Design and Performance Evaluation of Air Sparging Trench for the Treatment of VOCs and Arsenic
Omer J. Uppal, Xpert Design and Diagnostics, LLC, Stratham, NH

Electrochemical Generated Alkaline Barrier for In-situ Treatment of Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) Contaminated Groundwater
David B. Gent, US Army Engineer Research and Development Center, Vicksburg, MS

Chlorinated Soils Remediation Using Steam Injection Into Fractured Bedrock
Ian T. Osgerby, U.S. Army Corps of Engineers, New England, Concord, MA

Treatment of Trichloroethene with Reactive Nanoscale Iron Particles
Andreas D. Jazdanian, Toda America, Inc., Schaumburg, IL

Use of High Concentration Magnesium Sulfate Solution to Remediate Petroleum Impacted Groundwater
James F. Cuthbertson, Delta Environmental Consultants, Inc., Novi, MI

Completion of In-Situ Thermal Remediation of PAHs PCP and Dioxins at a Former Wood Treatment Facility
John Bierschenk, TerraTherm, Inc., Fitchburg, MA

How Low do you Want to Go?  In-Situ Thermal Desorption Consistently Achieves Low Cleanup Standards

Ralph S. Baker, TerraTherm, Inc., 356 Broad Street, Fitchburg, MA 01420, Tel: 978-343-0300, Fax: 978-343-2727, Email: rbaker@terratherm.com
Gorm Heron, TerraTherm, Inc., 28900 Indian Point, Keene, CA  93531, Tel. and Fax: (661) 823-1620, Email: gheron@terratherm.com
John C. LaChance, TerraTherm, Inc., 356 Broad Street, Fitchburg, MA 01420, Tel: 978-343-0300, Fax: 978-343-2727, Email: jlachance@terratherm.com
John M. Bierschenk, TerraTherm, Inc., 356 Broad Street, Fitchburg, MA 01420, Tel: 978-343-0300, Fax: 978-343-2727, Email: jbierschenk@terratherm.com

Establishing cleanup standards for contaminated source areas has long been a balance between what is considered technically feasible and what is mandated.  With respect to dense non-aqueous phase liquid (DNAPL) source zones in soil and groundwater, a school of thought has become prevalent that assumes that volatile and semivolatile organic compounds (VOCs and SVOCs) of concern cannot feasibly be treated in situ to concentrations low enough to be consistent with meeting Maximum Concentration Limits (MCLs) in groundwater.  This position has been most strongly held when it comes to DNAPL in challenging subsurface settings such as heterogeneous and fractured media. 

Now, as a result of over fifteen completed source area remediation projects using In-Situ Thermal Desorption (ISTD), which combines Thermal Conduction Heating (TCH) and vacuum extraction, a new paradigm for source treatment is emerging.  Because TCH takes advantage of the invariance of thermal conductivity across a wide range of soil types, no targeted area is left unheated.  ISTD therefore is able to accomplish complete and rapid treatment of DNAPL in lower-permeability and heterogeneous formations.  This presentation will review results from TCH projects treating both VOCs such as chlorinated solvents and SVOCs including PCBs, PAHs and dioxins, which have consistently met the very low cleanup standards that have been set.  These projects have often been implemented under performance guarantee type contracts, reducing the site owners’ risk.  Recent examples include seven chlorinated solvent DNAPL source areas treated to mean concentrations <50 ug/kg of TCE and PCE, and eight SVOC source areas treated to similarly low concentrations of PAHs and PCBs.  At a recent Brownfield site treated by ISTD, the enhanced property value that the owner derived through meeting residential cleanup standards was far greater than their remediation cost.   

