skip to

This Page is HomeSustainabilityEnvironmental InitiativesEnvironment Preservation Initiatives

Environment Preservation Initiatives

Environmental Activity

As part of our environmental preservation efforts, we are promoting activities to prevent global warming, to reduce environmental impact in our offices and to properly manage chemical substances.

Initiatives to Prevent Global Warming

Reducing CO2 Emissions

We have set a target of "reducing Scope 1 and Scope 2 emissions by 50% and Scope 3 emissions by 30% compared to FY 3/20 by FY 3/2031, and achieving carbon neutrality for Scope 1 and Scope 2 emissions by FY 3/2051.
Our CO2 emission reduction targets are consistent with scientific findings, and we are currently applying for SBT (Science Based Targets)*1 certification.

Please click here to view reduction targets in detail

Please click here to view CO2 emissions results

Promotion of Energy and Resource Saving in Offices

Reduction in Consumption of Copier Paper

We work on copier-paper reduction activities through the use of double-sided copying, one-sheet copying, use of backs of printed papers, use of electronic media, use of recycled paper, and management of the amount of copier paper purchased. In FY 3/23, the amount of copier paper used per person was 4,785 sheets (6.4% reduction from the previous year),showing a company-wide downward trend. The use of iPads and other electronic devices and working from home have contributed to the reduction, and we will promote the same initiatives going forward.

Copier paper consumption per person

Green Purchases

As part of our green activities in the office, we monitor the ratio of green product purchases for office supplies. To the overall green purchase ratio for FY 3/23 was 56.7%. We will actively work to purchase green items whenever available. Also, in items which saw improvement in green purchase rates, which are paper, electrical appliances and lighting apparatus, we will continue to promote the purchase of green products.

Copier paper consumption per person

Reduction of Electricity Use

In order to tackle global warming issues, we continuously promote COOL BIZ and WARM BIZ initiatives (dressing in more relaxed outfits in mid-summer and mid-winter to cope with extreme temperatures) and put up the educational poster at the office entrance. In FY 3/23, the per-capita electricity consumption was 1,864kWh (down 0.8% from the previous year), thanks to employees' awareness of energy saving efforts and technical progress in energy conservation. We will continue to implement power-saving measures such as turning off lights during lunch break, turning off partial lights when leaving the office, setting air conditioner in mild temperatures and operating air conditioners in limited areas after hours, as well as using electric fans instead of air conditioners.

Electricity consumption per person

Separate Collection of Waste

To make waste separation easier, we place separate boxes for waste collection on each office floor. Separate waste collection rate remains high at 99.9%. We also collect plastic bottle caps and bottle can caps.

General Waste Separation Status

Treatment of Hazardous or Chemical Substances

In recent years, various environmental issues have been identified due to increasing hazardous substances. These include soil contamination issues caused by heavy metals and chemical substances, and environmental pollutant such as dioxins produced at incineration facilities. We are actively working to implement countermeasures and develop technologies to tackle these issues.

Soil Contamination

Since the enactment of Soil Contamination Countermeasures Act in 2003, through two revisions in 2010 and 2017, the government expanded investigative initiatives, tightened regulations, and introduced new systems to manage contamination in waterfront areas and natural and reclaimed land. In light of the tightening regulations, we established a team that specializes in surveys and countermeasure implementations, and we are working on further development green technologies while ensuring compliance with related laws and regulations.

Dioxin, etc.

We started focusing on the toxicity of dioxins early on and have been working on the development of dioxin remediation technologies. In 2000, we became the first company in Japan to dismantle an incineration facility with dioxin exposure prevention measures, and since then, we have dismantled approximately 80 incineration facilities. Since then, we have dismantled about 80 incineration facilities and properly managed and disposed of the waste and contaminated soil generated in the course of the dismantling.

