Reformulated Gasoline Transport and Clean-up of Spills to the SubsurfaceEPA Grant Number: R821114
Title: Reformulated Gasoline Transport and Clean-up of Spills to the Subsurface
Investigators: Powers, Susan E.
Institution: Clarkson University
EPA Project Officer: Hiscock, Michael
Project Period: October 1, 1995 through September 30, 1998 (Extended to September 30, 1999)
Project Amount: $240,479
RFA: Exploratory Research - Chemistry and Physics of Water (1995) RFA Text | Recipients Lists
Research Category: Water , Land and Waste Management , Engineering and Environmental Chemistry
Description:The overall goals of this project are to: (1) provide a better understanding of the effects of gasoline additives on the fate, transport and remediation of reformulated gasolines in subsurface environments, and (2) identify better sorbents for cleaning groundwater contaminated by reformulated gasoline to drinking water quality standards. Two specific types of gasoline additives in reformulated gasoline are of concern: oxygenates, such as ethers and alcohols, due to their impact on the solubility of carcinogenic and potentially carcinogenic species from the gasoline; and deposit control additives and detergents due to their potential for adsorption to soil minerals, thereby affecting the soil wettability. Both of these types of additives lower gasoline-water interfacial tensions as well. Changes in the wettability and interfacial tension will impact the capillary nature of the multiphase fluid flow processes, and the increased solubility could cause greater exposure and human health risks associated with drinking water contaminated by reformulated gasoline.
Both experimental and mathematical modeling approaches will be used to meet the objectives of this project. A range of experiments will be carried out to measure properties of the reformulated gasoline-water system, such as solubility and interfacial tension, that affect multiphase flow and fate processes. Larger scale experiments will include quantification of the rates of dissolution of soluble and slightly soluble contaminants from the gasoline, capillary pressure curves and recovery tests. A second phase of the research work will include measuring adsorption isotherms to identify sorbents that are suited for removal of both polar and nonpolar contaminants from contaminated waters. Results from each of the experiments will be incorporated into mathematical models of the processes and used for predicting the behavior of these fuels in the subsurface or the removal of these substances from drinking water.
The occurrence and effects of gasoline oxygenates in the environment is a significant concern of both research and regulatory communities due to the increased use of these gasolines under the Clean Air Act Amendments of 1990. The fate of reformulated gasolines in the subsurface must be understood to adequately assess risks to aquifer water quality and human health. From an engineering perspective, it is only wise to take a proactive approach in finding solutions to the problems associated with spills of reformulated gasoline. Ethers used as oxygenates are already impacting a large number of wells. An assessment of drinking well water quality by the NAWQA Program indicated that 14% of the 540 wells sampled had detectable concentrations of methyl tert-butyl ether; many of these are private drinking water supplies. It is critical to develop a simple yet effective treatment technology for these types of wells. Adsorption has been the standard technology for removing organic compounds from private water supplies. Identifying a better sorbent for these systems could reduce risks associated with drinking water contaminated by oxygenated fuels.