Recycling of Tsunami Deposits by Soil Modification and Heavy Metal Immobilization Treatment for the Disaster Waste Management Project in Kesennuma

Abstract

Due to the 2011 off the Pacific Coast of Tohoku of March 11, 2011, a large scale tsunami hit the Pacific coast area of the Tohoku and North-Kanto Regions, Japan. As a result of the earthquake and subsequent tsunami, approximately 900,000 tons of the tsunami-related deposits were left in the flooded area in Kesennuma city, Miyagi Prefecture. Since they were expected to be certainly recycled as embankment or backfilling materials in the prospective restoration and reconstruction works, proper treatment and management were essentially required for the tsunami-related deposits. Additionally, rapid completion of the treatment project was also important for the local residents to preserve living environment and improving public health. Thorough our laboratory experiments and a field demonstration to select soil modification materials for the tsunami-related deposits, both gypsum-based and lime-based materials were effectively accelerating dry sieving process. A part of the tsunami-related deposits contained naturally occurring heavy metals and required an additional treatment for immobilization. Elution concentration of arsenic and fluorine could be controlled stably below their criteria by using magnesia-based material. This paper summarizes the outline of the treatment of tsunami-related deposits and describes the geotechnical properties of recycled geomaterials in Kesennuma treatment area.

Disaster waste management after the 2016 Kumamoto Earthquake: A mini-review of earthquake waste management and the Kumamoto experience

“…In addition, because of the damage to the Fukushima nuclear plant, the materials for recycling also had to be monitored for potential radioactivity (United Nations Environment Programme, 2012), as it was found that the incinerated waste residue around Fukushima resulted in increased radioactivity (associated with radiocesium) (Saffarzadeh et al, 2014). Soil contaminated by tsunami-related deposits mainly contained gypsum-and limebased deposits and naturally occurring heavy metals and required proper treatment with appropriate techniques for separating the contaminants or immobilization of the heavy metals to preserve the living environment and maintain public health (Ohta et al, 2016;Uno, 2015). The rotatory crushing and mixing method can be applied for the separation, crushing, and removal of disaster waste and restoration of farmland with soil (Nakajima et al, 2015).…”