Maceió, July 2, 2019 - Almost 300 professionals from 13 national and international companies work in sonar studies in the rock salt extraction wells of Braskem in Maceió. The analyses are considered  essential to the understanding of what happened in the districts of Pinheiro, Mutange and Bebedouro and to propose definitive solutions to ensure the safety of the residents of the region. There are in total 35 wells, and currently they are all out of operation.

The company intensified the inspection works to conclude the studies in all the wells by the end of the year. So far, the sonars in 12 wells have been concluded and they confirmed that the mines have the expected conditions. Only one of them received a new stability condition. 

Six probes are used simultaneously, one for each cavity, however, there are some warped pipes that hinder the access of the equipment. A new probe is under negotiation, reaching the maximum allowed as per the guidelines of the companies.

In cases of more complex warping, a new technology is being used in the process to expedite the process and allow the conclusion of the activities. Companies hired by Braskem make perforations that are parallel to the pipelines as an alternative to allow the sonar equipment to go down until the depths of 900 and 1200 meters to the interior of the cavities. The process is safe and is in accordance with  international safety standards: once the well is concluded , the drilling in the soil is closed.

Sonar is the technique that verifies diameter, height, volume and  allows the monitoring of the situation in the cavities. The equipment is introduced through a cable and then winched to the depth of the well, from where it emits sound waves that propagate in the water, reflect in the walls of the cavity and then return to the equipment. The distances are calculated according to the sound velocity.

The study is outsourced and performed by French company Flodim, a world-reference company in sonars. Around the world, several companies that work with dissolution mining use the sonar, the only method that allows measuring the dimension of the cavity.