Technical Support Document 

for the

Chico Nonattainment Area (Partial Butte County)

2011 Daily Winter-Time Emissions Inventory 

Base Year 2005-Grown and Controlled in Tons per Day

Submitted to EPA on November 15, 2012 by the California Air Resources Board (CARB)

December 20, 2013
I. Introduction

The purpose of this document is to supplement the technical information provided in the direct 

final federal register notice approving the Chico, CA/Butte County (partial) Planning Area 2011 PM2.5 

Emission Inventory submitted to EPA on November 15, 2012 by the California Air Resources Board 

(CARB) on behalf of the Butte County Air Quality Management District (District or BCAQMD).

1

 Any

questions pertaining to this technical support document (TSD) should be directed to Nancy Levin at 

415-972-3848 or levin.nancy@epa.gov.

II. Procedural Requirements for Adoption and Submittal of SIP Revisions

Sections 110(a)(1) and 110(l) of the Act require states to provide reasonable notice and public 

hearing prior to adoption of SIP revisions. Section 110(k)(1)(B) requires EPA to determine whether a 

SIP submittal is complete within 60 days of receipt. Any plan that we have not affirmatively determined 

to be complete or incomplete will become complete six months after the day of submittal by operation 

of law. A finding of completeness does not approve the submittal as part of the SIP nor does it indicate 

that the submittal is approvable. It does start a 12-month clock for EPA to act on the SIP submittal. See 

CAA section 110(k)(2).

a. Reasonable notice and public hearing

CARB’s submittal documents the public review process followed by Butte County Air Quality 

Management District (BCAQMD) and CARB in adopting the Chico emissions inventory prior to 

submittal to EPA. CARB’s submittal includes a copy of the notice to the public published on August 17, 

2012, announcing a public hearing to be held on September 27, 2012. The notice for the public hearing 

was published in the Chico Enterprise-Record and the Oroville Mercury-Register, newspapers of general 

circulation, on August 17, 2012. The PM2.5 emissions inventory was also made available for viewing on 

the District's website and at the District office on and after August 17, 2012. CARB’s submittal includes 

a letter dated August 17, 2012 from W. James Wagoner, Air Pollution Control Officer to the Board of 

Directors for the BCAQMD recommending that the Board consider comments at the public hearing and 

approve the resolution adopting the proposed PM2.5 emission inventory and forward it to CARB. The 

documentation provides evidence that reasonable notice of a public hearing was provided to the public 

and that a public hearing was conducted prior to adoption. CARB’s submittal documents the adoption of 

the emissions inventory by the BCAQMD Board of Directors. On September 27, 2012, the BCAQMD 

Board of Directors approved the emissions inventory and directed BCAQMD staff to forward the Chico 

emissions inventory to CARB, the Governor of California’s designee for SIP matters.2 CARB’s 

submittal includes a public hearing notice for October 18, 2012,3 a transcript,4 and its October 18, 2012 

 

1 CARB adopted the 2011 PM2.5 Emission Inventory for the Chico nonattainment area in 2012; therefore, CARB refers to it 

as the “2012 PM2.5 Emission Inventory Submittal to the State Implementation Plan for the Chico, CA/Butte County (partial) 

Planning Area.” However, the actual inventory in the CARB submittal (Appendix D) is titled “Chico Nonattainment Area 

(Partial Butte County) 2011 Daily Winter-Time Emissions Inventory (Base Year 2005-Grown and Controlled in Tons Per 

Day.” For purposes of this action, any reference to the 2012 PM2.5 Emissions Inventory is equivalent to the Chico 2011 

winter-time PM2.5 emission inventory. 2 BCAQMD Revised Resolution No. 2012-12, September 27, 2012. 3 CARB Notice of Public Meeting to Consider Approval of the 2012 PM2.5 Emission Inventory Submittal to the State 
Board resolution regarding the Chico emissions inventory.5 On November 15, 2012, CARB submitted 

the inventory to EPA for approval as a revision to the California SIP.

