# Northern Ada County Air Quality Maintenance Area

Second 10-Year Carbon Monoxide Limited

Maintenance Plan

February 2011

Prepared by:

Idaho Department of Environmental Quality 1445 North Orchard, Boise, Idaho 83706-1255

### Table of Contents

1. Introduction .............................................................................................................................. 2 2. Background - Nonattainment Designat ion and Redesignation to Attainment .................. 2 3. Maintenance Area Description ............................................................................................... 2 4. Requirement for Second Maintenance Plan .......................................................................... 3 5. Limited Maintenance Plan Option ......................................................................................... 3 5.1 Attainment Year Emissions Inventory ............................................................................. 3

A. Point Sources ..................................................................................................................... 4

B. Area Sources ...................................................................................................................... 4
C. On Road Mobile Sources .................................................................................................. 4
D. Non-Road Mobile Sources ................................................................................................ 5

5.2 Maintenance Demonstration .............................................................................................. 5 A. Air Quality Criteria .......................................................................................................... 5
B. Maintenance Plan Control Measures .............................................................................. 6 5.3 Monitoring Network /Verific ation of Continued Attainment ........................................ 8 5.4 Contingency Plan ............................................................................................................... 8 A. Contingency Measure Triggering Protocol ...................................................................... 8 B. Contingency Measures ...................................................................................................... 8 5.5 Conformity .......................................................................................................................... 8 A. Transportation Conformity ............................................................................................... 9 B. General Conformity ......................................................................................................... 10

6. Conclusion .............................................................................................................................. 10

Appendix A. Legal Description for Ada County CO Maintenance Area Appendix B. References Appendix C. Emissions Inventory Appendix D. U.S. EPA Air Quality System Quick Look Report Appendix E. Ada County Vehicle Inspecti on and Maintenance Program Appendix F. Rules Establishing State Authority Appendix G. Public Comment, Public Hearing and Response

Tables Table 1 – 2008 Ada County Carbon Monoxide Emissions...........................................4

Table 2 – 2 nd Max 8-Hour Monitored CO Values......................................................6

Figures Figure 1 – Map of Northern Ada County CO Maintenance Area...................................2 Figure 2 – Northern Ada County Carbon Monoxide Trend..........................................5

1

### Northern Ada County Second 10-Year Limited Maintenance Plan

1. Introduction The Clean Air Act requires that an area redesigna ted from nonattainment to maintenance submit to the Environmental Protection Agency (EPA) a plan for maintaining the National Ambient Air Quality Standards (NAAQS) for a second 10-year period. This Northern Ada County limited maintenance plan was prepared by the Idaho De partment of Environmental Quality (DEQ) for inclusion into the Idaho State Implementation Pl an (SIP) and will serve as the second 10-year maintenance plan for the Northern Ada Count y carbon monoxide (CO) maintenance area. The plan demonstrates that Northern Ada County will maintain the CO standard for a second 10-year period following the expiration of the first plan.

2. Background - Nonattainment Designat ion and Redesignation to Attainment Northern Ada County (Boise), Idaho, was desi gnated nonattainment for CO and classified as “not classified” upon enactment of the Clean Air Act (CAA) Amendments in 1990 based on violations of the 8-hour CO NAAQ S. In January 2002, DEQ submitted a Limited Maintenance Plan and Request for Redesignation to Attain ment for the Northern Ada County Carbon Monoxide Not-Classified Nonattainment Area to the EPA to support rede signation of the area to attainment status. The plan was approved in December 2002 and the area reclassified to

attainment for CO 1

.

CO levels in Ada County have dropped since the 1970s due initially to th e Vehicle Inspection and Maintenance (I/M) program and subsequently to federal vehicle emissions standards. In addition, efforts to increase the use of altern ative transportation, as well as improvements in traffic flow in downtown Boise, have reduced congestion and minimized opportunities for CO pollution to build up in hotspot areas. The last exceedance of the NAAQS for CO in Northern Ada County was in January 1991. No violations (m ore than one exceedance of the standard in a single year) have been recorded since 1986.

