A company should go in with the plan of being as clean as possible and should have a plan in place for restoring the environment when it leaves. I'm not an environmentalist, but I think stewardship has to have a place in planning. If that means that a company's efforts surpass local laws, then so much the better.
I've seen evidence of what Chevron did, and they deserved to have to pay for their negligence in that case. There is no way that leaving stand pools of industrial chemicals is following good stewardship.