Tricky hydro scheme checks completed

Difficult-to-complete inspections, high up at a water-storage scheme, in KwaZulu-Natal, were easily completed within the allotted time using rope access.

Rope access solutions provider Skyriders marketing manager Mike Zinn notes that the operation – which took place after the conclusion of one of the construction phases at the scheme – focused on the visual inspection of debris and possible defects to eliminate the chances of freak accidents and enable the contractor to comply with operational compliance procedures, which are prerequisites for a hydro scheme.

He emphasises that the shafts were inspected using rope access gear such as rope and head-lights, as well as battery-operated spotlights for clear visibility.

“The shafts were well over 700 m long, 6 m in diameter and with 25˚ slopes. Although it was not easy getting inside the shafts, the project was finished on time,” states Zinn.

He reiterates that some of the common charac- teristics of hydro schemes or water infrastruc-ture projects that have to be circumvented are heights, which include vertical shafts, high dam walls and reservoirs, as well as confined spaces such as narrow shafts and ducting or pipes.

“Both . . . pose a challenge for access, inspec-tion and maintenance,” Zinn cautions.

The hydro scheme will deliver energy to the national grid at peak demand times using hydroelectric power, as it consists of an upper and a lower dam capable of holding about 22-million square metres of water. During peak times, the water is released from the top dam, passing through the shafts into the bottom dam. During low demand, the shafts are used to pump the water back again.

Zinn explains that rope access allows teams with an array of skills – such as inspection, concrete repairs, welding and protective coating application – to access the area where work is needed, swiftly and safely. This is also resource and time efficient, and will allow for the facility to be brought back into service as quickly as possible.

“A three-person team ensured that well over 200 m vertical and almost 1 km of other shafts were inspected.

Zinn notes that rope access allows for quick rigging and derigging of the access systems, and greater flexibility for the team, which consists of three Skyriders employees as well as an engineer from the scheme, who were lowered down the shaft to complete other inspections. The inspections were completed in the alloted two days in the December shutdown period.

“We assisted in getting an engineer conduc-ting various tests into each shaft safely and with the final visual inspection of the shaft concerned, as well as removing possible hazards, such as debris and sand bags, which could cause damage,” he concludes.