The under board of HW-103 drainage plant is makes by high impact polystyrene (HIPS). Can resist the high pressure, will not distortion. This kind of character not only can endure the concrete weight and its load capacity, but also may endure inevitable external pressure and the impulse during the construction period, like the vehicles, worker's trample and the pouring of concrete momentum and so on (must under the condition of covering 30 centimeters soil layers). Maintains under board not to distort for a long time, thus may maintain the original displacement. 　　The geotextile membrane guarantees the channel not to be blocked by other substance like returned earth and concrete. 　The HW-103 drainage plant not only in function, but also in economic is efficiently than other traditional filter. HW-103 is suitable for the bulkhead, the basement, the tunnel, the pitch, the flowered trough, the platform and so on. 　　HW-103 drainage plant only have the function of draining water, it is used wildly in retaining walls, basement, tunnel, slope protection, highway roadbed. (Details sees construction handbook)