# Enclosure V

ARB Staff Report

# State of California

California Environmental Protection Agency



# AIR RESOURCES BOARD

Staff Report



# Analysis of the Sacramento Metropolitan Air Quality Management District PM10 Implementation/Maintenance Plan and Redesignation Request for Sacramento County

Release Date: October 29, 2010 Scheduled for Consideration: November 18-19, 2010This document has been reviewed by the staf f of the California Air Resources Board and approved for publication. Approval does not signify that the contents necessarily reflect the views and policies of the Air Res ources Board, nor does the mention of trade names or commercial products constitute endorsement or recommendation for use.TABLE OF CONTENTS

EXECUTIVE SUMMARY 1

I. BACKGROUND 2

II. REDESIGNATION REQUIREMENTS 3

III. EVALUATION OF THE SACRAMENTO PM10 PLAN 4

A. Sacramento County Attains the 24-Hour PM10 Standard 4

B. The State Has Met Applicable Act Requirements 6

C. Improvement in Sacramento PM10 Air Quality is Due to
Permanent and Enforceable Reductions in Emissions 6

D. Maintenance Plan 7

1. Attainment Emission Inventory 7
2. Maintenance Demonstration 8
3. PM10 Monitoring Network 9
4. Verification of Continued Attainment 10
5. Contingency Provisions 10
6. Transportation Conformity Budgets 10

IV. STAFF RECOMMENDATION 12EXECUTIVE SUMMARY

The Sacramento Metropolitan Air Quality Ma nagement District (District) shares the same jurisdictional boundary as Sacr amento County (Count y) and has prepared
documentation to demonstrate that the Count y now meets the remaining federal health standard for particulate matter of 10 microns in diameter or smaller (PM10) and should be redesignated to attainment. On July 1, 1987, the United St ates Environmental Protection Agency (U.S. EPA) adopted the PM 10 national ambient air quality standard (NAAQS or standard) consisting of an annual average standard of 50 μ g/m 3 , and a
24-hour standard of 150 μ g/m 3 . Subsequently, on December 18, 2006, U.S. EPA
revoked the national annua l average PM10 standard.

In 1994, U.S. EPA designated the County a moderate nonattainment area, with an attainment deadline of December 31, 2000. Effective March 18, 2002, U.S. EPA officially determined that m onitors in the County measur ed air quality attaining the 24-hour PM10 standard by the moderate area deadline. The District must provide documentation specified in t he federal Clean Air Act (the Act) demonstrating the
24-hour PM10 standard can be maintained in order to request that U.S. EPA redesignate the County to attainment.

The District prepared the PM10 Implementat ion/Maintenance Plan and Redesignation Request for Sacramento County (Sacramento PM10 Plan or Plan) as required. The Plan affirms the County has attained t he standard and demonstrates that existing federal, State, and local control measures will maintain the 24-hour PM10 standard in the District. On October 28, 2010, the District Board adopted the Plan at a public hearing.

The Plan contains all elements needed for redesignation to attainment:

 Demonstration that PM10 attainment concentrations measured between 2007
and 2009 will be maintained for ten years after redesignation;

 Commitment that the monitoring network will be maintained to track attainment for at least ten years after redesignation;

 Contingency provisions for correcting any future violations of the PM10 NAAQS;

 Emission inventories for PM 10 and nitrogen oxides (NOx);

 Transportation conformity budgets which sets limits for mobile source emissions of PM10 and NOx through 2022.

In addition, eight years after the U.S. EPA redesignates the area as attainment, the
District will submit a revised ma intenance plan providing for continued attainment for an additional ten years.

ARB staff concurs with the District’s Sacramento PM10 Plan and recommends the Board approve the Plan, as a revision to the California State Implementation Plan (SIP),
for submittal to U.S. EPA.

October 29, 2010 Page 1I. BACKGROUND

Sacramento County, as shown in Figure 1, wa s initially designated as a moderate PM10
nonattainm ent area in 1994 with an attainment date of December 31. 2000. The County is approximately 994 square miles in size. The population of about 1,443,000 residents has grown rapidly, increasing almost 40 percent in the past twenty years. The urbanized areas are surrounded by agricultural croplands and ranchlands. Four major interstate highways cross the county and the ma jor economic activities are related to government services, retail trade, agriculture, construction materials, and other industrial uses. Despite the changes in land use over time, there have been no
violations of the 24-hour aver age PM10 NAAQS since the mid-1990s.

