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Stroo H.F.,Sunset Inc. | Leeson A.,Strategic Environmental Research and Development Program | Marqusee J.A.,Strategic Environmental Research and Development Program | Johnson P.C.,Arizona State University | And 7 more authors.
Environmental Science and Technology | Year: 2012

The past decade has seen rapid progress in source zone remediation, and an increasing understanding of the capabilities and limitations of potential technologies. Research has produced a large database from well-monitored demonstrations, more effective models to improve decision-making, and a better understanding of the physical, chemical, and biological constraints to achieving complete restoration. This experience has led to technology selection guidance to help managers develop reasonable expectations for treatment.133 It also has led to several publications from researchers funded through SERDP and ESTCP on source zone treatment (including technology-specific cost and performance reports), available at http://www.serdp-estcp.org/Featured-Initiatives/Cleanup- Initiatives/DNAPL-Source-Zones. Experience also has shown that different technologies are needed for different times and locations, and that deliberately combining technologies may improve overall remedy performance. Guidance on adaptive management and integrated strategies for DNAPL sites has been developed to help practitioners select the best combinations and develop realistic objectives. 52,134 Such guidance should improve source treatment and save money, through more cost-efficient characterization and monitoring, more efficient and appropriate uses of remedial technologies, and greater consensus on source treatment decisions. Challenges remain, however, particularly at complex sites that are difficult to characterize and where prolonged treatment and/or multiple technologies have failed to achieve remedial goals. Many DNAPL sites still cannot be restored to regulatory criteria within a few years or within a "reasonable time frame" (often considered roughly 30 years), and therefore will require long-term management.


Su C.,U.S. Environmental Protection Agency | Puls R.W.,U.S. Environmental Protection Agency | Puls R.W.,University of Oklahoma | Krug T.A.,Geosyntec Consultants | And 4 more authors.
Water Research | Year: 2013

Nanoscale zerovalent iron (NZVI) such as Toda Kogyo RNIP-10DS has been used for site remediation, yet information is lacking regarding how far injected NZVI can travel, how long it lasts, and how it transforms to other minerals in a groundwater system. Previously we reported effective mass destruction of chlorinated ethenes dominated by tetrachloroethene (PCE) using emulsified zerovalent iron (EZVI) nanoparticles of RNIP-10DS in a shallow aquifer (1-6m below ground surface, BGS) at Site 45, Marine Corps Recruit Depot, Parris Island, South Carolina, USA. Here we report test results on transport and transformation of injected EZVI in the subsurface. We employed two EZVI delivery methods: pneumatic injection and direct injection. Effective delivery of EZVI to the targeted zone was achieved with pneumatic injection showing a travel distance from injection points of up to 2.1m and direct injection showing a travel distance up to 0.89m. X-ray diffraction and scanning electron microscopy studies on particles harvested from well purge waters indicated that injected black colored NZVI (α-Fe0) was transformed largely to black colored cube-like and plate-like magnetites (Fe3O4, 0.1-1μm, 0-9 months), then to orange colored irregularly shaped lepidocrocite (γ-FeOOH, 0.1-1μm, 9 months to 2.5 years), then to yellowish lath-like goethite (α-FeOOH, 2-5μm, 2.5 years) and ferrihydrite-like spherical particles (0.05-0.1μm) in the top portion of the aquifer (1-2m BGS). No α-Fe0 was found in most monitoring wells three months after injection. The formed iron oxides appeared to have a wider range of particle size (submicron to 5μm) than the pristine NZVI (35-140nm). Injected NZVI was largely transformed to magnetite (0.1-1μm) during two and half years in the lower portion of the aquifer (3-6m). © 2013.


Salter-Blanc A.J.,Oregon Health And Science University | Suchomel E.J.,Geosyntec Consultants | Fortuna J.H.,Klohn Crippen Berger Ltd. | Nurmi J.T.,Clackamas Community College | And 6 more authors.
Ground Water Monitoring and Remediation | Year: 2012

The efficacy and feasibility of using zerovalent zinc (ZVZ) to treat 1,2,3-trichloropropane (TCP)-contaminated groundwater was assessed in laboratory and field experiments. In the first portion of the study, the reactivity of commercially available granular ZVZ toward TCP was measured in bench-scale batch-reactor and column experiments. These results were used to design columns for on-site pilot-scale treatment of contaminated groundwater at a site in Southern California. Two of the ZVZ materials tested were found to produce relatively high rates of TCP degradation as well as predictable behavior when scaling from bench-scale to field testing. In addition, there was little decrease in the rates of TCP degradation over the duration of field testing. Finally, no secondary impacts to water quality were identified. The results suggest that ZVZ may be an effective and feasible material for use in engineered treatment systems, perhaps including permeable reactive barriers. Ground Water Monitoring & Remediation. © 2012, National Ground Water Association.


Su C.,U.S. Environmental Protection Agency | Puls R.W.,U.S. Environmental Protection Agency | Puls R.W.,University of Oklahoma | Krug T.A.,Geosyntec Consultants | And 4 more authors.
Water Research | Year: 2012

A field test of emulsified zero valent iron (EZVI) nanoparticles was conducted at Parris Island, SC, USA and was monitored for two and half years to assess the treatment of subsurface-source zone chlorinated volatile organic compounds (CVOCs) dominated by tetrachloroethene (PCE) and its chlorinated daughter products. Two EZVI delivery methods were used: pneumatic injection and direct injection. In the pneumatic injection plot, 2180 L of EZVI containing 225 kg of iron (Toda RNIP-10DS), 856 kg of corn oil, and 22.5 kg of surfactant were injected to remedy an estimated 38 kg of CVOCs. In the direct injection plot, 572 L of EZVI were injected to treat an estimated 0.155 kg of CVOCs. After injection of the EZVI, significant reductions in PCE and trichloroethene (TCE) concentrations were observed in downgradient wells with corresponding increases in degradation products including significant increases in ethene. In the pneumatic injection plot, there were significant reductions in the downgradient groundwater mass flux values for PCE (>85%) and TCE (>85%) and a significant increase in the mass flux of ethene. There were significant reductions in total CVOC mass (86%); an estimated reduction of 63% in the sorbed and dissolved phases and 93% reduction in the PCE DNAPL mass. There are uncertainties in these estimates because DNAPL may have been mobilized during and after injection. Following injection, significant increases in dissolved sulfide, volatile fatty acids (VFA), and total organic carbon (TOC) were observed. In contrast, dissolved sulfate and pH decreased in many wells. The apparent effective remediation seems to have been accomplished by direct abiotic dechlorination by nanoiron followed by biological reductive dechlorination stimulated by the corn oil in the emulsion. © 2012 .

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