS, December18, 1989. 

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Ammonia thatwould have combined with the SO4 to form ammonium sulfate 

### would nowbe free to combine with nitric acid to form ammonium nitrate, an efficient light scatterer. By comparing the light extinction reduction resulting from S04 reduction to the net light extinction reduction resulting from the combined effects of S04 reductions and 

### nitrate increases, a nonlinearity factor

canbe developed and applied to the rollbackmodel calculations. The average nonlinearity factor forthe hours forwhich all necessary data are available from the WHITEX study is 0.10. In other words, the relationship is estimated to be 90percent linear.

Theresults ofthe rollback model (with the average nonlinearity factor applied) were used to estimate the improvements in visibility that would result from SO2

### emission limits of0.10 and 0.30 lbs/MMBtu at NGS. Because no single standard method exists for measuring improvements in visibility, theEPA employed two ofthe most widely used techniques to define the improvements in visibility expected to

occur in the Grand Canyon.

One ofthe methods used to estimate the visibility improvements in the Grand Canyon was anlayzing the changes in contrast expected to occur as aresult of reducing SO2

### emissions at NGS. The EPA believes that this method is particularly relevant because human observers use contrast tomake judgments ofhow color and atmospheric clarity changes with pollutant concentration. The contrast is defined as the percent difference between the brightness ofa scenic element and its background.

Using the information obtained during the WHITEX study and extrapolating it
to a period from November I through March 31 based on historic particle composition data (and applying the nonlinearity factor), a 0.10 lbs/MMBtu SO2 emissions rate atNGS would result 

### in a "perceptible" change in the visibility conditions (4

### percent change in contrast) approximately 65 percent of the time (100 days) during the winter
season, a "quite noticeable" change in visibility conditions (10 

### percent change in contrast) 39 percent ofthetime (58 

### days) during the winter, and a "very apparent" change invisibility conditions (20 

### percent change in contrast) 14 percent of the time (21 days) during the winter.

Similarly, ifSO 2 

### emissions are reduced to 0.30 lbs/MMBtu, the following changes in winter visibility conditions are expected: A very apparent change in visibility conditions 4.5 percent of thetime (7 

### days), a quite noticeable change in visibility conditions 28 percent ofthe time (42 days), and a perceptible change in visibility conditions 58 percent of the time (88 days).

Finally, It is estimated that during an additional 29 percent ofthe time (44 days) during the winter months, there would be a "perceptible" (or greater) improvement in visibility with an SO2 emission limit of0.10 lbs/MMBtu as compared to 0.30 lbs/MMBtu. Documentation for these numbers, including assumptions and methodology, has been placed in Docket A-89-02A.

In addition to analyzing the changes in contrast in order to describe the improvement in visibility expected to

occur as a result ofcontrolling S02 emissions at NGS, the EPA also estimated the improvements in visual
ranges expected to occur. Although this method is somewhat less desirable than analyzing contrast changes (because it is sometimes misunderstood by the layman), it is often used by scientists to

measure visibility improvements. Table
1 contains the estimated improvements in visual ranges calculated for the maximum measured light extinction day and for an average day during the WHITEX study forthe 0.10 lbs/MMBtu and 0.30 lbs/MMBtu control options using the results form the tracer massbalance regression analysis performed by the NPS using the WHITEX data. As noted above, however, the uncertainty of these analyses, as pointed out by the NAS Committe on Haze, suggests that the actual effects of such emission reductions maybe substantially different from these estimates (higher or lower).

TABLE 1.-ESTIMATES OF IMPROVEMENTS

IN VISUAL RANGES WITH SO2 CONTROL
AT NGS'

SO2 emission Maximum light Average

limit (Ibs/ extinction day WHITEX day lmBtu) change invisual change in visual range range

0.

................... Increase from Increase from baseline of baseline of 150 km to 200 km to 380 km. 229 km. 0.30

.................. increase from Increase from baseline of baseline of 150 km to 200 km to 283 km. 222 km.

In addition to the wintertime in the Grand Canyon visibility impairment described above, it is believed that the control ofSO2 emissions at NGS may result in other visibility improvements. Although not specifically addressed in this rulemaking, EPA and NPS suspect that NGS emissions may contribute to visibility impairment in the Grand Canyon during other seasons of the year. Thus, a significant decrease in SO2 emissions at NGS may improve visibility in other months as well as during the winter months. Furthermore, a decrease in SO, emissions from NGS may improve visibility in other Class Iareas in the Colorado Plateau. The EPA seeks
comment on the potential visibility impairment from NGS in other than the winter season.
C.BenefitAnalysis

As statedpreviously in this notice, EPA was not required as a part ofits BART analysis to estimate monetary benefits associated with improving visibility in the Grand Canyon. However, as a check ofreasonableness for its approach, EPA evaluated and considered the benefit analysis developed as a part ofthe RIA.

Because ofits size, unique rock formations, and sheer beauty, the Grand Canyon isconsidered by many to be one of our Nation's most prized national parks. Indeed, millions ofpeople from the United States and all over the world travel to Arizona each year to view this national treasure. Placing a quantitative value on the protection ofthe beauty of the Grand Canyon is a formidable task. However, in conjunction with the BART analysis (and as part ofthe RIA), an attempt was made to identify some of the societal benefits related to the predicted improvements in wintertime visibility at the Grand Canyon due to reductions in sulfur emissions at NGS. The following paragraphs summarize the findings ofthe benefit analysis. A more detailed discussion ofbenefits may be found in the RIA developed for this rule. A copy ofthe draft RIA has been placed in Docket A-89-02A.

A key factor is assessing the benefits ofvisibility is understanding attitudes and preferences ofindividuals. Surveys 26 ofvisitors to the Grand Canyon indicate that the vast majority (over 80 percent) view clean, clear air as very important or extremely important
to their recreational experience and indicate the viewing-related activities

are particularly important at the Grand Canyon. This research also shows that visitors are aware ofincreasing haziness and that it is strongly correlated with decreased enjoyment ofthe site and with increasing dissatisfaction with air quality. Studies at recreational sites, including the Grand Canyon, indicate that visitors would plan to, and do, reduce the length ofpark visits and time
at vista points as visibility conditions

are degraded.

26 National Park Service 1988, "Air Quality in the National Parks." Natural Resources report 88-1. 

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General citizen surveys provide further support. One survey 27 found that the vast majority ofAmericans felt there should be no air pollution that would "interfere with recreation and natural resources." Another citizen
survey 28 found that 80 percent of households would definitely agree to having their tax money spent on preserving and managing park areas,

even ifthey personally could not visit them, and another 17 percent would possibly do the same.

Several studies have attempted to

measure in dollar terms societal values for varying degrees ofvisibility protection at the Grand Canyon.29

. 30
Because visibility is not bought or sold in a conventional marketplace, researchers have used various survey approaches known as the "contingent valuation method." This research has consistently shown the public's collective willingness to pay to protect visibility at the Grand Canyon is substantial.

