Tailings are not produced at Kounrad due to the nature of the leaching operation, but mineral waste materials are generated by mining operations at Sasa.
Sasa tailings storage facilities
There are five facilities at site, all owned and managed by Sasa.
|Location (Gauss Kruger coordinate system)||Y=7,626,188; X=4,664,211||Y=7,626,384; X=4,663,656||Y=7,626,777; X=4,663,584||Y=7,627,228; X=4,663,165||Y=7,627,601; X=4,662,437|
|Status||Closed||Closed||Closed||In closure phase||Active|
|In operation||1964-1974||1974-1990||1990-2003, 2006-2007||2007-2020||2020 onwards|
|Height (m)||44||62||61||63||22 (final 61)|
|Current tailings storage volume (Mm3)||1.4||4.8||4.9||5.0||0.2|
|Planned 5 year tailings storage volume (Mm3)||As above||As above||As above||5.2||2.1|
SEPTEMBER 2020 TSF4 LEAKAGE
On 14 September 2020, there was a short-term leakage of approximately 8,000m3 of tailings into the local river. The leakage occurred due to water ingress along the composite liner interface through to the dam, resulting in a loss of strength and the subsequent subsidence of the dam crest. The leakage stopped soon after and nobody was harmed.
CAML retained the services of global consultants, Knight Piésold Limited, to advise on tailings management, and Wardell Armstrong, to advise on environmental matters.
Company announcements regarding TSF4 are below:
All Sasa facilities are of downstream construction.
Downstream facilities begin with a ‘starter wall’. Tailings are discharged into the dam and cycloned such that the fine component (slimes) flows into the ponded section and the coarse fraction (sands) flows in the opposite direction to create the ongoing raise in the dam wall.
Downstream design tailings storage facilities are typically suitable for areas with seismic activity and high rainfall. In addition, all tailings dams must be designed to take into account the specific environmental setting in which they are to be located, which will include grain size, slope angle and height of dam wall above the pond.
As part of CAML’s management strategy for the tailings dams at Sasa, the following processes are in place:
- A dedicated team from the Flotation Department is responsible for the day-to-day management and monitoring of the facility
- The dam is monitored 24 hours per day by the team, which is led by a highly experienced engineer (‘Responsible Tailings Facility Engineer’)
- An external Independent Tailings Engineer (‘Engineer of Record’) is responsible for monitoring, reviewing and reporting on Sasa’s TSFs on a monthly basis
- The Engineer of Record presents the report findings to Sasa’s management and TSF Stability Committee, which is chaired by the Sustainability Director
- The Committee reviews the following monitoring data from the Independent Tailings Engineer:
- water levels in the piezometers in the dam wall
- TSF drainage flow rates and water quality
- survey levels
- grain size analysis from the cyclones
- height of the dam wall relative to pond levels etc
- dam slope angle relative to design
Review and monitoring of Sasa tailings storage facilities
Sasa’s tailings dams have been constructed in line with North Macedonian standards. The monitoring data generated from analysis of the tailings facilities is regularly reviewed by Stip University, which produces monthly reports for the mine.
In 2016, Golder Associates (global tailings dam experts) undertook an audit and review of the facilities at Sasa and, in February 2019, CAML instructed that group to perform a third-party stability review of TSF3.2.
In September 2020, global consultancy, Knight Piésold, was retained to undertake a full independent review of TSF4 following the leakage.
SRK Consulting has developed closure plans for Sasa, which include closure of the tailings storage facilities. Long term monitoring procedures of the older facilities are already in place, and future mine closure plans and requirements include regular tailings dam monitoring. Formal analysis of the downstream impact on communities, ecosystems and infrastructure has also been undertaken by the Faculty of Civil Engineering in Skopje, North Macedonia and by SRK Consulting.
Church of England Pensions Board Investor Mining and Tailings Safety Initiative
Chief Executive Officer