Create Cut/Fill Volumes to a Certain Elevation

I just got a request from my drainage engineer concerning some earthwork calculations on our pond. He wants to calculate the fill from the existing ground to a specific elevation as well as the cut between the existing ground and the SHWT.

As far as I can tell, the Create Cut/Fill Volumes only calculates absolute cut/fill volumes for whatever models are attached to the file. I have my pond model file and the existing ground attached.

My only thought is trying to clip mask the pond model file above and below these elevations for two separate earthwork runs. I am not sure if ORD will calculate the volumes as if those areas are no longer there if they are clipped. I am not feeling very confident about that particular method.

Has anyone ever tried to do this?