30 Days of Biking - Mystery tunnels

Biking along the Mississippi - especially before the leaves come out - you can see mysterious inlets, ravines, and the dark entrances to caves near the waterline. Some of these are real caves and others are man made. In either case it isn't everyday that something new shows up on the cave map.

So, I was quite surprised to see that some new caves were being dug into the bluffs right along my bike route. Equipment started showing up a few weeks ago and they cleared two areas. Here, there was a need to excavate more above grade so they built a gravel driveway up to the site.

I assume the corrugated metal tubes are to stabilize the entrance. The limestone in the cliff is very convenient for free landscaping mater...I mean very loose.

At the second site (below) you can see the shattered rock around the entrance. Once past this initial stage, they started tunneling into the cliff. I will get some better photos since the work is pretty cool to watch. The tunnel itself has a rectangular profile and so far it looks like they are going to leave the walls natural stone.

I have tried to ask one of the construction workers what the project was about but they aren't too responsive over all of the drilling noise. My assumption is that since these two tunnels are just below the East Bank of the University of Minnesota campus that they are meant to service the buildings on top of the cliff. In fact, just upstream there is an underground archive that does just that. This stuff is quite cool! And, all on the bike route to work...