Impacts of Chemical Oxidation on Aquifer Conditions and Microbial Activities
Robert Luhrs, Raytheon, Waltham, MA

Sequential Application of Chemical Oxidation Using Permanganate and Bioaugmentation
Dave Major, GeoSynthec Consultants, Guelph, ON

Tools for Designing and Monitoring the Performance of Combined Remediation
Thomas Christy, Technologies Geoprobe, Salina, KS  

Overview of Technical and Policy Developments in Combining In-Situ Remedies to Address Non-Aqueous Phase Liquid Contamination

Jim Cummings, Technology Assessment  Branch/OSRTI/OSWER, USEPA (5203P), 1200 Pennsylvania Ave NW, Washington, DC 20460, Tel: 703-603-7197, Fax: 703-603-9135, Email: cummings.james@epa.gov

While environmental remediation literature has contained references to 'treatment trains' for a decade or more, the last 3-5 years have seen a significant increase in actual field deployments to address Non-Aqueous Phase Liquid (NAPL) contamination.  In some cases, combining remedies is post-hoc -e.g.,, practitioners notice something 'interesting' in the latter stages of a project or  supplement or replace older systems such as pump and treat with other technologies in an effort to enhance performance and achieve site closure.  In other cases, as familiarity with combining remedies has increased, practitioners are designing treatment trains from the outset of remedial design and remedial action. Effective combination of technologies to improve ability to achieve remedial action objectives and/or to reduce cost and performance uncertainties requires both technical and policy adjustments to historical practice.  This presentation will provide a national overview on current practices and policies, discussing prevalent technology combinations and needed policy adjustments in the area of more flexible decision documents.

Impacts of Chemical Oxidation on Aquifer Contaminants and Microbial Activity

Robert C. Luhrs, Raytheon Company, 235 Wyman Street, Waltham, MA 02451, Email: robert_c_luhrs@raytheon.com

In-situ chemical oxidation has become an accepted remedial approach for projects containing an assortment of volatile organics.  As this technology has gained industry acceptance, the results from some projects have begun to become public, with varying levels of success.  Some found little to no contaminant degradation and claimed failure, while others have shown remarkable results.  This presentation has been prepared to review the topic from a broad perspective, using lessons learned from multiple projects around the country to better understand chemical trends, impacts to the microbiology, and contaminant rebound after large injection programs.

Sequential Application of Chemical Oxidation Using Permanganate and Bioaugmentation

David Major, GeoSyntec Consultants, 130 Research Lane, Suite 2, Guelph, Ontario, Canada N1G 5G3, Tel: 519-822-2230, Fax: 519-822-3151, Email: dmajor@geosyntec.com
Eric Hood, GeoSyntec Consultants, 130 Research Lane, Suite 2, Guelph, Ontario, Canada N1G 5G3, Tel: 519-822-2230, Fax: 519-822-3151, Email: ehood@geosyntec.com
Philip Dennis, SiREM, Research Lane, Suite 2, Guelph, Ontario, Canada N1G 5G3, Tel: 519-822-2265, Fax: 519-822-3151, Email: pdennis@siremlab.com

ISCO using permanganate and in situ bioremediation/ bioaugmentation are promising technologies for the treatment of DNAPL source areas.  Both technologies have completed laboratory research and development and have been successfully demonstrated in pilot tests and full-scale applications; however, each technology has limitations that can affect the cost or duration of the approach.  Enhanced bioremediation is being implemented at sites previously treated using permanganate, typically in response to post-ISCO monitoring data indicating that a rebound in contaminant concentrations has occurred. A research program was recently completed to demonstrate the efficacy of coupling in situ chemical oxidation (ISCO) to rapidly remove accessible DNAPL mass with in situ bioremediation via biostimulation or bioaugmentation to degrade and contain the remaining mass.  

The results of this study provide several significant conclusions including: a) while permanganate may have strong disinfecting properties, recolonization of the permanganate treatment zone by indigenous microorganisms appears to occur rapidly (i.e. weeks to months) with only subtle differences between the pre- and post-treatment microbial communities which are not readily distinguished using widely available microbial characterization tools (e.g., PLFA, plating, MPN etc.); b) the extremely high manganese oxide (MnO₂) concentrations (1,000 to 10,000 mg/kg) in the permanganate treatment zone is unlikely to be significantly mobilized into groundwater during bioremediation; and c) the deposition of manganese oxide (MnO₂) is particular problematic since MnO₂ (an alternate electron acceptor) competitively inhibits reductive dechlorination of both cis-DCE and VC, limiting the performance of enhanced bioremediation in zones where MnO₂ is present. 

This presentation will provide an overview of the results from these three aspects of the research program, draw conclusions for the applicability of the technology for DNAPL remediation and provide recommendations for a best-practice approach for future work with the sequential technologies.

Tools for Designing and Monitoring the Performance of Combined Remediation

Thomas M. Christy, P.E., Geoprobe Systems, 601 N. Broadway, Salina, KS  67401, Tel: 785 825 1842, Fax:  785 825 6983, Email: christyt@geoprobe.com

Chemical and biological technologies for in-situ remediation have grown markedly over the past decade.  Never before have so many tools been available to effect the remediation of subsurface contaminants.  However, as the list of successful remediation projects grows, so does the list of projects in which remediation materials were misapplied or wasted via application in essentially uncontaminated areas.   Nearly every  remediation specialist can cite a case that failed because treatment materials and contaminant mass failed to meet.  In a similar manner, almost every remediation specialist can cite projects in which the final efficacy of a treatment regime remains unknown due to lack of appropriate follow-on performance monitoring.  This paper will discuss methods for logging subsurface lithology, contaminant distribution, and permeability that can aid in site characterization and thereby enhance remediation efficiency.  The logging methods discussed will include MIP, which has been used both in remediation design and performance monitoring; CPT,  which has been used extensively in lithologic characterization; and a new tool, HPT, which gives very useful permeability information and can be used to direct mater injection efforts.  Examples will be presented from the use of these tools on remediation sites. 

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