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Desalination, perhaps; dumping brine in Spencer Gulf, no

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Alternatives
Future expansion
Giant cuttlefish
Conflict of interest?
Correspondence with BHP Billiton
Development at any cost?
Notes re desal plant
Links
Index
 

BHP Billiton's proposed desalination plant in northern Spencer Gulf will increase the salinity of the already hypersaline Gulf. This will compound the increasing salinity of the Gulf already happening due to global warming.

There is a perfectly viable alternative to the proposed Port Bonython site, but BHP is unwilling to pay the marginal extra cost involved.

Contact: email me at daveclarkecb@yahoo.com
Created 2006/12/22, modified 2010/02/09
Also see SA's water supply.

Introduction


 

Compounding problem

The BHP desalination plant is not the only cause for increasing salinity in Spencer Gulf; it is one of a number of factors...
  • Upper Spencer Gulf is naturally hypersaline because it is in a hot dry area where evaporation rates are high, where there is negligible fresh water runoff from the land, and that has limited mixing with the ocean;
  • The temperatures are rising (climate change) with consequent increases in evaporation rates;
  • The Port Augusta (coal-fired) power station dumps warm water into the upper Gulf, further increasing evaporation and therefore salinity;
  • If the BHP desalinator is allowed then companies setting up other mines in northern SA will also want to build their own desalinators;
  • There is persistent talk of a nuclear power station near Port Augusta; this would also heat the upper Gulf and further increase evaporation.

Annual figures

These annual figures are based on 320ML/day being taken from the Gulf.

The plant will take 117GL of sea water each year and convert it into 44GL of fresh water, which would be removed from the Gulf, and 73GL of brine containing 5 million tonnes of salt, which would be put back into the gulf (Calculations).

BHP's environmental record

BHP is responsible for the infamous Ok Tedi mine in Papua New Guinea. Wikipedia calls this "one of the worst human induced environmental disasters in the world". BHP now faces a $US4 billion dollar lawsuit on behalf of 13 000 villagers over environmental damage due to the mismanagement of this mine.
The figures have not yet been settled, but BHP Billiton's proposal for their own needs was for a desalination plant near Port Bonython that will take 320 megalitres (ML) of sea water from Spencer Gulf each day, separate this into 120 ML of fresh water and 200 ML of brine. The fresh water will be piped to Roxby Downs/Olympic Dam, the brine will go back into the Gulf.

The state government did propose to increase the size of the plant so that it can take water to supply the north and west of the state, but I believe that this idea has been dropped in favour of a separate desalination plant somewhere on the west coast of Eyre Peninsula.

As the brine discharged from the desalination plant will be significantly heavier than 'normal' Gulf water it will go to the bottom. (One ML of fresh water weighs a thousand tonnes, one ML of sea water weighs about 1030 tonnes, one ML of this brine would weigh about 1050 tonnes.) The expected power consumption (for the BHP Billiton proposal) is 30MW; it should be sustainably generated.

Chemicals used in the water pretreatment and in the reverse osmosis process itself can also be problematic when they are released, with the brine stream, back into the sea. Coaguants like ferric- or aluminium-chloride can be used to improve the initial filtration process and both alkaline and acidic solutions are used in the RO plants to remove silt deposits, biofilms, metal oxides and scales. However, I believe that reverse-osmosis seawater desalination plants can be designed and operated without needing such undesirable chemicals, or at least without releasing them into the waste stream. More can be read on the Clean Ocean Internet site, the full URL for what is probably the most relevant page is http://www.cleanocean.org/index_general.asp?menuid=040.090.010.

The upper Spencer Gulf already becomes hypersaline in summer due to the high evaporation rates and poor mixing with the open ocean. The addition of 200 000 tonnes of brine to the upper Gulf each day, I believe, would have to have significant adverse effects on the health of the Gulf. The additional salt load to the Gulf would be similar to increasing the area of water available for evaporation by 22km2 without the increased tidal flushing that an extra 22km2 would bring (Calculations).

