In 2019, the Kingdom of MOROCCO, in a project of national dimension, has decided to provide a new wastewater discharge outlet to the Rabat/Salé agglomeration. ETERMAR company, which is involved in this field, called us to participate in the removal of the SOLSIF microtunneler. OSS carried out theses underwater works in the median space, between 6 and 20 meters depth.

This type of installation can be briefly described as follows:

• Upstream : A sewage treatment plant.
• Downstream : A discharge outfall equipped with a diffusion zone spread over several hundred meters.

To build the tunnel by which the outfall will pass, it is, at first, necessary to dig a shaft below sea level. Then, once the pit hole is duly completed, the microtunnelling machine will be able to start drilling the passage. The drilling is done horizontally through the natural rock. As the drilling progresses, concrete pipes, brought in piece by piece will cover the tunnel.

When the microtunnelling machine finishes its drilling, it ends its journey in the sand. That’s when our team of divers comes in:

First of all, our divers dredged over the microtunnelling machine to free it completely.

Then, the team disconnected the microtunneler machine. Once all its hydraulic appendages and connection points had been removed, the lifting phase could be started to remove the machine

And finally, a specially adapted lifting beam was lowered and we connected all the slings. The microtunnelling machine was thus safely extracted from the platform.

The challenges

The outcome

The microtunnelling machine has been well extracted and in time. The emissary is now sill operational to this day.