The benefit analysis for this rulemaking interprets and transforms the existing economic research. Uncertainties arise in thisinterpretation and transformation process. Consequently, results are reported and should be interpreted as depicting the direction, character a general magnitude ofthe willingness-to-pay estimates.The benefit estimates developed here are based on the changes in visual range estimated by EPA in table I. However, given the uncertainties surrounding these analyses (as discussed above), changes in visual range could be substantially different than the change used in developing these willingness-topay estimates. In addition, these willingness-to-pay estimates are based

on response elicited from contingent valuation studies that examined a substantial, year-round change in Grand Canyon visibility. While the analysis presented below attempted to adjust for differences between the contingent valuation studies and the specific visibility affects attributed to the Grand Canyon, there are important uncertainties with the willingness-topay estimates described below.

27 OpinionResearch Corporation 1981, "Public AttitudesToward the CleanAirAct."

' Chestnut end Rowe,198, "PreservationValues for Visibility Protection at the National Parks," draft report to the U.S. Environmental Protection Agency.

'9Schulze, Brookshie, Walther and Kelley, 1981, "The Benefits ofPreserving Visibility in the National Parklands ofthe Southwest." Vol. VIII, Methods Development forEnvironmental Control Benefit Asseument, U.S. EPA.

80Rowe andChestnut. 19&3. "Valuing Environmental Commodities: Revised," Land Economics 59. 

### The benefit analysis for a 0.30 lb/ MMBtu emission limit at NGS indicates in 1995 the average United States household would be willing to pay on the order of$1.00 to $1.90 per year per household. National total benefit estimates for 1995range from $100 to $190 million. The annual benefits are expected to increase overtime due to increasingpopulation and income.The present value (using a 10percent discountrate) of30 years ofbenefits is $1.6 to $2.3 billion. Using a 3percent discount rate,thepresent value ofthe benefits range from $4.0 to $5.5 billion.

The benefit analysis fora 0.10 lbs/ MMBtu SO emissions rate from NGS indicates in 1995 the average United Stateshousehold would be willing to pay on the order of$1.30 to $2.50 per year per household. By thismeasure, national totalbenefit estimates for 1995 range from $130 to$250 million increasing over time due to growth in population and income. Thepresent value,using a 10percent discount rate, of30years ofbenefits is $2.1 to $3.1 billion.Using a 3percent discount rate, the present value ofthe benefits range from $5.3 to $7.4 billion. The annualized 

### benefits are $220 to $330 million.The benefits for a 0.50 lbs/MMBtu S02 

### emission rate would be substantially less than those calculated for 0.30lbs/ MMBtu.

Ahousehold's willingness-to-pay for visibility improvement at theGrand Canyon arises fromthree different motivations. Across all United States households, 31 percent ofthe total willingness to pay is an optionprice, or thedesire forthe household members to be able to enjoy good visibility during theirown visitsto the Grand Canyon

now and in the future. Estimates based

on willingness-to-pay surveys (McFarland,et al, 8 1 

### Schulze, et al 82) of 

### visitorsto the Grand Canyon suggest substantially lower willingess-to-pay, however, than would be expected from the "option" value estimate used in this benefits analysis. About 38 percent is bequest value, or thedesire forother people to enjoy good visibility now and in thefuture, and about 31percent is existence value, orthe desire to protect theGrand Canyon even ifno onewere to evervisit.

In September 1990, EPAreceived a draft report ofa news benefits study on improving visibility in the Grand

3,MacFarland. K.W.Maim, andJ. Molenar.1983. "An examination ofmethodologies and Social Indicators for Assessing theValue ofVisibility." in Rowand Chestnut (Eds.) Managing AirQuality and Scenic Resources atNationalParksand Wilderness Areas Boulder,Colorado: Westview Press.

32 Schulze op. cit. Canyon. The report 33 details the methodology and results ofa pilot contingent valuation willingness-to-pay study conducted on behalf ofSRP in 1990. The draft report concludes that the benefits ofreducing sulfur emissions from the NGS are substantially lower than those in EPA's draft RIA. The EPA's preliminary assessment ofthe SRP-sponsored draft report is that this conclusion results primarily from two factors. First, the SRP-sponsored draft report predicts visual range improvements which are much lower thanEPA's estimates. Second, the SRPsponsored draft report subjectively discards willingness-to-pay data for visual range improvement. The effect of the data adjustment is to lower the

mean willingness-to-pay estimates by a factor of 20. A copy of the report was provided to EPAby SRP and has been placed inDocket A-8-.02. By today's notice, the EPA solicits comments on this new information on benefits, as well

as on the benefits analysis developed as part ofthe RIA.

D.EmissionLimitations

Taking into consideration the uncertainties in the analyses, such as the attribution calculation and social benefis estimates, EPAis soliciting
comments on four options and is proposing one ofthe options, (0.30 lbs/ MMBtu emission limit). In addition the EPA solicits comment on, and will consider, any appropriate SOz emission limitation in its final determination of BART. The EPA is particularly interested in additional information that would show more precisely the range of visibility changes expected from -changes in emissions from NGS, or better confirm the range used in the BART analysis as well as any quantitative information on the visibility improvements that could be expected in times other than winter, and in areas other than the Grand Canyon. Additional information on control alternatives and their costs as well as appropriate use ofdata on social benefit for improving visibility Is also solicited. The proposed emission limitation is based on year-round control. However, EPA solicits comments on legal and policy issues relating to the use of seasonal controls instead.For a discussion ofseasonal control, please refer to the section "Discussion of Seasonal Controls as a BART Emission

33 Development and Design ofa Contingent Value Survey forMeasuring the Public's Value for Visibility Improvements at the Grand Canyon National Park: Revised DraftReport," September 1990, DecisionFocus, Inc. 

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Limitation" elsewhere in this notice. Consistent with the similar emission limitations implemented at other facilities over thepast 10years, EPAis proposing that compliance be determined on a 30-day rolling average. Nevertheless, EPA invites comments on other options for averaging times that could be used to determine compliance. Compliance with this limitation would be determined using continuous emission monitoring systems (CEMS).

Two otherpollutants emitted by NGS, NO. and PM, are known to contribute to visibility impairment in some circumstances.3 4 

### The current emissions ofNO, and PM from NGS have not been identified as significantly contributing to the visibility impairment in the Grand Canyon. However, EPAis concerned based upon its technical judgment regarding the behavior ofthepollutants

as potential contributions to visibility impairment as a general matter, upon the amount ofthe pollutants emitted by NGS, upon the proximity ofNGS to the Grand Canyon and upon the' characteristics ofthe NGS plume shown by WHITEX and other studies, that increased emissions ofthese pollutants could result in impairment in the Grand Canyon. Although the NGS is not subject to any NO. emission limitations,
SRPhas statedthat NGS currently emits NO. at a rate of0.4to 0.5 lbs/MMBtu. Therefore, EPA is proposing an NO1 

### emission limit consistent with NGS's existing emission rate, as well as the rate at other similar plants, of0.5 lbs/ MMBtu. As with the SO2 emission limit, 

### compliance wouldbe determined using CEMS.

Particulate matter emissions for the NGS are currentlylimited in two ways. The Arizona SIPkas both an emission ratelimitation of0.06 lbs/MMBtu and an opacity limit of40percent for NGS.The SRP has stated than NGS currently emits PM at a rate of0.03 lbs/MMBtu with an opacity ofbetween 10 and 15 percent.Thus, the opacity limit of40 percent is well above the NGS existing emissions.Therefore, EPA isproposing

a 20 percent opacity limitation consistent with current NGS emissions opacityin order to preclude any visibility deterioration that would be caused by an increase inPM emissions. Compliance would also be determined using CEMS. In conjunction with the proposed BART limits for SO2 

### emissions, these emission limitations for NO, and PM should result in reasonable progress toward the national visibility goal.TheEPA solicits comments on whether these emission limitations are

34 See.e.g.. BART Guidelines at 12-13. appropriate to remedy existing impairment orto prevent future impairment.

E.EmissionLimitation Compliance. Schedule

Section 169A requires BART to be applied "as expeditiously as practicable, but inno event later than 5 years after the date ofapproval." However, the operators of NGS may be able to develop in the next few years technologies capable ofmeeting the

same stringent BART limitation proposed today at costs substantially lower than those we have assumed using currently demonstrated technologies. Given that,EPA proposes the required emission limitation to be achieved in three phases. The final BART emission limitation would need to bemet on one unit by January 1,1995:

on two units by January 1, 1997; and on all three units by January 1, 1999.This flexibility would allow the operators ample time to install, test, and evaluate innovative technologies in meeting the emission limitations.

