UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

REGION 4 

ATLANTA FEDERAL CENTER 

61 FORSYTH STREET 

ATLANTA, GEORGIA 30303-8960 

Ms. Sheila C. Holman 

Director 

Division of Air Quality 

North Carolina Department of 

Environment and Natural Resources 

1641 Mail Service Center 

Raleigh, North Carolina 27699-1641 

Dear Ms. Holman: 

March 9, 2011 

As we discussed recently with you and your staff, the U.S. Environmental Protection 

Agency (EPA) has determined that it is important that we clarify our interpretation and 

expectations regarding Federal Land Manager (FLM) notification and visibility assessment 

requirements applicable to proposed new and modified sources subject to the Clean Air Act's 

New Source Review (NSR) program. We appreciate the investment of your time in trying to 

resolve these complex issues as well as your commitment to implement these requirements in 

accordance with EPA's interpretation of the applicable federal regulations and North Carolina's 

approved state implementation plan (SIP). There are, however, some statements made by the 

North Carolina Department of Environment and Natural Resources (NC DENR) in its recent 

filing with the North Carolina Environmental Management Commission (EMC) ("Respondent's 

Written Exceptions and Argument") and the presentation entitled "PSD Permitting - The State 

Program, EMC Meeting- March 10,2011" that do not accurately reflect EPA interpretations of 

its regulations. Therefore, we have concluded that it is in the best interest of all concerned for 

EPA to explain exactly how it expects North Carolina as well as other states to implement the 

FLM notification and visibility assessment requirements. 

Regarding North Carolina's obligation to notify the FLM of any proposed new major 

sources or major modifications to existing sources that "may affect" visibility as required 

pursuant to 40 C.F.R. § 307(a)(l), we recognize and appreciate that NC DENR has committed to 

provide the FLM with timely notice of any such proposed source. As we discussed, EPA expects 

NC DENR to interpret the phrase "may affect" as it appears in North Carolina's SIP (and in NC 

DENR's recently promulgated revisions at 15A NCAC 02D.0530(t)(2) and 15A NCAC 

02D.0531(m)(3)) consistent with the interpretation provided in EPA's New Source Review 

Workshop Manual (draft, Oct. 1990). Specifically, a proposed new or modified source "may 

affect" visibility in a Class I area if it would be located within 100 kilometers (km) of a Class I 

area, or if the source would be located further than 100 km from a Class I area but other factors 

(such as the proposed source's size) raise concerns about potential visibility impacts. Under 

such circumstances, EPA expects NC DENR to provide the FLM with written notification of the 

Internet Address (URL) • http://www.epa.gov 

Recycled/Recyclable. Prinled wHh vegetable on Based Inks on Recycled Paper (Minimum 30% Postconsumer) 
proposed new or modified source "within 30 days of receipt of and at least 60 days prior to 

public hearing by the State on the application for a permit to construct." See 40 C.F.R. § 

51.307(a)(1). EPA disagrees with the interpretation of "may affect" provided by NC DENR to 

the EMC in its recent briefing, specifically, that the term "may affect" is synonymous with "has 

the potential to exceed a Class I increment." See Respondent's Written Exchange and Argument, 

p. 4; see also pp. 20-26. The FLM notification requirement is not related to or contingent upon 

the analysis performed to determine whether the Class I increment is exceeded. 

As we discussed on a recent call with your staff, EPA's regulations instruct that the FLM 

notification described above must "include an analysis of the anticipated impacts on visibility in 

any Federal Class I area." See 40 C.F.R. § 51.307(a)(1). This analysis involves an assessment of 

how a proposed new or modified source's emissions would affect visibility as compared against 

what visibility would be in a Class I area under natural conditions. The requirement that the 

visibility assessment evaluate the source's impact on natural conditions is clearly stated in EPA's 

regulations. Specifically, the regulations define "adverse impact on visibility" as "for purposes 

of section 307, visibility impairment which interferes with the management, protection, 

preservation, or enjoyment of the visitor's visual experience of the Federal Class I area." 40 

C.F.R. § 51.301 (emphasis added). The term "visibility impairment" is defined as "any humanly 

perceptible change in visibility (light extinction, visual range, contrast, coloration) from that 

which would have existed under natural conditions." Id. (emphasis added). Finally, "natural 

conditions" is defined as "naturally occurring phenomena that reduce visibility as measured in 

terms oflight extinction, visual range, contrast, or coloration." Id. In sum, under the plain 

language of the federal regulations, the required assessment of a proposed new or modified 

source's visibility impacts must involve an analysis of how the project's emissions would impact 

natural conditions. The regulatory provisions quoted above are expressly incorporated into 

North Carolina's SIP and are binding on NC DENR. 

EPA disagrees with NC DENR's contention in its briefing to the EMC that EPA requires 

the adverse impact analysis to be "based on current background visual range conditions." See 

Respondent's Written Exchange and Argument, p. 5. As explained above, EPA's regulations 

unambiguously require that the visibility assessment involve an analysis of the project's visibility 

impacts as compared to "that which would have existed under natural conditions." This does not 

mean, however, that current conditions are irrelevant to the ultimate determination of whether 

the visibility impairment caused by a proposed new or modified source rises to the level of an 

"adverse impact on visibility." As provided in EPA's regulations, such a determination involves 

a broad examination of whether any visibility impairment would "interfere[] with the 

management, protection, preservation, or enjoyment of the visitor's visual experience of the 

Federal Class I area." 40 C.F.R. § 51.301. Current visibility conditions may be relevant to that 

determination. Furthermore, even if the FLM ultimately concludes that a proposed new or 

modified source will have an adverse impact on visibility, the state retains the right to decide 

differently and authorize the source's construction. See 40 C.F.R. § 51.307(a)(3). In making 

such a decision, the State can consider current visibility conditions. 

Finally, please note that in accordance with EPA's regulations, it is the State's 

responsibility to provide the FLM with modeling results demonstrating a project's anticipated 

visibility impacts as measured against natural conditions. See 40 C.F.R. § 307(a)(1). The State 

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must provide such information to the FLM at the time that it provides the FLM with notice of the 

proposed new or modified source. See, id. North Carolina's SIP-approved NSR regulations 

instruct that this analysis shall be "provided by the source." See 15A NCAC 02D.0530(q)(1) 

(EPA approval date Oct. 15, 1999) and 15A NCAC 02D.0531(i)(2) (EPA approval date Nov. 10, 

1999). 

Thank you for your willingness to work together with EPA and the FLM to ensure that 

the construction of new major sources or major modifications to existing sources will not result 

in an adverse impact on visibility in any Class I area. We are hopeful that improved 

communication amongst the three agencies regarding their expectations with respect to the 

protection of visibility and other air quality related values will avoid any future 

misunderstandings. 

cc: Sandra Silva, Chief, 

Branch of Air Quality, FWS 

Sincerely, 

~~ JI~,~-t Beverly H. Banister 

Director 

Air, Pesticides and Toxics 

Management Division 

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