3. Maintenance Area Description The Northern Ada County Maintenance Area consis ts of only the portion of Ada County that is north of the Boise baseline (43 degree s north latitude) as shown in Figure 1.

Figure 1 – Map of Northern Ada County CO Maintenance Area (Shaded Area).

1 Approval and Promulgation of Air Quality Implementation Plans; State of Idaho; Northern Ada County Carbon Monoxide Redesignation to Attainment. 67 Fed Reg. 65713-65718, October 28, 2002. Available at: http://yosemite.epa.gov/r10/airpage.nsf/283d45bd5bb068e68825650f0064cdc2/e2ab2cc6df433b8688256b2f00800ff 8/$FILE/67%20FR%2065713.pdf

2South of the baseline the land is largely unpopulated and is primarily managed by federal agencies such as the Bureau of Land Ma nagement and the Idaho National Guard.

To the east and north, the Boise front blocks m ovement of air and pollution between Ada County and neighboring Boise, Elmore, and Gem Counties.

Canyon County is located on the western edge of the maintenance area is populated and has

sources of carbon monoxide.

The legal description for the mainte nance area can be found in Appendix A.

4. Requirement for Second Maintenance Plan Section 175A of the CAA Amendments requires redesignated areas to submit a second maintenance plan to EPA eight years after the first plan has been approved. The second plan must demonstrate continued compliance with the NAAQS during the 10- year period following expiration of the first plan. As with the first Northern Ada County CO 10 -Year Limited Maintenance Plan, this second plan qualifies for the limited maintenance plan option in accordance with the October 6, 1995, EPA memorandum, “Limited Maintenance Plan Option for Nonclassifiable CO Nonattainment Areas,” from Joseph W. Paisie, Group Leader, Integrated Policy and Strategies Group (hereafter “the Paisie Memo”; see Appendix B – References Cited). Specific criteria and compliance methods are discussed in the following section.

5. Limited Maintenance Plan Option As required by the limited maintenance plan opti on, the core provisions to be included in a limited maintenance plan for CO nonclassifiab le areas are an attainment inventory, a maintenance demonstration, continued operation of a monitoring network, a contingency plan, and conformity determinations.

5.1 Attainment Year Emissions Inventory In accordance with the Paisie Memo, Idaho is a dvised to provide an emissions inventory that “should represent emissions during the time period associated with the monitoring data showing attainment. The inventory should be based on ac tual “typical winter day” emissions of CO.”

A comprehensive emissions inventory has been completed for carbon monoxide for 2008. The emissions inventory includes Ad a County in its entirety, as oppos ed to just the Northern Ada County Maintenance Area. This is a more cons ervative approach that meets the maintenance plan requirements, while supporting the “airshe d management” approach used by DEQ. The emissions inventory is attached as Appendix C. Table 1 shows the 2008 annual as well as average winter day carbon monoxi de emissions for the maintenance area. The average winter day season used was calculated from November 1 through February 29, 2008 (2008 was a leap year).

3Table 1. 2008 Ada County Carbon Monoxide Emissions – Annual and Average Winter Day Emissions ( 2008, 2015, and 2023 Emissions Inventories fo r the Treasure Valley Airshed )

Source 2008 Annual Emissions 2008 Average Winter Day

Emissions

Tons Per Year Percent of Total Tons Per Day Percent of Total

Point Sources 198.5 .2 0.5 .2 Major Point Sources

w/in 25 miles 862.4 1.1 4.2 1.6

Area Sources 7,715.1 9.5 49.7 18.8

On-Road Mobile 45,574.2 55.9 146.1 55.2

Non-Road Mobile 24,870.5 30.5 62.5 23.6 Total Anthropogenic 79,220.7 263.0 Biogenic 2,246.5 2.8 1.5 .6

Total 81,467.2 264.5

A. Point Sources The emissions inventory developed for Ada County is a multi-pollutant inventory. To capture all pollutants and all facilities, facil ities were divided into point or area sources based on emissions of all pollutants. If a facility exceeds a defined point for any pollu tant, it is included as a point source for all pollutants. The Tr easure Valley Emissions Inventory defines point sources as any facility emitting greater than any of the following thresholds: 5 tons per year of PM 10 , PM 2.5 , SO

x , or NH 3 ; 10 tons per year of volatile organi c compounds; or 25 tons per year of NO

x or CO. Therefore, facilities were included in the point source category for CO if they exceeded the limit for any pollutant.

