| The excavation sites for East Hokkaido highway construction、 (a) tunnel is located east area in Hokkaido. The geology of the sites is marine sediments composed of alternating beds and mixed rocks facies of sandstone、 shale、 mud stone and silt-clay.In digging these tunnels、 the digging soil is reclaimed in the landfill site.The landfill site is in the foundation of highway embankment.The blue part in the photograph is a seat to protect the soil all over the construction cancellation period.A blue part in the Picture is a seat to protect the soil for the construction discontinuance period. The directionality of measure is the follows.[*]The natural soil contamination has 2 main problems.[*]One is a huge amount of contaminated soil、 another one is contaminated soil contained large rocks.[*]Conventional major countermeasures are difficult and unrealistic in the case of natural soil contamination.[*]high cost、 no space、 low workability for rocks.[*]So、 the adsorbed layer method was designed instead of conventional measures referring to Permeable Reactive Barrier (PRB). [*]PRB is passive intervention remediation technology for groundwater pollution.[*]The concept of risk management is different between conventional measures and new measure. The countermeasure of heavy metals should originally occur as risk management. But、 the former has aimed to assume abandonment to be a means、 to remove the pollutant from the site、 and to dispose it to other places、 meanwhile the latter manages the risk to use contaminated land and soil. |
