





                                       
                 UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
                     REGION IX AIR AND RADIATION DIVISION








                                       
                                       
                          Technical Support Document 
                                      for
                              EPA's Rulemaking
                                   for the 
                     California State Implementation Plan
                                       
            Mojave Desert Air Quality Management District Rule 401 
                               Visible Emissions









                              
                              Christine Vineyard
                                       
                                 December 2022
                                       
                                       
                                       
                                       
                                       
                                       





RULE IDENTIFICATION - 
Agency
Mojave Desert Air Quality Management District (MDAQMD)

SIP Approved Rule
San Bernardino County portion of MDAQMD
Rule 401  -  Visible Emissions 
Adopted  -  May 07, 1976
Submitted  -  June 6, 1977
EPA Approved  -  September 8, 1978 (43 FR 40011)

Riverside County (Blythe/Palo Verde Valley) portion of the MDAQMD
Rule 401  -  Visible Emissions
Adopted  -  March 2, 1984
Submitted  -  July 10, 1984
EPA Approved  -  January 29, 1985 (50 FR 3906)

Subject of this TSD
Rule 401  -  Visible Emissions
Amended  -  August 26, 2019 
Submitted  -  January 08, 2021

Completeness Finding
Complete by operation of law: July 08, 2021


BACKGROUND - Mojave Desert Air Quality Management District (MDAQMD or "District") Rule 401, Visible Emissions, was originally adopted on May 7, 1976. On February 1, 1977, California Air Resources Board Executive Order G-73 adopted a rulebook, which included Rule 401, for non-South Coast Air Basin (SCAB) areas of Los Angeles, Riverside and San Bernardino Counties. On July 25, 1977, the San Bernardino County Air Pollution Control District (SBCAPCD) adopted Rule 401 into its rulebook. In 1993, the SBCAPCD became the MDAQMD. Rule 401 currently addresses a single visible emission limitation. This is inconsistent with the current provisions contained in the California Health and Safety Code ("H&S Code") and current District practices. The MDAQMD proposes to amend Rule 401 to conform to the requirements in H&S Code §§41701.5, 41701.6, and 41704. General opacity regulations as readopted in 1977 have not been modified, as they are more stringent than the H&S Code. To conform with the California H&S Code, the MDAQMD is adding equipment specific emissions limits exemptions, definitions, and test methods. All applicable provisions in the California H&S Code are currently enforced by the MDAQMD; therefore, no changes in emissions or controls are anticipated.

The Environmental Protection Agency (EPA) designated the San Bernardino County portion of the MDAQMD nonattainment for the federal particulate matter with an aerodynamic diameter less than or equal to a nominal 10 micrometers (PM10) standard in two separate actions, the first in 1990 (for the Searles Valley), the second in 1994 (for the remainder of the MDAQMD in San Bernardino County). The EPA designated MDAQMD unclassifiable/attainment for the federal particulate matter with an aerodynamic diameter less than or equal to a nominal 2.5 micrometers (PM2.5) standards.

RULE SUMMARY  -  Rule 401 provides limits for visible emissions from all sources of air pollution emissions in the district. Rule 401 was amended to be consistent with the applicable California H&S Code provisions already enforced.  

Changes from the approved state implementation plan (SIP) rule include:
1.	Section (A) was added to outline the purpose, applicability, and severability of Rule 401.

2.	Section (B) was added to comprise definitions such as "opacity," "visible emissions," "observer," etc. for clarity of the rule.

3.	Section (C) was added to outline the general visible emission limitations. Although California H&S Code §41701 allows up to No. 2 on the Ringelmann Chart (40% opacity), Rule 401 limits emissions opacity to No. 1 on the Ringelmann Chart (20% opacity), as adopted in previous iterations of this rule and as approved into the SIP. 

3.  	Section (C) outlines equipment-specific visible emissions limitations for abrasive blasting, drinking water systems, gas turbines, and diesel pile-driving hammers, as they relate to equipment subject to 40 CFR Part 60, 40 CFR Part 61, or 40 CFR Part 63.

