It would be interesting to see (1) how many communities actually have a comprehensive master plan, (2) how many community leaders have fully read their comprehensive master plan, and (3) how many comprehensive master plans are collecting dust on a shelf somewhere? Typically, the comprehensive plan involved charettes and/or community meetings to gather input from the citizens. In fact, the "task forces", "focus groups", and committees that formed during the comprehensive planning efforts are perfect starts to developing a "Brownfield Resident Advisory Committee" (BRAC) for your self-sustaining Brownfield Program (More thoughts on "self-sustaining" in a blog after Oct. 15th deadline). Also, hopefully, some positive, productive community leaders emerged during the comprehensive planning efforts. Their energy and ideas will help sustain the brownfield revitalization effort.
Finally, READ the plan. With your newly acquired knowledge of the concept of "brownfield redevelopment", you are better equipped to identify the areas needing assessment or cleanup assistance. Often, the urban planners who developed the comprehensive plan don't use terms like "brownfield". Look for key terms like "blight" or comments about the high level of un-leased commercial space in certain areas of town. A quick drive in those areas may result in the identification of a number of closed dry cleaners, gas stations, pest control shops, or auto service shops.
Cite the good work that you've already done with your comprehensive planning efforts. Get your urban planning consultant that generated the report to send it to you in a word processing format so you can do a little cutting/pasting. If he/she is reluctant, remind him/her that the comprehensive plan may need updating to include a brownfield component.... His/her demeanor may then change.
Good Luck!