If construction work generates polluted water, appropriate measures must be taken in accordance with relevant laws and regulations to prevent water pollution in public water areas, etc.
The causes of water pollution associated with shield construction include:
①Water seeping out from inside the mine
②Drainage by the groundwater level lowering method
③Generation of polluted water from washing various machines, vehicles, etc.
Contaminated water primarily requires the removal of suspended solids (SS). If cement or chemicals are mixed in, attention must also be paid to adjusting the hydrogen ion concentration (pH) and oil content.
1. Water Pollution Control Act (Articles 3 and 12):
Establishes discharge standards for water discharged into public waters from factories and businesses with specific facilities.
2. Sewerage Act (Article 12, Enforcement Order Articles 8-9):
Regulates the discharge of polluted water into sewers.
3. River Act (Article 16):
Establishes procedures for discharging polluted water (50 m3/day or more) into rivers.
4. Fisheries Resources Protection Act (Article 18):
Regulates construction work in designated areas for the purpose of protecting fishery resources.
5. Natural Parks Act and Nature Conservation Act (Articles 13 and 25):
Regulates wastewater discharge within national parks, quasi-national parks, etc.
6. Ordinances
: Many prefectures and designated cities have enacted pollution prevention ordinances, sewerage ordinances, waste disposal ordinances, fishing rights ordinances, etc., which may regulate construction wastewater.
⑦ Provisional guidelines for construction work using chemical grouting methods
These guidelines stipulate the selection, design, construction and water quality monitoring of construction methods necessary to prevent damage to human health and contamination of groundwater, etc. caused by chemical grouting methods.
Before construction begins, the source of polluted water, its presence and extent, and related laws and regulations, as well as regulatory values, must be investigated, and appropriate purification treatment must be carried out before the water is discharged. In addition, the amount and quality of the discharged water must be measured and reported in accordance with regulations such as ordinances.
① The system of the rivers into which water is discharged, the water volume, water quality, and water usage status, etc.
② Regulations under laws and ordinances such as wastewater standards, and the necessary procedures and notifications, etc.
③ The water quality and volume of polluted water or wastewater generated by construction work, etc.
④ Sludge treatment method
, ⑤ Site for the installation of the purification treatment facility, etc.
1) Suspended matter
is settled using a flocculant in a settling tank, sedimentation tank or coagulation settling tank.
2) Sludge
is solidified by sun drying or mechanical dewatering.
3) The
supernatant water from the sedimentation tank or sedimentation layer is discharged.
4) pH:
Alkaline or acidic water is discharged after adjusting the pH.
5) Oil content
: Oil in the discharged water is removed by floating or adsorption separation.
(Reference: "Tunnel Standard Specifications - Shield Construction Method, Established in 2006", Japan Society of Civil Engineers)
Environmental assessment
(environmental impact assessment)
Overview of the Japan-Korea Tunnel
