(Kaduna River, Nigeria)
Ballard Marine Construction was contracted to install a segmented stop log structure as designed by the Engineer. The extremely remote location coupled with an extreme lack of usable floating / marine equipment in the area required advanced project planning. Ballard elected to utilize engineered “lift” bags in conjunction with winches and guide frames mounted to the intake structure to install this system in place of the traditional larger marine equipment. Once the stop log system was in place, the penstock was dewatered and the Ballard crews accessed the penstock for lintel repair. Once the lintel repairs were made, all equipment and materials were removed from the penstock, and it was flooded. As the water equalized, our commercial divers removed the stop log systems.
Diver depths’ on the project involved mitigating a differential pressure of 70ft (21m) depth. As part of the project Hydraulic diver dredging with a floating containment and water treatment system was utilized.
The existing trash rack was removed along with the hydraulic system, yoke, and cylinder in addition to flushing the internal hydraulic lines of fuel. The hydraulic systems were replaced underwater. In addition Ballard also fastened a 15 degree stainless steel pipe to the upstream dam face.
Once demolition was completed a new trash rack, yoke, cylinder and staff gauge were installed.