UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

REGION III

 1650 Arch Street

 Philadelphia, Pennsylvania 19103-2029

DATE: 03/29/12

SUBJECT: Approval and Promulgation of Air Quality Implementation Plans; 

Pennsylvania; Nonattainment New Source Review Rules – Technical Support 

Document

FROM: Gerallyn Duke

 Office of Permits and Air Toxics Review

TO: Kathleen Cox, Associate Director

 Office of Permits and Air Toxics Review

I. BACKGROUND

On August 9, 2007, the Pennsylvania Department of Environmental Protection (PADEP) 

submitted a State Implementation Plan (SIP) revision request, pertaining to Pennsylvania’s 

nonattainment New Source Review (NSR) program. This SIP revision is intended to update the 

state’s nonattainment NSR regulations to meet the 2002 NSR Reform measures, make clarifying 

changes to certain nonattainment NSR provisions and to satisfy the requirements of a recent

decision by the United States Court of Appeals for the District of Columbia (D.C. Circuit Court)

regarding antibacksliding (South Coast Air Quality Management District v EPA (South Coast))

1

.

2002 NSR Reform

On December 31, 2002 (67 FR 80186), EPA published final rule changes to 40 Code of Federal 

Regulations (CFR) parts 51 and 52, regarding the CAA’s PSD and nonattainment NSR 

programs. On November 7, 2003 (68 FR 63021), EPA published a notice of final action on the 

reconsideration of the December 31, 2002, final rule changes. The December 31, 2002, and the 

November 7, 2003, final actions are collectively referred to as the ‘‘2002 NSR Reform Rules.’’ 

The 2002 NSR Reform Rules are part of EPA’s implementation of parts C and D of title I of the 

CAA, 42 U.S.C. 7470–7515. Part C of title I of the CAA, 42 U.S.C. 7470–7492, is the PSD 

program, which applies in areas that meet the National Ambient Air Quality Standards

(NAAQS)—‘‘attainment’’ areas—as well as in areas for which there is insufficient information 

to determine whether the area meets the NAAQS—‘‘unclassifiable’’ areas. Part D of title I of

the CAA, 42 U.S.C. 7501–7515, is the nonattainment NSR program, which applies in areas that 

 

1

In 2006, the United States Court of Appeals for the District of Columbia Circuit found in et al, 472 F.3d 882 (D.C. 

Cir 2006) that NSR is a control measure and to weaken its requirements under the SIP would constitute 

impermissible backsliding under the CAA. 
2

are not in attainment of the NAAQS—‘‘nonattainment’’ areas. Collectively, the PSD and 

nonattainment NSR programs are referred to as the ‘‘New Source Review’’ or NSR programs. 

EPA regulations implementing these programs are contained in 40 CFR 51.165, 51.166, 52.21, 

52.24, and part 51, appendix S. The CAA’s NSR programs are preconstruction review and 

permitting programs applicable to new and modified stationary sources of air pollutants 

regulated under the CAA. The NSR programs of the CAA include a combination of air quality 

planning and air pollution control technology program requirements. Briefly, section 109 of the 

CAA, 42 U.S.C. 7409, requires EPA to promulgate primary NAAQS to protect public health and 

secondary NAAQS to protect public welfare. Once EPA sets those standards, states must

develop, adopt, and submit to EPA for approval a SIP that contains emissions limitations and 

other control measures to attain and maintain the NAAQS. Each SIP is required to contain a

preconstruction review program for the construction and modification of any stationary source of 

air pollution to assure that the NAAQS are achieved and maintained; to protect areas of clean air; 

to protect air quality related values (such as visibility) in national parks and other areas; to assure 

that appropriate emissions controls are applied; to maximize opportunities for economic

development consistent with the preservation of clean air resources; and to ensure that any 

decision to increase air pollution is made only after full public consideration of the consequences 

of the decision.

