Testing dye yet to turn up

Theory tested: Rockwater principal hydrogeologist Dr Peter de Broekert releasing the dye at the site on Friday, July 19. Photo: Jesinta Burton.
Theory tested: Rockwater principal hydrogeologist Dr Peter de Broekert releasing the dye at the site on Friday, July 19. Photo: Jesinta Burton.

The Shire [of Esperance] is hesitant to spend further resources until the physical properties, such as groundwater flow, of the site are scientifically confirmed.

Shire of Esperance chief executive officer Matthew Scott.

A critical test to determine the time it would take leachate to travel at the proposed Kirwan Road tip site is yet to yield results, more than two months after it was first conducted.

On July 19, Rockwater principal hydrogeologist Dr Peter de Broekert released non-toxic dye into two 13-metre nests, each of which have three monitoring bores.

The experiment is designed to determine the site's groundwater transport parameters, while testing the theory that it would take more than 41 years for a contaminant to travel 1.6 kilometres to the southern boundary, as calculated by a pump test late last year.

After conducting the tracer test, Dr de Broekert said that, based on the data collected to date, he predicted it would take several months for the dye to be detected in one of the monitoring bores.

Speaking with the Esperance Express, Shire of Esperance chief executive officer Matthew Scott said the tracer dye had not yet been detected in any of the control bores on the site, so far confirming Dr de Broekert's theory.

It is understood that six trained staff have been conducting the tests weekly since the dye was released into the bores on July 19.

The results of each test are then sent to hydrogeological consultant Rockwater for interpretation.

Mr Scott said the shire expected the dye plume to reach the bores in the near future but was not willing to speculate when that may be.

"It's a simple process, a water sample is taken from the bore using a bailer, a portion of the sample is poured into a cuvette and the cuvette placed into the Aquaflore device," Mr Scott said.

"It will appear when the dye plume reaches the bore, we expect that to be sometime in the near future, however an accurate time cannot be determined.

"The monitoring bores will continue to be checked until the tracer tests are completed, as in the dye plume has been identified to have reached the monitoring bores.

"We are currently testing other bores on the site as a control."

The test is a crucial part of the 41-step process to satisfy the elements of the Environment Protection Authority's Public Environmental Review of the proposal.

With the total spend at the site expected to reach more than $300,000 by the end of the process, Mr Scott said the council had vowed not to start the next test until this one was complete.

"This [completing the steps] is heavily dependent on when the tracer tests are completed and therefore we cannot provide an estimate," he said.

"The shire is hesitant to spend further resources until the physical properties, such as groundwater flow, of the site are scientifically confirmed.

"This being said, many of the of the other steps are around developing management processes and policies for the site, which are relatively low cost."