Modified Ferrous Ion Activated Persulfate Oxidation for In Situ Remediation of Trichloroethylene
Chenju Liang, National Chung-Hsing University, Taichung, Taiwan
Clifford J. Bruell, University of Massachusetts Lowell, Lowell, MA
Michael C. Marley, Xpert Design Diganostics, LLC., Stratham, NH
Kenneth L. Sperry, Xpert Design Diagnostics, LLC., Allentown, PA  

Chemical Oxidation Using Ozone, Hydrogen Peroxide, and Air Injection Systems for BTEX, MTBE, and TBA
Charles B. Whisman, Groundwater & Environmental Services, Inc.,  Exton, PA  

The Application of In-situ Chemical Oxidation for Treatment of Chlorinated Solvents in Naturally Reducing Environments
Steven A. Dielman, ENVIRON International Corporation, Arlington, VA
Randall F. Martel, ENVIRON International Corporation, Arlington, VA
Ned Bolth, ENVIRON International Corporation, Arlington, VA

ISCO Technology Overview – Do You Really Understand the Chemistry
Ian T. Osgerby, USACE NewEngland District, Concord, MA

Rapid Controlled Oxidation and Biologic Enhancement of Petroleum Contaminants in Clayey, Silty, and Sandy Soils
Thomas D. Douglas, P.E., AET, LLC, Pensacola, FL
Ian T. Osgerby, Ph. D., P.E., US Army Corp of Engineers, Concord, MA
Thomas A. Reed, DeepEarth Technologies, Inc., Avarda, CO 

CVOC Source Identification through In Situ Chemical Oxidation in Fractured Bedrock
Mark D. Kauffman, ENSR International, Westford, MA

Modified Ferrous Ion Activated Persulfate Oxidation for In Situ Remediation of Trichloroethylene

Chenju Liang, Dept. of Environmental Eng., National Chung-Hsing University, Taiwan, 250 Kuo Kuang Road, Taichung, Taiwan, Email: Chenju.Liang@gmail.com
Clifford J. Bruell, Dept. of Civil & Environmental Eng., University of Massachusetts Lowell, One University Ave., Lowell, MA 01854, Tel: 978-934-2284, Fax: 978-934-3052, Email: Clifford_Bruell@uml.edu
Michael C. Marley, Xpert Design Diganostics, LLC, 22 Marin Way, Stratham, NH 03885, Tel: 603-778-1100, Fax: 603-431-7807, Email: Marley@xdd-llc.com
Kenneth L. Sperry, Xpert Design Diagnostics, LLC, 1275 Glenlivet Drive, Suite 100, Allentown, PA 18106, Tel: 484-224-3031, Fax: 484-224-2999, Email: Sperry@xdd-llc.com

It has been postulated that the persulfate anion (S₂O₈^2-) can be thermally or chemically activated to produce a powerful oxidant known as the sulfate free radical (SO₄^-·) with a standard redox potential of 2.6V, which is capable of destroying groundwater contaminants such as trichloroethylene (TCE).  The objective of the laboratory study is to examine the capability of ferrous ion (Fe²⁺) activated persulfate oxidation of TCE in both aqueous and soil slurry phases.  Experiments using various molar ratios of persulfate/Fe²⁺/TCE in an aqueous system indicate that TCE degradation occurred almost instantaneously and then the reaction stalled far from completion.  Sequential addition of Fe²⁺ resulted in an increased TCE removal efficiency.  Therefore, it appeared that Fe²⁺ played an important role in generating SO₄^-·.  Either cannibalization of SO₄^-· in the presence of Fe²⁺ or the rapid conversion of all ferrous ions to ferric ions limited the ultimate oxidizing capability of the system.  An observation of oxidation-reduction potential variations revealed that the use of Fe²⁺ activated persulfate-thiosulfate redox couple could significantly decrease the strong oxidizing conditions and result in an improvement of TCE removal.  In addition, a chelating agent was used in attempt to manipulate the quantity of Fe²⁺ in solution.  A comparison of chelating agents was initially conducted.  The use of chelated Fe²⁺ resulted in the maintenance of the Fe²⁺ in solution and promoted more efficient destruction of TCE.

