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Brownfield Assessment – Mapping The Unknowns Below With Geophysical Tools
Article by: Hannah Peterson | hydroGEOPHYSICS
A brownfield site is a former commercial or industrial site where future use is potentially affected by historic contamination. At first glance, brownfield sites may seem like easy targets for revitalization and improvement by municipalities and developers. However, brownfield sites often contain hidden subsurface infrastructure and contamination associated with previous activities. The unknowns associated with historical activities present a significant challenge to revitalizing an area. Contamination in the subsurface can stop revitalization in its tracks, causing renewal to languish in cities and communities across the US.
Brownfield sites often contain hidden subsurface infrastructure and contamination associated with previous site activities
Geophysics offers a cost-effective, non-invasive, and safe approach to assessing brownfield sites through its ability to locate subsurface contaminants and infrastructure without costly drilling, potholing, and other invasive actions. Advanced knowledge of subsurface challenges before demolition or construction can be critical for controlling costs, schedules, and safety. HGI makes it easy to understand brownfield surveys, and we will provide multiple imaging solutions for targeting subsurface infrastructure and contamination while making the process seamless from start to finish.
Geophysics offers a cost-effective and safe approach to assessing brownfield sites through its ability to locate subsurface contaminants and infrastructure.
Example brownfield sites to consider are: abandoned gas stations, dry cleaners, and closed factories. Frequently, the conditions of these sites are unknown due to a lack of historical information. Efforts to characterize and clean up these sites are critical as they pose environmental health and safety challenges, and reuse provides a sustainable approach for a growing population and commercial development. Current estimates suggest that there are more than half a million brownfield sites in the US, with typical subsurface hazards of building infrastructure and environmental contaminants.
HGI performed multi-technique geophysical survey at Hanford, a Department of Energy (DOE) nuclear site. The photo shows a layered result with electromagnetic and magnetic data.
Various geophysical tools can characterize brownfield sites by identifying the location, volume, and extent of contaminants, pollutants, or infrastructure. Geophysics works through its capacity to measure physical properties in the subsurface. Additionally, using more than one geophysical method to define multiple physical properties can often capture the full spectrum of subsurface material for an increased understanding of the site. Geophysical data can differentiate contaminated materials from surrounding soil or rock, accurately mapping out suspected hazardous compounds. Electromagnetic (EM) induction can detect electrically conductive waste and metal in the subsurface. Magnetic data can reinforce the location of subsurface infrastructures, such as tanks and pipes, by measuring local magnetic responses from ferrous materials. The electrical resistivity method will delineate subsurface contaminants in the pore spaces of soil and rock. Finally, ground-penetrating radar (GPR) can successfully locate utilities and subsurface tanks, as it finds areas of differing electrical properties.
The electrical resistivity method was used to image a Superfund site. The profile is one of five lines that were collected in order to look for nitrogen-nitrate, which would make the subsurface more electrically conductive than the surrounding soil or rock.
It is recommended that geophysics be the first tool for in-field characterization efforts! The technology offers inexpensive insight through targeting unknown and costly subsurface anomalies before performing any other invasive groundwork. Revealing subsurface environmental and construction challenges upfront allows for better and more cost-efficient decision-making, ultimately saving time, financial resources and improving health and safety throughout the project and into the future.
Geophysics should be the first tool for in-field characterization efforts!
HGI has more than 30 years of experience applying geophysics to brownfield sites, saving our clients time and money with targeted information on subsurface brownfield characteristics. But we offer more than this. Our clients realize meaningful cost savings over other methodologies with benefits delivering value for your core needs:
Benefits & Features of Geophysical Methods for Brownfields:
- Savings in drilling costs.
- HGI surveys can provide the optimum drilling locations reducing drilling needs, and shortening time to remediation and construction, saving you money
- Geophysical subsurface characterization maps target areas of concern.
- Accurate infrastructure location results for fast and targeted removal and rapid site recovery.
- Multiple method confirmation data sets enhancing understanding and reducing false positives.
- Geophysics offers a faster return to compliance with rapid data acquisition and interpretation.
- Removes the guess work from designing characterization programs.
- Geophysics enhances informed decision making during remedial planning reducing rework and increasing safety.
- Extends the value of borehole data.
- By combining geophysical data and borehole data, geophysics can help better define gaps in drilling programs allowing for more efficient planning of secondary drilling phases.
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About the Author: Hannah Peterson | hydroGEOPHYSICS
Hannah Peterson is a Staff Engineer and geophysicist for hydroGEOPHYSICS with a background in engineering, coding, and data analysis. She has broad field experience involving geophysical data processing, surveying, and geological interpretation in both land and marine settings. Her professional focus is on electromagnetics, electrical methods, data processing, and inversion.
Hannah holds a BS in Geophysical Engineering from the Colorado School of Mines and an MS in Earth Science from the University of California San Diego.
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