 

Revision to Maine’s State Implementation Plan 

Meeting the Interstate Air Pollution Transport Requirements of Clean Air
Act Section 110(a)(2)(D)(i) 

March 6, 2008



Revision to Maine’s State Implementation Plan 

Meeting the Interstate Air Pollution Transport Requirements of Clean Air
Act Section 110(a)(2)(D)(i) 

 

Introduction

On July 16, 1997 PM2.5, the U.S. Environmental Protection Agency (EPA)
issued the 8-hour ozone and national ambient air quality standards
(NAAQS).  The issuance of these NAAQS started a timeline in which states
were required to submit State Implementation Plans (SIPs) that satisfy
the applicable requirements under section 110(a)(1) and (2) of the 1990
Clean Air Act Amendments (CAA) within three years, or July 2000.  Among
these required SIP elements is the need to address interstate transport
of pollutants pursuant to section 110(a)(2)(D) (i).

Section 110(a)(2)(D)(i) of the CAA requires each State to submit a SIP
prohibiting emissions that adversely affect another State.  More
specifically, Section 110(a)(2)(D)(i) requires each State to submit a
SIP that shall:

“(D) contain adequate provisions-

prohibiting, consistent with the provisions of this title, any source or
other type of emissions activity  within the State from emitting any air
pollutant in amounts which will-

contribute significantly to nonattainment  in, or interfere with
maintenance by, any other State with respect to any such national
primary or secondary ambient air quality standard, or

interfere with measures required to be included in the applicable
implementation plan for any other State under part C to prevent
significant deterioration of air quality or to protect visibility.”

On April 25, 2005, the EPA notified States of their failure to submit
SIP submittals addressing the interstate transport of pollutants related
to ozone and PM2.5 in downwind states.   The April 25, 2005 finding of
failure to submit the required SIP elements started a 24-month clock for
EPA to issue a Federal Implementation Plan (FIP) to address the
requirements of section 110(a)(2)(D)(i), unless a State makes the
required submission and EPA approves this submissions within that
24-month period.

State Implementation Plan Submission Requirements Under Section
110(a)(2)(D)(i)

In 2005, EPA promulgated the Clean Air Interstate Rule (CAIR) , whereby
EPA made an affirmative finding that NOx emissions from sources in 24
states and the District of Columbia contribute significantly to
nonattainment and interfere with maintenance of the 8-hour ozone
standard in other downwind states.  The CAIR rulemaking also found that
SO2 and NOx emissions from sources in 23 states and the District of
Columbia contribute significantly to nonattainment and interfere with
maintenance of the PM2.5 standards in other downwind states.

In the CAIR, EPA determined that those states subject to the CAIR will
meet their section110 (a)(2)(D)(i) obligations to address the
significant contribution and interference with maintenance requirements
through compliance with the CAIR requirements.  As a result, these
states are not required to submit a separate SIP revision satisfying the
section 110(a) (2)(D)(i) requirements.  Conversely, States that were not
subject to CAIR must submit a SIP amendment addressing “significant
contribution’ and “interference with maintenance” requirements for
both the 8-hour ozone and PM2.5 NAAQS.  In addition, all states (both
those within the CAIR program and without) must also make a submission
with respect to the “prevention of significant deterioration” and
“protect visibility” requirements of Section 110(a)(2)(D)(i).

Maine was not found to contribute significantly or interfere with
maintenance of either the 8-hour ozone or PM2.5 NAAQS during the CAIR
rulemaking, so must address both of these requirements, along with the
“prevention of significant deterioration” and “protect
visibility” requirements of section 110(a)(2)(D)(i).

I.  Significant Contribution or Interference with Maintenance of the
8-Hour Ozone and PM2.5 NAAQS in Another State

A.  The 8-Hour Ozone NAAQS

Maine previously submitted technical analyses demonstrating that NOx
emissions in Maine do not significantly contribute to nonattainment or
interfere with the maintenance of the ozone NAAQS in any other 8-hour
ozone nonattainment area.  On March 24, 2005, the Maine DEP submitted an
exemption request from the NOx control requirements contained in section
182(f) of the CAA for Northern Maine.  This exemption request was based
on the demonstration that NOx emissions in this multi-county area are
not impacting Maine’s (formerly) 8-hour nonattainment, or other 8-hour
ozone nonattainment 

areas in the Ozone Transport Region (OTR) during times when elevated
ozone levels are monitored in these areas.  

