### STATE OF NEW HAMPSHIRE

STATE IMPLEMENTATION PLAN REVISION

CARBON MONOXIDE LIMITE D MAINTENANCE PLAN
for the
THE CITY OF MANCHESTER AN D THE CITY OF NASHUA
CARBON MONOXIDE MAINTENANCE AREAS

August 1, 2012

29 Haz en Drive
P.O Box 95 Concord, NH 03302-0095 www.des.nh.gov(Page intentionally left blank)

2Table of Contents

1 Introduction 4

2 Background 4

3 Limited Maintenance Plan Option 5

3.1 Attainment Emissions Inventory 6

3.2 Demonstration of Continued Attainment 8

3.3 Monitoring Network/Verification of Continued Attainment 10

3.4 Contingency Plan 12

3.5 Conformity Determination unde r Limited Maintenance Plans 13

4 Conclusion 15

5 Public Record & Comment 1 5

List of Tables Table 1 Winter Day CO Emissions for Hillsborough County, 2008 7 Table 2 CO Emissions for Hillsborough County, 1999 – 2008 8 Table 3 CO Emissions for New Hampshire, 1999 – 2008 8
Table 4 1 and 8-hour Design Values by year (Manchester & Nashua) 9
Table 5 1 and 8-hour 2 nd Highest Concentrations by y ear (Manchester & Nashua) 10 Table 6 Manchester CO Conformity Determination Projection 14 Table 7 Nashua CO Conformity De termination Projection 14

List of Figures Figure 1 Annual 1-hour 2 nd Highest Concentrations, (Manchester & Nashua) 10 Figure 2 Annual 8-hour 2 nd Highest Concentrations, (Manchester & Nashua) 10

Attachments
Attachment 1 Memorandum: “Limited Maintena nce Plan Option for Nonclassifiable CO Nonattainment Areas”; Joseph W. Paisie , Group Leader; Integrated Policy and Strategies Group; October 6, 1995 Attachment 2 Letter from Anne Arnold, EP A Air Quality Planning Unit: Air Quality Conformity: Statewide Transportation Improvement Program Amendment Number 1 (2011 – 2014 STIP ); to Kathleen O. Laffey; May 4, 2011 Attachment 3 Memorandum: Limited Maintenance Plan Option for Moderate PM 10 Nonattainment Areas; Lydia Wegman, Director; August 21, 2001
Attachment 4 Public Notice
Attachment 5 Proof of Publication

31. Introduction

The City of Manchester (Manch ester) and the City of Nas hua (Nashua) were designated
nonattainm ent by the U.S. Environmental Protection Agency (EPA) for carbon monoxide (CO) in 1980 (45 FR 24869 and 48 FR 29479, respectively ). The National Ambient Air Quality Standard (NAAQS) for CO is 9.0 parts per milli on (ppm) for an 8-hour average concentration and 35 ppm for a 1-hour concentration, not to be ex ceeded more than once per calendar year. In 1991, following passage of the Clean Air Act Am endments of 1990 (CAA), both cities were
classified “nonattainment” and “not classi fied” (56 FR 56694) although ambient monitoring showed NAAQS attainment had been achieved by that time. In February 1999, the State of New Hampshire submitted a formal CO redesign ation request as part of a CO Maintenance Plan for Manchester and Nashua and, effective January 29, 2001, EPA redesignated Manchester (65 FR 71078) and Nashua (65 FR 71078) from CO nonattainment, to CO attainment and approved New Hampsh ire’s CO Maintenance Plan.

Significant progress continues to be made in re ducing CO levels across the northeast including
the Manchester and Nashua areas. Dramatic reductions in CO levels from more fuel-efficient and cleaner operating vehicles, improved (OBD II) vehicle diagnostic equipment and cleaner burning fuels have cut CO emissions despite grow th. No violations of the CO NAAQS have
been recorded in the Manchester or Nashua areas since 1986 and the highest level of CO in either town in the last three years has been less than one half of the CO NAAQS. In addition to the downward trend shown by the monitoring da ta, the state has performed mobile source modeling and conformity analyses that indicat e winter CO emissions in Manchester and
Nashua will not reach even half of the CO Co nformity Budget as far into the future as 2035, well beyond the end of the maintenance plan.

Section 175A of the CAA requires a demonstration of continued attainment for at least ten years following EPA’s redesignation to attainment . Eight years after the redesignation, a state must submit a revised maintenance plan demons trating attainment for the ten years following the initial ten-year period. Although New Hampshire’s 1999 redesignation submittal was developed as a 20-year maintenan ce plan starting with the CO redesignation effective date, the New Hampshire Department of Environmenta l Services (DES) is submitting this State Implementation Plan (SIP) revision under the lim ited maintenance plan option as described in

an October 6, 1995, U.S. EPA guidance memora ndum (“Option Memo”) (Attachment 1). 1 This maintenance plan is being submitted to cover the second 10-year maintenance period starting January 29, 2011 and r unning through January 29 , 2021.

2. Background

The cities of Manchester and Nashua were designated CO nonattainm ent areas on April 11, 1980. Pursuant to Section 107(d)(1 )(C) of the CAA , the cities retained their designation of nonattainment for CO under the law even though that at the same time, the cities were

1 Memorandum: “Limited Maintenance Plan Option for Nonclassifiable CO Nonattainment Areas”; Joseph W. Paisie, Group Leader; Integrated Policy an d Strategies Group; October 6, 1995

4class ified as “not classified” since ambient monitoring data for the areas showed attainment of the CO NAAQS. In 1987, the State of New Hampshire initiated a basic CO Inspection/Maintenance (I/M) program in Nash ua and 11 surrounding towns. That program was designed to cease operating on January 1, 1995, at which time the State legislature allowed it to end. On February 1, 1999, DES submitted a re vision to the SIP to remove the Nashua I/M program. That program was replaced with contro ls consisting of the existing federal Tier 1
emission standards for new vehicles and the fe deral reformulated gasoline program. Because
the Manchester and Nashua area s were “not classified” under S ection 172, the CAA set forth the applicable requirements for nonattainment areas. The CAA required such an area to achieve the standard by November 15, 1995, and both cities have fulfilled this requirement.

