Didipio Mine implements an ISO-certified environmental management system (ISO14001:2015) and occupational health and safety management system (OHSAS 18001:2007).
Didipio secured ISO certification prior to the 2015 issuance of a national administrative order, requiring all operating large-scale metallic mines to obtain an ISO 14001 certification for environmental management systems. We are currently in the process of securing ISO 50001 Energy Management System and are implementing processes and initiatives to reduce energy consumption and be more efficient in compliance with this standard.
In addition to reforestation and greening programs, Didipio’s biodiversity initiatives include:
- Fund the Kasibu Municipaility initiative to appoint forest rangers (Bantay Gubat) who manage and protect public forest.
- Support annual ecological assessment and biodiversity monitoring by two local state universities (Nueva Vizcaya State University and Quirino State University), under our Environmental Compliance Certificate.
- Collaborate with PHD students from Nueva Vizcaya State University to conduct a study on the natural and social dimensions of stream-riparian ecosystems in Didipio.
- Assess upstream, midstream and downstream river and watershed rehabilitation areas.
- Partner with the Isabela State University to support the Addalam River Integrated Watershed Management Study.
- Partner with the International River Foundation to support the restoration of the Cagayan River.
- Utilize mass propagation of endemic plants thru macrosomatic clonal propagation (using one tree to harvest more than one seedling).
- Established a dedicated nursery to grow a range of forest tree species.
Didipio has established plantation sites for our Mining Forest Program and actively participates in the Philippines Government’s National Greening Program.
Since the 1997 commencement of the Mining Forest Program, Didipio has planted a total of 2,075,411 trees. As of the third quarter 2018, we had reforested a total area of 1,258.30 hectares.
All reforestation includes a percentage of trees that do not survive relocation. Our reforestation survival rate is 92%, above the Philippine national standard of 80%.
Didipio works with host communities, government and other stakeholders to address concerns around the mine’s impact on water, local challenges with water access and use, and how we can contribute to better watershed management.
The Didipio community has a population of approximately 4,000 individuals in an estimated 900 households. As outlined in the 2017 Mine Rehabilitation Fund Committee report, Water Resource Study for Barangay Didipio, natural spring water is the main source of the community’s drinking water.
The Didipio Mine is working with the community for the construction of the Didipio Water System Project, due for completion in 2019. This project includes water storage, treatment and supply infrastructure that will enable community members to access reliable and safe potable water in each household. The Php37m (US$698,000) system will have the capacity to provide water for up to 11,000 individuals in the community (or around 2,400 households).
The nature of the mined ore at Didipio allows for extraction using grinding and flotation processes with water, and we do not use cyanide or mercury for gold and copper recovery. During grinding and floatation, the mined ore is ground to very fine particles to separate the gold and copper from the waste material or mine tailings. The mine tailings generated from the processing plant is stored at the tailings storage facility (TSF). The water from the TSF is further treated in the water treatment plant, an automated facility. Using a flocculation and coagulation process, the water storage plant significantly reduces total suspended solids (TSS) to 70 parts per million, well below the government standard for Class D water at 150ppm.
We built a paste-backfill plant where approximately 30-40% of the mine tailings are mixed with cement and used as backfill material for the underground voids, which reduces the volume of tailings delivered to the TSF.
We undertake a quarterly Toxicity Characteristic Leaching Procedure at the TSF to measure solids and naturally-occurring heavy metals in the water. Samples are tested by a government-accredited laboratory.
Didipio’s TSF is constructed to standards that exceed Philippine Guidelines and meet International Commission on Large Dams (ICOLD) guidelines and the Category High C Australia National Committee on Large Dams (ANCOLD) guidelines. The Mines and Geosciences Bureau conducts a quarterly audit of the TSF and GHD engineers supervise all construction. Engineering Geology Ltd, an independent third-party, conducts an annual review of TSF construction to ensure it continues to meet the ICOLD, ANCOLD design criteria.
Didipio minimizes the use of freshwater resources by recycling process water. Data from 2014 to mid-2018 shows we have recycled an average of 87% of process water. Since we commenced commercial production, we have consistently increased the amount of water that recycled in the process plant. This year, Didipio successfully commissioned the Didipio Water Recycling and Purification Plant, which treats sewage water and maximizes recycling of water resources at the mine site.
Didipio operations conduct daily, weekly, monthly and quarterly water quality monitoring in line with all the requirements of the Department of Environment and Natural resources (DENR).
Hazardous Waste Management
Like many industrial operations, the Didipio mine generates waste, such as used oil, rags, and fluorescent lamps, which are defined as hazardous and require strict management. All hazardous waste is reported to the Environmental Management Bureau (EMB) and those reports contain information on the types of wastes, treatment procedures for all wastes generated and a Certificate of Treatment issued by a government-accredited treater. The EMB checks performance against their requirements and issues compliance certificates quarterly.
Prior to the development of the Didipio operation, artisanal mining was prevalent in the area and some small-scale mining upstream from of Didipio continues today.
The Baseline Study of the Major River System and Tributaries of Barangay Didipio conducted by the Nueva Vizcaya State University in 2004, showed elevated total suspended solids (TSS) levels in the Didipio river.
From 2014 to 2018, using water management technologies and in collaboration with government and artisanal miners, we have seen an improvement of the natural river (classified as Class D prior to the development of the operation).
The water management technologies Didipio has deployed include the water treatment plant, sewerage treatment plant, the Didipio Water Recycling and Purification Plant using hyper-ozonation technology and siltation (suspended solid settling) ponds.