The brine will be released into water greater than 20m deep, too deep for seagrass to grow (see Correspondence with BHP Billiton), but it will go to the bottom where it will be swept backward and forward by the tides, gradually mixing with the Gulf water. By increasing even further the salinity in the Gulf, it must place more stress on the plants, fish, prawns, cuttlefish and squid. The Spencer Gulf prawn industry alone is worth $20 million dollars per year. Also the spawning ground of the Giant Cuttlefish is important environmentally and as a growing tourist industry. These species, and others, should not be put at risk.

The SA state government and the federal Rudd opposition have each promised $160 million dollars for the construction of this desalination plant. One wonders why they seem to have been willing to overlook the risk to Spencer Gulf, considering that there is a viable and preferable alternative site available.

Climate change is already increasing the salinity of Spencer Gulf. Research has confirmed that increasing temperatures due to climate change has significantly increased surface salinities in the world's tropical oceans. (See OLPA. The research was done by Ruth Curry of the Woods Hole Oceanographic Institution.) Temperatures are increasing in South Australia, so it follows that salinities will also be increasing in Spencer Gulf.

The only way that I can see that this desalination plant should be allowed to happen is if the brine is kept out of the Gulf. There are several ways of doing this. It could be pumped to evaporation basins, the salt harvested and sold. The evaporation basins, which would need to be something like 35 square kilometres in size, should be located in an existing salt lake so that no land needs to be degraded and to minimise vegetation clearing. The most conveniently placed such site could be the southern end of Lake Torrens, seventy kilometres north of Port Augusta and close to where any pipeline from the Gulf to Olympic Dam mine will have to go.

The proceeds from the sale of the salt would go some way toward covering the additional cost.






Alternatives

An alternative location for the BHP desalination plant

Disposing of a large quantity of brine from a large desalination plant could be done with much less environmental risk if the facility was located on the west coast of Eyre Peninsula rather than in upper Spencer Gulf. There is much more movement of the ocean on the west coast, the brine could more easily be dispersed. Wherever the desalinator, the brine would go straight to the lowest point; in the Gulf this would result in a layer that would wash backward and forward with the tides, on the west coast it would flow down the slope of the continental shelf, the continental slope, onto the abyssal plain; where it would probably not do no harm.

Streaky Bay is only about 70km further from Olympic Dam than is Port Bonython; 340km as against 270km for Port Bonython. The additional cost of a longer pipeline would be offset to some extent by the lower salinity of sea water at Streaky Bay compared to that at Port Bonython. (The lower the salinity of the feed water the lower the cost per kilolitre of fresh water produced.)

Alternatives for South Australia

In order to provide a more assured supply for the portion of the water that goes into the SA supply it would seem better to have several smaller desalination plants spread around the state rather than placing too much reliance on one.

Other prospective sites would be Ceduna, Port Lincoln and Adelaide. This is discussed further in SA Water.

Economies of scale apply to desalination plants, but information I have received indicates that economies of scale flatten out for reverse osmosis plants when they reach about a seventh of the size of the proposed BHP-Billiton plant; that is at about 6GL/yr.

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Giant cuttlefish mating
Mating giant cuttlefish
Photo - credit Mick Hines


Giant cuttlefish

The False Bay area (in which this desalination plant is to be built) is one of the main habitats in the world of the Australian Giant Cuttlefish (Sepia apama). It is also their best known spawning ground. The desalination plant should not go ahead if there is any chance that this habitat and spawning ground will be under any risk. Read more about the giant cuttlefish.


The piece below was extracted from the ABC news service.

Adelaide University Associate Professor [and marine biologist] Bronwyn Gillanders says cuttlefish only breed once in their lifetime. She says if increased salt levels caused by the proposed plant negatively affect the cuttlefish reproductive process, the entire population could be devastated.

