Force Main to Force Main Connections

[Dredger01]

Has anyone come across a case where a new force main is tied into an existing force main? I've got a development situation where a residential lift station feeds a 6" force main, which then passes across the frontage of a subject property. It would be convenient to tie into the existing force main if possible, rather than gravity draining to the lift station.

 

[jgailla]

This is quite common. You can do a wet tap just like a water main.
The problem is getting a pump that functions in all pressure ranges of the tie in point.
The utility will have to approve the tap and give you the tie in pressure from their model.
If there is a nearby lift station, the utility may make you run the extra length to the station rather than tying in upstream.

 

[bimr]

As jgailla stated, this is not uncommon.

The issues are:

1. The force main must have the capacity.
2. The pumps have to be capable of pumping at the condition when all pumps are pumping at the same time and there is a greater pumping head.