Design and Performance Evaluation of Air Sparging Trench for the Treatment of VOCs and Arsenic

Omer J. Uppal, Xpert Design and Diagnostics, LLC, 22 Marin Way, Stratham, NH 03885, Tel: 603-778-1100, Fax: 603-778-2121, Email: Uppal@xdd-llc.com
Michael C. Marley, Xpert Design and Diagnostics, LLC, 22 Marin Way, Stratham, NH 03885, Tel: 603-778-1100, Fax: 603-778-2121, Email: Marley@xdd-llc.com
Dennis Keane, Xpert Design and Diagnostics, LLC, 22 Marin Way, Stratham, NH 03885, Tel: 603-778-1100, Fax: 603-778-2121, Email: Keane@xdd-llc.com
Dean Peschel, Project Manager, City of Dover, 288 Central Avenue, Dover, NH 03820, Tel: 603-743-6094, Fax: 603-742-3019, Email: dean.peschel@ci.dover.nh.us  

An air sparging trench alternative was compared to a capping/pump and treat remedy for groundwater impacted with volatile organic compounds (VOCs) and arsenic constituents of concern (COCs), as specified in a Record of Decision (ROD) at a United States Environmental Protection Agency (USEPA) Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) landfill site. The air sparging trench with an engineered backfill material was designed to intercept and treat COCs migrating with groundwater from beneath the landfill. The design and performance evaluation of the trench are presented.

The trench was designed to provide in-situ flow-through treatment of VOCs by a combination of volatilization and aerobic biodegradation, and arsenic by precipitation and sorption. Various laboratory and field-scale tests were performed to evaluate the effectiveness of the trench in removing COCs. The results of laboratory, field-scale testing, and a stripping analysis indicated that the trench could remove the majority of VOCs that are present at the site by air sparging. Organic compounds that are not expected to be completely volatilized were projected to degrade by aerobic microorganisms in the oxygenated groundwater within and down-gradient of the trench.

Geochemical modeling was performed to evaluate the ability of oxidizing conditions within trench to remove dissolved arsenic from groundwater through co-precipitation and sorption onto iron oxides. The modeling results indicated that oxidizing conditions created in the trench will result in precipitation of dissolved arsenic and other reduced minerals into the void spaces of the trench backfill material, significantly reducing the dissolved arsenic levels down-gradient of the trench.

Long-term performance issues (i.e., mineral precipitation and biofouling) observed at other air sparging trenches were evaluated and solutions for such potential issues were incorporated in the design.  The air sparging trench alternative evaluation resulted in an amendment of the original ROD with a substantial cost saving to the client.

Electrochemical Generated Alkaline Barrier for In-situ Treatment of Hexahydro-1,3,5-trinitro-1,3,5 triazine (RDX) Contaminated Groundwater

David B. Gent, Environmental Laboratory, US Army Engineer Research and Development Center, 3909 Halls Ferry Road, Vicksburg, MS 39180, Tel: 1-601-634-4822, Fax: 1-601-634-3518, Email: David.B.Gent@erdc.usace.amry.mil
Altaf H. Wani, Applied Research Associates, Inc., 119 Monument Place, Vicksburg, MS 39180 , Tel: 601 634 4820, Fax: 601-634-3518, Email: Altaf.H.Wani@erdc.usace.army.mil
Akram Alshawabkeh, Associate Professor Department of Civil and Environmental Engineering, 400 Snell Engineering Center, Northeastern University, 360 Huntington Avenue, Boston, MA 02115, Tel: 617-373-3994, 617-373-4419, Email: aalsha@neu.edu
Jeffrey L. Davis, Environmental Laboratory, US Army Engineer Research and Development Center, 3909 Halls Ferry Road, Vicksburg, MS 39180, Tel: 601-634-4822, Fax: 601-634-3518, Email: Jeffery.L.Davis@erdc.usace.amry.mil

The use, manufacturing, and storage of nitroaromatic and nitramine explosive compounds resulted in contamination of soil and groundwater.  The U.S. EPA lists hexahydro,1-3-5-trinitro-1,3,5-triazine (RDX) under the Unregulated Contaminant Monitoring Regulation for the Public in List 2.  RDX groundwater contamination causes disruptions in the use of military training areas and impacts local drinking water supplies resulting in additional costs in long term groundwater monitoring and remediation. 

