Ongoing investigation moves focus to bulk water system

TasWater’s investigation into taste and odour issues is progressing with operations and maintenance teams having isolated systems to clarify areas of concern.

The isolation of the separate systems will build a clearer picture of impacted areas as customer service officers embark on a focused campaign of call backs over coming weeks to analyse areas of improvement.

TasWater General Manager Works Delivery Dr Dharma Dharmabalan says the investigation team is working through an enormous amount of data.

“We have been studying the source water and flow data from all of the systems and modelling them against the areas where the customers have contacted us about taste and odour issues,” Dr Dharmabalan said.

“Part of our investigations are focused on how the three water sources of Mt Wellington, Lake Fenton and Bryn Estyn have interacted with the West Derwent line over the past six months,” Dr Dharmabalan said.

The West Derwent line is the major source of water for Hobart supplying around 80% of the area along both sides of the river. This system is having a thorough investigation from the raw water at its source, through to the Bryn Estyn Water Treatment Plant, reservoirs and bulk mains.

As a part of the management of the taste and odour issue, TasWater teams are conducting a systematic inspection and cleaning of reservoirs such as those located at Box Hill in the Derwent Valley.

The three Box Hill Reservoirs are nine mega litres each and water is pumped to them directly from the Bryn Estyn treatment plant. They are used to store water and pressurise the West Derwent system.

“Our focus is to ensure the water remains safe to drink and we continue to take water samples through all systems each day with a team of samplers currently rotating through a seven day a week
roster,” Dr Dharmabalan said.

Although these developments are a positive step, Dr Dharmabalan reiterates that the investigation to identify and locate the source of the problem continues.

“We have engaged with specialist interstate laboratories which are conducting a broader range of tests to help identify if there are other potential sources of the issue. These tests are very complicated and take a number of days to get results,” he said.

The volume of calls into the TasWater call centre have reduced from a peak early in the week but it is too early to tell if it is a definitive sign that treatments are working.

Anyone experiencing irregularities in their water is urged to call the TasWater call centre on 13 6992.

Updates on the situation are on the TasWater website http://www.taswater.com.au/Community—Environment/Current-Alerts/Taste-odour-updates

Background Information – Hobart’s water supply

Number of complaints received by TasWater:
 346 since 1 January; the majority in the past week.
Greater Hobart’s three primary water catchments:
 River Derwent, through Bryn Estyn Water Treatment Plant – around 60% of supply, supplying Greater Hobart, Glenorchy, eastern shore and Sorell, and Bridgewater, Kempton & Campania
 Lake Fenton – through Bryn Estyn Water Treatment Plant – around 20% of supply for parts of Glenorchy and Hobart
 Mount Wellington – around 20% of supply for parts of Glenorchy and Hobart an all of Kingborough
Treatment facilities
 One water treatment plant – Bryn Estyn Water Treatment Plant (located outside New Norfolk)
 16 dosing stations (disinfection)
Storages
 Nine reservoir dams in the supply system
 96 storage sites (excluding those in water treatment plants)
Bulk water mains (pipelines)
 419 km in length
 Average age 52 years; earliest records go back to 1917
Reticulation pipelines
 2,172km in length
 Average age 34 years; earliest records go back to 1920
No. of connections in greater Hobart
 85,218
Number of drinking water tests
 6,100 per annum
Number of water test sites
 80
Simon Pilkington, TasWater