2" stack vent for 6 bathroom groups 2 washer machines

My boss asked me to do this in a small appartment building.... This just seems wrong.

Am i safe with two 2" stack vents... 3 groups per vent

It depends on how your code is written and what its parameters are. If you code requires that the vents out the roof have the save AREA as the incoming sewer, then you would need four 2" vents, but you also have to know what your code's limits are as far as fixtures connected to a 2" vent. I think one of these two requirements will negate just two vents.