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 

as Submitted by the California Air Resources Board 

EPA’s analysis of 

Ventura County Air Pollution Control District’s 

Rule 23 – Exemptions from Permit 

March 12, 2015 

Prepared by Larry Maurin and Jefferson Wehling 

Approved by Gerardo Rios 

 
1 

Ventura County Air Pollution Control District (VCAPCD or District) 

Submitted Rule 

• Rule 23, Exemptions from Permit, was originally adopted on October 22, 1968. The rule 

has been revised seven times since the last SIP-approved version of the rule was 

approved by EPA on December 7, 2000. See Table 1 below for a list of the adoption and 

submittal dates for recent revisions of Rule 23. While each of these revisions was 

submitted to EPA for inclusion in the SIP, EPA has not taken action on any of these 

submittals. The current rule revision was adopted on November 12, 2013 and submitted 

by the California Air Resources Board (CARB) on May 13, 2014. While EPA can only 

take action on the most current submittal, we list below all of the changes made since 

Rule 23 was last SIP approved.

Table 1. Adoption and corresponding submittal dates 

of VCAPCD Rule 23 revisions

Adoption Date Submittal Date 

November 11, 2003 April 26, 2005 

April 13, 2004 July 19, 2004 

October 12, 2004 April 26, 2005 

September 12, 2006 December 29, 2006 

April 8, 2008 January 10, 2010 

April 12, 2011 September 27, 2011 

November 12, 2013 May 13, 2014 

Applicable State Implementation Plan (SIP) Rule 

• Rule 23, Exemptions from Permit – The SIP approved version of this rule was revised on 

July 9, 1996, submitted on October 18, 1996, and approved into the SIP on December 7, 

2000 (65 FR 76567).

Background 

Ventura County is currently classified as a serious nonattainment area for the 2008 and 1997 

federal 8-hour ozone standards and attainment or unclassifiable for all other National Ambient 

Air Quality Standards (NAAQS). 

Agricultural operations are a significant source of air pollution throughout the state of California, 

including Ventura County. Historically, agricultural operations had been exempted from many 

regulatory requirements, including the need for air pollution permits. On September 22, 2003, 

California Senate Bill 700 (SB 700) became law and removed the blanket permitting exemption 

for agricultural sources provided under California Health & Safety Code (CH&SC) Section 

42310(e) and subjected large agricultural sources to various permit requirements for the first 

time. 
2 

VCAPCD was required to amend and adopt a number of rules to comply with the requirements 

of SB 700, including revisions to Rule 23. The state law also requires permits and emission 

mitigation for Large Confined Animal Facilities (LCAF) as defined by CARB. 

Purposes of Rule and Descriptions of Rule Amendments

Rule 23 – Exemptions from Permit was originally developed as part of the District’s New Source 

Review (NSR) permitting program. The rule identifies processes, articles, machines, equipment, 

or other contrivances for which an Authority to Construct (ATC) and/or Permit to Operate (PTO) 

is not required. While EPA can only act upon the most recent submitted version of Rule 23, we 

have reviewed all of the changes made since EPA last approved Rule 23 into the Ventura County 

portion of the California SIP. EPA has evaluated the following list of revisions made to the 

existing SIP approved version of Rule 23, compared with the submitted version of Rule 23. 

1. Existing Rule 23 – Exemptions from Permit was revised as follows: 

• A.4 – The exemption has been revised by adding new language to limit applicability of 

the exemption to safety flares rated at less than one million BTU per hour. 

• B.4 – The exemption has been revised by adding new language to clarify that the listed 

types of equipment are exempted even if they are using “metalworking fluids, direct 

contact lubricants, or vanishing oils that are ‘Super Compliant Materials’ containing 50 

grams ROC per liter of material or less, including, but not limited to, metal protecting 

(corrosion inhibitor application equipment) and metal treating quench tanks...”. New 

language was added to clarify that metal forging operations are still subject to permit 

requirements. 

In addition, language was added to exempt the following specific types of equipment 

using any metalworking fluid regardless of the ROC content of the fluid being used: 

a. Lapping 

b. Sinker Electrical Discharge Machining 

c. Carbide grinding machine tools where the machine tool manufacturer specifies 

the viscosity of the fluid 

d. Machining of aluminum or magnesium in single or multiple spindle automatic 

machines 

• D.1 – The exemption for aircraft has been moved to section D.2. 

• D.2 – The exemption has been revised to further specify which type of vehicles are 

exempt from permitting requirements including locomotives, aircraft, marine vessels, and 

recreational watercraft used to transport passengers or freight. Language was also added 

to clarify that any equipment mounted on a locomotive, aircraft or marine vessel that 

would otherwise require a permit under the provisions of the District’s Rules and 

Regulations is not exempted under this provision. 

