Dense Nonaqueous Phase Liquids (DNAPLs)

In Situ Reduction

Chlorinated Solvents in the Class of Halogenated Alkenes

Case Studies: Chlorinated Solvent Mixtures

Cost and Performance Report: Nanoscale Zero-Valent Iron Technologies for Source Remediation
A. Gavaskar, L. Tatar, and W. Condit.
Naval Facilities Engineering Service Center, Port Hueneme, CA. CR-05-007-ENV, 54 pp, 2005

This cost and performance report is the result of a comparative evaluation of the performance of zero-valent iron injection at three Navy sites: Hunters Point Shipyard (micron-scale particles), and Naval Air Station Jacksonville and Naval Air Engineering Station Lakehurst (nanoscale particles).

Enhanced In Situ Reduction of cVOCs using Zero-Valent Iron
E. Corack, S. MacEwen, J. Liskowitz, M. Liskowitz, P. Tully, and D. Steckler.
Fifth International Conference on Remediation of Chlorinated and Recalcitrant Compounds, Monterey, CA, 2006

• Abstract
• Poster 1
• Poster 2

In early 2005, ARS completed a full-scale Ferox(sm) project at Site 13 of the former Naval Surface Warfare Center White Oak in Silver Spring, MD. The primary goal of this remedial action was source zone reduction of 1,1,2,2-PCA, cis-1,2-DCE, PCE, and TCE. As part of the injection process, pneumatic fracturing was applied as a precursor to emplacing the ZVI slurry.

Explanation of Significant Differences, Areas I And J Ground Water, Naval Air Engineering Station, Lakehurst, NJ
U.S. EPA, 12 pp, Sep 2003

The Navy proposes to use nanoscale particles in lieu of cometabolism to reduce the higher levels of groundwater contamination and expedite the achievement of overall cleanup goals for chlorinated VOCs in Areas I and J. Laboratory bench-scale testing and field testing of bimetallic nanoscale particle (BNP) technology was conducted in April 2001 and February 2002, respectively. BNP use involved the injection of submicron particles of ZVI with a trace coating of a noble catalyst. Because nanoscale particle technology is innovative, the technology has evolved since the tests took place. An advanced version of nanoscale particles has been developed that uses porous iron but does not require the use of a noble catalyst. The Navy is considering whether to use BNP or porous iron based on cost/availability.

Field Assessment of Carboxymethyl Cellulose Stabilized Iron Nanoparticles for In Situ Destruction of Chlorinated Solvents in Source Zones
He, F., D. Zhao, and C. Paul.
Water Research 44(7):2360-2370(2010)

CMC-stabilized ZVI nanoparticles (with trace Pd catalyst) were pilot tested for in situ destruction of CVOCs (PCE, TCE, and PCBs) that had been in groundwater for decades. The pilot site was located in a well-characterized secondary source zone of PCBs and CVOCs. The stabilized nanoparticle suspension was prepared on site. Rapid degradation of PCE and TCE was observed in both downgradient monitoring wells following each injection. Although CVOC concentrations gradually returned to their pre-injection levels after ~2 weeks, the injection of CMC-stabilized nanoparticles and the abiotic reductive dechlorination process appeared to boost subsequent long-term bio-dechlorination as PCE and TCE concentrations continued to decline after 2 weeks. Longer abstract Additional information: Field Report (2006), EPA Grant GR832373, Slide Presentation (2011)

Field Testing of Bimetallic Nanoscale Particle Technology for In-Situ Groundwater Treatment of a Fractured Rock DNAPL Zone
W. Zhang, L. Walata, R. Nash, F. Gheorghiu, R. Glazier, and R. Venkatakrishnan.
Geophysical Research Abstracts, Vol 5, Abstract 10432, 2003

In Situ Bimetallic Nanoscale Particle (BNP) Treatment at the Naval Air Engineering Station Site (Area I), Lakehurst, New Jersey (2002)
Federal Remediation Technologies Roundtable Cost and Performance Case Study.

In situ BNP treatment, which is categorized as in situ chemical reduction, consists of submicron particles of ZVI with a trace coating of palladium that acts as a catalyst; treatment of contaminants is based on a redox process where the ZVI serves as the electron donor. A pilot test of in situ BNP was conducted at the site from February to March 2002 to assess its effect on groundwater contaminated with chlorinated hydrocarbons, including PCE, TCE, 1,1,1-TCA, and vinyl chloride. Between February 8 to May 6, 2002, the total reduction of VOCs within the treatment area was ~74%.

Nanoscale Iron Particles for Environmental Remediation: An Overview
W.-X. Zhang.
Journal of Nanoparticle Research, Vol 5, p 323-332, 2003

The author discusses recent nanoscale iron developments in both laboratory and field studies, including a field-scale treatability pilot test to remediate chlorinated VOCs (PCE, TCE, DCE) that was carried out at an industrial/research facility located in Research Triangle Park, NC.

