Application of Electrochemical Techniques for the Remediation of Soils Contaminated with Organic Pollutants
Elisa Ferrarese, University of Trento, Trento, Italy

Comparison of Remedial Systems Employed at Drycleaner Sites
Bob Jurgens, Kansas Dept. of Health & Environment, Topeka, KS

Adjustable Depth Air Sparging Case Study
Michael C. Marley, XDD, LLC, Stratham, NH  

Remediation of Asbestos in Soil under the New Massachusetts Department of Environmental Protection Regulations
James R. Fair, PE, M.S., Prasanta K. Bhunia, PhD, LSP, Weston & Sampson Engineers, Inc.

Five-Year Performance Evaluation of a Permeable Reactive Barrier, Needham, Massachusetts
Peter Richards, Massachusetts Department of Environmental Protection, Wilmington, MA

Re-Remediating: Post-Closure Excavation after Source Zone Translocation and MNA Ineffectiveness – A Case Study
Stephen J. Druschel, Nobis Engineering, Inc., Lawrence, MA

Application of Electrochemical Techniques for the Remediation of Soils Contaminated with Organic Pollutants  

Student Presenter

Elisa Ferrarese, University of Trento, Department of Civil and Environmental Engineering, Via Mesiano 77, 38050 Trento (TN), Italy, Tel:  +390461882635, Fax: +390461882672
Gianni Andreottola, University of Trento, Department of Civil and Environmental Engineering, Via Mesiano 77, 38050 Trento (TN), Italy, Tel:  +39 0461 882681, Fax: +39 0461 882672

Direct Current Technologies (DCTs) are techniques for contaminated soil remediation, in which an electrical field is created in the polluted medium by applying a low-voltage direct current across electrodes placed in the ground. This study aimed to evaluate the feasibility of using DCTs for the remediation of different organic contaminants from various types of fine grain soils and sediments. For this purpose, a one-dimensional experimental setup for bench scale testing was assembled, and several laboratory tests were performed. The experimental setup included an electrochemical cell, two stainless steel plate electrodes, a stabilized DC generator and tanks for the pore fluid collection.

Two types of soils contaminated by diesel fuel and sediments polluted by polycyclic aromatic hydrocarbons (PAHs) were considered in this investigation. In the experiments the contaminant  removal was evaluated under the influence of the electric current generated by a constant potential difference (0.5-6 V/cm) for a fixed period of time (7-28 days). The results showed that a good degree of organic pollutant removal could be achieved via electrochemical methods. About 90% contaminant removal was achieved for PAH-contaminated sediments after a four-week treatment, while the tests with diesel fuel-contaminated soils resulted in about 45-55% TOC removal and 70-85% TPH removal. The main factors influencing the process seem to be the process duration and the soil mineralogy, especially the iron content of the treated medium. On the opposite, the applied voltage seems to have a limited influence on the contaminant removal efficiency, good results being achieved with specific voltages as low as 1 V/cm. The results achieved suggest that DCTs can be effectively used for the mineralization of many organics with low energy expenditure, especially in very fine soils, like clays, which are often more difficult to treat with conventional chemical methods, because of their low permeability and high sorption capacity.

Comparison of Remedial Systems Employed at Drycleaner Sites

Bob Jurgens, Kansas Dept. of Health & Environment, 1000 SW Jackson, Suite 410, Topeka, KS 66612-1367, Tel: 785-291-3250, Fax: 785-296-4823
William Linn, Florida Dept. of Environmental Protection, 2600 Blair Stone Road - M.S. 4520, Tallahassee, FL, 32399, Tel: 850-245-8927, Fax: 850-922-4368
Nancy Boisvert, Tennessee Drycleaner Environmental Response Program, 4th Floor, L&C Annex, 401 Church St., Nashville, TN 37243, Tel: 615-253-3876, Fax: 615-741-1115

The State Coalition for Remediation of Drycleaners (SCRD) analyzed data from over one hundred site profiles collected from drycleaning site remediation projects across the United States.  The comparative analysis evaluates the various remedial technologies and assessment techniques used at chlorinated and petroleum solvent sites.  Site data included physical site characteristics, hydrogeology, geology, soil/groundwater contaminant concentrations and distribution, remedial systems employed, site closures, and costs.  The paper presents a current snapshot of remedial technologies being employed in most of the states with programs dedicated to remediation of contaminated drycleaning sites.  Although conventional remedial technologies have been utilized at many of these sites, chemical oxidation and bioremediation are being employed more frequently.  Bioremediation has been employed at over 23% of the sites in this study; while, chemical oxidation was used at 23.3% of the sites.

