Sewer line "tap" through my property

[ode2joy]

I am in the state of Illinois, and recently had a gentleman buy the house next to mine. He "flips houses" for a living, and is busy renovating the place to sell off. He claims he found out only after having purchased the lot that the existing structure was on a septic system, and now due to the renovations he's doing he will have to tie into the city's sewer line since he is within 75 feet of it. His two options as he's been told are as follows:

1) Tie into the existing sewer line under the street directly in front of his property, which happens to be a State highway, or
2) Trench through our property to gain access to the sewer line under the street my property sits on, which is a city street.

My guess is that option 2 is a much less expensive option, as he's asked our permission to go that route (despite a much longer distance compared to Option 1), offering to regrade/reseed the area once he's finished. What kind of implications would this have or what things should I consider and keep in mind before making this decision? I don't want to be an "inhospitable or overly concerned neighbor", but I have no idea about anything like where liability lies if something happens with that sewer line, how this would effect the value of my property, etc. Any suggestions would be greatly appreciated.What is the name of your state?

 

[jro12]

easement

at least in utah you would have to give them an easement to cross which would give them the right to access the line for repairs so 10 years down the road if they have problems with the line your yard gets dug up again. I have been an excavator for 15 years and have never had anyone let us go through their yard we always have to go into the street in front of the house. Not that they wouldnt if we were willing to pay them an outrageous fee for the easement.