Older cities used the same pipe system for both storm water and sewage setup, usually setup with an overflow dumping into a nearby body of water. When the overflow itself gets flooded it backs up the whole system and causes this
Yeah, this happens in SF too, which uses an antiquated gravity based single pipe system. It works cause of the hills, but it does have this problem. I read that a bit of old Sacramento uses this system too, otherwise you won't find it in California.
This is a good article. The upshot - San Francisco broadened pipes in wealthier uphill areas to reduce local flooding, creating a large bottleneck in a few lower income low-lying areas, so on very heavy rain days, yep, raw sewage backs up into residential areas (lower income, and among the few places in SF that still have a high percentage of children). To make it worse, San Francisco passed laws against paving over front yards, but in typical SF fashion doesn't really enforce the law, so every year, more and more storm water is diverted into the combined sewage/storm draining system. I'm not kidding when I say someone will probably die from this - during one of these floods, someone's dog was electrocuted, and like I said, there are a lot of children living in unpermitted downstairs units with dodgy wiring.
This issue, while maybe not the single most pressing issue facing SF, is the one that goes farthest to convinces me that San Francisco's city government is inept. These are the people who are going to manage the infrastructure preparation for the more frequent and intense storms that accompany global warming?
The city is midway through a 20-year, multi-billion dollar sewer upgrade project, systematically refurbishing and replacing the system block-by-block, road-by-road, neighborhood-by-neighborhood. This is a big reason for all the insane construction citywide.[1]
I don't know the details, but it looks like the flooding described in that article was addressed by the (now completed?) Lower Alemany Area Stormwater Improvement Project and/or Upper Alemany Drainage
Improvements Project, both of which were part of the citywide master plan.
[1] They're also repaving roads after replacement, but it seems coordination isn't as good as it could be, especially in highly trafficked areas. I assume this is why some really bad streets haven't been repaved--waiting for sewer replacement--and why there's a lot of bad patching--repaved too quickly.
Thanks for the info. It's been a few years since the last very serious sewer system backup in the lower Alemany area. I'll do my own research, but if you have any links to this project that address flooding, please post them.
