Hi everyone,
We've recently finished our basement, which includes a full bath that utilizes an indwelling macerating pump for effluent disposal. (We had the contractor rough in all the plumbing before the concrete was poured, etc).

Everything works well, until it rains heavily. At that point, we frequently get noticeable bathroom smells in the house which clearly come from the (supposedly sealed) container that houses the pump. The vent stack and waste lines coming from the pump have flanges that go through the container lid, and my husband sealed them with silicon after the plumber got everything hooked up.

Does anyone have a suggestion on how to fix this, or what the problem might be?