Permeable Reactive Barrier Downgradient of the Southern Source Area, Former Tecumseh Products Company Site, Tecumseh, Michigan: Construction Documentation Report
U.S. EPA Region 5, 148 pp, 2012

The PRB was installed in May 2011. Site COCs include chlorinated VOCs (mainly TCE, TCA, and daughter products), SVOCs, 1,4-dioxane, metals, cyanide, and PCBs. Where the target treatment zone is relatively shallow, the design called for in situ soil blending to deliver DARAMEND(r) (a pelletized form of controlled-release carbon and ZVI) to the subsurface. The design included the use of injections to deliver ABC(r)+ (a patented mixture of ethyl lactate and glycerin, plus ZVI) to portions of the PRB farther beneath ground surface. ABC(r)+ also was used for shallow injections around an existing sewer pipe. Additional resources: Tecumseh website .

Case Studies: PCE

DNAPL Remediation at Camp Lejeune Using ZVI-Clay Soil Mixing
C. Bozzini, T. Simpkin, T. Sale, D. Hood, and B. Lowder.
The Fifth International Conference Remediation of Chlorinated and Recalcitrant Compounds, 22-25 May 2006, Monterey, California.

Soil mixing with ZVI/clay addition was implemented at the site in a 17-day period in February 2005. The ZVI treated the chlorinated solvents (primarily PCE), while the clay created a low permeability zone that limited flow of groundwater into and out of the treated area. A crane was used to turn a 10-ft auger while injecting the ZVI/clay slurry. A total of 200 tons of ZVI and 100 tons of bentonite was mixed to create 146 overlapping columns. Off-gas was treated with activated carbon. After allowing six weeks for settlement, 196 tons of cement were added to the top 5 feet of soil over the treatment area to stabilize the site for a parking lot. One year after treatment, PCE soil concentrations had decreased significantly, with concentrations over the entire treatment area averaging an 82% decrease and a median concentration reduction of 99%. Reductions were lower (61%) in about one-fifth of the area where mobile DNAPL had been present prior to treatment but 99% in the remaining treated area. ZVI was still present in the treatment area, so continued treatment should occur. Groundwater concentrations of PCE were reduced by > 96% in the treatment area, but DCE concentrations did increase significantly in one groundwater well. Downgradient water quality improved after treatment, with PCE reduction of 67 and 90%. Hydraulic conductivity within the treatment area decreased 50 to 400 times (one to two orders of magnitude) with a post-treatment hydraulic conductivity of 0.013 ft/day, so there should be a significant reduction in mass flux from the treated area. Additional information: Olson et al., Chlorinated Solvent Source-Zone Remediation via ZVI-Clay Soil Mixing: 1-Year Results (Abstract). Ground Water Monitoring & Remediation 32(3):63-74(2012); Technology summary

Emulsified Zero-Valent Nano-Scale Iron Treatment of Chlorinated Solvent DNAPL Source Areas
T. Krug, S. O'Hara, M. Watling, and J. Quinn.
ESTCP Project ER-0431, 763 pp, 2010

A field demonstration/validation of EZVI injections to remediate chlorinated solvent DNAPL (PCE and daughter products) source zones was conducted in 2006 at Site 45, a former drycleaning facility at Marine Corps Recruit Depot, Parris Island, SC. EZVI promotes both abiotic and biotic degradation of contaminants. The demonstration also compared the efficacy of pneumatic injection versus direct injection for EZVI delivery. ESTCP Cost & Performance Report

Remediation of a Former Dry Cleaner Using Nanoscale Zero Valent Iron
Jordan, M., N. Shetty, M.J. Zenker, and C. Brownfield.
Remediation Journal 24(1):31-48(2013)

Beneath a former dry cleaner located in Chapel Hill , NC , PCE was observed in site soil at concentrations up to 2,700 mg/kg and in shallow groundwater at concentrations up to 41 mg/L. NZVI was injected as an interim measure to treat the PCE source area. To achieve a design loading rate of 0.001 kg of iron per kg of aquifer material, ~725 kg of NanoFe(tm) was injected over a 2-week period into a saprolite and partially weathered rock aquifer. The injections resulted in near elimination of PCE within one month, while cis-1,2-DCE accumulated at high concentrations (>65 mg/L) for 12 months. Mass reduction of PCE and total ethenes was estimated at 96% and 58%, respectively, compared to baseline conditions. Detections of ethene confirmed complete dechlorination of PCE. Based on hydrogen gas generation, NZVI reactivity lasted 15 months. This paper is Open Access at the Remediation Journal website.

