Glad you learned the lesson, but so sorry you had to learn the hard way! ;-) Be sure to incorporate lots of organic matter of some kind to the top soil that you obtain. It should be tilled in well with the mineral component so that you don't create artificial layering. (Again, it should be added to the entire planting bed, not hole-by-hole.)

You may want to have some pH tests done once you bring in the top soil. Also, cement can leach lime into a surrounding soil system, and may raise the pH over time.

We had to do the same thing in our front yard, as you are doing. Drain pipe was essential to our project, so we rented a trencher for the morning. What a back-saver!

Good luck, alexh!

Plant in the dirt you have or plant in new dirt dumped on top. The problem with mixing amendments into the dirt you have is that these will decompose and disappear long before the camellias have gotten old and died. So, they will end up having to grow in the dirt you started with.

Peat dug into a clay soil in Oklahoma had vanished a year later.