In your role as employee of the agency, you are likely to find that some categorical exclusion questions -- like the one about purchasing the cars -- are pretty easy to answer. No, there's virtually no realistic chance that buying some cars will have a significant impact on the quality of the human environment. Others, however, will be harder to address. For example:

• Is the office that will be remodeled in a historic building? If so, do the interior elements of the building, including the office, contribute to the building's significance? If so, will they be altered? Or will the project require, say, replacing windows, and will that have visual effects on surrounding buildings?
  
  
• Does the surplus land contain archaeological sites? Indian spiritual places? Places used by local people for traditional subsistence, or recreation? What will happen to the land once it's transferred? What effects may THAT have on surrounding areas, local communities, and so on?
  
  
• What do you need to know to answer these questions? Do you have the information? Can you afford to get the information?

You also may find that the agency's CX checklist, or whatever device the agency uses for screening its CX decisions, doesn't work very well, or even misleads you. For example, does it ask only about impacts on places INCLUDED in the National Register of Historic Places, and not about those that are ELIGIBLE? Or does it ask about eligible properties too, but not give you any guidance about how to find out which are and which aren't?

In thinking about what you might do to address challenges in applying the agency's procedures, assume that you can't change the procedures. What else can you do? Can you frame a convincing argument based on the logic and language of the procedures? Can you bolster your case by referencing the requirements of other laws -- for example Section 106 of NHPA?

In imagining yourself as an outside party, your first problem is going to be to find out about what the agency is doing, since its CX decisions don't require any particular review. You might consider first what you'd do if you heard about a possibly destructive project and wanted to inquire about it. Would it help to ask where the project stands in NEPA review? What if the agency just says "It's categorically excluded?" What can you do? Next you might consider what you might do programmatically -- supposing you're the SHPO, or a local cultural group. Can you think of ways to make sure you get to review and critique CX decisions routinely?