Response to Comments Document concerning the proposed use of

ASTM D6550 - 05 as an alternative test method for olefin content of gasoline On July 6, 2006, the American Petroleum Institute (API) petitioned the Agency to allow ASTM D6550 as an alternative test method for measuring the olefin content of gasoline. 1 The Agency agreed with this request, viewed API’s petition as non - controversial, and anticipated no adverse comments with API’s petition. On December 8, 2008, the Agency proposed, with a correspo nding direct final rule, to allow the use of ASTM D6550 - 05 as an alternative test method for olefin content in gasoline provided: 1) ASTM D6550 - 05 results were correlated to the designated test method, ASTM D1319 - 03 ε1 , and 2) users of ASTM D6550 - 05 make us e of the following conversion equation, Volume% = 0.857 X Mass% 2 , to convert mass percent olefins to volume percent olefins. In January, 2009, the Agency received an adverse comment from the N ew York State Department of Environmental Con serv ation (NY S DE C or DEC ). 3 On February, 6, 2009, the Agency published a partial withdrawal notice 4 of the direct final rule published on December 8, 2008, due to adverse comments submitted by NY S DEC. The following is a brief summary of the NYS DEC adverse comments and AP I’s responses to them . Comments:

1 See Air Docket # EPA-HQ - OAR- 2008 - 0558 - 0002. 2 This conversion equation was validated in ASTM D6550 for up to 10.5 weight percent olefins maximum in California gasoline meeting California Air Resource Board Phase 2 gasoline specifications. 3 See Air Docket# EPA-HQ - OAR- 2008 - 0558 - 0005. 4 74 FR 6233, February 6, 2009.2

NYSDEC argued that the use of ASTM D6550 - 05 would have the potential for producing results that are different from those produced with ASTM D1319 - 03 ε1 , and therefore , th at test results would not be consistent with EPA’s Co mplex Model. According to NYSDEC, a substantial volume of commercial gasoline has olefin content greater than 10.5 weight percent maximum for the proposed mass - to - volume conversion factor. Further, N YSDEC argued that t he EPA proposed mass percent to volu me percent conversion factor was not intended for universal use , that t he use of this conversion factor as proposed on December 8, 2008, may not be appropriate for all gasoline , and would therefore, have the potential to underestimate olefin content when a bove 10.5 weight percent.

On February 9, 2009, the American Petroleum Institute (API) responded to NYSDEC’s comment and asked the Agency to promulgate a rule that would allow ASTM D6550 - 05 as an alternative test method for olefins in gasoline. Thi s time, API requested the alternative test method, ASTM D6550 - 05, be correlated to the designated test method, ASTM D1319 - 03 ε1 , but without the use of the mass percent to volume percent conversion equation 5 as earlier proposed.

API stated that a test facility that chooses to use any EPA- allowed alternative test method must first develop a site - specific correlation of the allo wed alternative test method to the EPA- designated test method. According to API, i n the case of an olefin content site - specific

5 See Air Docket# EPA-HQ - OAR- 2008 - 0558 - 0007.3

correlation, the gasoline fuel set would span the olefin content range present and representative of the refinery or importer’s production. This gasoline fuel set would be analyzed by the test facility using both ASTM D1319 - 03 ε1 and ASTM D6550 - 05. A correlation equation would then be developed from the results of both of these test methods in terms of ASTM D1319 - 03 ε1 in volume percent versus ASTM D6550 - 05 in weight percent. Therefore , the applicable range of the resulting cor relation from a site - specific correlation would be consistent with the specific refinery’s olefin content range.

API also stated that if a test facility chooses to use an EPA- allowed alternative test method for analysis of a batch of gasoline, the labor atory would use the site - specific correlation equation as discussed previously to determine the designated test method value as if the gasoline sample had been analyzed by the EPA - designated test. In the case of the proposed ASTM D6550 - 05 alternative test method, it would be the ASTM D1319 - 03 ε1 determined olefin value as derived from the site - specific correlation equation that is reported to EPA on batch reports and used as an input to the EPA Complex Model. According to API, t he ASTM D6550 - 05 result in w eight percent would never be used directly for either compliance or as an input into the Complex Model for compliance demonstrations as described at 40 CFR Part 80.

