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An Ecological Framework to Evaluate Impacts of E&P Releases
Project Number

The goal is to develop a general framework within which ecological risk assessments can be conducted at an ecosystem or ecoregion scale. The specific purpose of this research is to investigate the role of size and spatial distribution of small impacted or contaminated sites to the larger ecosystem or ecoregion.

This project was funded through DOE's Natural Gas and Oil Technology Partnership Program. The program establishes alliances that combine the resources and experience of the Nation's petroleum industry with the capabilities of the national laboratories to expedite research, development, and demonstration of advanced technologies for improved natural gas and oil recovery.


Lawrence Livermore National Laboratory (LLNL)
Livermore, CA

Oak Ridge National Laboratory (ORNL)
Oak Ridge, TN


In the past decade, concern has increased over the environmental impacts of contaminants on ecological receptors. State and Federal agencies are increasingly requiring ERAs to estimate such impacts. These ERAs can be complex, relying on overly conservative assumptions to extrapolate laboratory toxicity data to field sites, and often consider areas that are too small to be ecologically relevant. Through the operation of upland exploration and production (E&P) sites, the petroleum industry has thousands of sites that may be impacted by the release of petroleum-related products (primarily petroleum compounds and brine fields) to various degrees. Many of these sites also will undergo closure in the near future. Due to their remote location, it is possible that ecological receptors, not human health, will drive the risk at these sites. Conducting traditional ERAs and any subsequent cleanup/site restoration could be quite costly industry-wide. These costs would be particularly burdensome to small, independent operators that typically do not have substantial resources. And such efforts actually may be unnecessary, as many areas impacted by petroleum-related products within E&P sites are small and localized within the context of a larger site. Conducting ecotoxicolgically-based ERAs at each of these isolated, impacted areas may provide a misleading estimate of the true impact on populations and communities at larger, more ecologically meaningful scales. This project was concurrent with FEW0054 at LLNL and ORNL.

Project Results
In this project, models have been implemented using an object-oriented programming structure. The structure of the template model consists of a hierarchical set of classes, with each class containing a number of objects. Within the ecosystem class (which keeps track of the initial conditions and climatic variables) is a species class and a landscape class. The landscape class contains a basic landscape disturbance grid upon which the species class will interact. Simulations that include prescribed burning and grazing occur on the background of a dynamic landscape. Map layers in the geographic information system (GIS) serve as landscapes for the model.

ORNL also has developed two stochastic models to describe the spatial distribution of brine spills. The first model attempts to produce spills based on typical well configurations. The second model is a simple statistical model that produces a specified spatial distribution of spills. ORNL is currently running simulations of the population model using the spill generator models.

The results of this research are intended to support PERF (Petroleum Environmental Research Forum) 99-01 in developing a protocol for conducting ecological risk assessments at the ecosystem or ecoregion scale and to develop criteria for the consideration of size of impacted sites in ecological risk assessments. In addition, the project will further enhance the capabilities of LLNL and ORNL through the expansion of shared and cross-platform GIS services, which may be of future benefit to DOE.

The project will reduce the necessity of performing Ecological Risk Assessments (ERAs) at small, remote sites; significantly decrease the cost of ecological evaluations; and eliminate unnecessary site cleanup and restoration. 

Project Summary
The TGPP in northern Oklahoma was selected as a representative E&P facility. An evaluation of the vegetation biomes of existing E&P facilities showed various grassland prairies and savannas to represent a significant percentage (>40% grassland, >7% tallgrass prairie) of these sites. The development of a protocol for the creation and data population of a GIS for E&P sites was successfully completed. This protocol will greatly facilitate the creation of a cost-effective GIS specifically for evaluating ecological impacts at E&P sites. Layers developed for GIS include Digital Ortho Quarter Quad photos, National Landscape Characterization (NALC) data (NALC, Landsat multispectral scanner), Normalized Difference Vegetation Index developed from NALC data, well locations, soil survey, AVIRIS (Airborne Visible/Infrared Imaging Spectrometer) hyperspectral flight lines, low-resolution vegetation, prescribed burn history, bison pastures, and land ownership.

The results of the review of available population models, the fragmentation, patch size, and home-range literature suggest that size criteria will be constrained by the general context of the facility and by the general type of endpoint species present. Additional onsite global positioning satellite data were collected for well location, well pad area, and brine and oil spill locations and size under FEW0054. ORNL completed the calculation of the preliminary site statistics using the GIS developed for the TGPP in Oklahoma. The site statistics calculated include total reserve area, pasture data (numbers, sizes, fencing lengths), length of and area covered by roads, length of streams, number and area of wells, burn rate, brine spill number and area, and vegetation coverage (woodland, savanna, prairie, pasture, crop, and other). These data will be used to support the modeling effort.

LLNL and ORNL completed the a simulation model to evaluate the effect of size and distribution of spills and habitat patches on ecological populations at the TGPP. The goal was to develop a generic, or template, model that could be used to determine frequency, size, and distribution of spills that would lead to a density of herbivores and/or predators that can be sustained. In addition, these spatially explicit models could be used to quantify how the effects of petroleum-related habitat loss differs for species with different life history attributes, mobility, and spatial habitat requirements.

LLNL has developed an individual-based model for simulating territorial species and their relationship to the spatial environment (herbivore-resource relationship) and to predators. The first implementation of the model describes the birth, death, aging, feeding, and movements of individual prairie voles on a spatial grid consisting of cells roughly corresponding to the home range of the vole and containing vegetation that changes in mass due to production and herbivory. Simulations have been performed to investigate the influence of overall habitat size and the patchy removal of habitat (habitat fragmentation at a scale similar to that experienced by E&P activities) on vole distribution and persistence. Preliminary results show a positive correlation between the overall size of the habitat and vole persistence. Fragmentation appears to have a positive influence on prairie vole distribution and persistence by delaying the time to overgrazing. A summary of the literature on the life-history attributes of the short-eared owl (a predator of the prairie vole) is near completion. This information will be used in the near future to develop a predator-prey simulation of short-eared owl-vole dynamics.

ORNL has focused on the development of a population model that uses a habitat suitability index as the basis for representing spatial variation in habitat. The population model recognizes six activities that individuals engage in during their lives: pre-breeding, mating, post-mating, birthing, rearing offspring, and dispersal. The model has been parameterized for the American badger and will be generalized in the future to represent other species of prairie birds and mammals. ORNL has created a generic landscape module to simulate vegetation transitions due to burning and grazing, and LLNL has created a vegetation growth module for use in the template model and created a basic vegetation grid from the GIS vegetation layer.

Current Status

The project is complete. This was a joint partnership project with ORNL under FEAC321.

Wildflowers blooming in the Tallgrass Prairie Preserve in northern Oklahoma. Photo by Harvey Payne, Director, Tallgrass Prairie Preserve.
Wildflowers blooming in the Tallgrass Prairie Preserve in northern Oklahoma. Photo by Harvey Payne, Director, Tallgrass Prairie Preserve.


Project Start
Project End
DOE Contribution


Performer Contribution


Other Government Organizations Involved
Oak Ridge National Laboratory

Contact Information

NETL - Jesse Garcia ( or 918-699-2036)
LLNL - Tina Carlsen ( or 925-422-7103)