How about against corporate requirements, industry specific requirements or any other requirement (not related to legal requirements) that you must meet? Remember, this only concerns those requirements that are related to environmental stuff.
One immediate "other" requirement is ISO 14001:2004. Evidence of this evaluation is your internal audit and the management review, and it may possibly be the only one you have.
We who have seen war, will never stop seeing it. In the silence of the night, we will always hear the screams. Joe Galloway