Sewer Treatment Plant in apartment complex

[Josh Carlegis]

Hey guys, looking at a deal and ran across something I have not seen before.  It is being sold in 2-20 block sections and you can buy an on site sewer treatment plant as well.  They are vacant and need full rehab.  Is the STP required there for a particular reason like there is no sewer and you cannot put septic?  It is close to a lake so maybe low area wont perc?  Thanks in advance for any help!