Not sure if I am posting in right forum, Sorry if it wrong. I have been working on a customers landscape installing a few walls and some walkways. He came to me and asked me what I could do for drainage in his back yard. His yard is a corner lot and is pretty small. It is square shaped and is the basically the catch basin for all the yards up the hill from him. Now the house is a walk out basement and the grade slightly slopes towards the house. No way of regrading. Customer says yard is constantly wet even in dead of summer. He possibly thinks there is a natural spring. When I walked in the back yard my foot sank down to the ankle. I was thinking of putting some french drains in and connecting to a underground sump system and pumping it into the sewer, Which is slightly up hill and 40 feet away. My problem is I cant find a basin with a solid lid that will withstand enough weight not to break in if walked on. Plus I have never installed one before and would appreciate any tips or input that you guys can help me with.