LAST WEEK ABC local radio news carried the following story:

Zinifex to remove gas cloud above zinc works
The visible gas cloud coming from the Zinifex zinc works in Hobart could be gone by the end of next year.
The company will spend between $2 million and $3 million on new technologies to remove sulphur trioxide gas from the air.
The program is in addition to the $2 million the company is already spending to reduce heavy metal pollution into the Derwent.
The general manager of the smelter, Brett Fletcher, says although the emissions are within environmental licence limits, removing the plume will improve the company’s environmental performance.
“I think it’s about engaging and understanding the expectations of our stakeholders,” he said.
“I mean I guess regardless of what the actual environmental impact of the plume is, is that if it’s seen to be unsightly and an inconvenience or a loss of amenity to people, we take that very seriously.”

The strategic problems of foreshore development around the Derwent are now becoming obvious to many — particularly the mainstream media. As exposed on Tasmaniantimes in April (The other state of the Derwent), the Government’s agenda to flog off the public foreshore is premised by the need to ‘keep the lid on’ public knowledge of the environmental degradation which has been inflicted on the Derwent after years of Government complacency and corporate profit.

Immediately after the first Ralphs Bay rally and news coverage of the vexing problem of heavy metal pollution in the sediment, the Derwent Estuary Program (DEP) released a Derwent “clean-up” plan. After 88 years of accumulated heavy metal pollution in the Derwent and State Government’s endeavours to ignore and screen this fact, it’s only now that a plan is put forward to seemingly address the problem! It is clear that the Governments spin machine has been in overdrive trying to redirect the media away from the nasty facts about the River.

The Government’s ‘status-quo’ plan

Conventional wisdom is that if no serious attempt is to be made in addressing heavy metal accumulated in river sediments, then the next best thing (and cheapest option) is to leave the sediments undisturbed. Whilst the sediments remain in an anoxic environment, the heavy metals will remain entrapped within the silt matrix. Human disturbances to the sediment (dredging, pile driving, channel deepening etc) will without doubt remobilise the sediments and release the metals into the estuarine environment. However, that’s hardly a “clean-up” plan. Indeed the many years of accumulated metals will simply remain in situ where they can become part of the food chain via filter-feeding benthic shellfish, fish, sea birds and even marine mammals.

Unless developers for proposals such as at Ralphs Bay have invented a radical new method of emplacing substantial foundations, constructing island earth works by a process of osmosis, it is not clear how any development will not disturb these sediments. Any such proposal which may result is significant sediment disturbance should also include a plan to remediate the contaminated sediments. In the absence of this remediation, the Government/DEP “clean-up” plan appears to represent a “do nothing” plan which has been dressed-up as an “action’” plan — very Orwellian!

In the case of Ralphs Bay, heavy metal concentrations in the sediments tend to greatest at the mouth of the bay. Although these decrease further into the bay, the concentrations in the sediments of the northern and southern embayments near Laurderdale are still at concerning levels. Interestingly the ability of the Derwent to naturally flush heavy metals from Ralphs Bay is somewhat dependent on the water depths, currents and prevailing summer tides (Jones et al., 2003). Hence any plans to dredge and deepen the bay must consider the impact of these activities on the Bay’s natural remediation processes.

In a striking contrast the Victorian Government succumbed to community pressure in late 2005 when the residents of Williamstown lobbied against dredging plans to widen and deepen the Port Phillip shipping channel. Residents successfully argued that heavy metals contained in the port sediments would have an adverse effect on the environment if dredging was permitted. The Victorian Government called a cessation to any dredging plans pending the outcome of an independent environmental report (due after November 2006). Will the Tasmanian Government has the good sense to utilise the precautionary principle with regards to health and environment?

Heavy metals blowing in the wind

The more alarming aspect of the Government’s spin-doctoring on the announcement of the Derwent “clean-up” plan was the strategy to spend a few hundred thousand on reducing stormwater and industrial groundwater/run-off into the river. Whilst this is an admirable strategy to assist with water quality, what many people fail to realise is that heavy metal contamination of sediments (the main pollution problem in the Derwent) is generally unaffected by the water column. Much of the heavy metal in the Derwent sediments makes its way there via deposition of particulate matter (fine dust) emitted from industrial processes and vehicle exhausts. A study published in the Australian Journal of Earth Sciences notes that heavy metals commonly enter the Derwent in a solid form more-so than as dissolved elements (Jones et al 2003). The same study notes that: “pollutants have been added to the estuary during bulk handling at the refinery wharf by proximal atmospheric fallout from bulk handling … from stockpiles or stack emission and/or from groundwater discharge”. (The residents of Port Pirie, South Australia know all about that.) Given this information and despite the spin, the announced strategy is likely to have a minimal effect on the levels of heavy metal contamination in sediment.

