UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

REGION IX AIR DIVISION

Technical Support Document 

for

EPA’s Direct Final Rulemaking

for the

California State Implementation Plan

YOLO-SOLANO AIR QUALITY MANAGEMENT DISTRICT

Rule 2.31, Solvent Cleaning and Degreasing

Prepared by: Arnold Lazarus

Reviewed by: Andy Steckel

August 2014
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RULE IDENTIFICATION 

Agency: Yolo-Solano Air Quality Management District 

(YSAQMD)

SIP Approved Rules: Rule 2.31 - Surface Preparation and Cleanup

Adopted - April 27, 1994

Submitted - November 30, 1994

EPA Approved - April 02, 1999 (64 FR 15922)

Rule 2.13 - Organic Solvents

Adopted - May 24, 1994

EPA Approved - April 30, 1996 (61 FR 18962)

Rule 2.15 - Disposal and Evaporation of Solvents

Submitted - June 22, 1978

EPA Approved - January 29, 1979 (44 FR 5663)

Rule 2.24 - Solvent Cleaning Operations (Degreasing)

Adopted - November 14, 1990

Submitted - May13, 1991

EPA Approved - December 13, 1994 (59 FR 64130)

Subject of this TSD: Rule 2.31 - Solvent Cleaning and Degreasing

Amended - May 8, 2013

Submitted - February 10, 2014

RULE SUMMARY - YSAQMD Rule 2.31, Solvent Cleaning and Degreasing, is a rule 

designed to reduce volatile organic compound (VOC) emission from operations 

associated with solvent cleaning and degreasing.

YSAQMD Rule 2.13, Organic Solvents, is designed to reduce VOC emission from 

operations associated with the use of organic solvents. 

YSAQMD Rule 2.15, Disposal and Evaporation of Solvents, is designed to regulate 

disposal and evaporation of photochemically reactive organic solvents or compounds 

into the atmosphere

YSAQMD Rule 2.24, Solvent Cleaning Operations (Degreasing), limits VOC emission 

from operations associated with solvent degreasing.

Rule 2.31 has been revised from the adopted version in scope and stringency. The rule 
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has been expanded to incorporate the concepts of Rules 2.13, “Organic Solvents,” 2.15, 

“Disposal and Evaporation of Solvents,” and 2.24, ”Solvent Cleaning Operations 

(Degreasing).” Concurrently, Rules 2.13, 2.15 and 2.24 are being rescinded in the SIP. 

A new category, Aerospace Solvent Cleaning has been added to Rule 2.31. The May 8, 

2013 SIP submitted version of Rule 2.31 is more stringent than the currently SIP 

approved rules, 2.13, 2.15, 2.24 and 2.31. The revised Rule 2.31 establishes VOC 

limits and workplace requirements for cleaning and degreasing products sold, 

distributed or used within the District. It also prescribes administrative requirements for 

recordkeeping and test methods. Major changes from the approved SIP rule include:

1. Section 101, Purpose, was revised to include degreasing operations.

2. Section 102, Applicability, was revised to include anyone who sells or

distributes VOC containing materials for solvent cleaning or degreasing.

3. Sections 110 through Sections 114, Exemptions, were expanded and 

reorganized as follows:

a. Section 110, General, classifies certain operations that are exempt from 

the provisions of Rule 2.31, and reduces the size of an exempt degreaser

from five gallons to one gallon which serves to strengthen the rule.

b. Section 111, Solvent Requirements, is a revision which requires a 

YSAQMD permit or written exemption from the air pollution control officer 

(APCO) in order to be exempted from the requirements of Section 301. 

Previously, a person could just claim an exemption for specialized usage 

which pertained to wipe cleaning. An exemption for solvents used for the 

cleaning of sterilization ink indicating equipment limiting usage to less than

1.5 gallons per day was also added to the rule. Permitting is also now 

required of these sources, which strengthens the rule by further restricting 

rule exemptions.

c. Section 112, General Prohibition, was revised to describe a limited 

exemption from Section 301.4 for use of closed cleaning or non-propellant 

spray bottles which contain less than 16 fluid ounces.

d. Section 113, Limited Aerosol, was revised to exempt cleaning with aerosol 

products if they comply with size, daily usage, YSAQMD permit or written 

exemption from the APCO and the products comply with California Air 

Resources Board (CARB) regulations limiting VOC content of aerosol 

coatings.

e. Section 114, Aerospace Vehicle or Components, specifies exemptions to

the aerospace requirements which are newly incorporated into Rule 2.31, 

Section 301.1, VOC Content Limits. The requirements for aerospace in 

this rule as a whole establish more stringent requirements than previously 

existed in the EPA-approved YSAQMD SIP. 

4. Section 200, Definitions, was revised and expanded to include degreasing, 

aerospace and other terms to help clarify Rule 2.31 requirements. 

 
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5. Section 300, Standards, has been reorganized as follows:

a. Section 301, Solvent Cleaning Operations, applies to solvent cleaning

operations and specifies the VOC content limits for all categories related 

to solvent cleaning including a new category that has been created 

specifically for cleaning related to aerospace vehicle or components. 

