The organic sediment moves with water flowing in estuary. It is carried to the river with flood tide from river mouth, and settles on the riverbed at a tidal flat. The organic sediment settled there causes the environment deterioration and loss of waterside scene value. Then, the environmental quality improvement technology was proposed using fly ash for consolidated sediment.
We established the construction technology for environmental improvement at riverbed covered by organic sediment. The infiltration-pillar was constructed as a method of supplying oxygen into consolidated sediment by the water movement in the pipe with the ebb and flood tide. After infiltration-pillar was constructed, the effect of the environmental improvement decreased the sulfide and the ignition loss in the sediment, and it was confirmed to decrease the nitrogen in the pore water.