Variable-density flow and transport modeling to evaluate anomalous nitrate concentrations and pressures in GW-134

The U.S. Department of Energy operates the Oak Ridge Reservation near Oak Ridge, Tennessee. Four waste disposal ponds, referred to as the S-3 ponds, were located within this reservation near the western edge of the Y-12 Plant. The S-3 ponds were constructed in 1951 and received liquid waste until 1983. The main component of the waste received by the ponds was nitric acid. In 1988, the ponds were structurally stabilized and capped and the area above the ponds was converted into an asphalt parking lot. Coreholes were drilled in 1985 to characterize the geology of the region. These coreholes have since been equipped with monitoring equipment capable of performing pressure measurements and collecting fluid samples. A modeling study was also conducted to evaluate scenarios potentially capable of producing anomalous pressure and concentration data observed in GW-134. Results are described