Chemical Oxidation Using Ozone, Hydrogen Peroxide, and Air Injection Systems for BTEX, MTBE, and TBA

Charles B. Whisman, Director of Engineering, Groundwater & Environmental Services, Inc.,  410 Eagleview Boulevard, Suite 110, Exton, PA, 19341, Tel: 610-458-1077 ext. 156, Fax: 610-458-2300, Email: cwhisman@gesonline.com

There can be many challenges with providing cost-effective and aggressive remediation solutions to sites impacted with BTEX, MTBE, and TBA compounds.  Groundwater & Environmental Services, Inc. has developed and utilized various innovative ozone, hydrogen peroxide, and air injection systems, which can remediate BTEX, MTBE, and TBA impact at costs significantly below conventional methods and within a relative short time frame.  Case studies will be presented where BTEX, MTBE, and TBA impact in soil and groundwater was remediated through the combination of ozone and hydrogen peroxide injection or through the combination of hydrogen peroxide and air.  The two technologies which will be presented will detail various case studies where contaminated soil and groundwater was aggressively remediated through monthly and short-term (daily/weekly) remediation solutions.  Case studies will be presented where short-term mobile hydrogen peroxide and air injection systems were utilized to remediate soil and groundwater impacted with BTEX and MTBE at relatively low life-cycle remediation costs ($15,000 to $200,000).

The case studies to be presented are from sites exhibiting varying lithologies and within different regulatory environments.  The presentation will include a discussion on evaluating life-cycle costs for chemical oxidation and other remediation technologies.  The discussion will also evaluate various methods available to perform on-site feasibility tests and off-site bench tests which can be utilized to evaluate the potential effectiveness of in-situ chemical oxidation using ozone and hydrogen peroxide injection or hydrogen peroxide and air injection systems.

The Application of In-situ Chemical Oxidation for Treatment of Chlorinated Solvents in Naturally Reducing Environments

Steven A. Dielman, P.E., P.G., ENVIRON International Corporation, 4350 North Fairfax Drive, Suite 300, Arlington, VA 22203, Tel: 703-516-2363, Fax: 703-516-2344, Email: sdielman@environcorp.com
Randall F. Martel, ENVIRON International Corporation, 4350 North Fairfax Drive, Suite 300, Arlington, VA 22203, Tel: 703-516-2430, Fax: 703-516-2344, Email: rmartel@environcorp.com
Ned Bolth, ENVIRON International Corporation, 4350 North Fairfax Drive, Suite 300, Arlington, VA 22203, Tel: 703-516-2394, Fax: 703-516-2344, Email:nbolth@environcorp.com

In naturally reducing subsurface environments, many common chlorinated solvents (CSs) can undergo biodegradation by indigenous microorganisms capable of halorespiration.  This process often limits the ultimate extent of dissolved CS plumes in ground water and may be relied upon in part or whole as a site remediation strategy.   A common regulatory criterion for approval of such “natural attenuation” or “intrinsic biodegradation” strategies is source control for unsaturated and saturated soils in areas where CSs were released to the subsurface.  In such areas, CSs, often in the form of dense non-aqueous phase liquids (DNAPL), would otherwise undergo slow leaching and/or dissolution into ground water, thereby acting as long-term sources of CS plumes.  

A technology that is increasingly being used for CS source control is in-situ chemical oxidation (ISCO) by permanganate or other solutions.  An effective ISCO program for CS source areas has the potential, however, to disrupt the halorespiration of dissolved CSs, which requires reducing conditions.  This presentation describes the results of a potassium permanganate (KMnO₄) ISCO source control program at a site characterized by the presence of tetrachloroethylene (PCE) DNAPL beneath an operating facility.   A ground water plume of tetrachloroethylene (PCE) and its degradation by products trichloroethylene (TCE), cis-1,2-dichloroethylene (1,2-DCE) and vinyl chloride exists downgradient of the source area, but is undergoing highly effective halorespiration facilitated by naturally reducing conditions.  This presentation focuses on the design considerations necessary for an effective ISCO application in a reducing environment and discusses the results of a monitoring program that was specifically designed to both: (1) evaluate the effectiveness of KMnO₄ ISCO source control for saturated soils containing DNAPL, and (2) evaluate the effects of ISCO on subsurface geochemical conditions previously conducive to on-going effective biodegradation by halorespirating microorganisms.

ISCO Technology Overview - Do you really Understand the Chemistry? 

Ian T. Osgerby, PhD, PE; USACE/CENAE New England District, Concord MA. USACE,  696 Virginia Road, Concord,  MA  01742, Tel: 978 318 8631, Fax: 978 318 8663, Email:
ian.t.osgerby@usace.army.mil

The reaction chemistry of ISCO is presented for the common oxidant systems employed in ISCO:  catalyzed peroxide propagations (Modified Fenton's), permanganate, ozone/ozone-peroxide (peroxone), and persulfate.  All of these oxidant systems, with the exception of permanganate are described by reaction schemes employing free radical generation, and all are dependant to some degree on local conditions such as water chemistry and pH.  A less familiar reactant condition may be the influence of inorganic and organic compounds in the soil matrix, which can have a strong influence over the intended outcome of the ISCO application.  Thus, naturally occurring organic compounds may overwhelm the contaminant demand for oxidant or prevent the transition of the adsorbed contaminant to the aqueous phase where ISCO reactions occur.  Naturally occurring inorganic compounds may actually cause destruction of the oxidant or modify the catalytic component.  Some experience with soils having markedly different matrix properties will be discussed to provide an illustration of some of the difficulties which may be faced in the practice of ISCO.  

