Waterproofing Waste

The aerial photo shows that Sunshine Canyon (CA) had three seasonal creeks that converged where the landfill now locates. To correct possible flooding of the landfill, Browning-Ferris Industries Inc. engineers adopted the following strategy for contending with the water flow: Slow it, divert it from the landfill, strip it of its silt, then allow it to continue onward.

To slow the water, BFI, which operates the landfill, built a dam at the bottom of each creek. The dams divert the water into a concrete-lined storm channel, which surrounds the landfill. The channel sends the water to a collection basin. Following silt deposition in the basin, the water slowly releases to its natural drainage of county storm channels. (State requirements call for the water's being returned at a rate no greater than if the landfill did not exist.)

Despite these precautions, some water reaches the landfill and percolates through the waste to become leachate. BFI, as does many another landfill operator, treats the leachate. The landfill operator then stores the treated leachate for irrigation use and for dampening dusty roads to reduce air pollution.

BFI believes the landfill is prepared for the heavy rains expected from El Niño. A district vice president/project engineer for BFI says that he has five engineers on staff to meet unforeseen challenges and that a county inspector also is constantly at hand. "We've built this thing of dirt, but there's a lot of quality control and engineering that goes into this dirt," he said.

The previous case study is adapted from a report by Steve Hymon, Los Angeles Times staff writer, which appeared in the newspaper's January 10 edition.