Combining forced sewer pipes
Combining forced sewer pipes
(OP)
Guys,
Is it ok to combine the forced sewage pipes from 2 sump pits before they get into the inspection chamber(manhole), i think they must be taken separately till the inspection chamber.
Is it ok to combine the forced sewage pipes from 2 sump pits before they get into the inspection chamber(manhole), i think they must be taken separately till the inspection chamber.





RE: Combining forced sewer pipes
If the sumps are located far apart, it might be advisable to keep them separate to minimize the piping.
RE: Combining forced sewer pipes
The first sentence in your reply is unclear, can you please rephrase it?
RE: Combining forced sewer pipes
These are commonly located in the same proximity so combining them makes sense.
RE: Combining forced sewer pipes
RE: Combining forced sewer pipes
If you have solids, there may be some concern for plugging when operating at low velocities in the combined forcemain.
RE: Combining forced sewer pipes
Bimr, kindly can you let me know what do you mean by plugging? Is it blocking?
RE: Combining forced sewer pipes
If you size the combined forcemain for 2 pumps, you will see a reduced velocity if only one pump is operating.
The design is more simple if there is only one pump per forcemain.
RE: Combining forced sewer pipes
Backflow is prevented by a check valve installed downstream of each pump, typically in the horizontal portion of the piping in the elevator shaft.
This is likely a specialized situation where the pumps are close in location. If they are not, separate pipes would likely be a better design.
Typically, sewage pumps, if receiving black water, would be designed that the pumps can pass 2" solids and possibly have impellers which will shred/grind/etc. solids to less than 2".
I agree with bimr to size the piping for one pump to keep the velocity up and push the waste downstream, especially if the pumps are not going to operate often. Once solids settle out and dry out, it is very difficult to dislodge them.