  • In-situ improvement of VOC-contaminated soilIn-situ improvement of VOC-contaminated soil
  • Status of measures for dioxin-contaminated soilStatus of measures for dioxin-contaminated soil

Recycling of Construction Generated Bi-products

Effective re-utilization of construction generated soil is an important issue for the construction industry. We have established a wide-area network of shipping bases across the nation and are promoting the effective utilization of soil and sand. We are also working with the steel industry to develop new environmentally friendly dredging technology to explore the new use of dredged soil.

Construction Generated Soil and Soil Contamination

In 2014, we expanded our Ichikawa office in Chiba Prefecture, which had been engaged in marine transportation of construction soil and utilization of reclamation material, and opened the Ichikawa Soil Reuse Center as a facility to receive construction generated soil and contaminated soil. The center makes effective use of the received contaminated soil by converting it into raw materials for cement and other purposes.
We opened a new Soil Reuse Center in Yokohama in 2017 and another one in Nagoya in 2018. In 2021, the center in Nagoya started reception of contaminated solid. In 2022, we began production and sales of fluidized treated soil (construction sludge recycling business) in Ichikawa, and we are promoting comprehensive wide-area utilization and appropriate treatment of soil generated in the Kanto and Chukyo regions.

  • Ichikawa Soil Recycling Center
    (Contaminated soil treatment
    business permit:
  • Yokohama Soil Recycling Center
    (Contaminated soil treatment
    business permit:
  • Nagoya Soil Recycling Center
    (Contaminated soil treatment
    business permit: No.10900010002
    Industrial waste disposal division
    of labor: Permission

Effective Utilization of Soft Soil and Dredged Soil

Dredging works to maintain harbor berths and deepening ships channels in port may generate a large amount of dredged soil. Utilization of the generated soil and sand is an imminent environmental issue for us as a company engaged in dredging. We are developing various technologies to tackle these issues.

Calcia Soil Improvement Technology

Calcia reforming technology improves the physical and chemical properties of dredged soil by mixing the soft dredged soil generated from the port works with the Calcia reforming material (materials for controlling the composition and adjusting the particle size of steelmaking slag from converter system) generated in the steelmaking process.
The Calcia reformed soil made by the Calcia reforming technology can be widely applied in marine constructions such as landfill material, partition embankment material, revetment backfill material, and marine embankment material for repairing route burial. It is expected to shorten the construction period and reduce costs.
Our company has developed a high-performance Calcia reforming technology using short fibers and mud improvement materials and is working on dredged soil recycling at ports.

  • Overview of the Calcia Reforming Technology

Calcia Dropping Barge

Calcia Improved Soil Drop Mixing Vessel 'Ocean3'

As attention towards a recycling-oriented society increases, there are various plans underway to apply the Calcia reforming technology to utilize dredged soil in reclamation work and other such projects.
To meet those needs, our company has remodeled an existing reclaimer vessel* and equipped them with a system for feeding Calcia reforming material. This is our "Calcia Drop-Mixer" which enable us to obtain the prescribed mixing quality for the resultant material on board.
*Reclaimer vessel: A work vessel used in coastal reclamation etc. This vessel unloads soil and sand (via a backhoe or similar equipment) transported by a soil carrying vessel, and discharges it to landfill sites via a conveyor or the like.
*This vessel is co-owned with Kanmon Kowan Construction Co., Ltd.


  • Supports large-scale construction (2,500 to 4,000m3)
  • Mixing is completed when dropped from the Calcia Drop-Mixer vessel
  • Enables real time quality control (mixing ratio, density, etc.)

Calcia Improved Soil Drop Mixing Vessel 'Ocean3'

Principles of Drop-Mixing
Dredged soil and Calcia reforming material are mixed when down dropped from a conveyor belt or a spreader and collided with an iron plate or a slope or the like.

Clayguard Method

⋅Clayguard Method
The Clayguard method intercepts water on the sides and bottom of a marine waste disposal site by using soil seepage material. The seepage material is made from construction soil such as dredged clay, mixed with bentonite and other sub-materials to improve water-tightness. Since no solidifying material is used, the material presents self-compacting and deformation-following properties, and can follow external forces such as ground subsidence and waves to maintain its water-tightness for a long period of time.

