Our builder has put 3 colverts and extended them with other colverts to carry the water to the creek off our property. My question is can you drive a concrete mixer truck over these that have been buried in dirt and rock. They are the plastic colverts and seem to be working well. I have only seen the metal ones, but have been seeing a lot of plastic colverts since ours have been installed. They seem to be using plastic more than the metal ones now all over around the county.