Why is dumping the Dredged Spoil on Land not a good idea!!

People are complaining about "dumping in the marine park" but do they realise what's being dumped?

It's dredge spoil which is just seabed material. It has to be tested for contaminants before being dumped at sea. 

What are the alternatives? -  Land dumping which could lead to acid sulfate soils. 

Dumping the Dredged Spoil from the Expansion at Abbot Point on land has been brought up time and time again from the anti coal activists.  One of the main reasons why it is not a good idea is because once the dredged material is exposed to oxygen it becomes Acid Sulfate!!  Let's explain exactly how this process works and why it is better to replace what comes from the ocean back to the ocean!!

What are acid sulfate soils?

Acid sulfate soil is the common name for soils that contain metal sulfides. In an undisturbed and waterlogged state, these soils may pose no or low risk. However, when disturbed or exposed to oxygen, acid sulfate soils undergo a chemical reaction known as oxidation. Oxidation produces sulfuric acid which has led to these soils being called acid sulfate soils.

How and where are acid sulfate soils formed?

Acid sulfate soils are formed by bacterial activity in waterlogged conditions when there is no or little available oxygen.

Naturally occurring bacteria convert sulfate (dissolved salt) from seawater, groundwater or surface water into sulfide (another type of compound that contains sulfur). This sulfide reacts with metals especially iron in the soil sediments or water column, to produce metal sulfides (the main components of acid sulfate soils). In order to convert the sulfate into sulfide, the bacteria also need a source of energy provided by organic material such as decaying vegetation.

Diagram Figure 2.1 from National Guidance for the Management of Acid Sulfate Soils in Inland Aquatic Ecosystems — Environment Protection and Heritage Council and Natural Resource Management Ministerial Council (2011)

Acid sulfate soils occur in inland and coastal environments.

Coastal

Supratidal iron-staining, Cairns QLD
Photo: B. Powell

Acid sulfate soils occur naturally around Australia's coastline. These soils were formed and deposited in areas that are, or once were, coastal environments.

Coastal acid sulfate soils are commonly found in mangrove forests, saltmarsh, floodplains, and salt- and freshwater wetlands.

Why are acid sulfate soils an issue?

Jarosite is a field indicator that iron sulfides in acid sulfate soils are oxidising and forming sulfuric acid
Photo: B. Powell

When acid sulfate soils are disturbed or exposed and react with oxygen, they produce sulfuric acid which may be accompanied by certain hazards. Metals may be released from sediments and become bioavailable in the environment, oxygen may be removed from the water column and gases such as hydrogen sulfide, sulfur dioxide and methane may be released.

What makes acid sulfate soils an issue?

The majority of Australia's population is concentrated along the coastline and there may be significant development pressure on this land. Urban development and other land use changes such as marinas, canal estates, underground pipes and swimming pools, may result in the disturbance or exposure of acid sulfate soils.

Dredging operations may disturb or expose metal sulfides with serious effects if dredging and dredge spoil disposal is not suitably managed.

What may be affected by acid sulfate soils?

 

Acid sulfate soils may affect the following key environmental values or uses:

• aquatic ecosystems
• primary industries
• recreation and aesthetics
• drinking water
• industrial water, and
• cultural and spiritual values

Source: Department of the Environment

So, is it best to replace what has naturally come from the ocean on land?? Or, back to where it originally came from?

 The technique that will be used for the dredging at Abbot Point will ensure that none of the dredged material will be exposed to oxygen.  It is sucked up from the seabed directly into the dredger where it is kept wet at all times and then released from the bottom of the dredger straight back into the ocean.  The majority of the spoil will sink straight back to the seabed. Back to an area of similar seabed floor.!!

It therefore is not wise to put it on land. Yes, it can be treated. But, that is timely, costly and a large area is needed to facilitate this. Most ports have not got the added area where this can take place!!  As the Caley Valley Wetlands are close by to the Abbot Point Terminal, it is also wise to keep the spoil away from such a significantly beautiful area.

 

Extending the Trestles??

 

Why extending the trestles at Abbot Point is not viable!!

There has been a lot of talk all over the media and internet saying that the trestles could have been extended instead of returning dredged material to the marine environment.