The Department’s technical justification for the request relied
primarily upon back trajectories using the HYSPLIT (HYbrid
Single-Particle Lagrangian Integrated Trajectory) model.   The
Department created back trajectories for each day that experienced an
8-hour ozone exceedence in either of Maine’s nonattainment  areas
during the period from 1998 through 2004.  When 8-hour exceedences were
recorded for a given day in either of Maine’s 8-hour nonattainment
areas, back trajectories were run from locations in each of the
nonattainment areas.  For each ozone exceedence that was analyzed, back
trajectories were run for each hour that recorded ozone in excess of
0.08 parts per million, and run for multiple heights in the atmosphere. 
In all, the Department ran more than 1000 back trajectories for 61
exceedence days during the 1998 through 2004 period.  

The Department then analyzed each of these back trajectories to see if
there was a potential impact from the NOx waiver area.  The Department
supplemented these back trajectories with NOx emission inventory
information for the entire OTR, and additional meteorological analyses
to further show that the NOx waiver area does not contribute to ozone
nonattainment in the two Maine nonattainment areas or anywhere else in
the OTR.  As noted in EPA’s proposed approval of Maine’s NOx
Exemption request (70 FR pages 49526-49530) “Whenever there are 8-hour
ozone exceedences in New Hampshire or Massachusetts, the two states
nearest to Maine, the winds are not from Maine.  Therefore, Maine does
not contribute to ozone nonattainment in Massachusetts nor New
Hampshire, the only two states in the OTR, outside of Maine, where it is
reasonable to expect that Maine’s emissions might potentially
contribute to ozone nonattainment.”

B.  The PM2.5 NAAQS

The Department conducted a trajectory analysis using HYSPLIT online to
create the trajectories included in this analysis and demonstrate that
Maine does not contribute to high levels of PM2.5 in the New York/New
Jersey/Connecticut/Pennsylvania nonattainment area.  

The National Oceanic and Atmospheric Administration (NOAA)’s Air
Resources Laboratory HYSPLIT model is a computer model used to create
and map trajectories.  The model uses gridded meteorological data.  For
more information about HYSPLIT please refer to the following document:
“Description of the HYSPLIT 4 Modeling System by Draxler and Hess.” 
The model was set to include vertical velocity.  The archived ETA Data
Assimilation System (EDAS) meteorological (MET) data set was used
because this was the most consistently available MET data set.  EDAS
data at 80km spacing was available prior to December 2003.  The
trajectories created for 2004 and 2005 events utilized the EDAS 40km MET
files.  

For each run, the HYSPLIT model generates both a graphical presentation
of the trajectories and a text file.  A trajectory is a three
dimensional representation of the path an air parcel followed based on
forecast or archived meteorological data.  A backward trajectory is the
path the parcel took to reach a specific point in time and space, while
a forward trajectory is the path the parcel followed upon leaving a
specific time and place.  The text file contains information about the
hourly endpoints along each trajectory path including the location in
time and space.  Hundreds of endpoint text files were subsequently
loaded into an Access database, which was then mapped in ARCMAP, a
geographical mapping tool used within the Department.  The maps visually
display thousands of endpoints allowing the viewer to readily identify
the transport patterns.

 

The analysis covered data from 2001 through 2005.  Connecticut (CT)
contains the closest portion of any PM2.5 nonattainment area in the U.S.
 Days were chosen when at least 5 sites in CT’s portion of the
NY/NJ/CT/PA nonattainment area monitored PM2.5 24-hr average
concentrations of greater than 29.9 micrograms per cubic meter (µg/m3)
to avoid days when only local emissions contributed.  The value of 29.9
µg/m3 was chosen so that it looked at all days below the new (Dec.
2006) 24-hr PM2.5 NAAQS of 35 µg/m3 and gave a large enough sample to
show potential contributions to the annual PM2.5 nonattainment status of
the NY/NJ/CT/PA PM2.5 nonattainment area.  

36-hour back trajectories from a point in southwestern CT (the majority
of CT’s fine particle monitors are located in the southwestern corner)
were created for each hour of the day and 24-hour forward trajectories
from Portland, ME starting at 12z the day before were created.  These
trajectories were started at 3 heights (100m, 250m & 500m) within the
lower half of the boundary layer.  The results are displayed on maps in
the following figures.

Figures 1 through 3 display back trajectories from CT at 100m, 250m and
500m respectively.  On high PM2.5 days, back trajectories from CT rarely
pass through or near Maine.  The next three figures display forward
trajectories from Maine at 100m, 250m and 500m respectively.  When PM2.5
is high in CT, forward trajectories from Maine rarely pass through or
near the monitor locations in CT and when trajectories do pass over CT
the altitude is relatively high.  

In conclusion, Maine does not contribute to the NY/NJ/CT/PA PM2.5
nonattainment satus and furthermore it is obvious that Maine doesn’t
contribute toward nonattainment of any PM2.5 nonattainment area in the
U.S.

