More details about alternative methods for contaminated soil disposal

In the last column I described the alternatives that have been considered to dispose of contaminated soils and then explained whether those alternatives would meet cleanup goals. This column is a continuation of that discussion. Here I will discuss the following waste soil disposal options: phytoremediation, vitrification, making soil into concrete, and “Filling the Holes,” also known as a “Community Fill Policy (CFP).” I will also address a question that came up from the last column. Phytoremediation: Phytoremediation is a way to treat contaminated soil by using plants to absorb contaminants from the soil and then harvesting the plants and hauling them to an appropriate disposal location. One of the challenges with this approach is that few plants like to absorb lead or arsenic, and when they do, they don’t absorb very much. So it can take many growing seasons to reduce lead and arsenic levels to safe levels. Also, phytoremediation is difficult to do on a large scale because the contaminated soil is extremely widespread. For example, in the Lower Basin, over 28 square miles are contaminated; this ground would need to be seeded with lead and arsenic-loving plants. Growing these plants also may not fit with current land uses employed by landowners. For example, the plants needed for successful phytoremediation may not be a suitable replacement for grass crops such as alfalfa or grass hay, small grains, timber, or orchards. Vitrification: Vitrification permanently traps harmful chemicals in a solid block of glass-like material. The process uses electric power to melt the soil and trap the contaminants. Vitrification doesn’t make economic sense for large-scale applications that would be needed at this site. In-place vitrification results in a sterile, impermeable soil on which nothing can be grown and no water can infiltrate. The result would be ponded water in places where it never did before, increased runoff into storm drains, increased runoff water temperatures, potentially more polluted storm water without the filtering effects of vegetation, and more. At the yard-soil level, electrical currents coursing through the soil would pose a significant risk to the landowner’s water and sewer pipes, wells, fences and foundations. Vitrification is a risky choice for landowners and agencies. Make Soil into Concrete: Concrete is a blend of cement (powdered limestone), gravel and sand. The idea behind this approach would be to use the contaminated soil to help make concrete, turning a waste into a useable product. Including soil in a concrete mix would decrease the strength of the concrete, however, and make the concrete unsuitable for most typical uses. Fill in the Holes, a.k.a. Community Fill Policy: The “Fill in the Holes” or “Community Fill Policy” is an idea being worked on in response to requests from the community. Its purpose would be to allow moving contaminated soil from a borrow area on one person’s property to a low spot elsewhere in the Superfund site on someone else’s property. The Institutional Controls Program (ICP) regulates contaminant migration off properties and makes sure appropriate barriers are installed over contaminated soil. As this concept is further developed, it will be discussed at meetings with local officials and to share with the public via the Basin Commission process (Project Focus Teams). And, now to address another recent question … What is the life of a capped repository? How many years before it degrades and the contained waste begins leaching into the environment? Repositories are engineered to withstand the effects of floods, earthquakes, and erosion from wind and water. After a repository is filled to capacity, it will be capped with clean soil and re-vegetated. Repositories are monitored regularly, including water quality monitoring during their construction as well as after they are completely filled and capped. An Operations and Monitoring (O & M) Plan is created and implemented at the time of closure. The purpose of the plan is to monitor, inspect, and make repairs to avoid releases of contaminated materials back into the environment. Thus, the repositories will be inspected regularly, water quality will be monitored, and the repositories maintained as needed to prevent releases of contaminated soil and metals. Monitoring will continue for decades after filling is complete. In sum, repositories will not be allowed to degrade, and if a problem arose, repairs would be made to prevent releases into the environment. If you would like to be on the Bunker Hill Superfund site (Basin Bulletin) mailing list or email list to get updates, contact Andrea Lindsay at lindsay.andrea@epa.gov or 800-424-4372. I would also like to report that Denna Grangaard was recently hired by DEQ as a Community Involvement Coordinator in the Kellogg Superfund Office. She grew up in the Kellogg area and is very involved with the community. Denna looks forward to meeting with people and their groups to provide information about the projects happening at this Superfund site. She is located in the Kellogg Superfund Project Office, 1005 West McKinley, Kellogg, Idaho 83837. Contact her at denna.grangaard@deq.idaho.gov or 208-783-5781 if you have questions about the Superfund or if you would like to have staff from EPA/DEQ present information about projects at your next meeting.