Finally, API argued that there would be no need to convert olefin content measured by ASTM D6550 - 05 in weight percent to volume percent because the olefin result as determined by ASTM D6550 - 05 would be correlated to the designated test method, ASTM D 1319 - 03 ε1 ,4

based on a specific site’s gasoline production and , as previously stated, would never be used directly for either compliance or as an input to the Complex Model. Therefore , API recommend ed that EPA omit the initial conversion of ASTM D6550 - 05 weight p ercent to volume percent using the 0.857 factor and allow the use of ASTM D6550 - 05 as an alternative test method for olefin content in gasoline provided result s are correlated to the EPA- designated test method, ASTM D1319 - 03 ε1 .

On May 14, 2009, NYSDEC provided a response to API’s February 9, 2009 comments . 6 NYS DEC stated that the issue of the use of alternative test methods was discussed several times in the 1994 Reformulated Gasoline (RFG) Final Rule 7 . NY S DEC stated that in the 1994 RFG rule, “EPA s aw two issues with alternative test methods – accuracy and bias. Therefore, in order to evaluate an alternative test method, accuracy and bias must be the primary considerations. We believe that the concerns voiced by EPA in 1994 regarding multiple regul atory test methods are still valid today.” NYS DEC also noted that most comments to the 1994 RFG final rule were in favor or ASTM D1319 - 88 as the designated test method for the measurement of olefin content in gasoline despite the method’s inability to acc urately measure this property. They also added concerns about the precision of the designated test method and added that little progress has been made in improving this method.

6 See Air Docket# EPA -HQ - OAR- 2008 - 0558 - 0008. 7 (59 FR 7716, February 16, 1994)5

Further, NY S DEC reiterated its original comment that “ [t] he Complex Model was built using fuels analyzed for their olefin content using the designated FIA method. Therefore, the important factor is how well values determined by an alternative test method compare to those determined in the past by the designated FIA (ASTM D1319) me thod. Whether or not the SFC method (D6550 - 05) is more accurate, precise, inexpensive or otherwise desirable over the FIA method should not be the primary issue for this rulemaking. To the extent that the SCF [ sic] method gives results which are differen t (without regard to being better or worse) from those of the FIA, the calculated results of the Complex Model will be different.” NY S DEC further stated that “ [o] ur opposition to allowing ASTM D6550 - 05 as an alternative test method for ASTM D1319 is NOT b ased on a contention that ASTM D 1319 produced more accurate and precise estimations of the olefin content of gasoline. Our opposition is based on the fact that the algorithms used in EPA’s Complex Model were developed using olefin concentrations based so lely on ASTM D1319. Therefore gasoline regulatory programs which are dependent on the Complex Model are also dependent on ASTM D1319.” (Emphasis in original).

NYS DEC also argued that API’s new approach to allowing ASTM D6550 - 05 as an alternative test meth od for measuring the olefin content of gasoline has little resemblance to that which was originally suggested in their July 6, 2006 letter. Further, NYSDEC s tated that API’s new approach admits the 0.857 conversion factor for mass percent to volume percen t is not appropriate. According to NYSDEC, API now “suggest [s] a site - specific correlation” of FIA volume percent data and SFC mass percent data , a nd that w hile this was an improvement on6

their original suggestion, it wa s insufficient evidence for EPA to entertain ASTM D6550 - 05 as a proposed alternative test method.

NYS DEC also described the statement by API that “ a laboratory that chooses to use any EPA- allowed alternative test method must first develop a site - specific correlation of the EPAallowed, a lternative test method to the EPA- designated test method”, a s largely meaningless. According to NY S DEC, “any two sets of data can be correlated. Correlation is only the process of examining data to determine if there is a linear relationship and to deter mine that strength of that relationship.” NYS DEC also stated that, “API presented no data to support its contention that “a linear relationship was found to exist between FIA and SFC over the zero to 15 volume percent concentration range” and th at th e gr aphic is far too small to allow any analysis. NYSDEC also argued a lack of correlation because of API’s statement that “if needed, a nonlinear fit could easily be found to cover the zero to 20 volume percent range . ”

