Thanks for the information @Sandy Hu

The first thing I think you should do, is have a soil test done.

all you have to do is look at pictures or video of Super Strom Sandy in New Jersey. 

They are mostly all in Anderson, but we have a few scattered throughout Townsville, Clemson and Sandy Springs.

Yours will vary depending on the site soil conditions and legal requirements in your state.We removed the old trailers and brought in newer ones.

Our clay soil moves all over the place and the amount of settling and resulting repair can be extreme. 

Those are some pretty serious issues (foundation, sounds like, combined with the nearby lake and septic issues sounds like there may be fundamental soil issues.)

Then you have to deal with environmental issues, soil issues, etc., which can impact buildability (is that a word?

With this disclosure, you may have to undertake a Phase I Environmental Assessment - your lender or insurer may insist on it.We had a very similar deal on a multi-family a year ago - when the Phase I and some soil sampling came back strongly indicating remediation, we - and our lender - insisted on placing a substantial portion of the purchase price (30%) in escrow to cover remediation costs.

It seemed like a great deal, and there's only a few lots left not built out.In doing our due diligence, we found out that since the original development, the City has decided the soils in the area are going to require more stabilization, and aren't even sure what they will require.