Levee top width calculator

jloup123

In need of a quick calculator/spreadsheet for required levee top width to satisfy subdivision reviewer.
a simplified, dumbed down version would be perfect. this is not for the Mississippi River but for a very small berm that will seperate a rear lot ditch from an adjacent property.
The berm is 1 ft tall with 3:1 side slopes. I need to provide a calc to justify req'd top width today.

Ran a couple of non-productive google searches..
Thanks for any assistance, links or attachments that you can provide.