The October 2013 bushfires stretched water demand to the limit, with flowrates in the Blue Mountains town of Springwood peaking at around 30 megalitres per day, compared to an average of around four megalitres per day. Sydney Water was well prepared.
Conditions in October 2013 were perfect for a serious bushfire in the Blue Mountains.
The Bureau of Meteorology reported that September 2013 was the warmest on record for NSW. This coupled with high fuel loads, extreme temperatures, dry and windy weather provided dangerous conditions.
The fires that eventuated were the worst in New South Wales since the 1960s. In the Greater Blue Mountains Area over 65,000 hectares (160,000 acres) were burnt out. One hundred and ninety-three properties were destroyed and 109 were damaged in the lower Blue Mountains at Springwood, Winmalee and Yellow Rock.
As part of routine preparations for the bushfire season, Sydney Water carried out a program to locate and ensure the operability of fire hydrants in high risk bushfire areas.
Sydney Water worked collaboratively with the Rural Fire Service (RFS), State Emergency Service, Sydney Catchment Authority and other fire agencies prior to the fire season to ensure operational readiness to deal with bushfires if and when they occurred.
Part of these preparations included the identification of the best points on the water network where water can be reliably drawn by the firefighting agencies. Locations on the larger trunk mains are typically preferred as they are a more reliable source in times of extreme demand, such as during a fire emergency. While it is understood that firefighters will attempt to access any water source when attempting to protect property, if too many tankers attempt to access water from the smaller mains that supply households directly, this can lead to situations where there is no water available for short periods as the capacity of the mains is exceeded.
Sydney Water, through its telemetry system IICATS, has pre-determined Bush Fire Operating Protocols that automatically raised the level in critical water reservoirs to ensure the maximum amount of water possible is available. These protocols are implemented automatically whenever a total fire ban is issued via the System Operation Centre in preparation for potential firefighting.
“Sydney Water systems have been well designed,” said Gary Hurley, Manager, Networks, Sydney Water. “Our system has been robustly designed, with adequate capacity in our storages and built-in redundancy in the pipes and pumps, well supported with critical spares to ensure that the intense demands that eventuate during firefighting can be managed. Of course there are limitations but generally the systems can deal with most situations.
“When we are dealing with active fires we deploy operational specialists to monitor the performance of the system and to make the necessary adjustments so that as much water as possible is directed to the areas of highest priority,” said Mr Hurley.
A demonstration of the demands that developed during the firefighting can be seen from a comparison of a typical day in Springwood where customers may use four megalitres of water per day, compared to the flow rates measured around the time of peak firefighting that equated to a demand of 30 megalitres per day for the same area.
How it worked
To cater for the peak demand in the Blue Mountains area during the fires, the Sydney Water system allowed the operational flexibility to pull water from a variety of sources.
The system is designed to provide water from both the top of the mountains and from the plains below. Water was transferred down the mountains from a small water treatment works located at Cascades, near Katoomba. This allowed water to be supplied as far down as Faulconbridge. A large pumping station located near Penrith allows water to be pumped uphill to areas around Springwood and beyond.
“The 21st of October 2013 was the busiest demand for water in the Blue Mountains area for 10 years”, said Mr Hurley. “Sydney Water specialist operators needed to actively monitor and keep operationally juggling the levels through the Blue Mountains so that water was constantly pushed to areas where it was needed.
“Sydney Water deployed operational staff to work within the fire control centres so that water could be directed to where it was most needed and to coordinate any activity to support the firefighting effort that was required”.
Impact on water reserves
There was no significant impact on water reserves due to the firefighting effort.
Sydney Catchment Authority can move water from as far away as Oberon to provide water to the areas if required.
Eric de Rooy, General Manager, Service Delivery at Sydney Water, said, “Questions are often asked that if Sydney residents minimise their water consumption during periods of firefighting in the Blue Mountains whether that will help with water pressure for the firefighting effort.
“The potential water pressure in the Blue Mountains is established when the system is designed and built and is manipulated by adjusting the level of water in reservoirs in the Blue Mountains. They are a separate system to the system in the city,” said Mr de Rooy
“We should always be water wise and there are water wise rules in place which give people advice on how they should be efficient with water, but the level of water use by people in the Sydney area will not help with water pressure in the Blue Mountains in periods of high demand such as those occurring during fighting a bushfire,” said Mr de Rooy.
As part of Sydney Water’s Priority Sewerage Program, pressure sewerage systems had been installed in a number of outlying areas around Sydney, including 238 at Yellow Rock in the Blue Mountains.
The fire burnt the lids on top of the pressure sewerage system pots located in each property which then fell into the pot, burning the inside of the pot and all other items above the water line. PE pipes and mains also melted and in some cases the heat of the fire burnt through the pressurised main causing leaking sewage to become another hazard in the area.
The loss of the pot lid created an onsite hazard, with a 1m diameter, 2m deep hole appearing in people’s yards. Another major hazard was exposed electrical wires due to the above ground wiring and control box being melted from the heat. Since the area power grid was down, following the loss of power poles to the fire, Sydney Water was able to neutralize this hazard quickly before it became a life-threatening situation when power was restored.
The recovery phase commenced as soon as personnel could gain access to the area.
Generators were introduced to run the wastewater pumping facilities so that system capability could be restored.
The first stage of the wastewater recovery was to repair the systems at the 28 houses that where habitable. The second stage was to make safe the installations at the 56 houses that had been completely destroyed. The remaining 154 properties resumed normal operation as soon as power was restored by the supply authority.
The missing wastewater pot lids and the live electrical wires were seen as the most pressing safety hazards and were targeted to be repaired first.
Damaged water meters where also identified as a priority for repair due to the potential electrical hazard from property earthing systems and the need to restore water supplies to the properties. Sydney Water operations personnel issued bottled water to customers who had lost water services and also kept the locals advised of their actions until we could restore the water to the houses that were still habitable. Water was restored to houses within 24 hours.
Temporary repairs to make safe the damaged wastewater pots was immediately implemented with electricians addressing the electrical risks and plywood covers being used to reduce the risk of falling into open pots where the lid had been damaged. Once power was restored to the area, many of the pressure sewerage systems attached to unaffected houses resumed their normal operation. This required more licensed plumbers to be engaged at short notice to repair leaks in the sewerage system caused by the fire.
Contractors were engaged to re-install the full pressure systems to service the 28 partially damaged properties.
In response to whether or not there was an ongoing issue with water quality following bushfire activity due to the volume of embers and ash that could have entered the major storages, Mr de Rooy said “Sydney Water’s water treatment works are designed to cope with the amount of debris that entered the supply. There have been no issues with treatment in the Blue Mountains during or after the firefighting efforts”.
There was no charge to the RFS for water-use during the firefighting and no charge to local residents.
Sydney Water has engaged an external engineering consultant to review the performance of its water supply system to the Winmalee and Yellow Rock townships during the bushfire event on 17 October. This review will analyse how the water supply system performed on the day and recommend any improvement opportunities that may arise from this analysis.
“This will allow us to identify improvements in operating practices or adjustments to improve system performance,” said Mr de Rooy. “Sydney Water’s job is to support the efforts of the RFS and the community in any way we can.”