The EPA is also considering allowing the operators the option ofaveraging the needed emission reductions across all three units during eachmilestone ofthe phase-in period.This would allow, ifthe 0.30 lbs/MMBtu emission limitation is selected as BART for example, 25 percent emission reductions at two units and 20 percent reductions at the third unit by 1995 rather than achieving the 0.30 lbs/MMBtu limit by 1995 at just one unit.This would provide greater flexibility in study and design ofnew control approaches than a strict unit-byunitrequirement. The EPA is aware that this approach will raise questions regarding regulatory intent for installation ofBART. Under this approach, BART would begin before the. 5-year requirement and controls would be installed on all three units within an average of 5years.

The EPA solicits comments on whether it is legally permissible and, in the final analysis, appropriate from a policy perspective to rely on the date of controls on the first unit or the average date ofcontrols on all units in complying -withthe timing requirements ofthe
statute. In addition, EPA solicits
comments on the averaging of the phasein across units in order to provide the maximum flexibility in evaluating alternative control technologies. Proposal From Salt River Project

On January 10, 1991, EPA received a proposal from representatives ofSRP as

an alternative to BART. The proposal addresses a broader scope ofissues. including the contribution that NGS makes to the existing regional haze problem in the desert southwest region. which includes many Class I areas including the Grand Canyon, Canyonlands, Bryce Canyon, Petrified Forest, Zion, and othernational parks and wilderness areas.The proposal has four components: (1)SRP help fund and cooperate fully with the regional haze studies that EPA isrequired to conduct under the new section 169B ofthe Act; (2) EPA would expedite establishment of the Grand Canyon Visibility Transport Commission, and SRP would cooperate with the governors of the affected States and the Commission in conduct ofits inquiry and mandated report to the Administrator on appropriate action to address regional haze; (3) SRP would undertake tests to try to demonstrate the feasibility ofseveral promising clean coal technologies that may provide much lower cost alternatives to conventional scrubbers or current dry technologies on plants fired by low sulfur western coal (Ifone of the technologies were demonstrated to achieve an agreed-upon minimum removal efficiency at an agreed-upon cost, SRP would commit to install that technology and operate it on a seasonal basis to address the alleged effect of NGS on wintertime visibility.]; and (4) SRP would agree that ifnone ofthe technologies met the test criteria, it would then install pollution control devices that would remove at least 70 percent ofthe uncontrolled SO emissions (emission limit of0.30 lbs/ MMBtu) measured on an annual basis by January 1, 2000, the year upon which the first allowances would be issued to the plant under the 1990 Amendments. A
copy of the letter containing the full explanation of this offer is in Docket A89-02A. EPA is requesting public
comment on how this proposal, legally and technically, may fulfill section 169A,

as well as the provisions ofsection 169B. With respect to this proposal, EPA has concerns about the delay in application ofcontrols so far beyond
any interpretation ofthe 5-year statutory requirement. In addition, EPA requests comment on the proposal's usefulness in addressing new legislative requirements

on EPA to conduct regional haze studies. and on the role ofcooperation with industry in addressing regional haze through the Grand.Canyon Visibility Transport Commission.
Legal and Regulatory Issues

On May 15, 1989, the SRP submitted
comments on various legal and regulatory issues pertaining to potential BART emission limits affecting NGS. In addition, SRP and Alabama Power 

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### / Proposed Rules

Company, et al., a consortium ofutility
groups (referred to collectively In this section as "SRP'), have submitted various motions to the court in EDFv. Reilly seeking to modify and delay the settlement agreement governing this rulemaking. The EPA addressed these issues and solicited comment on them in the September 5, 1989 notice. See 54 FR 36951-52. The EPA's earlier discussion is incorporated by reference as part of today's statement of basis and purpose. In comments on the September 5,1989 notice, and in further pleadings in EDF

v.Reilly,SRP and Alabama Power Company, etal.,have continued to press these issues and to raise new ones. Similar views were also presented by other commenters on the September 5, 1989 notice. By its order ofNovember 22, 1989, the court rejected all ofSRP's arguments insofar as they sought to prevent EPA from proceeding with this rulemaking pursuant to the court's jurisdiction to oversee BART rulemaking under a FIP. The effect ofthat decision is to refer SRP's arguments to the rulemaking process and,ultimately, a decision by the Court ofAppeals should SRP seek review offinal rulemaking action by EPA under section 307(b) of the Act. For the benefit ofcomments on today's proposal, these issues are identified below, and EPA has setforth again its present position on these issues. The EPA will take a final position on all ofthese issues in
response to comments on today's notice.

A. Scope ofthe CurrentVisibility Regulations

The SRP asserts that regulation of haze that cannot be attributed to a

source through visual observation, but only through analytical techniques such

as those used inWHITEX, is beyond the
scope ofEPA's current visibility regulations. The EPA disagrees with this contention. The current regulations focus on impairment due to discrete, discernible plumes attributable to a

source through visual observation, but they are not limited to the type of visibility impairment known as "plume blight." Rather, as toBART, the visibility rules regulate any impairment that is "reasonably attributable" to an existing stationary facility (see, e.g., 40 CFR 51.302(c)(4)(i)). While such "reasonably attributable" impairment
may be in the form ofa haze, this Is still distinguishable from impairment in the form of"regional haze" that is beyond the scope ofEPA's current regulations because itcannot be attributed, in whole or significant part, to a single

source or small group ofsources. B.Attribution Techniques
The SRP also claims that the visibility regulations prohibit EPA from basing a finding ofreasonable attribution on the WHITEX study, asserting that sophisticated attribution techniques are beyond the scope ofthe 1980visibility regulations. The EPA disagrees with this interpretation. While the 1990 regulations do not require the use of techniques other than visual observation, they do not prohibit them either.

