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By Faizel Patel

Senior Digital Journalist

Joburg CBD explosion: The 3 possible causes identified by the City

The Joburg city manager said the buildings on either side of the Bree Street blast are structurally sound and there is no need to evacuate.

Technicians believe the cause of the Bree Street explosion, in the Joburg CBD, is a collection of gases that built up in the sewerage system, Joburg city manager Floyd Brink said on Thursday.

Brink led a technical media briefing on Thursday on the preliminary findings of the investigations into explosion in Johannesburg.

The blast on Wednesday afternoon claimed one life and injured 48 others.

Thirty-seven vehicles, most of them taxis, were also damaged during the explosion, which destroyed sections of Bree and Rissik streets.

Brink said city engineers and specialists from Johannesburg Roads Agency (JRA), Johannesburg Water, City Power and representatives of eGoli Gas have been on the site to ascertain facts on the source of the explosion and the triggers.

Cause of explosion

He said preliminary investigations have presented three possible scenarios for the explosion.

“These are; ignition of methane gas in underground storm water systems due to sewerage ingress, the ignition of natural gas, mixed with air (oxygen) in underground storm water drainage systems or service ducts and the third and last possibility, is the ignition of gas from a gas pipe burst.

“At this stage the only potential cause appear to be warranted, accidental leakage of natural into the service duct reaching explosion concentration levels of 5-15% and was ignited by a source unknown at this stage. The source of gas in the service duct is unknown. Investigations in this regard will continue to try locate the source over the next few days,” Brink said.

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Air quality

Brink also said the buildings on either side of the Bree Street blast are structurally sound.

“At this stage, there is no need to evacuate the buildings in the area and as stated, Joburg Water will provide mobile water and sanitation services to residents in the area.

“We have also assessed the gas leaking into the atmosphere and have been assured by the Environmental Services and Air Quality Controllers of the city that the gas leaking into the atmosphere poses no risk to residents and as its concentration reduces rapidly in open air. However, gas leaks into subsoil cavities such as basements can be fatal,” he said.

Back to normal

Brink added a multi-disciplinary team is working around the clock to secure the site, conclude investigations and restore services for residents in the area.

“The tasks we are undertaking are complex and at this stage will have to be handled with due care, and that no heavy equipment can be deployed to the site immediately. The digging and trenching to be done now will have to be done by hand until we are confident the site is safe and all hazardous factors are cleared.”

Brink expressed his appreciation to the first responders from the city of Joburg along with the private sector and Johannesburg Chamber of Commerce, who supported the city in response to the explosion.

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