Bill raises an excellent question in the post above.
The last house I lived in had a septic tank, and the field lines were at a higher elevation than the tank, so there was a pump in it to pump the effluent to the field lines. Is this what you're referring to in your original post?
Interesting thing on septic tanks: they are living biological things, and when they are healthy and full of the good bacteria and enzymes, a septic tank
never needs to be emptied by a pump truck. Healthy septic tanks chew through and dissolve the solids. In that last house I lived in, 10 years and I never had it pumped. Growing up in my parents house, 30 years and it was never emptied by a pump truck. There are two keys to achieving a healthy septic tank, and 1) is to not put things down the drain that kill bacteria, like bleach, chemical household
cleaners, antimicrobial soaps, etc. 2) dose a septic tank regularly with a septic treatment. I use Bio-safe One septic treatment in my new house I currently reside in, and I did for the ten years in the previous house. I'm not trying to make a sales pitch, just offering the name of what I've been using that has given me reliable and effective results. Hope this helps!!