Site data were analyzed to determine trends regarding remediation successes or failures.  Success and/or failure are often difficult to ascertain because of site and program limitations.  Some useful observations can however be made regarding certain technologies.   Graphical analysis of the data can indicate trends in remediation technology selection.  The technology selection process is driven by a variety of technical and programmatic factors, such as: physical site limitations, cost, desired cleanup time, risk-based determinations and expertise of remedial design staff or consultants.  Ideally, the audience will be able to use the information in this report to help in the decision-making process when selecting a proven remediation technology for their drycleaning site, or at a site with similar characteristics.  When completed, the paper will be available on the SCRD Web Page at www.drycleancoalition.org.

Adjustable Depth Air Sparging Case Study

Michael C. Marley, XDD, LLC, 22 Marin Way, Unit 3, Stratham, NH 03885, Tel: 603-778-1100, Fax: 603-778-2121, Email: marley@xdd-llc.com
Matthew T. Walsh, XDD, LLC, 1275 Glenlevit Dr. Ste. 100, Allentown, PA 18106, Tel: 484-224-3031, Fax: 484-224-2999, Email: Walsh@xdd-llc.com
Andrew S.  Drucker, Naval Facilities Engineering Service Center, Code OP423, 1100 23rd Avenue, Port Hueneme, CA 93043, Tel: 805-982-1108, Fax: 805-982-4832, Email: andrew.drucker@navy.mil

Air Sparging is a commonly deployed environmental remediation technology by which pressurized air is injected into a contaminated groundwater zone to remove harmful volatile contaminants.  The injected air strips the contaminants from a liquid phase to a vapor phase and transports the volatile compounds via air channels to the unsaturated zone.

The extent of air distribution within the remedial zone of an air sparging site affects the level of contact between the air and the target contaminants and therefore is one of the primary factors leading to a site’s successful cleanup. Typically, the greater the uniform air distribution, the greater the contaminant removal rate.   Present systems use discrete depth air sparge wells to inject into the subsurface.  It has been demonstrated that by varying air injection depth using a composite set of wells, one is able to increase the level of air distribution and therefore significantly improve upon remedial performance.

The Navy has developed a new and innovative technology called Adjustable Depth Air Sparging (ADAS) that is applied within a single air sparge well with infinite adjustability. The technology has the capability to be used with conventional air sparging equipment and methods to help increase overall air distribution and therefore lower project costs and improve cleanup performance.

Results from a site demonstration conducted by XDD at a Superfund Site in NJ of the ADAS system will be presented.  Testing of the ADAS system showed that air could be injected at a variety of depth intervals in a single well by simply raising and lowering the technology’s packer system. The results confirmed that vertical adjustments to sparging depth clearly influenced and improved the achievable mass removal rate at the demonstration site.  

Remediation of Asbestos in Soil under the New Massachusetts Department of Environmental Protection Regulations

James R. Fair, PE, M.S., Weston & Sampson Engineers, Inc., 5 Centennial Drive, Peabody, MA, 01960, Tel: 978-532-1900 ext. 2334, Fax: 978-977-0100, Email: fairj@wseinc.com.
Prasanta K. Bhunia, PhD, LSP, Weston & Sampson Engineers, Inc., 5 Centennial Drive , Peabody , MA, 01960, Tel: 978-532-1900 ext. 2287, Fax: 978-977-0100, Email: bhuniap@wseinc.com

The public involvement, pilot study, and construction processes implemented to remediate asbestos-contaminated soil at a former industrial dumping area in Massachusetts will be presented.  Because the asbestos-contaminated site is located within a high profile and densely populated area, innovative approaches to perform the work effectively and safely with public confidence is essential.  The project will be conducted in accordance with the recently revised Department of Environmental Protection (DEP) asbestos in soil regulations, and will include conducting an innovative pilot study to help gain public support.  In addition to the pilot study, the full-scale remediation process and Best Management Practices (BMP) to be implemented to achieve No Significant Risk (NSR) will be discussed, along with a review of the current asbestos in soil regulations.  Asbestos in soil analytical methods and risk-based closure approaches utilizing the Superfund Elutriator method and the DEP activity-based sampling method will also be presented.