Based on the documentation included in CARB’s submittal, we find that the submittal of the 

Chico, CA/Butte County (partial) Emissions Inventory as a SIP revision satisfies the procedural 

requirements of sections 110(l) of the Act for revising SIPs. 

b. Completeness review

A completeness review allows us to determine if the submittal includes all the necessary items 

and information we need to act on it. We make completeness determinations using criteria we have 

established in 40 CFR part 51, Appendix V. These criteria fall into two categories: administrative 

information and technical support information. The administrative information provides documentation 

that the State has followed basic administrative procedures during the SIP-adoption process and thus we 

have a legally-adopted SIP revision in front of us. The technical support information provides us the 

information we need to determine the impact of the proposed revision on attainment and maintenance of 

the air quality standards. We notify a state of our completeness determination by letter unless the 

submittal becomes complete by operation of law. The Chico, CA/Butte County (partial) Emissions 

Inventory became complete by operation of law on May 15, 2013.

III. Summary of SIP Revisions

The SIP revision submitted by CARB on November 15, 2012 for the Chico/Butte County 

(partial) Planning Area provides a 2011 daily winter-time emissions inventory (“Base Year 2005-Grown 

and Controlled in Tons per Day”), with emission estimates for PM2.5, volatile organic compounds

(VOCs6), nitrogen oxides (NOx), sulfur dioxide (SO2) and ammonia (NH3). The Chico/Butte County 

(partial) Planning Area 2011 daily winter-time emissions inventory for PM2.5 is attached. The federal 

register notice approving this inventory provides a summary of the inventory and the procedural and 

technical basis for approval. In addition to the information provided in the federal register notice, we 

provide information in the following sections IV and V.

IV. Clarification Regarding Calculation of PM2.5 Emissions from Paved Roads 

The 2011 emissions inventory for the Chico nonattainment area submitted by CARB estimates 

PM2.5 emissions from paved roads to be approximately 0.2 tons per day. CARB estimated annual PM10

emissions using the January 2011 AP-42 paved road dust emission factor equation with Californiaspecific silt loadings. Historical days of rain were used for the rainfall adjustment factor. CARB used

California speciation profile #471 to calculate PM2.5 from PM10 (PM2.5 = 0.15 * PM10). 

http://www.arb.ca.gov/ei/speciate/dnldoptvv10001.php#specprof. This differs from the 25% particle size 

fraction for PM2.5/ PM10 given in the AP-42. Emissions estimates used 2008 annualized VMT per 

 

Implementation Plan for the Chico Planning Area, October 1, 2012.

4 Meeting, State of California, Air Resources Board, Sacramento, California, October 18, 2012.

5 CARB Resolution 12-31, October 18, 2012. 6 BCAQMD uses the term Reactive Organic Gas (ROG) rather than VOC. EPA formerly defined the regulated organic 

compounds in outdoor air as ROG. However, EPA later changed that terminology to “VOC.”
average weekday from EMFAC-2011SG, apportioned to road category using 2008 Caltrans HPMS 

travel fractions. The 2008 base year emissions for the Chico nonattainment area were projected to 2011

using centerline miles.7

EPA has reviewed CARB’s methodology for estimating PM2.5 emissions from paved roads and 

determined that the methodology used for calculating the 2008 base year is acceptable; however, use of 

centerline miles to project the 2011 inventory has not been approved by EPA. Because the paved road 

emissions estimate is not being used to create a motor vehicle emissions budget (MVEB) for the Chico

PM2.5 nonattainment area and because the difference in emissions between 2008 and 2011 is expected to 

not be significant, EPA is not requiring at this time that CARB revise the PM2.5 emissions estimate for 

paved roads. If in the future a MVEB and a maintenance plan for the area are submitted to EPA, the 

paved road PM2.5 emissions estimate would need to be derived by a method approved by EPA.

V. Attachment

Chico Nonattainment Area (Partial Butte County) 2011 Daily Winter-time Emission Inventory (Base 

Year 2005-Grown and Controlled in Tons per Day), Appendix D.

 

7 December 11 and 12, 2013 emails from Janet Spencer, CARB, to John Ungvarsky, EPA Region 9,