If I back out, my lost will be the attorney fee, home inspection cost($600) and oil tank search ($300). I don't know how much the atthorney will charge me but it will not be more than $900 -- The agreement with the attorney is $900 but he will not charge me the full price unless we close the purchase.
In terms of renting, this is next to a university and they will seal the sidewalk while the periodic monitoring is going on so there should not be an impact to renting the house.
My biggest headache is the uncertainty about this project -- will the seller do as said to take care of it? What if more work needs to be done after 2 years monitoring??, etc