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:
① Underground seepage of water
② Drainage using groundwater level lowering methods
③ Generation of polluted water due to washing of various machinery and vehicles
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 The Water Pollution Control Act (see Articles 3 and 12)
sets standards for the discharge of water into public water bodies from factories and businesses with specific facilities.
② The Sewerage Act (see Article 12 and Articles 8-9 of its Enforcement Order)
regulates the discharge of polluted water into sewers.
③ The River Act (see Article 16 of its Enforcement Order)
sets out procedures for discharging polluted water (50 m3/day or more) into rivers.
④ The Fisheries Resources Protection Act (see Article 18)
regulates construction work in areas designated by the Act for the purpose of protecting fisheries resources.
⑤ The Natural Parks Act and the Natural Environment Conservation Act (see Articles 13 and 25)
regulate wastewater discharge within the areas of national parks, quasi-national parks, etc.
⑥ Local Ordinances
Many prefectures and designated cities have enacted pollution prevention ordinances, sewerage ordinances, waste disposal ordinances, fishing rights ordinances, etc., and construction wastewater may be regulated.
⑦ Provisional Guidelines for Construction Work Using Chemical Injection Methods: These guidelines
stipulate the selection, design, construction, and water quality monitoring of construction methods necessary to prevent health damage to people and pollution of groundwater, etc., using chemical injection 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 System, volume, water quality, and water use status of the rivers, etc. from which the water will be discharged.
② Regulations and necessary procedures and notifications under laws and ordinances such as wastewater discharge standards.
③ Water quality and volume of polluted water or wastewater generated as a result of the construction.
④ Sludge treatment method
. ⑤ Site for the installation of the wastewater treatment facility.
①
Use a coagulant to settle suspended solids in a sedimentation tank, sedimentation basin, or coagulation tank.
②
Solidify the sludge by sun drying or mechanical dewatering.
③
Discharge the supernatant water from the sedimentation tank or sedimentation layer.
④
Adjust the pH of alkaline or acidic water before discharging.
⑤
Remove oil from the discharged water by flotation or adsorption.
(Reference: "Standard Specifications for Tunneling - Shield Tunneling Method, Established 2006," Japan Society of Civil Engineers)
Environmental assessment
(environmental impact assessment)
Overview of the Japan-Korea Tunnel
