It’s surprising how much of the first problem still exists almost a hundred years later. There are >750 combined sanitary/storm sewer systems in the country, concentrated mostly in the northeast quarter (north and east of the center of Kansas) plus a cluster in Oregon and Washington, that periodically dump raw sewage into nearby surface water. The models suggest climate change will increase the frequency by increasing the number of extreme precipitation events. The price tag to fix the problem will run to something over a trillion dollars.Report
We’ve got that problem here – in the old parts of town, the storm water drains and sewage outlets from buildings go into one sewer system. Most of the time, it all goes to the sewage plant, but when it rains too heavily for the connections to the sewage plant to route all the water (which it does several times a year) the overflow goes directly into the river.
Greywater systems are not allowed, so that avenue of limiting demands on the sewage system isn’t available. If it were, I might not be feeling so wasteful watering the yard with drinking water all the time.Report
Milwaukee is sort of the poster child for fixing things. Over 25 years they dug almost 30 miles of deep tunnel (300 feet or so down), 17-30 feet in diameter, lined with concrete. Excess sewer flow gets dumped there, to be pumped out and treated later. Overflow incidents were cut from about 50 per year to two. The price tag was almost $3B, much of it paid for by federal grants. The grant program has been replaced with loans. Detroit has a similarly-scaled problem, and not a prayer of being able to pay for a fix.
Separated systems aren’t problem-free, of course. Front Range Colorado had a huge rain event in 2013 and water ingress into the sanitary sewers came worryingly close to exceeding the treatment plant’s limit in my suburban city (pop >115,000). The city recently finished a five-year project that put cured-in-place liners in all the sewer mains that weren’t PVC. The liners have, for practical purposes, eliminated storm water ingress.Report
It’s surprising how much of the first problem still exists almost a hundred years later. There are >750 combined sanitary/storm sewer systems in the country, concentrated mostly in the northeast quarter (north and east of the center of Kansas) plus a cluster in Oregon and Washington, that periodically dump raw sewage into nearby surface water. The models suggest climate change will increase the frequency by increasing the number of extreme precipitation events. The price tag to fix the problem will run to something over a trillion dollars.Report
We’ve got that problem here – in the old parts of town, the storm water drains and sewage outlets from buildings go into one sewer system. Most of the time, it all goes to the sewage plant, but when it rains too heavily for the connections to the sewage plant to route all the water (which it does several times a year) the overflow goes directly into the river.
Greywater systems are not allowed, so that avenue of limiting demands on the sewage system isn’t available. If it were, I might not be feeling so wasteful watering the yard with drinking water all the time.Report
Milwaukee is sort of the poster child for fixing things. Over 25 years they dug almost 30 miles of deep tunnel (300 feet or so down), 17-30 feet in diameter, lined with concrete. Excess sewer flow gets dumped there, to be pumped out and treated later. Overflow incidents were cut from about 50 per year to two. The price tag was almost $3B, much of it paid for by federal grants. The grant program has been replaced with loans. Detroit has a similarly-scaled problem, and not a prayer of being able to pay for a fix.
Separated systems aren’t problem-free, of course. Front Range Colorado had a huge rain event in 2013 and water ingress into the sanitary sewers came worryingly close to exceeding the treatment plant’s limit in my suburban city (pop >115,000). The city recently finished a five-year project that put cured-in-place liners in all the sewer mains that weren’t PVC. The liners have, for practical purposes, eliminated storm water ingress.Report