Figure 1 Location of Sacramento County

October 29, 2010 Page 2On March 18, 2002, U.S. EPA determined t hat Sacramento County had attained the PM10 standard by the 2000 deadline. Base d on this clean data finding, certain
nonattainm ent area requirements do not apply, including those for reasonable further progress, an attainment demonstration, reasonably available control measures, and contingency measures, because these provision’ s sole purpose is to achieve attainment
of the standard. On Oct ober 28, 2010, the District adopt ed the Sacramento County PM10 Plan. The Plan officially requests that this area be redesignated to attainment for
the PM10 standard and charts the course for continued maintenance of the standard. The State mobile source control strategy and local District rules have resulted in Sacramento County attaining the 24-hour PM10 standard based on both past and
current data.

II. REDESIGNATION REQUIREMENTS

The Act sets the general framework for redesignation requests. In 1992, U.S. EPA provided guidance for processing redesignation requests 1 . ARB staff reviewed the
Sacramento PM10 Plan within th e context of the Act and t he U.S. EPA guidance, which identify the following requirem ents an area must meet for formal redesignation to
attainment:

A. The PM10 standard has been attained;
B. The District has an approved State Impl ementation Plan (SIP) and the State has met all applicable Act requirements fo r PM10 in the nonattainment area;
C. The improvement in PM10 air qualit y is due to permanent and enforceable emission reductions; and
D. U.S. EPA has approved a Maintenance Plan which includes these elements:
1. Attainment emission inventory;
2. Demonstration that PM10 attainment concentrations at federal reference monitoring stations will be maintained for ten years after redesignation;
3. Commitment to ongoing monitoring network operation;
4. Continued verifica tion of attainment;
5. Contingency plan to promptly correct any violation of the PM10 NAAQS that occurs after the area has been redesignated to attainment; and
6. Transportation conformity budgets for t he ten years following the anticipated year of U.S. EPA approval of the submittal.

1 A principal source of EPA guidance with respect to redesignations to atta inment can be found in a
Memorandum from U.S. EPA Office of Air Quality Planning and Standards entitled “Procedures for Processing Requests to Redesi gnate Areas to Attainment,” John Calcagni, Director, Air Quality Management Division, U.S. EPA, Research Tri angle Park, North Caroli na September 4, 1992.

October 29, 2010 Page 3III. EVALUATION OF THE SACRAMENTO PM10 PLAN

Based on review of the Sacramento PM10 Pl an and the District’s supporting technical analysis, ARB staff concur that the Plan me ets the Act’s requirem ents. The following
sections indicate how the Plan meets t he redesignation and maintenance plan requirements.

A. Sacramento County Attains the 24-Hour PM10 Standard

Currently, PM10 concentrations are measured at six monitoring sites using federal reference method monitors (F RMs). These filter-based, high-volume, size-selective inlet samplers collect PM10 samples on an hourly basis, for a 24-hour period, every six days. Figure 2 shows the location of all the ambient air monitors in Sacramento County with the FRMs for PM10 outlined in the key.

Table 1 lists the highest 24-hour average PM 10 concentration during each year for the three-year period of 2007-2009. The 24-hour PM10 standard is met when the
estimated number of exceedances measured over a three-year period averages one or less per year. The FRMs’ data demonstrate that the County atta ins the 24-hour PM10
standard.

October 29, 2010 Page 4Figure 2 PM10 Monitoring Sta tions in Sacramento County

October 29, 2010 Page 5Table 1
FRM PM10 Data from 2007 to 2009

Maximum 24-hour Average
Concentration ( μ g/m 3 ) Monitoring Station Name 2007 2008 2009 Three-year
Total Number of Days Exceeding
the Standard

Branch Center Road 56 89 76 0
Del Paso Manor 70 71 45 0
Goldenland Court* -- 56 48 0 North Highlands 56 97 33 0
Stockton Blvd 56 88 45 0
T Street 53 73 47 0 * The Goldenland Court monitor replaced the Ai rport Road monitor starting in October 2008.

B. The State Has Met Applicable Act Requirements

The Sacramento PM10 Plan serves both t he implementation and maintenance plan functions prescribed by the Act, since U.S. EPA determined that the PM10 standard was met by the 2000 deadline. ARB and the District have also met all of the Act requirements applicable for a moderate PM10 nonatta inment area to be considered for redesignation to attainment.