The 2002 NSR Reform Rules made changes to five areas of the NSR programs. In summary, the 

2002 Rules: (1) Provide a new method for determining baseline actual emissions;(2) adopt an 

actual-to-projected actual methodology for determining whether a major modification has 

occurred; (3) allow major stationary sources to comply with PALs to avoid having a significant 

emissions increase that triggers the requirements of the major NSR program; (4) provided a new

applicability provision for emissions units that are designated clean units (Clean Unit test); and 

(5) excluded pollution control projects (PCPs) from the definition of ‘‘physical change or change 

in the method of operation.’’ On November 7, 2003 (68 FR 63021), EPA published a notice of 

final action on its reconsideration of the 2002 NSR Reform Rules, which added a definition for

‘‘replacement unit’’ and clarified an issue regarding PALs.

After the 2002 NSR Reform Rules were finalized and effective (March 3, 2003), industry, state, 

and environmental petitioners challenged numerous aspects of the 2002 NSR Reform Rules, 

along with portions of EPA’s 1980 NSR Rules (45 FR 52676, August 7, 1980). On June 24, 

2005, the United States Court of Appeals for the District of Columbia (D.C. Circuit Court) issued 

a decision on the challenges to the 2002 NSR Reform Rules. New York v. United States, 413 

F.3d 3 (D.C. Cir.2005) (also called New York I). In summary, the D.C. Circuit Court vacated 

portions of the rules pertaining to clean units and PCPs, remanded a portion of the rules

regarding recordkeeping and the term ‘‘reasonable possibility’’ found in 40 CFR 52.21(r)(6) and 

40 CFR 51.166(r)(6), and either upheld or did not comment on the other provisions included as 

part of the 2002 NSR r reform Rules. 

On June 13, 2007 (72 FR 32526), EPA took final action to revise the 2002 NSR Reform Rules to 

remove from federal law all provisions pertaining to clean units and the PCP exemption that 

were vacated by the D.C. Circuit Court. With regard to the remanded portions of the 2002 NSR 

Reform Rules related to recordkeeping, on December 21, 2007, EPA took final action to 

establish that a ‘‘reasonable possibility’’ applies where source emissions equal or exceed 50

percent of the CAA NSR significance levels for any pollutant (72 FR 72607). The ‘‘reasonable 
3

possibility’’ provision identifies for sources and reviewing authorities the circumstances under

which a major stationary source undergoing a modification that does not trigger major NSR must 

keep records. The 2002 NSR Reform Rules require that state agencies adopt and submit

revisions to their SIP permitting programs implementing the minimum program elements of the 

2002 NSR Reform Rules no later than January 2, 2006. (Consistent with changes to 40 CFR 

51.166(a)(6)(i), state agencies are now required to adopt and submit SIP revisions within three 

years after new amendments are published in the Federal Register.) State agencies may meet the 

requirements of 40 CFR part 51 and the 2002 NSR Reform Rules with different but equivalent 

regulations.

Antibacksliding

On April 30, 2004 EPA published the “Phase 1 Rule to Implement the 8-Hour Ozone National 

Ambient Air Quality Standard” (69 Fed. Reg. 23,951) which, among other things, allowed areas 

that had a higher nonattainment classification under the one-hour ozone standard to impose the 

NSR requirements of the new, less stringent eight hour classification. In Pennsylvania, for 

instance, the classification for the Philadelphia ozone nonattainment area changed from serious 

under the one hour standard to moderate under the eight hour standard. The Phase I rule was 

subsequently challenged on a number of points, including the NSR provisions and the D.C.

Circuit Court determined in South Coast, that all one-hour ozone NAAQS major NSR 

requirements must remain in place until an area has attained the one hour standard. 

II. SUMMARY OF ACTION

On August 9, 2007, PADEP submitted a SIP revision request to the EPA Region III. The August 

9, 2007 SIP revision request amends 25 Pa. Code Section 121.1 (relating to definitions) and 25 

Pa. Code Chapter 127 (relating to construction, modification, reactivation and operation of 

sources). Public hearings were held on June 6, June 13, and June 19, 2006. These rules were 

adopted by the Pennsylvania Environmental Quality Board on February 20, 2007 and became 

effective May 19, 2007. 

