core drilling stamped concrete patio

This is a small residential project we underwent in York, SC where we core drilled 4 six inch core drill holes through stamped concrete. The hole nearest in the center of the stamped concrete patio was 14 inches deep which meant that we had to drill down through the foundation underneath the stamped concrete to reach the dirt below which is what the homeowner wanted. Then they were to set 4 wood 4 x 4 columns in the holes upon which the cast fiberglass column over it for support.