[color=#000000]Max,
In your case all could not be lost as if your white wire in the dryer circuit is connected to Neutral you will only need to find a local source for a suitable ground. This could be another local circuit, a copper water pipe, or through the wall or floor to another earth ground even if you have to drive a stake outside. This ground only needs to be a #12 wire as it is only for safety.
I am working on the much owed pictures and schematics today but to help this thread along I think we need to know what your planned depression control will be. You may ask why but this seriously affects wiring. The three choices as I see it for controlling depression are 1.) Mechanical 2.) Electronic 3.) Electro Mechanical.
Mechanical is like most of the SF benches and the MSD bench where the switched on motors run WFO and you control air flow with a valve (Infamous Pudding Bowl).
Electronic