


                                       
                 UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
                            REGION IX AIR DIVISION




                          Technical Support Document 
                                      for
                              EPA's Rulemaking
                                    for the
                     California State Implementation Plan
                                       
             Yolo-Solano Air Quality Management District Rule 2.34
                            Stationary Gas Turbines




                              
                            Prepared by: Kevin Gong
                               November 10, 2015





RULE IDENTIFICATION 
Agency
Yolo-Solano Air Quality Management District  (YSAQMD)

SIP Approved Rule
Rule 2.34  -  Stationary Gas Turbines
Adopted - July 13, 1994 
Submitted  -  September 28, 1994
EPA Approved  -  September 3, 1998 (63 FR 46892)

Subject of this TSD
Rule 2.34  -  Stationary Gas Turbines
Revised  -  November 12, 2014
Submitted - June 26, 2015

Completeness Finding
Determined Complete  -  August 13, 2015


BACKGROUND 
YSAQMD regulates a portion of the Sacramento Metropolitan Air Basin, which is classified as a "Severe" nonattainment area (NAA) for the 2008 8-hour ozone National Ambient Air Quality Standard (NAAQS) (see 40 CFR part 81). For areas classified as moderate nonattainment or above, the Clean Air Act (CAA) requires that the State must submit provisions to the State Implementation Plan (SIP) to require implementation of reasonably available control technology (RACT) (see sections 182(b)(2) and 182(f)).  This rule is intended to implement RACT-level controls for stationary gas turbines, and was revised recently partly to include new limitations on emissions during start-up and shut-down periods, and during short-term exceedances under specific circumstances. 

RULE SUMMARY 
Rule 2.34 establishes limits for NOx emissions and for stationary gas turbines.  It also describes related recordkeeping, reporting, and monitoring requirements.  The District was prompted to revise the rule after an operator applied to construct a combined cycle gas turbine, as the SIP approved rule's requirements did not take into consideration the different operating needs for combined cycle systems.  The operator for the proposed combined cycle plant chose to cancel their project shortly thereafter.  There is only one simple cycle gas turbine facility in the district.  Changes from the approved SIP rule include:

1.	Deletion of an exemption for pipeline gas turbines. 

2.	Updated definitions to support new and changed provisions in the rest of the rule.

3.	Removal of references to efficiency factors in compliance limits for turbines generating more than 2.9 megawatts, and references to biogas and digester gas for fuel.

4.	New operating requirements for control equipment and average limits during start up periods.

5.	New requirements that all turbine operators maintain continuous monitoring equipment and revised source testing requirements.

6.	Separate reporting requirements for gas turbines defined as exempt elsewhere in the rule, and for gas turbines that are covered by this rule.

7.	Deletion of outdated compliance schedules and other obsolete language.

8.	Other minor formatting and editorial revisions to improve clarity.

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.  In addition, we refer to Restatement to Update of EPA's SSM Policy Applicable to SIPs (80 FR 33839, June 12, 2015), with respect to emissions during start-up, shut-down and malfunction (SSM) conditions discussed in Rule 2.34 paragraph 302.  In general, this EPA policy clarifies the requirement for continuous emission limitations, consistent with the CAA.

      2.	Stringency - SIPs must require RACT for each category of sources covered by a Control Technique Guideline (CTG) document as well as each major source in ozone nonattainment areas (see sections 182(b)(2) and 182(f)). While there is no CTG for this source category, EPA has published an Alternative Control Techniques (ACT) document titled, "NOx Emissions from Stationary Gas Turbines" (EPA 453/R-93-007, January 1993) which describes available control techniques and their estimated costs. This ACT and other state and local rules for this category were used to help evaluate the RACT requirements of CAA §182(b)(2) and §182(f).  

      3.	SIP Relaxation - CAA §110(l) prohibits 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.
      
EPA EVALUATION 
A summary of our evaluation of the three criteria follows.

      1. 	The provisions of Rule 2.34 clearly define the types of turbines that must comply with this rule.  Requirements are clearly written, and the monitoring, recordkeeping, and reporting provisions will sufficiently ensure that any affected sources can maintain compliance against the outlined limits.
      
