1 Enclosure

New Hampshire Area Designations For the

2010 SO 2 Primary National Ambient Air Quality Standard

Summary

Pursuant to section 107(d) of the Clean Air Act (CAA), EPA must designate areas as either

“nonattainment

, ” “attainment

, ” or “unclassifiable” for the 2010 1

- hour sulfur dioxide (SO 2 ) primary national ambient air quality standard (NAAQS). The CAA defines a nonattainment area as one that does not meet the NAAQS or that contributes to poor air quality in a nearby area that does not meet the NAAQS. Table 1 below identifies the portions of counties in New Hampshire in the Central New Hampshire area EPA is initially designat ing “nonattainment” based on

monitored violations

. EPA is not yet prepared to designate other areas in New Hampshire.

Table 1 . Nonattainment Designation for New Hampshire

Area New Hampshire

Recommend ed Designation of

Areas/ Counties EPA’s Designat ion of

Areas/ Counties

Central New Hampshire Hillsborough County (partial)

Goffstown

Merrimack County (partial)

Allenstown

Bow

Chichester

Concord

Dunbarton Epsom

Hooksett

Loudon

Pembroke

Pittsfield Rockingham County (partial)

Candia

Deerfield

Northwood Nonattainment

Nonattainment

Nonattainment Nonattainment

Nonattainment

Nonattainment

Background

On June 2, 2010, EPA revised the primary SO 2 NAAQS (75 FR 35520, June 22, 2010) by establishing a new 1

- hour standard at a level of 75 parts per billion (ppb) which is met at an2

ambient air quality monitoring site when the 3

- year average of the annual 99 th percentile of the daily maximum 1

- hour average concentration s at is less than or equal to 75 ppb , as determined in accordance with Appendix T of 40 CFR part 50. 40 CFR 50.17(a)

- (b). EPA has determined this is the level necessary to provide protection of public health with an adequate margin of safety, especially for children, the elderly and those with asthma. These groups are particularly susceptible to the health effects associated with breathing SO 2 . The Agency is revoking the two prior primary stan dards of 140 ppb evaluated over 24

- hours, and 30 ppb evaluated over an entire year because the standards will not add additional public health protection given a 1

- hour standard at 75 ppb. Accordingly, EPA is not designating areas in this process on the b asis of either of these two prior primary standards. Similarly, the secondary standard for SO 2 has not been revised, so EPA is not designating areas in this process on the basis of the secondary

standard.

EPA’s SO 2 Designation Approach

Section 107(d) of the CAA requires that not later than 1 year after promulgation of a new or revised NAAQS, state Governors may submit their recommendations for designations and boundaries to EPA. This deadline was in June, 2011. Section 107(d) also requires EPA to provi de a notification to states of no less than 120

- days prior to promulgating an initial area designation that is a modification of a state’s recommendation. EPA has reviewed the State’s recommendations and has notified the State Commissioner through a lett er signed by the Regional Administrator of any intended modifications. While language in section 107 specifically addresses states, we followed the same process for the tribal government s , pursuant to section 301(d) of the CAA and Tribal Authority Rule (4 0 CFR Part 49). Therefore, we are designating tribal areas, in consultation with the tribal government s , on the same schedule as state designations. New Hampshire does not have any tribal governments affected by this designation. If a s tate or tribal go vernment does not submit designation recommendations, EPA will promulgate the designations that it deems appropriate. If a state or tribal government disagrees with EPA’s intended area designations, it has an opportunity to demonstrate why any proposed mo dification is inappropriate.

Designations guidance was issued by EPA through a March 24, 2011

, memorandum from Stephen D. Page, Director, U.S. EPA, Office of Air Quality Planning and Standards, to Air Division Directors, U.S. EPA Regions I

- X. This memorandum identifies factors EPA intends to evaluate in determining boundaries for areas designated nonattainment. These 5 factors include: 1) a ir quality data; 2) e missions and emissions

- related data (location of sources and potential

contribution to ambient SO 2 concentrations); 3) m eteorology (weather/transport patterns); 4)

g eography

/topography (mou ntain ranges or other air basin boundaries); and 5) j urisdictional boundaries (e.g., counties, air districts, pre

- existing nonattainment areas, reservations, metropolitan planning organization), among any other information deemed relevant to establishing a ppropriate area designations and boundaries for the 1

- hour SO 2 NAAQS.

The March 24, 2011, memo recommended that area boundaries be defaulted to the county boundary unless additional provided information justifies a larger or smaller boundary than that

of the county. EPA believes it is appropriate to evaluate each potential area on a case

- by

- case basis, and to recognize that area

- specific analyses conducted by states, tribal governments and/or EPA may support a different boundary than a default county boun dary.3

In this TSD, EPA discusses its review and technical analysis of the recommendations submitted by the state for designations of the 1

- hour SO 2 standard and any modifications from these

recommendations.

Definition of important terms used in this docu ment:

1) Designated “nonattainment” area

– an area which EPA has determined, based on a state recommendation and/or on the technical analysis included in this document, has violated the

2010 SO 2 NAAQS, based on the most recent three years of air quality m onitoring data, or contributes to a violation in a nearby area.

