I Just got a french drain put in to solve a minor water problem. Now I have no water in the basement but the new concrete gets damp and changes color where the drain is. The water doesnt seem to bleed into the old concrete. Is this something the contractor did wrong? I know the new concreate is thinner but should it be soaking up this much water. This creats a problem because I wanted to carpet down there can I still do that if I put a layer of 6 ml plastic under the carpet?