Finally, NYS DEC presented analysis of ASTM i nter- laboratory c rosscheck data , from January 2006 to October 2008 , on measurement of olefins in gasoline that used ASTM D1319 and ASTM D6550. According to NYSDEC, the analysis show ed that although the square of the correlation coefficient was very good and the slope of the line was close to unity, the overall line was a poor fit for data on olefin concentrations of below 5 volume percent. NY S DEC also present ed an analysis of data for olefin concentrations of 10 to 24 volume percent that indicated the linear fit was poorer and not ed that the slope of the least - squares linear- fit line7

wa s far from unity and the intercept very high. Finally, NYS DEC argued that while “calibration curves” of a single lab may appear better in terms of precision, there are no guarantees that any one lab would produce results that are more accurate than the average of a large number of labs subjected to statistical analysis.

On November 16, 2009, API provided a response 8 to NY S DEC’s May 14, 2009 letter. In regards to NYS DEC’s comment that there appears to have been little improvement in improving the FIA methods, API stated that the analytical instrument industry has given up attempts to improve the FIA method (ASTM D1319 - 03 ε1 ) because the FIA method has fundamentally poor precision, and because a better method, SFC (ASTM D6550 - 05), has been developed.

In regards to NYS DEC’s comment that “whether or not the SFC method is more accurate, precise, inexpensive, or otherwise desi rable over the FIA method should not be the primary issue for this rulemaking , ” API responded that ASTM test methods are constantly being updated and improved to be more accurate and precise. Round robin test programs are routinely conducted to quantify i mprovements in the methods’ precision statements. Both industry and government labs participate in ASTM round robin programs, as well as the ASTM inter- laboratory crosscheck data programs with a goal of improving the accuracy and site precision of their p articular labs. Also, a characteristic of world - class labs is that they use the 8 See Air Docket# EPA-HQ - OAR- 2008 - 0558 - 0009.8

most up -to - date test methods having the best accuracy and precision. According to API, t he purpose of EPA having allowed alternative test methods in the past has been to capt ure selected improvements in analytical technology and the concomitant improved operability, speed, accuracy, precision. Specific to olefin measurements, it is the uncertainty of the olefin measurements when using FIA that has led industry to develop the SFC method.

In regards to NYS DEC’s comment that, “to the extent that the SFC method gives results which are different from those of the FIA, the calculated results of the Complex Model will be different , ” API responded that this statement indicate d a misu nderstanding of how the Complex Model is used in regulati ng fuel s. According to API , this is because when an EPAallowed alternative test method is used , the alternative method result is translated into the “equivalent” result for the EPA- designated test method using the site - specific correlation required by EPA. It is the “equivalent” FIA result that is entered into the Complex Model, not the SFC result. “The test result from the alternative test method is never used directly for gasoline certification or for the Complex Model calculations. In addition, the test results using an alternative test method that has been well - correlated to FIA will be no more different from FIA that the difference between two repeat tests results obtained using FIA. ” (Empha sis in original).

I n regards to NYS DEC’s comment that their “opposition is based on the fact that the algorithms used in EPA’s Complex model were developed using olefin concentrations based9

solely on ASTM D1319. Therefore gasoline regulatory programs whi ch are dependent on the Complex Model are also dependent on ASTM D1319 , ” API respon se was that “ [i] f such logic were followed, progress would have stopped long ago. We would still be required today to use the version of each ASTM test method that was used to obtain the data for development of the Complex Model. For example, we would be required to use ASTM D323 for measuring gasoline vapor pressure, which was abandoned in 1991 when ASTM D5191 was adopted in 1992. Also, the ASTM standard specification for gasoline would be a very outdated D439 rather than today’s D4814. And, we’d be stuck with a 1990 vintage vehicle fleet for our driving needs because that is the technology that the Complex Model is based upon.”