2 ) Recommended nonattainment area

– an area that a s tate or tribal government has

recommended to EPA to be designated as nonattainment.

3 ) Violating monitor

– an ambient air monitor meeting all methods, quality assurance and citing criteria and requirements whose valid design value exceeds 75 ppb, as described in Appendix T of 40 CFR part 50.

4 ) 2010 SO 2 NAAQS

- 75 ppb, national ambient air quality standard for SO 2 promulgated in

201 0. Based on the 3

- year average of the 99 th percentile of the annual distribution of daily

maximum 1

- hour average concentrations

.

5 ) Design Value

– a statistic that describes the air quality status of a given area relative to the level of the NAAQS.

Non attainment Designations

Technical A nalysis for Central New Hampshire Nonattainment Area

Introduction

Th is technical analysis for the Central New Hampshire n onattainment a rea analyzes the county

with a monitor that violate s the 2010 SO 2 NAAQS based on 2009

- 2011 data, and evaluates the

risk of nearby cities and towns in different counties being above the standard. EPA has

evaluated this area based on the weight of evidence of the factors recommended in the March 24,

2011 issued EPA guidance

.

Figure 2 is a map of New Hampshire showing the location s of air quality monitor s in the area, and the counties surrounding any violating air quality monitors

. Figure 3 shows the cities and towns included in the Central New Hampshire n onattainment area.

Figure 1. Central New Hampshire Nonattainment Area

In July 2011

, Go vernor Lynch r ecommended that certain partial counties be designated as

“nonattainment” for the 2010 SO 2 NAAQS b ased on monitored air quality data from 2008

- 2010 and through a n analysis that included air quality data, emissions data, geography and topography, meteorology and transport patterns, and jurisdictional boundaries.4

Based on EPA's technical analysis described below, EPA is initially designat ing 14 cities and

towns in 3 different counties in New Hampshire a s nonattainment for the 2 010 SO 2 NAAQS as part of the Central New Hampshire nonattainment area

, based upon currently available

information

. These cities and towns ar e listed above in Table 1

. EPA is not yet prepared to designate other areas in New Hampshire.

Detailed Assessment

Air Q uality D ata

This factor considers the SO 2 air quality monitoring data, including the design values (in ppb )

calculated for all air quality monitors in the Central New Hampshire area and the surrounding

area based on data for the 200 9

- 20 1 1 period

.

Governor Lynch ’s recommendation was based on data from Federal Reference Method monitors

located in the state. See letter from Governor Lynch to Curt Spalding, E PA Region 1 Administrator, dated July 6, 2011.

The 2011 SO 2 NAAQS design values for counties in the Central New Hampshire and surrounding area are shown in Table 2

.

Table 2 . Air Quality Data in New Hampshire

County Monitor

Name Monitor Air

Quality System ID Monitor

Location SO 2 Design

Value,

200 9

- 20 11 09 (ppb)

Merrimack Pembroke

Exchange St 330131006 Pembroke 221

Hillsborough Manchester 330110020 Manchester 56 Rockingham Portsmouth 330150014 Portsmouth 41

Monitor in Bold ha s the highest 200 9

- 201 1 design value in the state

.

Merrimack County shows a violation of the 2010 SO 2 NAAQS

. Therefore

, some area in this

county and possibly additional areas in surrounding counties must be designated nonattainment

. The absence of a violating monitor alone is not a sufficient reason to eliminate nearby counties

as candidates for inclusion in a nonattainment status. E ach area has been evaluated based on the weight of evidence of the five factors and other relevant information.

The largest emitter of SO 2 emissions in New Hampshire is within a few miles of the Pembroke Exchange St monitor. This emitter is identified as Public Service of New Hampshire’s

Merrimack Station in Bow , New Hampshire . Wind frequency diagrams based on meteorological data gathe red at Merrimack St ation during 1994 and wind frequency data from the years 2000

- 2004 obtained at a nearby airport (Concord) shows the prevailing wind direction is from the northwest. Merrimack Station is northwest of the Pembroke Exchange St monitor.

Emissions and Emissions

- Related Data5

Evidence of SO 2 emissions sources in the vicinity of a violating monitor is an important factor for determining whether a nearby area is contributing to a monitored violation. For this factor, EPA evaluated county level emission data for SO 2 and any growth in SO 2 emitting activities since the date represented by the emissions data

.

Emissions

EPA recognizes that there may be important new information on emissions levels for th e period after 2008, and would consider more recent information if available. New Hampshire did not provide updated emissions information, therefore EPA relied on the 2008 N ational E missions

I nventory (NEI) emissions data ( 0 8 NEI V 3 )

.

Table 3 shows total emissions of SO 2 (given in tons per year) for violating and potentially contributing counties in and around the Central New Hampshire nonattainment area , including sources emitting greater than 100 tons per year of SO 2 according to the 2008 NEI. The count ies

that are partially included in the Central New Hampshire nonattainment area for the 2010 SO 2 NAAQS are shown in bold

.

