In a hilly town, how does the sewer discharge in the underground pipes "go up hill" in places?

Question

It would not be possible for ALL sewer pipes underground to slant downward. Are pumps used? Unless you know the answer, don't answer, because your guess would be no better than mine. Please answer only if you are sure that you know. If pumps are used, I have never heard of them "breaking down" and causing a back up. And they would almost certainly "break down" every once in awhile.

Answer 1

They have pumps to pump the sewage up hill or along long vertical runs. They normally have back up and/or parallal pumps to get the job done. Sometimes they have three pumps in parallel so if one breaks down, the other two are working. Seldom do all three break at once. But there is also some storage capacity at lift stations where the pumps are installed.

Answer 2

Easy answer. I worked designing and inspecting systems for years.

Gravity fed systems collect waste from most homes in areas and flow downhill to a low point. In modern communities (we are disrearding systems called leach fields) a Lift Station is constructed with is generally a HUGE underground tank and several large pumps that alternately cycle on and off.

Just like a sump pump in some basements, when the tank fills up to a certain level one of the pumps will engage (we are talking Large pumps here). These pumps draw down the fluids and the solids a bit like a blender (yeah... don't think about that part too much on a full stomach) and discharge the slurry into pressure pipe systems that either raise the fluid up to the top of another gravity system (where it continues to flow downhill, eventually reaching the treatment plan) or simply straight to the plant.

Backups? Doesn't happen too often. If the pumps fail an alarm goes off in the treatment plan and someone is quickly dispatched with a temporary pump if needed. However the second pump is still there. Even if that doesn't work, there is plenty of 'extra' room in the large tank to last a day or so.

What is really bad is when the discharge pipe gets broken or hit by a contractor working somewhere else. Often it would be broken when the pump was off so people thought it was an abandoned line. Then, about 5 or 6 hours later the pumps would kick on and begin to fill his trench with a rather unique backfill.

..but that's another story.

Hope that helps.....

Answer 3

I can only speak for the code in my area. All sewer drains are required to have fall to the treatment and or pumping stations. The pumping stations have multiple pumps and also have holding capacity, this capacity for this area is enough for 12 hours of median flow. When a pump goes down there is an alarm and the employees manning the station take action. Or at least they are supposed to.

Answer 4

The sewage treatment plant is placed at the lowest level possible. Pipes run downhill for as long as possible, then there is a pump station to assist over the hill. Pump stations are located where necessary. They are in small buildings and are labeled. Maintenance is done on them regularly.

Answer 5

They are called lift stations. The sewage is collected in them and pumped to the treatment plant, or to larger lift stations. This is typical in not only hilly areas, but basically all over the country. It is unusual for sewage to enter a treatment plant simply by gravity.

Oh, by the way the pumps do break down. Most lift stations have multiple pumps installed so they will not overflow.

Answer 6

They try to run sewer pipes downhill as much as possible. In those places where they do have to go uphill, they make use of vertical section of pipe before that section (to give some pressure head that helps force material up the next section) and they don't let the pipe run above the highest point of that vertical section.