Wow, construction is not my area of expertise. I needed to ask questions of Ryan Schertz, the project superintendent of our site to see what all this equipment is doing.
In the background you see a yellow excavator. This machine is taking the engineered fill off the pile and depositing it into dump trucks. The dump truck then takes it back to the excavated building pad for proper placement and compaction.
The middle tractor, with the green cab, is pulling a disc. This disc is mixing equal parts of the soil, excavated from the building pad, with imported sand. That combination creates the engineered fill that is needed for the base upon which the library will be build. Once it is mixed, it is put back into the hole, then compacted to a specific percentage using a sheepâ€™s foot roller which is the yellow equipment you see in the hole.
The gentleman, next to the sheepâ€™s foot roller, is sampling the compacted soil to be sure it has the right density and moisture content. He will take the sample to a laboratory to make this determination.
And all of this happens before we have the correct base to begin digging for the foundation.