With this article we wish to summarise the main facts regarding the environmental incident at the UPM Paso de los Toros pulp mill in Uruguay in August 2023, ensure that this information is readily available, and share our learnings from the case.
Despite UPM’s high standards of process control, sodium hydroxide, a chemical commonly used in pulp production mixed with rainwater, leaked from a stormwater basin through the soil into a nearby creek, causing the pH level of the water in the creek to temporarily increase. The reason for the leak to the stormwater basin was a technical failure and the fact that this basin was not originally constructed to store water which contains a significant concentration of chemicals. The leak caused mortality in the aquatic biota in a section of the creek during the leak.
The creek flows first into a lagoon and then into the Río Negro river, where the effect of the leak was very limited in quantity and duration.
The UPM team in Uruguay immediately took all of the necessary corrective measures and notified the environmental authorities and the local community about the incident, and also issued two press releases on the incident on 17 Augustand 18 August.
In October 2023, Uruguay’s Ministry of Environment imposed a sanction of approx. USD 188,000 on UPM for non-compliance with the environmental management plan for the pulp mill.
Learnings and follow-up
We have investigated the causes of the incident with the Uruguayan environmental
Authority DINACEA and have implemented all the necessary corrective measures based on our learnings and in accordance with the authority’s instructions.
The repairs to the stormwater basin from which the water containing sodium hydroxide leaked have been completed. Operational and maintenance procedures in the chemical storage area have been reviewed and updated, and the findings have been used to review and improve other concrete structures on the mill site.
Regarding the impacted area, all the measures requested by the authorities were taken, and the corresponding monitoring continues to follow-up the ongoing natural recovery of the area.
The creek has shown sustained natural recovery since the incident in August 2023. Monitoring is conducted by independent environmental experts every 15 days to track the progress of the recovery, and the sampling campaigns are informed to the stakeholders in the mill follow-up commission so that they have the opportunity to join the experts. This monitoring measures various water and sediment parameters, diversity and abundance of aquatic biota, among other aspects.
UPM regularly presents the environmental monitoring results in the mill follow-up commission, which includes the environmental authorities and other stakeholder, and all these presentations are publicly available on the website of Uruguay’s Ministry of Environment at https://www.ambiente.gub.uy/oan/proyectos/planta-de-celulosa/ > Comisión de Seguimiento. The latest presentation from 2 May 2024 covers the environmental performance of the UPM Paso de los Toros pulp mill after its first year of operations.
