Publication of Handbook for Handling Rocks and Soils Containing Naturally-occurring Heavy Metals at Construction Sites
Fig.1 Cover of the Handbook
Fig.2 General flow of response actions
to surplus soils containing
naturally-occurring heavy metals
during construction work
and hammer strike test
Fig. 3 General flow of response action
to acidic surplus soils
during construction work
Fig.4 Slope with the surface color
turning brownish without vegetation
as a result of acidic water
Fig.5 Details of the survey that
matches each project stage
Fig.6 General flow for evaluating rocks
and soils containing naturally-occurring
(When the competent local government has
any relevant ordinance, the competent
environmental division or bureau has any
relevant directions, or conditions for
receiving construction surplus soils are
established, the above flow may not apply.)
Rocks and soils contain naturally-occurring materials that are toxic to the human body (such as heavy metals*), although in minute amounts (Table 1). Accordingly, as people have become increasingly aware of the need to protect the environment, the Soil Contamination Countermeasures Act was enforced in 2003. This gave rise to increasing demand for a way to evaluate the impacts of excavated rocks and soils containing naturally-occurring heavy metals and other substances (hereafter "surplus soil containing naturally-occurring heavy metals") on the environment and measures to mitigate them. In response, the MLIT compiled a draft version of the Manual for Handling Rocks and Soils Containing Naturally-occurring Heavy Metals at Construction Works in March 2010. Later, the industry wanted an explanatory book for field engineers, and so the PWRI, which was deeply involved in formulating the manual, and the Ground Pollution Response Technology Review Committee of the Public Works Research Center edited and published the Handbook for Handling Rocks and Soils Containing Naturally-occurring Heavy Metals at Construction Sites (Taisei Publishing Co., Ltd.) (Fig. 1).
Structure and Contents of the Handbook
The Handbook was written for field engineers who handle surplus soil containing naturally-occurring heavy metals for the first time. Table 2 shows the structure of the book.
Chapter 1 describes the need to appropriately handle not only surplus soil containing naturally-occurring heavy metals but also surplus soils that acidify in contact with air and water while being excavated (hereafter called "acidic surplus soils" in this Handbook), as well as a general explanation of the typical flow of response actions (Figs. 2 and 3).
Acidic surplus soils are not required to be managed by laws or regulations including the Soil Contamination Countermeasures Act. In practice, however, evidence of various problems has appeared including the death of fish due to acidic water, browning of slope surfaces, or no growth of vegetation (Fig. 4). Therefore, it is necessary to cope with acidic surplus soil.
Chapter 2 describes the types and distributions of surplus soils containing naturally-occurring heavy metals and acidic surplus soils, the risks posed by such surplus soils to construction work, and the basic policy on toxicity and the need to cope with surplus soils. The chapter also explains that different legal systems apply to the handling of surplus soils containing naturally-occurring heavy metals depending on the location, mode of occurrence, history of discovery, and disposal site.
Chapter 3 outlines the basic flow of mainly voluntary surveys (Fig. 5) and suggests a flow of steps to judge whether or not there is a need to respond based on the surveys and tests conducted in each stage (Fig. 6). The chapter describes the purpose and specific contents of the survey to be conducted at each stage and major points to note.
Chapter 4 arranges in order general response measures by mode of occurrence and location of use of surplus soils. The chapter also describes important notes on predicting the impacts on groundwater, measures to take during construction work, monitoring, and post-completion management.
The references section provides useful information for practicing engineers including case examples of evaluating the elution characteristics of surplus soils containing naturally-occurring heavy metals. It also describes various testing methods, examples of measures taken, examples of judging the need for measures, and a list of standard values.
The handling of surplus soils is expected to be a major factor that determines the construction cost and period of large-scale construction projects in the future. We hope this Handbook will be of help in the handling of surplus soils.
* Note: Heavy metals are defined herein as those hazardous substances designated by the Soil Contamination Countermeasures Act, specifically including the following substances contained in natural rocks and soils: cadmium, hexavalent chromium, mercury, selenium, lead, arsenic, fluorine, and boron.
(Contact: Geology Research Team)