Subscribe or Renew Membership Subscribe Renew

Slab over Septic line

ryno's picture

I plan on building a garage next summer.  In trying to lay out how the garage might sit, I am faced with possibly placing the slab over an existing sewer line.  It is the line that runs from the tank to the leachfield.  About 24 feet would be covered by the slab.  The line is at least 4 feet below grade.  Is this a common practice?  The only thing I am terrified of is having to ever dig up that sewer line, though it is nearly new.  Thoughts?

Around here the first (post #207159, reply #1 of 3)

Around here the first question that would be asked is whether you should be building a foundation on previously disturbed soil. Opens up a big can of geotechnical issues.

But they are valid issues! I built a mere 10' X 10' entry over disturbed soil that I thought I had compacted the carp out of, but the darn thing sunk two inches in two years. And that's just a covered entry, attached to the house but not sharing the same foundation.

Contingency Plan for Septic Replacement? (post #207159, reply #2 of 3)

I sure would like to have a good contingency plan for replacing that septic line someday.  If you live in an are which perks well, if should never be an issue, but some places are a problem and people need to replace teh systems.


Probably not "common" (post #207159, reply #3 of 3)

Some codes/sewage regulations wouldn't allow it.  If the line is 4' deep, Sch. 40 PVC, and properly bedded, it may never be a problem.  If the construction causes the pipe to bow down (i.e., create a low spot in the line) that length of line would be prone to clogging.  Theoretically, no solids leave the septic tank, but in reality trash will sometimes make get out of the tank and cause clogging downstream.