Demonstration of a Fractured Rock Geophysical Toolbox for Characterization and Monitoring of DNAPL Biodegradation in Fractured Rock Aquifers
ER-201118
Objective
The overall objective of this project is to demonstrate a method for characterization and monitoring of dense non-aqueous phase liquid (DNAPL) biodegradation (including free and dissolved phase) in fractured rock aquifers based on a fractured rock geophysical toolbox (FRGT). Specific technical objectives include demonstrations of (1) fracture network characterization using geophysical methods sensitive to fracture strike and dip patterns and spanning a wide range of measurement scales; (2) long-term, minimally invasive autonomous monitoring of proxies of the timing and extent of amendment delivery and/or DNAPL degradation in fractured rock using combined geophysical and geochemical measurements sensitive to biodegradation; (3) the application of "informed" inversion to produce estimates of fracture location, distribution, and orientation with better resolution than is currently possible with commercially available tools; and (4) identification and monitoring of geophysical attributes that are soft measures of progress of DNAPL biodegradation in fractured rock. The project team aims to demonstrate how such geophysically imaged "soft" hydrological information can be used to guide decisions regarding sampling frequency and duration. This effort will include comparison of dense 4D geophysical monitoring results with sparser (in time and space) point chemistry data in order to fully understand geophysical signatures of DNAPL amendment treatments and remediation processes.
Technology Description
For the characterization component of the FRGT, this project will demonstrate the performance of four under-exploited technologies: (1) directional borehole ground penetrating radar (DBHGPR) for providing unique high-resolution data on fracture strike and dip; (2) resistivity and induced polarization (IP) imaging for visualizing the spatial distribution of fracture density and fracture surface area; (3) azimuthal self potential (ASP) for determining spatial variability in bulk hydraulic anisotropy in fractured bedrock; and (4) new borehole IP and nuclear magnetic resonance (NMR) tools for improving assessment in vertical distribution of physical parameters controlling mass transfer. For the DNAPL monitoring component of the toolkit, this project will demonstrate the performance of (1) electrical resistivity imaging for tracking changes in bulk conductivity sensitive to changes in groundwater chemistry accompanying DNAPL degradation, (2) self potential (SP) imaging of the changes in the distribution of natural current sources resulting from redox zonation produced by DNAPL degradation, and (3) electrodic potential (EP) monitoring of changes in redox chemistry local to electrodes. The data analysis component will demonstrate how new inversion technologies can (1) better characterize fracture networks in terms of bulk conductivity, chargeability, and source current, respecting specialized model constraints derived from borehole, ASP, and DBHGPR data and (2) reconstruct the changes in geophysical attributes that are related to DNAPL biodegradation using constraints that are encouraged to limit changes within the images to discrete fractures or fracture zones identified during the characterization phase.
Benefits
Current technologies for monitoring DNAPL biodegradation in fractured rock rely heavily on direct measurements in wells and thus are expensive and time consuming and provide limited spatial and temporal information. The technology to be demonstrated requires far fewer wells for monitoring the progress of amendment delivery and subsequent DNAPL biodegradation in fractured rock and permits more expensive direct investigations of DNAPL chemistry to focus on target regions identified via the FRGT, thereby increasing efficiency. Potentially large cost savings will ultimately result from replacing many labor intensive, expensive direct sampling events (e.g., groundwater chemistry analysis from boreholes) with geophysical monitoring events that will, after initial investment in performance site setup, demand only a fraction of the cost. Cost savings in characterization and monitoring also translate into cost savings for cleanup by enabling optimization of remedial system design. (Anticipated Project Completion - 2014)
Points of Contact
Principal Investigator
Dr. Lee Slater
Rutgers University-Newark
Phone: 973-353-5109
Fax: 973-353-1965
Document Types
- Fact Sheet - Brief project summary with links to related documents and points of contact.
- Final Report - Comprehensive report for every completed SERDP and ESTCP project that contains all technical results.
- Cost & Performance Report - Overview of ESTCP demonstration activities, results, and conclusions, standardized to facilitate implementation decisions.
- Technical Report - Additional interim reports, laboratory reports, demonstration reports, and technology survey reports.
- Guidance - Instructional information on technical topics such as protocols and user’s guides.
- Workshop Report - Summary of workshop discussion and findings.
- Multimedia - On demand videos, animations, and webcasts highlighting featured initiatives or technologies.
- Model/Software - Computer programs and applications available for download.
- Database - Digitally organized collection of data available to search and access.