On February 2, 1999, DES submitted a request to redesignate the cities of Manchester and
Nashua from CO nonattainment areas to CO atta inment areas. EPA approved the redesignation in November, 2000 (65 FR 71060). As part of the redesignation request, the State submitted a maintenance plan as required by 175A of the Cl ean Air Act, as amended in 1990. Elements of the Section 175A maintenance plan included a base year (1990 attainment year) emission inventory for CO, a demonstration of NAAQS maintenance, a plan to verify continued attainment, a contingency plan and an obligation to submit additional information acknowledging that the maintenance plan would remain in effect through the year 2020, as required by the CAA. The redesignation request established a Manchester motor vehicle emissions budget of 55.83 tons per day and a Na shua motor vehicles CO emission budget of 60.13 tons per day to be used in determining tr ansportation conformity in the Manchester and
Nashua areas.

On May 30, 2007, DES submitted a modification of the approved Nashua maintenance plan, discontinuing CO monitoring in Nashua, wh ich was approved by EPA on September 10, 2007 (72 FR 51564). Under that modification, DES agreed to continue to collect and review CO monitoring data from nearby Manchester. In th e event monitoring data showed CO levels in
Manchester reached 75% of the federal 1-hour or 8-hour NAAQS CO limit, an operating monitoring site in Nashua would be re-estab lished and DES would resume analyzing and reporting monitoring data. New Hampshire is no w proposing to disconti nue CO monitoring in Manchester and to rely instead on the monitoring station in nearby Londonderry.

3. Limited Maintenance Plan Option

On October 6, 1995, EPA published the Joseph W. Paisie Limited Maintenance Plan Option Memo. Based on that guidance, the core elem ents of a Limited Maintenance Plan are:

 Attainment inventory identifying the levels of emissions in an area;

 Maintenance Demonstration showing that design values do not exceed 85% of the NAAQS;

 Monitoring to verify continued eligibility;

5 Contingency Plan identifying m easures to be adopted in the event of a NAAQS violation; and

 Conformity Determination discussion.

3.1 Attainment Inventory

Regarding the attainment inventor y, the Option Memo notes that “[ t]he State should develop an attainment emissions inventory to identify a level of emissions in the area which is sufficient to attain the NAAQS. This inventory should be consistent with EPA’s most recent guidance on
emissions inventories for nonattainment areas available at the time and should represent emissions during the time period associated with the monitoring data sh owing attainment. The inventory should be based on actua l ‘typical winter day’ emissions of CO.” To this end, DES has prepared an attainment inventory for year 2008 for Hillsborough County which encompasses the cities of Manchester and Nashua.

The 2008 attainment inventory is subdivided into the following general emissions categories:

 Point Sources , which represent discrete facilities. These sources usually must meet
certain emission criteria to be included as point sources and genera lly represent larger
facilities.

 Area Sources , which represent facilities and activ ities too numerous and widespread to be inventoried individually but which collectively may account for significant
emissions.

 Non-Road Mobile Sources , including aircraft, locomotives , commercial marine vessels, construction vehicles, lawn & garden equipment, and other mobile vehicles and equipment that are not meant to be operated on roadways.

 On-Road Mobile Sources , including cars, trucks, buses, mo torcycles, and other vehicles that operate on public roadways.

The methodologies used in preparing the 2008 emissions estimates are summarized in the following paragraphs.

For point sources , affected facilities in New Hampshire are required to report their emissions on an annual basis. The reporting requirements for these facilities are provided under New Hampshire’s air regulations, its state air pe rmitting program, and the Air Emissions Reporting Requirement. Data su bmitted by these facilities are extensively cross-checked and quality assured by DES staff before eventual submittal to EPA. The point source data contained in New Hampshire’s 2008 attainment inventory orig inated from the quality-assured 2008 data from all reporting point sources in Hillsborough County.

6The methodologies used to estimate emissions for area source categories come primarily from EPA’s Emissions Inventory Improvement Program (EIIP). Calculations for many area source categories are based on variables such as populat ion, employment, and fuel consumption data. Descriptions of the methodologies for specific area source categories can be found in EIIP Volume 3, Area Sources , which is available at EPA’s Clearinghouse for Inventories and
Emissions Factors website at http://www.epa.gov/ttn/chief/eiip/techreport/volume03/index.html

. Seasonal adjustment factors from Table 1.4-3 of EIIP Volume III were used to derive winter season day estimates for the applicable s ource categories (e.g. residential heating).

For the non-road mobile category, DES used EPA’s NON ROAD2008a model to estimate 2008 emissions for those equipment types that are included in the model. The NONROAD model was run for a winter season day. For co mmercial aircraft a nd airport ground service equipment, the Federal Aviation Agency’s (F AA’s) Emissions & Dispersion Modeling System (EDMS) was used. Standardized methodologies and references were employed for equipment types not included in the ED MS or NONROAD models (e.g. , locomotives and commercial marine vessels).

For on-road mobile sources, DES used MOVES2010a with VMT and other road related data provided by the relevant metropolitan planning organizations (MPOs) as well as vehicle population data obtained from th e New Hampshire Department of Safety, Division of Motor
Vehicles.

Estimated winter day CO emissions for the 2008 attainment inventory are shown in Table 1.

Table 1 - Winter Day CO Emissions for Hillsborough County, 2008

Category CO emissions (tons per winter day)
Point 0.6*
Area 37.1
Non-Road Mobile 40.0
On-Road Mobile 165
Total 242.7 *Estimated tons per average day On-Road Mobile emissions generated using MOVES2010a

Tables 2 and 3 illustrate annual CO emissions in the Manchester and Nashua area (Hillsborough County) and statewide. As Ta ble 2 demonstrates, the total 2008 Hillsborough County emissions from all sources are estimate d to be 77,311 tons with all mobile sources estimated to contribute 40,576 tons or 52% of the total.

7Table 2 - CO Emissions for Hillsb orough County, 1999 – 2008

CO emissions (tons per year)
Category 1999 2002 2005 2008

Point 184 143 191 92

Area 12,822 12,864 13,210 13,384

Non-Road Mobile 32,162 29,216 26,776 23,259

On-Road Mobile 92,831 58,379 58,666 40,576

Total 137,999 100,602 98,841 77,311

Sources of Data 1999 and 2002: National Emissions Inventory data from EPA's Air Data website. 2005: 2005 National Emissions Inventory, Version 2 downloaded from EPA's CHIEF website. 2008: 2008 National Emissions Inventory, Version 1.5 downloaded from EPA's EIS Gateway.

Table 3 - CO Emissions for New Hampshire, 1999 - 2008

CO emissions (tons per year) Category 1999 2002 2005 2008

Point 4,923 2,724 4,754 3,357

Area 78,133 74,099 73,706 47,798

Non-Road Mobile 123,530 124,801 119,322 104,887

On-Road Mobile 345,413 294,533 236,990 174,154

Total 552,000 496,157 434,772 330,196

Sources of Data 1999 and 2002: National Emissions Inventory data from EPA's Air Data website. 2005: 2005 National Emissions Inventory, Version 2 downloaded from EPA's CHIEF website. 2008: 2008 National Emissions Inventory, Version 1.5 downloaded from EPA's EIS Gateway.

