a bit of advice.
is it truly a private road?
is it a prescriptive road?
does it have any deeded or recorded municipal ROW, causeway, or utility easements?
Is it in a water management district that manages water runnof and drainage in swales?
( yes.. they get to tell you how to handle runnoff and drainage on your own property!! )
In some areas, you can have a piece of land, and if you install a non permeable surface on it, you even have to be permitted for drainage reasons. ( concrete pad, roadway, driveway.. asphaltic concrete.. etc.. )
just sayin... check before buying and burying

hate to see you buy some culvert.. dig it.. set ip.. pour some mitered ends and splash pads with rip rap or energy disipators, and then have the county man drive buy and 1, fine you for building in a ROW, 2, cite you for doing work with out proper permits ( citation is usually 2x cost of permits! ), and 3, make you rip it out either because it was not inspected during work, or because it really just can't be there according to law. Could do ALL 3 to ya. so check twice.. cut once.
just some friendly advice...
soundguy