Upsizing Sanitary Piping

[martin888888]

We have approximately 1000' of 15" Sanitary line (upstream of a larger system) that we are discharging additional flows into. There is one small (100') section of pipe that is laid at .25 slope that is not adequate to handle the additional flow. Is it customary to upsize (pipe burst or open trench) just this one section of pipe in the middle of a 15" system? Or do would you want to upsize this run of pipe and all 15" downstream? You would not design anything like this but as a retrofit is this customary?

 

[bimr]

Don't think there is any requirement that all of the sewer piping should be the same diameter. The pipe should be sized for the hydraulics. A similar situation sometimes occurs when you are trying to extend sewers out over level ground. You have oversize sewers with minimal slope.

 

[martin888888]

Thanks for the response. In this situation we would have a run of flat 18" piping that discharges to a 15" system. I guess that would be ok, since liek you said the hydraulics work. You would not design anyhting like this for new piping nor would any publics work department allow you to.