United States Environmental Protection Agency, Region IX

Air Division

Technical Support Document

for

EPA's Notice of Proposed Rulemaking

for the 

California State Implementation Plan

Northern Sonoma County Air Pollution Control District

Rule 130 – Definitions

AND

Mendocino County Air Quality Management District

Rule 130 – Definitions

Laura Yannayon

March 9, 2011
ii

Table of Contents

Section Page

Introduction 1

PSD Program SIP Revision Submittals 1

Background 1

Rule Summaries 2

Rule Evaluation 2

Section 110(l) of the Act 3

Section 193 of the Act 3

Recommendations 4

Attachments 4
1

Introduction

Part C of title I of the Clean Air Act (CAA or Act) contains the provisions for the 

Prevention of Significant Deterioration (PSD) of air quality in areas designated as “attainment” or 

“unclassifiable” for the national ambient air quality standards (NAAQS). Part D of title I of the 

Act contains the requirements for areas designated “nonattainment” for any of the NAAQS. Both 

parts C and D of the Act require pre-construction permit programs for certain new or modified 

stationary sources of pollutants. The requirements under part C, referred to as “PSD New Source 

Review” (PSD) apply to certain new or modified sources that would be located within attainment 

or unclassifiable areas, and apply to all regulated pollutants, except those pollutants for which an 

area has been designated as “nonattainment.” The requirements under part D, referred to as 

“Nonattainment NSR,” (NSR) apply to certain new or modified sources of nonattainment 

pollutants in nonattainment areas. Collectively, the pre-construction permit requirements related 

to PSD and Nonattainment NSR are commonly referred to simply as “NSR.” Both of these 

programs apply to “major” stationary sources and “major modifications” as those terms are 

defined in 40 CFR Part 51, Subpart I. In addition to the regulation of major stationary sources, 

states are also required to adopt a program to provide for the regulation of the construction and 

modification of minor stationary sources and minor modifications at major sources, to assure that 

the NAAQS are achieved. These pre-construction requirements are commonly referred to as 

“minor NSR.”

PSD Program SIP Revision Submittals

Rule 130 –Definitions was adopted by the Northern Sonoma County Air Pollution Control 

District (NSCAPCD or District) on December 14, 2010. Rule 130 –Definitions was adopted by 

the Mendocino County Air Quality Management District (MCAQMD or District) on February 15, 

2011. The California Air Resources Board (ARB) submitted both rules to EPA by a letter dated 

February 28, 2010. ARB is the governor’s designee for submitting official revisions of the 

California State Implementation Plan (SIP) to EPA. Previous versions of Rule 130 are currently 

approved into the SIP for both Districts. For NSCAPCD and MCAQMD, Rule 130 was last 

approved into the SIP on February 9, 1999 and July 31, 1998, respectively (See 64 FR 6223 and 63 

FR 40830). There are no other pending submittals of these rules.

Background

Both the NSCAPCD and MCAQMD are currently designated as attainment or 

unclassifiable for all NAAQS, and are therefore required to adopt and maintain a SIP-approved 

PSD permit program, CAA Section 161. In both Districts, a combination of SIP approved rules 

make up the PSD permit program, including Rules 130 – Definitions, 200 – Permit Requirements, 

220 – New Source Review Standards, and 260 – Exclusions. 
2

The submitted revisions to Rule 130 – Definitions are being evaluated together in this TSD 

because both the existing SIP rules and proposed revisions are very similar. In each case, the 

District has revised Rule 130 to provide new and revised definitions in order to ensure consistency

with CAA requirements for PSD programs. The specific changes are discussed below in the Rule 

Evaluation section of this document. 

Rule Summaries

Mendocino Rule 130 – Definitions 

Rule 130 defines various terms used throughout the District’s Regulations. In particular it 

provides definitions of several key terms related to the PSD program. In this revision, the District 

has added new definitions for the terms Greenhouse Gases, PM10, and PM2.5, and revised the 

definitions for the terms Precursor, Prevention of Significant Deterioration (PSD) Increment, and 

Significant. The District also made other minor technical corrections. The purpose of these 

changes was to make the terms consistent with the current definitions contained in EPA PSD 

regulations codified in 40 CFR 51.166. 