The SRP also asserts that if sophisticated techniques arepermissible
at all, their use is limited to the States. The SRP points to 40 CFR 51.302(s) which defines "reasonably attributable"

as "attributable by visual observation or any other techniques the State deems appropriate." In SRP'sview, the rules on their face authorize only States and not EPA to use techniques other than visual observation to make a reaqonable attribution decision. The EPA disagrees with this view. The part 51 visibility regulations, including the definition in question, contain numerous references
to the duties of "States" in the SIP planning process for the obvious reason that those regulations' principal purpose is to set forth the requirements that SIP's
mustmeet to comply with the regulations. In this instance, however, Arizona has defaulted on its responsibility as ithas failed to submit a visibility SIP orany portion thereof despite EPA's notice ofdeficiency, and EPAhas disapproved the SIP for such failure. Consequently, EPA has an obligation under section 110(c)(1) ofthe Actto promulgate such visibility

measures as may be necessary to fulfill the requirements ofthe visibility regulations at 40 CFR 51.300, etseq.In

so doing, EPA stands in the shoes ofthe defaulting State, and all oftherights and duties that would otherwise fall to the State accrue instead to EPA.Thus, in this instance, EPA is in effect acting as a "State" and may utilize any attribution technique it deems appropriate, notjust visual observation. Moreover, there is

no inherent reason why EPA should be limited to visual observation when it
acts under section 110(c) ifa State is not

so limited in developing a SIP.Similarly, 40 CFR 51.302(c)(4)(i) provides that the "State" must identify and analyze for BART any source as to which a reasonable attribution finding is made. Nevertheless, where EPA is acting in place ofthe "State" under section 110(c), these duties, as well as all other duties of"States" under the part 51 visibility regulations, fall to EPA. In thiscase, EPA is acting in the place ofArizona. The EPAhas found that the Arizona SIP 

### is deficient for failing to meet the requirements of40 CFR 51.302, including reasonable attribution and BART requirements, and has disapproved the SIPfor that failure (51 FR 3046, 3048 (January 23, 1986); 52 FR45132, 45133). The EPAbelieves that its position represents a reasonable interpretation of the Act and its own regulations and is fully in keeping with the language, goals, and purposes oftheAct and those regulations. However,in the September 5, 1989 notice,EPA solicited comments

on whether it would be appropriate to make changes in the definitional provisions of40 CFR part 51 in order to provide additional clarification on EPA's interpretation that the Administrator, like a "State," may utilize whatever techniques he deems appropriate in making any "reasonably attributable" findings inpromulgating a plan under section 110(c) ofthe Act.By today's notice, EPA again solicits comments on thisissue. Upon the close ofthe comment period that commences today, EPA may proceed to make clarifying changes withoutfurther publicnotice.

C.Attributionof Impairmenttoa SignificantContributor

Section 169A(b)(2(A) ofthe Act,42 U.S.C. 7491(b)(2)(A), requires that emission limitationsrepresenting BART be established foran existing source which emits any air pollutant which may "reasonable be anticipated to cause
or contribute to any impairment of visibility in any [Class I] area." TheEPA regulations further refine this statutory requirement by limiting BARTto cases ofreasonably-anticipated impairment "where the impairment is 'reasonably attributable' to the source." 40 CFR 51.302(c)(4)(i). The SRPargues that a finding ofreasonable attribution cannot be made unless one source (ora small group ofsources) is the sole contributor
to visibility impairment. IN support of this view, SRP states that control ofone

source would result in significant improvement in visibility onlyifthe impairment was being caused by that

source alone, whereas ifmany sources
are contributing, all mustbe controlled to result in improved visibility.The EPA disagrees because SRP'sposition appears to contravene the legal requirement flowing from the statute and regulation that BARTbe installed whenever a source may reasonably be anticipated to either cause or "contribute" to "any impairment" in "any" Class Iarea where the impairment is "reasonably attributable" to that source. In addition, EPA preliminarily believes that SRP's position is flawed logically and assumes 

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key facts that the WHITEX data indicate areuntrue orwhich are contravened by EPA's BART analysis. Specifically, ifNGS is a significant contributor to wintertime impairment in the Grand Canyon, notwithstanding that othersources may also contribute to the impairment, it follows that the addition ofemissions controls at NGS alone may result in significant improvement in visibility.In addition, as discussed above, theWHITMX data indicate that NGS is, in fact, a significant contributor to wintertime impairment in the Grand Canyon. In its review ofWHITEX, NAS likewise refuted SRP'sreasoning when NAS concluded that ifNGS were controlled thenthe wintertime haze of -the Grand Canyon would likely be reduced. Thus,in today's notice, EPA has proposed to determine that the impairment in question may be reasonably attributable to NGS. In addition, today's notice reflects that EPA's BART analysis has concluded that control ofNGS alone is likely to result in a significant improvement in visibility. Although EPA is seeking. additional comment on these studies and is prepared to analyze any additional data that is submitted, it believes that these findings and interpretations are adequate to proceed at this time with its proposal ofBART emission limits under the present visibility regulations to remedy this impairment. The EPA specifically solicits comments on its view thatit is appropriate under thecurrent visibility rules to impose BART limits on a source which is a significant contributor to but
not the sole source ofa visibility impairment in a Class Iarea when that impairment may also be due inpart to undifferentiated regional sources. D.EPA'sPresent Authority To Conduct

aBARTRulemaking

The SRPand Alabama Power Company, et al., assert that, with respect to visibility impairment in the Grand Canyon, EPAhas no present authority to conduct a BART analysis orpropose or promulgate emissions limitations representing BARTbecause there has been no valid certification of impairment, because there has been no finding ofsubstantial inadequacy as to Grand Canyon impairments and subsequent failure by Arizona to remedy such inadequacy, and because the Administrator has not made a final reasonable attribution decision. The EPA disagrees with these assertionsbecause they seriously misread the applicable statutory and regulatory requirements.

Regarding the certification of impairment, EPA believes that theDOI letters ofNovember 14, 1985 and March 24, 1986 discussed above satisfy the certification requirements ofthe regulations because they represent the considered views ofresponsible DOI officials, and Arizona was given notice ofthem by the January 1986 notice of deficiency and March 1987proposed SIP disapproval prior to EPA's disapproval of the Arizona SIPfor failing-tosubmit remedial measures in response.

Regarding the purported need to afford Arizona another opportunity to perform its own BART analysis, there is likewise no basis for such a requirement because Arizona has clearly defaulted

on its obligations, and EPA must provide

a complete visibility plan, including

measures to remedy Grand Canyon impairment. Specifically, the prerequisites forremedial action by EPA
to promulgate appropriate FIPmeasures under all ofthe subsections ofsection 110(c)(1) ofthe Act have already been met,although satisfying only oneis adequate. As explained above, Arizona failed completely to submit any visibility SIP provisions, thereby satisfying the prerequisite in section 110(c)(1)(A). Moreover, EPA, in January 1986, issued a notice ofSIP deficiency meeting the requirements ofsection 110(a)(2)(A) and afforded Arizona an opportunity to submit corrective

measures. Arizona failed to submit the required plan revision to correct this inadequacy and so EPA satisfied the prerequisite in section 110(c)(1)(A).8 5
There was no need to specifically identify Grand Canyon impairment in that notice because the State had been properly informed that the SIP as a whole was inadequate to remedy impairment which DOI certified as existing.in all Class I areas within the State. In addition, EPA's proposed SIP disapproval in March 1987 specifically alerted Arizona to the presence of wintertime impairment in the Grand Canyon and the need forcorrective action. See 52 FR 17804, 17806. Also, in November 1987,EPA disapproved Arizona's SIPfor failure to provide remedial visibility SIPmeasures, thereby satisfying the prerequisite in section 110(c)(1){B). Finally, in letters submitted to the docket for this rulemaking, the State ofArizona has stated its agreement that EPA, and not the State, should proceed to address BART to remedy Grand Canyon

36Prior tothe revisions tosection 110(c)(1) enacted by section 10-(h) ofthe Clean AirAct Amendments of 1990.Public Law 101--54 (November 15, 1990). the failure ofa State to makea required submission in response to aNotice ofSIP inadequacy under section 110(a)(2)(H) was set forth in a separate subsection, 110(c)(1)(C), that hasnow, been merged in to subsection 110(c)(1)(A). 