From 1999 to 2008, CO mobile source emissions declined by 49% in Hillsborough County and by 22%, statewide. Monitored levels of CO have continued to decrease over the last
decade and the modeled emissions of CO from on-road sources mirror this downward trend. The availability of cleaner cars through the Federal Motor Vehicle Control Program, together with the addition of local trans portation controls such as New Hampshire’s Inspection & Maintenance Progr am, including an annual On-B oard Diagnostics inspection,
have resulted in decreased emissions and, hence, lower CO concentrations.

3.2. Demonstration of Continued Attainment

According to the Option Memo, “[t]he maintenance demonstration requirement is considered to be satisfied if the monitoring data show that the area is meeting the air quality criteria for limited maintenance areas (7.65 ppm or 85% of the CO NAAQS) . There is no requirement to project emissions over the ma intenance period. EPA believes if the area

8begins th e maintenance period at or below 85 percent of exceedance levels, the air quality along with the continued applicability of PSD requirements, any control measures already in the SIP, and Federal measures, should provi de adequate assurance of maintenance over the initial 10-year maintenance period.

When EPA approves a limited maintenance pl an, EPA is concluding that an emissions budget may be treated as essentially not cons training for the length of the maintenance period because it is unreasonable to expect th at such an area will experience so much growth in that period that a violation of the CO NAAQS would result.” DES interprets this to mean that such an area is no longer requi red to demonstrate conformity to a CO motor vehicle emissions budget.

To qualify for the limited maintenance plan op tion, the CO Design Value for the area must be at or below 7.65 ppm (85% of the NAAQS 8-hour level of 9 ppm), based on at least 8 consecutive quarters (2 years) of data used to demonstrate a ttainment. Observation of the second highest 8-hour concentration is also an indicator of the area’s proximity to violating
the standard.

2000 to 2010 1-hour and 8-hour Design Values and 1-hour and 8-hour second highest CO
concentrations for Manchester and Nashua ar e summarized in Tables 4 and 5. The annual 1-hour and 8-hour second highest concentrations are represen ted graphically in Figures 1 and 2. In all cases, the design values and s econd highest concentrati ons are significantly less than the 7.65 ppm threshold specified in EPA guidance, thus making each area eligible for the limited maintenance plan option.

Table 4 - 1-hour and 8-hour Design Values by year (Manchester and Nashua)*

Manchester Nashua
Bridge St Pearl St Main St

Year 1-hr 8-hr 1-hr 8-hr 1-hr 8-hr

2 0 0 0

2001 7.1 3.6 8 4.1

2002 3.7 2 6.5 4

2003 4.8 3.4 6.2 4

2004 4.8 3.4 6.2 4

2005 2.8 1.8 6.1 3.2

2006 8.1 3 9.1 3.2

2007 8.1 3 9.1 2.4

2008 6 3.5

2009 6 3.5

2010 3.2 2.4

* Note: Because CO Design Values are based on the higher value between one year and the previous year, there is no design value for 2000, the first year in which data was recorded.

9Table 5 – 1-hour and 8-hour 2 nd high concentrations by year (Manchester and Nashua)

Manchester Nashua

Bridge St Pearl St Main St

Year 1-hr 8-hr 1-hr 8-hr 1-hr 8-hr

2000 7.1 3.6 8 4.1

2001 4.6 3.1 6.5 4

2002 3.7 2 5.9 3.7

2003 4.8 3.4 6.2 4

2004 2.2 1.4 4.3 2.8

2005 2.8 1.8 6.1 3.2

2006 8.1 3 9.1 2.4

2007 2.6 1.8 3.7 2.2

2008 6 3.5

2009 3.2 2

2010 3.1 2.4

Figure 1 - Annual 1-Hour 2nd Highest
Concentrations - 2000 - 2010

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 Figure 2 - Annual 8-Hour 2nd Highest
Concentrations - 2000 - 2010

0 1 2 3 4 5 6 7 8 9 10

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010Parts per Million Manchester

Nashua

NAAQS

0 5 10 15 20 25 30 35 40

2000Parts per Million Manchester

Nashua

NAAQS

3.3. Monitoring Network/Verifica tion of Continued Attainment

W ith respect to monitoring, the Option Memo reads: “To verify the attainment status of the area over the maintenance period, the maintena nce plan should contain provisions for continued operation of an appropriate, EPA- approved air quality monitoring network, in accordance with 40 CFR 58. This is particul arly important for areas using a limited maintenance plan, because there wi11 be no cap on emissions.”

10As part of this Lim ited CO Maintenance Pl an, New Hampshire is proposing to discontinue monitoring CO at its Manchester site. In lieu of operating that site, DES plans to track CO using data collected from the following sources:

1. CO monitoring will continue year-round at the Londonderry Moose Hill station in Londonderry. The Londonderry Moose Hill Station came online on January 1, 2011
as an NCore 2 superstation measuring a wide va riety of pollutants. DES worked closely with EPA to carefully select this site due to its central proximity to Manchester and Nashua. The Londonderry station measures PM 2.5 (continuous and filter-based) Nitrogen Oxides, Ozone, Sulfur Dioxide (trace) and Carbon Monoxide (trace) as well as wind speed, wind direction and relative humidity.

2. New Hampshire’s emissions inventory tabulat es CO emissions from point, area and mobile sources. As demonstrated earlier (see Table 1), New Hampshire has been in
attainment for CO since 1999 and the vast preponderance of NH CO emissions are from mobile sources. New Hampshire will continue to provide a multi-source inventory every 3 years that will be used for identifying CO mobile source
emissions trends within the state.

A review of over 8,600 hourly samples taken since the Londonderry station came online shows 1-hour CO levels varying from 0.0 ppm to a high of 2.65 ppm at 2:00 AM on January 11, 2011. Because design values ar e based on two years of data, and the Londonderry station has been operating for onl y 15 months, it is not yet possible to
calculate the maximum and second maximum 8-hour design values over two years as protocol requires. Using 15 months of values averaged over 8-hour non-overlappping periods, the maximum 8-hour highest and 2 nd highest CO Design Values, are 1.77 and 1.23 ppm, respectively. Similar to the Nashua and Manchester station results, these levels are well below the CO NAAQS. The relatively short period of Londonderry station operation, however, makes it impossible to determine if there is a general downward trend in CO levels, as demonstrated by 10 years of data from the Nashua and Ma nchester stations.

