Construction of Large-Scale Research Plots at a Remediation Site Using Thermal Desorption.

Ex situ thermal desorption (TD) is a remediation technique that could be especially useful for treating contaminated agricultural soils because it returns the soil for reuse in a shorter timeframe than many other techniques.  In an effort to better assess plant growth and changes in soil properties in the field, large-scale plots are oftentimes needed. However, construction of plots and uniformity can be problematic.  The objective of this research is to outline the construction of field-based plots used to assess the plant production and evolution of soil heath forming factors over several growing seasons on TD-treated soils.  This research takes place on plots constructed adjacent to an active TD remediation site in Mountrail County, North Dakota.  The 30 plots (17m x 15m x 0.9m) are comprised of 5 treatments: 1) Native, non-contaminated topsoil; 2) TD treated soil; 3) 1:1 mixture of native topsoil and TD treated soil; 4) Untreated, contaminated soil; 5) 1:1 mixture of native topsoil and untreated, contaminated soil.  Plots were constructed using large-scale equipment to precisely place treatments into respective positions. Plots were sampled for uniformity in chemical, physical, and biological properties. These large-scale research plots will offer valuable information about the immediate effects of TD on agricultural production, as well as the opportunity to evaluate how TD treated soils respond to field conditions over the course of several growing seasons.  Further, this research will document the degradation of petroleum products in the soil, as well as any uptake into plant structures and may guide recommendations for remediation of petroleum product releases that will be beneficial to farmers, ranchers, environmental industries, and state regulatory agencies.