The other parts of Section 301 involve cleaning techniques, application 

equipment cleanup and general prohibition. The VOC limits are more 

stringent in all categories compared to the SIP approved rule and, except 

for Lithographic, Letterpress and Ultraviolet (except screen printing),

match the limits in South Coast 1171. The printing solvent limits have 

been lowered from 900 g/l and 800 g/l for Lithographic, Letterpress 

operations and Ultraviolet (except screen printing) to 238 g/l. 

Aerospace solvent cleaning is limited to 200 g/l or 45 mmHg and identical 

to South Coast Rule 1124 – Aerospace Assemble and Component 

Manufacturing Operations.

b. Section 302, Solvent Degreasing Operations, establishes operational 

requirements for solvent degreasers.

 c. Section 303, Cold Cleaner Requirements, establishes operational 

requirements for the use of “cold cleaners” which include but are not 

limited to temperature, solvent drainage, placement, cover specifications 

and methodology.

d. Section 304, Open Top Vapor Degreaser Requirements, establishes 

operational requirements for the use of Open Top Vapor Degreasers 

(OTVG) which specify design requirements, usage, temperature, 

technique, placement, cover specifications, safety procedures and solvent 

recovery. OTVG requirements were not part of SIP approved Rule 2.31.

e. Section 305, Airless/Airtight Cleaning System Requirements, establishes 

requirements for the operation, solvents practice and gauge necessity for 

an airless/airtight cleaning system (AACS). This provision is new to Rule 

2.31. Cleaning occurs in a closed system so no VOCs should be released 

during, before or after a cleaning operation. The specifications for the 

AACS are found in Section 200 Definitions and are identical to the 

approved SIP for San Joaquin Valley Unified APCD Rule 4462. 

f. Section 306, Remote Reservoir Cold Cleaner Requirements, establishes 

requirements for the use of a Cold Cleaner equipped with a Remote 

Reservoir.

g. Section 307, Storage and Disposal, makes small revisions to clarify the 

requirements for storage and disposal of solvents. It lowers the disposal 

limits of all materials containing VOCs to zero evaporation into the 

atmosphere with the exception of filling or emptying into normally closed 

leak-proof containers. Previously, there was a limit of 1 1⁄2 gallons per day

in Rule 2.15, so this strengthens the SIP.

h. Section 308, Emission Control System (ECS), allows the use of an 

alternative to the methods and systems of Sections 301 through Sections 

307 providing it meets the performance standards of a capture efficiency 

of ≥ 90% of the emissions generated by the surface preparation and 
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cleanup and one of the following.

1. The control device has a control efficiency of ≥ 95% by weight, or

2. The VOC Emission System has an output of < 50 parts per million 

by weight calculated as carbon with no dilution.

i. Conveyorized Degreasers, a category previously regulated by Rule 2.24, 

is not addressed in Rule 2.31. YSAQMD has clarified that “there are 

currently no conveyorized degreasers and there are no sources planning 

to construct one in the District.”1

6. Section 400, Administrative Requirements, has been added to Rule 2.31. It 

prohibits anyone from specifying any solvents use and cleanup that would result 

in a violation of Rule 2.31; specifies informational directives to sellers and 

distributors of solvents containing VOC content; and describes an Operation and 

Maintenance Plan with permit requirements to any person using an Emission 

Control System pursuant to Section 308 of Rule 2.31.

7. Section 500, Monitoring and Records, has been revised and reorganized as 

follows:

a. Sections 501 Record Keeping – General addresses general record 

keeping and record maintenance.

b. Section 502 Emission Control System (ECS), formerly “Test Methods,” 

addresses the recordkeeping of ECS (Section 308).

c. Section 503 Burden of Proof, a new addition to the Rule, specifies the

records needed for exemptions as verification to an APCO.

d. Section 504 Record Retention specifies how long a person must keep 

records and make them available to the APCO.

8. Section 600, Test Methods and Calculations, is a new section, replacing the SIP 

version which was Section 502, Test Methods. This section updates test 

methods for VOC content and includes calculations of VOC Content and VOC 

composite partial pressure and determination of “capture efficiency” and “control 

efficiency.” The determination of VOC from Spray Gun Cleaning Systems is also 

described in Section 600.

EPA EVALUATION CRITERIA – The following criteria were used to evaluate the 

submitted rule.

1. Enforceability - The Bluebook (Issues Relating to VOC Regulation Cutpoints, 

Deficiencies, and Deviations, EPA, May 25, 1988) and the Little Bluebook 

(Guidance Document for Correcting Common VOC & Other Rule Deficiencies,

EPA Region 9, August 21, 2001) were used to help evaluate compliance with the 

CAA §110(a)(2)(A) requirement for enforceability. 

