Wet Well Influent Piping

[kaet]

I am designing a wet well to meet current and future design flows (507 gpm, 910 gpm (2050). To prevent the influent piping from coming in at a very high elevation in the wet well to be above future design lead pump on elevation, I am considering using a drop manhole type inlet into the wet well. When flows increase, the influent will be high enough to be above the lead pump on elev. for 910 gpm. At future flows, the drop section could be plugged or left open. Has anyone ever performed or seen this before? If so, was it effective? Are there any other ideas? I want to avoid having the influent pipe splash into the wet well for current design flows. I also want to avoid using the approach pipe for storage because I don't think it can be very long.

 

[CivEnvEng98]

I suggest an inside drop 2' above the initial lead on setting. If the future lead setting would cause the inside drop to be submerged or less than 6" then I would really consider going with a larger diameter wet well. OR consider a pump change-out for future flows where you could keep the initial float/probe settings the same for future (or close to it anyway). Some pump manufacturers have a model or two where, if the motor is sized properly in the beginning, impeller changes in the future would be sufficient without needing to do a "wet end" change out.

 

[CivEnvEng98]

For clarity, I meant the inside drop to terminate inside the wet well 2' above the initial lead setting. I did not mean to infer that it penetrates into the wet well at that depth. It should penetrate the wet well at typical installation depth.

 

[redbridge]

How deep is the wet well? It is industry standard in my region to allow the influent to splash into the wet well. However I think your idea of a drop manhole type inlet would work well. I don't see why you would ever need to plug the drop manhole.

 

[kaet]

The wet well is going to be 15-20 ft deep (depends on survey which we are still waiting on). I have read that you don't want the influent to splash because it releases odors and causes entrained air into the pump suction.

Thanks,
kaet

 

[kaet]

Just so you know, we've decided to use an inside drop into the wet well instead of an exterior drop. Thanks for the help!

kaet

 

[antony09]

thank you