• D.6 – The exemption has been revised to limit applicability to only internal combustion 

engines with a maximum “continuous” design power rating of less than 50 brake 

horsepower. An exemption was added for gas turbines with a rated full load output of less 

than 0.30 megawatts (300 kilowatts) at ISO Standard Day Conditions. 

• D.7 – The exemption has been reorganized, reworded, and further clarified, and now 

reads as follows: 

“Emergency internal combustion engines, as follows:
3 

a. Spark-ignited internal combustion engines used exclusively for the emergency 

pumping of water for either fire protection or flood relief. The engines may either 

drive pumps directly or generate electricity to drive pumps. Such engines may be 

operated for engine maintenance, 

b. Spark-ignited emergency internal combustion engines used only when 

electrical power line or natural gas service fails. Such engines may be operated for 

engine maintenance, and 

c. Portable engines used for emergency purposes. An engine powering a generator 

connected to a facility's electrical grid in preparation for a future emergency shall 

not be considered a portable emergency engine.” 

• F.6 – The exemption for solvent cleaning equipment or operations listed under F.6 in the 

approved SIP has been removed since it expired on July 9, 1997. The unrelated 

exemption for non-refillable aerosol cans, formerly listed under F.10.b and d, F.11.a and 

b, F.12, F.13, F.15, F.20, and F.22 in the approved SIP version of Rule 23, have now 

been combined and listed under F.6. 

• F.10 – The exemption was expanded to include general cleaning operations rather than 

only solvent cleaning operations, as follows: 

a. The exemption was revised from “cleaning agents that contain two percent or 

less organic solvent, by weight, as used or applied” to “cleaning agents certified 

by the SCAQMD as Clean Air Solvents.” The term “Clean Air Solvents” is not 

defined in any Ventura rule, but is defined in South Coast AQMD Rule 102, 

Definitions, which is SIP approved. 

b. The exemption was revised from “Non-refillable aerosol cleaning products” to 

“Cleaning agents that contain no more than 25 grams per liter of ROC as used or 

applied, and no more than 5 percent by weight combined of methylene chloride, 

perchloroethylene, trichloroethylene, 1,1,1-trichloroethane, carbon tetrachloride, 

and chloroform.” 

c. No changes were made to exemption F.10.c. 

d. The exemption has been revised to specify “solvent cleaning operations, 

including cold cleaners, vapor degreasers, wipe cleaning, dip cleaning and flush 

cleaning,” rather than “cleaning activities.” In addition the exemption has been 

revised from “cleaning agents that contain two percent or less organic solvent by 

weight as used or applied, aerosol products, and cold cleaners included in 

subsection c above” to “activities exempted by subsections a, b, and c, above.” 

• F.12 – The exemption was clarified to include ‘sealant’ operations in addition to adhesive 

operations. 

• F.14 – The usage allowed by the exemption was annualized by revising “20 gallons of 

polyester resin materials each month” to read “240 gallons of polyester resin materials 

over a rolling period of 12 consecutive calendar months.” 

• F.23 – The exemption has been narrowed to limit applicability to soil aeration projects 

for soils contaminated with gasoline, diesel fuel, or jet fuel. 

• J.10 – The exemption has been revised to apply only to cooling towers and ponds that are 

not in contact with contaminated process water. 

• J.12 – The exemption was reworded to update the names of responsible regulatory 

agencies. The former agency “Advisory Council on Atomic Energy Development and 

Radiation Protection” has now been replaced by the “California Energy Commission and 
4 

the California Department of Health Services.” The “United States Atomic Energy 

Commission” is now the “United States Nuclear Regulatory Commission.” 

2. The following new exemptions were added to Rule 23 and are listed by categorization: 

A. Equipment or processes that are exempted from a corresponding VCAPCD 

prohibitory rule which requires emission controls 

• D.6 – Gas turbines with a rated full load output of less than 0.30 megawatts (300 

kilowatts) at ISO Standard Day Conditions (Rule 73.23).

• F.20 – Oilfield wastewater sumps, pits, or ponds, where the ROC content of the 

wastewater entering the sump, pit or pond is less than 5 milligrams per liter (Rule 

71.4). 

B. Sources with insignificant emissions 

• E.6 – Smokehouses for food preparation in which the maximum horizontal inside 

cross-sectional area does not exceed 2 square meters (21.5 square feet). 

• E.7 – Smokehouses that use liquid smoke exclusively and are completely enclosed. 

