Drainage Ditch Design (Upgrade of Existing)

[Engimental]

I am working on the design to enlarge an existing trapezoidal drainage ditch (to obtain greater capacity). The current alignment of the ditch is not straight and does not have even curves. Also, the longitudinal, transverse, and side slopes vary along its length. I am restricted to expanding one side of the ditch only.

What is the best way to set the alignment for this design? I am thinking along the bottom of slope for the side we cannot expand on, and then cut/fill back across the ditch and/or down to obtain a flat transverse slope and increase capacity.

Does anyone have thoughts?

Thanks.

 

[fel3]

Using the bottom of slope of the side you can't change for establishing the alignment makes sense to me.

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"Is it the only lesson of history that mankind is unteachable?"
--Winston S. Churchill

 

[gbam]

In addition to fel3's advice, consider the future construction staking like obstructions and such.

 

[Engimental]

Thank you for the affirmation and guidance. gbam, are you suggesting that following the existing (irregular) alignment could make construction challenging?

 

[gbam]

Just when you are laying out the control consider the field layout... I often hear the expletives from contractors in the field. If you have a logical control the surveyor can easily establish the field control.

 

[Engimental]

Thanks.

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