This approval action will revise the previously-approved version of Pennsylvania’s

nonattainment NSR rules as approved into the Pennsylvania SIP on December 9, 1997 (62 FR 

64722). The state has adopted an automatic incorporation by reference of federal PSD rules at 

§52.21, in its entirety, which was approved as part of the SIP on June 18, 1983. This SIP

revision takes no action on the state’s PSD program. 

III. EVALUATION

EPA last took action on the NSR provisions of the Pennsylvania SIP on December 9, 1997. 

At that time EPA approved a wholesale revision of the state’s pre-construction permitting 

program and included new and revised subchapters A, B, C and E. Pennsylvania had adopted 

the new rules in response to the 1990 Clean Air Act Amendments (CAAA) requirement to 

submit new NSR programs addressing §182. The only subchapter that was not revised was 

subchapter D – the state’s PSD program. 
4

The approved 1997 SIP revision created a framework whereby all sources, except those 

specifically exempt, must comply with the general requirement to obtain a “plan approval” prior 

to construction as outlined in subchapters A and B. These subchapters are generally considered 

the state’s minor NSR program covering minor sources as well as minor changes at major 

sources. Major sources are subject to the additional requirements of subchapters D (PSD) and E 

(nonattainment NSR). Subchapter E also includes additional provisions relating to minor 

changes at major sources for ozone precursors (NOx and VOCs). The latter requires facilities to 

aggregate de minimis increases over a specified period of time. Once the net emissions increase 

(creditable decreases can be used to net over the period of aggregation) equals or exceeds the 

significance threshold for the area, the facility is required to offset the increase at a ratio 

commensurate with the area’s classification. De minimis changes are not subject to a technology 

requirement such as LAER or BACT. Finally, the 1997 SIP revision established the state’s 

banking and trading emissions offset program. 

The 2007 SIP revision retains the currently approved framework for the state’s minor and major 

NSR program but updates the program to incorporate NSR Reform elements in the 

nonattainment NSR provisions, includes antibacksliding measures, and makes other clarifying 

rule changes.

NSR Reform Elements

Prior to NSR Reform, emission increases associated with a physical change or change in the 

method of operation at an existing major source were calculated by comparing past actual 

emissions with the facility’s potential to emit after the change, commonly referred to as the 

actual-to-potential test2. In general, NSR Reform allows facilities to choose between the 

traditional test and a new test that would compare past actual emissions to a projection of future 

actual emissions, so long as the facility makes those projections based on realistic and reliable 

information. In addition, the facility would not be required to establish the projected emissions 

as an enforceable emissions limit. The latter is commonly referred to as an actual-to-actual test. 

As noted above, NSR Reform was challenged on all fronts, including the applicability provisions 

related to the actual-to-actual test and, of importance to the Pennsylvania SIP, the Clean Unit 

test. The Clean Unit test would have allowed facilities that had installed state of the art pollution 

controls within the past 10 years to avoid triggering NSR even when it would be clear that actual 

emissions would increase. The D.C. Circuit rejected the Clean Unit test on the grounds that “the 

CAA unambiguously defines “increases” in terms of actual emissions.” In its concluding 

paragraph on the matter, the Court opined that:

Therefore, because the plain language of the CAA indicates that Congress intended to 

apply NSR to changes that increase actual emission instead of potential or allowable 

emissions, we hold that EPA lacks the authority to promulgate the Clean Unit provision, 

 

2

In 1992, EPA promulgated regulations that created special rules for physical and operational changes at electric 

generating units (EGUs). (57 FR 32314). These rules are commonly called the WEPCO rule because they were 

prompted by litigation involving the Wisconsin Electric Power Company (WEPCO). In those regulations, EPA 

adopted an actual-to-future-actual methodology for all changes at EGUs except for construction of new units or the 

replacement of existing units. 
5

and we vacate that portion of the 2002 rule, 67 Fed. Reg. at 80,279-83 (codified at 40 

C.F.R. § 52.21(x)) as contrary to the statute under Chevron Step 1.