To qualify, a smokehouse must vent to neither a control device nor the atmosphere. 

• E.8 – Confection cookers where products are edible and intended for human 

consumption. 

• E.9 – Grinding, blending or packaging equipment used exclusively for tea, cocoa, 

roasted coffee, flavor, fragrance extraction, dried flowers, or spices, and control 

equipment used exclusively with such equipment, provided no organic solvents are 

used. 

• E.10 – Equipment used for the purpose of preparing food for human consumption, 

excluding conveyorized charbroilers and coffee roasting equipment with a maximum 

capacity of greater than 25 pounds, in either eating establishments or retail 

establishments. 

• E.11 – Equipment used to produce noodles, macaroni, pasta, food mixes or drink 

mixes, and control equipment used exclusively with such equipment, where products 

are edible and intended for human consumption, provided no organic solvents are 

used. Not included are storage bins located outside buildings and combustion 

equipment not exempt pursuant to Subsection C.1 of this rule. 

• E.12 – Non-retail cooking kettles, excluding deep-frying equipment, where the 

product is edible and intended for human consumption. 

• E.13 – Coffee roasting equipment with a maximum capacity of 25 pounds or less. 

• E.14 – Ovens, mixers, scales, blenders used in bakeries, and control equipment used 

exclusively with such equipment, where products are edible and intended for human 

consumption and where the total production is less than 1,000 pounds of product per 

operating day. 

• I.13 – Wax burnout kilns with an internal volume of 0.2 cubic meters (7.0 cubic feet) 

or less and a rated capacity of less than one million BTUs per hour. 

• J.3 – Fuel cells that use phosphoric acid, molten carbonate, proton exchange 

membrane or solid oxide technologies. 
5 

• J.15 – Equipment used exclusively to generate ozone and associated ozone 

destruction equipment for the treatment of cooling tower water or for water treatment 

processes. 

C. Equipment or operations which are not subject to NSR program requirements 

because they are not stationary sources 

• D.9 – Portable internal combustion engines, including any turbines qualified as 

military technical support equipment under Health and Safety Code Section 41754, 

used pursuant to registration in the California Statewide Portable Engine Registration 

Program (PERP) under Health and Safety Code Section 41753. 

D. Agricultural source exemptions added pursuant to SB 700 and CARB definition of 

LCAF (CH&SC Section 86500) 

• J.16 – This provision was added to read as follows:

Emission units used exclusively in agricultural operations, except where the total 

actual annual emissions, excluding fugitive PM10 emissions, from an agricultural 

source is equal to or greater than 50 percent of any of the following federal major 

source thresholds:

Pollutant Threshold (Tons Per Year) 

 Any single HAP 10 

Combination of HAPs 25 

CO, PM10, or SOx 100 

Greenhouse Gases (CO2e) (effective July 1, 2011) 100,000 

Greenhouse Gases (CO2e) (until July 1, 2011) No Applicable Threshold 

Attainment / Nonattainment Threshold (TPY) 

Classification (Ozone) (ROC, NOx) 

Attainment, Marginal, or Moderate 100 

Serious 50 

Severe 25 

Extreme 10 

This provision shall not exempt any large confined animal facility or any major 

source or any major modification to a major source required to be issued a permit 

pursuant to Title I (42 U.S.C. Sec 7401 et seq.) or Title V (42 U.S.C. Sec 7661 et 

seq.) For the purpose of this subsection, agricultural operations are operations 

conducted in the raising of fowl or animals or the production of the products of the 

soil, including crops, orchard fruits, trees, vines, rose bushes, ornamental plants, 

floricultural crops, and other horticultural crops. An agricultural source includes all 

emissions units that are not exempt pursuant to other provisions of this rule which are 

used in agricultural operations located on contiguous property under common 

ownership or control. 
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For the purposes of this subsection a “large confined animal facility” is defined as 

follows: 

(i) 1,000 milk-producing dairy cows; 

(ii) 3,500 beef cattle; 

(iii) 7,500 calves, heifers or other cattle; 

(iv) 650,000 chickens other than laying hens; 

(v) 650,000 laying hens; 

(vi) 650,000 ducks; 

(vii) 100,000 turkeys; 

(viii) 3,000 swine; 

(ix) 2,500 horses; 

(x) 15,000 sheep, lambs, or goats; or 

(xi) 30,000 rabbits or other animals. 

Rule Evaluation 

EPA is primarily using the following three criteria to evaluate Rule 23. 

1. Enforceability – Clean Air Act (CAA) Section 110(a)(2)(A) requires that 

regulations submitted to EPA for SIP approval must be clear and legally 

enforceable. 