      	The previous version of Rule 2.34 exempted SSM emissions from control measures, but the most recent revision removes the exemption and replaces it with new restrictions during SSM events.  During start-up and shut-down events, selective catalytic reduction control systems now must be activated once a minimum temperature is achieved based on manufacturer recommendation or source test data (this minimum temperature must be no higher than 550 degrees Fahrenheit).  Additionally, start-up and shut-down emissions are limited to 70 ppmv NOx for gaseous fuels, and 226 ppmv NOx for liquid fuels.  During normal operating conditions, short-term excursions (up to 4 consecutive 15 minute periods) over the compliance limits are now allowed.  However, such excursions must not exceed the normal operating limits described in the table in section 301, as measured over a 6 hour rolling average, and there shall be no more than 10 hours of exceedance in a year.  Such restrictions have the practical effect of requiring continuous compliance with emission limits, even when there are excursions over the normally applicable limits. We believe that these provisions comply with EPA's recently updated policy by establishing reasonable continuous emission limitations during SSM events.
      
      2. 	The submitted rule requirements are similar to analogous requirements in other parts of California that generally have among the most stringent requirements nationwide, including SMAQMD Rule 413, Antelope Valley Air Quality Management District (AVAQMD) Rule 1134, and South Coast Air Quality Management District (SCAQMD) Rule 1134.  There is no national CTG guidance for gas turbines to help define RACT, but  Rule 2.34 is more stringent than EPA's 1993 ACT  and applicable New Source Performance Standards, such as "Standards of Performance for Stationary Combustion Turbines" (40 CFR 60 Subpart KKKK).  As a result, we propose to determine that this rule fulfils RACT requirements.

      3. 	During YSAQMD's development of most recent revisions to Rule 2.34, a turbine manufacturer commented that turbines burning alternative gaseous fuels such as digester or landfill gasses could potentially have higher emissions due to their different combustion qualities and characteristics. The District agreed, and revised the definition of "gas" fuels to include commercial natural gas and liquefied petroleum gas, but not digester and landfill gases.  As there are no turbines fired on these alternative gaseous fuels in the District, this does not relax the rule in a way that is inconsistent with CAA §§110(l).  Other rule revisions, including a requirement that operators install continuous emissions monitoring equipment in section 303, a requirement for 3 party testing in section 304, and longer recordkeeping requirements in section 502, would strengthen the SIP-approved version of the rule.
      
      	As a result, 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 the on-going process for ensuring that requirements for RFP and attainment of the NAAQS are met, and (2) the emission limits in the submitted rule are not less stringent than the existing SIP-approved rule.

RULE DEFICIENCIES 
There are no deficiencies in this rule that would preclude full approval into the SIP.

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: 

1.	While there are currently no turbine units in the District that are fired on digester gas or landfill gas, the rule would be strengthened by including concrete limits for units using these fuels, even if they are higher limits.

EPA ACTION
The submitted Rule 2.34 strengthens the SIP by, among other changes, placing new restrictions on emissions during SSM events.  The rule largely fulfils the relevant CAA §110 and part D requirements.  Therefore, EPA staff recommends approval of Rule 2.34 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 (http://www.epa.gov/ttn/naaqs/ozone/ozonetech/voc_bluebook.pdf).
 "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).
 Letter dated June 26, 2015, from Richard Corey, Executive Officer, California Air Resources Board, to Jared Blumenfeld, Regional Administrator, US EPA Region 9, with enclosures including "Proposed Amendments to Rule 2.34, Stationary Gas Turbines  -  Final Staff Report" and other SIP submittal documents.
 "Restatement to Update of EPA's SSM Policy Applicable to SIPs," 80 FR 33839, June 12, 2015. .
 AVAQMD Rule 1134, Emissions of NOx from Stationary Gas Turbines, as adopted on January 19, 2010, and approved into the SIP on January 18, 2012 (77 FR 2469). 
 SMAQMD Rule 413, Stationary Gas Turbines, as adopted on March 24, 2005, and approved into the SIP on January 10, 2008 (73 FR 1819).
 "Alternative Control Techniques Document  -  NOx Emissions from Stationary Gas Turbines," (EPA-453/R-93-007), Emissions Standards Division, EPA OAQPS, January 1993.
 Comment letter correspondence between Nicole Law and Andrew Steckel, US EPA to Paul Hensleigh, on February 6, 2014, April 18, 2014, June 4, 2014 and July 30, 2014.
