Grounding a magnetic levitation circuit

I need help understanding the circuit attached, from what i understand is that i can power it from a 12V mains adapter. The one i have is 1 amp which i think is enough. But more importantly for the grounds, that i should connect them all up to the ground coming from the 6 pin on the left opamp. As though this ground would act as a central one, with all the other ones connected to it. Is this correct or not, if not then please explain to me how i should ground this circuit.
I claim no rights to the content in the link and am using it for my own recreational purposes.

http://uzzors2k.4hv.org/projectfiles/magneticlevitator/Magnetic%20Levitator%20circuit.GIF

Those are common grounds. If they where not common grounds then they would be noted differently.