beej67: You are absolutely correct. It is the estimators job to build his own 3d model and check for accuracy. Most of the time if I get a file with the "z" value applied or a TIN layer I do not use it. I will clear all "z" values and start with "annotation" lines. Then build the model...
Civil Engineers; What is your reason for not giving up the CAD file for estimating / earthwork calculation purposes?
The oldest excuse is that someone could take the data and perform some type of malicious act with it. For this, you execute a CAD release agreement and do not include your stamp...