Rapid Controlled Oxidation and Biologic Enhancement of Petroleum Contaminants in Clayey, Silty, and Sandy Soils

Thomas D. Douglas, P.E., AET, LLC, 9160 Roe Street, Pensacola, Florida 32514, Tel: 850-471-2127, Fax: 850-471-0750, Email: tdouglas@aetllc.com
Ian T. Osgerby, Ph. D., P.E., US Army Corp of Engineers, 696 Virginia Road, Concord, Ma, 01742, Tel: 978-318-8631, Fax:     978 -318 8663, Email: ian.t.osgerby@usace.army.mil
Thomas A. Reed, DeepEarth Technologies, Inc., 9530 West 54^th Place, Suite 100, Avarda, CO  80002, Tel: 303-456-8089, Fax: 303-356-5212, Email: tech@deepearthtech.com 

Clean up of petroleum in clay or low yielding soils is often difficult, problematic, expensive, or impractical; however, a controlled in-situ chemical oxidation process “CISCOP™” has been successfully used at several sites in northern Florida where soil with high clay content, carbonates, high organic content, and/or silty soil are present.  Recent treatments have demonstrated that petroleum mass is rapidly reduced in both soil and groundwater, with significant and substantial biologic enhancement demonstrated.  This process has been used adjacent to active tank pits and pump islands and where free phased product is present, with low risk.  The process uses metallic peroxides and hydrogen peroxide to oxidize contaminants to molecules that are used as a food by native bacteria following injections or over-spraying of CISCOP™ reagents.   Petroleum reducing bacteria counts indicate that bacteria are flourishing in soil and groundwater.  The pH of soil and water is buffered; therefore, bacterial reduction of contaminants can be sustained.  The combination of chemical oxidation and sustained biologic activity have resulted in the reduction of petroleum contaminants in soil and water of >80% in the vadose, smear, and saturated zones.  This process is being applied to the remediation of soils and water both in-situ and following excavations and at petroleum stations, even where free phased product is present, with good results.  This paper presents data which substantiates that significant petroleum mass reduction and enhanced biologic activity are occurring at sites where CISCOP™ treatments have been performed, even in clayey and silty soils where high carbonate concentrations are present.

CVOC Source Identification Through In-Situ Chemical Oxidation in Fractured Bedrock

Mark D. Kauffman, P.E., and James H. Vernon, Ph.D., P.G., ENSR International, Westford, MA

An in-situ chemical oxidation (ISCO) pilot program, using Fenton’s Reagent (hydrogen peroxide and a ferrous sulfate catalyst), was performed to assess its effectiveness in destroying chlorinated volatile organic compounds (CVOCs) in a fractured-bedrock aquifer.  This case study is unique because it was one of the first applications of ISCO in fractured bedrock.  In addition, the targeted CVOC reduction from 1,500 to 100 micrograms per liter (μg/L) was relatively aggressive compared to most ISCO applications.  This pilot program also provided the opportunity for an independent, third party evaluation of ISCO in a fractured-bedrock environment.  The site geology consists of approximately 6 meters (m) of unconsolidated glacial deposits overlying fractured bedrock, with a groundwater depth of approximately 2 m.  Initial characterization activities, including injection testing and multi-level packer sampling, identified a pre-ISCO CVOC plume extending approximately 90 m long by 45 m wide and spanning a vertical depth between 3 and 35 m.  Packer sampling results indicated the pre-ISCO plume had an asymmetric configuration that was consistent with the injection-test results.  The ISCO pilot program involved the injection of 14,237 liters of 50% hydrogen peroxide, combined with a ferrous sulfate and pH-buffering catalyst.  Two injection events were performed, with overlapping performance sampling.  Samples collected 30 to 45 days after each injection event, showed CVOC concentrations below the treatment objective in many areas of the plume.  However, samples collected 60 to 100 days after each event, revealed significant rebound in most areas, at concentrations that approached initial pre-ISCO aquifer conditions.  An assessment of the results suggests that the injected oxidants primarily influenced the more transmissive fractures in the treatment zone, whereas the less transmissive fractures were less influenced.  Geochemical data and calculations indicate that the peroxide and catalyst may persist in the subsurface for prolonged periods (>200 days), thus complicating the assessment of rebound and the actual effectiveness of the technology.  Although the success of treatment was limited, it proved to be successful in enhancing the conceptual site model of the subsurface, better defining the applications and limitations of ISCO treatment in fractured bedrock, and most importantly, clearly identifying the source of residual CVOCs at the site.

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