The third phase began as a natural continuation of four years of cumulative collaboration at the Bomboré site. The employer's operational requirement was a volume increase that would outpace the rate of waste generation; for us, this meant working on parallel fronts — subgrade acceptance, geomembrane deployment, and welding stations were progressed simultaneously in different cells.

The most critical site-specific engineering issue was the risk of differential settlement that could occur under long-term load over lateritic soil. Therefore, the grammage and mechanical strength values of the geotextile protection layer placed under the HDPE geomembrane in the liner package were selected particularly high, and the deployment schedule was rescheduled according to the moisture balance of the subgrade after the rainy season.

A hands-on training program was conducted for local technicians regarding the automatic welding machines brought to the site in this phase; Yesti's emphasis on knowledge transfer in West Africa continues to directly contribute to the localization of team capacity.