5.	Section (D) outlines specific exemptions for:
 Open burning that is in compliance with District Rule 444.
 Distributing agricultural aids via aircraft.
 Agricultural operations necessary for the growing of crops or raising of fowl or animals.
 The use of visible emissions generating equipment in training sessions conducted by governmental agencies necessary for certifying persons to evaluate visible emissions for compliance with applicable District rules and regulations.
 Emissions from vessels using steam boilers during emergency boiler shutdowns for safety reasons.
 Fugitive dust emissions from rock crushing facilities in existence prior to January 1, 1970, at a location where the population density is less than 10 persons per square mile within a seven-mile radius of the facilities.
 Emissions during a breakdown condition, as long as the discharge is reported in accordance with District requirements.
 Emissions from teepee burners during the disposal of forestry and agricultural residues or forestry and agricultural residues with supplementary fossil fuels when the emissions result from the startup or shutdown of the combustion process or from the malfunction of emission control equipment. This exemption does not apply to emissions exceeding a period of time aggregating more than 30 minutes in any 24-hour period, nor to emissions resulting from the failure to operate and maintain control equipment in good working order.
 Burners used to produce energy and fired by forestry and agricultural residues with supplementary fossil fuels when the emissions result from the startup or shutdown of the combustion process or from the malfunction of emission control equipment.
 Methanol fuel manufacturing plants that manufacture not more than 2,000,000 gallons of methanol fuel per day from wood, agricultural waste, natural gas, or coke (exclusive of petroleum coke). This exemption shall be available to only one manufacturing plant in the District and is effective only when the District is designated as an "attainment area" pursuant to the federal CAA. This exemption shall remain in effect until 5 years after construction of the plant and have no force and effect with respect to the plant on and after that date.
 The use of an obscurant for the purposes of training military personnel and the testing of military equipment by the United States Department of Defense on any military reservation.
 Fugitive dust emissions generated for the purposes of training military personnel and the testing of military equipment by the United States Department of Defense on any military reservation, within the boundaries of said military reservation.
 The use of an orchard, field crop, or citrus grove heater that does not produce unconsumed solid carbonaceous material at a rate greater than that allowed by State law, which is 1 gram per minute of unconsumed solid carbonaceous material.
 6. 	Section (E) outlines federal test methods for compliance verification:
 EPA Method 9  -  Visual Determination of the Opacity of Emissions from Stationary Sources.
 EPA Method 22  -  Visual Determination of Fugitive Emissions from Material Sources and Smoke Emissions from Flares.

EVALUATION CRITERIA  -  The following criteria were used to evaluate the submitted rule:
 Enforceability  -  CAA section 110(a)(2)(A) requires SIPs to "include enforceable emissions limitations and other control measures, means, or techniques . . . as may be necessary or appropriate to meet the applicable requirements of [the CAA]." In addition, CAA section 172(c)(6) requires that nonattainment area SIPs "include enforceable emission limitations, and such other control measures, means or techniques . . . as well as schedules and timetables for compliance, as may be necessary or appropriate to provide for the attainment of such standard in such area by the applicable attainment date . . . ."  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.
   
 Stringency  -  Rules applicable in PM10 Moderate nonattainment areas must require Reasonably Available Control Measures (RACM) (see CAA §189). CAA §172(c) requires that RACM for nonattainment areas include "such reductions in emissions from existing sources in the area as may be obtained through the adoption, at a minimum, of reasonably available control technology . . . ." (RACT). Together, these two provisions require that areas of Moderate nonattainment for the PM10 NAAQS include RACM and RACT for existing sources of PM10 emissions.

 SIP Relaxation - CAA §110(l) prohibits the EPA from approving any SIP revision that would interfere with any applicable requirement concerning attainment and reasonable further progress (RFP) or any other applicable requirement of the CAA. In addition, CAA §193 prohibits the modification of any SIP-approved control requirement in effect before November 15, 1990, in a nonattainment area, unless the modification ensures equivalent or greater emissions reductions of the relevant pollutant(s).

       EPA EVALUATION - A summary of our evaluation of the three criteria follows:

    Enforceability  -  To help ensure enforceability, most MDAQMD Rule 401 provisions are sufficiently clear to ensure that affected sources and regulators can consistently evaluate and determine compliance with the rule. However, Rule 401 also contains a number of provisions that are potentially problematic to enforce. The key issues involve exemptions in Section (D), as described in "Rule Deficiencies."
   
    Stringency  -  The submitted rule is more stringent than the SIP. The proposed revision added equipment-specific visible emissions limitations, applicability, and test methods. We prepared a comparative analysis of visible emissions rules in local air districts regulating nonattainment PM areas in Attachment 1. Maricopa County, the San Joaquin Valley Air Pollution Control District, and the South Coast Air Quality Management District are in nonattainment for either PM2.5 or PM10. Like MDAQMD Rule 401, their rules each have an opacity limit of 20% not to exceed a period of three minutes in a 60-minute period and require the use of test method(s) promulgated in the Code of Federal Regulations for compliance verifications. MDAQMD Rule 401 additionally includes definitions and source-specific opacity limits. Based on the comparative analysis, we generally conclude that the submitted rule establishes RACM and RACT because the rule adopts limitations and applicability similar to or more stringent than other nonattainment areas. There are several exemptions in the Rule that may reduce the rule's stringency with respect to RACT that we are disapproving.
     
    SIP Relaxation  -  We propose to determine that our approval of the submittal would comply with CAA §§110(l) and 193 because (1) the proposed SIP revision would not interfere with any CAA requirements, including requirements for RFP and attainment of the NAAQS, and (2) the requirements in the submitted rule are more stringent than the existing SIP-approved control emission limit that they would replace.

