By: Matt Lyter (Senior Staff Geologist at St-John-Mitterhauser & Associates, A Terracon Company) and Jim Depa (Senior Project Manager/3D Visualization Manager at St-John-Mitterhauser & Associates, A Terracon Company)
Three-dimensional (3D) modeling technology is used by geologists and engineers in the economic and infrastructure industries to help organize and visualize large amounts of data collected from fieldwork investigations. In the oil and gas industry, petroleum geologists use 3D models to visualize complex geologic features in the subsurface in order to find structural traps for oil and natural gas reserves. In the construction industry, engineers use 3D maps and models to help predict the mechanics of the soil and the strength of bedrock for construction projects. In the mining industry, economic geologists use high resolution 3D models to estimate the value of naturally occurring ore deposits, like gold, copper, and platinum, in a practice known as resource modeling.
All of the models are built in almost the same exact way: 1) By collecting and analyzing soil samples and/or rock cores; 2) Using a computer program to statistically analyze the resulting data to create hundreds or even thousands of new (or inferred) data points; and 3) Visualizing the actual and inferred data to create a detailed picture of the ground or subsurface in three dimensions. These models can be used in the economic and infrastructure industries to help predict the best locations to install an oil or gas well, predict the size of an oil or natural gas reserve, assist in the design of a road, tunnel, or landfill, calculate the amount of overburden material needing to be excavated, or help to predict the economic viability of a subsurface exploration project.
However, because of the significant amount of computing power needed to create the models, usage of the technology by regulatory driven industries has been limited. But continuing technological advancements have recently made 3D modeling technology more accessible and affordable for these regulatory driven industries, including the environmental investigation and remediation industry. Complex 3D models that previously may have taken several days to create using expensive high-end computers, can now be made in several hours (or even minutes) using the technology present in most commercially available desktops. Because of these advancements, subsurface contamination caused by chemical spills can be visualized and modeled in 3D by environmental geologists at a reasonable price and even in near real-time.
Some of the applications of 3D modeling technology in the environmental investigation and remediation industry are only just beginning to be utilized, but they have already helped to: 1) Identify data gaps from subsurface investigations, 2) Describe and depict the relationship between the geologic setting of a site and underground migration of a contaminant, and 3) Provide a more accurate estimate of the amount of contamination in the subsurface. The models have also helped contractors design more efficient remediation systems, assisted governmental regulators in decision making, and aided the legal industry by explaining complex geologic concepts to the non-scientific community. This is especially true when short animations are created using the models, which can show the data at multiple angles and perspectives – revealing complexities in the subsurface that static two-dimensional images never could.
The consultants at St. John-Mittelhauser and Associates, a Terracon Company (SMA), have used 3D modeling technology on dozens of sites across the United States, most recently, at a large-scale environmental remediation project in the Midwestern United States. Contamination from spills of trichloroethylene (TCE), a once widely used metal degreaser, were identified at a former auto parts manufacturer during a routine Phase 2 investigation. Dozens of soil samples were collected and analyzed in order to define the extent of contamination, and once completed, traditional 2D maps and a series of cross-sections were created. One of the cross sections is shown in the image below:
Traditional Cross-section Showing Geologic Units and Soil Sample Results
The maps and cross sections were presented to remediation contractors with the purpose of designing a remediation system precisely based on treating only the extent of the contaminated soil. The lowest bid received was for $4.2 million dollars (USD), however, it was evident to SMA that all of the proposed designs failed to take into account the complexity of the subsurface contamination. Specifically, large portions of the Site, which were not contaminated, were being proposed to be treated. Therefore, using a 3D dimensional modeling program, SMA visualized the soil sample locations, modeled the extent of the contaminated soil in 3D, and created an animation showing the model at multiple perspectives and angles, at a cost of $12,000 (USD). A screenshot of the model is provided below:
3D Side View of TCE Contamination in Soil (15 PPM in Green, 250 PPM in Orange)
The project was resubmitted to the remediation contractors with the 3D models and animation included, resulting in a guaranteed fixed-price bid of $3.1 million dollars – a cost savings of over $1.1 million dollars for the client. Additionally, an animation showing both the remedial design plan and confirmatory sampling plan was created and presented to the United States Environmental Protection Agency (the regulatory agency reviewing the project) and was approved without any modifications. To date, the remediation system has removed over 4,200 pounds of TCE from the subsurface and completion of the project is expected in 2019. A short animation of the 3D model can be viewed on YouTube.
The 3D modeling software has also been used to help determine the most cost-effective solution for other remediation projects, and has been able to identify (and clearly present) the sources of chemical spills. The following link is an animation showing three case studies involving spills of perchloroethene (a common industrial solvent) at a chemical storage facility, ink manufacturer, and former dry cleaner: https://www.youtube.com/watch?v=0IlN_TIXkGk.
The most cost-effective remediation option was different for each site and was based on the magnitude of the contamination, maximum depth of contaminated soil, geologic setting, and the 3D modeled extent of contamination. Specifically, the contamination at the chemical storage facility was treated using electrical resistance heating technology, chemical oxidants were used to treat the soils at the ink manufacturer, and soil vapor extraction technology was used at the dry cleaner.
However, several barriers remain which prevent the wide-spread use of 3D modeling technology. The various modeling programs can cost upwards of $20,000, as well as yearly fees for software maintenance. There are also costs to organize large datasets, build the necessary files, and create the models and animations. It also must be noted that the 3D models are only statistical predictions of site conditions based on the available data, and the accuracy of the models is wholly dependent on the quantity, and more importantly, the quality of the data. Even so, 3D modeling technology has proven to play an important role in the environmental remediation industry by helping project managers to understand their sites more thoroughly. It has also provided a way to disseminate large amounts information to contractors, regulators, and the general public. But, perhaps, most-importantly, it has saved money for clients.
About the Authors
Matt Lyter (Senior Staff Geologist at St-John-Mitterhauser & Associate, A Terracon Company) provides clients with a wide range of environmental consulting services (Environmental litigation support; acquisition and transaction support; site specific risk assessment, etc.), conventional and state-of-the-art environmental Investigation services, and traditional to advanced environmental remediation services.
Jim Depa (Senior Project Manager/3D Visualization Manager at St-John-Mitterhauser & Associate, A Terracon Company) has over 12 years of experience as a field geologist, project manager, and 3D modeler. He is well-versed with a variety of computer programs including: C-Tech’s Earth Volumetric Studio (EVS), Esri’s ArcGIS, AQTESOLV, MAROS, Power Director 16, and Earthsoft’s EQuIS