American Concrete Pipe Association Pond culvert calculation procedure 3

[Andy J]

Does anyone know of a culvert calculation procedure from the American Concrete Pipe Association on how to correctly calculate flows through a culvert discharging from a pond?

I have a regulator insisting that I use the manning's formula which doesn't take into consideration inlet losses, outlet/inlet controls, low to no velocity of water entering the pipe at the inlet due to ponding??

The culvert will be partially full and I been using a modified orifice equation and heard that it came from the ACPA?

Or if someone can point me in the correct direction to some research papers. Manning is giving me flows 4 times higher than FHWA or the orifice equation which both give me similar values.

 

[r13]

Here is the link of ACPA technical web page. Looks like they use Manning's equation too. Link

 

[Andy J]

THANKS,

I'll take a look.

 

[r13]

I think you'll be interested in this presentations - "Comparison of Pipe Flow Equations and Head Losses in Fittings", Link

Another seminar notes - "Spreadsheet Use for Partially Full Pipe Flow Calculations", Link

 

[cvg]

you have to consider inlet/outlet control and losses. you cant just assume a full pipe. in fact for a fully submerged inlet as in a pond, you almost certainly will have inlet control (orifice) with only partially full pipe for most water depths.

suggest
FHWA –NHI- 01-020, HDS No. 5 Hydraulic Design of Highway Culverts

 

[Andy J]

How do convince a hard headed regulator? All he uses is a manning's formula. So he gets flows way higher than I get and I don't think it is right for me to put a stamp on something that is wrong.

Is there some research out there that says using just the plain mannings formula is wrong?

 

[r13]

See my last link, it uses manning's equation for partially full pipe flow conditions.

 

[Andy J]

I find it very disturbing that someone who doesn't even have a PE can force me to do something wrong. Guess I can always just say no, but I don't want to leave the client hanging either.

 

[Andy J]

I'll calm down and look at the references you have given me. Thanks, I'm just at the end of my rope with this field right now.

 

[r13]

If the manning's method produces the worst situation, I'll advise my client, let him decide if he/she wants to go along with that decision or not. It's not your fault.

 

[bimr]

These calculations can be found in the Federal Highway Administration hydraulic design manuals as noted above by CVG:

FHWA

 

[robyengIT]

ACPA Design Data for culvert (circular & boxes) : hoping of some utility for SRE

https://mega.nz/file/tQFgxaga#Dva1Fx-fAFWAo2E2EGBg4wsTosnIs41CJ4XTwkmz1zo

 

[fel3]

Andy J...

"How do convince a hard headed regulator?" Gently. You may want to hand him a copy of the FHWA publication and let him know that you are following an established and well-vetted procedure that covers more operating scenarios than Manning's can handle.

"All he uses is a manning's formula...Is there some research out there that says using just the plain mannings formula is wrong?" You might explain the applicability limits of Manning's:
[ul]
[li]Manning's can be used for full pipe flow, which requires both inlet and outlet to be submerged.[/li]
[/ul]
[ul]
[li]Manning's can also be used for UNIFORM open channel flow, which requires both inlet and outlet to be unsubmerged at the same depth.[/li]
[/ul]
[ul]
[li]Regardless, there are still entrance and exit losses to contend with and that's not something Manning's does.[/li]
[/ul]
[ul]
[li]Manning's cannot handle NONUNIFORM flow in the culvert, which is very likely the most common condition for your culvert.[/li]
[/ul]

If he won't budge, is there a supervisor you can talk to?

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"Is it the only lesson of history that mankind is unteachable?"
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