In response to NYS DEC describing API’s sta tement that “ [a] laboratory that chooses to use any EPA- allowed alternative test method must first develop a site - specific correlation of the EPA- allowed, alternative test method to the EPA- designated test method , ” as “largely meaningless” API responded th at “ NY S DEC appears to be unaware that except for the diesel rule where EPA adopted a performance based approach in approving diesel sulfur test methods, EPA has required that any lab that wishes to use an EPA- allowed alternative test method must develop an d maintain such a site - specific correlation. The correlation requirement for each of the nine alternative test methods currently allowed by EPA is not meaningless, but rather a federal EPA requirement.”10

API responded to NYS DEC’s comment that “API present s no data to support the statement that a linear relationship was found to exist between FIA and SFC over the zero to 15 volume percent concentration range ” by stating tha t “Figure 1 in the July 6, 2006 API letter is reproduced below to demonstrate the lin earity of the matter over the zero to 15 volume percent range. Note that the results in this plot include the use of the 0.857 factor only because we chose to reproduce the original plot shown in the July 6, 2006 letter. The use or omission of the conver sion factor makes absolutely no difference in any conclusions regarding the linearity of the data.”

In regard to NYS DEC’s comment that “EPA’s lab would not be able to test fuels because correlations will be refinery- [specific] and laboratory- specific. Th erefore, enforcement will be hindered as EPA would not be able to recreate the correlations used , ” API stated that “EPA’s enforcement of its fuel standards is completely independent of the EPA- allowed alternative test methods being used by labs, as well as related site - specific correlations. Whereas EPA may use non - designated test methods for screening purposes on occasion, we understand that all EPA enforcement is based on measurements obtained using EPA- designated test methods.”

In regard to NYS DEC co mment that t he y also ha ve issues with how ASTM analyzes round robin program data and inter- lab crosscheck data using “robust statistics , ” API responded that “the ASTM statistical package used to analyze the data has been peer reviewed and accepted by sta tisticians in industry and governments across the globe.”11

Further, API noted that NYS DEC’s May 14, 2009 letter, persist ently refer red to the API February 9, 2009 letter as a “new proposal . ” As one example they cite d NYSDEC’s statement that “API’s newl y suggested method has little resemblance to that which they originally suggested in their July 6, 2006 letter. API’s new approach admits that the 0.857 conversion factor for mass percent to volume percent is not appropriate.” In response, API notes that their February 6, 2009 letter, recommended that the EPA regulation omit the initial conversion of the D6550 weight percent to its volume percent using the 0.857 factor. A ccording to API, a s explained in that letter, the use or omission of the conversion factor would make absolutely no difference in any reported olefin result in the proposed rule. Finally, API recommend ed again that EPA allow ASTM D6550 - 05 as an allowed alternative to the designated test method, ASTM D1319, for measuring olefin content of gasoline, provided the results are correlated with ASTM D1319 using a refinery- specific correlation of FIA (volume %) versus SFC (weight%).”

EPA Response to API & NYDEC comments :

In today’s action, EPA is proposing to allow ASTM D6550 - 05 (SFC) as an al ternative to the designated test method, ASTM D1319 - 03 ε1 (FIA), for measuring olefin content of gasoline, provided the results are correlated to ASTM D1319 - 03 ε1 using a site - specific correlation of FIA (volume percent) versus SFC (weight percent). The Age ncy is also proposing that correlation be12

completed on a site - specific basis. The Agency believes it is in a test facility’s best interest to ensure that the gasoline fuel set used to develop the correlation spans the range of olefin properties representa tive of that refinery’s or importer’s gasoline production. This gasoline fuel set would be analyzed by the test facility’s laboratory using both ASTM D1319 - 03 ε1 (also known as FIA, or the designated test method) and ASTM D6550 - 05 . A resulting correlation equation would then be developed in terms of ASTM D1319 - 03 ε1 in volume percent and ASTM D6550 - 05 in weight percent. Thus, the applicable range of the result ing correlation from a facility’s site specific correlation would be consistent with that specific facility’s olefin content range. Furthermore, the requirement of correlating SFC test methods results to the FIA designated test method produces an SFC - FIA equivalent result that is suitable for input into the Complex Model or for meeting fuel reporting requirements . The Agency agrees with API’s recommendation that there is no need to convert olefin content measured by ASTM D6550 - 05 in weight percent to v olume percent because the olefin result as determined by SFC (ASTM D6550 - 05 ) is correlated to FIA ( ASTM D1319 - 03 ε1 ) based on a specific site’s production and never used directly for compliance or as an input into the Complex Model. Thus , in today’s propos al, EPA is omitting the initial conversion of olefin content measured by ASTM D6500 - 05 in weight percent to volume percent using the 0.857 factor, as earlier proposed on December 8, 2008 .13