TCE

Comparison of EHC, EOS, and Solid Potassium Permanganate Pilot Studies for Reducing Residual TCE Contaminant Mass
Marks, C.
E2S2: Environment, Energy Security and Sustainability Symposium and Exhibition, 9-12 May 2011, New Orleans, Louisiana. Presentation 12621, 30 slides, 2011

At the Defense Distribution Depot San Joaquin-Sharpe (DDJC-Sharpe) site, Lathrop, CA, three treatment technologies were evaluated for their potential to increase TCE mass removal in the saturated zone. Introduction of emulsified oil (EOS) in the North Balloon began in April 2008, injection of solid potassium permanganate in the South Balloon began in May 2008, and injection of a redox compound (EHC, complex organic carbon plus ZVI) in the Central Area began in August 2008. Where the amendment was able to contact the contaminant, all three amendments reduced TCE concentrations to <5 ug/L (the cleanup level). All three amendments continued to distribute/diffuse horizontally after injection and had secondary water quality impacts. Solid potassium permanganate was selected as the preferred amendment because it distributed/diffused significantly more in fine-grained soils than the other two amendments, destroyed TCE more quickly without formation of daughter products, and was cost effective because multiple injections were not necessary. The pilot study results also showed that hydraulic fracturing increased the distribution of the amendment in fine-grained soils when compared to gravity-fed injection wells. Additional information: Longer Abstract; DDJC-Sharpe 2009 5-Year Review

Field Demonstration of DNAPL Dehalogenation Using Emulsified Zero-Valent Iron
J. Quinn, C. Geiger, C. Clausen, K. Brooks, C Coon, W.-S. Yoon, A. Gavaskar, T. Holdsworth, S. O'Hara,T. Krug, and D. Major.
Environmental Science & Technology, Vol 39, p 1309-1318, 2005

Innovative Injection Technique to Treat DNAPL in Granular and Fine Grained Matrices
Noland, S., R. Boyle, and T.A. Harp.
The Eighth International Conference for Remediation of Chlorinated and Recalcitrant Compounds, Monterey, CA, May 21-24, 2012. Battelle Press, Columbus, OH. 8 pp, 2012

High-energy, low-volume pulses of a water-based suspension of BOS 100^®, a granular activated carbon impregnated with metallic iron, were employed to remediate DNAPL at a large urban industrial facility, with injections facilitated using conventional hydraulic fracturing. Although large portions of the dissolved-phase plume responded to this technique, some areas were resistant, suggesting input from unknown sources. High-resolution sampling indicated the presence of localized thin seams of DNAPL-impacted soils at several locations in the vicinity of the former TCE underground storage tank. A modified "jetting" approach was developed that allowed extremely accurate placement and injectant/soil mixing over a relatively thick zone.

In Situ Chemical Reduction at the Marshall Space Flight Center, Source Area 2, Huntsville, Alabama (2003)
Federal Remediation Technologies Roundtable Cost and Performance Case Study.

A pilot test of in situ chemical reduction technology was performed to assess the ability of the technology to treat dissolved-phase TCE in the residuum groundwater beneath a source area. A ZVI slurry (the Ferox[sm] process) was emplaced into the source area via pneumatic fracturing.

Jet-Assisted Injection of Nano-Scale, Zero-Valent Iron to Treat TCE in a Deep Alluvial Aquifer
Chang, P.R., A.D. Pantaleoni, and D.J. Shenk.
Proceedings of the Seventh International Conference on Remediation of Chlorinated and Recalcitrant Compounds (Monterey, CA; May 2010). Battelle Press, ISBN: 978-0-9819730-2-9, Paper & presentation D-098, 6 pp & 15 slides, 2010

An innovative injection approach was field-tested at a former aerospace manufacturing facility (Unidynamics, Goodyear, Arizona) to overcome significant challenges posed by the low permeability of the soil and depth of the contaminated groundwater. A 10,000-pound psi fracture lance injection tool was used to distribute nano-scale ZVI in a targeted injection interval between 108 to 118 ft bgs. Injection of 1,400 pounds of PolyMetallix(tm) was completed at two injection points spaced 15 ft apart over 3 days. Each injection point had a radius of 30 ft. Groundwater data showed a TCE mass removal efficiency of 82 to 96% within 2 weeks after completion of the injections.

Reductive Dehalogenation of DNAPLs Using Emulsified Zero-Valent Iron
S. O'Hara, T. Krug, D. Major, E. Hood, J. Quinn, C. Clausen, C. Geiger, and D. Reinhart.
Remediation of Chlorinated and Recalcitrant Compounds Conference, Monterey, California, 2002. Battelle Press, Columbus, OH. Poster presentation, 2002

The Use of Zero-Valent Iron Injection to Remediate Groundwater: Results of a Pilot Test at Marshall Space Flight Center
B. McElroy, A. Keith, J. Glasgow, and S. Dasappa.
Remediation Journal, Vol 13 No 2, p 145-153, 2003

During July and August 2000, an in situ chemical reduction field pilot test was implemented of ZVI powder in slurry form, using the Ferox(sm) process patented by ARS Technologies, Inc. The pilot test focused on TCE-contaminated groundwater within the rubble zone. Maximum pre-injection concentrations of about 72,800 µg/L were observed. The potential presence of unexploded ordnance forced an implementation strategy where source area injections were completed, as feasible, followed by overlapping injections in a downgradient alignment to create a permeable reactive zone for groundwater migration.