UNITED STATES ENVIRONMENTAL PROTECTIONAGENCY REGION IX 75 Hawthorne Stmet San Francisco, CA 94105 March 

### 31,1999

Ms. Elaine Chang Assistant Deputy Executive Officer Office of Planning, Rule Development and Area Sources South Coast Air Quality Management District 2 1865 E. Copley Drive Diamond Bar, CA 9 1765-4 182 Subject: Review of Proposed Amended Rule 218 and Proposed Rule 2 18.1 Dear Ms. Chang: Thank you for the opportunityto comment on proposed amended Rule 2 18 (PAR 2 18

## - December 11, 1998)and proposed Rule 218.1 (PR 218.1 

## - no date). In your letter of September24, 1998, you requested EPA review PAR 2 18 and PR 2 18.1, particularly in "how EPA might perceive the currently proposed absolute de-minimus concentrationperformance specification for Relative Accuracy ...[ and] would EPA state that the requirements for PR 2 18.1 are equivalentto 40 CFR 60 requirements for Title 

### V purposes, and therefore federally enforceable." EPA considers that at medium to high emission limits, PR 21 8.1's relative accuracy criteria are equivalent to or are more stringentthan the federal standards. However, at very low emission limits, (e.g., at less 

### than 5 ppm for NOX limits), PR 218.1's relative accuracy criteria becomes less stringentthan the federal limits. EPA recognizes, however, that relative accuracy values at very low levels, such 

### as less than lppm, may not be meaningful due to limitations of current technology. The enclosure provides additional commentsto PAR 2 18 and PR 2 1 8.1. EPA welcomesthe opportunityto review PAR 2 1 8 and PR 2 1 8.1. If you have any questions about these comments, please do not hesitate to call me at (4 15)744-1 185 or Stanley Tong of my staffat (4 1 5) 744-1191.

Enclosure cc: John Higuchi, SCAQMD



# . Cindy Castronovo, CARB Andrew Steckel Chief, Rulemaking OfficeComments to South Coast Proposed Amended Rule 218 and Proposed Rule 218.1

General Comment 

### 1. Absolute de-minimus Value for Relative Accuracy EPA considers that at medium to high 

### emission limits, PR 218.1's relative accuracy criteria are equivalent to, or are more stringentthan the federal standards. However, at very low emission limits, (e.g., at less than 

### 5 ppm for NOX limits), PR 21'8.1's relative accuracy criteriabecomes less stringent than 

### the federal limits. EPA recognizes that relative accuracy values at very low levels, such as less than 

### 1ppm, may not be meaningfbl due to limitationsof current technology. These limitationsinclude the availability and accuracy of low concentration protocol calibration gases and the degree ofprecision of the reference test methods at low concentrations. Therefore, EPA does not object to PR 2 18.1'suse of an absolute de-minimus value. Approvability Issues 

### 1. Full Span Range South Coast should add language to the rule on how to handle spikes. Such language should indicate that if a value falls outside the acceptable 

### 111span range, the value is not valid for quantificationbut must be reported and that the spike may be considered 

### a violation ofthe standard depending on the conditions under which the spike occurred. 

### 2. Clarifications

a. Alternative Sampling Locations: PAR 2 1 8.1 @age2 18.1

### - 10,top ofpage) allows the Executive Officer to evaluateand approve alternate shplinglocations. South Coast should clarify in the rule, the hierarchy that will be 

### used to evaluate and approve alternate sampling locations including referencing any applicable guidance document such as Emission Measurement Center (EMC) guidance. b. Full Span Range: PAR 2 18.1 @age 2 18.1 -,lo,para (c) (ii)) allows an alternate full span range (from the 150-200%of concentration limit) to be approvedby the Executive Officer. South Coast should specify acceptable conditions which would warrant going outside ofthe full span range.

c. Alternative CertificationMethods: PAR 2 18.1 @age 2 18.1-1 

### 9, para (d)(l)(A)) allowsthe Executive Officer to approve alternative certificationmethods for low concentration gases such as 10 ppm NOX or CO. South Coast should clarify in the rule, the hierarchy that will be used to evaluate and approve the alternative certification methods.

### Comments to South Coast Proposed Amended Rule 218 and Proposed Rule 218.1

3. Response time PAR 21 8.1 (page 2 18.1-14 para (3)(A) and page 218.1-18 para (c) (l)(C)) states the response time for all analyzers and flow monitors shall not exceed 5 minutes for any new or modified CEMS and shall not exceed 10minutes for existing CEMS. 40 CFR 60, Appendix A, Performance Spec 4A for CarbonMonoxide specifies a response time of 1.5 minutes. The reason for this short response time is to capture CO spikes which may be present, especially from Municipal waste combustors. Longer response times may not capture CO spikes. Unless there is a technical limitation, South Coast should include this shorterresponse time for CO CEMS. 

### Recommendations: 1. QNQCplan: PAR 218. EPA recommends that for facilities who choseto continue to operateunder the existing CEMS option, that QNQCplans be developed and implemented within 1 year of the promulgation date ofthe rule. The QNQCplan should be maintained on site and be made available for inspection upon request by District personnel. 2. Record Retention: PAR 218 (page 218-17 para (e) (1)) states that records shall be maintained for a minimum period of two years or as specifiedby the applicable rule or regulation. EPA recommends a five year record retentionperiod rather than the two year period 

### in the rule. This would make the record retention period consistent with the statueof limitations. 

### 3. The rule is silent on quarterly cylinder gas audits. EPA strongly recommends that a quarterly cylinder gas audit be required.