Should the present downward trend of mobile source CO emissions reverse, and in the event the second-highest CO concentration in any calendar year m onitored in Londonderry reaches 50 percent of either the federal 1-hour or 8-hour NAAQS fo r CO, New Hampshire will, within six months, reestablish a CO mon itoring site in Manchester consistent with EPA siting criteria and resume analyzing and reporting those data. New Hampshire commits to implement its contingency program in Nashua in the event that a CO violation is monitored at the re-established Nashua monitoring site at any time during the

2 One of the most significant changes in the EPA air monitoring regulations was the requirement to establish National Core (NCore) multi-pollutant monitoring stations. These stations will provide data on several pollutants at lower detection limits and replace the National Air Monito ring Station (NAMS) networ ks that have existed for several years.

11m aintenance period. If the Manchester CO mon itor measures a violati on of the either the federal 1-hour or 8-hour NAAQS for CO, con tingency measures will be implemented in Nashua as well, until a re-established CO mon itor in Nashua shows that the area is in
attainment of the CO standard.

3.4. Contingency Plan

According to the Option Memo, “Section 175A of the CAA requires that a maintenance plan include contingency provisions, as necessa ry, to promptly correct any violation of the NAAQS that occurs after rede signation of the area. These contingency measures do not have to be fully adopted at the time of rede signation. However, the contingency plan is considered to be an enforceable part of th e SIP and should ensure that the contingency measures are adopted expeditiously once they are triggered by a specified event. The contingency plan should identify the measur es to be promptly adopted and provide a schedule and procedure for adoption and implem entation of the measures. The State should also identify specific indicators, or triggers , that will be used to determine when the contingency measures need to be implemen ted. While an exceedance of the NAAQS is an acceptable trigger, States may wish to choose a pre-exceedance action level as a trigger. By taking early action, a State may be able to prevent any actual viol ation of the NAAQS and, therefore, eliminate any need on the part of EPA to redesignate an area back to
nonattainment.”

DES believes that specific contin gency measures are not needed at the present time, since
the current CO levels are so far below th e NAAQS, and since emissions from mobile sources, the dominant source of CO in the State and Manche ster and Nashua regions, are decreasing in spite of incr easing population. As mentione d, previously implemented contingency measures and emi ssions reductions strategies have proven successful, and these will be continued through the maintenance period. These include:

 Vehicle Inspection/Maintenance (I/M) - Although federal regulations (40 CFR 51.350) required New Hampshire to imple ment an I/M program with tailpipe emissions testing, New Hampshire’s program of anti-tampering inspections for pre1996 vehicles less than 20 years old and an OBD II inspection on all model years 1996 and newer has provided superior environmental benefits to expensive and onerous tailpipe testing. New Hampsh ire will continue its EPA-approved OBD II program as a SIP strengthening measure.

 Vehicle Miles Traveled re ductions – Reducing vehicle use and traffic congestion, and their associated emissions, are key st ate and local transportation objectives. DES will continue to work with DOT and regional MPOs to identify effective congestion and emission reduction project a nd programs such as such as traffic signal coordination, increased mass transit, RideShare, anti-idling and other traffic management strategies.

12 Em issions reductions – New Hampshire con tinues to enjoy the benefits of the Federal Clean Fuel Programs that resulted in reduced CO emissions. In keeping
with President Obama’s 2009 national fuel economy and emissions policy, DES and local MPOs are actively promoting low emi ssions vehicles and emissions reductions strategies such as anti-idli ng programs and park & ride lot construction as part of their long range transportation plans.

Because New Hampshire proposes to discontin ue monitoring CO in Manchester, it will adopt a more stringent conti ngency threshold or “trigger” than indicated in the 2007 SIP revision. As indicated in Section 3.3 above, New Hampshire will monitor CO levels using the Londonderry Moose Hill station and emissions inventories. In the event the secondhighest CO concentration in any calendar year monitored in Londonderry reaches 50 percent of the federal 1-hour or 8-hour NAAQS for CO, New Hampshire will, within six months of recording such concentrations, rees tablish the CO monitoring site in Manchester consistent with EPA siting criteria, and resu me analyzing and repor ting those data. New Hampshire commits to implement a contingency program in Nashua in the event that a CO
violation is monitored at the re-established Nashua monitori ng site at any time during the maintenance period. If the Manchester CO mon itor measures a violati on of the either the federal 1-hour or 8-hour NAAQS for CO, con tingency measures will be implemented in Nashua as well, until a re-established CO m onitor in Nashua shows that the area is in
attainment of the CO standard.

3.5. Conformity Determination under Limited Maintenance Plans

In discussing conformity, the Option Memo r eads: “The transportation conformity rule ( Determining Conformity of Federal Actions to State or Federal Implementation Plans ; 40 CFR 93; amended 1998) and the general conformity rule ( Requirements for Preparation, Adoption, and Submittal of Implementation Plans; 40 CFR 51; adopted 1994) apply to
nonattainment areas and maintenance areas operating under maintenance plans. Under either rule, one means of demonstrating conform ity of Federal actions is to indicate that expected emissions from planned actions are consistent with the emissions budgets for the area. Emissions budgets in limited maintenance pl an areas may be treate d as essentially not constraining for the length of the initial maintenance period because it is unreasonable to expect that such an area will experience so mu ch growth in that period that a violation of the CO NAAQS would result. In other words, EPA would be concluding that emissions need not be capped for the maintenance peri od. Therefore, in areas with approved limited maintenance plans, Federal actions requiring conformity determinations under the transportation conformity rule could be consid ered to satisfy the ‘ budget test’ required in 40 CFR 93.118, 93.119, and 93.120 of the rule. Similarl y, in these areas, Federal actions subject to the general conformity rule could be consid ered to satisfy the ‘budget test’ specified in section 93.158 (a) (5) (i) (A) of the rule.” As this is guidance, final and binding determinations regarding the eligibility of ar eas for the limited maintenance plan option will only be made in the context of notice and comment rulemaking actions regarding specific redesignation requests.

13In recent confor mity determinations (see attachment 2: May 4, 2011 letter to FHWA Administrator Ms. Kathleen O. Laffey from EPA Air Quality Planni ng Unit Manager Anne E. Arnold) the Southern NH MPO and the Nashua MPO have demonstrated that transportation conformity for the Manchester and Nashua CO attainment areas and the motor vehicle emissions for future years are consistent with the 2010 motor vehicles emissions budgets of 55.83 tons of CO per wint er day in Manchester and 60.13 tons of CO per day in Nashua (Tables 6 and 7). In fact, the projected CO emissions are less than half of the budgets in both areas.

