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Resource Circulation


All employees of POC participate in 3R (Reduce, Reuse, Recycle) promotion in a bid to reduce waste in daily activities, and starting from FY 2006, we have been implementing zero-emission initiatives throughout the company.

Recycling of Construction Generated By-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.

Calcia Dropping Barge

s 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.)
  • 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

    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

    The utilization of muddy soil generated from dredging of rivers and lakes and excavation work on land is also an important issue for us, and we are developing various technologies to solve this problem.

    Water-absorbing mud stabilization material "Watoru"

    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.

    *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 contributes 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 evaluated, and our product delivery record is improving.

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

    Zero Emission Promotion Activities

    We define zero emissions as the reduction of the final disposal volume of construction by-products to as close to zero as possible, and have been promoting this initiative company-wide since FY 3/2007. POC's overall recycle rate of construction waste for FY 3/23 was 96.0% (98.5% for the previous year), and the final disposal rate was 4.0% (1.5%). The basic unit of final disposal of waste per construction volume was 6,537kg/100 million yen (FY 3/22 result: 2,427kg/100 million yen). In FY 3/23, we will strive to improve the recycling rate and make systematic efforts to achieve zero final disposal of waste.

    Basic Policy for Promoting Zero Emission

    Promote the 3R activities and strive to achieve zero final disposal volume in construction waste

    Priority items

    • Reduction of construction waste generation
    • Ensuring sorted waste collection and waste recycling in line with regional characteristics
    • Conducting educational and awareness-raising activities (sharing awareness)

    Promotion of Energy and Resource Saving in Offices

    As part of our efforts to conserve resources and energy in our offices, we are working to reduce the amount of copier paper used, conduct green procurement, reduce electricity consumption, and sort and collect waste.

    Indicators and Targets

    Amount of Construction Waste

    Total emissions in FY 3/23 increased by 60.6 thousand tons from the previous year to 571 thousand tons. The increase was attributed to a significant rise in the amount of construction sludge from both civil engineering and building construction projects.

    Click to enlarge

    Recycling Rate

    In FY 3/23, the recycling rate for all items decreased by 8.4% to 90.6% for civil engineering projects and increased by 1.6% to 99.6% for building construction projects, resulting in overall rate of 96.0%, down 2.5% from FY 3/22.

    Waste emissions per unit of production increased 11.7/100 million yen to 152.4 tons/100 million yen. Its breakdown showed a different trend for the two business units, with an increase of 31.3t/100 million yen to 163.0t/100 million yen for civil engineering projects, and a decrease of 10.5t/100 million yen to 141.1t/100 million yen for building construction projects.

    The final disposal rate was 4.0% (FY 3/22 result: 1.5%), and the basic unit of final waste disposal per construction volume was 6,537kg/100 million yen (FY 3/22 result: 2,427kg/100 million yen).

    Utilization rate of recycled soil and sand / Effective utilization rate of construction generated soil

    The effective utilization rate of recycled sediment resources in FY 3/23 increased to 71.6% from 55.4% in FY 3/22. The reason for this increase was the rise of effective utilization rate for both civil engineering projects and building construction projects, from 55.2% in FY 3/22 to 67.8% and from 68.0% in FY 3/22 to 96.4%, respectively. In addition, the company-wide effective utilization rate of construction soil generated was 92.6% (FY 3/22 result: 86.8%), an increase from the previous fiscal year.

    Click to enlarge

    Reduction in Consumption of Copier Paper

    We are thoroughly implementing activities to reduce copy paper usage through double-sided copying, one-sheet copying, use of the reverse side, use of electronic media, use of recycled paper, and inventory control of purchased quantities.

    Green Purchases

    As part of our office environmental activities, we manage the ratio of green product purchases for office supplies. We will continue to promote green purchasing.

    Reduction of Electricity Use

    We are working to reduce electricity consumption by implementing power-saving measures such as turning off lights during lunch breaks, turning off partial lights when leaving the office, setting air conditioner temperatures and operating air conditioners in limited areas after hours, and using electric fans.

    Separate Collection of Waste

    Separate trash boxes are placed on each floor of the office for separate collection.