U.S. EPA Contaminated Site Cleanup Information (CLU-IN)

U.S. Environmental Protection Agency
U.S. EPA Technology Innovation and Field Services Division

Dense Nonaqueous Phase Liquids (DNAPLs)

Detection and Site Characterization

Monitoring of In Situ Remediation Efforts

Most remote geophysical techniques have difficulty identifying DNAPL residual or pool zones. They have been shown, however, to be able to trace NAPL movement in the subsurface, as well as steam fronts and ionic liquids. This ability makes them useful in showing that all areas of concern have been covered by a steam front; the ionic mixtures of Fenton's reagent, permanganates, and persulfates are covering the area planned from their injection points; and biostimulants like emulsified oils are spreading as intended. Radon measurement has shown promise in some situations for estimating the amount of DNAPL removed from a source zone, i.e., for evaluating the amount of radon flux before and after the application of a remedy. An increase in flux is related to a decrease in NAPL volume. The same technique has been applied with partitioning tracer liquids and gases.

For Further Information

Adobe PDF LogoDevelopment of Radon-222 as a Natural Tracer for Monitoring the Remediation of NAPL in the Subsurface
B.M. Davis, L. Semprini, and J. Istok.
DOE/ER/62523, 121 pp, Feb 2003

This study evaluated whether naturally occurring radon-222 in ground water can be used as an in situ partitioning tracer to characterize DNAPL saturations. The laboratory and field push-pull tests demonstrated that radon retardation occurs in the presence of TCE and LNAPL and that radon retardation can be used to calculate TCE saturations; however, nonequilibrium radon partitioning and heterogeneous TCE distributions may affect the retardation factors and TCE saturation estimates.

Adobe PDF LogoStrategies for Monitoring the Performance of DNAPL Source Zone Remedies
Interstate Technology & Regulatory Council, 205 pp, 2004

This document is intended for state environmental regulators and others interested in learning about approaches to performance monitoring while implementing various in situ technologies for the treatment of DNAPLs. Despite the ever-increasing number of field applications of DNAPL removal technologies, many unanswered questions remain regarding the effectiveness of these technologies and how best to measure their performance with respect to site-specific remedial objectives. Currently, there is no clear consensus based on objective guidelines as to the best way to evaluate treatment performance and balance performance objectives against site-specific stratigraphy, measurement uncertainties, regulatory acceptance, and cost. The best approach is for site owners, regulators, and stakeholders to understand the options available and the benefits and limitations of each so that informed decisions can be made. The primary purpose of this document is to provide that knowledge base. It presents several ways in which the success or failure in treating a DNAPL source zone has been measured and contains several succinct case studies that cover remedial goals and objectives, performance monitoring and verification, and lessons learned.

Adobe PDF LogoUse of Borehole Radar Methods and Borehole Geophysical Logs to Monitor a Field-Scale Vegetable Oil Biostimulation Pilot Project at Fridley, Minnesota
J.W. Lane, C.C. Casey, F.D. Day-Lewis, A. Witten, R.J. Versteeg.
Proceedings of the Fourth International Conference on Remediation of Chlorinated and Recalcitrant Compounds, May 24-27, 2004, Monterrey California.

Based on a comparison of pre- and post-injection data sets, a conceptual model was developed to define the distribution of emulsified vegetable oil and the extent of ground water having altered chemistry resulting from injections and, possibly, enhanced microbial degradation of chlorinated hydrocarbons. Radar slowness (reciprocal velocity) anomalies indicate that the emplaced oil emulsion remained close to the injection wells, whereas attenuation anomalies indicate changes in groundwater chemistry downgradient of all three injections.

Abstracts of Journal Articles

Application of Borehole Radar for Monitoring Steam-Enhanced Remediation of a Contaminated Site in Fractured Limestone, Maine, USA

Automated Geophysical Monitoring of In Situ Engineered Treatments

Can Geoelectrical Methods Be Used to Monitor Non-Aqueous Phase Liquid Remediation Efforts?

DC Resistivity Monitoring of Potassium Permanganate Injected to Oxidize TCE In Situ

Difference Inversion of ERT Data: a Fast Inversion Method for 3-D In Situ Monitoring

Effect of Precipitation on Low Frequency Electrical Properties of Zerovalent Iron Columns

Electrical Imaging of Tracer Migration at the Massachusetts Military Reservation, Cape Cod

Electrical Resistance Tomography

Electrical Resistance Tomography for Steam Injection Monitoring and Process Control

Evaluation of Permeable Reactive Barrier (PRB) Integrity Using Electrical Imaging Methods

Field Evaluation of Interfacial and Partitioning Tracers for Characterization of Effective NAPL-Water Contact Areas

GPR Monitoring of a DNAPL Release in a Natural Groundwater Flow Field

Geophysical Monitoring of Vegetable Oil Emulsion Biostimulation Using Cross-Hole Radar Methods

Investigating the Potential for Long-Term Permeable Reactive Barrier (PRB) Monitoring from the Electrical Signatures Associated with the Reduction in Reactive Iron Performance

Monitoring In-Situ Cleanup Using Resistivity Imaging

Monitoring Partitioning Tracer Testing and Surfactant Flooding by In-Line Gas Chromatography Techniques

Monitoring a Field-Scale Biostimulation Pilot Project Using Cross-Hole Radar and Borehole Geophysical Methods

Object-Based Inversion of Crosswell Radar Tomography Data to Monitor Vegetable Oil Injection Experiments

Object-Based Inversion of Crosswell Radar Tomography Data to Monitor Vegetable Oil Injection Experiments

Partitioning Tracer Tests as a Remediation Metric: Case Study at Naval Amphibious Base Little Creek, Virginia Beach, Virginia

The Role of Advanced Monitoring in Steam Stripping for In-Situ Remediation of DNAPL

Self Potential Observations during DNAPL Dissolution

Self-Potential (SP) and Active Electrical Geophysical Assessment of Bioremediation at a Contaminated Gasworks Plant

Synthetic and Field Based Electrical Imaging of a Zerovalent Iron Barrier: Implications for Monitoring Long-Term Barrier Performance

Tracers as Tools for Design and Evaluation of Injection-Based In Situ Groundwater Remediation Systems

Use of Borehole Radar Methods and Borehole Geophysical Logs to Monitor a Field-Scale Vegetable Oil Biostimulation Pilot Project at Fridley, Minnesota

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