There is probably little or nothing you can do:1) You probably--almost certainly--do not have the "standing" to challenge the county's actions on the grounds that there might be PCBs or some other danger, since the county's actions do not affect *you* in that regard--you're living near that land anyway. As a general matter, only someone who is directly affected by an action has the right to challenge it.2) It is sometimes possible to challenge a property use on the grounds it creates a "nuisance," but a "nuisance" has a specific legal meaning of a use that is generally unwelcome or undesirable in society, or whose side affects at least would be generally considered unwelcome or undesirable. There is also a societal balancing often--the interests of society or the community at large are considered as well. Even if you don't want a park nearby, it is very unlikely the community or a judge would consider a park to be a "nuisance" use; typical nuisances including concrete plants or slaughterhouses in residential areas, where there is no community gain and the locatio is clearly inappropriate.If this matters alot to you, you should of course consult with a real estate attorney who can evaluate the situation in detail and depth; you need to be prepared that it is unlikely, however, that you can stop this. For what it's worth, usually the installation of a nearby park actually raises property values; if this happens, you may at least be in a good position to sell and move elsewhere, if you like.