### impairment without a further specific opportunity forrulemaking by the State. Clearly, under these circumstances, it would serve nopurpose to take the additional steps suggested by SRP as both the letter and spirit ofsection 110(c)(1) have been satisfied3 6

3e

On November 15,1990.President Bush signed into lawthe Clean Air Act Amendments of1990, Public Law 101-549. While the Amendments revised theAct in several areas, they donot include any changes that materially affect either prior FIP actions regarding Arizona orthis rulemaking. In particular. section 102(h) ofthe Amendments revised the language and organization ofsection 110(c)(1) ofthe Act, but didnot affect the standards for adefault inArizona's SIPplanning obligations

orEPA's FIP obligations arisingfrom such failure in any material way. Section 101(c) ofthe Amendments added a savings clause as section 110(n)(1) ofthe revised Act that preserves implementation plan provisions already promulgated bythe Administrator, including those portions oftheArizona FIP thathave already been promulgated. A companion provision, section 108(1) ofthe Amendments, added a savings clause as section 193 oftherevised Act that preserves every regulation, standard rule, notice,orderand guidance promulgated orIssued bythe Administrator, except

as otherwise provided byor inconsistent with the Amendments, orrevised bythe Administrator. Section 108(j) ofthe Amendments adds anew section302(y) to therevised Act thatdefines "federal implementation plan"in pertinent partto

meana plan orportion thereofpromulgated by the Administrator to fill all or a portion ofagap or otherwise correct all or a portion ofan inadequacy in aSIP, and which includes enforceable emission limitations. Section 816 ofthe Amendments added a
new section 169B oftherevised Act thatcalls upon EPAto study andpossibly adopt a regulatory program:toaddress the problem ofregional haze in Class Iareas.

Taken together, the FIP and savings clause provisions constitute an "anti-backsliding" approach by Congress, and donot affect any preexisting actions ofEPA, except tothe extent that

new orrevised substantive provisions call into question the validityofthose actions. Thus, prior visibility FIP actions affecting Arizona. in particular, Arizona's default with respect to itsBART obligation and EPA's assumption ofthat obligation. remain inplace. With respect to outstanding FIP obligations, thereis no indication that Congress intended to disturb such obligations except where the Amendments alter the underlying SIPplanning obligations in a manner that evinces congressional intent to reinstitute State primacy.Thus, for example, a courthas relieved EPA ofa pre-existing obligation to promulgate a FIPto meet the ozone NAAQS inSouthern California, becausethe Amendments granted States additional time to develop theirown attainment plansfor ozone. See Coalition for Clean Airv.EPA. (C.D. Cal., Order granting-motion to vacate settlementagreement, Jan. 9.1991) ("the structure ofthe amended Act, with revamped criteria andtiming for SIPs. andwith

an obvious policy that the States are encouraged to take the lead. withthe potential FPto be the stick that drives them, is clear"). In contrast,with respect to this rulemaking, Congress tookno action to suggest that it intended to alter either the substance

or timing oftherequirement to apply BART to

sources that may reasonably be anticipated to

cause orcontribute to visibility impairment in Class Iareas where, as here, EPA actsunder its present regulations addressing impairment that can be "reasonably attributed" toa source. In particular, theregional haze provisions ofsection 169Bdo not affect thepresent action regarding "reasonably Continued 

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Regarding the purported need fora "final" attribution determination before proceeding to a BART analysis, there is

no support in the regulations for the notion that EPA mustproceed in this fashion. Indeed, 40 CFR 51.302(c)(4) speaks ofa single requirement to "identify and analyze for BART." Inits order ofJuly 6, 1989, the court in EDFv. Reillygranted the EPA's and EDF's joint request that EPA be given a short additional timeto conduct a BART analysis and issue a proposal on the need forBART (this time was further extended at SRP'srequest by the court's order ofJanuary 9, 1990), butthe regulations do not suggest that it is necessary to formalize EPA's voluntary bifurcation of a single decision and make a "final" determination on the first portionbefore proceeding to the second. Nor is it necessary to proceed in the fashion these commenters suggest in order to satisfy the rulemaking requirements ofthe Act of the Administrative Procedure Actbecause neither a "proposed" nora "final" reasonable attribution determination is

a promulgated regulation or other "final action" withinthe meaning ofthose statutes and is not subjecttojudicial review. Rather, it is a preliminary finding that may lead to a final rule or other final action (i.e., a final decision that emission limitationsrepresenting BART are unnecessary, or the imposition of such limitations) that is subjectto review.
E.DiscussionofSeasonalControlsasa BARTEmission Limitation

In a letter datedJanuary 14, 1990, SRP submitted a position paper to EPA raising the issue ofwhether EPA could lawfully provide forthe seasonal application ofpollution control technology in establishing BART. SRP's letter takes the position that the law allows seasonal controls in this case. Forthe reasons summarized below,EPA believes that at this time seasonal controls are not appropriate under the circumstances ofthis rulemaking. However,EPA solicits comments on (1) the appropriate use ofseasonal controls

as BART; and (2)whether, ifseasonal controls may be allowed, therecord of this rulemaking would support imposition ofonly seasonal controls at NGS.

In considering whether EPA's 

### traditional interpretation ofother

attributable" visibilityimpairment under section 169Aand 40 CFR part51, subpart P, andthere are no other new or revised substantive provisions that would relieve EPA of itsobligation to completethis FIPaction. Thus,EPA's obligation to complete this BART rulemaking remains in place. 

### provisions ofthe Clean AirAct regarding emission limitations applies with equal force to BART EPA believes the following relevant statutory provisions and legislative history should be weighed. BART is definedby theAct

as "emission limitations" which "reflect" thebest available retrofit "technology." Seesections 169A(b) and (g)(2), 42 U.S.C. 7491(b) and (g](2). The regulations likewise refer to BART as "emission limitations" and as an "emission standard." 40 CFR 51.302(c)(2)(iii) and 51.302(c)(4)(ii). The Act defines "emission limitation" and "emission standard" to require "continuous" emission reduction. Section 302(k), 42U.S.C. 7602(k). The EPA regulations explicitly require "continuous emission reduction" in any BART emission limitation. 40 CFR 51.301(c). In addition, section 123(a) provides that "[tihe degree ofemission limitation required forcontrol ofany air pollutant under this title shall not be affected in any manner by * * * any * * * dispersion technique," while 

### section 123(b) defines dispersion technique toinclude "any intermittent or supplement control ofair pollutants varying with atmospheric conditions." 42 U.S.C. 7423.



### Thelanguage eventually enacted as section 123 originated in the House version ofthe 1977Amendments. The House committee report defines dispersion techniques as "techniques which seek to reduce concentrations of pollutants not by reducing the amounts ofpollutants emitted into the air, but rather by relying on the dispersion of pollution throughout the atmosphere.""37 (emphasis added).

