| 摘要 |
PROBLEM TO BE SOLVED: To surely seal sludge including a harmful substance, without stirring up the sludge, thickly accumulating a soil covering material, or using an expensive impermeable sheet. SOLUTION: A permeable civil-engineering sheet 4 is laid on a soft polluted sludge layer B which is accumulated on the bottom of water, so that the sludge can be prevented from being stirred up; after that, the soil covering material, which is turned into slurry through the use of a discharge pipe 12 held by a back hoe 10 on a soil covering ship 11, is accumulated on the sheet 4; and a soil covering layer C is formed while preventing the mixing of the sludge and the soil covering material. In this case, preferably, materials, which include at least 20 wt% fine-grained fraction with a particle diameter of 74μm or less, such as mountain soil and surplus soil in construction, coal ash, blast furnace slag, activated-sludge molten slug are selected as the soil covering materials. The soil covering materials can reduce construction costs because they are far more inexpensive than sand, and the outflow of the harmful substance can be surely prevented because the fine-grained fraction adsorbs a pollutant such as dioxin. COPYRIGHT: (C)2005,JPO&NCIPI
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