Northern Sonoma Rule 130 – Definitions 

Rule 130 defines various terms used throughout the District’s Regulations. In particular it 

provides definitions of several key terms related to the PSD program. In this revision, the District 

has added new definitions for the terms Greenhouse Gases, PM10, and PM2.5, and revised the 

definitions for the terms Precursor, Prevention of Significant Deterioration (PSD) Increment, and 

Significant. The District also made other minor technical corrections. The purpose of these 

changes was to make the terms consistent with the current definitions contained in EPA PSD 

regulations codified in 40 CFR 51.166. 

Rule Evaluation

For this TSD, we have reviewed each Rule 130 SIP submittal to ensure the new and revised 

definitions meet the requirements of section 110 and part C of title I of the Act and implementing 

regulations at 40 CFR 51.166. This TSD describes the rule revisions and the reasons for our 

proposed action on the Rule 130 submittals. Since both Districts have made identical revisions to 

their rules, the changes are only discussed once below. The Act requires all States with 

attainment or unclassifiable areas to submit a PSD program that contains specific PSD program 

provisions. Since the submitted rules only consist of definitions, our evaluation focuses on 

whether the definitions contain language which is either identical or equivalent to that found in 40 

CFR 51.100 and 51.166. 

New Definitions

 A new definition has been added for Greenhouse Gases (GHG). This term is defined 

within the definition of the term “subject to regulation” in 40 CFR 51.166 (b)(48). 
3

The District’s definition is equivalent in that it includes the same six gases as EPA’s 

definition of GHGs.

 A new definition has been added for PM10, and PM2.5. These definitions are consistent 

with the definitions of these NAAQS pollutants found in 40 CFR 51.100(qq), 50.6, 

50.7, and 50.13. 

Revised Definitions

 The current definition for the term Precursor has been revised to specify that VOC and 

NOx are ozone precursors, and that NOx and SOX are PM2.5 precursors. These changes 

make this definition consistent with the precursors identified by the Administrator, 

within the definition of “regulated NSR pollutant” in 40 CFR 51.166 (b)(49). 

 The current definition for the term Prevention of Significant Deterioration (PSD) 

Increment has been revised to update the allowable increments for PM10, and add the 

allowable increments for PM2.5, consistent with the values listed in 40 CFR 51.166(c) –

Ambient air increments and other measures. 

 The current definition for the term Significant has been revised to add significant 

emission rate thresholds for PM2.5 and municipal waste combustors. These changes 

make this definition consistent with the definition of “significant,” in 40 CFR 51.166 

(b)(23). 

Summary

As discussed above, each of the new or revised terms is consistent with the applicable

definitions for these terms in 40 CFR 51.100 and 51.166 and part 50. 

Section 110(l) of the Act

Section 110(l) of the Act prohibits EPA from approving any revision of a SIP if the 

revision would interfere with any applicable requirement concerning attainment and reasonable 

further progress, or any other applicable requirement of the Act. The approval of these rules 

would strengthen the applicable SIP by adding and updating terms that establish applicability and

evaluation criteria for pollutants subject to the PSD program. The rules do not represent any type 

of relaxation and therefore would not interfere with attainment and reasonable further progress, 

and thus are approvable under Section 110(l) of the Act. 

Section 193 of the Act

Section 193 of the Act, which was added by the Clean Air Act Amendments of 1990, only 

applies to control requirements in nonattainment areas. Neither the NSCAPCD and MCAQMD 
4

are classified nonattainment for any NAAQS; therefore Section 193 does not apply to this 

rulemaking action.

Recommendations

Pursuant to section 110(k)(3) of the Act, we recommend full approval of the submitted

rules. We recommend approval of the submitted rules based on our determination that the rules

comply with applicable statutory and regulatory provisions, including section 110(a)(2)(C) and 

part C of title I of the Act. In support of this recommendation, we have concluded that our 

approval of Rule 130 (for each District) complies with section 110(l) of the Act because the rules 

do not represent a relaxation of any current SIP provision. If we finalize this action as proposed, 

our approval would be codified through revisions to 40 CFR 52.220 (identification of plan).

Attachments

1) Submitted NSCAPCD Rule 130 and MCAQMD Rule 130.

2) SIP Approved NSCAPCD Rule 130 and MCAQMD Rule 130.