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1D - Soil and Sediment Contamination (TUP/3) TBA/MTBE Remediation Seminar. Jansen, Ron1, Moyer, Ellen2, Woodward, Richard3, Greene, Jonathan4, Sloan, Richard5, 1 Remedial Operations Group, Inc., Crosby, Texas, USA2 Tighe & Bond, Inc., Westfield, Massachusetts, USA3 Sierra Environmental Services, Inc., Houston, Texas, USA4 Malcom Pirnie, Houston, Texas, USA5 Lyondell Chemical Company, Channelview, Texas, USA ABSTRACT- Tert Butyl Alcohol (TBA) is often found with Methyl tert Butyl Ether (MTBE) in environmental samples of gasoline-impacted sites. TBA is a fuel oxygenate, is an unreacted co-product present at low percent levels in commercial MTBE, is an intermediate product of MTBE biodegradation and chemical oxidation and is an artifact created during certain sample preservation and analytical procedures. TBA/MTBE physical characteristics of solubility, adsorption coefficient, vapor pressure and Henry′s constant differ significantly from other gasoline hydrocarbons and influence the selection and optimization of both traditional and innovative remedial options for residual and dissolved constituents in the field. Demonstrated effective technologies include: soil vapor extraction; air sparging; pump and treat; in situ/ex situ ground water bioremediation; in situ/ex situ chemical oxidation; bioventing; and monitored natural attenuation. Pure cultures of aerobic TBA/MTBE degrading microorganisms have been commercialized for both in situ and ex situ site remediation. Anaerobic mineralization of TBA/ MTBE by mixed cultures in the field has also been demonstrated with other electron acceptors including nitrate, iron, sulfate and carbon dioxide. Biodegradation is an important mechanism for natural attenuation of TBA/MTBE and the primary reason why TBA/ MTBE plumes eventually stabilize and attenuate. Remediation of gasoline-contaminated soil and groundwater is typically driven either by benzene (due to its toxicity) or MTBE (due to its high concentration in reformulated gasoline and its aesthetic impact on drinking water). For the latter, taste and odor concerns, rather than health effects, determine cleanup levels. US EPA established drinking water guidelines for MTBE of 20-40 ug/L. Several states have also established guidelines for TBA. This seminar presents remedial strategies and case studies that exploit unique site conditions and the physical characteristics of TBA, MTBE and other gasoline components for effective site remediation. The sequence of actions, starting with receptor protection and source control, followed by remediation of residual and dissolved contamination, and ending with natural attenuation, provides for environmentally sound, timely, and cost-effective TBA/MTBE remediation. Key words: tertiary butyl alcohol, methyl tertiary butyl ether, fuel oxygenate, reformulated gasoline |
