I second Don's comments. Most CERCLA sites are not brownfields. If you can go through the brownfield process as per Steve's post (great post and info) that may well work but it is not easy or cheap if you have to put up the $ as Steve noted. Most sites don't work that way as often the current owner doesn't want anyone doing tests for which he may be liable and no one wants to be a PRP if EPA or a state DEQ becomes involved. Steve's post was how to do it from a redevelopment angle. Unless I knew in advance that a brownfield was available and paid for by someone else then it should be approached from a liability avoidance point of view.