"I'm particularly concerned about them at that Point Lowly, Port Bonython area because that's where they aggregate," she said.

"We do know that they breed in other places but nowhere near the hundreds and thousands that they do at Point Lowly."

Ms Gillanders says unlike fish, increased salt levels may be disastrous for cuttlefish.

"Squids and cuttlefish are generally short-lived," she said.

"They live a year. They breed only once. So if you damage the eggs or affect their reproductive ability then potentially that will have devastating consequences for the population."






Future expansion

The head of Spencer Gulf is the closest point of the sea to about 15% of the dry Australian inland. There will be more mines or other developments wanting to get desalinated water from the Gulf; for example any mine constructed to take advantage of the newly discovered uranium deposit near Beverley in the northern Flinders Ranges.

Already the South Australian government has stated that it wants to take a third of the water from the proposed BHP Billiton desalination plant for northern SA and the Eyre Peninsula.

If this development is allowed to dump its brine in the Gulf it will be only the first stage.

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Conflict of interest?

It has been proposed that the SA government and a future Labor federal government will each provide $160m for building the desalination plant. It has also been proposed that a third of the desalinated water from the plant will be used to augment the supply to northern and western SA.

What happens if the desalination plant is unable, for whatever reason, to run at full capacity for some period of time. Will the existing pipelines from the Murray be sufficient to make up the loss, and if not, who will have to suffer reduced water supplies? Will BHP Billiton supply Olympic Dam and the water consumers of northern SA and Eyre Peninsula go without? Would this be fair considering that the tax payers of Australia will have put so much money into the development?

Oil spills have occurred from Port Bonython, which is very close to the proposed desalination plant. An oil spill could seriously damage the desalinator.

Wouldn't several smaller quite independent desalination plants in different places be a better option for these reasons?

I would like to thank Eric Barro for bringing up this point.

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Correspondence with BHP Billiton

I contacted BHP Billiton several days before writing this page and expressed the concerns that I have outlined on this page. They replied around mid January. Their reply was non-committal and very general. It made no specific remarks on my concerns.





Correspondence with Richard Yeeles, BHP Billiton

I asked the people at Olympic Dam why they did not desalinate and reuse the Great Artesian Basin water rather than desalinating Spencer Gulf water and piping it all the way from Port Bonython (a distance of nearly 300km). I received the following reply:

Thursday, 1 March, 2007 1:18:59 PM
Subject: Letter to BHP Billiton

David

You suggest re-cycling of water used at Olympic Dam from the GAB rather than desalination.

To the extent it is able to do so, Olympic Dam does re-cycle water used in its operations. However, there is a limit to how much re-cycling can be achieved.

The cost of water to Olympic Dam is high. Olympic Dam has paid the full cost of the GAB infrastructure necessary to supply water. This is now in excess of $100 million. Olympic Dam also pays all operational and maintenance costs. As a result, the cost of water to Olympic Dam exceeds that available at locations closer to metropolitan and regional cities and towns.

Owing to the high cost of supply, the processing facilities at Olympic Dam were designed and built, and are being operated to be efficient in the use of water. However, the continuous re-use of process water results in the build up of salts (particularly chlorides) and other contaminants, which originate either from the initial water source or from the ore or process chemicals used. Eventually, the concentrations of some salts and other contaminants become so high that they have detrimental effects on process efficiency. BHP Billiton is continuing to research and develop methods to reduce consumption and to encourage water conservation.

In relation to the proposed desalination plant, this is still subject to a pre-feasibility study. In this work, intensive research is being undertaken to assess the impact of brine disposal to the gulf.

Development of desalination plants typically focus on the following issues -
- brine discharge and the potential impaacts on the marine environment
- energy use and greenhouse impacts
- community and economic impacts

In preparing an Environmental Impact Statement, BHP Billiton is continuing to undertake detailed ecotoxicity testing of marine species in the gulf (Yellow Tail Kingfish, Western King Prawn, Cuttlefish, etc) and has gathered the most comprehensive data ever assembled on tidal flow, plume dispersion modelling and site location. The results of this work will be reported in the Environmental Impact Statement to be released later this year.

