Near Coasts, Rising Seas Could Also Push Up Long-Buried Toxic Contamination
Along some coastlines toxic contamination could seep into basements or broken sewage lines in coming years. In California's Bay Area, regulators are grappling with how to protect people.
Marquita Price grew up spending lots of time at her grandmother's one-story lavender house in Deep East Oakland. It's a place she's always considered home, and where her grandmother still lives. So Price, an urban planner, was upset to learn about a lesser-known aspect of climate change fueled by sea level rise: it could cause the groundwater beneath this formerly-industrial community to rise, and wreak slow-motion havoc in the process.
"How is that going to affect my family?" Price thought. "And my community and the assets that we worked so hard to hold?"
For many Bay Area residents who live near the water's edge, little-publicized research indicates groundwater rising beneath their feet could start to manifest in 10-15 years, particularly in low-lying communities like Oakland. And that could resurface toxic substances that have lingered for years underground.
"Everything human beings use, they spill," says Kristina Hill, an associate professor at UC Berkeley's College of Environmental Design, who researches adapting urban areas and shoreline communities to climate change. The overflow includes "everything we've used in the last hundred and fifty years."
That's a lot of things in the Bay Area, which is rife with industrial sites new and old. In East Oakland, industry boomed in the early 1900s as lumber yards, canneries, rail depots and foundries sprung up. It was a long time before governments enacted major environmental regulations, starting in the 1960s. "Through the entire postwar and World War II-era, stuff got dumped informally," Hill says.
More recent contaminants lie buried as well, chemicals like benzene and toluene, leaked from underground storage tanks. Many toxic sites now considered to be contained could pose a threat as the water ascends.
"Legacy contamination in the soil will be remobilized when the water table comes up and intersects with these areas of contaminated soil," Hill says. If the groundwater flows into contaminants no longer monitored because they are considered contained, those toxic substances may start to move unnoticed.
That contaminated groundwater could seep into a basement or crawlspace beneath a home, or sneak in through a broken sewage line. Some of these chemicals vaporize, so humans could breathe them in.
A recent report by Silvestrum Climate Associates, a private environmental consulting firm, found this could affect communities with a mile of the Bay Area coast. Hill and her colleagues have analyzed data and found the water below someone's backyard is typically within 6 feet of the surface of the ground, and often just 1-2 feet below the surface.
"It's possible that you have contamination in that water and you might not see it or smell it. You might not know," says Alec Naugle, who heads the toxics cleanup division for the San Francisco Bay Regional Water Quality Control Board. The agency regulates the mitigation of contaminated sites in a large area stretching over the nine Bay Area counties.
"If you're exposed to these chemicals over a lifetime, they can increase your risk of cancer," Naugle says. "Some of those chemicals also have short-term risks at much higher concentrations that we don't typically see in the environment."
Many neighborhoods most at risk have large Black and Latino populations who already deal with unequal environmental health burdens due to living near major freeways and, in Oakland, a sizeable port. Residents of East and West Oakland have high rates of asthma, and children in East Oakland are more than twice as likely to suffer from the condition than their peers across Alameda County.
Hill says it's no coincidence that large numbers of people of color live in low-lying areas that will likely face the threat of rising groundwater first. "There was either redlining or restrictive homeowner covenants that prevented people of color from moving to neighborhoods on higher ground," she says.
Regulators assess next moves
Naugle, from the Water Quality Control Board, says contaminated sites are at risk of flooding all along California shorelines. "There are literally hundreds, perhaps thousands of these cases in our region alone, not to mention statewide," he says.
He and his team now face the daunting task of what to do, and where to do it first.Over the next few years, Silvestrum Climate Associates will map groundwater depths and test for contamination in four Bay Area counties. Naugle and his water board colleagues plan to use that data to identify the most urgent locations.
California's Department of Toxic Substances Control plans to tackle the problem as well. Grant Cope, deputy director for site mitigation and restoration, would like to work with the U.S. Geological Survey to overlay maps that show groundwater rise onto maps of contaminated sites. That could serve as "an early-warning system" for site managers.
In the meantime, Hill of UC Berkeley suggests residents request a monitoring well to track groundwater levels at nearby locations of concern,especially if they live downhill from former industrial sites like dry cleaners, gas stations or factories. Californians can also review sites known to contain contaminants through GeoTracker, an online database where various regulators track cleanup efforts.
Cope says people can also lobby local governments to "pass enforceable standards that apply to groundwater rise due to sea level rise." He says that means groundwater rise must be taken into account when new buildings are planned, or when toxic sites are cleaned up.
Urban planner Marquita Price wants to make people in her East Oakland community aware of this looming threat. A low-lying affordable housing development, Coliseum Gardens, sits on the location of a former recycling center, ringed by old industrial sites. She says residents notice flooding, but not many realize "exactly what it is, and how contaminated it is, and how damaging it really could be."
Price also wants her community to have a role in addressing the problem.
"I don't want just some outside consultants and companies to come in and carry out the plan," she says. "Our unemployment is crazy out here. So this could definitely be a low-entry job that can provide to the community."
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