If I understood correctly, this water seepage is around or under the sewer pipe at the spot where this pipe penetrates house foundation. Since I can’t see the problem and you didn’t describe in detail how it looks I’ll just list some possibilities.
The foundation structure at the sewer pipe penetration is usually slightly weakened by that pipe hole which sometimes results in crack formation (below and above the pipe) and water leakage. To evaluate and fix the crack you’d need a waterproofing company which would, in most cases, use epoxy injections to seal the crack. Common warranty on such repairs (use some established brand such as US Waterproofing or Perma-Seal) is 10 years + or lifetime.
Sometimes there might be a gap around the pipe which also allows ground water to seep through. The same procedure as in #1 would take care of it.
In both scenarios I assumed ground water as a source of seepage in which case only the foundation waterproofing contractor would be required. However, I’ve inspected many homes where there was a plumbing issue responsible for water penetration as well.
Depending on the pipe’s material and how was the pipe’s exterior surrounding area (soil outside of the foundation) prepared during construction process, there might be sometimes too much stress on the pipe itself which could cause it to crack right before it enters the foundation. House foundation and surrounding grounds with pipes buried underneath always shift at slightly different pace.
Deteriorated, rotting, corroding pipe could be responsible for a leak as well. If this house is occupied it shouldn’t be difficult to determine if leaking water is from the sewer or clean / ground waters.
Another sign of an underground plumbing leak (must be significant and prolonged) is sometimes a distortion (dipping) of the landscaping surface directly above the sewer pipe (it’s just a possibility; don’t start digging when you see something like that).
Another possibility; sewer and water supply line sometimes run very close to each other and supply line could be leaking as well. Plumber would be needed to investigate such thing.
The easiest way to find out the condition of this sewer line, without digging, is to hire a plumbing contractor equipped with a camera which can be inserted into the pipe. He should be able to see any problems from within the pipe; cracks, displacement, separation, etc.
Personally, I would start this process by calling only the waterproofing company for evaluation unless the leaking water is contaminated, might be sewer leak related. In that case you should seek a plumbing contractor’s advice as well.
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