Remediation of abandoned mines in Centro Region of Portugal: Urgeiriça uranium mining area example

By project REMIX

Published on 16 July 2018

Portugal

Centro (PT)

About this good practice

Urgeiriça uranium mine was the main mining area due its importance in the processing (chemical treatment facility) of uranium and radium ores, from that and many other Centro region. From 1913 to 1944 mainly produced radium. In 1973, the underground mining ceased and the old tailings became the only source of ore, by ‘in situ’ lixiviation, which ended in 1991. The tailings originated from ore processing were disposed into a small granitic valley with an area of 13 ha (’Barragem Velha’). The total volume of tailings is estimated > 1,4 Mm3.
Empresa de Desenvolvimento Mineiro, S.A. (EDM) is a state-owned company responsible with exclusivity for the remediation, requalification and monitoring of abandoned mine sites (> 180) in Portugal since 2001. Urgeiriça mine site intervention was scientifically prioritized and innovative techniques were used. EDM opted for ‘in situ’ confinement, followed by geotechnical stabilization, prior to the sealing in a multilayer cover system (clay, polyethylene, geotextile, gravel, sand & soil). Continuous scientific monitoring showed practice was effective, with significant reduction of the superficial radiation. Drainage control on surface & groundwater percolation was also successful, with reduction of the rainwater infiltration and circulation within the tailings. Plants and lawn were placed above the seal, minimizing visual impact. Some of old mining infrastructures were recovered, preserving the mining heritage for leisure & sport.

Resources needed

The total amount spent in the project is around 33 million €, the funding is from regional (ex: Centro Region Operational Program), national (ex: National Strategic Reference Board) and European Union (ex: PT2020) programs

Evidence of success

Continuous monitoring (since 2001) after the remedial works show strong reduction of the radiometry and external radiations from the tailings (500-15000 shocks per second (sps)/ 7,5 μGy/h to below 300 sps/ 0,35 μGy/h), decreased percolation of the rainwaters throw the tailings with consequent reduction of the contamination risk to aquifers or water lines.
This was an applied science project since technical solutions where developed as a result of on site scientific validation of best options.

Potential for learning or transfer

Mining is an old industry and the environmental concerns that exist nowadays were absent in a recent past, not only in Portugal but throughout Europe. Good practices connected to mining can have an important effect on the population and reflect the image of a safe and environmental friendly industry. The use of most up to date scientific knowledge to make the best decisions to remediate contaminated sites is very important to share since same problems affect other EU MS. EDM has performed successfully > 65 cases, mainly in abandoned radioactive mines. The Urgeiriça mine was a challenge and now is a success example, not only concerning the population health and safety but also preserving the mining heritage. This area is in the guide of the Portuguese geological and mines sites’, project promoted by DGEG, to increase scientific awareness of mineral and geological situation and take advantage of the potential for the development of territories with previous extraction activities.