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Appendix A - Northern Territory Government Comments on The Draft Environmental Impact Statement

The following are comments and other matters raised by NT Government Agencies following a review of the draft Environmental Impact Statement (EIS). All these are matters which the proponent must address in the supplement to the draft EIS. As a general comment the EIS should refer to and continue or modify commitments made in the previous Preliminary Environmental Report (PER) and current Environmental Management Plan (EMP).

1. Ore Characterisation and Tailings Management

Analysis of the ore indicates the presence of sulfides and arsenic. Hence:

  • There is no guarantee that the pit water and/or dewatering will not become acid at some time in the future when contacted by sulfide ore. The company should therefore design a contingency plan for treatment, such as a wetland filter and obtaining a discharge licence as acid water may have to be disposed of.
  • It is likely that the tailings and tailings water will become acid. The company should consider the effect of this in their requirements for make-up water, tailings dam water management and rehabilitation.

The proposed ore treatment process is new to Australia and details of the chemistry of tailings from this process are required. In particular, details of cyanide and kerosene life cycles and consequent tailings management are required, as well as the chemistry of tailings in relation to ore chemistry.

Has sterilisation taken place at the interim pond site? Data will be required to support this statement.

2. Waste Rock Characterisation and Management

The frequency of sampling for waste characterisation is inadequate. The results quoted in the text and Appendix C are questionable and do not correspond with figures given in the Tables in that Appendix. It is also not possible to relate test results to actual sampling locations.

Data used for NAPP is questionable:

Reported: Dolly Pot: -76 to 18kg H 2 SO 4 /tonne
Actual: Ore: -76 to 100

Waste: -76 to 27
Reported: Beef Bucket: 15 - 34 kg H 2 SO 4 /tonne
Actual: Ore: 25 to 400

Waste: 15 to 34

It appears that there is considerable risk of sulfides being dumped alongside oxide waste. In any case, the dump will contain potentially acid forming (PAF) primary waste. Detailed rock sampling will be essential.

Therefore, in addition to the selective dumping proposed, all precautions should be taken to prevent contact of PAF waste with air and water, such as diversion of upstream run-on water around the dump, compaction of the base and outer shell of the dump, the use of paddock dumping etc.

3. Water Management

The ore and waste rock characterisation has major implications for site water management. The water management system should clearly state site water management objectives and how they will be achieved. Clean water should be diverted around the site wherever possible. Expected volumes and flows of pit water, tailings water and plant runoff should be detailed, in relation to the capacity for their storage/treatment. The expected "considerable increase in water usage" (p 14) should be quantified. Both a water budget, and a map showing areas of clean water runoff, potentially contaminated and contaminated waters, disposal sites and routes are suggested. A map showing existing and proposed monitoring sites is required.

Plant runoff management should consider the likely contaminants this water will come into contact with.

It should be noted that Annie Dam (p 26) is a pastoral dam. It is not an engineered structure for containment water which may be of unacceptable quality for release.

The significance of waste water spills depend on both quantity and quality, not only quantity. How was the volume of 0.5 ML (p 49) derived as smaller spills may well be significant?

4. Rehabilitation

In addition to the proposed final land use, a description of final landforms should be provided, with details of how this will be achieved, final gradient of batters and the plant species to be used. In particular, the management of potentially poor quality runoff after decommissioning needs to be addressed as does the monitoring of rehabilitation trials and the rehabilitation in general.

5. Weeds Management

The draft EIS gives scant attention to the Northern Territory Weeds Management Strategy 1996-2005 released by the NT Government in 1996. It is also inadequate in describing the species that occur on site as is the reliance on "harsh environmental conditions" to stop weeds. The current situation does not reduce the potential threats from weeds in any form of development that involves disturbance to land.

