Grand and Bates relief tunnel (large storm sewer)

[Chris]

Some time ago, the Grand and Bates relief tunnel - being burroughed underneath south St. Louis city by a TBM at the time, was mentioned on this board.

I just now realized it, but the huge storm sewer outfall me and a friend discovered downhill from a riverside park was in fact the outfall of this drain.

You walk in on the bank of the Mississippi into one of two concrete box culverts, each about 5' tall, 7' wide, and maybe 60 feet long. They lead to a room with a steel grate ceiling about 50 feet up. The room is 20 or 25 feet wide and about 8 feet long. In the back of this room is a two huge, very heavy rubber doors. We couldn't lift them. Behind these huge doors should be the Grand & Bates tunnel.

The tunnel should be a RCP about 8-12 feet in diameter and well over a mile long. It should be about 50-100 feet below street level, probably deeper the further up you get. It probably has side tunnels all along it. I guess the next thing would be to try to find a manhole leading to it.

[White Rabbit]

It's still being burrowed out? I thought it was finished.

And could you lift those rubber doors with a car jack or something?

[Chris]

No, it's finished now, but I think it was under construction when it was first mentioned on here, but I could be wrong.

The rubber doors are common on large storm drain outlets in St. Louis. They're made of about 1" thick slabs of rubber with big bars bolted to them. It's almost like the storm drain has to practically fill up to put enough pressure on them to open. They're VERY heavy and I couldn't get them to budge at the time (this was a few months ago). I don't think a car jack would help, but a pry bar might. I think the best bet would be to enter through a manhole upstream. Just need to find one.

[memory_machine]

A friend of mine was telling me that she found a storm drain outlet by the river, but she assumed it was under construction because of the large rubber flaps she found. I didn't realize that these were standard on drains in St. Louis. Is this a common thing nationwide? I've never heard of it.

[Chris]

I have no idea where else they use them, if they do, but I know of several large tunnel openings sealed by them here in St. Louis.