Although the central focus ofthe congressional deliberations was on tall stacks and short-term adjustments in the amount ofemissions from a source in orderto meet SIPlimits designed to achieve the national ambient airquality standards. EPA requests comments on the extent to which those concerns also apply to seasonal controls and BART emission limitations, which were not explicitly considered in thislegislative history. The House committee report lists several "fundamental policy objections" to intermittent controls or dispersion techniques that may be relevant to thisrulemaking, including dubiousreliability, concern over effects ofsecondary pollutants, transport of pollutants to other areas, acid rain effects, and simple prudence. See H.R. Rep. No. 294 at 82-88. Language nearly identical in pertinent part tothe

5,

H. R. Rep.No. 294, 95th Cong., 1st Sesp.At I1 (1977). 

### language eventually enacted in section 302(k) appears in both the House and Senate bills. In explaining the purpose of. this language, the House committee report states:

By defining the terms "emission limitation," "emission standard," and "standard of performance," the committeehasmade clear that constant orcontinuous means of 

### reducing emissions must be used to meet theserequirements. By the same token, 

### intermittent orsupplemental controls orother temporary, periodicor limited systems of control would not bepermitted asafinal

means ofcompliance. 38



### The Senate committee report elucidates its reason for defining "emission limitation" as follows: "This bill includes a definition ofthe phrase .emission limitations' to clarify the committee's view that the only acceptable basic strategy is one based

on continuous emission control. Intermittent controls or dispersion techniques are unacceptable as a substitute for continuous control of pollutants under this act." s



### The Senate committee report parallels the House committee report in its statement ofreasons for disfavoring intermittent control strategies. The Senate committee report adds that "continuous emission reduction

measures are available, they are reliable, and they are economically justified." 40



### SRP's letter focuses exclusively on section 123 in asserting that seasonal controls are permissible as BART, and doesnot address section 302(k) or the legislative history noted above. In addition, SRP characterizes BART as exclusively directed toward "ambient objectives," citing instances in which EPA has allowed seasonal relaxations 

### inSIP rules intended to achieve national ambient air quality standards. 4 1

### In doing so, SRP assumes that the prier experience regarding SIPs that it cites should govern here. EPA requests comment on SRP's contention that BART is strictly an ambient-based limit. In thisregard, commenters should consider EPA's experience under other technology-based standards.

First,the language and structure ofthe BARTrequirement appear to delineate it

as a technology-based standard. Second,

88 Id.at 92.

35 S. Rep. No. 127. 95th Cong..1st Sess. 94(1977). 401d. at 95. " EPA notes that noneof the examples cited by SRP involve technology-based standards under the Act. In addition, it is notclear that these cases involved "emission Limitations" undersection 110(a)(2)(B) as that term ofart is defined in section 302(k), as opposedto other measures undersection 110(a)(2](b). : Ill II 

### 5187

### Federal Register ] Vol. 56, No. 27 

## / Friday, February 8, 1991 / Proposed, Rules

the overall legislative scheme embodied in the visibility planning requirements of section 169A draw a distinction between the general requirement in section 169A(b)(2) to adopt SIPs that include "such emission limits, schedules of compliance and othermeasures as may be necessary to make reasonable progress," and the explicit requirement in section 169A(b)(2)(A) toemploy BART as one such visibility measure.

Congress appeared to follow a similar pattern regarding the PSD and NSPS programs. For example, Congress adopted the PSD program toprotect against actual or potential adverse effects from pollutants emitted to the ambient air by requiring states to adopt SIPs containing a host ofemission limitations and other measures to achieve the goal ofpreventing significant deterioration ofair quality. See sections 160(1) and 161, 42 U.S.C. 7470(1) and 7471. However, as one such specific PSD measure, Congress required major new or stationary sources to employ a technology-based emission limit-the best achievable control technology. See sections 165(a)(4), 169(3), 42 U.S.C. 7475(a)(4), 7479(3). 

### Similarly, under theNSPS program, EPA must publish a list ofcategories of stationary sources that cause or contribute to air pollution which may endangerpublic welfare, but Congress required EPA to address these source categories contributing to ambient pollution problems through the technology-based new source performance standards. Compare section 111(b)(1)(A), 42U.S.C. 7411(b)(1)(A), with section 111(a)(1), 42 U.S.C. 7411(a)(1). TheEPA solicits comment on the use ofseasonal controls in thisBART rulemaking.

Should EPA decide that facts allow seasonal controls and that the statutory language and legislative history precludes seasonal controls, a possible statutory basis for a seasonal variance would be the procedures contained in the BART exemption provisions of section 169A(c) (2) 

### and (3). and 40 CFR 51.303. The statute explicitly addresses thepossibility ofBART exemptions for large power plants such as NGS but establishes a very high hurdle for granting any such exemption. Itrequires the source owner oroperator to demonstrate to the satisfaction ofthe Administrator "that such powerplant is located at such distance from all [Class I areas] thatsuch powerplant doesnotor will not,by itselfor in combination with other sources, emit any air pollutant which may reasonably be anticipated to

cause or contribute to a significant impairment ofvisibility in any such area." It further requires the

concurrence ofthe appropriate FLM's. Thus,ifsuch a variance or exemption could be allowed, the burden would be upon SRP and/orits co-owners to make the necessary demonstration. Because there would be no need for a BART exemption until such time as final BART emission limits are established, any such request for exemption shouldbe submitted after completion ofthe BART rulemaking in the formof a request for partial (i.e., seasonal) relieffrom any final BART limits thatmight be established as a result ofthis rulemaking. See40 CFR 51.303. Under 

### the exemption regulations, in orderto demonstrate no "significant impairment," i.e., theabsence-of "a level ofimpairment that interferes with the visitor's visual experience of the area," the owner oroperator "should address the frequency, extent, time, intensity and duration ofthe impairment." See45 FR 80084, 80087. Thus, the factual basis for such a demonstration with respect to this case would be a showing that NGS does not contribute to any significant impairment inany Class Iarea In

seasons other than winter. Inthis regard, SRP contends that therecord demonstrates that summer impairment at Grand Canyon is not attributable to NGS (SRPhas not to date addressed potential impacts ofNGS at other Class Iareas in the vicinity, such as Bryce Canyon National Park, ZionNational Park, and Canyonlands NationalPark). The limited information in the record at this time, however, suggests the contrary. 42 43 44 

### As stated earlier.EPA and NPS suspect that emissions from NGS may contribute to regional visibility impairment during the entire year and that a decrease in SO2 emissions from NGS may improve regional visibility in many Class Iareas in the Colorado Plateau. The EPA solicits comments on whether a seasonal variance could be allowed under section 169A(c) in themanner discussed above or under some other statutory authority, on whether such a variance could be considered only after completion ofthis rulemaking, and (in the event thatEPA concludes it would be appropriate to consider a seasonal variance inconjunction with the present proceeding) on the factual question of whether NGS contributes to any

42Summary Statement by*Brand Niemann,March 21 1990.

"Modeling Regional Haze in the Southwest: A Preliminary Assessment ofSource Contribution (Systems Application. Inc. Feb. 1985).