Figure 1- 100m Back Trajectory from CT

Figure 2- 250m Back Trajectory from CT

Figure 3- 500m Back Trajectory from CT

Figure 4- 100m Forward Trajectory from ME

Figure 5- 250m Forward Trajectory from ME

Figure 6- 500m Forward Trajectory from ME

EPA Modeling Analysis for the CAIR Rulemaking

The Department’s analysis is supported by EPA modeling conducted as
part of the 2005 Clean Air Interstate Rule (CAIR) rulemaking. EPA
utilized two different techniques (source apportionment and zero-out
modeling) to quantify the impact of emissions in specific upwind states
on projected downwind nonattainment areas for 8-hour ozone.  The
zero-out and source apportionment modeling techniques provide different
technical approaches to quantifying the downwind impact of emissions in
upwind states.  Zero-out modeling provides an estimate of downwind
impacts by calculating the difference between the model estimates from a
base case run to the estimates from simulation in which the base case
man-made emissions are removed from a specific state.  In source
apportionment techniques, the contributions from many individual source
areas (or categories) to ozone formation are estimated in a single model
run.  Source apportionment modeling tends to show a greater magnitude
and frequency of contributions than the zero-out modeling, but neither
technique is clearly superior to the other for evaluating contributions
to ozone from various emissions sources.

Using the zero-out and source apportionment techniques, EPA determined
which states contribute significantly to nonattainment in the 40
downwind receptor counties that were modeled.  Of the 31 states included
in the assessment of interstate ozone contributions, 25 states and the
District of Columbia were found to have emissions which make a
significant contribution to downwind 8-hour ozone nonattainment.  Maine,
along with five other states was found to not make a significant
contribution to downwind ozone nonattainment.

State by state zero-out modeling was also used as the modeling
techniques to quantify the contribution from SO2 and NOx emission in
individual states to future PM2.5 nonattainment in other states.  As
part of the zero-out modeling technique, EPA removed the 2010 Base Case
anthropogenic emissions of SO2 and NOx from 37 states in the east on a
state-by-state basis in different CMAQ modeling runs.  EPA then used the
modeled contribution from each upwind state to PM2.5 at each of the 113
2010 Base year “modeled plus monitored” nonattainment sites in other
states.  The maximum contribution from among the set of downwind
contributions was then selected as the maximum downwind contribution.  

EPA utilized a criteria of 0.2 µg/m3 for determining whether SO2 or NOx
emissions in a state make a significant contribution to PM2.5
nonattainment in another state.  Of the 37 states analyzed, 28 states
and the District of Columbia were found to make a significant
contribution to PM2.5 nonattainment.  Maine was found to not make a
significant contribution to downwind PM2.5 nonattainment, since it had
less than a 0.05 µg/m3 maximum impact on any downwind site.  

II.  Prevention of Significant Deterioration and Nonattainment New
Source Review

Section 110(a)(2)(D)(i)(II) also requires States to submit SIPS that
prohibit “…any source or other type of emission activity within the
State from emitting any air pollutant in amounts which will- interfere
with measures required to be included in the applicable implementation
plan for any other State … to prevent significant deterioration of air
quality…”

EPA regulations require each SIP to include a preconstruction review
program for major sources to satisfy the requirements of section
110(a)(2)(D)(i).  In nonattainment areas, the preconstruction review
program is known as Nonattainment New Source Review (NSR) and in
attainment areas, the preconstruction review process is part of the
Prevention of Significant Deterioration (PSD) program.  These programs
require preconstruction permits to protect the air quality within each
state, and also serve to prohibit construction of new major sources and
major modifications at existing major sources from contributing to
nonattainment in adjacent states.  The PSD permitting program is also
the primary measure that each SIP must include to prevent significant
deterioration of air quality in accordance with Title I, Part C and
section 110(a)(2)(D)(ii) of the CAA. 

Since all areas of the country are currently subject to some form of
preconstruction permitting program for ozone and PM2.5, it is not
necessary for States to make a SIP submission containing rule changes or
modeling demonstrations in order to address the section 110(a)(2)(D)(ii)
requirements for the 8-hour ozone and PM2.5 NAAQS.  Since the air
quality demonstrations required for issuance of a PSD and NSR permit
must be made for all areas that are potentially impacted by emissions
from a proposed source or modification requiring a permit,
implementation of  PSD and NSR permitting program in each state serves
to prevent significant deterioration and largely satisfies the
requirements of section110(a)(2)(D)(i)(II) of the CAA.  

