Hi Friends! This drain is right in front of the entrance to our basement-level garage, at the bottom of a ramp leading down to it. Heavy rain makes it overflow, even with the grate off (I know it needs to be cleaned).

There’s about six inches of loose silt in the bottom, but I think maybe that pipe is a siphon that drains off the water? I put a probe in there and it’s clear, and I can’t feel anything else digging with a shovel.

Any suggestions for improving the flow?