Extended trestles were one of several options considered to achieve a balance between environment, social, safety and financial viability. There are a number of significant constraints associated with trestle extension. These include a higher exposure to extreme weather events, difficulties operating a port in the Marine Park as opposed to within port limits, additional operating and maintenance costs, and navigational safety concerns.

A number of onshore, inshore and offshore options were considered but, relocation to a deeper offshore relocation area remained the best option.

As quoted by North Queensland Bulk Ports:

Source:  North Queensland Bulk Ports

              North Queensland Bulk Ports Q & A

              GBRMPA Q&A

 

 

Working Side by Side with Nature!!

Working Side by Side with Nature

The coal terminal at Abbot Point came into operation on the 25th February 1984.  Since then it has co-existed right next door to the Caley Valley wetlands.  This proves that industry can work side by side with nature with no environmental impacts.  The wetlands are just as beautiful today as they were before the port was built.

The wetlands have also been used as an emotional tool against the expansion at Abbot Point.  As usual, no scientific evidence to back up the claims by the environmental activists that any harm has ever come to the wetlands.

Working side by side with Nature!!

 

Is the Sediment Toxic Sludge??

All over the internet and even in news reports on radio and television, the Green Groups have called the sediment that will be dredged - SLUDGE! It is in fact sand , silt and clay!!

More scaremongering and misinformation to gain support for their cause!!

Here are the FACTS on the area to be dredged:

Where is the approved disposal site?

The approved dredge disposal site is located approximately 25 km east-north-east of the Port of Abbot Point.

It falls within a General Use Zone of the Marine Park — under the Zoning Plan for the Marine Park, dredge disposal is considered to be a permissible activity within such a zone, however it requires a permit.

What is the disposal site made up of?

The 400 hectare (four square kilometres) disposal site is 39–44 metres deep and is situated in a large band of sand, silt and clay. Based on studies by North Queensland Bulk Ports, there is no hard coral or seagrass within the disposal site.

 

Is the disposal material toxic?

The dredge material to be disposed of in the Marine Park is a mixture of sand, slit and clay.

All material destined for ocean relocation is tested by accredited laboratories and has to comply with strict requirements under the National Assessment Guidelines for Dredging.

Analysis of sediment from Abbot Bay has not identified any contaminants of concern at levels that would impact on the marine environment. As a result, it is deemed to be suitable for ocean disposal.

 

Under these and other strict environmental standards, dredging has been conducted successfully for decades with minimal impact on the marine environment.

Source: Great Barrier Reef Marine Park Authority

So. is it sludge?? No!!  It is sand , silt and clay!!

Is it toxic?? No!! It has been tested and found to be non toxic!!

 

Dredging Myths and Facts

Dredging Fact

‘Once again the anti-resources activists have been caught out in their latest scaremongering campaign that features re-runs of Bob Irwin’s Fight for the Reef TV advertisements,’ Mr Roche said.

‘All of the false claims put forward in the ad – which we have seen before – are wrong, including the number of coal ships that will export from the ports and claims of fast-tracking mega industrial ports.

‘The WWF ads have Mr Irwin claiming that 7,000 coal ships will be 'crossing the reef'.

 ‘No coal ships 'cross the reef' - they in fact travel through designated naturally occurring shipping channels.

‘The official forecast from the Australian Maritime Safety Authority is that by 2020 some 2,450 coal ships will be using the coal ports in the reef zone.


Source: Queensland Resources Council



Keeping the Reef and Ships Safe 

All ships traveling through the designated naturally occurring shipping channels are monitored by REEFVTS

 

Australia leads the world in shipping management, demonstrated by the International Maritime Organisation’s adoption of Australia’s mandatory ship reporting system in 1996.

Since then we have boosted navigation services through automated position reporting, an automatic ship identification system and decision-support tools mandated for use along the entire length of the Great Barrier Reef (GBR).

The system is called REEFVTS and operated 24/7 from Townsville. Despite a substantial increase in ship movements since 1996, groundings have reduced from one per year to just a single incident in the 10 years since its introduction.

The increased coverage of the system in the southern GBR means that all shipping activity is now monitored, greatly reducing the likelihood of an industrial shipping incident in the future.

Source: Queensland Resources Council

 Designated Shipping Channel to Abbot Point