Five-Year Performance Evaluation of a Permeable Reactive Barrier, Needham, Massachusetts

Peter Richards, Massachusetts Department of Environmental Protection, Bureau of Waste Site Cleanup, 205B Lowell Street, Wilmington, MA 01887, Tel: 978 694-3361, Email: peter.richards@state.ma.us

In July 2001 the Massachusetts DEP installed a permeable reactive barrier (PRB) to treat a groundwater plume of chlorinated solvents migrating from an electronics manufacturer in Needham, Massachusetts toward the Town of Wellesley’s Rosemary Valley wellfield.  The primary contaminant of concern at this site is trichloroethene (TCE), which at the time had a maximum average concentration of approximately 300 micrograms per liter directly upgradient of the PRB.  The PRB is composed of a mix of granular zero-valent iron filings and sand with a  pure-iron thickness design along its length between 0.6 and 1.7 feet.  The PRB was designed to intercept the entire overburden plume; previous study had indicated that the contaminant flux in the bedrock was negligible.  Groundwater samples have been collected from monitor wells upgradient and downgradient of the PRB on a quarterly basis since installation.  Inorganic parameters such as oxidation/reduction potential, dissolved oxygen and pH are also measured to determine stabilization during the sampling process.  Review of the analytical data indicates that the PRB is significantly reducing TCE concentrations along its length.  However, in two discrete locations TCE concentrations show little decrease in the downgradient monitor wells, particularly in the deep overburden.  Data available for review include the organic and inorganic analytical data, slug test results from nearby bedrock and overburden wells and upgradient and downgradient water level information.  These data will aid in refining the conceptual site model for the PRB and in evaluating its performance.

Re-Remediating: Post-Closure Excavation after Source Zone Translocation and MNA Ineffectiveness – A Case Study

Stephen J. Druschel, PhD, PE, Nobis Engineering, Inc., 439 South Union Street, Bldg 2, Suite 207, Lawrence, MA  01843-2800, Tel: 978-722-1005, Email: sdruschel@nobisengineering.com
Jay Snyder, Vener Mustafin, Teri McMillan, Golder Associates, Inc., 4910 Alameda Boulevard NE, Suite A, Albuquerque, NM 87113, Tel: 505-821-3043, Fax: 505-821-5273
Patrick DeGruyter, New Mexico Environment Department, 5500 San Antonio Driver, NE, Albuquerque, NM 87101, Tel: 505-222-9562

High concentrations of benzene and other petroleum constituents were measured in the groundwater and soils beneath a former filling station in Gallup, New Mexico, fifteen years after leaking underground storage tank closure and removal. The persistence of the constituent concentrations indicated the inability of monitored natural attenuation (MNA) to successfully remediate the site soils and achieve cleanup goals. Subsurface investigation results suggested source zone translocation caused by non-aqueous phase liquid (NAPL) migration in response to pumping well drawdown of the phreatic surface, and subsequent impact to new soils as a smear zone. Mitigation of human exposure, funding availability and the likelihood of upcoming redevelopment led to the decision to excavate the expanded source to a depth of 16 feet below ground surface and an estimated volume of 2500 cubic yards. Simple in concept, the excavation was constrained by limitations on equipment access, slope stability, and the need to protect surrounding utilities, sidewalks and streets. Backfill material was selected to provide low compressibility and high bearing capacity, while being based on local availability. A detailed protocol for monitoring slope movements was implemented and strict limits imposed on personnel access to the excavation areas, to reduce risks from excavation instability while balancing the need for stable, compacted backfill. Air emissions required OSHA Level B protections and impacted nearby businesses, triggering adjustments to the excavation sequence. Off site hauling and the requirements for truck traffic through the surrounding community controlled the project schedule, while insufficient stockpile areas dictated the site layout and operation. Evaluation of this project provides a design template for similar projects of post-closure source excavation in urban areas.

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