Rising groundwater threatens thousands of toxic sites in the Bay Area

As climate change brings devastating storms and rising tides to California, many coastal communities face another threat, one that’s hidden and trickling up from below.

When sea levels rise, dense saltwater moves inland beneath the soil, pushing up the layer of fresh groundwater that floats above it. In many coastal areas, even a few inches of sea level rise can raise the groundwater table enough to flood basements, leak through cracks in sewer lines and disrupt underground infrastructure.

It can also seep into toxic sites from below, mobilizing hazardous materials and spreading pollutants far beyond the limits of the original contamination.

A new report finds that over the next century, rising groundwater levels in the San Francisco Bay Area could impact twice as much land area as coastal flooding alone, putting more than 5,200 state- and federally-managed contaminated sites at risk. Many of these sites are near communities already burdened with high levels of pollution, including West Oakland, the waterfront in Richmond and Hunter’s Point in San Francisco.

“All of these sites need to be reevaluated because it’s not clear that people are safe, and with each passing year, there is more risk,” said study lead author Kristina Hill, associate professor of landscape architecture and environmental planning at the University of California, Berkeley. “We really need to reevaluate these sites in relation to rising groundwater because the remediation strategies and management plans didn’t consider […]

Full article: news.berkeley.edu