[nine_k]

Nuclear power plants have secondary and tertiary overflow reservoirs, intended to capture any uncontrolled dangerous outflow if things go wrong.

I wonder if chemical plants have something similar, a way to contain an uncontrolled outflow of toxic stuff if the normal flow of neutralization fails.

BTW this likely means quite a bit of land used up by such a reservoir which is ideally never needed, but must be present.

[Animats]

Yes. In Silicon Valley, if you go to Bedwell Bayfront Park, which is behind Meta/Facebook HQ, there is, on the bay side, a small sewerage treatment plant. There's a fenced concrete-lined pond, usually empty. That is a sewerage overflow containment pond. It's next to a hiking trail, so it's easily visible to the public. That whole park, by the way, is a recycled garbage dump. So is the bay side park behind Google HQ.

Wastewater plants have other ponds and tanks which are part of the process, and they're usually full, with liquid moving in and out, accompanied by stirring, air, and chemical injection. A big empty one is a backup system.

Real engineering.[1]

[1] https://www.epa.gov/sites/default/files/2014-09/documents/la...

[mikestorrent]

Does the area smell, or is that all captured somehow? I've been to the plant in my city many years ago and it only smelled in certain buildings.

[refurb]

I worked at a plant and the answer is yes. The EPA requires it.

It can range from overflow tanks to capture spills to concrete “pools” around the entire operation that capture any catastrophic leaks and direct it to underground holding tanks.

There are a ton of highly toxic industrial processes. Properly designed plants and safety infrastructure means it’s never an issue.

[overfeed]

> BTW this likely means quite a bit of land used up by such a reservoir which is ideally never needed, but must be present

This is enough to earn chemical plants a spot on a future "BANNED in California 2" article, because it's "clearly" overregulation.