I trust this information is of assistance.

Richard Yeeles
Base Metals Australia


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As this did not really answer my original question (perhaps I was unclear) I wrote again; as below:
1 March 2007
Dear Richard;

What I was really wondering is that if desalination of Spencer Gulf water plus piping all the way from Port Bonython to Olympic Dam is economically viable, why is not desalination of process water at Olympic Dam? You mention build up of chloride; I know that chloride is readily removed by reverse osmosis (while some other ions such as boron are not). Does the chloride get to levels that are too high for economic desalination? Do you do any desalination for the mine at OD?

David Clarke

A reply was received on 2007/04/12 (apparently my email of 1st March did not get to Richard):

The acid waste water stream at Olympic Dam has low pH. The cost of neutralisation is prohibitive and RO is not possible before neutralisation.

In addition, there are other contaminants in solution after the leaching process that will not be rejected, such as fluorine and boron - these would quickly destroy an RO membrane and make the process uneconomic.

Minewater is not desalinated on site but is shandied back into the process. The waters are low in chlorides compared to seawater desalination so this is not the issue - it is a combination of a low pH and contaminants in solution that prohibit recovery of acid water by desalination. At the proposed expanded capacity of the operation, we will reuse as much of this acid water back in the process as possible, limited only by contaminant build up.

Richard Yeeles

As Richard mentioned that ecotoxicity testing was done for marine species including Yellow Tail Kingfish, Western King Prawn, Cuttlefish, but did not mention whether any testing was done on plants at the bottom of the food chain, I asked him whether BHP Billiton had done such testing.

His reply (received 2007/04/13) is below:

Impacts of the brine discharge on the general Upper Spencer Gulf ecosystem have been assessed via ecotoxicology studies using a technique called Whole of Effluent Toxicity (WET) testing. During these studies various concentrations of simulated brine were tested against seven indicator organisms from a range of taxa that included two species of marine algae. The algae tested were the microalgae Nitzschia closterium and the macroalga Hormosira banksii. The technique is used to derive a species protection value or "safe" dilution of effluent to protect 99% of marine flora and fauna species. Hydrodynamic modelling of the dispersion of the brine plume have indicated the "safe" dilution of the brine would generally only be exceeded within hundreds of metres of the outfall, and up to 1.5 km for a short time during dodge tides.

The marine plant species of greatest interest is the seagrass Posidonia spp., which covers extensive areas Upper Spencer Gulf, but only to a depth of about 10 metres. There is no seagrass in the vicinity of the brine outfall as the water is too deep (> 20 m). The nearest extensive seagrass communities occur in False Bay and Fitzgerald Bay, 5-10 km from the outfall. Furthermore, Posidonia spp. is adapted to highly saline conditions - extensive communities occur near Port Augusta where salinities reach 47-48 ppt in summer. It's therefore extremely unlikely that the discharge of brine would have adverse effects on seagrass communities in Upper Spencer Gulf.

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Government wants development at any cost?

On 21 Feb. 2007 the Port Lincoln Times published the paragraph below:
Mr Foley said the Government's information was there would be "no impact on any of the fishing grounds" but they would continue to monitor the situation closely throughout the Environmental Impact Study process, which is expected to take 12 to 18 months.
The pre-feasibility study has not even been done yet. See correspondence with Richard Yeeles, BHP Billiton, elsewhere on this page. How can Kevin Foley make a statement like that?




Update 2007-04-02

It was announced on ABC radio today that a pilot plant is to be built. This is apparently to be constructed immediately, with no requirement for any environmental impact statement.

It has been claimed that no site has definitely been chosen. Yet the pilot plant is to test pre-filtration equipment that is specific to the Port Bonython site!

