Building a Playground over a Leach Field?

For those whom are familiar with septic tanks, the leach field is basically a long draining area for your sewage (unlike city areas which simply have a sewage line)…

Anyway, I would normally not be concerned about a simple playground or kids running around our leach field, except…

I want to build a large playground in our yard (more like a raised deck that spans 8’ X 16’ for them to have a small ‘treehouse’ like feel). The only spot that it will fit places it right over the edge over the leach field. I thought it was going to completely clear it until I dug down 27" and hit the protective top layer and then stones…

I need to build 6 piers that drop below the frost line (about 36") that will hold this elevated structure…

While I know that messing with the leach field is never a smart idea, I was wondering since I’m not actually on any of the main drainage pipes (they’re a few feet deeper into the yard), would I cause major harm to my septic system by building on the very edge of the leach field…

The field measures 42’ X 20’ and I’m resting on about the edge by about 1-2’… as a result, it seems 2 of the 6 piers would intersect the right edge of the leach field…

Could I remove a 10" diameter section for those 2 piers, as long as it wasn’t near the main drainage pipe?

I may have some small leeway in moving the post piers away, but only a few inches at best…

I have a feeling that I should probably play it safe, but figured I’d ask any experts if they’ve found/know any ways around my dilemma…

Any suggestions are appreciated!

you don’t want to compact or put weight on the area above the trench. you could destroy then functioning of that trench at that point. a pier is a lot of concentrated weight which is the destroyer of a field.