1.)Yes if the correct info is give to the owner about the type of system that they have and how to operate and maintain it.
2.)No, it is not know. If you mean that after the owner is instructed as in above that you do not touch the system for 10 to 15 years,no the system will need to be pumped every 3 to 5 years. If the system is the basic septic tank with a D-box and wit pipe in rock laterals, the tank will still need pumped every 3 to 5 years. If there is any kind of secondary treatment after the septic tank, that portion will need to be looked at every 6 months, depending on how unique it is. (Septic tank with an outlet filter, pumping chamber with pump pump controls and alarms for a LPP lateral, ATU, single pass or recirc.sand filter, drip distribution, constructed wetland, rock filter, modified constructed wetland, trickle filter, D-box that can be maintained from the surface, ect.) Do a search with any search engine on ” onsite septic system” and you will find out more than you ever wanted to know about onsite systems.