Pennsylvania’s approved 1997 SIP rules allow sources to determine nonattainment NSR 

applicability based on a comparison of past “maximum allowable emissions” emissions to future 

“maximum allowable emissions.” In other words, it allows facilities to use a potential-topotential test to determine NSR applicability. This methodology applies to both the applicability 

test for major NSR as well as in calculating de minimis increases under their minor NSR 

provisions for ozone precursors. By any measure, these rules did not conform to the pre-Reform 

actual-to-potential test or to the present, clear mandate of the D.C. Circuit Court in NY I that 

applicability be based on increases in actual emissions. The 1997 SIP could allow facilities to 

make substantial increases in actual emissions without undergoing review and without applying 

offsets or installing LAER, particularly in nonattainment areas that already have poor air quality. 

By incorporating NSR Reform elements, adoption of the proposed 2007 SIP revision is a 

significant strengthening of the SIP and will finally bring Pennsylvania’s program in line with 

the requirements of the CAA. 

Pennsylvania has adopted all of the NSR Reform measures with some modifications. Areas in 

which Pennsylvania’s regulations differ from their federal counterparts include:

Baseline actual emissions (BAE): 

The look-back period for determining BAE is five years for all facilities, but non-EGUs 

may request up to ten years upon a demonstration that a different period is more 

representative of normal source operation. BAE do not include emissions associated with 

malfunctions. Additionally, the same 24-month period is to be used for all pollutants when 

multiple units are affected by a project unless a facility can demonstrate that another 24-

month period would be more representative. 

Projected actual emissions (PAE):

Projected actual emissions must be incorporated into the required plan approval as an 

emissions limit. 

Reasonable Possibility:

The “reasonable possibility” provision identifies for sources and reviewing authorities the 

circumstances under which a major stationary source undergoing a modification that does not

trigger major NSR must keep records. The 2002 NSR Reform Rules require that state agencies 

adopt and submit revisions to their SIP permitting programs implementing the minimum 

program elements of the 2002 NSR Reform Rules. In the case of the 2007 SIP revision, it wasn’t 

necessary for Pennsylvania to make any changes based on the reasonable possibility provisions 

because facilities that use projected actual emissions with the result that major NSR is not 

triggered, are still required to obtain a permit. These permits require all facilities to maintain and 

report their post-change emissions.
6

AntiBacksliding:

On April 30, 2004, EPA designated Bucks, Chester, Delaware, Montgomery and Philadelphia 

Counties in Pennsylvania as moderate nonattainment under the eight-hour ozone NAAQS and 

revoked the one-hour ozone NAAQS. Under the one-hour ozone standard, Bucks, Chester, 

Delaware, Montgomery and Philadelphia Counties had been designated as severe nonattainment. 

As a result of South Coast, all one-hour ozone NAAQS major NSR requirements in 

Pennsylvania and in the five-county Philadelphia area must remain in place. No other areas on 

Pennsylvania were affected by these antibacksliding provisions. 

Summary of Rule Changes:

Many of the definitions in the approved 1997 SIP have been revised and many terms have been 

added to accommodate the NSR Reform regulations. In addition, Pennsylvania has updated the 

text of some definitions and added definitions that have existed in the federal program for some 

years prior to NSR reform. 

The following table summarizes the changes to the definitions in Section 121.1. Unless 

otherwise noted in the discussion below, all other modifications to definitions are grammatical or 

citation corrections or otherwise minor changes:

25 PA Code Chapter 121.1 Definitions:

Modified definitions “BACT-- best available control technology,” “creation,” 

“de minimis emission increase,” “generation,” “major 

facility,” “major modification,” “major NOx emitting 

facility,” “major VOC emitting facility,” and “secondary 

emissions”

New definitions “Actual emissions,” “Actual PAL for a major facility,” 

“air contamination source,” “allowable emissions,”

“baseline actual emissions,” “begin actual construction,” 

