In the construction industry, where large quantities of soils are dealt with for excavation, cutting, filling, embankment, and land reclamation, various efforts have been made to promote the proper utilization of these soils so that the environmental damage they cause will not be fatal. However, there is still room for further utilization of these soils due to their diverse composition and other beneficial factors. More scientific knowledge, technology development, and research on how to implement them into social systems is still definitely needed. This manuscript reviews the status of treatment and utilization of excavated soils and discusses technologies and systems for dealing with soil contamination, geogenic-contaminated soils, construction sludge, and soil-waste mixtures, topics which have become important in recent years.

Improper disposal of soil has become an issue. Some disasters, such as the debris flow disaster in Atami in 2021, have caused serious damage toh uman lives and property. Improperly disposed soil is considered tob e part of the soil that has not been used effectively, and further promotion of effective use of soil will lead toa decrease in the number of cases of inappropriate disposal. The Ministry of Land, Infrastructure, Transport and Tourism (MLIT) has been promoting the effective use of soil through the use of the Construction Soil Information Exchange System, etc. However, with the legislation of the New Fill Regulation Law and other laws and regulations, the effective use of soil will be increasingly required in the future. Therefore, MLIT will continue tovigo rously promote and support the efforts of contractors through the accounting of appropriate soil disposal costs and the promotion of the designation of the soil disposal site in the procurement process. We hope that all parties concerned will actively promote the effective use of soil.

The construction sector plays an extremely important role in accepting recyclable materials that are generated in large quantities. Some recyclable materials contain harmful substances, albeit in very small amounts, which makes environmental safety evaluations are necessity. Efforts related to the environmental safety evaluation method for recyclable materials have changed from the time that soil leaching tests were applied mutatis mutandis to nowadays that the evaluation methods are distinguished between recyclable materials and soil. The basics of environmental safety quality and the evaluation methods of recyclable materials have been established.We have made steady progress in revising standards and guidelines for each type of recyclable material. Recent times have prompted the necessity of establishing more rational evaluation methods and management methods.

Rocks and soils may contain small amounts of heavy metals in their natural state. Rocks and soils excavated in large quantities in construction projects, such as tunnels and cut slopes, have long been used as effective resources for embankments and landfills. On the other hand, with the enactment of the Soil Contamination Countermeasures Act in 2003, there has been a social demand for environmental safety assessments and necessary countermeasures for rocks and soils containing naturally occurring heavy metals. In this paper, we discuss issues related to the handling of rocks and soils containing naturally occurring heavy metals in public construction works in Japan. In addition, we introduce the contents of the Ministry of Land, Infrastructure, Transport and Tourismʼs “Manual for Countermeasures against Rocks and Soils Containing Naturally Occurring Heavy Metals in Construction Work (2023 edition)” and touch up on future prospects.

Improper disposal of contaminated soil, landfill and embankment caused by soil mixed with waste, and excavated soil (such as embankment collapse disasters) were being handled under the sediment ordinances of municipalities in the Kanto region and other areas where these problems were becoming apparent. However, since May 26, 2023, a new law enacted in response to the massive mudslide disaster in Shizuoka Prefectureʼs Atami City in July 2021 has made it necessary to adopt uniform standards nationwide. This paper summarizes the new laws and regulations, and provides the authorʼs personal opinion on how municipal ordinances can respond.

There are still some cases of inappropriate mud recycling on the utilization of construction sludge. The main reasons for this are that the line between construction sludge and soil generated from construction is blurred and its treatment as waste is usually disregarded. Also, recycling designs that provide sufficient attention to ensuring product quality have not yet been implemented. In other words, when recycling construction sludge, it is essential to take initiatives based on waste/recycling governance, to strictly apply reproduction methods, and to properly evaluate costs. In order to plan and implement a construction sludge recycling plan, the establishment of applicability standards which include applicable laws and regulations/environmental standards is necessary, along with the proper selection of treatment technologies, construction systems, and quality control methods that fully take these standards into consideration. In this paper, some examples of projects and issues surrounding the activation of construction sludge recycling are introduced.