Kevin Rudd has committed a future federal Labor Government to $160 million toward this desalination plant. There was no mention that I heard of any environmental conditions placed on the money.

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Notes re desal plant at Port Bonythan

The density of fresh water is about 1000kg/m3, that of ocean water is about 1027kg/m3.

Natural salt content at the head of the Gulf can reach 4.8% in summer, CSIRO. Ocean water is typically around 3.5% salt, Wikipedia. From these three figures we can calculate that the density of 4.8% Gulf water would be about 1037kg/m3.

The Olympic Dam desalination proposal includes the release of water at 6.5% salt into the Gulf near Port Bonython. The density of this water would be around 1050kg/m3.

Pan evaporation at Adelaide is about 1600mm/yr. It would be considerably higher in upper Spencer Gulf; for the calculation of the additional evaporative area that the adding of the brine from the proposed desalination plant would equal, I have assumed 2000mm/yr.

Calculations

The proposal includes the return of around 200ML of this brine to the Gulf each day.
200ML of sea water at 3.7% (1029kg/m3) salt would weigh (1029 x 200 000 / 1000) about 205 800 tonnes.
200ML of brine at 6.5% salt would weigh (1050 x 200 000 / 1000) 210 000 tonnes, or 4200 tonnes more than sea water at 3.7% salt content.
200ML/day = 73GL/year (200 x 365 = 73 000).
73GL of brine at 6.5% salt (by weight) contains 5 million tonnes of salt (73GL of fresh water weighs 73 000 000 tonnes; 73GL of 6.5% brine weighs 76 650 000 tonnes; 6.5% of 76 650 000 is 4 980 000)

The desalination plant will take about 44GL of water from the Gulf each year. At 2m evaporation per year, this is equivalent to the evaporation from an additional 22 square kilometres of exposed water, without the additional tidal flushing that 22km2 would bring. (44GL = 44 000 000m3
Evaporation is 2m/yr, so 44 000 000m3/2m gives 22 000 000m2 = 22km2 of evaporative area.)






Links

Solar power combined with desalination proposal at Whyalla. This was to use technology developed by Australian National University (ANU) engineering professor Stephen Kaneff and it's viability was the subject of a KPMG study in 1999. However, it seems to have stalled for lack of government support. Green Left online 2001/06/06.

A solar powered desalination plant at Port Augusta (northern end of Spencer Gulf) has been proposed by Acquasol. This proposition is preferable environmentally to the BHP plant (this should be greenhouse neutral and will not dump brine in the Gulf), Michael J. Fielden, Managing Director of Acquasol Pty Limited informed me by email that "... our company is listing in July, and construction on our project will commence early next year (2008)." (He also promised me more information on the proposal. I didn't ever receive this.) On 2009/03/18 Acquasol's Net page was still non-commital about whether construction was underway.

A page on the BHP proposal is at Olympic Dam EIS Project.

"A Water Supply for Regional South Australia: Reducing Reliance on the River Murray Feasibility Assessment Report", a 2.5MB pdf file, can be downloaded from TheLivingMurray site. (The full URL for the report is
http://www.thelivingmurray.mdbc.gov.au/__data/page/195/ SA_desalination_Feasibility_Final_Report_for_web.PDF).

Renfrey Clarke discusses the proposal on Green Left On Line.

The US Department of the Interior - Water Treatment Engineering and Research Group has a comprehensive, if difficult to navigate, 3.6MB document titled Desalting Handbook for Planners at the full URL of http://www.usbr.gov/pmts/water/publications/reportpdfs/report072.pdf

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Index

On this page...
Alternatives
Conflict of interest?
Correspondence with BHP Billiton
Correspondence with Richard Yeeles, BHP Billiton
Development at any cost?
Future expansion
Giant cuttlefish
Introduction
Links
Notes re desal plant
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Update 2007-04-02