PROBLEM TO BE SOLVED: To make drain water smoothly flow for a long time of period by preventing sand and refuse (straw cuttings, wood tips) from clogging into holes and inflowing into an underground porous drain pipe used for drying a playground or park in which a paddy field water or rainwater has infiltrated. SOLUTION: The whole face of an underground drainage pipe 11 having many holes 12 is covered with a sheet of nonwoven fabric 13 made of a chemical fiber, and inflow of sand or refuse into holes 12 and underground drain pipes 11 is prevented by the sheet of the nonwoven fabric 13 made of the chemical fiber. The drain pipe with holes filtrates water and makes cleaned water inflow into the underground drain pipe 11, to remove the refuse. COPYRIGHT: (C)2004,JPO
