Show and tell

In the United States, the growth and use of computer models have resulted from a number of strict comprehensive environmental statutes first initiated in the early 1970s. As personal computers and software became more user-friendly and less costly, computer models for predicting and illustrating environmental conditions became more prolific.

The most important environmental statutes that require some type of modeling include the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA, also known as Superfund), the Resource Conservation and Recovery Act (RCRA), the Safe Drinking Water Act (SDWA) and the National Environmental Policy Act (NEPA). Additionally, the use of computer modeling coupled with three-dimensional (3-D) visualization has been driven by attorneys' and environmental experts' desires to communicate complex environmental conditions to a lay audience (usually a jury). Although these visual models were developed for purposes of litigation, other applications include demonstrations to regulatory agencies, insurance companies or other less technical audiences, where visualization can provide an effective means of explaining complex site conditions.

System representatives

In terms of the environmental profession, a model refers to the representation of any real system. A system's representation can include illustrations of surface and subsurface conditions using geostatistics, as well as the simulation of water, sediment and air transport through such a system. For the purpose of this article, the models referenced represent the subsurface and surface conditions, excluding the simulation of air, surface water or groundwater movement in or around them.

Geostatistical modeling to produce 3-D graphical animations was recently used to support the expert testimony for the plaintiff in a case arising from manufactured gas waste contamination. The case was tried in 1999 in federal court in the U.S. District Court. In City of Newburgh, New York v. Central Hudson Gas & Electric Corporation, 95 Civ. 3863, First Environment Inc. used the Mining Visualization System (MVS) geostatistical software developed by C Tech Development Corp. to visualize the site surface and subsurface conditions at a former manufactured gas plant (MGP) project area in Newburgh, New York, adjacent to the Hudson River.

The intended use of the MVS was to reflect the shoreline history as well as the geology and coal tar contamination identified at 158 soil borings. This information was used to illustrate and explain the migration and accumulation of coal tar contamination related to the former MGP in three separate plumes. This data was translated into three distinct models that included the historic shoreline and subsurface conditions. Once each model was created, it was used to produce a dynamic computer-driven animation that told a story that could be easily understood, providing a clear and accurate basis for the expert's testimony to the jury that ultimately helped the plaintiff's attorneys assemble a winning case.

Model creation

The MVS software runs under Windows™ 95/98/NT and unites state-of-the-art analysis and visualization tools into an extremely powerful software system developed primarily for geologists, geochemists, engineers and modelers. The graphical user interface is integrated with modular analysis and graphics routines that are then customized by the scientist (user) and combined to satisfy the analysis and visualization needs of any application.

MVS software unites interpolation, geostatistical analysis and fully 3-D visualization tools into a software system developed to address mining and environmental contamination issues. The software can be used to analyze all types of analytes and geophysical data in any environment (e.g. soil, groundwater, surface water, air, etc.). One of its greatest strengths is the integrated geostatistics that provides quantitative assessment of the quality of a site assessment (min-max plume technology) and identification of locations in a site which require additional investigation. MVS's tools can improve site assessment and enhance the capability to analyze and present data for assessments, remediation planning, litigation support, regulatory reporting and public relations.

MVS, a stand-alone program that does not require any additional software, can perform 3-D post-processing and animation for groundwater and solute transport modeling packages such as MODFLOW and MT3D.

They can read and write AutoCAD DXF files, ESRI shapefiles, and can directly access ODBC compliant databases (provided ODBC 32 is installed on the clients' computer). Environmental database and data management software products such as ESRI's ArcView GIS, Integrate's TerraBase, EarthSoft's EQuIS and GIS Solution's GIS/Key are also supported.

Animation creation

The geologic modeling occurred in two stages. The first step required an expert geologist to determine the geologic hierarchy of the site using numerous hand-drawn two-dimensional cross-sections that honored the site boring log data. Then the geologic layer bottom elevations (for each borehole) were transferred to an electronic input file for 3-D geologic model creation in MVS. Since this job was completed, enhancements to MVS could make it possible to eliminate the hand-drawn cross-sections and manual interpretation of the site geology.

Many different animations were generated from the resulting shoreline and subsurface models, of which two primary animations were used during the court case. The Animator module found in MVS makes this process very simple, providing powerful capabilities to simultaneously modify the parameters of many modules in an application for each frame of the animation. The Animator creates a journal file that automates the adjustments of module parameters and simultaneously creates a sequence of image files. This string of images can then be converted to on-screen animations using video creation and editing software.

Once the computer animations of the 3-D visualizations were created, the animation files were coded for user-friendly access in the courtroom setting via bar code technology. Bar codes were created for every action necessary to display the animations in an interactive setting. To this end, the expert witness was able to perform numerous interactive tasks with the computer animations, such as playing and stopping an animation, stopping at pre-specified frames, playing in reverse, etc. Each action had a bar code strip with a bold faced description of "what would happen" upon swiping the bar code. The user was able to operate the computer without ever having to touch the keyboard (or mouse) and did not have to understand the operations of the computer software or hardware. Bar code technology made the task of interactively controlling the suite of animations and images as easy as checking out at the grocery store.