“commence,” “CEMS – continuous emissions monitoring 

system,” “CERMS – continuous emissions rate monitoring 

system,” “CPMS – continuous parameter monitoring 

system,” “creditable emissions decrease,” “deactivation,”

“electric steam generating unit,” “emissions unit,”

“fugitive emissions,” “federally enforceable,” “major 

emissions unit,” “necessary preconstruction approvals or

permits,” “net emissions increase,” “PAL – plantwide 

applicability limit,” “PAL effective date,” “PAL effective 

period,” “PAL major modification,” “PAL permit,” “PAL 

pollutant,” “ PEMS – predictive emissions monitoring 

system,” “project,” “projected actual emissions,”

“regulated NSR pollutant,” “replacement unit,”

“repowering,” “significant,” “significant emissions 

increase,” “significant emissions unit,” “significant net 

emissions increase,” and “small emissions unit.”
7

Deleted Definitions “Extreme ozone nonattainment area,” “marginal ozone 

nonattainment area,” “moderate ozone nonattainment 

area,” “serious ozone nonattainment area,” and “severe 

ozone nonattainment area.”

Except for the revisions made to implement NSR Reform and one-hour ozone anti-backsliding 

provisions, these definition changes reflect minor word changes (e.g., changing “which” to 

“that”). Pennsylvania has also added terms that are intended to help implement their state permit 

programs in general. 

As stated above, State agencies may meet the requirements of 40 CFR part 51 and the 2002 NSR 

Reform Rules with different but equivalent regulations. EPA is proposing approval of the 

following revisions and additions, including definitions for terms that differ from the federal 

rules. Departures from the 2002 federal rules and EPA’s approval of these deviations are 

indicated below. 

Section Status Description NSR 

Reform?

121.1 Modified

text

Added definition of “actual emissions.” Varies from 

federal definition in two ways: (1) requires written 

determination when owner or operator justifies use of a 

consecutive 24-month period different than the 24-

month period immediately preceding normal (2) does 

not presume that source-specific allowable emissions for 

the unit are equivalent to the actual emissions of the unit 

no

121.1 Modified 

text

Added definition of “actual PAL for a major facility” 

which conforms with the federal definition of “actuals 

PAL”

yes

121.1 Modified 

text

Added definition of “air contamination source.” This 

term is included in Section 3 of Pennsylvania’s Air 

Pollution Control Act (APCA)(35 P.S. §4003)

no

121.1 Modified 

text

Added definition of “allowable emissions.” Conforms 

with federal definition and also adds a fourth 

requirement that conforms with 40 CFR 51.165(f)(4)(A) 

to assure that PAL limits are enforceable as a practical 

matter

no

121.1 Modified 

text

Added definition of “Baseline actual emissions” (BAE). 

Language in definition mirrors that in the federal 

definition

yes

121.1 Modified 

text

Added definition of “Begin actual construction” which 

conforms with federal definition

no
8

Section Status Description NSR 

Reform?

121.1 Modified 

text

Added definition of “Continuous emissions monitoring 

system (CEMS)” which mirrors the federal definition

yes

121.1 Modified 

text

Added definition of “Continuous emissions rate 

monitoring system” (CERMS) which mirrors the federal 

definition

yes

121.1 Modified 

text

Added definition of “Continuous parameter monitoring 

system” (CPMS) which mirrors the federal definition

yes

121.1 Modified 

text

Added definition of “Commence” which pertains to 

extensions under §127.13 and conforms to federal 

definition

no

121.1 Modified 

text

Modified definition of “Creation” pertaining to emission 

reduction credits (ERCs) for emission offset purposes

no

121.1 Modified 

text

Added definition of “creditable emissions decrease” in 

§121.1 

121.1

127.215

Modified 

text

Added definition of “deactivation.” This term is 

included to clarify reactivation requirements under 

§127.11a and 127.215 as well as ERC application 

procedures under §127.207(2)(i)

no

121.1 Modified 

text

Modified definition of “de minimis emissions increase” 