Details are required on:

  • how a policy of isolation and containment will be practised, enforced and monitored;
  • the hygiene of all vehicles, machinery etc. moving onto and from the site at all stages of the project - from initial surveys to rehabilitation; and
  • the species and methods that will be used in rehabilitation - weed species must be excluded (from seed supplies for example) and consideration should be given to matters like fire regimes on reclaimed areas.

The Weeds Branch of the Department of Primary Industry and Fisheries is able to advise on weeds and weeds management and should be consulted on these matters.

6. Mosquito Monitoring and Control

The baseline adult mosquito monitoring program will need to be reinstated due to the major changes at the mine such as the wetland filters, tailings dam and workers accommodation and the incompleteness of the original monitoring data. Baseline mosquito monitoring sites will need to be reviewed in consultation with Territory Health Services (THS) to accommodate these changes.

Regulatory monitoring was completed in August 1996 (p 38) but was deficient due to gaps in the data. While it is acknowledged that the majority of the mosquito population have previously been the result of dispersal from breeding sites in nearby swampland and flood plains it is stressed that this observation was completed before the installation of any wetland filters. These filters can be expected to elevate mosquito numbers and to create perennial breeding sites in an area where there was previously probably only wet season breeding.

Wetland filters will become prolific breeding sites of pest mosquito species and potential disease vector species if there is not adequate consideration to design, construction and management of mosquitos and to reed growth. In the absence of a suitable alternative to wetland filters, the filters should be designed to enable an annual reduction in the build up of dead vegetation in the filters. Annual maintenance is necessary to minimise the potential for mosquito breeding in dead and water logged vegetation. Native fish is the major component in controlling mosquitoes in wetland filters but their presence do not remove the need for annual maintenance of vegetation in the filters.

It will be necessary to monitor for mosquito larvae and the presence of aquatic predators in the filters to determine the timing for any mosquito management operations.

It should be noted that the "brown house mosquito" was detected on the site. Existing and the additional septic tanks to be installed on the site should conform to THS standards and be inspected on an annual basis to prevent the introduction of new or exotic mosquito species to the site.

The Medical Entomology Branch of THS should be consulted in the matters of mosquito monitoring and control.