44

Calculations ofthe Haze Impacts ofthe Navajo Generating Station on Grand Canyon and Other National Parks in the "Golden Circle" ofUtahand Arizona (D.A. Latimer Jan. 1991). significant impairment in any Class I

area.
F. TheAdequacyofthe September5, 1989Notice

The SRP asserts that the September 5, 1989 notice was inadequate to meet the requirements set forth in section 307(d)(3) ofthe Act for a statement of basis and purpose to accompany a notice ofproposed rulemaking. The EPA
agrees. However, as explained above,
comments regarding the adequacy ofthe September 5, 1989notice and the draft WHITEX report have been rendered
moot by the fact that the NPS has now issued a final NPS report on WHITEX and by today's notice. This notice contains the complete statement ofbasis and purpose for a regulatory proposal required under section 307(d)(3) ofthe Act, and reopens the comment period on the issue ofreasonably attributable impairment, as well as providing an opportunity to comment on all other issues relevant to this rulemaking. Moreover, EPA believes that insofar as the September 5, 1989 notice addresses the Grand Canyon, the preliminary attribution finding therein was not a regulatory proposal that triggered the requirements ofsection 307(d)(3).

The SRP also complains that EPA has
not disclosed the criteria Itis applying for attribution decisions or its position

on the validity ofthe WHITEX report, and so interested parties are unable to prepare meaningful comments. The EPA disagrees. The analyses In the WHITEX report speak for themselves. Except where specifically noted otherwise, EPA
agrees with the individual analysis conducted by NPS and with the report's conclusions that the NGS is a significant

source ofwintertime visibility impairment in the Grand Canyon. The EPA believes that this notice, together with the WHITEX report and the other analyses thathave been placed in the docket, provides an adequate basis on which to prepare comments on the technical merits ofWHITEX and on the merits oftoday's proposal in general. The EPA will respond to technical
comments when it takes final action on today's proposal.

Regarding SRP's complaint about the absence of "standards" fordeciding whether Grand Canyon impairment is reasonably attributable to NGS, it
appears that SRP is calling upon EPA to set a percentage benchmark for its attribution decision. The EPA tentatively believes that it is neither
necessary nor appropriate under the visibility regulations to establish such a percentage criteria. The provision in 40 CFR 51.303 allowing exemptions from m I 

### 5188

### Federal Register / Vol. 56, No. 27 / Friday, February 8, 1991 / Proposed Rules

BART limits where a source owner or operator demonstrates that it does not

cause or contribute to a "significant" visibility impairment strongly suggests that a percentage cutoffis inappropriate. Consequently, EPAbelieves that today's proposed finding ofreasonably attributable impairment in the Grand Canyon due in a "substantial" or "significant" degree to emissions from NGS is satisfactory. However, EPA solicits comments on whether, in taking final action on today's proposal, it should establish a percentage criterion fordetermining whether impairment is reasonably attributable to a stationary facility.
Format forRemedial Action

With respect to past implementation oftheir visibility requirements and because ofthe large number ofStates involved and the ongoing nature ofthe regulatory requirements, EPA deemed it appropriate to promulgate generic Federal implementing regulations and insert them into the SIP's ofthe affected States. See, e.g., 40 CFR 52.26 (visibility monitoring strategy, implementing 40 CFR 51.305); 40 CFR 52.27 and 52.28 (visibility new source review, implementing 40 CFR 51.307); 40 CFR 

### 52.29 (implementing long-range strategies, 40 CFR 51.306); 40 CFR 51.145 (b)and (c)(incorporating these provisions intothe Arizona SIP). With respect to source attribution and BART, however,Arizona is the only State for which remedial Federal measures are
even potentially needed at this time. Accordingly, EPA proposes to simply follow the appropriate provisions ofthe Part 51 visibility regulations in making *source attribution and BART findings regarding NGS and, ifthose findings result in the imposition ofactual emissions limitations under BART, to amend the visibility FIP forArizona in 40 CFR 52.145 to incorporate such limitations. Nonprecedential Effect ofThis Action

Today's proposal is limited to the rulemaking obligation currently before EPA: To determine whether to require the application ofBART at NGS inorder to remedy visibility impairment in the Grand Ganyon.As such, it has no direct precedential effect on any other rulemaking action EPAmight undertake in the future regarding other existing

sources orClass Iareas.This is so because the outcome of thisrulemaking will be highly dependent upon facts and curcumstances that are unique to this proceeding and thus may notbe decisive forother cases. For example, the tracer studies and other analyses contained In the WHITEX report that are keyed to NGS are not necessarily determinative in any other rulemaking addressing otherpotential sources ofvisibility impairment. Should EPA or State agencies conduct visibility rulemakings regarding other Class I areas and other existing sources ofpollution in the future, they will needto rely on studies and analyses tailored specifically to the circumstances ofthose other areas and

sources in order to makereasoned regulatory decisions. They will notbe able to rely solelyon WHITEX findings that specifically address the Grand Canyon and NGS to determine the existence ofimpairment that is reasonably attributable to any such other source. Likewise, the final BART emission limitthat emerges from this rulemaking will nothave direct precedential effect elsewhere. The statutory requirement that EPAweigh the costs ofcompliance, the expected improvement in visibility, and other BARTfactors before reaching a decision is bynature a case-specific process.

Upon completion offinalrulemaking action regarding NGS, EPA willhave completed its obligations under the settlement agreement in EDFv.Reilly and under the first round ofSIP/FIP planning called for in the visibility regulations. The EPA willthen focus its attention on establishing the visibility transport commissions and conducting the regional haze studies called for in

new section 169B oftheAct added by the Clean Air Act Amendments of1990. In addition, EPAplans to conduct a tracer study ofemissions fromthe Mohave Power Plant.4 5



### Solicitation ofCommentIs

The EPA solicits comments on all aspects to today's proposal to revise the FIP for the State ofArizona to include emission limits for NGS to address the visibility impairment observed during thewinter months in the Grand Canyon.

Specifically, EPA is reopening the comment period forissues pertaining to today's proposed finding that a portion ofthe visibility impairment in the Grand Canyonis reasonably attributable to NGS.

In addition, EPA solicits comments on all aspects oftheBART analysis for NGS including, butnot limited to, the following: Assumptions made in the IAPCS cost model, the model selected to determine the Improvements invisibility expected to occur In the Grand Canyon

as a result ofSOz controls at NGS, the emission limitsrepresenting BART, and the appropriate averaging time to be used to determine compliance, the useof

4"H.R. Rep.900,101st Corgess, 2d Sess., at88 (Oct. 1990). 

### .seasonal controls, and schedule for compliance. The EPA also solicits
comments on the appropriateness of establishing opacity and NO2 limits 

### similar toplants with emission limitations developed over thepast 10 years and NGS'sexisting emission rates. The EPA also solicits comments on the benefit analysis performed in conjunction with theBART analysis and

on the pilotbenefits study submitted to EPAby SRP.

EPA solicits comments on the legal and regulatory issues discussed above and on the format for remedial action.

Finally, SPA solicits comments on updating BART Guideline to delete the NSPS presumption.

TheEPA has established a docket for thisproposal, Docket Number A-89'02A. The docket is an organized and complete file ofall significant information submitted to or otherwise considered byEPA during this proceeding. This docket will serve as the record in the case ofjudicial review under section 307(b) of theAct, 42U.S.C. 7607(b).