2. New Source Review Program Requirements – 40 CFR part 51, Subpart I – 

Review of New Sources and Modifications, which allows permit authorities to 

exempt small sources from permit requirements if regulating those sources is not 

necessary for the area to attain or maintain any NAAQS. 

3. Anti-Backsliding − CAA Section 110(l) restricts certain SIP revisions that would 

relax existing SIP-approved requirements if they would interfere with the 

District’s ability to attain or maintain attainment of a NAAQS. 

The Clean Air Act through 40 CFR 51.160 – 51.165 requires States (Districts in California) to 

establish a program for preconstruction review of new or modified major stationary sources 

(New Source Review – NSR), including procedures for authorizing construction of such sources. 

(40 CFR 51.160(a)). The District issues permits referred to as Authority to Construct (ATC) to 

authorize the construction of new and modified sources. 

Rules 10 – Permits Required, 23 – Exemptions from Permit, and 26 – New Source Review

are the major components of VCAPCD’s NSR program. Rule 10 requires sources to 

obtain an ATC for construction and PTO for operation of sources as part of NSR. Rule 23 

identifies what sources are not required to obtain an ATC and/or PTO. Rule 26 

establishes the requirements for new and modified stationary sources to ensure that the 

operation of such sources does not interfere with the attainment or maintenance of 

Ambient Air Quality Standards. Under the federal NSR program, all major stationary 

sources (ones with potential emissions over specified thresholds) are required to obtain an 

ATC prior to construction. This technical support document discusses only Rule 23 

which we are evaluating for approval into the Ventura County portion of the California 

SIP. 
7 

Pursuant to 40 CFR 51.160(e), a district has flexibility to determine which types and sizes 

of minor sources (non-major) are required to obtain an ATC as necessary to ensure 

attainment and maintenance of the NAAQS in accordance with their SIP approved 

attainment plan. 

Section 110(l) states: “Each revision to an implementation plan submitted by a State under this 

chapter shall be adopted by such State after reasonable notice and public hearing. The 

Administrator shall not approve a revision of a plan if the revision would interfere with any 

applicable requirement concerning attainment and reasonable further progress (as defined in 

Section 7501 of this title), or any other applicable requirement of this chapter.” With respect to 

the procedural requirements of CAA Section 110(l), based on our review of the public process 

documentation included in the May 13, 2014 submittal, we find that VCAPCD has provided 

sufficient evidence of public notice and opportunity for comment and public hearings prior to 

adoption and submittal of Rule 23. The remaining Section 110(l) criteria are evaluated below. 

Rule 23 – Exemptions from Permit – Numerous revisions have been made to Rule 23, 

which are described above in the section titled “Purposes of Rule and Descriptions of

Rule Amendments”. These revisions include not only administrative changes to the rule 

such as re-numbering and updating the format, but also the addition of general 

provisions, revisions, deletions and additions to the types of equipment exempted from 

permit requirements. The administrative changes to the rule generally provide additional 

clarity to the rule and do not affect the stringency of the District’s NSR program and 

therefore do not require further evaluation. The new general provisions, revisions, and 

additions to the exemptions found in the current SIP-approved rule version of Rule 23 are 

evaluated below as necessary to further explain why the changes are acceptable. 

1. Revision of Existing Rule 23 Exemptions 

• The revision to section A.4 puts a new restriction on maximum exempt flare capacity. 

This revision narrows the existing exemption, thus providing a strengthening of the SIP. 

We find this revision acceptable. 

• The exemption in section B.4 for equipment used in various types of machining of 

various materials was revised in three significant ways. First new language was added to 

clarify that the existing exemption applies to any of the equipment used with 

metalworking fluids, direct contact lubricants, or vanishing oils, if the materials are Super 

Compliant Materials containing 50 grams ROC per liter of material or less. Second, new 

language was added to clarify that this new ROC content limit does not apply to any 

metalworking fluid, if used in lapping, sinker electrical discharge machining, carbide 

grinding machine tools where the machine tool manufacturer specifies the viscosity of the 

fluid, and machining of aluminum or magnesium in single or multiple spindle automatic 

machines. Third, new language was added to clarify that forging operations remain 

subject to permit requirements. Revisions place restrictions on the ROC content of these 

fluids when used by certain types of equipment. Since the existing exemption had no 

limits on fluids, lubricants, or oils used with these types of equipment, the revisions 

narrow the existing exemption and provides a strengthening of the SIP. Therefore we find 

these revisions acceptable. 
8 

• The revisions to section D.2 more specifically identify the type of vehicles which are 

exempt from permit requirements to include locomotives, aircraft, marine vessels and 

recreational watercraft which are not considered stationary sources under the NSR 

program. The new language also clarifies that any equipment mounted on these vehicles 

that would otherwise require a permit is not exempted. These revisions do not relax the 

requirements of the existing SIP because they merely clarify which “vehicles” are exempt 

from permit requirements. 