The Agency agrees with NYS DEC that a bias in gasoline olefin measur ement results may exist between ASTM D1319 - 03 ε1 and ASTM D6550 - 05 . In order to compensate for any bias that may exist between these two analytical test methods, EPA is proposing to require ASTM D6550 - 05 to be correlated to ASTM D1319 - 03 ε1 , its respective designated test method. Refiners or importe rs that choose to use ASTM D6550 - 05 for the measurement of olefin content in gasoline must report the correlated result, on a site - specific basis, with the designated method, ASTM D1319 - 03 ε1 , when using the proposed EPA - allowed alternative test method, AST M D6550 - 05.

The agency also notes that Figure 1 from API’s July 6, 2006 letter illustrates a confidence plot from ASTM standard practice ASTM D6708 for ASTM D6550 vs. ASTM D1319. The fuels samples used in the ASTM crosscheck program were provided to ASTM on a global basis, not from a specific refinery. The Agency believes that because the fuel samples provided to ASTM for their crosscheck program are provided to ASTM on a “global ” basis, one would expect that these fuel samples would vary in olefin co ntent more than if they were provided from a specific refinery. Thus , the ASTM D6708 confidence plot using ASTM crosscheck data represents a robust data set compared to if the same confidence plot were derived from a specific refinery. The Agency also be lieves that API’s intent i n using this illustration was not to establish a

“global ” linear correlation between these two methods, but to show that a linear relationship could be established between these two methods using a robust fuels data set on olefin content from the ASTM c rosscheck program. The Agency believes that this illustrati on of a14

linear relationship between SFC and FIA from the ASTM crosscheck program is sufficient evidence to illustrate that a linear relationship may be established between these two test methods. Moreover, if a linear relationship can be established betwe en two analytical test methods with fuel samples representing producers on a “global ” scale, then one would expect that a linear relationship may be established between these two test methods on a site specific basis , where olefin content variance in gasol ine fuel samples would not be expected to be as varied, compared to fuel samples from an ASTM crosscheck program.

The Agency does not believe that the adoption of alternative test methods for compliance measurements hinders its enforcement ability. Ra ther, the Agency believes that t he adoption of alternative test methods used for compliance measurement provides flexibility to the regulated industry by allowing methods that may be less expensive, increase speed of analysis, or may be more accurate or pr ecise . We also believe that our approval of this alternative test method would not be inconsistent with the Agency’s posture in the RFG rule. This is because, a s discussed previously, the requirement of correlating EPA - allowed alternative test method res ults to its respective designated test method compensates for any bias that may exist between the alternative and designated test method. Additionally, as also previously discussed, the liner relationship would likely assure accuracy. Moreover, while th e Agency may use non - designated test methods for enforcement screening purposes, it uses the designated test method specified in the regulations for each particular fuel parameter for purposes of enforcement.15

Further, we believe today’s proposal is consi stent with past Agency practice because t he Agency currently allows eight alternative test methods for the measurement of gasoline or butane properties provided their results are correlated to the fuel parameter’ s respective EPA designated test method. Th ese alternative test methods are: ASTM D5453, ASTM D6920, ASTM D3120 and ASTM D7039 for sulfur in gasoline 9 , ASTM D4468 and ASTM D3246 for sulfur in butane 10, ASTM D1319 for aromatics in gasoline 11 , and ASTM D4815 for oxygenate content of gasoline. 12 In addi tion, ASTM D4294, ASTM D6920 and ASTM D5453 are approved alternative test methods for measuring the sulfur content of 500 ppm diesel fuel provided its test results are correlated to the designated test method, ASTM D2622. 13

Finally, although not the subj ect of this proposed rulemaking, EPA intends to establish a performance - based test method approach (PBTM) rule which would provide criteria for the qualification of alternative test methods.

9 See 40 CFR § 80.46(a)(3)(i) through § 80.46(a)(3)(iv). 10 See 40 CFR § 80.46(a)(4)(i) through § 80.46(a)(4)(ii). 11 See 40 CFR § 80.46(f)(3)(i). 12 See 40 CFR § 80.46(g)(2)(i). 13 See 40 CFR § 80.580(c)(2).