C. Improvement in Sacramento PM10 Air Quality is Due to Permanent and
Enforceable Reductions in Emissions

Current District rules controlling emissions of particulate matter and precursor gases (NOx, sulfur oxides (SOx), and reactive organic gases (R OG)) from stationary sources, and ARB-adopted measures governing mobile sources, have all resulted in emission reductions. In addition, the District adopted a residential wood-burning measure that curtails wood smoke during wint er months, when residential wood smoke contributes to PM10 levels. The adopted measures are fully enforceable and are explained in detail in
the Plan.

The benefit of these emissions reductions ar e indicated by the downward trend of the highest average 24-hour concentration each year at the peak Sacramento monitoring site as shown in Figure 3. These measures have provided for continuous attainment of
the 24-hour PM10 standard in t he region since the early 1990s. Based on analyses of long-term meteorological variab les, including precipitatio n, wind speed and direction, temperature, and stagnation, t he District found that meteorol ogical conditions during the 2007-2009 period were not unusually favorable to lower PM10 levels. Therefore, air quality improvements leading to PM10 attainm ent in the District are due to emission reductions from adopted, fully enforceable control measures.

October 29, 2010 Page 6Figure 3 Peak 24-Hour Average PM10 Concentrations
Sacrament o County 1989-2009

Note: The peak 1999 concentration of 141 μ g/m 3 occurred on July 5 th at the Del Paso Manor monitoring site, and was likely impacted by emissions from the Fourth of July fireworks.

D. Maintenance Plan

The Sacramento PM10 Plan includes the followi ng components: attainment emission inventory; maintenance demonstration; co mmitment to continue monitoring network operation; commitment for verification of c ontinued attainment; a contingency plan; and transportation conformity budgets.

1. Attainment Emission Inventory

The Plan must demonstrate that the PM10 standard is attai ned and maintained, despite future growth in the emissions inventory. The emissions inventory is a systematic listing of the sources of air pollutants along with the amount of pollutants emitted from each source or category over a given period of time . The inventory is a critical tool used to indicate trends, measure cont rol efficacy, and evaluate air pollution mitigation. To determine the expected emissions in future years, projected emission inventories incorporate the effects of gr owth and existing regulations on a baseline inventory.
Emission inventories are estima tes of the air pollutant em issions released into the environment – they are not direct ambient c oncentration measurements. However, if the inventory is reviewed in conjunction with the actual poll utant concentrations measured by the monitoring network, proporti onal relationships can be developed to

October 29, 2010 Page 7predict future concentrations of pollutants. This exercise, detailed in the Plan,
demonstrates continued attainment of the standard into the future.

In Sacramento County, the emissions invent ory was analyzed for directly-emitted PM10 and NOx (as a precursor to ammonium nitr ate). The District prepared seasonal emission inventory projec tions for a winter day since 24-hour PM10 average concentrations have historically been the hig hest during this time. The main emissions source types contributing to winter PM10 air quality in the County are secondary ammonium nitrate particles and directly em itted particles from motor vehicle exhaust and wood smoke. Typical wintertime weat her conditions in Sacramento County include high atmospheric stability, lo w wind dispersion, and colder temperatures which are conducive to PM10 pollutant bu ild-up, especially for ammonium nitrate particles.

The Plan used 2008 as the base year from wh ich emission inventor ies were projected into the future for 2012 and 2022. The 2008 emissions inventory is the most recent available. The future years of 2012 and 202 2 bracket the ten-year maintenance period which would start in 2012, the first year after U.S. EPA’s antic ipated approval of redesignation to attainment. The District in ventory updates include the latest point and area source emissions information; ARB’s EMFA C mobile source emission outputs; and planning assumptions in the Sacramento Area Council of Governm ents’ (SACOG) most recent Regional Transportation Plan. Emissi ons reduction credits established prior to 2008 through the regulatory control measures to offset future growth were included in the emissions inventory forecasts, so as not to underestimate futu re emissions for the
maintenance demonstration for the years 2012 and 2022.

2. Maintenance Demonstration

The Act requires the District to show that the PM10 24-hour standard can be maintained for at least 10 years after the redesignat ion request is approved by U.S. EPA. The District analyzed the future mix of sour ces and emission rates and used proportional rollback modeling to show that the emissions would not result in a violation of the standard during the maintenance planning period years, 2012-2022. The premise of proportional rollback is that changes in emissi ons from individual pollution sources over time are directly proportional to the change in associated ambient concentrations due to
that individual source.