To be consistent with the approved Decembe r 2002 maintenance plan and included emissions inventory, facilities that emit in excess of 100 tons per year of CO and are within a 25-mile radius of the maintenance area, but are not wi thin the maintenance ar ea boundaries, are included in the CO inventory for Northern Ada County. These facilities ar e included in a separate line

item in Table 1. This adds an additional 862.4 tons per year or 1.1% of the total to the CO emissions for the maintenance area. In total, point sources accounted for 1,060.9 tons per year or

1.3% of the CO emissions.

B. Area Sources

In the Handbook for Criteria Pollutant Inventory Development: A Beginner’s Guide for Point

and Area Sources , the EPA describes area sources as “faci lities or activities whose individual emissions do not qualify them as point sources. Area sources represent numerous facilities or activities that individually release small amounts of a given pollutant, but collectively they can release significant amounts of a pollutant.” Fo r the purposes of this emission inventory, area sources are defined as those sources emitting an nual emissions less than the point source thresholds. Area sources accounted for 7,715.1 tons per year or 9.5% of the annual total.

C. On Road Mobile Sources Motor vehicles remain the largest carbon monoxid e source in the maintenance area, accounting

for 55.9% of the annual total and 55.2% of the av erage winter day emissions. On-road mobile source emissions were estimated using vehicle m iles traveled (VMT) data and emissions factors from EPA’s MOBILE6 vehicle model using outp uts from the Community Planning Association

4(COMPASS) transportation demand model (TDM ). COMPASS is the metropolitan planning organization (MPO) for Northern Ad a County and the Treasure Valley.

D. Non-Road Mobile Sources Non-road mobile sources encompass a wide variet y of equipment that either move under their own power or are capable of bei ng moved from site to site. N on-road mobile equipment sources not licensed or certified as highway vehicles are defined as those that move or are moved within a 12-month period and are covered under EPA's emissions regulations as non-road mobile sources. The three types of non-road mobile s ources are non-road equipment, locomotives, and

aircraft. Non-road mobile sources accounted for 30.5% of the annual and 23.6% of the average winter day carbon m onoxide emissions.

5.2 Maintenance Demonstration

In accordance with the Paisie Memo “The maintenance demonstration requirement is considered to be satisfied for nonclassifiable areas if the mon itoring data show that th e area is meeting the air quality criteria for limited maintenance ar eas (7.65 ppm or 85% of the CO NAAQS......The EPA believes if the area begins the maintenance period at or below 85 percent of exceedances levels, the air quality along with the continued applicability of PSD requirements, any control measures already in the SIP, and Federal me asures, should provide adequate assurance of maintenance over the initial 10-year maintenance period.” All of these criteria have been met in the Northern Ada County carbon monoxide maintenance area.

A. Air Quality Criteria The last exceedance of the NAAQS for CO was in January 1991; however, no violation of the NAAQS occurred at that time. No violations (m ore than one exceedance of the standard in a single year) have been recorded since 1986. Curre nt CO levels are well below the 8-Hour NAAQS of 9 ppm, with a 2008 design value of 2.9, or 32.2% of the NAAQS. Additionally, as illustrated in Figure 2, the maintenance area has s hown a generally declining trend in the ambient eight-hour concentrations ove r the past several years.

