Previous cyclones and floods

Cyclone Helen 2008 – urban and rural impact

In the early hours of 5 January 2008, Cyclone Helen, a Category 2 cyclone, passed close to Darwin and rural areas.

‘Helen’ caused substantial damage to our suburbs - including significant disruption to the delivery of power, water and sewerage services - even though it did not track directly over Darwin.

In almost every instance damage to Power and Water services was caused by falling trees and was not a failure of the systems themselves.

At the time of the ‘all clear’ at 6.00am, more than 15,000 homes and businesses were without power.  Damage to the power network included broken high voltage and low voltage conductors, broken or twisted cross arms, bent and twisted power poles and some streetlight damage.

Water and sewerage services sustained less damage, again mostly caused by trees falling on or uprooting equipment.

 Power and Water’s response

• At the ‘all clear’ Power and Water crews were out on the roads assessing damage and prioritising restoration.
• Our priorities were to repair and restore major feeders safely and not endanger the public by energising fallen powerlines and house services.
• By late that afternoon electricity supply was restored to some 12,000 customers.
• By the next afternoon less than 560 properties had no power. These were predominantly in rural areas, which in some cases were inaccessible due to flooding.  Others were individual properties with damage to the service connection to their home.
• Standby generators were used at sewerage and water pumping stations affected by power outages and in some cases sewage pump-out trucks were mobilised to ensure sewage overflows did not occur.
• Power and Water crews worked 12-hour shifts, day and night, over four days to restore services as quickly as possible.
• Call Centre staff were on duty in Darwin and Alice Springs centres over the weekend to take more than 3,000 customer calls in the first 48 hours.
• Regular updates on restoration were issued via print, radio and TV.

Gunbalanya (Oenpelli) flooding 2007 - remote area impact

Gunbalanya is located about 330km east of Darwin and 60km north east of Jabiru near the East Alligator River in Arnhemland and has an estimated population of 1100 (including outstations). In early March 2007 a cyclonic low developed into Tropical Cyclone George. 930mm of rain fell in seven days, with 311mm on 1 March 2007, causing significant flooding at Gunbalanya. The potable (drinking) water supply remained operational with no evident damage to the reticulation system and the water mains had maintained positive water pressure with no evident risk of contamination.  All sewerage pump stations were inundated with flood water.

Power and Water’s response

• A ‘boil water alert’ was issued in case there was contamination.
• Power and Water sampled and tested the water to verify it was safe to drink.
• Waters began to recede on Sunday, 4 March 2007 and Power and Water staff returned to the community on 5 March to assess the water and sewerage situation.
• There was some water damage to the electrical control switchboards that required attention. These were repaired immediately in readiness for when the flood waters receded.
• By Monday, 5 March two main sewerage pump stations were operational and the floodwaters were receding. The two remaining pump stations were still inundated with floodwater.
• Power and Water staff travelled by helicopter to assess the bore field, which had suffered extensive flooding, but there was no damage to the infrastructure or to the power distribution system.
• The bores were operational and there was no threat of water contamination as the bore heads were sealed.
• Power and Water staff and contractors worked to renew electrical components of the main switchboard that were damaged by water and contractors continued on repairs to the telemetry system at the borefield tank.
• Communications between the borefield tank and the main town tank were lost during the flooding and the system was switched to manual operation.
• All necessary repairs were complete within three weeks of the flooding.

Cyclone Monica 2006 – remote area impact

On 24 April 2006, Cyclone Monica moved from the Queensland east coast into the Territory, affecting the small islands north of the Arnhem Land coast as a Category 5 cyclone.  It made landfall on the northwest Arnhem Land coast, about 35 km west of Maningrida, and cut a swath of damage through a number of remote communities including: Yirrkala, Mangarr, Galiwinku, Elcho Island, Ramingining, Ngangalala, Yathalamarra and Millingimbi.

A small but intense cyclone, it also caused significant damage to the Arnhem Land communities of Oenpelli and Maningrida before striking the township of Jabiru.

The majority of damage was to power poles and powerlines.  Power in remote areas is especially crucial as it often runs the bores for water and even pumps to refuel aircraft needed to get essential supplies into these areas.

In most remote communities Power and Water’s local representative is an Essential Services Operator, or ESO. Our Remote Operations staff worked with the ESOs and contractors to restore essential services.

Power and Water’s response

• In the early hours of Tuesday 25 April, the town of Jabiru had no power, power had been restored to most of the town by 10.30am.
• Power and Water flew a crew to the town and two additional crews drove there to help complete the recovery process.
• By Wednesday a detailed inspection of the network had been undertaken.
• A tree trimming program in the township prevented more extensive damage to the network.
• In remote areas damage was repaired and power restored within a day.
• Four Power and Water staff flew to Maningrida to help with repairs, along with electrical contractors.

Katherine/Daly River region flooding 2006 - urban and rural impact

On 6 April 2006 Katherine flooded for the second time in eight years, resulting in hundreds of people being evacuated from homes and businesses. The town was completely cut off due to road flooding. The communities of Daly River, Beswick, Jilkminggan, Binjarri, Barunga and Eva Valley were also affected by flood waters. In Katherine, electricity had to be disconnected to 130 customers due to inundation or where inundation was imminent. Community members from Jilkminggan were evacuated to Mataranka.

Power and Water’s Remote Operations staff worked in difficult and trying conditions to ensure the safety of our customers and ensure that infrastructure and equipment was protected and remained operational. There was minimial damage to facilities and services, which had been upgraded after the 1998 floods.

Power and Water’s response

• Once flood waters had receded, Power and Water networks staff assessed houses and customers who had not suffered water inundation had power restored.
• Casablanca Estate had to be isolated as flood waters had inundated our low voltage pillars, power was restored after the infrastructure was assessed by Power and Water personnel
• Network staff isolated the whole of Kalano until water receded, system checked and then restored power.
• Town water supply was switched from river water to bore water and systems were monitored. Once water had receded we started flushing and testing the water supply.
• All sewer pump stations were monitored and pump stations that were inundated continued to run. All sewer pump station switchboards were clear of flood waters.
• A sewerage dump point was required for travellers and Power and Water liaised with Environmental Health.
• In Mataranka properties either side of the Little Roper were isolated by the Essential Service Officet (ESO) due to inundation. Electricity was restored by the ESO.
• In Jilkminggan, all systems were checked by Remote Operations staff via helicopter. The automatic chlorination unit had failed, this was repaired and staff visited the site to flush water supply and chlorinate as necessary.