Pressure sewer

[tommasobrizzi1]

Good afternoon from Florence.....
I am a waste water designer. Excuse me for my english.
I have to design a 900 meter pressure sewer.
I have to pass 2 bridge and so i chose pressure sewer.
But the end of the tracing is 3 meter under the start point. i 'm frightened that the pipe become empty when the pump turned of. The flow is 10-40 litre/second
can i design 2 different pump station with a feature in gravity sewer?

Thanks a lot

 

[mflam]

Your concern is valid. You should not layout the pipe in a way that the force main will drain. I would design to pump to a high point, let the force main open into a manhole and then go be gravity to your end point. The force main can rise and fall with the terrain (for your bridge crossings, etc.) but the end of the force main should be on an up gradient so it will stay flooded when the pumps aren't running.

 

[BRIS]

I agree with mflam avoid pumping downhill if possible. Pump to a high point with a continuous gravity slope thereafter.

If that is not possible then one of your main concerns may be release of air and odour control each time the sewer is reprimed on the start of pumping.

Can you explain what you mean by "can i design 2 different pump station with a feature in gravity sewer?"