Northern Ada County Highest and Second Highest EightHour Average Carbon Monoxide Concentration

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0

19

9 5 1996 19 97 19 9 8 19 9 9 2000 20 01 20 02 2003 2 0 04 20 05 20 06 2007 2 0 08 CO - Highest

Co 2nd Highest

Figure 2 – Northern Ada County Carbon Monoxide Trend

5Design value is based on the second highest non-overlapping running eight-hour ambient carbon monoxide concentrations measured in eight cons ecutive quarters (two year s of data). The method for calculating design values is presented in the June 18, 1990, EPA memorandum “Ozone and Carbon Monoxide Design Value Calculations,” fr om William G. Laxton, former director of the OAQPS Technical Support Division to Regional Air Directors (see Appendix B – References Cited) . 2007 and 2008 data are used for this maintena nce plan. These years are representative of current emissions levels. Design values for the last five years are presented in Table 2.

Table 2. 2 nd Max, 8-Hour Monitored CO Values

Year 2 nd Max Value

2004 2.4 ppm
2005 2.2 ppm
2006 2.1 ppm
2007 1.6 ppm
2008 2.9 ppm Source: U.S. EPA Air Quality System Quick Look Report – see Appendix D.

As shown in Table 2, the highest 2 nd Max value of 2.9 ppm is well below the 7.65 ppm threshold established for the limited maintenance plan option and significantly below the eight-hour NAAQS of 9 ppm.

B. Maintenance Plan Control Measures

The control measures included in the initial Northern Ada County maintenance plan will be continued in the second 10-year maintenance plan.

1. Federal Motor Vehicle Emissions Control Program A significant reduction in carbon monoxide emissions can be attributed to the federal motor vehicle emissions control program. Emissions sta ndards for motor vehicles are established under

Title II of the Clean Air Act. As newer vehicl es replace older, more polluting vehicles, these

standards will continue to have an increasing role in reduci ng carbon monoxide emissions. This program is federally enforced.

2. Controls on Stationary Sources Idaho has a federally approved New Source Re view Program, including a Prevention of Significant Deterioration progr am. Major sources that are new or are undergoing major modifications will continue to be required to undergo Prevention of Significant Deterioration review, which includes requirements for Best Available Control Technology. New minor sources or sources undergoing minor modifications must obtain a Permit to Construct, which includes provisions to ensu re protection of the NAAQS.

3. Ada County Vehicle Inspection and Maintenance (I/M) Program Vehicles registered in Ada County are required to pass an emissions test or face revocation of registration.

Under local ordinances emissions testing is mandatory in Ada County, the cities of Boise, Meridian, Garden City, and Ea gle. Modifications enacted be tween July 2000 and January 2001 have made the I/M Program even more effective. Changes include:

• Lowering the carbon monoxide cut-poin t, or allowable percentage

6• Adding a standard for hydrocarbon emissions

• Modifying the waiver policy so initial waiver s can be issued only after at least $300 in repair work has been done on the vehicle

• Adding diesel vehicles to the list of vehicles required to pass an emissions test

• Expanding the test from idle only to a two- speed test conducted at both idle and at 2,500 revolutions per minute

• Eliminating the test and repair option for test st ations and their owners.

• Stations are no longer permitted to offer re pair services to correct emissions. These improvements were not required by the Air Quality Improvement Plan.

Although the I/M Program is currently operate d under local ordinan ces, the Idaho State Constitution authorizes the legislature to impose rules relating to motor vehicles.

State legislation passed by the 2008 legislature will impact implementation of I/M programs in Idaho in the future. Idaho Code § 39-116B ma ndates a vehicle emission testing program, or a program that results in equivalent motor vehicle emission reductions if the following triggers are met: the design value of any criteria pollutant exceeds 85% of a NAAQS and motor vehicles constitute one of the top two sources of th at pollutant. Based on the ozone design value exceeding 85% of the NAAQS, and motor vehicles being one of the top two sources of ozone precursors, these triggers have been met in th e Treasure Valley and as a result, an emission testing or equivalent program is now mandated in Ada County by state law, in addition to the local ordinances previously relied upon to mandate the program. Also as a result of the 2008 state law, an I/M program requiring biennial testing was implemented in adjacent Canyon County in June 2010. While not federally mandated or included as a control measure in the State Implementation Plan (SIP), this program is expect ed to provide additional air quality benefits for the Northern Ada County Maintenance Area.

