Regulations to prevent groundwater contamination (structural standards)

Regulations for the prevention of groundwater pollution based on the Water Pollution Control Law

Last update date April 1, 2024

Effective regulations to prevent groundwater pollution

In order to prevent groundwater contamination by harmful substances listed in the following table, regulations have been established in the Water Pollution Control Law that require compliance with standards, periodic inspections, and records and preservation of the results have been established in the Water Pollution Control Law (enforced on June 1, 2012).

Structure standards
Periodical inspections
Recording and preservation of the results of periodic inspections

List of Hazardous Substances

Table Hazardous Substances (Article 2 of the Ordinance)
No.	Hazardous Substances
１	Cadmium and its compounds
２	Cyanide compounds
３	Organic phosphorus compounds (limited to parathion, methylparation, methyldi Meton and EPN)
４	Lead and its compounds
５	Hexavalent chromium compounds
６	Arsenic and its compounds
７	Mercury, alkyl mercury and other mercury compounds
８	Polychlorinated biphenyl (PCB)
９	Trichloroethylene
10	Tetrachloroethylene
11	Dichloromethane
12	Carbon tetrachloride
13	1,2-dichloroetan
14	1,1-dichloroethylene
15	1,2-dichloroethylene
16	1,1,1-trichloroethane
17	1,1,2-trichloroethane
18	1,3-dichloropropen
19	Tiuram
20	Zemadine
21	Thiobencarb
22	Benzene
23	Selenium and its compounds
24	Boron and its compounds
25	Fluorine and its compounds
26	Ammonia, ammonium compounds, nitrite compounds and nitrate compounds
27	Vinyl chloride monomer (chloroethylene)
28	1,4-dioxane

Standards for Structure, Equipment, and Method of Use of Hazardous Substances and Designated Facilities for Storage of Hazardous Substances (Article 12-4 of the Act)

Structure and Equipment Scope
Structures and equipment to which the standards are applied

Floors and surroundings (Article 8.3 of the Regulations)

The floor and surroundings of the installation locations of specific facilities for using harmful substances and designated for storage of harmful substances must be materials and structures that can prevent water containing harmful substances from penetrating into the basement and outflow outside the facility.

Piping, etc. (Article 8-4 of the Regulations)

When installing pipes (*) attached to the main body of harmful substances and designated facilities for storing harmful substances on the ground are installed on the ground, use a material and structure that can prevent leakage of water containing harmful substances, or if there is leakage. Must have a structure that can confirm leakage.
In addition, when installing underground, use a material and structure that can prevent leakage of water containing harmful substances and penetration into the basement, or a structure that can confirm leakage etc. if there is leakage or penetration into the underground. Must have.
※Piping body, fittings, flanges, valves, pump equipment, etc. where water containing harmful substances flows through water containing harmful substances

Drainage ditches, etc. (Article 8-5 of the Regulations)

Drainage trenches (*) of the drainage system attached to the main body of the harmful substance use specific facilities and designated for storage of harmful substances must be materials and structures that can prevent water containing harmful substances from penetrating into underground.
※Drainage drains, drainage pumps, etc. that connect to the facility itself and flows water containing harmful substances flows

Underground storage facilities (Article 8-6 of the Regulations)

Of the underground storage facility itself and the accompanying piping, etc., the underground storage facility itself must be a material and structure that can prevent water containing harmful substances and penetration into the underground.

Method of use (Regulation, Article 8-7)

Accepting, transferring, distributing water containing harmful substances pertaining to specific facilities for using harmful substances and designated facilities for storage of harmful substances shall be carried out in a way that water containing harmful substances does not scatter, run out, or penetrate underground. Operation of the facility must be performed properly, such as checking the replenishment of water containing substances and the operating status of equipment.
In addition, if water containing harmful substances is leaked, measures must be taken to prevent leakage immediately, collect and reuse water containing the leaked harmful substances, or treated appropriately so as not to interfere with the living environment of conservation.
Businesses need to create a management procedure that describes how to use, inspection methods, number of inspections, etc.
Guide to Formulate Management Guidelines (Ministry of the Environment website) (outside site)
Example of preparation of management guidelines (Ministry of the Environment website) (outside site)

Criteria for judging water that does not contain harmful substances

If the concentration of harmful substances in wastewater from the cleaning facility can be less than the concentration shown in the following table by washing the equipment with harmful substances attached several times and collecting waste liquid in a separate container, etc., the rinsing water can be judged as water that does not contain harmful substances. In that case, structural standards and periodic inspections are not applied to pipes, drains, etc., because water containing harmful substances does not flow.
However, structural standards and periodic inspections are applied regardless of the concentration of harmful substances on the floor and around the cleaning facility itself.