The source categories were determined by re ceptor modeling using the Chemical Mass Balance (CMB) model and t he apportionment determined for the winter season in
Sacramento. 2 The PM10 component species were matched to the appropriate emission inventory categories in the roll back analysis. The PM10 and precursor emissions source categories were assumed to vary directly with the matching CMB ambient PM10 speciation categor ies, thereby determining the proportional contributions to overall mass measured at a typical monitor. The emissions inventory projections for these source categories include the effect s of adopted and enforceable controls of ARB,

2 Motallebi, Nehzat. “Wintertime PM 2.5 and PM 10 Source Apportionment at Sacramento California” . Air and Waste Management Association 1999: 25-34.

October 29, 2010 Page 8the District, and other local measures already in place. They also take into account an
additional 1.5 tons of PM10 in 2022 which ca n be added to the invent ory projections for transportati on conformity purposes when the planning horizon for regional transportation plans exceed t he maintenance plan period.

Table 2 shows the 2012 and 2022 projec ted maximum 24-hour average PM10 concentration compared with the base year 2008. The projected changes in peak concentration reflect the projected changes in the emissions inventory. The predicted peak PM10 average daily conc entrations do not exceed 150 μ g/m 3 . This demonstrates
continued attainment of the 24-hour PM10 NAAQS in Sacramento County.

Table 2 Projected Maintenance of 24-hour PM10 NAAQS in Sacramento County

PM10 CMB Analysis Percent of
PM10 Mass Peak
Monitored
Value
Concentration 2012 Projected Peak
Concentration 2022 Projected Peak
Concentration

Source Category (% total) ( μ g/m 3 ) ( μ g/m 3 ) ( μ g/m 3 )

Ammonium Nitrate 24.4% 26.6 23.7 18.1

Motor Vehicles 24.5% 26.7 24.9 20.7

Wood Smoke 17.8% 19.4 18.1 20.0
Fugitive Dust 15.1% 16.5 16.7 18.6

Ammonium Sulfate 1.3% 1.4 2.2 2.4

Unidentified Other 16. 9% 18.4 18.2 18.9

TOTAL PM10 100.0% 109* 104 99

* 109 μ g/m 3 was the peak monitored value in Sacramento Co unty from the three-year period ending in the 2008 base year, using ambient air monitoring data from the T Street monitor in 2006.

3. PM10 Monitoring Network

The District commits to continue PM10 monitoring to verify sustained attainment of the PM10 standard in the County. The existing PM10 monitoring network in Sacramento includes six FRM monitors (Figure 2). The minimum number of monitors required is two
to four monitors based on the population of the Metropolitan Statistical Area containing Sacramento County 3 . Therefore, the curr ent number of monitors within the County is greater than the PM10 monitoring network requirement for the area. The District commits to continue to maintain and operat e a PM10 ambient monitoring network in Sacramento County that meet s or exceeds the minimum monitoring requirements.

3 “Network Design Criteria for Ambient Air Quality Monitoring”, 40 CFR Part 58, Appendix D.

October 29, 2010 Page 94. Verification of Continued Attainment

To verify continued attainment of t he PM10 standards, the District commits to
reevaluate the Plan in accor dance with requirements for main tenance plans found in the Act. The District will review the assumptions and data for the PM10 maintenance
demonstration in 2015 and 2018 to fulfill the verification and tracking requirements. Eight years after the County has been redes ignated to attainment, the District will submit to U.S. EPA the required revision to the Plan demonstrating maintenance of the standard for the following ten-year period. On a regular bas is, the District will continue to analyze PM10 data from FRMs and compare daily PM10 values to the level of the 24-hour standard. This includes tracking t he indicator for triggering the maintenance contingency plan. In addition, the District may also evaluate data from continuous
monitors to aid in the anal ysis of air quality trends.

5. Contingency Plan

The Act requires a maintenance plan to in clude contingency provisions for prompt correction of any PM10 standard violation t hat might occur after the area has been redesignated to attainment. The maintenance plan is not required to contain fully adopted contingency control measur es that will go into effect without further state action as is required in attainment SIPs. Instead, for maintenance plans, the area must have a plan to ensure that contingency actions o ccur once they are triggered. The Plan identifies the specific indicator or tr igger which will be used to determine when contingency provisions should be implemented.

