How deep (verticaly) are typical storm drains (gutter drains)?

Question

Just an estimation would be fine

And can these drains become clogged by build up of rubbish?

Answer 1

id go down a foot and put crushed stone around the drain.the drain should have holes drilled in the bottom to allow the water to come up and travel down the pipe to where you want it.I used 50 gallon plastic drums (barrels)drilled holes in the to let them leach out slowly

Answer 2

If you're talking about roof gutters, about 4-5",
and yes, they get clogged all the time.