Hi, I found an apartment that I love but in the bulding there is a oil tank with soil contamination.

Asbestos contamination for extended periods has been proven to be very bad, health-wise.

YOU, can also do this type of inspection so that you know you DON'T HAVE CONTAMINATED FILL DIRT. 

Does it have environmental contamination or title issues?

You really cannot develop a good estimate until the scope of the contamination is fully understood. solvents are very tricky. i have never seen a solvent cleanup that came close to pre-cleanup plan estimates.  

Proper steps need to be followed so you don’t contaminate the house with lead dust and chips.

TTHM & HAA5s are carcinogenic but the risk is minute; far more people have been killed by drinking contaminated water than by TTHMs and HAA5s.

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.