Technical Support Document

for

EPA's Notice of Proposed Rulemaking

on revisions to the 

California State Implementation Plan 

as submitted by the State of California

for the Monterey Bay Unified Air Pollution Control District

EPA's Analysis of

Monterey Bay Unified Air Pollution Control District=s

Rule 400 - Visible Emissions

United States Environmental Protection Agency, Region IX

Air Division

January 2010

Prepared by Andrew Steckel
Monterey Bay UAPCD – Rule 400, 

Visible Emissions TSD, January 10

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Monterey Bay Unified Air Pollution Control District (MBUAPCD)

Rule 400 - Visible Emissions

1. Rule Adoption and Submittal Chronology - On August 11, 2005 (70 FR 46770), EPA 

incorporated into the SIP a version of MBUAPCD Rule 400 that was adopted locally on October 

15, 2003, and submitted to EPA on January 15, 2004. No subsequent version of the rule was 

submitted besides the December 15, 2004 version that is described below and is the subject of 

this technical support document.

- On December 15, 2004, the MBUAPCD Governing Board amended Rule 400. 

- On March 7, 2008, the California Air Resources Board (CARB) submitted the December 

2004 amended Rule 400 to EPA as a revision to the California State Implementation Plan 

(SIP).

- On April 17, 2008, EPA found complete California’s March 2008 submittal of Rule 400.

2. Rule Summary & Background - MBUAPCD Rule 400 is designed to limit visible emissions 

from various activities and sources, primarily by establishing a 20% opacity standard. The 

December 2004 amendment added a definition of “startup” in section 2.5 and relaxed the opacity 

requirement for gas turbines to allow 40% opacity during startup. Specifically, new section 3.2.3 

reads, “...visible emissions from gas-fired combustion turbines may exceed Ringlemann 1 during 

startup, provided that visible emissions during such startups shall not exceed Ringelmann 2 (or 

equivalent 40% opacity) for a period or periods aggregating more than three minutes in any one 

hour.” 

3. Nonattainment History of Monterey Bay Air Basin - Upon enactment of the Clean Air Act 

(CAA) Amendments of 1990, the Monterey Bay air basin was designated nonattainment for 

ozone and classified as moderate under CAA §107(d)(4)(B). However, on October 18, 2000, the 

area was designated attainment for the 1-hour ozone standard. The area also meets the 8-hour 

ozone standard, was designated attainment for PM-10, and meets the PM-2.5 standard. 

4. Rule Evaluation - EPA is primarily using the following three criteria to evaluate Rule 400.

a. Rule Stringency – CAA §§ 172(c) and 182(b)(2) require ozone nonattainment areas to 

implement reasonably available control technology (RACT) for ozone precursors. In approving

the Monterey Bay Ozone Maintenance Plan, EPA found that MBUAPCD had adequately 

implemented RACT. Because Monterey Bay attained the PM standard, the area was not subject 

to CAA §189 PM requirements regarding Reasonably or Best Available Control Measures 

(RACM or BACM).

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

approval must be clear and legally enforceable. 
Monterey Bay UAPCD – Rule 400, 

Visible Emissions TSD, January 10

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c. Anti-Backsliding - CAA §110(l) restricts certain SIP revisions that would relax existing SIPapproved requirements. 

EPA finds that Rule 400 reasonably fulfills these three criteria except for the rule deficiency 

identified below. 

5. Rule Deficiency - The SIP submittal fails to demonstrate that this rule revision adequately 

complies with CAA requirements regarding enforceability and anti-backsliding as described 

below. 

- New section 3.2.3 places no time limitation on opacity between 20% and 40% for gas turbines

except as defined in the District permit pursuant to new section 2.5. This is inconsistent with 

long-standing national policy on excess emissions (see attachment 8.c below), which explains

that SIP rules must ensure that emissions during startup conditions are minimized. We 

believe this could be addressed by adding rule text establishing appropriate time limitations on 

gas turbine startup, requiring sources to minimize time and emissions during startup, and 

demonstrating in the staff report that the rule minimizes emissions during startup.

6. Additional Recommendations for the Next Rule Revision - The following revision is not 

currently the basis for rule disapproval, but is recommended for the next time the rule is 

amended.

- Remove the broad exemption for agricultural operations at 1.3.3 or justify why it is 

appropriate to treat sources at agricultural operations differently than identical sources at nonagricultural operations.

7. EPA Action – EPA staff recommends full disapproval of the April 17, 2008 submittal of 

MBUAPCD Rule 400 pursuant to CAA §110(k) because the submittal would only weaken the 

SIP and the State has not shown that the submittal complies with the CAA in light of the 

deficiency described above. There are no CAA §110(c) FIP or §110(m) sanction implications of 

this action since this is not a required submittal. 

8. Attachments

a. MBUAPCD Rule 400 - Visible Emissions, adopted December 15, 2004.

b. “Staff Report; Proposed Revisions to Rule 400 (Visible Emissions)”, MBUAPCD, December 

15, 2004. 

c. “State Implementation Plans: Policy Regarding Excess Emissions During Malfunctions, 

Startup, and Shutdown”, USEPA Memorandum, September 20, 1999.