• The revisions to section F.6 consolidate exemptions of nonrefillable aerosol cans 

formerly listed under F.10.b and d, F.11.a and b, F.12, F.13, F.15, F.20, and F.22 in the 

approved SIP version of Rule 23. EPA notes that the existing exemptions for 

nonrefillable aerosol cans are also exempted from corresponding VCAPCD prohibitory 

Rules 74.02, 74.03, 74.12, 74.13, 74.18, 74.24, 74.24.1, or 74.30. Consolidation of these 

exemptions make the SIP no less stringent. 

• Several revisions were made to section F.10, which provides exemptions for specified 

cleaning operations and materials. F.10.a changes the basis for exempting cleaning agents 

from those containing 2% or less organic solvent by weight to any cleaning agent 

certified by South Coast Air Quality Management District (SCAQMD) as a Clean Air 

Solvent. A Clean Air Solvent is defined in SCAQMD Rule 102 as a VOC-containing 

material used to perform solvent cleaning, solvent finishing, or surface preparation 

operations or activities which: 

a. Contains no more than twenty-five (25) grams of VOC per liter of material, as 

applied; 

b. Has a VOC composite partial vapor pressure less than 5 mm Hg at 20°C 

(68°F); 

c. Reacts to form ozone at a rate not exceeding that of toluene; 

d. Contains no compounds classified as Hazardous Air Pollutants (HAPs) by the 

Federal Clean Air Act, or Ozone Depleting Compounds (ODCs) and Global 

Warming Compounds (GWCs) as defined by the District; and 

e. Has been certified by the District to meet the criteria stated in (a) through (d) 

according to test methods and procedures approved by the District. 

 Pursuant to the definition in SCAQMD Rule 102, a Clean Air Solvent Certificate is a 

certificate issued by the District to a manufacturer, distributor, or facility for a specified 

product or class of products that meets the criteria for a Clean Air Solvent. 

Section F.10.b adds additional restrictions to the exemption for cleaning agents consistent 

with the exemption provided in VCAPCD Rule 74.06 – Surface Cleaning and 

Degreasing. In addition to a limit on VOC content of no more than 25g/L, a cleaning 

agent must also contain no more than 5 percent by weight combined of methylene 

chloride, perchloroethylene, trichloroethylene, 1,1,1-trichloroethane, carbon tetrachloride, 

and chloroform. These additional requirements for exemption from permit make the SIP 

more stringent. F10.d has also been modified to further specify which cleaning activities 

are exempt from permit requirements. This revision serves to clarify the exemption. 

• F.12 has been revised to expand the existing exemption for adhesive operations to also 

include sealants operations. In Rule 74.20 – Adhesives and Sealants, sealants are defined 

as a subset of adhesives. Therefore, the addition of the term “sealant” to the exemption 

clarifies the types of adhesive operations which are exempt from permit requirements. 

This revision clarifies the existing exemption and has no effect on its stringency. 
9 

• F.14 has been revised to allow exempt polyester resin operations to use up to 240 gallons 

of polyester resin materials over a rolling period of 12 consecutive calendar months 

rather than 20 gallons each month. According to the District, the repair of a large boat 

may require more than 20 gallons of materials in a single month. Thus the exemption has 

been revised to provide boatyards flexibility to make an occasional large repair, but still 

maintain an equivalent annual usage limit. This revision has no effect on stringency of 

the rule because it simply annualizes the existing exempt usage limits of polyester resin 

materials. 

• F.23 was revised to limit applicability only to aeration of soils contaminated with 

gasoline, diesel fuel, or jet fuel. This revision narrows the existing exemption, thus 

providing a strengthening of the SIP. We find this revision acceptable. In addition, the 

cross-references to the exempt provisions listed in subsection C of Rule 74.29 – Soil 

Decontamination Operations have been updated to eliminate the exemption for projects 

located further than 1,000 feet from the outer boundary of a school and with emissions of 

less than 200 pounds of ROCs per rolling twelve month period. According to VCAPCD, 

this exemption was deleted because it has never been used. This revision has no effect on 

the stringency of the exemption because it simply updates the cross-references to another 

District rule. 