Table Concentrations where hazardous substances are deemed not to be detected
Type of Hazardous Substances	Concentration	Type of Hazardous Substances	Concentration
Cadmium and its compounds	Less than 0.001 mg/L	1,2-dichloroethylene	Less than 0.004 mg/L (For ciss and transformer bodies)
Cyanide compounds	Less than 0.1 mg/L	1,1,1-trichloroethane	Less than 0.0005 mg/L
Organic phosphorus compounds (limited to parathion, methylparation, methyldi Meton and EPN)	Less than 0.1 mg/L	1,1,2-trichloroethane	Less than 0.0006mg/L
Lead and its compounds	Less than 0.005 mg/L	1,3-dichloropropen	Less than 0.0002 mg/L
Hexavalent chromium compounds	Less than 0.01 mg/L	Tiuram	Less than 0.0006mg/L
Arsenic and its compounds	Less than 0.005 mg/L	Zemadine	Less than 0.0003 mg/L
Mercury, alkyl mercury and other mercury compounds	Less than 0.0005 mg/L	Thiobencarb	Less than 0.002 mg/L
Alkyl hydrocarbon compound	Less than 0.0005 mg/L	Benzene	Less than 0.001 mg/L
Polychlorinated biphenyl (PCB)	Less than 0.0005 mg/L	Selenium and its compounds	Less than 0.002 mg/L
Trichloroethylene	Less than 0.002 mg/L	Boron and its compounds	Less than 0.2 mg/L
Tetrachloroethylene	Less than 0.0005 mg/L	Fluorine and its compounds	Less than 0.2 mg/L
Dichloromethane	Less than 0.002 mg/L	Ammonia, ammonium compounds, nitrite compounds and nitrate compounds	Ammonia nitrogen: Less than 0.7 mg/L, nitrite nitrogen: Less than 0.2 mg/L, nitrate nitrogen: Less than 0.2 mg/L
Carbon tetrachloride	Less than 0.0002 mg/L
1,2-dichloroetan	Less than 0.0004 mg/L	Vinyl chloride monomer (chloroethylene)	Less than 0.0002 mg/L
1,1-dichloroethylene	Less than 0.002 mg/L	1,4-dioxane	Less than 0.005 mg/L

Examination method specified by the Minister of the Environment based on the provisions of Article 6-2 of the Enforcement Regulations of the Water Pollution Control Law (Ministry of the Environment website) (outside site)

Periodical inspections (Article 9-2-2-2 of the Regulations)

Periodic inspections of facilities that use harmful substances and designated facilities for storage of harmful substances shall be conducted by visual inspection, etc. (excluding cases where visual methods are difficult to visualize, etc., and facilities are used). Underground storage facilities, such as the facility itself, the accompanying pipes and drains, must be performed in accordance with the structural standards.
If an inspection confirms abnormality pertaining to specific facilities that use harmful substances, leakage of water containing harmful substances, or penetration into the basement, necessary measures such as repairs must be taken immediately.

Record and preservation of the results of periodic inspections (Article 9-2-3 of the Regulations)

When a periodic inspection is performed, the following items (1) to (5) must be recorded and stored for 3 years.
Example of preparation of periodic inspection table (Ministry of the Environment website) (outside site)
①Hazardous substance use specific facilities and designated hazardous substance storage facilities
②Inspection date
③Inspection methods and results
④The name of the person who conducted the inspection and the person in charge of the inspection
⑤When repairs or other necessary measures have been taken based on the results of the inspection, the contents of the inspection.
In addition, if abnormalities or leaks of water containing harmful substances, or penetration into the underground are confirmed to be related to specific facilities that use harmful substances or designated storage facilities for storage of harmful substances, or penetration into the underground, the following items (1) to (5). Please try to store for 3 years.
①Hazardous substance use specific facilities and designated hazardous substance storage facilities for which abnormalities have been confirmed
②Date on which abnormalities were confirmed
③Details of abnormality, etc.
④Name of the person who confirmed abnormality, etc.
⑤When repairs or other necessary measures have been taken, the details of such measures.