SAVE RALPHS BAY, First expert testimony at canal estate hearings, June 23
Yesterday, Monday June 22nd, Save Ralphs Bay Inc. called its first expert witness in the RPDC Hearings into the Walker Corporation’s proposed Ralphs Bay canal estate.
Dr. Ruth Eriksen explained the “Ralphs Bay conundrum” – the fact that, while Ralphs Bay sediments may, under some testing regimes, show low levels of heavy metal contamination, the mercury levels in Ralphs Bay food chains are often alarmingly high. For example, the levels of mercury detected in Ralphs Bay flathead are among the highest to be found anywhere in the Derwent estuary.
Dr. Eriksen called for further testing to be carried out into the bioavailability of heavy metals such as mercury, and expressed her concern that the long-term mobility of heavy metals was poorly understood at present. This means it is difficult to say whether or not oxidative release of heavy metals into the environment would be a problem in the proposed development in the long term.
Dr. Eriksen emphasized that current best-practice guidelines for assessing environmental toxicity adopt a “weight of evidence” approach in which
site-specific information may trigger further investigation.
The Walker Corporation’s lawyer, Mr. Gunson, pressed Dr. Eriksen to agree that the development could be approved subject to additional monitoring.
However, Dr. Eriksen’s professional opinion was that further test results should be taken into account before the RPDC makes its final recommendation.
Under cross-examination, Dr. Eriksen said, “I would like to see more information on the nature and spatial distribution of contaminants in the navigation channel sediments, because I am concerned about their behaviour in the bund and in the final built form of the development, and the long-term oxidation and release of metals in the development. This hasn’t been addressed in the investigations so far.”
Dr. Eriksen is a co-author of the Water Quality Improvement Plan for Derwent heavy metals (WQIP, 2007).
In other news from the Hearings on Monday, the Walker Corporation’s noise expert, Matthew Bryce agreed that noise levels during construction would exceed guidelines. Mr. Bryce admitted that he did not do any monitoring at the Lauderdale school, but he said the modelling suggests the school would not experience annoyance in the classrooms – if the windows remain closed.
A 3m high noise barrier of solid material would be erected at the edge of
the development site along the Lauderdale foreshore.
“The erection of this noise barrier would cause an immediate, significant and long-term loss of visual amenity for local residents travelling past the northern section of the Bay, if the proposed development went ahead”, said SRB spokesperson, Jane MacDonald.
The Walker Corporation’s air quality expert, Mr. Ronan Kellaghan, admitted that Walker Corporation’s wind data was incomplete and that, owing to a lack of site-specific data, measurements from the Hobart airport had been used in the modeling of pollutant dispersal. Furthermore, 2006 data had been used and hence recent high wind levels were not included. Mr.
Kellaghan admitted that the use of site-specific wind data from Ralphs Bay would have been preferable. He did not speak to local residents about wind
conditions in Ralphs Bay before conducting the modeling exercise.
In relation to odours, Mr. Kellaghan confirmed that the sandflats Walker Corporation plans to excavate are not currently smelly, but that there is an odour of hydrogen sulfide at Eastmarsh Lagoon, several minutes’ drive away from the proposed development site.
His modeling of risks associated with airborne dust had not taken account of the changed development methodology revealed by the Walker Corporation last week, including a new containment area of sediments to be dewatered. The new arrangements may present difficulties in minimizing dust emissions from the site.
— Save Ralphs Bay Inc. : www.SaveRalphsBay.org —
