Engineers work around the clock to avert Benoni dam disaster

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Engineers work around the clock to avert Benoni dam disaster

But one of them warns it could take months to deal with the 'ticking time bomb' at Middle Lake

Journalist


There is panic in Ekurhuleni. The leaking Middle Lake in Benoni is causing chaos, as residents worry that it could end in disaster – and a structural engineer at the department of water and sanitation described the situation as a “ticking time bomb” which could take months to fix.
The huge dam, which borders the N12, broke early on December 23. It is one of four dams lined along the N12 route which are constantly used as recreational facilities by residents.
Since that day, officials from the metro, the water and sanitation department (DWS) and construction workers have been working around the clock to fix the problem.
A structural engineer from DWS said the department could not take risks and allow the metro to work alone on the problem.
“This lake is estimated to have millions of cubic tons of water and had it totally collapsed, many along its way, including other infrastructures like bridges, would have been swept away and cost billions of rands to clean and repair and would take months to be properly done,” said the engineer, who has no permission to speak to the media.
He said the department had to act quickly.
“This is a ticking time bomb and all should work together.”
In joint statement with the metro, DWS spokesperson Sputnik Ratau said danger was averted and lives saved.
“A joint operations committee (JOC) was immediately established on December 23, which helped to prevent loss of lives and damage to properties downstream. The JOC is made up of experts from key departments in the City of Ekurhuleni, Gauteng department of agriculture and rural development, provincial and national department of water and sanitation, and Rand Water,” said Ratau.
Lowering the dam level would help to avoid further erosion on the exposed downstream face of the spillway.
“The lowering of the dam level will assist in allowing engineers access to the damaged slab for repairs ... whilst this is a temporary measure, it is expected that it will take a number of months to complete the refurbishment of the spillway.”
On Wednesday, Ratau said siphoning pumps had been installed to move water from one part of the dam to the other. Ultimately, six such pumps would be installed.
“That process is going ahead successfully. This is to allow the engineers to access to where the damage has happened so they can do the work they have to do ... and also to keep control of the water level.”
Ratau added that they were also looking at how they could reopen access to offramps and onramps near the dam.
“But the most important thing is that the engineers can access the damaged areas.”
Greg Cornelius from DWS said last week that the department had been trying to pump water out of the lake so that engineers could work.
“This is needed to be done urgently otherwise this could have been a disaster that could have cost lives and damaged existing infrastructure,” he said.
Cornelius operates a few of the 10 water pumps that are used to take the water out.
“It’s good that some of the companies are supporting this municipality for free to avert disaster; everyone has come on board to help.”
It is believed that contractors have to lower the lake volume by about 7m to assess the broken collapsing wall, and that this could take up to two weeks.
The operation has resulted in the closure of Bunyan and Tom Jones roads leading to the N12.
When Times Select visited the dam a week ago more than 30 officials and engineers were assessing the damage. The JOC will use six siphon suction pumps to further lower the dam level.
Mayor Mzwandile Masina, who with his mayoral committee members was among those who visited the dam, has pleaded for patience.
“This is a necessary operation to avert a major disaster. We are calling on people of Ekurhuleni to exercise caution and be patient. Once the siphon suction pumps are in place, road usage will resume.”
Ekurhuleni Emergency Management Services spokesperson William Ntladi said they will continue to update the public on the progress of the project.
The metro was swift to place tons of sandbags to avert further damage to the crack after it was reported to them.
But longtime Benoni resident Johan Bezuidenhout said bags of sand won’t solve the problem.
“The residents are panicking as they don’t know what could happen. Ekurhuleni should maintain the infrastructure and must never wait until there’s a disaster. Come next year we don’t want to read in the media about a contract awarded to a wrong company to fix this dam – all should be above board,” he said.
Maria van Rooyen said she was concerned about the birdlife that was being disturbed at this time of the year.
“They are doing their work but there are birds and other ducks that frequent the dam who are affected by this. They must speed up this work and do it properly,” she said.
Downstream, there are no visible housing structures on the banks of the stream.
Lakeside Mall and the Lakeview private hospital are further down but not close to the dam path. The mall borders the Civic Lake which is separated by Voortrekker Street to Kleinfontein Lake. But a few residents, who frequent the Middle Lake Dam to braai, fish or for other recreation, did not quite know what was happening in the lake.
Mara Tau said she has noticed the workers and municipality officers (engineers) at the lake. “First we thought someone had drowned and later we were told that there was a snake that was found there. Little we know that the lake had burst. But we are enjoying this festive time; we don’t really care right now.”
Thembisile Nxumalo, who was with her family, said her only worry was that the bridges that connect the main highways and the town that could be affected.
“If this lake could burst, three bridges down the road could be swept away and this can affect our railway lines as well,” she said.

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