Depending on the complexity of the site conditions, the amount of the data and the sophistication and quality of the final product, the cost to produce a model and animate it can range from a few thousand dollars to more than $100,000.

Case study

The total site area is approximately 12 acres and is comprised of city property (streets, a wastewater treatment plant and underwater lands in the Hudson River), a railroad right-of-way currently owned by CSX and the former MGP. The former MGP and the CSX property occupy approximately 4 acres. The city property, located downgradient from the MGP, occupies the remaining 8 acres.

The models were used to produce animation to visually demonstrate the former landscape, the complex geology, the coal tar migration pathways and the complex distribution of coal tar found in the subsurface at the project area. Each animation was used to visually demonstrate one or more specific technical points during the expert's testimony.

Shoreline animation

The shoreline model was created to illustrate the historic deposition of land downgradient of the former MGP. The model was created from existing boring data and historic photographs, as well as National Oceanic Atmospheric Administration (NOAA), United States Geological Service (USGS), Sanborn and city engineering maps.

The purpose of this model and animation was to illustrate to the court and jury how the depth, extent and configuration of fill changed during the evolution of the shoreline from 1865 to 1998.

The animation from which these four frames were extracted can be viewed at www.firstenvironment.com/assets/videos/shore.ram.

This model (and corresponding animations and images) was crucial to the case. The utility that owned the former MGP contended that the coal tar contamination was either transported to the city's property and deposited in the fill material from elsewhere or the result of petroleum releases related to historic industrial activities located at the city property. The illustrations provided strong evidence to the contrary, showing that the coal tar below the fill had migrated there via naturally-deposited high permeability layers.

The animation also visually demonstrated the horizontal and vertical growth of the shoreline over time relative to the naturally deposited layers containing coal tar. The animation was able to illustrate to the jury that coal tar was not deposited in the fill or a release at the surface that migrated vertically, but rather migrated below the fill via contiguous natural pathways (channels) that connected to the former MGP.

This animation can be viewed at www.firstenvironment.com/assets/videos/dnapl.ram.

Subsurface animation

The purpose of the subsurface models was to illustrate to the court and jury the complexity of the 3-D geologic layering, the location of former sewers, the distribution of coal tar in those permeable layers and how those layers connected the former MGP to the downgradient city property.

To demonstrate the geology and distribution of coal tar, many geologic cross sections were manually constructed using the geologic data from 158 soil borings. In total, 13 geologic layers were identified for each boring across the site. In order to construct the subsurface model for purposes of animation, an electronic database was built that contained location and surface elevation for 158 borings and layer elevations and thicknesses for each. This database was used to build a site-wide 3-D geologic model. The site lithology was presented with four-color divisions.

  • Light brown/yellow — high permeability soils such as sands, gravels, silty sands, etc.
  • Dark brown — low permeability soils such as silts, clays, sandy clays, etc.
  • Turquoise — fill material (man-made deposition)
  • Gray — bedrock

This animation can be viewed at www.firstenvironment.com/assets/videos/geology.ram.

The subsurface model allowed geologists to evaluate detailed migration pathways from the former MGP to the city property at hundreds of different directions and depths. As a result, three migration pathways were discovered and confirmed by the occurrence of coal tar in three separate plumes. These areas showed the highest concentrations of coal tar and were considered the primary migration pathways of coal tar from the former MGP. These results were then recorded into the model 3-D animation for the court. The results helped the court and the jury visualize the complex geology and coal tar distribution as an animation that showed the unique layers, historic sewer pipelines and complex and tortuous migration paths through the sand and gravel layers that were interfingered with low permeable clay and silt layers.

The model helped the city's attorneys clearly define three source areas at the former MGP property. The power of this visual aid helped the court understand the MGP coal tar source areas, the complex migration of coal tar in the subsurface and to the Hudson River and its relationship to fill, sewer pipelines and the natural geologic conditions.

This animation can be viewed at www.firstenvironment.com.

Conclusions

The computer model and its animations were used successfully to illustrate and explain the migration and accumulation of coal tar contamination, related to the former MGP, in three separate plumes.

Once each model was created, it was used to produce a dynamic computer-driven animation that told a story that was easily understood. The animations provided a clear and accurate basis for the expert's testimony to the jury that ultimately helped the city's attorneys put together a winning case. As a result, the federal jury ruled the utility is responsible for $16 million in clean up costs. Remediation alternatives for the clean up of the coal tar contamination at the project area are currently being studied under a New York State Department of Conservation consent order.

Note: ArcView is a registered trademark of Environmental Systems Research Institute. Illustration courtesy of First Environment Inc. This article appeared in Environmental Protection magazine, Vol 11, No. 4, p. 50, April 2000.

This article originally appeared in the 04/01/2000 issue of Environmental Protection.

comments powered by Disqus