Ecological dambusting in South AfricaPublished 3/7 at 12:32
Selected South African dams, some only decades old, are being removed or made more fit for purpose and environmentally friendly with targeted demolition or rehabilitation. This is in line with an international drive to remove unnecessary man made water catchments to the advantage of the natural life cycle. PDi’s Africa editor Kevin Mayhew looks at the 'dambusters' in South Africa.
The Sasbie River has been improved for the good of its wild life and improved the world famous Kruger National Park (KNP). Teeming with wildlife, it is one of the world’s prime safari tourist destinations. This has been accomplished through a long term series of relatively small scale demolitions of a dam wall, weirs and a windmill on the river.
On the Sasbie River, located in the heart of the KNP, is the Kanniedood dam which was demolished following a three week ‘phase 1’ demolition programme being concluded in April of this year. Phase 2 will be completed next year. The high conservation area has a multitude of free roaming wildlife which attracts thousands of tourists each year, who are able to see the famed ‘big five’ consisting of lion, leopard, white or black rhino, elephant and buffalo.
As an unusual location for a demolition works, the contracting authority, SA National Parks (SANParks), chose to use the South African Army for the demolition work. This is not surprising as the army has a permanent presence in the park. Here they assist the South African Police Service (SAPS) in patrolling the country’s borders with neighbouring countries against illegal immigration, as well as providing back up for anti-poaching activities.
Before the demolition was accomplished, army engineers clearing the affected areas of wildlife as best they could, utilising a spotter aircraft to ensure that no visitors were unwittingly in the danger area of the demolition. Following the demolition by explosive, rubble was removed in order to re-establish a pristine environment in the river where 46 species of fish thrive.
Removing any impediment to free river flow has been lauded by SANParks freshwater ecologist, Robin Peterson, who called the river, “One of the most pristine in Africa, and an extremely important river system in South Africa.” The removal of the artificial barriers (the dams) will enable fish to spawn in traditional, healthy, breeding grounds which means more food for natural predators and people.
One of the companies involved in the demolition of the dams in South Africa is Johannesburg based demolition company Jet Demolition. It has executed controlled demolition and rehabilitation work at various South African dams to varying degrees over the past few years. These include the Hazelmere, Hammarsdale and Midmar dams in KwaZulu-Natal province, and the Grassridge dam in the Eastern Cape Province.
The largest two thus far were its contracts at Midmar and Hazelmere. According to the company’s director, Joe Brinkmann, the work has been exacting; “It tests your ability, experience, capacity and planning when demolishing dam walls. Even more so when one is preparing dam infrastructure for rehabilitation works. Your demolition activities must not jeopardise the integrity of the remaining structures, and must be extensively tailored to suit the extent of rehabilitation required.”
The actual demolition work involved individually assessed and adopted hybrid solutions from the array of available demolition tools and methods. These included blasting, vertical and horizontal drilling, coring, diamond wire cutting, mechanical breaking and specialised machinery and attachments.
Worldwide about 1600 dams have been earmarked for removal or rehabilitation in the interests of fish, birds and other wild life. Originally many were constructed roughshod over fish spawning grounds and feeder river systems that are vital to the survival of many freshwater species.