Update on action taken following the dikes break at SOMAIR mine in Niger

During the night of December 13 to 14, 2010, three dikes at the effluent storages ponds at the SOMAÏR mine in Niger broke one after the other, spilling about 50,000 cu. meters of effluent into the surrounding area.

The affected area, which extends over about 20 hectares, is located within the confines of the SOMAÏR site and thus several kilometers from the town of Arlit.

As soon as the incident was noticed, SOMAÏR personnel immediately took the necessary steps to seal the dikes, pump up the spilled effluent, strip the affected ground and carry out the initial environmental analyses.

Local authorities, including the mayor and prefect, as well as representatives of civil society were immediately informed of the situation.

Following the incident, virtually all of the effluent was recovered and transferred to the adjacent ponds, and the ground was stripped to a depth of 50 cm as a preventive measure. These operations were completed on January 26, 2011.

Initial investigations indicated that there was no contamination of drinking water and no public health risk. Environmental analyses conducted regularly since the incident have confirmed these conclusions.

In accordance with its commitment to transparency, AREVA is making these results available to the public on its website.

Drawing on the lessons learned from this incident, action plans have been developed and put in place to prevent a failure of this kind from occurring again. Emergency procedures to be taken in the event of a critical incident have also been strengthened.

Basic information
- What is an effluent?
  - An effluent is residual liquid from an industrial process.
  - In this case, the effluents come from the processing of the uranium ore extracted from the SOMAIR open-pit mines.
- What type of effluents flowed out of the damaged ponds?
  - These effluents were a mixture of industrial water and substances in suspension from the ore-processing operations.
  - The effluents in the ponds come from the spin-drying of process residues and the washing of ore filtering tanks. They contain uranium and other metals naturally present in the ore.
- What is the radioactivity level of these effluents?
  - These are uranium-bearing solutions with a low level of radioactivity.
- Which is the storage capacity of the effluent ponds?
  - The unit storage capacity of the ponds ranges from 63,000 to 75,000 m³. There are ten evaporation ponds at the SOMAIR site.
- What is the average monthly volume of effluent produced at Somair?
  - On average, around 75,000 m³of effluents are produced at SOMAIR each month.
Incident
- What caused this incident?
  The analysis of the incident indicates that the cause was overfilling Pond No. 1 during the cleaning of a tank at the processing plant.
  This overfilling is thought to have caused the effluent to overflow, gully and eventually rupture the dike of Pond No. 1. It then flowed into Pond No. 2 and then Pond No. 6, rupturing dikes in each case. When the dike of Pond No. 6 broke, the effluent spread over an area of about 20 hectares.
- Has the leak been plugged?
  The leak was plugged in the hours immediately after the incident was noticed.
  The SOMAIR teams used mining equipment to rapidly stop the effluent from escaping from the damaged ponds (Nos.1, 2 and 6) by reinforcing the dike of Pond No. 6. They began pumping operations and transferring effluent that had flowed out into the adjacent ponds.
  The other ponds (Nos. 3, 4, 5, and 7 to 10) were not damaged.
- What actions were taken following the incident?
  The local authorities (Mining Bureau, mayor, Prefect) were informed as soon as the incident was discovered.
  Substantial human and material resources were mobilized to plug the break, pump up the effluent, strip the soil in the spill area, and carry out the first environmental analyses.
  The pumping systems deployed in the area enabled the recovery of a large share of the spilled effluent. At the same time, the ground in the spill area was stripped up to a depth of 50 cm as a precaution, and the 150,000 tons of earth that was removed has been stored in the Low Activity Waste (LAW) storage area on site.
  A briefing was held for civil society representatives in the days following the incident.
- What steps have been taken to prevent another accident of this kind?
  A specialized firm has also been asked to carry out a geotechnical audit to determine the structural improvements to be made to the ponds.
  For the time being, the dikes of the ponds have been reinforced, and they will soon be raised to make the structures more solid.
  Surveillance procedures for the dikes and effluent storage ponds were revised to prevent another incident, and the new procedures take into account the consequences of what has occurred.
  The risk prevention plan for this type of storage has also been reviewed.
  A reinforced surveillance of the installations is permanently led.
  Since March, 2011, a permanent pumping system is in operation, to prevent water accumulation at the bottom of the slag heap (accumulation of mine tailings).
Environment and health
- Does the incident represent a health risk for the populations close to the Somair mine?
  There is no danger for the population. The incident took place on the SOMAIR plant and mining site, which is several kilometers from the town of Arlit.
  Analyses reveal no pollution of groundwater (no change in pH or in nitrate or sulfate content).
  A portion of the effluents were pumped up. The effluents also have a limited ability to infiltrate the soil because of their composition and the type of soil in the flooded area.
  Analyses of water samples were done after the incident and will continue for several months. Additional boreholes to check the level and quality of groundwater with piezometers were also dug to allow more precise monitoring of the aquifers.
- Is the ground over which the effluent spread permanently polluted?
  The area concerned is approximately 20 hectares.
  The ground over which the effluent spread has been stripped to a depth of up to 50 cm. The 150,000 tons of soil that were removed are now stored in the Low Activity Waste (LAW) storage area on the mine site.
  The results of the stripping were checked with a gamma radiation counter, and the stripping was shown to have been effective.
Controversies
- Is this the first major incident of its kind at a mining site in Niger?
  No, this kind of incident occurs occasionally at mining operations. The only one at this site dates back to the early 1980s.
- Why aren’t the studies and measurements on the ground being conducted by or in collaboration with the local NGOs (i.e. Aghir in Man)?
  In line with the Group’s transparency policy, the civil society was informed of the incident. SOMAIR’s management invited civil society representatives to come to the site and described the situation to them frankly and openly. They will be kept informed of the progress in the work.
  AREVA and SOMAIR’s teams are qualified to conduct these studies. They are being carried out in a fully transparent manner, and the results will be made public.
  In addition, the supervisory authorities (Centre National de Radioprotection, Ministry of Mines, Ministry of the Environment) are closely involved with the monitoring process and the repair work being done.