Specific Comments

p 5 1.6 Item 3. What is meant by "...suitable for covering with cover soil" and where will this soil come from? Item 11. This sentence does not make sense.
p 7 2.2 The document does not clearly explain the need for the phase 2 development. What are the new reserves and mining schedules? This section should state the proven and probable ore reserves.
p 8 2.3 What is the underlying tenure of the land as post Wik High Court decision could be a major issue, in particular, as there may be a tailings dam on adjoining land?
p 11 3.1 Error in latitude and longitude. Eg reads 131029'S should be 131029 S. Table 1 "Surface Water Containment" needs definition.
p 12 3.3.3 A timetable of waste rock production showing availability of waste rock for tailings dam construction and future lifts, waste rock dump and tailings dam capping is required.
p 15 3.4.1 Plant runoff pond, silt traps and biological filter should be shown on a map and discussed in the water management section.
p 15 3.3.4 More information is required on the use of kerosene. Is it only required as an initial dose or to be continually added? How will the minimum addition of kerosene be managed to ensure "...no insoluble or unattached kerosene is allowed to develop....? What is the fate of the kerosene?
p 17 3.4.8 More details of cyanide recovery are required. What will be the concentration of cyanide in the tailings?
p 18 3.5.1 What is the total volume of tailings generated by the project? Options for tailings storage in years 4 and 5 should be discussed.
p 18 3.5.2 The use of site 6 or site 2 should be clarified. This section is very confused.
p 18 3.5.3 What is the significance of 1:100, 1 hr, 12 hr, 72 hr and 2 months events? How was the figure of 3 m lifts derived? Design principles and quality control should be specified. It is recommended that tailings dam design (including storage capacity) and construction be certified by a suitably qualified engineer.
p 20 3.5.4 Where is the tailings dam spillway located and where does it flow to? If the tailings dam were to overflow, how would this be managed? What downstream water quality would be achieved?
p 20 3.5.6 Will the tailings be thickened before disposal?
p 21 3.6.1.2 What are "the appropriate measures that will be undertaken to remove all contaminants"?
p 26 3.6.4 Other wetland filters are proposed throughout the document. Their location and design should be discussed in terms of the quality and volume of water they will be required to treat.
p 29 3.8.4 The storage location of hazardous substances should be shown on a map. Will the current compound be large enough to handle the increase in reagents? Will it be moved or enlarged? Water management in regard to storage and usage of hazardous substances should be discussed.
p 30 3.8.5 Details of diesel storage, volume and location will be required.
p 30 3.8.6 The Northern Territory Health Department should be Territory Health Services (see also p 38 & 42). Refuse disposal should be in accordance with the "Guidelines for the Siting, Design and Management of Solid Waste Disposal Sites in the Northern Territory" published by the Territory Health Services and the Department of Lands, Planning and Environment, in December 1995. Waste oils and solvents should be stored in approved containment areas. What are the flammable liquids and how will they be burnt?
p 31 3.8.9 What is the management implications for the access road because of additional heavy vehicle movements - safety/dust/road maintenance?
p 32 4.1.2 The proposed tailings dam 6 is in the Marrakai Catchment, not abutting this catchment.
p 33 4.1.2 The relevant flora, fauna and soils sections of Ref 5 could have been included as an appendix to make the document stand alone (see also p 37 4.1.6).
p 36 4.1.4 The document lacks data on existing surface water quality. Existing data should be collated. Potable water quality should include radionuclide concentrations.
p 37 4.1.5.1 Beneficial uses for the upper Mt Bundey Creek was declared in 1996.
p 38 4.1.7 What is the justifiable assumption that the noise survey conducted for the Jabiluka site is applicable to the Rustler's Roost mine site and how do the results apply to Rustler's Roost? What is the closest noise sensitive receptor? A noise survey of the site should be conducted.
p 40 4.2.2 A map showing sites 1.2.& 3 is required.
p 41 5.1.3 Non-discharging system conflicts with tailings dam design discussed earlier.
p 42 5.3.2 Where are the borrow pits and what will they be used for?
p 43 5.3.3 With the increase in wetland areas how will feral pigs be controlled? Are domestic pets allowed on site?
p 43 5.3.5 Consider the use of a firefighting tender or 4x4 trailer which can travel cross-country.
p 43 5.5 Will there be any positive socio-economic impacts such as more employment and wealth for the NT?
p 45 5.9 The licencing arrangements in place under the Water Act require the mine to report the Water Resources Division (WRD) of the Department of Lands, Planning and Environment prior to each release to Mt Bundey Creek and should be reflected in this section of the document.
p 47 5.9.3 Any significant spill from the water management system should be reported immediately (fax or phone) to the relevant authority (WRD for any spill into receiving water resources, DME on site). 10 days is too long to wait for a written report.
p 51 6.4 Responsibilities should be attributed to particular officers or positions.
p 51 6.5 Collection of "high quality water samples" is not the objective - rather representative water samples.
Appendix G No quantitative data is provided on the trial of the wetland filter trial which makes it difficult to assess the adequacy of the proposed filter systems.

There is no reference to the need for training and induction of staff and contractors in all aspects of the operation of the mine, in particular OH&S, environmental responsibilities and monitoring.

Appendix B - Proponent's Commitments

The following is a summary list of commitments expressed in the DEIS and this report.


Waste Rock Dump

  1. The waste rock dump will be non acid producing by encapsulating acid producing waste.
  2. Design will follow Consultant and NTDME recommendations and will blend with topography .
  3. It will be capped with suitable waste to seal out moisture and made suitable for covering with cover soil.
  4. Topsoil or selected waste rock will be used as growing medium in the rehabilitation program.