The current I/M testing in Ada County will continue , but to ensure consistency with existing or future potential I/M programs administered under state law and rules, frequency of testing will be adjusted to biennial. The move to biennial testing was a ddressed in Appendix B1 of the 2002 approved CO Maintenance Plan for Northern Ada County which stated, “Moving from annual to biennial (every other year) testing was planne d to begin in July of 2000. The Emissions Inventory for the Northern Ada County Carbon M onoxide Limited Maintenan ce Plan reflects this change. The Mobile 5b model used to estimate em issions interprets this change to result in slightly increased carbon monoxide emissions , as vehicles with excessive emissions would potentially not be repaired as often.” The switch to biennial testi ng is also supported by the CO Emissions Inventory for the Trea sure Valley (see Appendix C).

The new testing protocol in eff ect in Ada County is as follows:

• Testing is required biennially

• Vehicles from model year 1981 to 1995 are tested using the tailpipe/exhaust (TSI)

method

• Vehicles from model year 1996 and newe r are tested usi ng the OBD II method

• First five model years are exempt from testing

• All cut-points will remain unchanged

7See appendix E - Description of Ada County Vehicl e Inspection and Maintenance Program for

links to rules and ordinances relate d to and requiring emissions testing.

5.3 Monitoring Network /Verific ation of Continued Attainment

In accordance with the Paisie Memo “...the maintenance plan should contain provisions for continued operation of an appropriate, EPA-appr oved air quality monitoring network, in

accordance with 40 CFR Part 58.”

Ambient CO concentrations con tinue to be low, with a current design value of 32% of the NAAQS. With monitoring data used as the trigge ring mechanism, DEQ will continue to closely track CO concentrations and to verify continue d attainment via the approved monitoring network operated in accordance with 40 CFR Part 58.

5.4 Contingency Plan

In accordance with the Paisie Memo “Section 175A of the Clean Air Act requires that a maintenance plan include contingency provisions as necessary, to promptly correct any violation of the NAAQS that occurs after redesignation of the area. These contingency measures do not have to be fully adopted at the tim e of redesignation. ... The State s hould also identify specific indicators, or triggers, which will be used to determine when the contingency measures need to be implemented.”

A. Contingency Measure Triggering Protocol Implementation of carbon monoxide contingency measures will be triggered under the following two circumstances: (1) immediately upon any exceedance of the Carbon Monoxide NAAQS, based on quality assured data, recorded at any site within the maintenance area or (2) if quality assured monitoring data show non-overlap ping eight-hour average carbon monoxide concentrations of 8.0 ppm on four or more days within a si ngle winter season (November through March) within the maintenance area.

B. Contingency Measures If either of these two triggers is activated, DEQ will initiate one of the following contingency

measures: (1) Oxygenated Fuels Program DEQ will promulgate a rule through the Boar d of Environmental Quality requiring all gasoline fuels dispensed in the maintenance ar ea to contain ethanol at a minimum of ten percent (10%) by volume. (2) Alternative EPA-Approved Contingency Measure DEQ understands EPA is reviewing the eff ectiveness of oxygenated fuels as a carbon monoxide reduction measure and may provide guidance on more effective alternative contingency measures for carbon monoxide reduction. Should a more effective EPAapproved contingency measure become available DEQ will negotiate and implement the

alternative.

5.5 Conformity

In accordance with the Paisie Memo “...In areas with approved limited maintenance plans, Federal actions requiring conformity determinations under the transportation conformity rule could be considered to satisfy the “bu dget test” required in sections; 93.118, 93.119 and 93.120 of the rule. Similarly, in thes e areas, Federal actions subject to the general conformity rule

8could be considered to satisfy the “budget te st” specified in secti on 93.158(a)(5)(i)(A ) of the

rule.”

A. Transportation Conformity Although a budget test is not requir ed, EPA has not precluded stat es and local agencies from satisfying other requirements of the conform ity process. For transportation conformity, components of the conformity process include analysis of hotspots, c onsultation on applicable actions, and implementation of any Transportati on Control Measures specified in state and federal transportation conformity rules.

