Vale (NYSE:VALE) said on Monday it was closely monitoring its Gongo Soco mine, in the southeastern Brazilian state of Minas Gerais, as an embankment at the facility continues to erode, following heavy rainfall.

The world’s no. 1 iron ore producer said the northern slope at the mine, halted since 2016, continues to slide into the structure, a process that has been taking place gradually over the past year.

The Rio de Janeiro-based miner said it was watching for any impact the erosion could have on the Sul Superior mining waste dam about 1.5 km (0.9 miles) from the slope area. This structure remains at Level 3 watch, the most critical level that indicates a dam burst is “imminent or underway.”

The pit and the dam are remotely monitored 24 hours a day, using radar and a robotic station capable of detecting millimetric movements, as well as by drone surveillance and by the Geotechnical Monitoring Centre.

The news comes 14 months after the collapse of a tailings dam at the company’s Córrego do Feijão mine in the town of Brumadinho, also in the state of Minas Gerais, which killed more than 250 people in one of the world’s worst mining disasters.