Table 6 – Manchester CO Conformity Determination Projection

Carbon Monoxide Analysis Summary for the City of Manchester

Year CO tons/day (winter) CO Budget (tons/day)

2012 28.80 55.83
2017 26.65 55.83
2026 26.38 55.83
2035 27.66 55.83

Table 7 – Nashua CO Conformity Determination Projection

Carbon Monoxide Analysis Summary for the Nashua
Year CO tons/day (winter) CO Budget (tons/day)
2012 28.73 60.13
2017 26.11 60.13
2026 25.51 60.13
2035 26.64 60.13

Consistent with Mr. Paisie’s and Ms. Ar nold’s memos, DES will use the Interagency Consultation (IAC) process to inform the New Hampshire Department of Transportation (NHDOT) and MPOs that, upon approval of the limited maintenance plans, CO emissions budgets will no longer be constraining for tran sportation conformity because of the low levels of emissions, continued CO reduc tions resulting from 2000 Maintenance Plan reduction measures implementation, and expected growth during the maintenance period.

EPA further discusses the implications of a Limited Maintenance Plan (LMP) on conformity requirements in an August 21, 2001 guidance memorandum to EPA Regional Air Directors (see attachment 3: Lydia Wegman memorandum; Limited Maintenance Plan Option for Moderate PM 10 Nonattainment Areas ). That memo reads in part, “Emissions Budgets in LMP areas may be treated as esse ntially not constraining for the length of the maintenance period because it is unreasonable to expect that an area satisfying the LMP criteria will experience so much growth during that period of time such that a violation of
the PM 10 NAAQS would result. While this policy doe s not exempt an area from the need to affirm conformity, it does allow the area to demonstrate conformity without undertaking certain requirements of these rules. For tr ansportation conformity purposes, EPA would be concluding that emissions in these areas need not be capped for the maintenance period, and, therefore, a regional emissions analysis would not be required.” As this guidance

1415 suggests, New Hampshire will still be subj ect to CAA requirements to ensure CO conformity in LMP areas, but MPOs will not be required to provide regional analyses as long as LMP conditions are met. However, this is not to say that MPOs no longer have responsibility for ensuring individual transpor tation projects do not cause or contribute to any new localized CO violations. As pe r 40 CFR 93.116, project sponsors will still be required to perform hot-spot analyses for FH WA/FTA projects to demonstrate no new local violations will be created as a result of the projects.

4. Conclusion

CO levels in the Nashua and Manchester ma intenance areas have remained under the CO
standard as a result of nationa l and local control strategies implemented. In fact, the current design value for both areas is less than half the st andard. The current design values in the areas
have remained below the standard since both areas were designated and are expected to continue to maintain compliance with the sta ndard. New Hampshire ha s verified that the emission controls adopted to maintain the standa rd continue to be permanent and enforceable, that there are no new significant sources of carbon monoxide or increases in background emissions and that the state has in place a pr ogram to identify sources of exceedance and address any violation through enforcement a nd implementation of a contingency plan.

This plan satisfies New Hampshire’s obligation under Section 175A(b) of the CAA to submit a plan for maintaining the national primary ambient air quality standard for CO for the next ten years beyond the current maintenance plan.

5. Public Record & Comment

In accordance with 40 CFR 51.102, public participation in this request was provided as follows:

Notice of availability of the complete documen t and a notice of opportuni ty for the public to submit written comments and request a public he aring were published on June 22, 2012, in the
U NION L EADER and posted on the DES website at http://des.nh.gov/organization/division s/air/tsb/tps/m sp/categories/hot.htm

.

The comment period closed at 4:00 PM on July 23, 2012. During that pe riod, a public hearing on the proposed plan was not requested. Th e only comments received on the proposed plan were from EPA by letter dated Ju ly 19, 2012. EPA stated that, in the unlikely event monitors
should ever measure a violation or concentratio ns such that the design value exceeds 85% of the CO NAAQS, a full maintenance plan must be developed. In addition, EPA noted that the
effective date of the CO re designation was January 29, 2001, th ereby establishing January 29, 2021 as the end of the 20-year maintenance period. The plan was revised to reflect this date.

A copy of the legal public notice can be found as Attachment 4 and a copy of proof of publication can be found as Attachment 5.

## ATTACHMENT 1

## ATTACHMENT 2

## ATTACHMENT 31 This memorandum is intended to provide EPA's preliminary views on how certain moderate PM10 nonattainment

areas may qualify to submit a maintenance plan that meets certain limited requirements. Since it represents only the Agency's preliminary thinking that is subject to modification, this guidance is not binding on States, Tribes, the public, or EPA. Issues concerning the applicability of the limited maintenance plan policy will be addressed in actions to redesignate moderate PM10 nonattainment areas under § 107 of the CAA. It is only when EPA promulgates redesignations applying this policy that those determinations will become binding on States, Tribes, the public, and EPA as a matter of law.

2 Moderate PM 10 areas that do not meet the applicability criteria of this policy, and all serious PM 10 nonattainment
areas, should submit maintenance plans that meet our guidance for submission of a full maintenance plan as described in the September 4, 1992 memorandum, “Procedures for Processing Requests to Redesignate Areas to Attainment,” from John Calcagni, former Director of the Office of Air Quality Planning and Standards (OAQPS) Air Quality management Division to the Regional Air Division Directors (hereafter known as the Calcagni Memo). MEMORANDUM

SUBJECT: Limited Maintenance Plan Option for Moderate PM 10 Nonattainment Areas

FROM: Lydia Wegman, Director

AQSSD (MD-15)

TO: Director, Office of Ecosystem Protection, Region I

Director, Division of Environmental Planning & Protection, Region II Director, Air Protection Division, Region III Director, Air, Pesticides & Toxics Management Division, Region IV Director, Air and Radiation Division, Region V Director, Air Pesticides & Toxics, Region VI Director, Air and Toxics Division, Regions VII, IX Director, Air Program, Region VIII Director, Office of Air Quality, Region X

I. What is a Limited Maintenance Plan?

This memorandum sets forth new guidance 1 on maintenance plan submissions for certain moderate particulate matter (PM 10 ) nonattainment areas seeking redesignation to attainment (see section IV for further details on qualifying for the policy). If the area meets the criteria listed in this policy the State may submit a maintenance plan at the time it is requesting redesignation that is more streamlined than would ordinarily be permitted. This new option is being termed a limited maintenance plan (LMP) 2

.

