The Kariba Dam Rehabilitation Project.

17th Aug 2020

Standing 128 metres tall and stretching 579 metres as it spans the powerful Zambezi River, the Kariba Dam is undergoing refurbishment to ensure its continued safe operation. The dam was constructed over sixty years ago and holds 185 cubic kilometres of water and generates electricity for parts of Zambia and Zimbabwe. A requirement for refurbishment was identified during routine monitoring of the dam. The Kariba Dam Rehabilitation Project will focus on two areas – the refurbishment of the spillway and reshaping of the plunge pool.

The spillway consists of six sluice gates which enable water to be released from the dam to manage the water levels. When exposed to water, concrete undergoes minor expansion. After decades of the dam’s operation, this expansion is approaching a point where the smooth operation of the sluice gates could be affected.

As water gushes from the dam’s spillways, the sheer force as it enters the waters below creates erosion on the river bed. This erosion has created a deep pool at the base of the dam and there is potential for the erosion to reach the dam’s foundations with the inevitable consequences. To remedy the situation the plunge pool wall will be re-enforced.

The Spillway Refurbishment
Aquaforce Concrete Services will support Freyssinet International with the huge task of removing 1,000m3 of concrete from the six dam sluice gates.

To remove the concrete without damaging the underlying rebar or the surrounding metal infrastructure, hydro demolition methods will be employed. Hydro demolition uses a high pressure jet of water at a pressure, normally above 1000 bar, enabling concrete removal faster than using a jackhammer but without affecting the metal rebar. Where the mechanical impact of a jackhammer can cause small cracking in the surrounding healthy concrete, hydro demolition affects only the concrete that it comes into contact with.

The vibrations jackhammer users will be all too familiar with are almost eliminated with high pressure water jetting; Recent Hand Arm Vibration (HAV) legislation has led to a huge increase in the use of high pressure water jetting for concrete removal applications. Furthermore, with hydro demolition, operators benefit from reduced noise and dust. The finish achieved with hydro demolition gives a surface which is ideal for bonding between old and new concrete. In addition to the benefits already mentioned, hydro demolition is, quite simply, much quicker than traditional techniques.

The Equipment
The project will require both manual hand lance and robotic methods of concrete removal. Calder will supply the high pressure pumping and filtration equipment. The Calder scope of supply includes:

2 x Containerised Pump Units
Each unit is mounted into a noise-attenuated container and features the Hammelmann HDP500 series reciprocating plunger pump. Driven by a Volvo engine, each unit will deliver 262 lpm at 1040 bar.

2 x Trailer Pump Units
These units are mounted onto road-going running gear. The Hammelmann 200 series pump is driven by a Cummins diesel engine and each unit has a performance of 110 lpm at 1000 bar.

2 x Containerised Water Filtration System
These filtration systems allow the water used for the Hydrodemolition process to be reused or cleaned up to a quality that will allow the water to be returned to its source, in this case back to Lake Kariba.

Operation and Maintenance Training
Operation and maintenance training are included in this project. Our Life Cycle Services team offer familiarisation and training courses, and full service and spares support.

For more information on our high pressure waterjetting equipment click here

To talk with a sales engineer about your application, please call +44 1905