Abstract
Penetration experiments were carried out for a period of over two years at an experimental field located in Kusatsu City. The field was divided into two tanks and each tank filled with different types of soil. Polluted water discharged from the road surface was supplied to the field during storm events. The effluent from the field was composed of Surface and Infiltrated flow. The flow was gauged at three points and water sampled for quality analysis. In order to analyze measures against clogging, soil in one tank was replaced to investigate the recovery of soil contents, penetration efficiency, and purification efficiency. The other tank was researched continuously for 26 months to analyze the change of purification efficiency with precipitation characteristics and the continuous use the facility. Sustainability was analyzed by modeling long-term mass balance in the facilities using water quality data (COD, N, P and SS) and comparing the results with actual measured data of the change of pollutants in the soil. The facility achieved high pollutant removal efficiencies of between 50% - 90% during the survey. Simulation results using water quality data compared well with actual measured data of change of pollutants in soil.