Classification

Executive Order No. 12291 requires each Federal agency to determine ifa regulation is a "major"rule as defined bythe order and "to the extent permitted by law," toprepare and consider an RIA in connection with every majorrule.Major rules are defined as those likely toresult In:

(1)An annual cost to the economy of $100million or more; or

(2) 

### A major increase in costs orprices forconsumers orindividual industries;

or(3)Significant adverse effects on competition, employment, investment, productivity, innovation, or international trade.

The EPAhas judged theproposed BART regulation forNGS to be a major rule based on projected annualized costs potentially in excess of$100 million. The EPAhas prepared a preliminary RIA that includes estimates ofcosts, benefits, and netbenefits for three control options. Thepreliminary analysis, titled "Regulatory Impact Analysis ofa Revision oftheFederal Implementation Plan for the State of Arizona to Include SO2 Controls forthe 

### Navajo Generating Station," and an addendum, titled "Addendum to the Regulatory Impact Analysis ofa Revision of theFederal Implementation Plan forthe State ofArizona to Include
S02 Controls for the Navajo Generating 

### Station" are available in DocketA-89- ozA. 5189

### Federal Register 

## / Vol. 56, No. 27 / Friday, February 8, 1991 / Proposed Rules

The preliminary RIA finds that given the estimates and uncertainties captured by the benefit and cost analysis, a 0.10 lbs/MMBtu emission limit will result in potential economic gains to society
among all examined alternatives, i.e.. the net benefits (estimatedbenefits minus estimated costs) are positive. An examination ofless stringent regulatory alternatives (e.g., a 0.30 lbs/MMBtu and 0.50 lbs/MMBtu SO2 emission limit) resulted in smaller but still positive estimated net benefits. Taking into consideration the uncertainties in the analysis, the EPA is proposing a 0.30 lbs/MMBtu emission limit rather than the alternative that produces the maximum estimated economic gains. With implementation ofthe proposed regulation, the cost ofpower generation
at NGS will increase. The projected cost increase is estimated to raise the
average cost ofpower generation by less than 5 percent for utilities using NGS
power. The cost impacts could be lower ifthe acid deposition allowances are sold.

In particular, the cost increase may be partially offset by revenue earned through the sale ofSO2 marketable allowances. The NGS may use this

revenue to recover part ofthe cost of SO2 control technology ormay bank it against the operator's future expansion.

The preliminary RIA was submitted to the Office ofManagement and Budget (OMB) forreview under Executive Order 12291. Written comments from OMB and written EPA response to these
comments are available for public inspection at the docket office cited above. A final RIA will be issued at the time ofthe final rulemaking. PaperworkReduction Act

This rule will impose a modest reporting burden on the owners ofthe NGS to enable EPA to ensure compliance with the emission limits. Because the reporting burden affects only a single source, it is not subject to OMB review under the Paperwork Reduction Act.

Section 317(c) Economic Impact Assessment

The economic impact assessment required by section 317(c) of the Act is incorporated inthe RIA. Regulatory Flexibility Act

Under the Regulatory Flexibility Act (RFA), an agency proposing or promulgating a rule must determine if the rule will have a significant impact on

a substantial number of small entities. If

a significant impact on a substantial number ofsmall entities is anticipated,

an RFA must beprepared. None ofthe 

### owners ofthe NGS areclassified as small according toguidelines developed by the SmallBusiness Administration.

Formost ofthe utilities using NGS power, the impact on utility rates willbe substantially less than 5percent which applies to the most affected utility (Nevada Power Company).

Accordingly, Ihereby certify that the proposed regulation will not have a significant impact on a substantial number ofsmall entities. Therefore. this proposed regulation does not require an RFA.
List ofSubjects in 40 CFR Part52

Air pollution control, Nitrogen dioxide, Particulate matter, Reporting and recordkeeping requirements, Sulfur oxides.

Dated: January 3,1991. F.Henry Habicht, ActingAdministrator.



### For the reasons set out in the preamble, title40, chapter 1,part52 of the Code ofFederal Regulations is proposed to be amended as follows.

PART 52-APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS

1.The authority citation forpart52 continues to read as follows:

Authority: 42 U.S.C. 7401-7642.
2. Section 52.145 is amended by adding paragraph (d) to read as follows: §52.145 

### Visibility protection.

(d)This paragraph is applicable to the fossil fuel-fired, steam-generating equipment designated as Units 1,2,and 3at the Navajo Generating Station in the Northern Arizona Intrastate Region 

### (§81.270 ofthis chapter).

(1)No owner or operator ofthe fossil fuel-fired, steam-generating equipment to which this paragraph is applicable shall discharge orcause the discharge of:

(i)Sulfur oxides into the atmosphere in excess of126 ng/I (0.30 pounds per million British thermal units (lbs/ MMBtu)) heat input. Compliance with this emission limit tobe determined on a 30-day rolling average.

(ii)Nitrogen oxides into the atmosphere inexcess of 210 ng/j (0.50 lbs/MMBtu) heatinput based on a 30- day rolling average.

(iii) Stack emissions which exhibit greater than20percent opacity (6- minute average) except for one 6-minute period per hour of not more than 27 percent opacity.

(iv)The owner or operator ofthe NGS shall install and maintain continuous emission monitors to determine compliance with the emission limitations in paragraphs (d)(1) (i),(ii), and (iii) ofthis section on a continuous basis.This equipment shall meet the specifications listed inappendix Bof40 CFR part 60.The facility shall comply with the qualityassurance procedures found in appendix Fof40 CFR part 60.

(2)The owner oroperator ofthe fossil fuel-fired, steam-generating equipment
to which this paragraph is applicable:

(i)Shall notifythe EPA Regional Office orits designee, ofthe SO 2

### ,NO. oxygen and carbon dioxide emissions, and opacity according to the procedures found in 40 CFR 60.7.

(ii)Shall maintain records according
to the procedures found in 40 CFR 60.7.

(3)The requirements ofparagraphs (d) (1)and (2) ofthis section shall be applicable to one unit at the facility by January 1.1995. two units byJanuary 1, 1997, and all unitsby January 1,1999. [FR Doc.91-3075 Filed2-7-91: 8:45 am]

BILLING COOE 6500-U



### FEDERAL COMMUNICATIONS

COMMISSION

47CFR Part 69

[CC Docket No.78-72,DA 91-371

Common Transport and Dedicated Transport

AGENCY: Federal Communications 

### Commission. ACTION: Proposed rule; Request for 

### information to supplement therecord.
SUMMARY, The Common Carrier Bureau 

### adopted anotice ofproposed rulemaking in 1984 to consider issues relating to the waiver ofthe Commission's Rules prescribing a rate structure for recovering the costs of providing transport access facilities. Since that notice ofproposed rulemaking was adopted, there have been numerous changes in thetelephone industry and in Commission regulations affecting thatindustry. Therefore, we request thatinterested parties file
comments in thisproceeding to update the record. DATES: Comments mustbe received on
or before February 22, 1991;replies must be received on or before March 22, 1991. ADDRESSES: Federal Communications 

### Commission, 1919 M Street, NW., Washington, DC 20554.
FOR FURTHER INFORMATION CONTACT:. 

### Melissa Newman, Policy and Program Planning Division,Common Carrier Bureau (202) 632-9342., 5190