About this project
This project was a collaboration of the Research Translation Core of the UNC Superfund Research Program (UNC SRP) and the North Carolina Division of Public Health (NC DPH). The purpose of this project was to develop the capacity of NC DPH to identify North Carolina populations at greatest potential risk from well water contamination and enhance the public’s understanding of environmental exposures, distribution of contamination, and the impact of groundwater on human health.
This project was funded by an ARRA-supplement to the Research Translation Core of the UNC Superfund Research Program. The national Superfund Research Program is a university-based program within the National Institute of Environmental Health Sciences (NIEHS), a branch of the National Institutes of Health (NIH).
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Data used in this project
The data used in this project were all private well tests received by the NC State Laboratory of Public Health from 1998-2010. Investigators used these data to map the concentration of 31 contaminants, many of which are also Superfund priority chemicals. The maps represent the average concentration of contaminants detected in each county as well as National Priority List sites and facilities that reported to the US Environmental Protection Agency (US EPA) Toxics Release Inventory. US EPA data were included to increase public awareness of hazardous wastes sites and other sources of toxic releases throughout the state.
Maps developed in this project
All maps created from this project represent the average concentration of contaminants detected in private well water samples in North Carolina counties. Two maps are available for each contaminant: one map represents the average of all data from 1998-2010, the second map reports the average of all well samples collected in the year 2010.
In addition, advanced mapping and geocoding techniques were used to characterize two contaminants- arsenic and perchloroethylene (PCE). Researchers in this project applied a Bayesian Maximum Entropy (BME) framework to predict the concentrations of these two contaminants in unmonitored locations and to characterize spatiotemporal changes in the distribution of these contaminants.
Features of the county-level maps
The maps from this project contain information about the average concentration of each contaminant detected in private well water for all 100 counties of North Carolina as well as information about National Priorities List sites and facilities reporting to the US Environmental Protection Agency (US EPA) Toxics Release Inventory.
County-level averages reported on maps
The maps that appear on this website depict the county-level average of 31 contaminants tested in North Carolina. County-level maps were used for this project because they provide a quick and easy-to-understand visual of the possible patterns in the distribution of well water contaminants throughout the state. The color of the county on the map corresponds to various concentration levels in the map legend.
National Priorities List sites on county-level maps
The National Priorities List (NPL) is a federal registry of contaminated sites throughout the United States. NPL sites are identified as part of the US Environmental Protection Agency’s (US EPA) Superfund program, a federal program to clean up the nation’s uncontrolled hazardous waste sites. There are 1,305 NPL sites in the United States; 39 NPL sites are located in the state of North Carolina (2013).
NPL sites were added to the project maps to indicate known hazardous releases of certain chemicals. NPL sites are indicated by a triangle on the project maps. All data for NPL sites were collected from publically-available information from the US EPA; more information about NPL sites in North Carolina can be found here.
Toxics Release Inventory releases on county-level maps
The US EPA Toxics Release Inventory (TRI) is a database containing information on the disposal or other releases of more than 650 toxic chemicals from facilities throughout the United States. Regulated facilities must report releases and transfers of toxic chemicals and make the data available to the public through the TRI.
TRI data were added to the project maps to illustrate possible sources of contamination while also depicting the average concentration of contaminants detected in private wells. TRI data were reported on the North Carolina maps using graduated circles. The size of the circle is proportionate to the magnitude of the release- the larger the release from the facility, the larger the circle on the map. The circles are based upon the average release of the contaminant from each facility. All data in the TRI are self-reported by the facility.
How to interpret TRI data on the map
TRI data on the North Carolina maps include reported releases for a specific contaminant but do not reflect the overall releases of all chemicals at that facility, nor does the presence of size of the toxics release reflect the regulatory or legal status of the facility. Reporting in the Toxics Release Inventory does not mean that an uncontrolled release occurred or that the quantity of the chemical present at a site poses a risk to human or environment health.
Below is an example of TRI reporting for a contaminant in North Carolina. In this example the facilities that reported to the TRI appear densely clustered in a single location. Zooming in on the map helps to show that there are numerous facilities within the region that reported a release of a specific contaminant to the TRI.
Some maps do not include TRI data because the contaminant is not listed in the US EPA database or there are no reported releases of the contaminant in North Carolina. Toxics Release Inventory data represented on website maps were obtained from the US EPA TRI database for the years 1998-2009. All data are reported in pounds (lbs.) and are based upon the average annual release. The average release was determined by calculating the sum of all annual releases at a particular facility (reported in column CE of the TRI) divided by the number of years for which there was a reported release. Not all facilities reported a release each year.
Calculations used for county-level maps
The county-level maps depict the average concentration of a contaminant in each county. The average was calculated by adding all of the well-testing results for a particular contaminant in each county and dividing the sum for each county by the number of samples collected in that county. View the county statistics to find out the number of wells tested in each county as well as the minimum, maximum, and average concentration of each contaminant.
The county-level averages reported for each contaminant are based on private well tests from the North Carolina State Laboratory of Public Health from 1998-2010. A county-level map is also available for all well-testing results received during the year 2010.
In addition to the average concentration of each contaminant, the county-level maps include National Priorities List sites in which the specific contaminant has been detected and regulated facilities that have reported transport or release of the specific contaminant in the Toxics Release Inventory.
Techniques used for advanced TrAC maps
The TrAC project also utilized advanced mapping and geospatial techniques to generate maps of tetrachloroethylene (PCE) and arsenic contamination in North Carolina. Using the Bayesian Maximum Entropy (BME) framework, Land Use Regression modeling, and Geographic Information Systems (GIS), the maps provide spatiotemporal predictions of the concentration of contaminants in groundwater. More information about BME analysis and projects can be found at The University of North Carolina at Chapel Hill’s BME Lab website.
- View information about a study of arsenic in North Carolina groundwater that uses advanced spatial mapping techniques.
- View a moving map of tetrachloroethylene (PCE) in North Carolina groundwater that uses advanced spatial mapping techniques.
If you are using or presenting maps or materials from this website, please cite this project: UNC Superfund Research Program- Research Translation Core, ARRA supplement from NIEHS (P42-ES005948) 2009-2011.
This project was funded by an ARRA supplement from the National Institute of Environmental Health Sciences (#P42ES005948) 2009-2011.