WATER DISTRIBUTION LINE CALCULATIONS

[riwhite]

I'm up against one of the top firms in our area that has moved in on my project with their big dog and pony show with a new route for a high service water line and booster pumping system.
Their route they are claiming the can run half the line I have proposed and boost the pressure to get the line up the ridge to my client.
The pump station will be at Elevation 556 MSL and must reach Elev 986 while maintaining a 55 psi minimum when it reaches our connection for our system pressure.
There is 22,935 LF of 6" PVC Class 200. They have concluded they can get 120 gpm through this existing pvc line.
Maybe they have a new method that I didn't learn but I can't see that this would work at all without exceeding the allowable pressure on the pvc.

If someone would make me a double check maybe my client might not believe the big guys are always right.

 

[katmar]

What is it that you want double checked? The static head of 430 ft (185 psi) plus the end pressure of 55 psi already exceeds the allowable pressure, so it seems to me that the flowrate and friction pressure drop are irrelevant. At 120 gpm in a 6" pipe of 22,935 ft I get a friction drop of only 11.5 psi.

You used the expression "run half the line I have proposed" and I am not sure what you mean by that. Certainly using a 12" pipe will not help in maintaining the pressure below the rated pressure.

Katmar Software
Engineering & Risk Analysis Software

http://katmarsoftware.com

 

[rconner]

The terminology that the "big dogs" have a "new route" that can get the water delivered through the "existing pvc" is a little confusing as to what is actually going on here. Are you saying this piping has already been purchased for these pressure/flow conditions, stacks sitting there but have not yet been installed, or what? In any case, unless there is something you don't know (e.g. is the Ownere happy e.g. with all aspects in the present day associated with intermediate break tanks or booster stations etc.?) this would appear to be somee risky business for someone.

 

[cvg]

recommend you do a simple epanet model and verify for yourself what works and what doesn't

 

[BigInch]

Katmar,

I assume he means somebody drew a straighter line then he did, but it went up a hill and they need a booster pump to do it.

Besides overpressure, it sounds more expensive if you include the land, security, telemetry, maintenance costs, power connections and the power to run the booster pump for the next 25 years.

http://virtualpipeline.spaces.msn.com

"What gets us into trouble is not what we don't know, its what we know for sure" - Mark Twain