Dynamic underground stripping: steam and electric heating for in situ decontamination of soils and groundwater

US5449251A · kind A · utility

Assignee

• The Regents of the University of California · US

Inventors

• William D. Daily · Livermore, US
• Abelardo L. Ramirez · Pleasanton, US
• Robin L. Newmark · Livermore, US
• Kent S. Udell · Berkeley, US
• Harley M. Buetnner · Livermore, US
• Roger D. Aines · Livermore, US

Key dates

• Filing date: May 4, 1993
• Grant date: Sep 12, 1995
• Expiry date: May 4, 2013

Classification

• Technology area (CPC B): Performing Operations; Transporting
• CPC primary: B09C2101/00
• WIPO field: Civil engineering
• WIPO sector: Other fields

Abstract

A dynamic underground stripping process removes localized underground volatile organic compounds from heterogeneous soils and rock in a relatively short time. This method uses steam injection and electrical resistance heating to heat the contaminated underground area to increase the vapor pressure of the contaminants, thus speeding the process of contaminant removal and making the removal more complete. The injected steam passes through the more permeable sediments, distilling the organic contaminants, which are pumped to the surface. Large electrical currents are also applied to the contaminated area, which heat the impermeable subsurface layers that the steam has not penetrated. The condensed and vaporized contaminants are withdrawn by liquid pumping and vacuum extraction. The steam injection and electrical heating steps are repeated as necessary. Geophysical imaging methods can be used to map the boundary between the hot, dry, contamination-free underground zone and the cool, damp surrounding areas to help monitor the dynamic stripping process.