Sand packed columns in a horizontal flow arrangement were used in laboratory experiments to simulate an in-situ electrochemical barrier.  The simulated barrier was used to destroy the RDX at the cathode and eliminate its downstream migration.  Mixed metal oxide coated titanium electrodes (anode and cathode) were installed in slotted PVC wells within the column to facilitate the direct and indirect destruction of RDX contaminated water by electrolysis and alkaline hydrolysis, respectively.  Over the range of inlet concentrations (0.5 to 25 mg/L), RDX removal was approximately 95% with 75% RDX destruction near the cathode, presumably by electrolysis and 13% RDX destruction downstream of the cathode by alkaline hydrolysis with applied current densities of 8 to16 A/m².  Nitroso-substituted products (MNX, DNX, and TNX) were below detection limits in the column effluent.  The effluent end products of RDX ring cleavage detected were formate, nitrite, and nitrate.  This study highlights the destructive potential of electrochemical processes for in-situ remediation of RDX contaminated water.  The significance of this 3^rd generation remediation technology is that the contaminant can be removed from the groundwater without chemical additions to the subsurface.

Chlorinated Soils Remediation Using Steam Injection Into Fractured Bedrock

Ian T. Osgerby, Ph.D, P.E, U.S. Army Corps of Engineers, New England, 696 Virginia Road, Concord, MA 01742, Tel: 978-318-8631, Fax: 978-318-8614, Email:  ian.t.osgerby@usace.army.mil
Jim Shulz CPG,  EA Engineering, Sci. & Tech., 333 Turnpike Road, Southborough, MA 01772
Greg Crisp, Crisp Environmental Services, 1059 Vernal Ave., Merced, CA 95340
Ken Manchester and Steve Antonioli, SME, MSE Technology Applications, Inc., 200 Technology Way, P.O. Box 4078, Butte, MT 59702

The former PR-58 Nike Missile battery Site was constructed in 1955/1956.  It included a missile assembly  and test building with an underground storage tank (UST), a generator building with a 4000-gal UST and personnel quarters, and was equipped with short range, conventionally-armed Nike Ajaz missiles.  The facility was deactivated in 1962.  The Army drilled holes in the bottom of the silos, backfilled them with clean sand and demolished the concrete structures surrounding the silos.  There is no site-specific documentation regarding use, storage or disposal of hazardous materials, however, a variety of chlorinated organic solvents (CVOCs) such as carbon tetrachloride (CT), tetrachloro- ethane/ethenes (PCA/PCE)and trichloro-ethane/ethenes (TCE/TCE) were typically used for parts cleaning, degreasing and preparation cleaning for painting. Typical quantities used ranged from 30 to 120 liters/month of TCE and 190 to 380 liters/month for other solvents.  The site geological units have been classified into three hydrogeological zones, an upper shallow overburden (typically glacio-fluvial sand), a deep overburden groundwater zone (sandy silty gravel to sandy gravelly silt – possibly till and a weathered bedrock zone), and a competent bedrock groundwater zone (upper 60 feet of competent bedrock).  The deep and rock units are considered as a single heterogeneous groundwater zone and all three are in hydraulic communication.  Contamination in these units is sporadic with the deep zone being the most contaminated.  Total CVOCs range from 383,700 ug/L in MW03-14D and 118,148 ug/l 80 feet west at EA-102, and non detect to the west, southwest and north.  The highest total CVOC concentration of 20,911 ug/L in the shallow competent bedrock was found in MW-03-14R.  A steam enhanced remediation (SER) pilot test was undertaken to determine whether the CVOCs could be remediated by injection of steam and air and utilizing a  dual phase vacuum extraction system.  Steam (about 1550 lbs/hr) was injected in 4 well locations with a central extraction and 6 surrounding (pneumatic control) triple well clusters screened across the 3 zones.  This injection/extraction system was centered inside a ring of perimeter wells to allow monitoring of potential impacts from thermal mobilization of the CVOCs.  The project was delayed until the unusually high water table fell to the mid screen of the upper shallow zone and the injection system was then operated for 8 weeks.  Several hundred pounds of CVOCs were extracted despite difficulties introducing steam into the series of micro fractures in the weathered and competent bedrock.  Subsurface temperatures were monitored throughout the project. 

