Establishment of underdrain maintenance procedures (FHWA-OK-95-04)

Project #2183 analyzed the condition of underdrains and developed a method of classifying, maintaining, and, when necessary, replacing underdrain outlets. The project encompassed every region of Oklahoma and many different climates and geological conditions. The most common seepage conditions occur where a permeable geologic layer, such as sandstone, overlies a relativel y impermeable layer, like shale. Various drain pipe types and sizes were included in the original survey. The outlet maintenance demonstrations were concentrated in those regions where the procedures will be most often applied. Equipment specially procured for the project included a pipe inspection video package, and a high pressure rodding system (jetter). The primary focus is on the maintenance of pipe underdrains, although some recommendations regarding design and installation are included.Final Report May 1991 - May 1995N