There are now voluntary cleanup or brownfield programs that incentivize  purchasers to redevelop contaminated properties.

Many methods to get results however without combining them with a complete tear out of all of the worst effected areas the smell will return on the first humid day in the summer.Eliminating cat pee is a combination approach part of which will be to remove the most contaminated areas.....sub floor, drywall etc.

It's heavier than water, so will sink to and then through the water table, contaminating it in the process. 

Killz works well but you must get to all contaminated surfaces.

Environmental Assessment:Have any hazardous materials ever contaminated the property?

For instance, if you pay for the bills of LLC #1 out of LLC #2's bank account, they have been contaminated and it opens you a lawyer arguing they are the same company and the assets should be fair game as you operated them as a single entity swapping funds between each.   

Outside my realm.... but aren't some places (or at least in CA) zoned industrial in part because of the contamination?

Hi Michael,     I grew up in Lone Jack and all my family is still in the Kansas City area, those who haven't followed me to SWFL.. lolI own a mold remediation company in SW Florida, The best thing to do with the drywall depending on the amount contaminated is to remove and replace it.

A remediation company came in to the condo to clean and cut out the contaminated materials.  

The issue is to confirm if the soil is contaminated and the extent of the soil contamination.