All of the revisions made to existing exemptions in Rule 23 are acceptable in accordance 

with the three rule evaluation criteria outlined above. The revisions either clarify existing 

exemptions, having no effect on stringency, or significantly narrow an existing exemption. In 

no case is there a significant relaxation of any exemption which has been revised in Rule 23. 

2. Addition of New Exemptions not included in current SIP-approved rule 

In the “Purpose of Rule and Description of Rule Amendments” section of this document we 

grouped all new exemptions into 4 groups according to the basis for the exemption. The 

discussion of the impact and approvability of these changes are provided below utilizing the 

same 4 groupings. 

A. Equipment or processes that are exempted from a corresponding VCAPCD 

prohibitory rule which requires emission controls 

Under this grouping we have included equipment or processes that are exempted from 

prohibitory rule requirements due to output, size, low emissions or type of fuel used. 

These exemptions in such rules are typically based on a district’s determination, made 

during the rule adoption process, that it is not reasonable to subject such sources to 

control requirements because it is not cost-effective. EPA considers the District’s 

decision to establish permit exemption thresholds that mirror prohibitory rule 

applicability or exemption thresholds to be reasonable because these emission units are 

not subject to any emission control requirements. Because no additional emission 

reductions would occur if such sources were required to obtain an ATC, the addition of 

these exemptions has no effect on the District’s ability to attain or maintain any NAAQS 

and the exemptions are therefore approvable. 

B. Sources that have insignificant or de minimus emissions 
10 

After review of the sources listed in this category, EPA concurs with the District that the 

listed sources have very low levels of emissions due to the type of process (e.g. 

mechanical or physical processes) and that they can be classified as insignificant 

emissions and/or they are equipment or activities that have been identified by EPA as 

trivial in EPA’s guidance document entitled “EPA White Paper for Streamlined 

Development of Part 70 Permit Applications” (See Attachment #11). Exempting these 

types of sources from permit requirements is consistent with the flexibility allowed to 

states to exempt from permit requirements sources that are not likely to interfere with 

their ability to attain and maintain any NAAQS. See 40 CFR 51.160(e). 

C. Equipment or operations which are not subject to NSR program requirements 

because they are not stationary sources 

40 CFR 51.160(a) states that a NSR program must apply to “the construction or 

modification of a facility, building, structure or installation....” NSR programs do not 

apply to mobile sources (including portable equipment) or other activities that have been 

specifically excluded such as routine repairs or maintenance. Therefore EPA finds that 

the new exemptions for equipment not subject to the NSR program is acceptable. 

D. Agricultural source exemptions added pursuant to SB 700 and CARB definition of 

Large Confined Animal Facility (LCAF) (CH&SC Section 86500) 

Before SB 700 was adopted in 2003, air districts in California were prohibited by state 

law from requiring permits for pollutants emitted from agricultural sources. Because this 

prohibition existed in state law (CH&SC 42310(e)), most districts did not provide 

specific exemptions for agricultural sources from the requirement to obtain an ATC 

and/or PTO in their local permit exemption rule. SB 700 ended the prohibition contained 

in CH&SC 42310(e). As part of this rule revision, the District has added new language to 

implement revised state law under SB 700 by adding the following specific exemption 

thresholds for agricultural sources: 

• J.16 provides a new exemption for emission units used exclusively in agricultural 

operations. This exemption applies only to such units where the total actual annual 

emissions, excluding fugitive PM10 emissions, from an agricultural source is less than 

50 percent of any of the listed federal major source thresholds. Language is included 

to clarify that this exemption does not apply to any LCAF (as defined in the 

provision) or any federal major source or major modification to a major source which 

requires a permit pursuant to Title I or Title V of the Clean Air Act. The thresholds 

for what constitutes a LCAF are based on the definition developed by CARB under 

state law. CARB based the definition of LCAF on the number of animals housed 

daily at the facility and mainly focused the determination on air emission impacts 

from these sources in the San Joaquin Valley and South Coast (Los Angeles region) 

which are both extreme nonattainment areas for ozone and for which the major source 

threshold is 10 tpy for ozone precursors (VOC and NOx). As such, the size cuts 

established in CARB’s LCAF definition correspond to VOC emissions (i.e., the 

predominant ozone precursor emitted by such facilities) of less than 10 tpy. See page 
11 

33 of CARB’s Staff Report: Initial Statement of Reasons for Rulemaking, release 

date May 6, 2005, prepared in connection with developing the definition for LCAF. 

Based on these limitations, we are proposing to find that the new minor agricultural 

source exemption satisfies CAA Section 110(a)(2) and 40 CFR 51.160(e). The new 

exemption is enforceable and consistent with VCAPCD’s flexibility to identify which 

sources are subject to and/or exempt from permit requirements. 

