Inline horizontal backwater valve

[figz]

Hi all! New guy here! Hope someone can help.
Please see photo. I have a 4" horizontal drain pipe that leads to the storm drain. It's sends water from our french drains, dehumidifier, and condensate pump out to the storm drain. However, in big floods (hurricanes, etc), water can come back up into my house. (Not good!) I'm looking for a solution, but most plumbers tell me the only answer is to dig up the yard (5' down) and put in a traditional backwater valve. I think there has to be something we can do inside my house to allow water to go one way and not the other. Anyone have any ideas?
Many thanks!
-figz

 

[plbgbiz]

To put a backwater valve in, you will need to connect it to the pipe somehow.

Chip out the concrete from around the existing pipe, attach a rubber coupling (Fernco or Mission brand), extend a piece of pipe from the coupling into the basement, and then attache a backwater valve.

Yes, you could do it in the space pictured but it would have to extend into the room rather than be flush against the wall. Also, depending on the volume of water entering (you mentioned big floods and hurricanes), the rubber coupling might not hold back the head pressure of flood water surging against it.

Even though it is not as easy, installing it in the yard may be best.