A full-scale demonstration of in situ chemical oxidation through recirculation at the X-701B site

Abstract

This report has been reproduced directly from the best availattie copy.Available to DOE and DOE contractors . . ( H 2 0 2 ) , if applied at sufficient loadings to contaminated soils, can effectively oxidize trichloroethylene (TCE) and perchloroethylene (PGE). Between the two oxidants, KMn04 is more stable and may result in a higher rate of TCE degradation. LIST OF TABLESIn 1996, researchers at Oak Ridge National Laboratory ( O N ) proposed an oxidant delivery technique involving injection and recirculation of the oxidant solution into a contaminated aquifer through multiple horizontal and vertical wells. This technique would be applicable to saturated, hydraulically conductive formations. In the spring of 1997, the Department of Energy (DOE) at the Portsmouth Gaseous Diffusion Plant (PORTS) agreed to collaborate with the DOES Subsurface Contaminants Focus Area to conduct a field-scale treatability study using in situ chemical oxidation through recirculation (ISCOR). PORTS agreed to support the demonstration at the X-701B site where the technology can potentially be used to remediate TCE-contaminated groundwater and sediments. The ISCOR field demonstration took advantage of existing infrastructure and extensive site characterization data generated from previous field demonstrations at X-701B. The field test was implemented using a pair of previously installed horizontal wells that transect an area of DNAPL contamination. Groundwater was extracted from one horizontal well, pumped to an existing pump and treat facility, dosed with KMnO4, and re-injected into a parallel horizontal well approximately 90 ft away. The field demonstration lasted approximately one month. Treatment effectiveness was determined by comparing contaminant levels in pre-treatment, during, and post-treatment groundwater samples and preand post-treatment soil samples Analytical results from the field demonstration indicate that ISCOR is effective at oxidizing TCE in the saturated zone. Lateral and vertical heterogeneities within the Gallia impacted the ability to deliver oxidant solution uniformly throughout the area between the horizontal wells. Furthermore, TCE in the neighboring low-permeability formations (the Sunbury and Minford layers) was not affected by oxidant recirculation through the G a l l i a . The oxidant may not have had time to diffuse from the Gallia into the Sunbury or Minford formations given the short duration of this test. However, in general, TCE was not detected where oxidant was present in samples collected from Gallia monitoring wells within the test region. Reduction of the TCE mass within the more conductive Gallia formation will lead to an overall reduction of TCE mobility within the X-701B area. Long-term groundwater monitoring will be required to fully assess the impact of this demonstration on the ISCOR test region.. vi ACKNOWLEDGMENTSThe planning and execution of the full-scale demonstration required the efforts of many individuals. The contributions of the following are recognized and appreciated.

In Situ Chemical Oxidation Through Lance Permeation at the Portsmouth Gaseous Diffusion Plant (PORTS)

“…2b for location) was measured at 87 ppb, a significant drop from historical TCE concentrations that ranged from 1000 to 10000 ppb. This decrease may be a direct result of the ISCO-LP treatment and/or previous ISCO field demonstrations conducted upstream of this well (West et al 1998). TCE concentrations in the other three wells sampled after the field test were not significantly different from pretreatment levels.…”

Permanganate Treatment of DNAPLs in Reactive Barriers and Source Zone Flooding Schemes - Final Report

“…The flow from the horizontal injection well to the Gallia was not uniformly distributed along the wellbore. As noted by West et al (1997) and Korte et al (1997), aquifer heterogeneity near the well, clogging of the well, or a pressure drop along the well screen may have contributed the variable flooding of the zone between the wells. Without additional data, we could not determine the exact cause of this pattern of flooding.…”

“…reported the results of laboratory and controlled field experiments using KMnO 4 to remediate trichloroethylene and perchloroethylene. West et al (1997) undertook a field demonstration of the in situ scheme for source-zone remediation at a DOE facility. Schwartz (1998, 1999) examined the kinetic behavior of chlorinated ethylenes in reactions with MnO 4 -.…”

Permanganate Treatment of DNAPLs in Reactive Barriers and Source Zone Flooding Schemes

“…flooding at a DOE facility (West et al, 1997). A field-scale experiment of MnO4-oxidation of TCE was performed at the Department of Energy Portsmouth Gaseous Diffusion Plant (PORTS) in Ohio by researchers from Oak Ridge National Laboratory (ORNL) (West et al, 1997).…”

“…A field-scale experiment of MnO4-oxidation of TCE was performed at the Department of Energy Portsmouth Gaseous Diffusion Plant (PORTS) in Ohio by researchers from Oak Ridge National Laboratory (ORNL) (West et al, 1997). Readers can refer to West et al (1997) for details of the physical setting and actual test. A two-dimensional model of 51x51 nodes was constructed to represent the treatment zone and its vicinity.…”