I had a rather heated debate with a home owner the other day regarding the performance of his perimeter drain tile system for his house. He was most upset with the performance and wanted to know why the drain tile system only seemed to work for about 7 to 9 years. I told him that typically the gravel and drain tile typically become clogged with fines after approx 8 years and a new system is required. I also told him that you could possible flush the system from the clean out points which might give the system a few more years of life. The house has a standard basement and the surrounding grade generally sloped away from the home. I know some drain age systems use a geotech fabric, but I have found that this does not really help that much.(just adds costs) The soil is a typical variety of topsoil/stiff clay overlying sandy silt and clay. The rain fall is quite heavy in this part of the country. The drain line has a downward slope away from the house to the city connection.
Have I missed something here?
Any comments and usefull insight would be greatly appreciated.