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

San Joaquin Valley Air Pollution Control District’s

Rule 4625, Wastewater Separators

October 2010

Prepared by Joanne Wells

Approved by Andrew Steckel
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San Joaquin Valley Unified Air Pollution Control District (SJVUAPCD)

Submitted Rule

 Rule 4625, Wastewater Separators was originally adopted on April 11, 1991 as Rule 

463.4, amended on December 17, 1992, and submitted on August 24, 2007. The 

submittal was determined complete on September 17, 2007. There are no other 

submittals of this rule on which EPA has not acted.

Applicable SIP Rules

 The SIP version of this rule is SJVUAPCD Rule 463.4, Wastewater Separators, adopted 

on April 11, 1991, approved on May 13, 1993 (58 FR 28354).

Background

On January 2, 2008 (73 FR 48), EPA published a direct final approval of revisions to the 

California State Implementation Plan (SIP). These revisions concerned SJVUAPCD rules that 

address reduction of animal matter, and volatile organic compound (VOC) emissions from crude 

oil operations and petroleum refinery equipment, asphalt paving and maintenance, and petroleum 

solvent dry cleaning. The direct final action was published without prior proposal because EPA 

anticipated no adverse comment. The direct final rule stated that if adverse comments were

received by February 1, 2008, EPA would publish a timely removal in the Federal Register. 

EPA received timely adverse comments. Consequently, we removed the direct final approval of 

SJVUAPCD Rules 4104, 4402, 4404, 4453, 4454, 4625, 4641, and 4672 (see 73 FR 13440). 

This technical support document (TSD) only addresses SJVUAPCD Rule 4625. We do not 

intend to take final action based on our January 2008 proposal regarding this rule. As a result, we 

are not summarizing or replying to comments submitted in response to our January 2008 

proposal regarding this rule. No specific comments were received for Rule 4625. However, the 

general comments received expressed concern regarding whether these rules complied with the 

requirements for reasonably available control technology (RACT) described in CAA Section 

182(b)(2) and elsewhere. 

Purposes of Rule and Rule Amendments

Section 110(a) of the CAA requires states to submit regulations that control VOCs, oxides of 

nitrogen, particulate matter, and other air pollutants which harm human health and the 

environment. This rule was developed as part of the local agency’s program to control VOC 

emissions.

The purpose of Rule 4625 is to limit VOC emissions from oil-water wastewater separators by 

requiring covers and use of vapor loss control devices with a control efficiency of at least 90%. 

The amendments to approved SIP Rule 463.4 are summarized as follows: 

 The rule is renumbered from 463.4 to 4625.

 The format is improved, the rule purpose is added, the definition of VOC is deleted. 

 Paragraph 4.3 is added, which allows an exemption from the BACT and offset 

requirements of Rule 2201 for existing facilities where an incineration device has been 

added for the sole purpose of complying with the requirements of this rule. 
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Rule Evaluation 

EPA is primarily using the following three criteria to evaluate Rule 4625.

1. Enforceability – CAA §110(a)(2)(A) requires that regulations submitted to EPA 

for SIP approval must be clear and legally enforceable. 

2. Anti-Backsliding - CAA §110(l) restricts certain SIP revisions that would relax 

existing SIP-approved requirements. 

3. Rule Stringency – CAA §172(b) and 182(a)(2)(A) require ozone nonattainment 

areas to implement RACT for ozone precursors. The SJVUAPCD regulates an 

extreme 1-hr ozone nonattainment area and an extreme 8-hr ozone nonattainment 

area (see 40 CFR part 81) and must fulfill the requirements of RACT.

On April 16, 2009, SJVUAPCD adopted its “RACT Demonstration for Ozone SIP,” which 

provides the District’s demonstration that RACT is implemented for all appropriate rules. This 

includes several pages discussing Rule 4625. (See Cover and applicable pages attached.) In 

summary, SJVUAPCD states that: 

 Rule 4625 VOC control requirements are basically the same as contained in EPA’s 

relevant control technique guidelines (CTG). The applicable CTG for these sources 

is “Control of Refinery Vacuum Producing Systems, Wastewater Separators and 

Process Units”, EPA-450/2-77-025, October 1977.

 Overall, Rule 4625 is as stringent as the federal New Source Performance Standard 

(NSPS), Standards of Performance for VOC Emissions from Petroleum Refinery

Wastewater Systems, 40 CFR 60 Subpart QQQ, November 23, 1988 (53 FR 47623). 

