Six Phase Heating: A case study of in situ DNAPL remediation at a former manufacturing site
Current Environmental Solutions, in partnership with ENSR, is using the Six-Phase Heating{trademark} technology to remediate DNAPL pools of trichloroethylene (TCE) and 1,1,1-trichloroethane (TCA) at a former telecommunications manufacturing facility in Skokie, IL. From 1991 to early 1998, ENSR had been performing soil and groundwater remediation using a process of combining steam injection with soil vapor extraction. The steam injection process was able to remove much of the DNAPL, but had difficulty in three very heterogeneous regions with DNAPL pools. Site soil is composed of fine silty sand with clay lenses, with hydraulic conductivity ranging from 10{sup {minus}5} to 10{sup {minus}4} cm/sec. At 18 feet a dense silty clay till or groundmoraine forms an aquitard with a hydraulic conductivity of less than 10{sup {minus}8} cm/sec. Complicating site remediation efforts, the shallow groundwater table is encountered at 7 feet below grade. SPH is an in-situ thermal remediation technology, which uses in- situ soil and groundwater heating to remediate the subsurface. Most of the remaining DNAPL at the site was located beneath a large brick building. To access the DNAPL, soil heating electrodes were installed directly through the building floor. A 106-electrode network was installed to remediate the TCE and TCA which existed as DNAPL pools on top of a clay aquifer at 18 feet below grade. The electrodes were designed perform electrical heating throughout a depth interval of 11--21 feet below grade, to boil the groundwater and DNAPL in the interval from 5-24 feet. The chlorinated solvents were removed in the vapor phase through venting slots installed in the electrodes. The slots were positioned above the water table within a region consisting of structural fill with moderate permeability. This paper represents the final results of the remediation, and discuss the economics of Six-Phase Heating for DNAPL remediation.
- Research Organization:
- Current Environmental Solutions (US)
- OSTI ID:
- 20003337
- Report Number(s):
- CONF-990608--
- Country of Publication:
- United States
- Language:
- English
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