CAA Section 110(l) Evaluation of Section J.16 of Rule 23 

We have also evaluated section J.16 of Rule 23 for consistency with CAA Section 110(l). 

The new permitting exemption for certain new or modified minor agricultural sources 

would allow such new sources and modifications to avoid new source review, and the 

related air quality evaluations and control technology review. However, we find that the 

exemption would not interfere with reasonable further progress and attainment of any of 

the NAAQS in Ventura County or any other applicable requirement of the CAA. As 

discussed further in the paragraphs that follow, this is because of the limited nature of the 

exemption, the presence of other regulatory controls for exempt agricultural sources, the 

low background concentrations for the NAAQS pollutants in Ventura County other than 

ozone, and the fact that the submitted ozone plan for the county does not rely on NSR 

controls for minor agricultural sources and that the downward trend in ozone precursor 

emissions in Ventura County is predicted to continue well into the future. 

First, with respect to the limited nature of the exemption, we note that, as to ozone 

precursors, the exemption applies only to new or modified agricultural sources with 

actual emissions less than 12.5 tpy (including fugitive emissions) based on EPA’s “antibacksliding” regulations governing the transition from the 1-hour ozone NAAQS to the 

1997 8-hour ozone NAAQS and under which NSR requirements linked to the area’s 

classification for the now-revoked 1-hour ozone continue to apply in areas, such as 

Ventura County, that are designated nonattainment for the 1997 8-hour ozone standard. 

Ventura County’s classification for the now-revoked 1-hour ozone NAAQS is “severe,” 

and 50% of the corresponding major source threshold (25 tpy) is 12.5 tpy. 

The exemption is further limited by excluding LCAF that are defined in terms that would 

generally trigger the permit requirement at emissions levels less than 12.5 tpy of VOC. 

For instance, for dairy facilities, LCAF is defined as 1,000 milk-producing dairy cows 

and, based on CARB estimates presented in the CARB staff report cited above, a 1,000-

cow dairy corresponds to VOC emissions of approximately 7.2 tpy. Thus, the emissions 

from exempt new or modified minor agricultural sources would be minimal and the 

foregone emissions reductions that might theoretically been applied to such sources 

would be even less. 
12 

Second, certain exempt new or modified agricultural sources would be subject to controls 

in other regulations that would serve to limit the potential for significant emissions 

impacts from such sources. These regulations include Ventura County APCD regulation 

V (“Orchard Heaters”), including 5 rules approved at different times but the more recent 

of which (Rule 80 – “Permits”) was approved by EPA at 52 FR 12522 (April 17, 1987); 

Ventura County APCD Rule 56 (“Open Burning”), last approved by EPA at 70 FR 8516 

(70 FR February 22, 2005); and the California Department of Pesticide Regulation’s 

Fumigant Regulations, last approved by EPA at 77 FR 65294 (October 26, 2012). 

Third, with respect to the “criteria” or “NAAQS” pollutants other than ozone, Ventura 

County is designated as “attainment” or “unclassifiable,” see 40 CFR 81.305, and 

background concentrations are low notwithstanding the fact that, historically, minor 

agricultural sources have not been subject to NSR permitting or related controls. For 

instance, preliminary data published by CARB indicates that the highest PM10

concentration measured in Ventura County in 2012 and 2013 (at the El Rio monitoring 

site) was less than 60 micrograms per cubic meter (μg/m3), i.e., 60% less than the 

applicable NAAQS for PM10 of 150 μg/m3. Thus, we find that the continuation of the de 

facto status quo with respect to certain minor agricultural sources being exempt from 

NSR would not interfere with continued attainment of the applicable NAAQS. 

Fourth, in response to EPA’s classification of Ventura County as “serious” nonattainment 

for the 1997 8-hour ozone NAAQS, in June 2008, CARB submitted an attainment 

demonstration plan to EPA titled Final Ventura County 2007 Air Quality Management 

Plan, May 13, 2008 (“2007 Ventura County Ozone Plan”), that includes a control 

strategy to attain the 1997 8-hour ozone standard by June 2013. The control strategy in 

the 2007 Ventura County Ozone Plan relies primarily on mobile source controls and does 

not rely on NSR controls for minor agricultural sources. While EPA has not taken action 

on the 2007 Ventura County Ozone Plan, EPA has determined, based on ambient ozone 

concentration data for 2009-2011, that Ventura County has attained the 1997 8-hour 

ozone standard. See 77 FR 71551 (December 3, 2012). Moreover, CARB data predicts a 

continuing downward trend for both VOC and NOx emissions in Ventura County through 

2025 under the current regulatory program for stationary, mobile, and area sources that 

does not include NSR for minor agricultural sources. See CARB Almanac Emission 

Projection Data (published in 2013) for Ventura County for years 2012 and 2025. 