to clarify that a change by itself that is less than 

significant would be a de minimis emissions increase

no

121.1 Modified 

text

Added definition of “Electric utility steam generating 

unit” which mirrors the federal definition

no

121.1 Modified 

text

Added definition of “Emissions unit” which conforms 

with the federal definition. As part of definition of 

“emissions unit,” added definition of “new emissions 

unit” and “existing emissions unit” both which conform 

to federal definition

yes

121.1 Modified 

text

Added definition of “Federally enforceable” which

mirrors the federal definition

no

121.1 Modified 

text

Added definition of “fugitive emissions” which mirrors 

the federal definition

no

121.1 Modified 

text

Modified definition of “generation” to specify that the 

term pertains to an owner or operator of an air 

contamination source, emissions unit or facility with 

respect to emission reduction credits (ERCs)

no
9

Section Status Description NSR 

Reform?

121.1 Modified 

text

Added definition of “major emissions unit” which is 

used in §127.18(k)(5)(l) for calculating a PAL and 

conforms to federal term

yes

121.1 Modified 

text

Added definition of “major facility” which is used in 

lieu of and consistent with the federal definition of 

“major stationary source” in most respects. Two 

differences make PA’s definition more inclusive: (1) As 

an anti-backsliding measure, PA includes fugitive 

emissions when determining the status of a facility 

rather than considering fugitive emissions for just the 28 

source categories listed in the Federal definition (2) 

PA’s lower emissions threshold for CO in nonattainment 

areas does not include the federal caveat, “where 

stationary sources contribute significantly to CO levels 

in the area (as determined in rules issued by the 

Administrator).”

no

121.1 Modified 

text

Added definition of “major modification.” Note the 

following differences: (1) Definition includes in Subpart 

(ii) a de minimis increase that would result in 

exceedence of the significance threshold (2) 

Temporary clean coal technology demonstration 

projects are not exempted from the definition. 

Definition does not include any increases in VOC 

emissions in extreme ozone nonattainment areas as set 

forth in 40 CFR 51.165(a)(v)(F), but no extreme ozone 

nonattainment areas are designated in PA.

yes

121.1 Modified 

text

Modified definition of “Major NOx emitting facility” to 

ensure that reasonably available control technology 

(RACT) remains applicable to major stationary sources 

of NOx and VOCs in Bucks, Chester, Delaware, 

Montgomery or Philadelphia counties. Facilities in 

these counties which emit or have the potential to emit 

at least 25 tons per year (tpy) of NOx will be considered 

major facilities and be subject to the requirements 

applicable to major facilities located in a “severe” 

nonattainment area of ozone. This provision prevents 

backsliding related to revocation of the former one-hour 

ozone standard. Retained former emissions thresholds 

for facilities located in extreme and serious 

nonattainment areas as well as in ozone transport 

regions.

no

121.1 Modified Modified definition of “Major VOC emitting facility” to no
10

Section Status Description NSR 

Reform?

text ensure that RACT remains applicable to major 

stationary sources located in Bucks, Chester, Delaware, 

Montgomery or Philadelphia counties. These facilities 

that emit or have the potential to emit at least 25 TPY of 

VOCs will be considered major facilities and be subject 

to the requirements applicable to major facilities located 

in a “severe” nonattainment area of ozone. This 

provision prevents backsliding related to revocation of 

the former 1-hour ozone standard. Retained former

emissions thresholds for facilities located in extreme and 

serious nonattainment areas as well as in ozone transport 

regions.

