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C A M B R I A <br /> are in active remediation and using an insitu technology that may alter(break down) the methyl <br /> tertiary butyl ether (MTBE) molecule into other compounds. An example of this type of <br /> technology is ozone sparging. This type of treatment technology oxidizes MTBE and may result <br /> in breakdown products of known compounds or perhaps some unknown compounds. These <br /> unknown compounds are of concern for the CVRWQCB, which is the reason they request the <br /> 'report all peaks'analysis in this situation." <br /> Based on the information outlined above that was provided to Cambria by the CVRWQCB, an <br /> EPA Method 8260 peaks report is not warranted at this site. Cambria requested that SJCEHD <br /> © withdraw this request in the letter referenced above. To date, we have not received a response <br /> from SJCEHD. <br /> MTBE Hydrolysis <br /> In the March 21, 2003 letter, SJCEHD expresses concern about the "...potential hydrolysis of <br /> MTBE to TBA [tertiary butanol] and methanol in groundwater samples" and requests that Shell <br /> "...collect split samples for at least two quarters, with one group using an acidic preservative, <br /> and the other using a base, trisodium phosphate(TSP)." An EPA Fact Sheet entitled Analytical <br /> Methodologies for Fuel Oxygenates (EPA 510-F-03-001) dated April 2003 (included as <br /> Appendix A) advocates using TSP as a sample preservative when samples arc heated to an <br /> elevated temperature (80°C) during preparation or analysis. Research cited in Oxygenate <br /> Measurements in Groundwater. Do We Need to Worry About MTBE Acid Hydrolysis? (Bauman, <br /> 2003) also suggests that the combination of a low-pH sample preservative and elevated heat <br /> during sample preparation or analysis can lead to MTBE hydrolysis to TBA. However, this <br /> article also demonstrates that the amount of TBA produced by hydrolysis is insignificant in acid- <br /> preserved samples if the samples are only heated to 45°C or less. This article is provided as <br /> Appendix B, and two additional articles that are discussed in the Bauman article (including a <br /> case study)are included for your reference as Appendix C. <br /> Shell's laboratory only heats the groundwater samples to 45°C for oxygenate analyses. <br /> Therefore, because the sample temperature is kept appropriately low, it is not necessary to use <br /> TSP as a sample preservative to prevent MTBE hydrolysis to TBA, and Shell respectfully <br /> declines to collect split samples and conduct a study of sample preservatives at this site. <br /> 0955 4 <br />