II. Why is there a need for a limited maintenance plan policy?2

3 Dr. Shao-Hang Chu's paper entitled "Critical Design Value and Its Applications" explains the CDV approach and is
included in its entirety in Attachment A. This paper has been accepted for publication and presentation at the 94th Air and Waste Management Association (A&WMA) Annual Conference in June 2001 in Orlando, Florida. Before the U.S. Court of Appeals for the District of Columbia handed down its decision vacating the 1997 PM 10 national ambient air quality standards (NAAQS)(see American Trucking Associations, et al. v. Environmental Protection Agency (EPA), 175 F.3d 1027 (D.C. Cir. 1999), we were prepared to make case-by-case determinations that would make the 1987 PM 10 NAAQS no longer applicable in any area meeting the standards. In taking actions to remove the applicability of the 1987 NAAQS, we would have removed, as well, the nonattainment designation and Clean Air Act (CAA) part D requirements from qualifying areas. As a result of the D.C. Circuit’s decision, for areas subject to the 1987 NAAQS, the only route to recognized attainment of the NAAQS and removal of nonattainment status and requirements is formal redesignation to attainment, including submittal of a maintenance plan. Since many areas have been meeting the PM 10 NAAQS for 5 years or more and have a low risk of future exceedances, we believe a policy that would allow both the States and EPA to redesignate speedily areas that are at little risk of PM 10 violations would be useful.

III. How did EPA develop the approach used in the LMP option?

The EPA has studied PM 10 air quality data information for the entire country over the past eleven years (1989-1999) and has determined that some moderate PM 10 nonattainment areas have had a history of low PM10 design values with very little inter-annual variation. When we looked at all the monitoring sites reporting data for those years, the data indicate that most of the average design values fall below 2 levels, 98 μg/m 3 for the 24-hr PM 10 NAAQS and 40 μg/m 3 for the annual PM 10 NAAQS. For most monitoring sites these levels are also below their individual site-specific critical design values (CDV). The CDV is an indicator of the likelihood of future violations of the NAAQS given the current average design value and its variability. The CDV is the highest average design value an area could have before it may experience a future exceedance of the NAAQS with a certain probability. A detailed explanation of the CDV is found in Attachment A 3 to this policy which, because of its length, is a separate document accompanying this memorandum.

We believe that the very small amount of variation between the peaks and means in most of the data indicates a very stable relationship that can be reasonably expected to continue in the future absent any significant changes in emissions. The period we assessed provides a fairly long historical record and the data could therefore be expected to have been affected by a full range of meteorological conditions over the period. Therefore, the amount of emissions should be the only variable that could affect the stability in the air quality data. We believe we can reliably make estimates about the future variability of PM 10 concentrations across the country based on our statistical analysis of this data record, especially in areas where the amount of emissions is not expected to change.

IV. How do I qualify for the LMP option ?3

4 The methods for calculating design values for PM 10 are presented in a document entitled the “PM 10 SIP Development
Guideline”, EPA-450/2-86-001, June 1987. The State should determine the most appropriate method to use from this Guideline in consultation with the appropriate EPA Regional office staff.

5 If the EPA determines that the meteorology was not representative during the most recent five-year period, we may
reject the State’s request to use the LMP option and request, instead, submission of a full maintenance demonstration. To qualify for the limited maintenance plan option, an area should meet the following applicability criteria. The area should be attaining the NAAQS and the average PM 10 design value 4 for the area, based upon the most recent 5 years of air quality data at all monitors in the area, should be at or below 40 μg/m 3 for the annual and 98 μg/m 3 for the 24-hr PM 10 NAAQS with no violations at any

monitor in the nonattainment area 5 . If an area cannot meet this test it may still be able to qualify for the LMP option if the average design values of the site are less than their respective site-specific CDV.

We believe it is appropriate to offer this second method of qualifying for the LMP because, based on the air quality data we have studied, we believe there are some monitoring sites with average design values above 40 μg/m 3 or 98 μg/m

3 , depending on the NAAQS in question, that have experienced little variability in the data over the years. When the CDV calculation was performed for these sites we discovered that their average design values are less than their CDVs, indicating that the areas have a very low probability (1 in 10) of exceeding the NAAQS in the future. We believe it is appropriate to provide these areas the opportunity to qualify for the LMP in this circumstance since the 40 μg/m

3 or 98 μg/m

3 criteria are based on a national analysis and don’t take into account each local

situation.

The final criterion is related to mobile source emissions. The area should expect only limited growth in on-road motor vehicle PM 10 emissions (including fugitive dust) and should have passed a motor vehicle regional emissions analysis test. It is important to consider the impact of future transportation growth in the LMP, since the level of PM-10 emissions (especially from fugitive dust) is related to the level of growth in vehicle miles traveled (VMT). Attachment B (below) should be used for making the motor vehicle regional emissions analysis demonstration.

If the State determines that the area in question meets the above criteria, it may select the LMP option for the first 10 year maintenance period. Any area that does not meet these criteria should plan to submit a full maintenance plan that is consistent with our guidance in the Calcagni Memo in order to be redesignated to attainment. If the LMP option is selected, the State should continue to meet the qualifying criteria until EPA has redesignated the area to attainment. If an area no longer qualifies for the LMP option because a change in air quality affects the average design values before the redesignation takes effect, the area will be expected to submit a full maintenance plan.

Once an area selects the LMP option and it is in effect, the State will be expected to recalculate the average design value for the area annually and determine if the criteria used to qualify for the LMP4

will still be met. If, after performing the annual recalculation of the area’s average design value in a given year, the State determines that the area no longer qualifies for the LMP, the State should take action to attempt to reduce PM 10 concentrations enough to requalify for the LMP. One possible approach the State could take is to implement a contingency measure or measures found in its SIP. If, in the next annual recalculation the State is able to re-qualify for the LMP, then the LMP will go back into effect. If the attempt to reduce PM 10 concentrations fails, or if it succeeds but in future years it becomes necessary again to address increasing PM 10 concentrations in the area, that area no longer qualifies for the LMP. We believe that repeated increases in PM 10 concentrations indicate that the initial conditions that govern air quality and that were relied on to determine the area’s qualification for the LMP have changed, and that maintenance of the NAAQS can no longer be assumed. Therefore, the LMP cannot be reinstated by further recalculations of the design values at this point. Once the LMP is determined to no longer be in effect, a full maintenance plan should be developed and submitted within

18 months of the determination.

Treatment of data used to calculate the design values.

