The remediation methods designed and deployed for use at the Department of Energy Savannah River Site 321-M solvent storage tank area (SSTA) comprise a complete set of cleanup and control techniques using steam remediation and electrical resistance tomography. The technologies include the engineered combination of steam injection; dual-phase extraction for subsurface remediation; and an in-situ tomographic imaging technology for monitoring of thermal treatment zones in the subsurface. The technologies use methods developed for enhanced oil recovery using steam injection.
At the SSTA, the remediation zone was 31 × 31 m (100 × 100 ft) on the surface and extended from 6- to 49-m (20- to 160-ft) depth. The ambient water table exists at approximately 44-m (145-ft) depth. Steam injection wells ringed the target zone, with multiphase extraction dominated by a centered dual-phase extraction well, with three additional existing perimeter vapor extraction wells.
The SSTA field-scale deployment of steam injection, groundwater pumping, and vapor extraction removed 31,000 kg (68,000 lb) of volatile organic compounds during 12 months of operation. Total steam injected for the 12-month period of operations was approximately 48 × 109 kJ (45 × 109 BTU), injected at wellhead pressures between 0.15 and 0.38 MPa (7 and 40 psig), depending on lithology of the screened interval, depth, and operational considerations.