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Thursday July 15, 2010


Scientists colour Darwin Harbour in tidal study

A rose-coloured plume stretching for about half a kilometre may be visible on Darwin Harbour tomorrow morning as scientists take to the water to conduct a tidal study.
As part of the closure of the Larrakeyah outfall, Power and Water will extend the existing East Point outfall.
Power and Water has been working with internationally recognised expert Eric Valentine, who is the Professor of Civil Engineering at Charles Darwin University, in the design of the new outfall.
Power and Water is coordinating the tidal study with experts from Charles Darwin University (CDU) and the Australian Nuclear Science and Technology Organisation (ANSTO).
Tracers will be released into the water about 1km from East Point and then monitored by the team of scientists from boats and a helicopter.
While computer modelling shows rapid dispersion of treated wastewater due to tides in Darwin Harbour, this study will calibrate that model and help determine the best location for the outfall.
The outcomes of the study will be incorporated into a Public Environment Report which should be completed by the end of this year.

East Point outfall tidal study

What is happening?
Power and Water is undertaking a study at East Point to improve our understanding of tides and currents in this area of the harbour.
Why are we doing it?
Power and Water has been working with Charles Darwin University (CDU) for about five years to develop a hydrodynamic water quality modelling tool to help predict the dispersion of treated wastewater discharged into Darwin Harbour. This study will help calibrate and validate that model.
What is the model used for?
It will be an important environmental assessment tool, used to help plan improvements to harbour outfalls.
In the short term, Power and Water is closing the Larrakeyah outfall and diverting the sewage from the Larrakeyah catchment to the Ludmilla Wastewater Treatment Plant. Treated wastewater will eventually be discharged to East Point.
The existing East Point outfall will also be extended and this modelling will help determine the best location for the extension.
Who is doing the study?
This is a collaborative effort with the Australian Nuclear Science and Technology Organisation (ANSTO) and CDU. Internationally-renowned experts from these organisations are helping deliver the study for Power and Water.
When and where is the study?
On Friday 16 July and Saturday 17 July. The tracers will be released in the harbour about 1km from East Point.
How will this study work?
Two tracers – Technetium-99m and Rhodamine WT – will be released into the water.
Technetium is a radioisotope widely used in nuclear medicine, where it is injected into patients. Rhodamine WT is a rose-coloured water-tracing dye that has been used in a number of other environmental studies in Darwin Harbour.
The tracers will be released from a boat into the water just after high tide, on an outgoing tide.
The movement and concentration of each tracer will be monitored using highly specialised measuring probes mounted on two boats. They will spend two to three hours tracking the tracers as they are diluted and dispersed by tidal currents.
Aerial photography will be used to track the visible tracer.
The figure below illustrates the predicted dispersion and movement of the tracers (highlighted in yellow) over time after they are released into the ocean.

15 minutes after injection 30 minutes after injection 60 minutes after injection 90 minutes after injection

Will this impact the Harbour?

Power and Water has undertaken thorough environmental and health risk assessments and the necessary regulatory approvals have been obtained to undertake the tidal study.

The Darwin Port Corporation has declared and advertised an exclusion zone around the study area.

I hope they don’t use Rhodamine or other similar dye like the NSW EPA used to do.
We used it on several major operations to detect the source of pollution.
.
The scientific branch gave us the dye and told us how to use it and that it breaks down in sunlight. They forgot to tell us it was also toxic until after we had used it.

Matt Flynn wrote: ..........

How will this study work?
Two tracers – Technetium-99m and Rhodamine WT – will be released into the water.

nomad wrote:I hope they don’t use Rhodamine or other similar dye .....

.... you could at least read the article.. :-/

I read it but missed it. thats what happens when you get old

Why dont they just fit a tracking collar to a turd at the poop shooter and track it?

Why dont they just fit a tracking collar to a turd at the poop shooter and track it?

Bwahaha, I thought the same, except they could use a box of Chokito bars to make it less unpleasant, and put a flashing LED on each one. Was it a Chokito or Polywaffle that had them all fooled in Caddyshack?

The scary thing is

Who is doing the study?
This is a collaborative effort with the Australian Nuclear Science and Technology Organisation (ANSTO)

Didn't think there were that many Indian resturaunts in Darwin