Watching Ask TOH yesterday, and there was a segment where a woman in Chicago had 4′ of sewage back up in her basement. Seems a check valve had failed during a heavy rain event.
Question is, what kind of bozo’s designed a single system to handle wastewater (WW) and stormwater (SW)? It showed standard inlets on streets that drain into the combined system.
Do the inlets stink during the summer? How does the WW treatment plants handle heavy rain and melt events without overloading and dumping raw sewage into the effluent outfall?
Is this SOP all over the north?
Replies
There used to be a lot of sump pumps and basement drains connected into the sanitary sewer system here. There are separate storm sewers, but all fluids leaving the house interior went into the sanitary line.
That practice was stopped a long time ago and anytime a plumbing permit is pulled on an existing structure, the basement drains and sump pumps have to be disconnected from the sanitary lines. But, there are many that are still grandfathered.
http://www.quittintime.com/ View Image
Well. I was just floored when I saw the hook-up, and the street inlets. Never saw anything like it, and I've put in miles and miles of sanitary and storm sewer, and surveyed for 3-4 treatment plants, and dozens of lift stations.
No wonder the rivers in the north were so dirty.
Wes be kleen down hyar...
Don't ferget that we northerners send our trash south. If'n it's not in your water, you better watch out...
http://www.detroitnews.com/apps/pbcs.dll/article?AID=/20090214/METRO/902140373/1409/METRO
It will be!
Yeah, we've got a bunch of them in Florida.
He F'sUp down here, and he gets the attention of the TDC, I feel sorry for his Yankee adze.
It's still the 1950's out Huntsville way...
We'll leave you in charge then.
Thank you.
Flush twice because it's a long way back to Detroit...
It actually was quite common, but has been changing. Slowly, but it is changing. Our county and local city are in the process of coming up with $500million to change our system.
It's not done today, but old cities, whose sanitary systems are 150 years old or so, usually had combined systems. The feeling was that rain would wash the waste through the system and flush it clean periodically. That was before waste was treated.
It was a standard engineering practice back at the turn of the last century. The goal was to get it out of town, and into the river. So, it is still the system used in most major cities, that are a century old. Phoenix, and Las Vegas, are the only two that come to mind with no combined systems. And, that is because they were tiny little places a century ago.
They didn't treat it back then, just dumped it raw into the river. Now many cities are still using the combined sewer system, and treat the base flow of the system as sewerage before releasing it into the river. But, high flows generated by rain events, discharge to the river, with only the base flow portion being treated.
The cost of upgrading to dual systems, is included in the trillion dollars the ASCE says the nation needs to spend to get the infrastructure up to current standards.
It is really hard to get people to vote for levies to upgrade systems such as these, because so long as their commode flushes, everything is fine. And, the cost is high, because nearly all of it runs under roads, where every other utility is also run. You have a lot of conflicts to resolve during construction, (read change orders), and then when you get done, the road needs paved.
Don't know of any cities down here that have combined systems. Even San Antonio, and it's been around since the 1600's.
Do the storm sewer inlets ever stink in the summer?
Wilmington De still ties some storm systems into the sanitary. I dont know the requirements for when you connect to the combined system vs. when you infiltrate, but I know my sis bought a th in the city and the downspout leders come into the house and tie into the combined system inside.
Freaked me out when I was finishing the basement and a rain shower has water running into the 4" sewer drain. Noisy as he** and wierd.
Inspectors said it was perfectly normal.
Yes, all the old north cities did it but I was amazed to actually see it in new construction.
Treatment plant either is huge or just bypasses into the Delaware River during storm events (which is way uncool!!)
>>Wilmington De still ties some storm systems into the sanitary. I dont know the requirements for when you connect to the combined system vs. when you infiltrate, but I know my sis bought a th in the city and the downspout leders come into the house and tie into the combined system inside.<<
Wilmington, DE, required all new construction to feed rainwater run off from roof gutters and downspouts to be fed to the sanitary (combined) sewer until about 2001 or 2002. Just outside of the city limits, rainwater is prohibited from being fed to the sanitary sewer, and has been for as long as I can remember.
Many / most existing storm drains are connected to the sanitary sewer in the city. As of 2001 or 2, new construction storm drainage must go onto grade.
We got caught at a H4H project right at the transition - city approved plans said "must tie into sanitary sewer"; by the time the framing, mechanical & electrical inspection rolled around it was prohibited.
A few sections of the city have separate piping systems in place - "few" is the operative word.
Connection SOP was to just put in a trap at the tie-in point(s) for the rain water - no smell.
>>Yes, all the old north cities did it but I was amazed to actually see it in new construction.<< "New" must be pre-2002 or it's illegal here.
>>Treatment plant either is huge or just bypasses into the Delaware River during storm events (which is way uncool!!)<<
That is exactly what it does! Treatment plant is big - can viewed very well from the Cherry Island Landfill, construction debris section or from the exit road down the hill on the way back to the scales. You can even get a good look at the flood gates which enable one of the holding ponds to dump directly to the DE River.
In fairness, they do the best they can, during major rain events they isolate the "dirtiest" of the ponds and then open the "cleanest" pond and release rain plus "newly arrived" sewage to the river at the minimum rate which is needed to prevent the pond from overflowing.
Jim
Never underestimate the value of a sharp pencil or good light.
Hmmm Jim:
You know city code, but this thing is post 2002
It was a tear down and rebuild so maybe since the existing structure was tied in, they approved it.
I dont know the details and I know that the city approved everything and it was inspected.
As you know, city is pretty thorough with inspections.
I just finished the basement so did not touch the SWM.
(toughest firestop inspection I ever had in my life. Inspector took picts because he was impressed with how good it looked. I still failed the 1st inspection and had to add a few fireblocks, but they checked everything I did!
As the others have said, this is a legacy of earlier concepts in sewerage management. Here in the Chicago area (as you noted) many of the sewers are combined storm and sanitary. But "Sludges'R'Us", also known as the Metropolitan Chicago Sanitary District has also built HUGE tunnels under the city that connect to large reservoirs, called the Tunnel And Reservoir Project (The original TARP).
These tunnels are considered a primary storage facility for storm water runoff, and if necessary more storm water is pumped into the reservoirs. And then what happens to the water? IT GOES INTO THE WATER TREATMENT PLANTS!!
Why treating it? All sorts of nastys get into the storm water. Why, I even heard of people dumping waste oil from their cars into the sewers, if you can believe that! <g> So, we are going back to the original idea, except it doesn't swamp the plant. The big storm surge is stored, and pumped into the treatment plant at such a rate that it operates smoothly and slightly under maximum capacity. This way the facility operates at its most efficient manner.
Interesting solution to the material in stormwater runoff. Down here we usually use "retention" and "diverter" catchment basins that filter the runoff through coarse, medium, fine gravel, then sand, then it goes to the local river/lake. Doesn't remove oil, gasoline, PCB's, or other chemically soluble material, but particulates and trash like styrofoam and other plastics.
The event mentioned in Ask TOH was 10", which I guess completely overloaded the existing system. We can have that much rain 2-3 days in a row from a hurricane.
Thanks for the info. I was totally ignorant of combined systems.