 The District believes that Rule 4625 is as stringent as the NESHAP/MACT standard, 

National Emission Standards for Oil-Water Separators and Organic-Water Separators, 

40 CFR 63 Subpart VV, July 1, 1996 (61 FR 34195).

 Rule 4625 imposes very similar requirements to those in other large California 

nonattainment areas, such as South Coast (SCAQMD) and Bay Area (BAAQMD). 

In general, we concur with the District’s analysis that this rule imposes requirements that are 

similar to the requirements in the 1977 CTG. However, Rule 4625 includes an exemption (4.2) 

for Air Flotation Units which is not found in the CTG or in other California districts’ rules. 

Rule 4625 has requirements for controlling VOCs that are similar to the basic requirements 

stated in the NSPS and the NESHAP/MACT. However, these regulations have requirements for 

stricter VOC controls (95%) and additional design requirements for controlling fugitive 

emissions or breathing losses, and additional requirements for inspections and maintenance. 

These stricter requirements minimize fugitive emissions and vapor losses from properly designed 

and well maintained oil-water separators and their associated slop or skimmed oil storage tanks. 

Rule 4625 general requirements are similar to the requirements found in other large California 

nonattaiment areas such as Ventura, South Coast and Bay Area. However, both SCAQMD Rule 
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1176 (1996) and BAAQMD Reg. 8, Rule 8 (1993) require vapor control devices with 95% 

efficiency whereas Rule 4625 only requires 90% efficiency. The SCAQMD and BAAQMD rules 

also include more specific design, operation, inspection and maintenance requirements that are 

similar to the requirements found in the NSPS (Subpart QQQ) and NESHAP (Subpart VV). 

SJVUAPCD Rule 4625 requirements are the original Rule 463.4 requirements, adopted in 

1991.This rule has not been updated to include more current requirements for design, 

maintenance, inspections and operation as specified in the NSPS and NESHAP/MACT or to 

replace outdated test methods.

In summary, the changes to Rule 4625 are mostly administrative and do not change or relax the 

requirements of this rule. The rule is generally enforceable, but needs to be revised to replace 

outdated and inappropriate test methods. In addition, the new exemption (4.3) is not appropriate 

and SJVAPCD has not adequately demonstrated that this rule satisfies current RACT. These 

deficiencies are discussed in more detail in the Rule Deficiencies section below. 

Rule Deficiencies

The following deficiencies preclude full approval of Rule 4625 into the SIP:

1. The December 1992 amendment added exemption 4.3, which reads “For existing facilities, if 

an incineration device is added or modified for the sole purpose of complying with the 

requirements of this rule, such a device shall be exempt from the Best Available Control 

Technology and the Offset requirements of Rule 2201 (New and Modified Stationary Source 

Review Rule)”. This exemption should be removed from Rule 4625. Any exemptions to 

NSR requirements should be evaluated in context of SJVUAPCD’s NSR program (e.g., Rule 

2020) and incorporated within the NSR program only if appropriate. Such exemptions 

should not be in source-specific prohibitory rules like Rule 4625. 

2. Although Rule 4625 includes similar requirements to the 1977 CTG, SJVUAPCD has not 

adequately demonstrated that Rule 4625 currently implements RACT because RACT can 

change over time as control technology improves and/or becomes more available. More 

stringent requirements exist in the NSPS (1988), NESHAP (1995), BAAQMD Rule 8-8 

(1993) and SCAQMD 1176 (1996). These regulations have requirements for stricter VOC 

controls (see, e.g., 95% requirement in SCAQMD Rule 1176, section (e)(2)(A)(ii) and 

(e)(6)), additional design requirements for controlling fugitive emissions or breathing losses 

(see, e.g., BAAQMD Regulation 8 Rule 8, section 302.4), and additional requirements for 

inspections and maintenance (see, e.g., BAAQMD Regulation 8 Rule 8, section 302.4 and 

302.6). 

3. The exemption for air flotation units precludes regulation of potentially significant VOC 

sources (section 4.2). Even though these sources are currently regulated via District permit 

conditions, SJVUAPCD should subject them to SIP requirements as part of Rule 4625 or 

demonstrate why that is not necessary. There is no specific allowance in the CTG or other 

guidance documents for exempting air flotation units from regulation and no other California 

air district rules include such an exemption under their similar rules.