 

1 Communication from M. Ehrhardt, P.E., Executive Director, YSAQMD, to A. Steckel, Chief, Rulemaking 

Office, EPA Region 9, October 23, 2014.
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2. Stringency - Rule 2.31 was partially evaluated against EPA’s Control Technique 

Guidelines (CTGs) titled, “Control of Volatile Organic Emissions from Solvent 

Metal Cleaning” (EPA-450/2-77-022, November 1977) and “Control Technique 

Guidelines for Industrial Cleaning Solvents” (EPA-453/R-06-001, September 

2006), “Control Technique Guidelines for Flexible Package Printing” (EPA 

453/R-06-003,September 2006), “Control of Volatile Organic Compound 

Emissions from Coating Operations at Aerospace manufacturing and Rework 

Operations” (EPA-453/R-97-004, December 1997), CARB’s RACT/BARCT 

guidance titled, “Organic Solvent Cleaning and Degreasing Operations” (July 18, 

1991), and other state and local rules for this category were used to help 

evaluate the RACT requirements of CAA §182(b)(2). The solvent limits and 

requirements were also compared to South Coast Air Quality Management 

District’s (SCAQMD) Rules 1122 “Solvent Degreasers,” SCAQMD Rule 1124

“Aerospace and Assembly Operations and Component Coating Operations,” and

SCAQMD Rule 1171 “Solvent Cleaning Operations”. 

3. SIP Relaxation - We have evaluated this SIP revision to determine whether it 

would interfere with any applicable requirement concerning attainment and 

reasonable further progress (RFP) or any other applicable requirement of the Act 

(CAA §110(l)) or modify, in a nonattainment area, any SIP-approved control 

requirement in effect before November 15, 1990 (CAA §193).

The VOC limits, recordkeeping requirements and other provisions of Rule 2.31 are clear 

and adequately fulfil the enforceability requirements summarized in paragraph #1 

above. Rule 2.31 implements RACT because it is generally as stringent as the 

guidelines listed in paragraph #2 above. The submitted rule is significantly more 

stringent than the version of Rules 2.13, 2.15, 2.24 and 2.31 previously approved into 

the SIP, so the submitted rule does not relax the SIP and complies with CAA §110(l) 

and §193 consistent with paragraph #3 above.

RULE DEFICIENCIES – We have identified no deficiencies with Rule 2.31 sufficient for 

EPA to propose less than full approval.

EPA ACTION

The submitted rule revisions to Rule 2.31 strengthen the SIP. The rule satisfies relevant 

CAA §110 and part D requirements. According to the YSAQMD staff report, there will 

be no impact in emission reduction. EPA staff recommends full approval of Rule 2.31 

pursuant to CAA §110(k) and removal from the SIP of Rules 2.13, 2.15 and 2.24.

EPA RECOMMENDATIONS

The following revision is not currently the basis for rule disapproval but is recommended 

for the next time the rule is amended.
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1. Lower the VOC content limit for Ultraviolet (UV) (except screen printing) in 

Section 301.1 VOC Content Limits, Table 1 to 100 grams/liter, consistent with 

South Coast AQMD Rule 1171.

REFERENCES

1. YSAQMD Rule 2.31, “Surface Preparation and Cleanup,” EPA Approved -

December 13, 1994 (59 FR 64130).

2. YSAQMD Rule 2.31, “Solvent Cleaning and Degreasing,” Submitted February 

10, 2014.

3. YSAQMD Rule 2.13, “Organic Solvents,” EPA Approved - April 30, 1996 (61 FR 

18962).

4. YSAQMD Rule 2.15, “Disposal and Evaporation of Solvents,” EPA Approved -

January 29, 1979 (44 FR 5663).

5. YSAQMD Rule 2.24, “Solvent Cleaning Operations (Degreasing),” EPA 

Approved - December 13, 1994 (59 FR 64130).

6. “Control of Volatile Organic Emissions from Solvent Metal Cleaning” EPA-450/2-

77-022, November 1977.

7. “Control Technique Guidelines for Industrial Cleaning Solvents” EPA-453/R-06-

001, September 2006.

8. “Control Technique Guidelines for Flexible Package Printing” EPA 453/R-06-003,

September 2006.

9. “Control of Volatile Organic Compound Emissions from Coating Operations at 

Aerospace manufacturing and Rework Operations” EPA-453/R-97-004,

December 1997.

10. CARB’s RACT/BARCT guidance titled, “Organic Solvent Cleaning and 

Degreasing Operations” (July 18, 1991).

11. SCAQMD) Rule 1122, “Solvent Degreasers,” EPA Approved - February 8, 2006 

(71 FR 6350).

12. SCAQMD) Rule 1124, “Aerospace and Assembly Operations and Component 

Coating Operations,” EPA Approved - August 13, 2002 (67 FR 52611).

13. SCAQMD) Rule 1171, “Solvent Cleaning Operations,” EPA Approved –

September 29, 2011 (76 FR 60376).

14. “Issues Relating to VOC Regulation Cutpoints, Deficiencies, and Deviations,”

(a.k.a., Bluebook) EPA OAQPS, May 25, 1988 (web citation).

15. “Guidance Document for Correcting Common VOC & Other Rule Deficiencies,” 

(a.k.a., Little Bluebook), EPA Region 9, August 21, 2001 

(http://www.epa.gov/region09/air/sips/littlebluebook2001.pdf).
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