Submerged pipe outlet

[flyers7]

I encountered a situation where an earthwork outlet drain was proposed to be connected to the existing watercourse. The pipe will sometimes be submerged, and I am concerned about the backflow into the gutter. Can somebody confirm if that is true, and if so, please explain?

 

[waross]

There are suitable check valves available for that situation.
The worst that I have seen;
The construction crews read their survey instruments backwards and sloped the drainage ditch the wrong way.
There was no check valve.
There was a lot of back flow.
Eventually the situation was remedied, including the installation of a check valve.

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Ohm's law
Not just a good idea;
It's the LAW!