I don't know any code section that requires solid footing in front of equipment. I thought about making a proposal on that for the 2005 NEC, but didn't get around to it. It should be common sense I think.
If there was such a rule it could also affect Panelboards and equipment installed in stairways.
Ryan I don't se working clearance as an issue here. As Bill said there is nothing about working surface. I don't think you could fail this. The poco may have the authority to disallow this (maybe won't energize?) if it does not conform to their specs.
Is there nothing in the Building Code about guarding from falls, etc? If I put in a small fish pond on my front lawn that is 12" deep I'd have to put a fence around either it or the whole yard with a self-latching gate.
Maybe the POCO would have something to say if you point out the possible danger to their employees.