Regarding Fire Risk in Waratah

In response to a Question Without Notice from the Member for Murchison, the relevant Minister advised that TasWater has been told by the Tas Fire Service that they do not view the Reservoir as critical to their firefighting efforts in the town or nearby and that there are a number of water sources that they use which will be unaffected.

Every resident of Waratah would be interested to see the minutes of that TasWater / TFS meeting. If there are no such records, we can probably assume that no such formal meeting ever happened.

Waratah Reservoir and its Geology

Now for some reality.

Consider what happened on the mainland with the bushfires: Even rainforests became part of fire storms. Waratah can be considered a township on an outlier of the north western highlands, terminating at Mount Bischoff, the original tin mine. Its geographic position, as well as the unconscionable damage caused by TasWater to Waratah Reservoir exposes Waratah to extraordinarily severe bushfire threats.

Without its reservoir Waratah River becomes an ephemeral stream. Waratah Reservoir is situated on a basaltic rock base, with an overlay of sand, loams and gravels. The reservoir controls the ground water level of its catchment and stores moisture in the surrounds of the reservoir. This is evidenced by the rainforest rim around the reservoir, and the ‘water tunnel’, a sub-surface interception drain, built by the founding fathers of the town to harvest such sub-surface flows for industrial use.

Water harvesting in Waratah.

During dry parts of summer, as evidenced during 2019 and 2020 Waratah Reservoir’s severely lowered spillway stops spilling. The lowered reservoir level reduces the volume of stored subsoil moisture and related flows; and during low-rainfall summers the spillway can stop spilling after only a few days of no rain. By contrast higher than currently possible reservoir levels are associated with higher subsoil storage volumes, which continue to percolate into the reservoir, keeping the spillway and Waratah River flowing for extended periods of time during dry summers.

Continued retention of the existing spillway level (approximately 2 m below previous maximum supply level) has already severely reduced the certainty of Waratah Lakes’ current average water levels during dry summer periods. Removal of Waratah Reservoir Dam (TasWater’s perceived ultimate victory) will expose the ephemeral nature of Waratah River during summers, and leave Waratah without adequate flows to maintain the levels of Waratah Lakes, consequently leaving Waratah without fire-fighting capabilities, when the bush-fire threat is greatest.

2019 TFS Incident

Last year there was a fire on a residential block in the western part of Waratah. This was not a distinctive bushfire; but there was the danger of the fire escaping from a residential block into the adjacent non-productive forest and getting away from Waratah, into areas of forest, not accessible by vehicular fire units.

Consequences were as follows:

  • Hydrants were too far away from the fire to be used for direct fire-fighting.
  • It was uncertain if the 1000 litre Waratah fire unit was adequate to manage this fire (between re-fills) by itself – safely.
  • For town-safety a number of units from adjacent townships as well as a helicopter were called to extinguish the blaze.
  • The level of water in Waratah Lakes dropped to such an extent that the water supply pump at the Water-works ceased sucking up water and hydrants stopped to provide water for the fire-fighting units.
  • TFS units had to find hard-surfaced access for re-filling from Waratah Lakes. This effort was complicated by having to find access to the lakes, avoiding areas over-run with tourists; but water deep enough for the suction pumps to operate.
  • The fire was extinguished.

Well done and lucky – that time…

Waratah’s Bushfire Exposure

Please refer to the appended map. Waratah is situated on a spur of Tasmania’s north-western highlands. The northern and western sides of Waratah are delineated by 200m to 300m deep valleys, with descending slopes varying from vertical to 1 in 5 and the majority of valleys averaging between 1on 2 to 1 on 3. Waratah Waterfall (Happy Valley) extends into the centre of town with a sheer cliff on its eastern side and average slopes of 1 on 1 to 1 on 2. Steep slopes, shown in light olive green on the attached topographic map denote covers of non-productive forest and undergrowth.

During bushfires these areas will be inaccessible by vehicular units; and with electrical storms during summer; nature-caused bushfires will race up Waratah’s western and northern slopes, terminating in the centre of Waratah. The fire’s actions will be accompanied by ember sprays well in advance of the bushfire, leaving little response time for our 1000-litre (= 6 bathtubs of water) local fire-fighting unit. Chances are that during such high fire-danger season, other fire crews with their units will be busy with their own fires or on alert to protect their own brigade area.

In the east Eucalyptus nitens plantations provide highly flammable fuel. With the buffer of Waratah Reservoir and its rainforest rim removed, fires from eastern and southerly directions will have easy ingress into Waratah.

A thought experiment: How much time does it take for a rainforest tree to sink its roots another two metres? Will it die trying?

The current evacuation plan for Waratah (Near the Men’s Shed) needs changing, if Waratah Reservoir buffer is removed.

This material was provided by Helmut Ernst, founding member Friends of Waratah Reservoir incorporated, firefighter – volunteer with the Waratah fire Brigade

To be added:

The Climate

  • Meteorological forecast for the next 10 years with the reference point used being the 2020 mainland bushfires (as baseline)
  • Review of my report by fire catastrophe-hardened bushfire assessor(s?) from Mainland

Scenarios

  • Power failure in Waratah
  • Cut off of Waratah due to bushfires

Potential countermeasures

  • High-volume water tanks in strategic positions – number of tanks with necessary volumes to be assessed by bushfire hardened Fire consultants from the mainland.
  • High pressure diesel water-pumps with adequate strength to deliver water for wetting down foliage of vegetation in valleys when and as needed
  • Adequate foam to suppress approaching fires (volume to be determined by mainland consultant)
  • 10 000 to 20000 litre water tanker to run shuttle service to top up stationary tanks at pump sites.
  • Active advertising to attract more bushfire volunteers.
  • Advertising to promote domestic fire training and protection: gutter guards, clearing of yard, domestic fuel driven pumps with appropriately sized domestic tanks as well as advertising as to how and when to use them.

Installations like these on top of Mount Stromboli near Canberra would have saved many millions of dollars in bushfire damaged telescopic arrays. By contrast, worst case scenario for Waratah could be impacting possessions as well as health and lives of any number of its 300 residents.

BUT THE MOST IMPORTANT OF ALL – REMEDIATE THE DAM TO FULL CAPACITY AS PER THE PROPONENT SUBMISSION!!!

The behaviour of the state government, the relevant ministers, and TasWater reminds me of that famous Monty Python sketch in the Life of Brian.

‘WHAT HAVE THE ROMANS EVER DONE FOR US?’