Not a nuclear dump but a closed landfill that has been capped and is currently venting for the next xx years.

Knowing things like this is why you should ALWAYS use a good local realtor. You may decide that it isnt an issue to you but surely you should have known about it.

FWIW the other listing is priced nearly 100K over the current market value. Long time seller has plenty of equity. Go get her if you please.