The spread of a PCB spill on a soil surface

Determining the fate of an oil spill on soil is often the first step in analyzing the risks of human exposure to hazardous viscous liquids such as PCBs. The special surface properties of rigidity and porosity are not among the boundary conditions in previous analyses of spills on water. The present work solves the expressions of mass and momentum conservation using a perturbation approach. Using the example of an Aroclor 1254 spill to illustrate the approach, we find that the radius at the halt of spreading is roughly proportional to spill volume for large spills. Spreading halts when the infiltration equals the spill volume. The radial distribution of infiltration decreases gradually from its central maximum, but falls suddenly to zero approaching the outer edge. Sample results are plotted for Aroclor 1254 spills from 4 to 21 liters in volume.