RULE DEFICIENCIES  -  The following deficiencies in Section (D) Exemptions preclude full approval of the rule into the SIP:
 (D)(1)(b) exempts from Rule 401 visible emissions resulting from equipment breakdowns that comply with requirements in District Rule 430. District Rule 430 is not in the EPA-approved SIP Rule 430 because it contains exemptions inconsistent with long-standing national policy on requiring good engineering practices to prevent excess emissions at all times, including during startup, shutdown, and malfunction. Section 302(k) of the Clean Air Act requires continuous limitations on sources, even during breakdown events in Rule 401.
  (D)(1)(d) exempts from Rule 401 agricultural operations necessary for the growing of crops or raising of fowl or animals. This is an overly broad agricultural exemption. The MDAQMD should remove the broad exemption for agricultural operations or justify why it is appropriate to treat sources at agricultural operations differently than identical sources at non-agricultural operations.    
 (D)(1)(f) exempts from Rule 401 emissions from vessels using steam boilers during emergency shutdowns for safety reasons and operational tests. The MDAQMD has not defined "vessels," so it is unclear as to what sources this rule applies. Discussions with the District revealed that "vessels" likely refers to maritime vessels. The District believes there are no maritime vessels in the District that use steam boilers. If this provision does not apply to any sources in the District, the MDAQMD may remove it from Rule 401. Alternatively, the District should revise the provision to require good engineering practices be used to the fullest extent possible during startup and shutdown to minimize emissions.
 (D)(1)(h) exempts from Rule 401 emissions from vessels during a breakdown condition, as long as the discharge is reported in accordance with District requirements. The District requirements should be listed. As is, this exemption is inconsistent with long-standing national policy on requiring good engineering practices to prevent excess emissions at all times, including during startup, shutdown, and malfunction. Section 302(k) of the Clean Air Act requires continuous limitations on sources, even during breakdown events. The District should revise the provision to require good engineering practices be used to the fullest extent possible during breakdowns to minimize emissions. Additionally, the word "vessels" is undefined and it is unclear to what vessels this rule applies. The MDAQMD should define "vessels" to clarify what is regulated.
 (D)(1)(i) exempts from Rule 401 smoke emissions tepee burners during the disposal of forestry and agricultural residues or forestry and agricultural residues with supplementary fossil fuels when the emissions result from the startup or shutdown of the combustion process or from the malfunction of emission control equipment. The exemption does not apply to emissions which exceed a period or periods of time aggregating more than 30 minutes in any 24-hour period, nor to emissions which result from the failure to operate and maintain in good working order any emission control equipment. If this provision does not apply to any sources in the District, the MDAQMD may remove it from Rule 401. Alternatively, the District should revise the provision to require good engineering practices be used to the fullest extent possible during startup, shutdown, and malfunction to minimize emissions.
 (D)(1)(j) exempts from Rule 401 smoke emissions from burners used to produce energy and fired by forestry and agricultural residues with supplementary fossil fuels when the emissions result from the startup or shutdown of the combustion process or from the malfunction of emission control equipment. This exemption does not apply to emissions which exceed a period or periods of time aggregating more than 30 minutes in any 24-hour period, nor to emissions which result from the failure to operate and maintain in good working order any emission control equipment. The District should revise the provision to require good engineering practices be used to the fullest extent possible during startup and shutdown to minimize emissions.

EPA ACTION - The submitted Rule 401 strengthens the SIP by adding enforceable control requirements and test methods to determine compliance. The rule largely fulfills the relevant CAA §110 and part D requirements, but the deficiencies discussed above preclude full SIP approval. Therefore, EPA staff recommends a simultaneous limited approval and limited disapproval of Rule 401 pursuant to CAA §110(k)(3) and §301(a). 

REFERENCES 
    "Issues Relating to VOC Regulation Cutpoints, Deficiencies, and Deviations," (a.k.a., Bluebook) EPA OAQPS, May 25, 1988.
    "Guidance Document for Correcting Common VOC & Other Rule Deficiencies," (a.k.a., Little Bluebook), EPA Region 9, August 21, 2001.
    MDAQMD Rule 401, as amended August 26, 2019, and submitted to the EPA on January 8, 2021.
    San Joaquin Valley Air Pollution Control District Rule 4101, as amended February 17, 2005, and approved into the SIP August 11, 2005 (70 FR 46770).
    Maricopa County Air Pollution Control District Rule 300, Visible Emissions, as revised March 12, 2008, and approved into the SIP on July 28, 2010 (75 FR 44141).
    South Coast Air Quality Management District Rule 401, Visible Emissions, as adopted on March 2, 1984, and approved into the SIP on January 29, 1985 (50 FR 3906).

