The holes are excavations for concrete footings. You can see the plastic caps on the end of all the rebar. The white pipe is pvc plumbing pipe. I would suspect that this area will be either concession stand or rest room. Keep in mind that since the camera is so close we are seeing only that area from home plate to first base. We are not seeing any activity that is happening along the third base line. I suspect that the structure will be steel or precast concrete. If precast concrete it will be like the new parking garages on campus. If that is the case then the structure will go up fairly quick once the foundation work is complete. The speed of erection will depend on how fast they can deliver the sections.