Phreatic flow on sloping soil layers from a finite source: An analytical solution

摘要

Sloping clay layers beneath percolation ponds can cause infiltrating wastewater to pond and move in directions not predicted by vertical infiltration equations. This report presents a method for estimating the potential of wastewater from percolation sumps located over sloping clay layers to interact with nearby groundwater resources. The analytical solution developed is for steady-state conditions and includes a procedure to estimate the time needed to reach steady state. The fundamental assumption used in the mathematical development requires that elevation-head gradients be much larger than pressure-head gradients. A method for testing the validity of this assumption is also included. An example calculation was performed for percolation sumps on the Naval Petroleum Reserve No. 1 in Elk Hills, California. That analysis showed that, under the assumptions used, the sumps may have enabled oil field wastewater to reach groundwater resources within the adjacent San Joaquin Valley. 9 refs., 10 figs.