4. To improve enforceability, SJVUAPCD should revise section 6.0 Test Methods to remove 
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inappropriate or outdated test methods such as 6.1.2 ARB Method 432 for paints and 

coatings, and 6.1.3 which refers to an obsolete document superseded by EPA Method 204 for 

determining capture efficiency (40 CFR 51). We recommend including EPA Test Method 21 

(measurements of leaks) as referenced in SJVUAPCD Rule 4455, Section 6.4 Test Methods, 

or SCAQMD Rule 1176, Section (h). 

5. The RACT Demonstration mentions that the requirements in SJVUAPCD Rule 4455, 

“Components at Petroleum Refineries, Gas Liquids Processing Facilities and Chemical 

Plants” apply to oil-water separators. SJVUAPCD should include those requirements 

directly in Rule 4625 or by reference to improve enforceability, or demonstrate that this is 

not appropriate.

6. To ensure ongoing compliance and strengthen enforceability, SJVUACPD should add to the 

rule requirements for inspections of covers, access hatches and other openings and emissions 

control equipment, along with recordkeeping requirements for inspections and testing or 

demonstrate that this is not appropriate. For example, please see SCAQMD Rule 1176, 

section (f) and (g). 

7. SJVUAPCD should delete or justify exemption 4.1 for wastewater separators exceeding a set 

value for a sump surface area to the rate of oil vapor loss ratio. The only other rule where we 

found such exemption is SCAQMD Rule 464 for Wastewater Separators, last amended 

December 7, 1990. This exemption is not found in the newer SCAQMD Rule 1176, “VOC 

Emissions from Wastewater Systems” amended September 13, 1996, which also addresses 

wastewater separators and which largely supersedes Rule 464. 

EPA Action

The revisions reflected in submitted Rule 4625 are largely administrative changes that do not 

substantively weaken the SIP, but the deficiencies discussed above preclude full approval. As a 

result, EPA staff recommends a simultaneous limited approval and limited disapproval of the 

August 24, 2007 submittal of SJVUAPCD Rule 4625 pursuant to section 110(k) of the CAA as 

amended in 1990. If finalized as proposed, the rule deficiencies identified above would trigger 

CAA Section 110(m) sanction and Section 110(c) federal implementation plan (FIP) obligations

because the San Joaquin Valley is an extreme nonattainment area for ozone required to 

implement RACT. 

EPA Recommendations

The following revisions are not currently the basis for rule disapproval, but are recommended as 

improvements when this rule is amended.

 We suggest deleting section 7.0 Compliance Schedule since it is no longer applicable. 

Guidance and Policy Documents

Guidance and policy documents that we used to help evaluate rules and RACT requirements 

consistently include the following:

1. Portions of the proposed post-1987 ozone and carbon monoxide policy that concern 

RACT, 52 FR 45044 (November 24, 1987).
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2. Requirements for Preparation, Adoption, and Submittal of Implementation Plans, U.S. 

EPA, 40 CFR part 51.

3. Addendum to the General Preamble for the Implementation of Title I of the Clean Air 

Act Amendments of 1990, 59 FR 41998 (August 16, 1994).

4. “Issues Relating to VOC Regulation Cutpoints, Deficiencies, and Deviations”, EPA (May

25, 1988). [The Bluebook]

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

Region 9 (August 21, 2001). [The Little Bluebook]

6. “Control of Refinery Vacuum Producing Systems, Water Separators and Process Units”, 

EPA-450/2-77-025, October 1977.

7. “Standards of Performance for VOC Emissions from Petroleum Refinery Wastewater 

Systems”, 40 CFR 60 Subpart QQQ, November 23, 1988 (53 FR 47623).

8. “National Emission Standards for Oil-Water Separators and Organic-Water Separators”, 

40 CFR 63 Subpart VV, July 1, 1996 (61 FR 34195).

Attachments

1. SJVUAPCD Rule 4625, “Wastewater Separators” as submitted on August 24, 2007.

2. SJVUAPCD Rule 463.4, “Wastewater Separators” adopted on April 11, 1991, SIP 

approved on May 13, 1993.

3. “2009 RACT SIP”, SJVUAPCD (April 16, 2009). [Cover plus sections relevant to 

SJVUAPCD Rule 4625].