The trigger will be any violation of the 24-hour PM10 standard at a PM10 monitor, verified through filter sampling, weighing and processing. If the data point cannot be flagged and approved as an exceptional event, t hen the District will analyze the event to determine the possible causes and whether applicable emissions reductions from existing measures due to be implemented woul d be sufficient to prevent future PM10 violations. If not, the Distr ict would proceed with select ing specific measures for adoption and implementation to address the PM10 problem. The Plan contains a timeline for this process along with a sugges ted list of reasonably available control measures that may provide cost-effective, particulate matter emissions reductions benefits, according to the circumstanc es associated with the violation.

6. Transportation Conformity Budgets

The Act requires that transportation plans, pr ograms, and projects receiving federal funding or requiring federal approval must be f ound to be fully consistent with the SIP. The federal Transportation Conformity Rule 4 requires SIPs to specify on-road motor vehicle emission budgets (transportation confo rmity budgets) that are consistent with
the attainment and maintenance demonstrations in the SIP. The conformity regulation requires metropolitan planning organizations (MP O) to demonstrate th at emissions from regional transportation plans and programs do not exceed these emissions budgets.

4 The Transportation Conformity Regulati on is found at 40 CFR Parts 51 and 93.

October 29, 2010 Page 10The MPO for Sacramento County is SACOG, whose forecasts of vehicle miles travelled (VMT) were developed from t he MPO’s projections of futu re population, dwelling units, and employment. These VMT forecasts we re used to develop the transportati on conformity budgets for future years for PM10 and NOx using ARB’ s latest on-road
mobile source emission fact or model EMFAC2007 and transporta tion activity data from the August 2009 Metropolitan Transportati on Improvement Program analysis. SACOG’s travel demand model predicts that gr owth in vehicle trips and vehicle miles traveled will be slightly lower than the populati on growth rate for the Sacramento region through 2035.

The transportation conformity budgets refl ect emission reductions from control measures already adopted th rough federal, State and Distric t regulations applied to projected growth in emissions from re-ent rained dust from travel on paved and unpaved roads, vehicular exhaust, and road constructi on. The Transportation Conformity Rule requires that PM10 from construction-rela ted fugitive dust be included in the budget
because it was identified as a contributor to the non-attainment pr oblem. NOx is the only precursor included in the budgets, bec ause ammonium nitrate was shown to contribute significantly to peak PM10 concentrations.

Table 3 shows the proposed transportation conformity budgets for NOx and PM10 average winter day emissions for Sacramento County. If U.S. EPA determines these budgets to be adequate, future transportati on plan amendments and updates in Sacramento County will need to conform to these budgets. SACOG must ensure that the aggregate transportation wintertime emissi ons in the County do not exceed these levels when approving new metropolitan transportation plans and transportation programs, even if the mix of projects changes or grow th increases. These budgets will remain in effect until other budgets are found adequate through approval by U.S. EPA.

Table 3 Motor Vehicle Emission Budgets for Ma intenance of the 24-hour PM10 NAAQS

2008 2012 2022 Sacramento County
NOx PM10 NOx PM 10 NOx PM10 Average Emissions in Tons per Winter Day 50 15 38 15 19 17

For transportation conformity purposes, an addi tional 1.5 tons per day of PM10 were added to the 2022 budget to account for potential emissions increases in dust from paved roads and construction. This accommodat ion is only allowe d for transportation conformity purposes when the emissions forecasts and budgets will be lower than the emissions level needed to provide conti nued maintenance of the standard. These
emissions are also accounted for in the ma intenance emissions inventory forecasts. Figure 4 illustrates that the fu ture NOx emissions inventory is projected to decrease at a considerably faster rate than projected growth in the PM10 inventory, thereby

October 29, 2010 Page 11October 29, 2010 Page 12 maintaining emissions at a level that will not result in a violation of the 24-hour PM10 NAAQS.

Figure 4
PM10 and NOx Precursor Emissions for Sacramento County 1990-2022*

* Data for 1990, 2000, and 2008 are historical, while data for 2012 and 2022 are projections

IV. STAFF RECOMMENDATION

ARB staff has reviewed the Plan prepared by the District and consulted with the District staff during this review. ARB staff concur s with the District’s Plan and finds that the Plan meets all applicable Act r equirements. ARB staff belie ves that implementation of
this Plan will continue to maintain PM10 le vels below the national air quality standard in Sacramento County. Theref ore, ARB staff recommend t hat the Board approve the Sacramento PM10 Plan, includin g the transportation conformi ty budgets for the County,
as a revision to the California SIP for submit tal to U.S. EPA. In addition, ARB staff recommends that the Board appr ove the District’s request to U.S. EPA that Sacramento County be redesignated from nonattainment to attainment fo r the national PM10
standard.