Treatment of Trichloroethene with Reactive Nanoscale Iron Particles

Andreas D. Jazdanian, Toda America Inc., 1920 N. Thoreau Dr., Suite 110, Schaumburg, IL 60173, Tel.: 847-397-7060, Fax847-3977318, Email: andy@todaamerica.com
M. Amine Dahmani, Spectrum Analytical, Inc., 11 Almgren Drive, Agawam, MA  01001, Tel.: 800-789-9115, Fax: 413-789-4076, Email: adahmani@spectrum-analytical.com
Kenji Okinaka, Toda Kogyo Corporation, 1-1-1 Shinoki, Sanyoonoda, Yamaguchi, 756-0847, Japan, Tel: + 0836-89-0007, Fax: + 0836-88-3737, Email: Kenji_Okinaka@todakogyo.co.jp
Michael E. Miller, Camp Dresser & McKee, Inc., 50 Hampshire Street, Cambridge, MA 02139, Tel.: 617-452-6295, Fax: 617-452-8295, Email: millerme@cdm.com

The treatment of trichloroethene (TCE) impacted groundwater with laboratory grade metallic and bimetallic nanoscale materials has received considerable attention. In this work, reactive nanoscale iron particles (RNIP) that are produced in bulk (200 to 400 metric tons per year) were used for the degradation of dissolved phase TCE. The 25 % nanoiron slurry used in this study was produced by Toda Kogyo Corporation, Japan. RNIP consist of an elemental iron core (α-Fe) and a magnetite shell (Fe₃O₄). RNIP also contained unidentified sulfur compounds determined as sulfur in concentrations of about 4,000 mg/kg. The average particle size was about 70 nm, and the average surface area was about 29 m²/g. TCE degradation was studied as a function of RNIP and TCE concentration, and for different solution alkalinities and ionic strengths. The investigated initial TCE concentrations were representative of ground water source area contamination and ranged from 34 to 340 mg/L. The three different solutions used in this study consisted of deionized water, a solution with about 100 mg/L alkalinity and total ionic strength of 0.05 M, and a solution with about 400 mg/l alkalinity and total ionic strength of 0.1 M. The resulting total dissolved solids (TDS) concentrations of the batch tests were calculated to be about 2,440 to 5,027 mg/L. The investigated RNIP concentrations ranged from 1 to 8.3 g/L (total surface area of 0.86 to 7.17 m²). For static tests, overall TCE mass reductions (sum of gaseous and aqueous phase) of more than 99 % for 1 g/L RNIP and more than 99.8 % for 4.2 g/L RNIP were observed. The production of degradation products was not proportional to the TCE dechlorination. Ionic strength did not affect the degradation rate. However, the acidity resulting from the dechlorination consumed the alkalinity and diminished degradation rates.

Use of High Concentration Magnesium Sulfate Solution to Remediate Petroleum Impacted Groundwater

James F. Cuthbertson, P.E., Delta Environmental Consultants, Inc., 39810 Grand River Avenue, Suite C-100, Novi, Michigan, 48375, Tel: 248-699-0259, Fax: 248-699-0232, Email:  jcuthbertson@deltaenv.com
Jeffrey A. Kaestner, P.E., Delta Environmental Consultants, Inc., 6330 East 75^th Street, Suite 176, Indianapolis, Indiana 46250, Tel: 314-422-6251, Email: jkaestner@deltaenv.com
Lyle G. Bruce, PhD, BP Products North America Inc. – Remediation Environmental Technology, 28100 Torch Parkway, Warrenville, Illinois 60555, Tel: 630-836-7174, Email:  lyle.bruce@bp.com

