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 nearby rural areas.

Despite not tracking directly over Darwin, ‘Helen’ caused substantial damage to our suburbs, including significant disruption to the delivery of power, water and sewerage services.

In almost every instance damage to the power and water services was caused by falling trees and was not a failure of the power and water 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 services, or uprooting services.

 Power and Water’s response

• At the ‘all clear’ Power and Water crews were out on the roads assessing damage and prioritising restoration.
• The most important priorities were to repair and restore major feeders safely and not endanger the public by energising fallen power lines and house services.
• By late in the afternoon, electricity supply as restored to approx. 12,000 customers.
• By the next afternoon less than 560 properties had no power, 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 power and water supplies as quickly as possible.
• Call Centre staff were called in to Darwin and Alice Springs centres over the weekend to take more than 3,000 customer calls in the first 48 hours.
• Regular updates were given to the community on the status of restoration via print, radio and TV.

Gunbalanya (Oenpelli) flooding 2007 - remote area impact

Gunbalanya is located approximately 330km east of Darwin and 60km north east of Jabiru near the East Alligator River in Arnhemland and has an estimated population of approximately 1100 (including outstations). In early March 2007 a cyclonic low developed into Tropical Cyclone George and caused significant flooding at Gunbalanya, with 930 mm of rainfall over seven days. Rainfall of 311.2 mm on 1 March 2007 was the highest daily total for the area on records going back 93 years. Despite this, the potable (drinking) water supply was operational with no evident damage to the water 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 present.
• Power and Water conducted water sampling that verified the water as 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. Repairs were attended to 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 that 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 on renewing electrical components of the main switchboard which were damaged by water and  contractors continued working 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 programmed to work on manual operation.
• All necessary repairs were completed 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 then made landfall on the northwest Arnhem Land coast, approx. 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 which are 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. The Power and Water Corporation’s 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 but by 10.30am power had been restored to most of the town.
• Power and Water flew a crew to the town and two additional crews drove there to assist with completing 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.
• In Maningrida four Power and Water staff flew to the community to assist 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 and the Community of Jilkminggan was evacuated to Mataranka .

Power and Water’s Remote Operations staff worked in difficult and trying conditions to ensure the safety of our customers, and to ensure that infrastructure and equipment was protected and remained operational. Due to upgrading of intrastructure after the 1998 floods, there was minimal damage to facilities and services.

Power and Water’s response

• Once flood waters had receded houses were assessed by Power and Water Network staff, and customers who had not suffered water inundation had power restored.
• Casablanca Estate had to be isolated due to flood waters inundating our LV Pillars and power was restored after the power infrastructure was assessed by Power and Water personnel
• Network staff isolated the whole of Kalano until water receded, system checked and power was then restored.
• Town water supply was switched from river water to bore water  and systems were monitored. Once water had receded flushing and testing of the water supply commenced.
• 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 being inundated. Electricity was restored by the ESO.
• In Jilkminggan, all systems were checked by remote operations staff via helicopter. The automatic chlorination unit had failed and this was repaired and staff visited the site to flush water supply and chlorinate as necessary.