[dad911]

Justin has it right. I don't know about your area, but since it was built in 88 you have PVC pipes and probably a concrete tank, which is much better than cast iron or clay tiles and a steel tank....

Problems to look for would be proper pitches on tank & pipes, pump tank to make sure there are no cracks (I've seen cracked/leaky tanks that the water never makes it to the septic field, it goes down to the house drain!)

An engineer would(should) pump the tank, camera the lines, and check elevations to make sure the system was installed correctly. Then flood it with water and make sure the distribution field can accept the water at the right rate.

Again, I don't know about your area, but here in NJ the County Board of Health would have the septic designs on file. It would be good if you can get a copy of them. It would also list the designer (probably an engineering firm).