Lastly, EPA has classified Ventura County as “serious” nonattainment for the 2008 ozone 

standard. See 40 CFR 81.305. Attainment demonstration plans for the 2008 ozone 

standard are not due yet, but such plan, consistent with past ozone plans for Ventura 

County, will need to account for the permit exemptions in Rule 23 in developing the 

control strategy or take the necessary steps under state law (CH&SC 42301.16(c)) to 

remove the exemption if the VCAPCD decides to do so. 
13 

Therefore, for the reasons discussed above, EPA concludes that the new exemption in 

Rule 23 for certain new or modified minor agricultural sources contained in section J.16 

would not interfere with attainment and RFP or any other applicable requirement of the 

CAA and is therefore approvable under CAA Section 110(l). 

Rule Deficiencies 

No deficiencies were found that would prevent EPA from recommending full approval of 

VCAPCD Rule 23 into the SIP. 

EPA Action 

EPA has reviewed the submitted rule in accordance with the Rule Evaluation criteria described 

earlier in this document. Consistent with the requirements of 40 CFR Subpart I, all major 

stationary sources are required to obtain an ATC permit prior to construction. For minor sources, 

EPA believes that the emissions from the types and sizes of equipment and operations exempted 

from NSR permit requirements are consistent with the flexibility afforded to states to regulate 

only those sources as necessary to assure attainment and maintenance of the NAAQS (40 CFR 

51.160(e)). 

Consistent with the requirements of CAA Section 110(l), we conclude that the new and revised 

exemptions would not interfere with reasonable further progress and attainment of any of the 

NAAQS in Ventura County or any other applicable requirement of the CAA and thus is 

approvable under Section 110(l) of the CAA because of (1) the limited nature of the exemption, 

(2) the presence of other regulatory controls for exempt agricultural sources, (3) the low 

background concentrations for the NAAQS pollutants in Ventura County other than ozone, and 

(4) the fact that the submitted ozone plan for the county does not rely on NSR controls for minor 

agricultural sources and that the downward trend in ozone precursor emissions in Ventura 

County is predicted to continue well into the future. 

EPA recommends full approval of the following VCAPCD rule for incorporation into the 

California Applicable SIP, pursuant to Section 110(k)(3) of the CAA as amended in 1990: 

• Rule 23 – Exemptions from Permit (amended on November 12, 2013, submitted on May 

13, 2014), replacing Rule 23, Exemptions from Permit, as approved in to the SIP on 

December 7, 2000 (65 FR 76567). 

EPA Recommendations 

The following revisions to Rule 23 are not currently a basis for rule disapproval, but are 

recommended as improvements when this rule is amended. 

• F.10.a – The term “Clean Air Solvents” should be defined in the SIP for VCAPCD, either 

in Rule 23 or in Rule 2, Definitions. 

• J.16 – A threshold for PM2.5 should be added to the table of federal major source 

thresholds listed in this provision. 
14 

Attachments 

1. VCAPCD Rule 23, Exemptions from Permit, as submitted on May 13, 2014. 

2. VCAPCD Staff Report (Rule 23) dated September 23, 2013. 

3. VCAPCD Staff Report (Rule 23) dated February 25, 2011. 

4. VCAPCD Staff Report (Rule 23) dated February 29, 2008. 

5. VCAPCD Staff Report (Rule 23) dated September 12, 2006. 

6. CARB Staff Report: Initial Statement of Reasons for Rulemaking, Public Hearing to 

Consider the Large Confined Animal Facility Definition, May 6, 2005. (Cover only and 

page 33) 

7. VCAPCD Staff Report (Rule 23) dated October 12, 2004. 

8. VCAPCD Board Letter (Rule 23) dated April 13, 2004.

9. California Senate Bill 700, dated September 22, 2003. 

10. VCAPCD SIP Approved Rule 23, approved December 7, 2000. 

11. U.S. EPA, “EPA White Paper for Streamlined Development of Part 70 Permit 

Applications” dated July 10, 1995. 

12. CARB, “Select 8 Summary,” summarizes 2012 and 2013 PM2.5 and PM10 ambient 

monitoring data from Ventura County monitoring sites. 

13. CARB, “Almanac Emission Projection Data, 2012 Estimated Annual Average Emissions, 

Ventura County APCD.” 

14. CARB, “Almanac Emission Projection Data, 2025 Forecasted Annual Average 

Emissions, Ventura County APCD.”