Verification Monitoring for In Situ Chemical Reduction Using Zero-Valent Zinc, A Novel Technology for Remediation of Chlorinated Alkanes

Dr. Rula Deeb | Geosyntec Consultants

ER-201628

Objective

201628_graphic

The reactivity profile of “lesser chlorinated” aliphatic hydrocarbons such as 1,2-dichloroethane and 1,2-dichloropropane is less understood than those of compounds such as tetrachloroethene and trichloroethene and has not been systematically considered when developing remedial approaches for these compounds. The lesser chlorinated hydrocarbon 1,2,3-trichloropropane (TCP) has been identified as an emerging contaminant at Department of Defense (DoD) facilities. To date, TCP has been observed at more than 45 installations. The median detected concentrations have been low, but are nonetheless high relative to regulatory levels for TCP. Remediation options for TCP are limited, although one treatment process that produces promising rates of TCP degradation is reduction with zero-valent zinc (ZVZ). The objective of this project is to collect enough data to fully demonstrate and validate ZVZ, including providing supporting information for engineering design, performance assessment, regulatory approval, and cost benefit analysis. This work will leverage data collected as part of a previous Navy-funded pilot study and collect additional data to develop performance metrics evaluating ZVZ delivery and treatment efficacy.

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Technology Description

In 2014, the Navy implemented a pilot study to evaluate the feasibility and performance of in situ ZVZ remediation of TCP in groundwater. The pilot study included the direct injection of ZVZ into the subsurface, followed by periodic monitoring of TCP, dissolved zinc, and geochemical parameters in nearby performance monitoring wells. The pilot study results showed evidence of TCP degradation, but the pilot study monitoring was not designed to evaluate efficacy of the ZVZ injections or long-term performance of the zinc media with respect to degradation of lesser chlorinated hydrocarbons such as TCP. This ESTCP project will leverage the previous DoD-funded work and collect additional information necessary to fully validate ZVZ as a remedial technology for TCP and other lesser chlorinated hydrocarbons. The team will conduct supplemental groundwater sampling to evaluate long-term TCP degradation efficacy and soil sampling to more fully assess the distribution of ZVZ within the pilot study injection area.

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Benefits

Current approaches for remediating TCP in groundwater are infeasible or cost prohibitive. Since TCP has been identified as an emerging contaminant for DoD facilities, successful development and transition of ZVZ technology can help lead to expedited facility cleanup and closure. This project will develop a decision framework that allows project managers to evaluate the applicability and feasibility of the ZVZ technology based on site conditions and contaminants of interest, along with an approach and methodology for designing and implementing the technology. In addition, ZVZ technology may be more broadly applicable to the wider family of lesser chlorinated hydrocarbons, a particularly recalcitrant class of compounds that is challenging to remediate. (Anticipated Project Completion - 2019)

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Points of Contact

Principal Investigator

Dr. Rula Deeb

Geosyntec Consultants

Phone: 510-285-2676

Program Manager

Environmental Restoration

SERDP and ESTCP

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