The electricity part of ActewAGL had to first to energise as much of the system as possible around the damaged infrastructure, and then to achieve several months worth of repairs in a matter of days, all while paying close attention to safety.
Working with damaged high-voltage infrastructure is challenging at the best of times.
System control staff isolated and bypassed damaged parts of the system so they could restore supply immediately where possible. This began even while the fires were still passing. Workarounds were devised, temporary lines run, little used switches and controls were brought into play, and the system was stretched to the limits of its engineered capacity. This was done with due regard for safety.
The infrastructure repairs began at first light on Sunday morning. There were not enough people or materials to do the repairs. So while ActewAGL’s crews were being dispatched to undertake critical repairs, the call went out across south-east Australia for people and trucks, and for materials including poles, transformers, mini-pillars and switch-gear. This was a massive management and logistic challenge. It was essential that the first crews arriving in a few hours could be put to work safely and without delay. Every technician, truck and pole that arrived in the ACT over the following days was used without delay.
ActewAGL had to “engineer on the fly” using whatever resources available.
Where replacement poles were available they were used. Where they weren’t, cable was run from adjoining buildings and poles to provide a temporary service. In some places sections of line were eliminated and re-routing undertaken.
This process was in many cases a temporary expedient, and as more poles and transformers became available they were installed.
In one case all the poles across a small valley had burned, so power lines from the top of one peak to the top of the next. This had never been tried before in the ACT, but it was done successfully and remains in place.
At the peak of activity 350 ActewAGL staff and 150 staff from other utilities were working. Providing food and lodging became a major exercise.
The water division had to restore treatment plants, make safe the water supply from the damaged Chapman reservoir, and later to monitor and ensure the safety of the dam water supplies.
When the electricity supply was reconnected on the night of the fire the plants resumed normal operations.
Restore the sewage treatment plant to full operation was more difficult. Critical power and control cables had been destroyed as a result of the fires entering drains, ducts and trenches that were inaccessible to the plant operators fighting the fires.
Immediately after the fire, sewage was diverted to the by-pass storage dam. It began to fill. An urgent message went out to residents to cut the amount of liquid entering the system. Input was cut by up to 50 per cent.
But specialist cables required to restore the plant might not be available for weeks.
So all the undamaged cable was removed and rerouted and power was restored to three of the four disabled processors. A job that should have taken weeks was done in less than three days.
No untreated sewage was released to the Murrumbidgee River.
At the Chapman reservoir, the roof and its nine-tonne steel frame were gone. Debris and ash made the water undrinkable. So the reservoir was by-passed and water pumped direct from the mains supply to sections of two suburbs. A “boil water” alert was issued to residents and bottled water was distributed.
The reservoir was inspected, the debris and ash removed, and a water testing and chlorination plant was installed close by to provide additional disinfection during the time when the roof was off. The new roof was completed in June.
With gas, the supply to 6,500 households was cut as a safety measure on the evening of the fire. Supply was restored to 500 households the day after the fires.
Restoration of supply to the remaining 6,000 households in Weston Creek was dependent on safe isolation of damaged services, and safely refilling the network which had been emptied of gas by the fire damage to customer meters.
Damage to the network principally involved ground level fire damage to customer supply pipes and meters. Supply could not be restored until every damaged line and meter had been isolated. This required a gas maintenance team to physically excavate, disconnect and safely terminate over 300 gas supplies to properties either with damaged meters or where the property itself was damaged.
This took less than 48 hours, and then the process of restoring gas to a complex network of mains and customer supplies began. Every one of the 6,000 properties had to be isolated. Gas was then introduced into each network section, and the system pressurised for 24 hours to ensure there were no leaks. Each household’s isolation valve was then turned on, each customer’s gas installation was inspected to ensure there were no leaks, and appliances were relit at each customer’s premises. Supply was fully restored by the weekend following the fires.
A year’s work was done in nine days.