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This project was performed to determine the environmental and engineering performance of coal combustion fly ash in soil stabilization in Minnesota. The Energy & Environmental Research Center research was part of a larger effort performed by several industrial entities in response to questions raised about the use of fly ash in soil stabilization by the Minnesota Pollution Control Agency.
Objective
To evaluate the potential release of inorganic constituents, including mercury and arsenic, into the environment from coal fly ash-soil stabilization.
Methodologies
Industrial partners chose 11 commercial sites to demonstrate the environmental and engineering performance of regionally available coal fly ash in soil stabilization. Application rates were 12 or 14 parts fly ash added to 100 parts soil. For each site, the following was conducted:
| • | Samples were collected including a background soil sample, an ash sample, a background water sample (where needed), and fly ash-stabilized soil core samples. |
| • | The raw materials were analyzed for trace element composition. |
| • | Stabilized soil core composites were subjected to U.S. Environmental Protection Agency Method 1312 (SPLP [synthetic acid precipitation leaching procedure]), American Society for Testing and Materials D3987, and long-term leaching tests at the EERC. |
A simulated rainfall demonstration was conducted at the University of Minnesota-Rosemount Research and Outreach Center as a runoff evaluation of fly ash-stabilized soil, lime-stabilized soil, and untreated soil. The work was performed by Dr. Paul Bloom and Hero Gollany of the University of Minnesota Department of Soil, Water, and Climate.
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Simulated rainfall
runoff results (left to right): Control (soil), fly ash-stabilized
soil, lime-stabilized soil. The fly ash-stabilized soil runoff has
the least amount of sediment.
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Construction of fly
ash-stabilized road (photo courtesy of Lafarge North America).
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Included in the report is an existing study conducted by Environmental Toxicity Control, Inc., evaluating the relative toxicity of soil, soil-lime, and soil-fly ash leachates.
Results
Laboratory leaching and field runoff sampling indicated that the fly ash constituents exhibited only limited mobility. Overall, this study confirms the outcomes of other similar studies that fly ash, if used properly, is an environmentally sound option with economic and engineering advantages.
Reports
Contacts
| David Hassett
Senior Research Advisor (701) 777-5192 dhassett@undeerc.org |
Loreal Heebink
Research Chemist (701) 777-5116 lheebink@undeerc.org |
Project Partners
| • | EPRI |
| • | Lafarge North America |
| • | University of Minnesota Department of Soil, Water, and Climate |
| • | U.S. Department of Energy National Energy Technology Laboratory |
| • | Xcel Energy |