Kingston Ash Slide
Solids/Ash Testing Results
(Sampling performed December 2008, January 2009, and September 2009)
Testing of Kingston ash samples collected from the undisturbed storage cell and from the ash flow area in December 2008, January 2009 and September 2009 shows that concentrations of most metals in the ash are within the range of concentrations found in natural soils in Tennessee or background levels in soils in the local area.
Although ash is not soil, comparing the concentrations of metals in ash to concentrations of metals in soil helps put the results in a common perspective.
The human exposure pathway of this ash is limited. There are no U.S. standards for levels of these metals in soil, but the levels are consistent with what is commonly found in Tennessee soils. Exposure at these low levels is not expected to be a human health hazard. As recommended by the Tennessee Department of Health if you come into contact with ash, wash thoroughly, including your hands, clothes and shoes.
For decades, much effort has been spent nationwide to determine the concentrations of various trace elements in coal ash. It has been found that the levels of the various elements are highly dependent on the source of the coal that was burned and that the levels can be highly variable. The values presented here are not surprising nor out of expected ranges when compared to that nationwide body of information. Furthermore, other governmental bodies have also sampled the TVA ash and have found similar results to those presented here. TVA remains in contact with other governmental bodies to perform interagency comparisons of data and to ensure that potential public health hazards and environmental hazards are constantly being assessed.
The following describes the methods used to obtain this data. Links at the bottom of the page will connect you to the charts displaying the complete results.
Methods and Reason for Update
In March 2009, TVA posted to the website test results for ash samples taken on December 31, 2008 and January 6, 2009. The method initially used for sample preparation was one of two methods accepted by US EPA for solid materials. During the normal course of reviewing the analytical work, TVA’s quality assurance Contractor recommended that we switch to another accepted analytical method which would increase the accuracy of test results. The basis of the recommendation was an observation that a higher heat method of preparing samples (microwave technology) would assure that the solids (i.e., the earth and ash sample) were more thoroughly extracted into solution. Extraction and dissolution are important first steps in the analytical process to ensure that analytes present in the sample are released into solution in order to be measured. TVA accepted this recommendation and has rerun the analyses using the more rigorous method. It is these results that are now posted on the website.
In summary, with only one exception, the concentrations of most metals are somewhat higher in the reanalysis using the more rigorous sample preparation. This confirms that the recommendation to go to this other preparation method was a good one. Even though the concentrations are somewhat higher, they do not change the conclusions reached using the original results; these conclusions are restated in the summary section above.
Complete Ash Testing Results
The following graphs represent a visual summary of the levels of metals found in three series of ash samples that were collected and submitted for laboratory analysis since the December 22, 2008 release. Each page represents the results of all ash samples tested for that metal; for example the first page is a summary of arsenic levels, the second is a summary of beryllium levels, and so on to the last page which is a summary of the levels of zinc found in the ash samples.
For each graph, along the bottom on the horizontal axis, the symbols "AF", "GP" and "S" represent discrete sample names that correlate with the locations on the map provided. "AF” stands for samples from the "ash flow area" or released ash, the "S" samples were composite samples taken from the surface of the undisturbed cell area, and the "GP" series were vertical cores of the undisturbed cell taken with a Geoprobe ® device down to a depth of 60 feet below the surface.
The values on the left-side vertical axis represent the laboratory reported concentration in mg/kg, which is an expression of the metals concentration.
The black line drawn across various heights on each graph indicates the established concentration of that metal in typical Kingston background soils. The larger blue shaded area indicates the range of concentrations for that metal in typical Tennessee background soils.
The Kingston background soil levels for the various elements may differ from the range of concentrations for Tennessee soils because of the underlying geology specific to the Emory River basin. Trace elements vary widely in the surface soils of the state.
Four exceptions are noted. Measured concentrations for three arsenic, two selenium and ten vanadium samples are slightly higher than the range found in Tennessee soil. Also, the Tennessee background soil range for beryllium referenced by TDEC (0.5 to 1.0 mg/kg) is less than the established background level for the local area (2.2 mg/kg). Although this appears odd, another reference states a range of 1.5 to 15.0 mg/kg from the nearby Citico Creek Wilderness Area in Monroe County, Tennessee. Based on this additional reference, the beryllium concentrations observed in the TVA ash, (which do not exceed 10 mg/kg) are consistent with background levels of beryllium in local soil.
The levels of cadmium, chromium, copper, lead, mercury, nickel, silver, thallium and zinc in the majority of TVA ash samples were found to be within the range for soils found throughout Tennessee.
The first map shows the sampling locations for the GP, S and AFA samples taken at the end of December 2008 and in early January 2009. The second map shows the sampling locations for a set coded “EECA” which was a re-sampling event designed to measure mercury in the intact cell and in the ash flow area.