Flagged Particulate Matter Data:

Three policies allow PM-10 data to be flagged for special consideration:

• Exceptional Events Policy (1986) for data affected by infrequent events such as industrial accidents or structural fires near a monitoring site;

• Natural Events Policy (1996) for data affected by wildfires, high winds, and volcanic and seismic activities, and;

• Interim Air Quality Policy on Wildland and Prescribed Fires for data affected by wildland fires that are managed to achieve resource

benefits.

We will treat data affected by these events consistently with these previouslyissued policies. We expect States to consider all data (unflagged and flagged) when determining the design value. The EPA Regional offices will work with the State to determine the validity of flagged data. Flagged data may be excluded on a case-by-case basis depending on State documentation of the circumstances justifying flags. Data flagged as affected by exceptional or natural events will generally not be used when determining the design value. However, in order for data affected by a natural event to be excluded, an adequate Natural Events Action Plan is required as described in the Natural Events policy.

Data flagged as affected by wildland and prescribed fires will be used in determining the design value. If the State is addressing wildland and prescribed fire use with the application of smoke management programs, the State may5

submit an LMP if the design value is too high only as a result of the fire-affected

data.

We are in the process of developing a policy to address agricultural burning. When it is finalized we will amend the LMP option to account for the new policy.

V. What should an LMP consist of ?

Under the LMP, we will continue to satisfy the requirements of Section 107(d)(3)(E) of the Act which provides that a nonattainment area can be redesignated to attainment only if the following criteria

are met:

1. The EPA has determined that the NAAQS for the applicable pollutant has been

attained.

2. The EPA has fully approved the applicable implementation plan under section 110(k).

3. The EPA has determined that the improvement in air quality is due to permanent

and enforceable reductions in emissions.

4. The State has met all applicable requirements for the area under section 110 and part

D.

5. The EPA has fully approved a maintenance plan, including a contingency plan, for the

area under section 175A.

However, there are some differences between what our previous guidance (the Calcagni memo) recommends that States include in a maintenance plan submission and what we are recommending under this policy for areas that qualify for the LMP. The most important difference is that under the LMP the demonstration of maintenance is presumed to be satisfied. The following is a list of core provisions which should be included in an LMP submission. Note that any final EPA determination regarding the adequacy of an LMP will be made following review of the plan submitted in light of the particular circumstances facing the area proposed for redesignation and based upon all

available information.

a. Attainment Plan

The State’s approved attainment plan should include an emissions inventory (attainment inventory) which can be used to demonstrate attainment of the NAAQS. The inventory should represent emissions during the same five-year period associated with the air quality data used to determine whether the area meets the applicability requirements of this policy (i.e., the most recent five years of air quality data). If the attainment inventory year is not one of the most recent five years, but the State can show that the attainment inventory did not change significantly during that five-year period, it may still be used to satisfy the policy. If the attainment inventory is determined to not be representative of the most recent 5 years, a new inventory must be developed. The State should6

review its inventory every three years to ensure emissions growth is incorporated in the attainment inventory if necessary.

b. Maintenance Demonstration

The maintenance demonstration requirement of the Act will be considered to be satisfied for the

moderate PM 10 nonattainment areas meeting the air quality criteria discussed above. If the tests described in Section IV are met, we will treat that as a demonstration that the area will maintain the NAAQS. Consequently, there is no need to project emissions over the maintenance period.

c. Important elements that should be contained within the redesignation request

1. Monitoring Network Verification of Continued Attainment

To verify the attainment status of the area over the maintenance period, the maintenance plan should contain a provision to assure continued operation of an appropriate, EPA-approved air quality monitoring network, in accordance with 40 CFR part 58. This is particularly important for areas using an LMP because there will be no cap on emissions.

2. Contingency Plan

Section 175A of the Act states that a maintenance plan must include contingency provisions, as necessary, to promptly correct any violation of the NAAQS which may occur after redesignation of the area to attainment. These contingency measures do not have to be fully adopted at the time of redesignation. However, the contingency plan is considered to be an enforceable part of the SIP and the State should ensure that the contingency measures are adopted as soon as possible once they are triggered by a specific event. The contingency plan should identify the measures to be adopted, and provide a schedule and procedure for adoption and implementation of the measures if they are required. Normally, the implementation of contingency measures is triggered by a violation of the NAAQS but the State may wish to establish other triggers to prevent a violation of the NAAQS, such as an exceedance of the NAAQS.7

3. Approved attainment plan and section 110 and part D CAA requirements :

In accordance with the CAA, areas seeking to be redesignated to attainment under the LMP policy must have an attainment plan that has been approved by EPA, pursuant to section 107(d)(3)(E). The plan must include all control measures that were relied on by the State to demonstrate attainment of the NAAQS. The State must also ensure that the CAA requirements for PM 10 pursuant to section 110 and part D of the Act have been satisfied. To comply with the statute, the LMP should clearly indicate that all controls that were relied on to demonstrate attainment will remain in place. If a State wishes to roll back or eliminate controls, the area can no longer qualify for the LMP and the area will become subject to full maintenance plan requirements within 18 months of the determination that the LMP is no longer in effect.

V. How is Conformity treated under the LMP option?

The transportation conformity rule (40 CFR parts 51 and 93) and the general conformity rule (58 FR 63214; November 30, 1993) apply to nonattainment areas and maintenance areas operating under maintenance plans. Under either conformity rule one means of demonstrating conformity of Federal actions is to indicate that expected emissions from planned actions are consistent with the emissions budget for the area. Emissions budgets in LMP areas may be treated as essentially not constraining for the length of the maintenance period because it is unreasonable to expect that an area satisfying the LMP criteria will experience so much growth during that period of time such that a

violation of the PM 10 NAAQS would result. While this policy does not exempt an area from the need to affirm conformity, it does allow the area to demonstrate conformity without undertaking certain requirements of these rules. For transportation conformity purposes, EPA would be concluding that emissions in these areas need not be capped for the maintenance period, and, therefore, a regional emissions analysis would not be required. Similarly, Federal actions subject to the general conformity rule could be considered to satisfy the “budget test” specified in section 93.158 (a)(5)(i)(A) of the rule, for the same reasons that the budgets are essentially considered to be unlimited.

EPA approval of an LMP will provide that if the LMP criteria are no longer satisfied and a full maintenance plan must be developed to meet CAA requirements (see Calcagni Memo referenced in footnote #2 for full maintenance plan guidance), the approval of the LMP would remain applicable for conformity purposes only until the full maintenance plan is submitted and EPA has found its motor vehicle emissions budgets adequate for conformity purposes under 40 CFR parts 51 and 93. EPA will condition its approval of all LMPs in this fashion because in the case where the LMP criteria are not met and a full maintenance plan is required EPA believes that LMPs would no longer be an appropriate mechanism for assuring maintenance of the standards.

