its about 10' deep and 30' in diameter.I read to fill it with clay soil, but was wondering if there were any environmental/permit considerations.

@Bennet Sebastian @Clay Smith Thanks for the advice.

Clay Has 9 , Flagler has 5 but the coun>ties with smaller amounts have their Lamds available list online.

The plumbing could have lead supply lines and galvanized supply lines, and the waste lines could be clay, "Orangeburg" (Black coal-tar impregnated fiber piping), and even cast iron waste can develop cracks especially if the lines go unused for long periods.

Turns out the cast iron under the basement needs replacing along with the clay going from the street to the house needs replacing too.

Vrbo.com my bad..typing on tablet with predictive text:)thanks, Matt

If you do need to go 20 or 25% down (outside of owner financing you would), your CoC will likely be below 10% (sorry, on a tablet and don't like flipping tabs to do the real math).

The first book I read was "Flip-How to Find, Fix, and Sell Houses for Profit" by Rick Villani and Clay Davis.  

My technology is a little outdated,  I still own a flip phone and just got a tablet last year!

Many are on clay soil which gets a lot of settling.