Another Hole

There used to be a vacant lot at the corner of the street where I live. It was covered with nice mature trees and was just across the alley from my apartment building. A year ago the trees were cut down and then a few months later very deep holes were drilled and filled with rebar and concrete. That process was finished last spring. When I left at that time they were uncovering the piers located around the edge of the property, cutting them off at a certain height, and preparing to construct a reinforced beam on their top around the property.

When I came back this fall, the lot was a flat piece of land with little sign of previous construction. On the lot was this very heavy machine pushing piers deep into the earth.

Soon that process was done and a blue construction fence was erected to make sure no one but workers could enter. A big backhoe was brought in and loaded trucks throughout each night, creating a growing hole in the ground. During the day they started to erect very large steel pipes horizontally across the hole being dug.

Notice the piers around the edge with the beam on the top. The pipes are being used to form a truss to hold back the retaining wall while the hole is being dug. With buildings and streets on the edge of the site, great care must be taken to insure that there is no shifting of soil.

In the above picture, the final grade for the floor is being determined and all concrete piers are being cut off just below floor level as you can also see in the next picture. A thick reinforced floor will be poured up tight to the retaining walls. After that has cured to a particular strength, the pipes will be taken down to allow the building frame to be built. Notice the backhoe at work on the floor. When finished they will lift it out.

As I was writing this I went out to get the above picture along with some others. Workers were cutting off the piers at floor level. That I understand. But the piece they cut off they drove a wedge up the side under a rebar. I wanted to stay and watch through a small opening in the fence to learn more, but I felt this tap on my shoulder and turned to see an unhappy construction worker standing next to me gesturing that I leave. I thought it wise to leave, but I will be back. I saw too much this morning. My construction mind wants to know what those workers were going to do with those cutoff pieces and why each one was being prepared as it was.