Still Under The Radar For Most, Coastal Groundwater Rise Coming For Coastal Infrastructure

[hatrack]

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In talking with experts about groundwater rise, what often comes up is that it’s more complicated and harder to adapt to than sea-level rise. Any solution to one aspect of the problem can create a cascade of others. Take, for example, something as straightforward as sanitation. Ordinarily, in most parts of the United States, when you flush the toilet one of three things happens, depending on where you live: it goes out to a cesspool, a septic system, or a sewer line. But groundwater rise presents increasing challenges for all three.

Cesspools are essentially concrete cylinders with an open bottom and perforated sides. Especially in coastal areas, the cesspools, which should be dry, instead find themselves constantly inundated, says Josh Stanbro, a senior policy director for Honolulu’s city council, who until last January was the city’s chief resilience officer. “They’re now sort of always wet,” he says. Microbes stay alive because they are wet, and because there’s so much more water around, they can leach out.

And Honolulu is not the only city with this issue. Miami-Dade County is facing similar problems with septic tanks, which in theory provide a layer of filtration that cesspools do not. But to do that filtration, the systems require a layer of soil two feet deep, and that layer shrinks as water tables rise. Already, 56% of the county’s systems are periodically compromised during storms. By 2040, estimates suggest, that number will rise to 64%. Failed septic systems can contaminate the local aquifers that a community depends on for drinking water. One workaround is to switch those households and businesses currently on septic or cesspool systems over to sewer lines. In Miami-Dade County, the estimated cost for that shift is $2.3 billion.

Nor are sewer systems a panacea, cautions Berkeley’s Kristina Hill. “Most American sewer pipes, both sanitary and storm sewer pipes, are typically cracked, because we do such bad maintenance. We’re like an international joke,” she says. “People start conferences in civil engineering in Europe with slides of how bad American systems are, to loosen up the audience.” Those cracked sewer pipes let groundwater in. And in places like New York City and Boston, which have what are known as combined sewer systems, water from rain and water from raw sewage mingle, so there’s less space in the pipes. This is why as groundwater rises, places like New York City’s Jamaica Bay community end up with liquid bubbling up from storm drains during high tide.

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https://climatecrocks.com/2021/12/14/sea-levels-hidden-cost-rising-ground-water/#more-69962

[hunter]

1. Plenty of European cities have wretched sewers and sewage treatment plants.

Their regulations may look good on paper but their sewer systems are leaky and frequently overflow. Upsets at the treatment plants are frequent as well.