Changes in geotechnical properties of soil contaminated by methyl tertiary butyl ether (MTBE)

Abstract

As one of the extensively used gasoline additives, MTBE can leak into the subsurface, which will not only deteriorate the ecological environment, but also affect the geotechnical characteristics of the soil. In this study, the geotechnical properties of MTBE-contaminated soil consisting of the basic physical properties, strength, compressibility, hydraulic conductivity, leachability, electrical resistivity and microstructural characteristics are comprehensively investigated. The results show that the Atterberg limits consistently decrease with increasing MTBE content in the soil. As the MTBE content increases from 0% to 10%, the specific surface area of the soil decreases by 28%, the sand content increases by 22%, the clay and silt contents decreases by 3% and 18%, respectively. The soil compression index, hydraulic conductivity, leached MTBE concentration and electrical resistivity increase, while the UCS decreases with increasing the MTBE content. Microstructural analysis shows that increasing MTBE content would result in mineralogical alterations that decrease the illite and kaolinite content in the soil. The aggregation and flocculated structures could be detected with an increase in the number and size of the inter-aggregate pores. Additionally, electrical resistivity of the contaminated soil is adopted to assess the geotechnical properties of MTBE-contaminated soil based on the well-established empirical relations.