For further information concerning the LMP option for moderate PM 10 areas please contact8

Gary Blais at (919) 541-3223, or for questions about the CDV approach contact Dr. Shao-Hang Chu at (919) 541-5382. For information concerning transportation conformity requirements, please contact Meg Patulski of the Office of Transportation and Air Quality at (734) 214-4842.9

OAQPS/AQSSD/IPSG:GBlais:NPerry,x5628 G:\user\share\nrpfiles\wpfiles\beal\LMP.wpd

### ATTACHMENT B:

MOTOR VEHICLE REGIONAL ANALYSIS METHODOLOGY

The following methodology is used to determine whether increased emissions from on-road mobile sources could, in the next 10 years, increase concentrations in the area and threaten the assumption of maintenance that underlies the LMP policy. This analysis must be submitted and approved in order to be eligible for the LMP option.

The following equation should be used:

DV + (VMT

pi x DV

mv ) # MOS

Where:

DV = the area’s design value based on the most recent 5 years of quality

assured data in μg/m 3

VMT pi = the projected % increase in vehicle miles traveled (VMT) over the next 10 years

DV

mv = motor vehicle design value based on on-road mobile portion of the

attainment year inventory in μg/m 3

MOS = margin of safety for the relevant PM-10 standard for a given area: 40

μg/m 3 for the annual standard or 98 μg/m 3 for the 24-hour standard

Please note that DV

mv is derived by multiplying DV by the percentage of the attainment year inventory represented by on-road mobile sources. This variable should be based on both primary and secondary

PM 10 emissions of the on-road mobile portion of the attainment year inventory, including re-entrained

road dust.

States should consult with EPA regarding the three inputs used in the above calculation, and all EPA comments and concerns regarding inputs and results should be addressed prior to submitting a limited maintenance plan and redesignation request.

The VMT growth rate (VMT pi ) should be calculated through the following methods:

1) an extrapolation of the most recent 10 years of Highway Performance Monitoring System (HPMS) data over the 10-year period to be addressed by the limited maintenance plan; and

2) a projection of VMT over the 10-year period that would be covered by the limited maintenance plan, using whatever method is in practice in the area (if different than #1).

Areas where method #1 is the current practice for calculating VMT do not also have to do calculation #2, although this is encouraged. All other areas should use methods #1 and #2, and VMT pi is2

whichever growth rate produced by methods #1 and #2 is highest. Areas will be expected to use transportation models for method #2, if transportation models are available. Areas without transportation models should use reasonable professional practice.

Examples

1. DV = 80 μg/m 3

VMT pi = 36%

DV

mv = 30 μg/m 3

MOS = 98 μg/m 3 for 24-hour PM-10 standard

80 + (.36 * 30) = 91

Less than 98 – Area passes regional analysis criterion.

2. DV = 35 μg/m 3

VMT pi = 25%

DV

mv = 6 μg/m 3

MOS = 40 μg/m 3 for annual PM-10 standard

35 + (.25 * 6) = 37

Less than 40 – Area passes regional analysis criterion.

3. DV = 115 μg/m 3

VMT pi = 25%

DV

mv = 60 μg/m 3

MOS = 98 μg/m 3 for 24-hour PM-10 standard

115 + (.25 * 60) = 130

More than 98 – Area does not pass criterion. Full section 175A maintenance plan required.

## ATTACHMENT 4STATE OF NEW HAMPSHIRE
DEPARTMENT OF ENVIRONMENTAL SERVICES

AIR RESOURCES DIVISION CONCORD, NH

NOTICE OF PROPOSED REVISIONS TO THE STATE IMPLEMENT ATION PLAN

In accordance with N.H. Administrative Rule Env-A 2 04.01 and 40 CFR § 51.102, notice is hereby given that the New Hampshi re Department of Environmental Services, Air Resources Division (DES), intends to submit for the approval of the U.S. Environmental Protection Agency (EPA) the following proposed revisions to the New Hampshire State Implementation Plan (SIP) required by the federal Clean Air Act:

• Replace New Hampshire’s existing Carbon Monoxide Ma intenance Plan with the proposed Carbon Monoxide Limited Maintenance Plan for the Ci ty of Manchester and the City of Nashua Carbon Monoxide Maintenance Areas.

• Discontinue monitoring Carbon Monoxide (CO) at the Manchester site and rely instead on data from the Londonderry Moose Hill mon itoring station and NH emissions inventory.

When an area (in this case Manchester and Nashua) t hat was previously designated as nonattainment for any of the pollutants for which E PA has established National Ambient Air Quality Standards (NAAQS) applies for redesigna tion to attainment status, the federal Clean Air Act requires DES to submit a main tenance plan as part of the redesignation request. This plan shows how the are a will stay in attainment for the subsequent 10 years, and what steps DES will take i f it does not. DES filed a maintenance plan for CO with EPA on December 3, 199 8, and revised it in 2007.

Over time, the CO levels in downtown Manchester and Nashua have decreased to the point that a future exceedance of the federal stand ards for CO is highly unlikely. In addition to the downward CO trend shown by monitori ng data, the state has performed mobile source modeling and conformity analyses indi cating low CO levels in Manchester and Nashua as far into the future as 2035, beyond t he end of the maintenance plan. Therefore, DES is submitting a CO Limited Maintenan ce Plan that will discontinue CO monitoring in Manchester, instead relying on a CO m onitoring station in Londonderry, mid-way between Manchester and Nashua, with conting ency plans to reinstate monitoring in Manchester if CO concentrations rise to 50 percent of the NAAQS.

Copies of all documentation pertaining to the propo sed SIP revision are available for inspection online at: http://des.nh.gov/ under “Hot Topics”. The documents are also
available for review at the DES offices at 29 Hazen Drive, Concord, N.H. Questions regarding the proposed SIP Revision or requests to view the documents should be directed to Paul Lockwood at (603) 271-5552 or paul.lockwood@des.nh.gov

.

The public is invited to submit written comments on the proposal, and DES will hold a public hearing if one is requested by July 23, 2012 . Written comments and/or anyrequests for a public hearing filed and received no later than 4 p.m. on July 23, 2012,

shall be considered by DES in making a final decisi on. Please submit comments or a request for hearing to Paul Lockwood, Transportatio n Analyst, PO Box 95, Concord, NH 03302-0095, Fax (603) 271-7053, or to paul.lockwood@des.nh.gov

.

Thomas S. Burack
Commissioner NH Department of Environmental Services

Dated: June 23, 2012

## ATTACHMENT 5