Maine’s PSD regulations require the owner of any proposed new major
source or major modification to demonstrate that any increased emissions
from a proposed facility or expansion would not significantly
deteriorate air quality, regardless of where these emissions may travel.
 Proposed facilities subject to Maine’s PSD licensing requirements
must therefore assess PSD increment consumption in Maine as well as
adjacent or downwind states.  

The federal visibility regulations promulgated in December 1980 require
consideration of the effects of new sources on the visibility values of
Federal Class I areas.  Chapter 115 of the Department’s regulations
requires owners and operators of all new major stationary sources or
major modifications to perform an additional impact analysis to assess
impacts on visibility in federal Class I areas.  In practice, this
provision requires a modeling demonstration that may consist of a Level
I or Level II visibility screening analysis, or a more refined
visibility modeling review that would involve the use of tools such as
the CALPUFF model.  These analyses require the source owner or operator
to demonstrate that operation of the source will have an insignificant
visibility impact on the applicable Class I area.  The Department works
closely with the appropriate federal land manager when reviewing these
analyses.  This provision of Maine’s NSR regulations essentially
prohibits the permitting of a major stationary source or major
modification that may significantly degrade visibility in a federal
Class I area.

The NSR program in Maine is implemented through the Chapter 100
Definitions Regulation which was approved into the SIP on October 15,
1996, the Chapter 113 Growth Offset Regulation which was approved into
the SIP on February 14, 1996, and the Chapter 115 Major and Minor Source
Air Emission License Regulations which were approved into the SIP by EPA
on February 14, 1996.  Although these rules have been amended several
times since being incorporated into the SIP, these revisions did not
change any of the major source permitting requirements, and the current
state regulations are consistent with the SIP-approved versions for the
purposes of implementing the New Source Review program.

On March 31, 2006, the Maine Department of Environmental Protection
submitted an equivalency demonstration documenting that Maine’s
current NSR program is identical to current Federal PSD and
nonattainment  NSR regulations with respect to newly constructed sources
and at least as stringent, or more stringent than current federal
regulations for modifications at existing major stationary sources.

Visibility Requirements

Section 110(a)(2)(D)(i)(II) also contains a requirement for all States
to submit SIPs that contain adequate provisions prohibiting “…any
source or other type o f emission activity within the State from
emitting any air pollutant in amounts which will interfere with measures
required to be included in the applicable implementation plan for any
other State …to protect visibility.”

EPA adopted a phased approach to visibility protection, issuing
regulations addressing reasonably attributable visibility impairment in
1980, and regulations to address regional haze in 1999. 

 

In 1999, EPA found that all states contain sources whose emissions are
reasonably anticipated to contribute to regional haze in one or more
Class I areas.   As a result, states must submit SIPs containing
measures to address regional haze, including a long-term strategy to
address visibility impairment for each Class I area which may affected
by emissions from a state.  These SIPs are due no later than December
17, 2007.  As a result of the regional haze planning requirements, EPA
has made a finding that it is premature to determine whether a state’s
SIP for 8-hour ozone or PM2.5 contains adequate provisions to prohibit
emissions that interfere with measures in other States SIPs until these
Regional Haze SIPs are submitted and approved.  Maine’s Regional Haze
SIP will assess whether there is any interference with measures required
to be included in the applicable implementation plan for any other state
to prevent significant deterioration of air quality or to protect
visibility.

EPA issued its notification as part of an action required under a
Consent Decree resolving the case entitled “Environmental Defense, et
al. v. Johnson,” No.1:05CV00493(D.D.C). See: “Findings of Failure to
Submit Section 110 State Implementation Plans for Interstate Transport
for the National Ambient Air Quality Standards for 8-Hour Ozone and PM
2.5,” 70 FR 21,147 (April 25, 2005). 

Federal Register  Volume 70, Number 91,  Pages  25162 through -25405
(May 12, 2005) 

 Section 182(f) of the CAA along with other sections of the CAA requires
states in the Ozone Transport Region to adopt reasonably available
control technology (RACT) rules for major stationary sources of NOx, and
to provide for nonattainment area new source review for new sources and
modifications that meet or exceed the major source threshold for NOx. 
The areas included in the section 182(f) “NOx Waiver” are therefore
not subject to RACT, along with new source review offset and lowest
achievable emission rate control requirements.

 Maine’s NOx exemption request became effective on March 6, 2006. 

 Zulu or UTC time.

 “Technical Support Document for the Final Clean Air Interstate Rule,
Air Quality Modeling”, U.S. EPA Office of Air Quality Planning and
Standards, March 2005. 

 45 FR 8009

 61 FR 53639

 61 FR 5694

 61 FR 5694

 Reasonably attributable visibility impairment is visibility impairment
that is caused by the emissions of air pollutants from one, or a small
number of sources.

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