The extent of the problem

Sedimentation rates in the Derwent are rather high (6mm per year) and the area of the estuary is about 198km2. Heavy metal sediment distribution maps show that about 80% of the estuary (from the mouth of Storm Bay to New Norfolk) has elevated concentrations of Lead, Cobalt, Zinc, Iron, Copper, Tin, Arsenic, Gold, Cadmium and Mercury. This means that since the commencement of smelting 88 years ago, the amount of heavy metal contaminated sediments deposited in the estuary will have an average depth of about 0.5 meter. Volumetrically as much as 78,400,000 cubic metres — weighing 203,840,000 tons — of contaminated sediments may have been deposited in the Derwent (including the Ralphs Bay area) since1918 — or volumetrically enough to fill about 70 MCGs to the top of the grandstand roof (excluding compaction coefficients). However not all of this sediment would warrant urgent remediation and the realistic amount of sediment that may be targeted for remediation would be a portion of this amount, but nonetheless, large.

Of course this sounds very daunting — and expensive to clean up. The common line presented by the Government confronted by this problem is that such any real clean up would be an onerous imposition on the public purse, may involve new taxes and there are hospitals, schools, law & order, race tracks, football teams to spend the money on. This old scare tactic of distracting the public with inflated costs for remediation is often an efficient way for the spin doctors to deflect public outrage regarding environmental degradation — but is it true?

What other governments have done

Whilst the clean-up of contaminated river sediments is a vexing problem, an entire remediation industry has evolved to tackle the problem. The massive US Corps of Army Engineers has a specialist centre, with innovative technologies, which both advises and provides world-wide contract services for the clean-up of contaminated sediments. The Corps is presently engaged by the US Environmental Protection Agency (USEPA) on a number of national projects including the clean-up of the heavily contaminated sediments of the vast Great Lakes (Great Lakes Legacy Act).

The US Great Lakes cover a massive surface area with Lake Superior alone covering 53,350 km2 and holding about 95% of the US’s entire water capacity. Parts of the lakes are heavily contaminated (affecting both water and sediment quality) following decades of industrial and mining pollution in both the USA and Canada. In 2002, the US EPA estimated that the there was about 76.5 million cubic yards of highly contaminated sediment in the lakes to clean up, at an estimated cost of US$1.6-$4.4 billion. Much of this remediation work has now been undertaken. It is interesting to note that despite the fact that Lake Superior covers 269 times the area of the Derwent Estuary, the estimated volume of contaminated heavy metal sediments targeted for remediation (in all the North American Great Lakes) is similar in volume to the probable total contaminated sediments in the Derwent Estuary!

Who pays?

In 1980 the US Senate passed legislation to enact the Environmental Protection Agency (EPA) Superfund. The US EPA Superfund provides a cash reservoir by which dire environmental problems in the US are addressed in the long term. A list of national priority sites is assessed and updated annually by the EPA and remediation activities are based on the targeting of this list using Superfund monies. The Superfund budget is now $1.6 US billion per year — but it may surprise many readers to know that the cash doesn’t all come from the public purse. Indeed the US EPA Superfund policy is that where environmental damage can be traced to a known polluter (chemical company, mine etc), then the cleanup bill is made payable to that polluter — and is legally enforced! It can be done.

Another urban myth goes down the river

In summary, when we look with a critical eye outside the small fiefdom of Tasmania, we see that the rest of the world has stopped using the dinosaur arguments against environmental responsibility that we commonly hear from our governments. Not only have they stopped using the arguments but they are actively cleaning-up the mess produced by years of abrogated government responsibility and cosy industrial friendships. Mechanisms exists for both the technical clean-up of the Derwent and for the payment of this service. Based on the US example, the amount of money that the State Government is more than happy to hand-over to British company National Grid International to rent the Basslink cable (over $92 million p.a. for the next 25 years) would be more than enough to substantially fix the Derwent problem — and what’s more — importantly it doesn’t necessarily have to all come from the public purse (as demonstrated by the US EPA Superfund). This is not an issue of blaming an individual, developers, company or single government. As a social issue with profound impact on all citizens, the legislative and policy reforms required for Superfund-style remediation processes in Australia, need to be driven by leadership at the highest levels — and should be demanded by all.