121.1 Modified 

text

Added definition of “Necessary preconstruction 

approvals” which conforms with federal definition 

under 40 CFR 51.165(a)((1)((xvii).

no

121.1 Modified 

text

Added definition of “net emissions increase” which 

refers to 127.203a(a)(4) and generally conforms with the 

federal definition at 40 CFR 51.165(a)(1)((vi). The 

difference in lookback period (see Baseline Actual 

Emissions Lookback, above) is noted.

yes

121.1 Modified 

text

Added definition of “plantwide applicability limitation” 

(PAL)

yes

121.1 Modified 

text

Added definition of “PAL effective date” yes

121.1 Modified 

text

Added definition of “PAL effective period” yes

121.1 Modified 

text

Added definition of “PAL major modification” yes

121.1 Modified 

text

Added definition of “PAL permit” yes

121.1 Modified 

text

Added definition of “PAL pollutant” yes

121.1 Modified 

text

Added definition of “Predictive emissions monitoring 

system (PEMS)” which conforms with the federal 

definition

yes

121.1 Modified 

text

Added definition of “project” which is similar to the 

federal definition at §51.165(a)(1)(xxxix) but is more 

inclusive as it applies to a facility and thereby includes 

minor as well as major sources. “Project” applies to 

yes
11

Section Status Description NSR 

Reform?

major NSR and PA’s De Minimis Program, which is 

already part of the PA SIP.

121.1 & 

127.203

a(a)(5)

Modified 

text

Added definition of “projected actual emissions” which 

is at least as stringent as federal requirements

yes

121.1 Modified 

text

Added definition of “regulated NSR pollutant” which 

conforms with the federal definition.

no

121.1 Modified 

text

Added definition of “replacement unit” which includes 

all 4 criteria that are included in the federal definition

yes

121.1 Modified 

text

Modified definition of “secondary emissions” which 

mirrors federal definition

no

121.1 Modified 

text

Added definition of “significant” with values for 

significant emissions rates for CO, NOx, SOx, Ozone, 

Lead and PM-10 that mirror the significant emissions 

rates set forth in the federal regulations.

no

121.1 Modified 

text

Added definition of “significant emissions increase” that 

conforms with the federal definition. 

no

121.1 Modified 

text

Added definition of “significant emissions unit” that 

conforms with the federal definition in §51.165(f)(2)(xi) 

for the purpose of using PALs.

yes

121.1 Modified 

text

Added definition of “significant net emissions increase.” 

No definition of “significant net emissions increase” is 

set forth in the federal regulations. Nonetheless, PA’s 

definition comports with the meaning of the term which 

is used in the federal rules.

no

121.1 Modified 

text

Added definition of “small emissions unit” that 

conforms with the federal definition in §51.165(f)(2)(iii) 

where PALs are used.

yes

25 PA Code Chapter 127. Construction, Modification, Reactivation and Operation of 

Sources, Subchapter B. Plan Approval Requirements:

Section Status Description NSR 

Reform?
12

Section Status Description NSR 

Reform?

127.13

(b)

Modified PADEP may extend the 18-month period to 

construct, modify or install an air contamination 

source under a valid plan approval upon a 

satisfactory showing that an extension is justified.

no

25 PA Code Chapter 127. Construction, Modification, Reactivation and Operation of 

Sources, Subchapter E. New Source Review:

*NOTE: Sections 127.201 (d) through (f), 127.201a, 127.203a and 127.218 are new. See 

Descriptions below.

Section Status Description NSR 

Reform?

127.201(c) Modified Corrected language regarding application of 

NSR to include attainment areas for ozone and 

within an ozone transport region that emits or 

has PTE at least 50 tpy of VOC or 100 tpy of 

NOx. Added language to include a facility 

within a basic nonattainment area and located 

within an ozone transport region as also to be 

considered a major facility and subject to 

requirements applicable to a major facility 

located in a moderate nonattainment area. 

Deleted term “stationary” related to major 

facility as §127.14 specifically exempts mobile 

sources from plan approval requirements.

no

127.201(d) Added Language on general applicability of provisions 

of Subchapter E 

some 

parts

127.201(e) Added More stringent rule applies in event of 

inconsistency between rules.

no

127.201(f) Added Facilities located in Bucks, Chester, Delaware, 

Montgomery or Philadelphia Counties that emit 

or have potential to emit at least 25 tpy VOC or 

NOx are subject to requirements applicable to a 

major facility located in a severe nonattainment 

area for ozone.

