Sewage Pumping over hill

Hi

I am modeling a sewer project and there is only one path for the Sewage Force-main. there is a high point in the middle of the path for direct pumping from Wet Well W-7 to Manhole Su-MH-1354 and there was a negative pressure at the high point , so I suggested to put pressure breaker tank Wet Well "W-20" , to overcome the negative pressures My Questions as follows:-

1- is there any other solution than using W-20 wet well ??

2- How to control the outlet flow from Wet well W-20 (2,915.5 m3/d) to be the same as pumped flow to the wet well W-20 (891.7 m3/d), I know that the outlet flow from wet well is based on static head and downstream forcemain size , but is there any way to control, because actually the flow which will enter to W-20 is 891.7 m3/d not 2,915.5 m3/d

Hydraulic model attached in below link

https://we.tl/t-uISz3GDFVr

Regards

Sayed Ali

Parents
  • Usually it is best to put an air release / Vacuum breaker valve at the high point. You don't want a tank full of sewage sitting at the high point.

    Depending on the downhill slope after the peak you may end up with gravity (partly full) flow on the downhill side. How this shows up in the model depends on which solver you use.

    If yo don't put a wet well at the high point, the second problem goes away.

  • Pressure breaker tank will not be filled with sewage and left for along time its volume will be just for 10 minutes storage ( For negative pressure break purpose only), so sewage water in shall be out instant, Moreover I  already tried using vacuum valve, but it does not succussed because the negative pressure value is too high about - 7 bar as shown on the attached screen shot , also using gravity pipes after high point will results in manhole depths with 10 m approximately

Reply
  • Pressure breaker tank will not be filled with sewage and left for along time its volume will be just for 10 minutes storage ( For negative pressure break purpose only), so sewage water in shall be out instant, Moreover I  already tried using vacuum valve, but it does not succussed because the negative pressure value is too high about - 7 bar as shown on the attached screen shot , also using gravity pipes after high point will results in manhole depths with 10 m approximately

Children