Flowrate required to prevent sludge buildup in raw sewage pipeline
Flowrate required to prevent sludge buildup in raw sewage pipeline
(OP)
I have an 8" HDPE raw sewage pressure main 13,000' long running uphill a total of 110'at almost a constant slope with a few 5' dips in elevation (under culverts, etc.). What flowrate must be maintained to prevent settlement of sludge from plugging the pipeline over time(scouring)? Currently the pumps only run a few hours per day until future housing developments tie in (years from now) and I'm insisting they run long enough each time to totally flush the line plus 10-15% more.
Do I have a problem or not?
Thanks
Do I have a problem or not?
Thanks





RE: Flowrate required to prevent sludge buildup in raw sewage pipeline
RE: Flowrate required to prevent sludge buildup in raw sewage pipeline
When starting the force main, your pumps should operate at the higher flow to resuspend the solids. You can then throttle back to the lower flow rate.
You may also have a problem with air pockets at the lower velocity. You need at least 3.5-4 ft/sec to force the air pockets through the force main.