Development of Non-Collinear Arrays for Use Near Wastewater Holding Ponds

Mineral and organic salts from beef manure contained in precipitation runoff from feedlot pen surfaces can alter the conductivity properties of soil and water receiving it. Typically, holding ponds are constructed to control runoff from concentrated animal feeding operations. The integrity of these holding ponds has come under increased scrutiny since subsurface leakage has the potential to affect soil and groundwater quality. Traditionally, ponds are monitored by installing monitoring wells at strategic locations to evaluate the impact of these ponds on the environment. Monitoring wells are expensive to install, costly to sample and the information received is subject to ambiguous interpretation. Researchers from USDA-ARS U.S. Meat Animal Research Center have combined efforts and resources with the Nebraska Cattlemen, the Nebraska Department of Environmental Quality (NDEQ), and AgraTek LLC, to evaluate electronic monitoring of subsurface soils near holding ponds used to contain runoff from beef cattle feedlots. A three year study summarized data from two feedlots and concluded that resistivity array systems were able to adequately measure subsurface dynamics and to alert operators of changes that exceeded nominal operation. Subsequently, two NDEQ provisionally approved systems were installed at a University of Nebraska research site. Unlike previous test installations, each of these new sites required non-collinear installations. This report discusses the theoretical development and testing of non-collinear arrays which proved to be a viable approach to unique array geometries necessitated by feedlot designs.