Your browser is no longer supported

For the best possible experience using our website we recommend you upgrade to a newer version or another browser.

Your browser appears to have cookies disabled. For the best experience of this website, please enable cookies in your browser

We'll assume we have your consent to use cookies, for example so you won't need to log in each time you visit our site.
Learn more

Huge repair programme needed

ENGINEERS CONFIRMED that it will take at least three weeks to bring order to the chaos created by the fire above ground.

Critical is the intersection of Howard and Lombard Streets which is just 1.5m above the crown of the tunnel. A 1m diameter water main has to be squeezed through the gap.

Three hours after the fire started, the heat was enough to rupture the main, flooding offices and hotels nearby and causing a loss of pressure throughout the city.

Some 250M litres of water were lost in the first four hours after the break, as engineers from the Department of Public Works (DPW) struggled to isolate the main.

A seized valve prevented the engineers from fully halting the flow until the weekend when a new valve was cut in. Work to replace the ruptured section of the 50 year old main itself had to be called off entirely after parts of the tunnel began to collapse on the fire crews working below.

Further investigation revealed that the outer ring of the two-layer brick tunnel had been removed to accommodate the main in the 1.5m separating the crown of the tunnel from the road surface above.

Repairing the main is the top priority, and work is now well under way to replace a 20m section of the cast iron structure with a 910mm ductile iron pipe.

To limit disturbance to the tunnel's brick arch, DPW engineers intend to leave the existing main in place and use it as a cradle for the new main.

This work is hindered by the rails of the Mass Transit Authority's light rail system, which cross the 20m section to be replaced. MTA rules usually prohibit other operators from working within 3m of its tracks, let alone remove them.

However, the MTA has given special dispensation for the DPW to proceed.

Once the main is repaired attention will turn to the road itself, with several areas having subsided under the intense heat from below and torrents of water from above. At least one storm drain is also known to have collapsed.

Have your say

You must sign in to make a comment

Please remember that the submission of any material is governed by our Terms and Conditions and by submitting material you confirm your agreement to these Terms and Conditions. Please note comments made online may also be published in the print edition of New Civil Engineer. Links may be included in your comments but HTML is not permitted.