As identified in 40 CFR 93.105, the lead transpor tation planning agency is responsible for demonstrating compliance with tr ansportation conformity requirem ents. The lead transportation agency in Ada County is COMPASS, the me tropolitan planning organization. COMPASS will oversee transportation conformity determinations of the Interagency Consultation Committee (ICC), a group of representatives of state and lo cal transportation agencies, the state air quality agency, Department of Transportation (DOT) and EPA, as specified in 40 CFR 93.105 (51.402) and the Idaho Transportation Conformity Rule located in the Rules for the Control of Air Pollution in Idaho, IDAPA 58.01.01.563 through 574. Th e ICC is responsible for overseeing development of conformity analyses. The Ida ho Transportation Conformity Rule was finalized on April 12, 2001. This rule adopts by reference por tions of 40 CFR Part 93, Subpart A, Section 100-129 (see Appendix F - Rules Estab lishing State Authority ).

DEQ will continue use of the build/no-build an alysis conducted by COMPASS. This analysis will be used for planning purposes, future emission analyses, and as assurance that transportation

activities will not lead to carbon monoxide emissi ons that could contribute to exceedances of the NAAQS. If the build scenario is larger than no-build, the next test step for determining conformity will be to compare the build sc enario to 1990 emissions, as allowed by the conformity rule under 40 CFR Part 93.119(c)(ii). If the build scenario is below 1990 emissions, conformity is demonstrated.

Regionally significant projects are also subject to conformity analysis. The ICC has developed the following definiti on of a “Regionally Significant” project:

A transportation project in Ada County, Idaho is designated “Regiona lly Significant” if:

(a) the project is fo r the improvement of either: (i) a principal arterial or higher functional classification; or (ii) a minor arterial which will have a twenty (20) year projected traffic volume of at least 45,000 vehicles a day after completion of the project;

and (b) the project will add at least one new continuous vehicular lane which

either: (i) extends from one intersecti ng principal or minor arterial to another intersecting principal or minor arterial; or (ii) in the case of an interst ate, extends from the on ramp of one interstate interchange to a point beyond the off ramp of the next adjacent interstate interchange.

910 This definition is based on the federal definition of regional significance, as specified in 40 CFR 93, and takes into account local f eatures. This definition is a dynamic process that may change as conditions change. COMPASS is the designate d contact for the most current definition.

For any transportation plans, programs, or project s that meet these criteria, the ICC will conduct an analysis to determine if the action could cau se or contribute to an exceedance of the carbon monoxide NAAQS. The analysis will be conducted according to procedures specified in 40 CFR 93.100-182. For any regionally significant plans, pr ograms, or projects that show potential

carbon monoxide concentrations exceeding the standards, mitiga tion measures will be required.

B. General Conformity Although a budget test is not requir ed, EPA has not precluded stat es and local agencies from satisfying other requirements of the general confor mity process. For any ne w projects or actions identified in 40 CFR 93.150, the federal agency overseeing the project is responsible for conducting a conformity analysis. DEQ will provide guidance to the federal agency to ensure compliance is achieved. IDAPA 58.01.01.123 authorize DEQ to require respons ible agencies to provide certified information about the project. Ag encies are advised to be gin to work with DEQ during early stages of planni ng to determine the expected quantity of carbon monoxide emissions. If expected carbon monoxide emissions ar e greater than or equal to 100 tons per year, the deminimus threshold analysis specified in 40 CFR 51.853 must be conducted to determine the magnitude of emissions and impact on carbon monoxide concentrations. This analysis must be conducted according to procedures specifi ed in 40 CFR 93.158. If necessary, mitigation measures must be applied as specified in 40 CFR 93.160. DEQ will review and comment on conformity determinations.

6. Conclusion DEQ has shown that the Northern Ada County CO Maintenance Area has stayed well below the NAAQS for CO, and that there is little risk of future NAAQS violations. Having met all criteria for the Second 10-year maintenance plan, DEQ as ks EPA to approve this Second 10-year CO Limited Maintenance Plan for the Northern Ada County CO Maintenance Area.