Table 3 : Sources with SO 2 greater than 100 tons in 2008

County City/Town Facility Name SO 2 Emissions (2008 in tpy) Total County

SO 2 Emissions (tons per year)

Merrimack Bow PSNH

- Merrimack Station 31,307.4 99% Rockingham Portsmouth PSNH

- Schiller Station 4,988.4 88% Rockingham Newington PSNH

- Newington Station 590.0 10%

Strafford Rochester Turnkey Recycling &

Environmental Enterp 150.2 67%

Hillsborough Bennington Monadnock Paper Mills,

Inc 132.9 58%

Emission Controls

The emissio ns data used by EPA in this technical analysis and provided in Table 3 represent
emiss ion levels taking into account any control strategies implemente d on the listed stationary

sources up to and including the year 2008

. EPA is aware SO 2 controls have been installed at Merrimack Station. The facility is required by state law to have the wet scrubber operational no later than July 1, 2013. Once fully operational, the wet scrubber should significantly reduce SO 2 emissions from Merrimack Station.

Meteorology (weather/transport patterns)

Evidence of source

- receptor relationshi ps between specific emission sources and high SO 2 values at violating monitors is another important factor in determining the appropriate contributing areas and the appropriate extent of the nonattainment area boundary. For this factor,

EPA considered rec ent hourly or sub

- hourly meteorological data from the site nearest to the violating monitor to determine which wind vectors were associated with 1

- hour SO 2 exceedances. For the designated nonattainment area

, the meteorological data used in this6

analysis i s based on data at the Pembroke monitor. The monitor is approximately 0.75 miles

southeast of PSNH

- Merrimack Station.

Figure 1 shows a map of the monitor location with meteorological data and large SO 2 sources in

the area. Figure 4 shows the wind direct ion associated with exceed a nces at the Pembroke monitor during 2009

- 2011 . Most of the exceedances occur when the wind is from the n orthwest. As shown if Figure 1 , a wind from out of the n orthwest would carry the plume from PSNH

Merrimack over the Pembrok e monitor.

On July 6, 2011, New Hampshire submitted its analysis of wind patterns depicting SO 2

e missions from Merrimack Station hav ing a large effect on the violating monitor. The state submitted two wind roses, one using meteorological data gathered at Merrimack Station in 1994 and five years (2000

- 2004) worth of meteorological data from a nearby airport (Concord Municipal). Both wind roses show the wind is predominantly from the n orthwest. The

Pembroke monitor is southeast of Merrimack Station.

EPA compared the wind roses submitted by New Hampshire and meteorological data obtained from the Concord, NH Airport for the period from 200 6 to 2011. The distribution of wind direction is consistent with that shown in the wind rose provided by New Hampshire.

The wind roses also demonstrate the low probability that emissions from other sources with SO 2 emissions above 100 tpy will contribut e to the Pembroke monitor’s design value in the Central New Hampshire nonattainment area. As shown in Figure 1 , three of these sources are east of the nonattainment area and at least 10 miles away. The other source is 20 miles west of the

nonattainment a rea. Given that the dominant wind direction is from the north w e st, the emissions

from the three facilities east of the nonattainment area will have more effect on the Portsmouth

monitor than on the Pembroke monitor

, and the Portsmouth monitor’s design val ue is less than

the standard.

Geography/topography (mountain ranges or other air basin boundaries)

Merrimack Station and the Pembroke monitor are located in a river valley surrounded by rolling

hills which reach 1000 feet above sea level. These hills are approximately 10 miles from Merrimack Station. Coupled with stable plume heights of 800 and 1000 feet from the two coal

fired units at Merrimack Station, New Hampshire used the terrain data to determine the

boundaries for the Central New Hampshire non attainment area. EPA concurs with the state’s findings.

Jurisdictional boundaries

As explained above, the Central New Hampshire nonattainment area is based on city and town

boundaries instead of entire counties and does not limit the nonattainment area to Merrimack County where the violating monitor is located.

Other Relevant Information

EPA did not receive additional information relevant to establishing a nonattainment boundary for

this area.7

Conclusion

After considering the factors described above, EPA find s that it is appropriate to include the

cities and towns i n Table 1 in the Central New Hampshire Area as the initial nonattainment area

for the 2010 SO 2 NAAQS

. Areas and sources that we are not yet prepared to conclude are contributing to the monitored violation at the Pembroke monitor are not included in this initial

nonattainment area. Such areas and sources will be further addressed in subsequent designations

.

The air quality monitor in Pembroke in the Central New Hampshire Area shows a violation of

the 20 10 SO 2 NAAQS, based on 200 9

- 201 1 air quality data. Based on the consideration of all the relevant and available information, as described above, EPA is designat ing the Central New Hampshire Area as nonattainment for the 20 10 SO 2 NAAQS. In a subsequent round of designations we will make final designations decisions for areas that are not currently included in the nonattainment area designation addressed in this TSD.8 Figure 1: Map of the Central New Hampshire nonattainment area including location of sources with emissions greater than 100 tpy (based on 2008 data from NEI) and ambient monitors.9 Figure 210 Figure 311 Figure 4