Column footings

More excitement this week outside the Library. Yesterday, there was a big cement truck outside as workers poured cement to make the column footings for the foundation of the addition on the north side of the building:

Here's a quiz and a little lesson for you. Any idea what these are?

If you guessed helical piers, you're right! These are basically giant screws that go deep into the ground to support the foundation of a building. They can go down REALLY deep (with extensions added) in order to reach just the right density of soil needed to support the weight of the building. They're installed using a special machine that has a gauge on it that tells workers whether or not they're at right depth. Our foreman told us that they are already putting these piers in at the front of the building (where the lobby used to be) for that addition. Guess how deep they had to dig?? 37 FEET! Wow.