We live in an area of natural springs with a high water table and silt content. Our basement has a 17yr old full perimeter french drain system. The system does not use pvc pipe but instead has a "black tubing with interior & exterior ridges. Anytime we have 2 or more inches of rain we have water seepage at one end of the basement...The question is, is it possible the drain system tubing over the years has become partially blocked- and cannot handle the excess water from heavy rains?? The excess instead of flowing into the sump pit and being pumped out seeps into the basement? Second question other than digging up the existing drain tubing, if it is plugged can it be cleard??
The black piping you are referring to is called ADS or Advanced Drainage Systems and is used universally around the world for drainage. It is the best possible pipe that could be used for the purpose we're discussing. If installed correctly (pitched/sloped correctly and preferably without a filter over the pipe - reason: do you know of a filter that exists that doesn't have to be changed?) it's designed to be a self-cleaning pipe meaning the water flowing through should clean out sediment buildup or clogs. If it is installed level and not covered with enough gravel it will eventually clog. So not only is it possible this pipe is clogged but very likely. The only way to clean these out without digging up ground is if you have some sort of cleanout setup by builder or if the pipe comes out somewhere and drains to daylight. I don't think this is case b/c you made mention to drain pipe coming into your sump pump likely meaning they couldn't grade it to daylight and had to drain into sump pump which is only other option. If you would like to discuss more about this problem you can contact me at email@example.com and I can gladly explain more to you as I have helped/fixed problems of many others.