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.