no

127.201a Added Measurements, abbreviations and acronyms some 

parts

127.202 Modified Changed effective date and clarified that special 

permit requirements apply to facility owner or 

operator

no

127.203(a) Modified Replaced §127.203(a) (relating to facilities subject to No. Ozone 
13

Section Status Description NSR 

Reform?

special permit requirements) with an amended 

proposal which applies to the construction of a new 

major facility or modification at an existing facility 

located in a nonattainment area or located in 

attainment or unclassified area, which impacts a 

nonattainment area in excess of certain significance 

levels. Lower threshold for applicability to include 

facilities with emissions below 100 tpy where these 

facilities are major.

antibacksliding 

127.203(b) Modified Replaced §127.203(b) (also relating to facilities 

subject to special permit requirements) with an 

amended proposal which includes provisions that 

would apply to an owner or operator of a facility in 

Bucks, Chester, Delaware, Montgomery or 

Philadelphia Counties or an area classified as a 

serious or severe ozone nonattainment area.

No. Ozone 

antibacksliding

127.203(c) 

through (f)

Modified Replaced §127.203(b) (also relating to facilities 

subject to special permit requirements) with an 

amended proposal which identified when the NSR 

requirements apply and do not apply to owners and 

operators of facilities. Cites applicability procedures 

under §203a and offset requirements under §205(3) 

No. Ozone 

antibacksliding

127.203a Added Applicability determination. Includes provisions to 

determine net emission increases, baseline actual 

emissions, and projected actual emissions. 

No. Ozone 

antibacksliding

127.204 Modified Clarification some 

parts

127.205 Modified Special permit requirements. Adds provisions as to 

when LAER applies to a proposed modification 

within the contemporaneous period of a proposed 

emissions increase and when emission offsets are 

required for the entire net emission increase that 

occurred over the contemporaneous period.

yes

127.206 Modified Clarification no. 

127.207 Modified Creditable emissions decrease or ERC generation 

and creation. Amended to prohibit emission 

reductions necessary to meet state-only minor NSR 

and allowance-based programs required by the CAA 

or APCA to be used to generate emission reduction 

credits. 

no. 

127.208 Modified ERC use and transfer requirements. Minor 

clarifications. Provides that an owner or operator of 

a facility that is subject to allowance-based programs 

may generate, create, transfer and use ERCs in 

accordance with Chapters 127 and 145 (relating to 

no
14

Section Status Description NSR 

Reform?

interstate pollution transport reduction). Provides 

limited allowance for obtaining ERCs from another 

nonattainment area, consistent with federal 

requirements for offsetting emissions at 40 CFR 

51.165(a)(3)(iii)(F).

127.209 Modified ERC registry system. Clarification. no

127.210 Modified Offset ratios. Clarification. no

127.211 Modified Deleted and remaining applicable provisions were 

moved to new §203a.

no

127.212 Modified Portable facilities. References to PM-10 precursors 

were deleted.

no

127.213 Modified Construction and demolition. Clarification. no

127.214 Rescinded Rescinded former Exemption section. no

127.215 Modified Reactivation. Clarification. Also provides that a 

facility which is deactivated in accordance with 

subsection(a) may create ERCs only if an ERC 

registry application is filed within two years of 

deactivation.

no

127.217 Modified Clarification no

127.218 Added New PALs provisions yes

IV. CONCLUSION

Pennsylvania’s August 9, 2007 proposed SIP revision amending Pennsylvania’s NSR 

construction, modification, reactivation and operation permit programs at 25 Pa. Code Section 

121.1 and 25 Pa. Code Chapter 127, significantly strengthens the existing SIP and is consistent 

with the federal program requirements for NSR set forth at 40 CFR 51.165.

V. RECOMMENDED AGENCY ACTION

I recommend approval of the 2007 SIP revision amending the state’s rules at 25 Pa. Code, Part I, 

Subpart C, Article III, “Air Resources,” Chapter 121, “General Provisions,” Sections 121.1 

“Definitions” and 127 “Construction, Modification, Reactivation and Operation of Sources”.