Processing Plant

  1. The area immediately around the new processing plant will be drained to a lined pond to collect spillage and process waters for recycling.
  2. The area external of the plant site will be bunded and drained to an dedicated silt trap and a biological filter shared with waste rock dump runoff.
  3. All process vessels will be contained within a concrete bunded area with sumps and dedicated slurry pumps.
  4. Resin will be regenerated and recycled.
  5. Kerosene will be managed so that insoluble or free kerosene is kept to a minimum.
  6. Cyanide will be recovered from the process waters prior to discharge.


Tailings Dam

  1. The tailings dam will be designed and constructed will meet extreme rainfall events.
  2. The tailings dam will be designed to be non discharging, but will have a contingency spillway.
  3. Cyanide levels will be maintained according to current best practise within the tailings dam.
  4. Under drainage and a toe drain will be installed to the tailings dam and any water collected will be recycled.
  5. Design and construction supervision will be by a qualified geotechnical engineer(s).
  6. Overland tailings pipes will be fitted with pressure devices and bunded, and a road built for inspection.
  7. Rehabilitation trials on the tailings dam will commence as soon as possible.


Water Management

  1. The process water circuit will be non releasing.
  2. All process water used in the plant will be collected in, and recycled from the tails dam.
  3. Annie Dam will be monitored and outflow will be treated if required.
  4. Excess pit water will only be released if it meets licence criteria.
  5. Waste dump underdrainage will be collected and drained via a settling pond / treatment sump, then through a series of wetland filters and sumps as determined by results of water monitoring.
  6. Runoff from roads will be directed to silt settling ponds and biological filters if required.
  7. Routine water monitoring will continue for the life of the project.
  8. Wetland filters will developed, managed and monitored as required.


General

  1. Leach pads will be decommissioned after the new RIL process commences, details will be in 1997-1998 EMP.
  2. Explosives and hazardous substances will be transported and stored to approved standards.
  3. Fuel storage will be built to Australian standards, containment bunds to provide 110% protection.
  4. Waste oils will be recycled.
  5. Solid refuse will be buried in a segregated elevated location in the waste rock dump and capped when finished.
  6. Camp amenities will be installed and operated to the Territory Health Services satisfaction.
  7. Local people will be employed and trained where possible.
  8. Earthmoving vehicles will be confined to the site.
  9. Feral animals will be discouraged.
  10. Bushfire management will continue.
  11. Conditions of the Aboriginal Areas Protection Authority and Heritage Unit will be maintained.
  12. A study on the impacts of kerosene to the environment will be supported following plant commissioning.
  13. The DPIF recommended weed management strategy will be complied with where practical.


Monitoring

  1. Water monitoring will be conducted in accordance with licence conditions and commitments.
  2. Regular monitoring will include pit, tails dam and any waters that could potentially by discharged.
  3. Mine waste characterisation will be conducted for acid rock drainage potential.
  4. Quality control procedures for monitoring will be detailed and documented in the Environmental Management Plan.
  5. Bacteriological monitoring of drinking water continue and radionuclide testing commenced.
  6. A mosquito monitoring and control programme will be continued in liaison with the Agricultural Branch of the NT Department of Primary Industry and Fisheries.
  7. Monitoring of rainfall, evaporation and temperature will be reported to the Meteorological Bureau.
  8. Reports will be through Annual Environmental Report and Environmental Management Plan.


Emergency Response Plan

  1. An Emergency Response plan has been drafted and will be implemented, reports will be made in accordance with the plan and legislative requirements.
  2. Contracts for transport will not be let without contingency plans being reviewed and approved.


Rehabilitation

  1. Rehabilitation will be undertaken as soon as possible and then progressively on the waste rock dumps and the tails dam.
  2. Rehabilitation of exposed peripheral areas will be done to minimise dust and erosion.
  3. Revegetation will be with native trees, shrubs and groundcovers.
  4. Pits will be made safe on completion of mining.
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