Sludge Recycling Business

This business manufactures a water-absorbing mud stabilization material "Watoru" made from paper sludge incineration ash discharged from papermaking companies, and supplies it for construction.
The water-absorbing mud stabilization material "Watoru" is a hydration-treated product made by mixing a special chemical with incinerated ash from paper manufacturing sludge generated by papermaking companies. In addition to physical reforming through water-absorbing (with an instantaneous reforming effect), it also has chemical reforming ability over time (with gradual strength development).
It is highly effective not only for processing dredged soil in harbors, rivers, and lakes, but also for processing mud and sludge generated by excavation on land.

Watoru After treatment with Watoru
  • *This business is conducted by JAIWAT Co., Ltd. (our wholly owned consolidated subsidiary)

Food Recycling Business

This business processes and sells compost materials made from organic waste discharged from food-related companies, etc.

<Characteristics of the business>

  • With the automatic agitator (scoop-type) and the forced air circulation (aeration), collected food waste is subject to primary fermentation for about 1 month, and then further fermentation and maturation for about 3 months to produce complete compost.
  • Since the Miki Composting Center is located near the Hanshin district with concentration of many food-related companies and easily accessible from interchanges of the expressway, it can contribute to the reduction of waste transport costs.

Use of recycled product (compost "Minami-No-Hikari")

  • Because it is made from food waste, it is a safe and nature-friendly organic compost.
  • Fully matured after four months of fermentation and aging, there is no unpleasant odor.
  • Fully meets the quality standards of the NPO Japan Bark Compost

Association, surpassing common composts. It can be used in various situations from full-scale agriculture to landscaping/greening projects and kitchen gardens.
The performance of our recycled products has been highly evaluated, and our product delivery record is improving.

Inside the facility, Panoramic view of the facility, Product 'Minami-No-Hikari'

  • *This business is conducted by Miki Biotech Co., Ltd. (our wholly owned consolidated subsidiary)

Offshore Wind Power Generation

Construction of Offshore Installation Vessels Equipped with a Large Crane


⋅CP-8001 -operating Japanese coastal waters

In December 2018, Penta-Ocean Construction completed the construction of CP-8001, the first Japanese multi-purpose SEP equipped with a large crane. The vessel is able to achieve high utilization rate, high accuracy, and safe crane operation even under harsh marine and weather conditions. After undergoing various sea trials in Japanese coastal waters and used in a marine project, the vessel was utilized for the removal of a bottom-fixed offshore experimental wind power facility and a wind observation tower off the coast of Kitakyushu in October 2019. It is now playing an active role in various areas across Japan, such as surveys of the seafloor.


  • Designed to perform installation of large-scale marine structures, such as 10 MW wind turbines
  • Operational in deep waters (up to 50 meters)
  • Equipped with a latest continuous hydraulic jacking system developed by GustoMSC
  • Designed to automatically control the hull position via Dynamic Positioning System (DPS)
  • Carries adequate accommodation space and a helicopter deck for emergency human transport


⋅1,600t lifting capacity offshore installation vessel with a large crane to accommodate larger wind turbines
Our company is currently constructing a second multi-purpose SEP equipped with a large crane to respond to the trend toward larger offshore wind turbines and their foundations. The construction of this vessel has been outsourced to Singapore-based PaxOcean Engineering. It is slated for completion and delivery in September 2022. The SEP will be owned by PKY Marine (in which our company has a 65% stake), jointly established by Penta-Ocean Construction, Kajima Corporation, and Yorigami Maritime Construction in February 2020.


  • Equipped with a fully revolving crane with a 1,600t lifting capacity
  • Designed to install 10-12MW turbines and various foundations, including monopiles, jackets, etc.
  • Can carry multiple 10-12MW class wind turbines for efficient installation works
  • Operational in deep waters (up to 50 meters)
  • Able to maintain the hull position by Dynamic Positioning System (DPS)