Anaerobic degradation is the dominant driving force in natural attenuation of petroleum contamination in the subsurface. The contribution to natural attenuation by electron acceptors other than oxygen, such as nitrate, iron III, manganese IV, sulfate, and even carbon dioxide, has been the subject of considerable research in recent years.  Kolhatkar et al. (2000), Wiedemeier et al. (1999), and Wilson et al. (2002) have shown that of these natural anaerobic processes, sulfate reduction accounts for most of the degradation  The use of these alternative electron acceptors has been shown to have many potential advantages over the traditional approach of attempting to add dissolved oxygen to the plume.  The case studies presented will demonstrate the benefits of using high concentrations of Magnesium Sulfate solution (>10,000 mg/l) to stimulate the biodegradation of petroleum contaminants in groundwater under field conditions at various sites.  Many of these sites have had other technologies applied prior to applications.  Graphics depicting the historical concentrations and reduction trends will be provided.  In addition to the relatively rapid degradation of petroleum compounds such as BTEX, this technology is quite cost effective in comparison to other currently available remediation techniques.   A description of the technology, site selection criteria, dosage determination, and field scale performance results demonstrating contaminant concentration reductions in groundwater of more than 90% within a few months at some sites will be presented.  Magnesium Sulfate was selected for use due to availability, low cost, high solubility and the relative safety associated with handling.  This technology has advantages over others for many sites where physical limitations (buildings, utilities, etc.) preclude other technologies.

Completion of In-Situ Thermal Remediation of PAHs, PCP and Dioxins at a Former Wood Treatment Facility

John M. Bierschenk, TerraTherm, Inc., 356 Broad Street, Fitchburg, MA 01420, Tel: 978-343-0300, Fax: 978-343-2727, Email: jbierschenk@terratherm.com
Ralph S. Baker, TerraTherm, Inc., 356 Broad Street, Fitchburg, MA 01420, Tel: 978-343-0300, Fax: 978-343-2727, Email: rbaker@terratherm.com
James P. Galligan, TerraTherm, Inc., 356 Broad Street, Fitchburg, MA 01420, Tel: 978-343-0300, Fax: 978-343-2727, Email: jgalligan@terratherm.com
Ronald Young, TerraTherm, Inc., 356 Broad Street, Fitchburg, MA 01420, Tel: 978-343-0300, Fax: 978-343-2727, Email: ryoung@terratherm.com

The largest in situ thermal conduction heating project ever undertaken at a wood treatment site was completed in March 2006.  The site was a former utility pole treatment facility that Southern California Edison (SCE) operated from 1921 to 1957.  

The subsurface soils were contaminated primarily with polyaromatic hydrocarbons (PAHs), pentachlorophenol (PCP), dioxins and furans, with soil treatment standards of 0.065 mg/kg benzo(a)pyrene Toxic Equivalents, 25 mg/kg PCP, and 1.0 mg/kg dioxin, expressed as 2,3,7,8-tetrachlorodibenzodioxin (TCDD) Toxic Equivalents (TEQ).  A feasibility study led to the selection of TerraTherm’s patented In-Situ Thermal Destruction (ISTD) technology, which utilizes simultaneous application of thermal conduction heating and vacuum to treat contaminated soil without excavation.  The applied heat volatilizes organic contaminants within the soil, enabling them to be carried in the vapor stream toward heater-vacuum wells.  Subsurface temperature monitoring tracked the progress of heating.   A heating goal for inter-well temperatures of 325°C (620°F) was achieved, as were all the soil treatment standards and air emission standards.

Approx. 16,500 CY of predominantly silty soil was treated to a maximum depth of 105 ft. TerraTherm installed 785 thermal wells, including 654 heater-only and 131 heater-vacuum wells, in a hexagonal pattern at 7.0-foot spacing.

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