More than 10,000 pounds of sediment contaminated with polychlorinated biphenyls—PCBs—lies at the bottom of San Francisco Bay, much of it the legacy of factories that closed long ago. More PCBs are believed to wash into the bay as stormwater carries still-contaminated residue from around the region. The problem is severe enough to warrant a health advisory for eating fish caught in the bay—regularly eating sturgeon and striped bass from the bay can cause cancer, officials say. But removing the contamination is tricky; dredging it would likely stir up the sediment and create an even greater problem.
A $5 million grant from EPA will help identify ongoing sources of PCBs. The goal, according to the San Francisco Regional Water Quality Control Board, is to reduce the amount of PCBs reaching the bay by 95% over the next two decades. The first steps are to simply identify sites that need to be cleaned up. The grant will also help pay for devices to trap sediment from creeks and rivers that are conveying the most pollution to the bay.
Although much of the contamination came from industrial operations that have long since shut down—some even before the danger from PCBs was recognized—there is still plenty of PCB-containing equipment such as capacitors and transformers in use, as well as buildings still standing with components that include PCBs. When PCBs were banned in the late 1970s, EPA allowed closed systems containing the substances to continue operating, but the agency is now reconsidering that decision. In addition to the risk of leaks, one environmental scientist notes, “The end of life for this electrical equipment is often a fire, when you get a lightning strike or an overload in the system,” releasing quantities of fluids.
This article from the San Jose Mercury News details the problem and the work that will be carried out with the grant money.