fingerboards mineral sands project · 2019. 10. 16. · method the water studies ... technical...

Kalbar Resources Ltdwww.fingerboardsproject.com.au | [email protected] Bailey Street, Bairnsdale VIC 3875 | Office Tel +61 3 5152 3130 | Freecall 1800 791 396

of 4 Technical Study Information Sheet No.10 –

Water Study | May 2019

Fingerboards Mineral Sands ProjectInformation Sheet - Water Study

BackgroundA wide range of surface water and groundwater studies were completed by specialists for the Fingerboards Mineral Sands Project, including:

• Surface water and groundwater impact assessment report (Coffey Services).

Surface water:

• Conceptual surface water management strategy and water balance (EMM).

• Landscape stability and sediment transport regime assessment (Water Technology).

• Surface water assessment – site study (Water Technology).

• Surface water assessment – regional study (Water Technology).

• Mine contact water quality assessment (EGi).

Groundwater:

• Groundwater modelling report (EMM).

• Tailings seepage assessment (EGi).

This Information Sheet contains information obtained directly from the studies.

MethodThe water studies characterised the surface water and groundwater systems within the vicinity of the mine and investigated the effects of mining on the environmental values of water. The environmental

values were adopted from the beneficial uses of water as defined by the State Environment Protection Policy (Waters).

The surface water study area was defined by the Mitchell River catchment to the east and the Perry River catchment to the west, which includes the Gippsland Lakes. The groundwater study area extends 10 km south of the project area (in the inferred direction of regional groundwater flow), and 5 km east and west.

A desktop review and field investigation were conducted to define the surface water and groundwater systems and collect baseline water quality data. The field investigation included:

• Drilling and installation of groundwater observation wells.

• Aquifer hydraulic testing.

• Groundwater level gauging.

• Groundwater sampling and laboratory analysis.

• Surface water sampling and laboratory analysis.

This data was used to establish groundwater values within all aquifers, and surface water values within mine site drainage gullies, Mitchell River, Perry River, Providence Ponds, Avon River and the Gippsland Lakes. Further investigations and modelling were conducted to inform a risk-based assessment of project impacts to the groundwater and surface water values.

Technical studies are being prepared to inform the Environment Effects Statement for the Fingerboards Mineral Sands Project. This information sheet provides an overview of the scope and initial findings of the surface water and groundwater studies.




Objective of the StudyThe evaluation objective for catchment values as outlined in the Scoping Requirements for the Environment Effects Statement is:

‘To minimise effects on water resources and on beneficial and licensed uses of surface water, groundwater and related catchment values (including the Gippsland Lakes Ramsar site) over the short and long-term’.

Existing conditionsThe project area spans the Mitchell River basin to the east and the Thomson River basin to the west. Surface water drainage within the project area is either modified and impacted creeks or gullies,

many of which drain to small farm dams. The small, ephemeral drainage lines are typically dry and flow only after high-rainfall storm events. Water quality samples were collected from Perry Gully, Simpson Gully, Long Marsh Gully and Honeysuckle Creek. Water quality in the project area was found to exceed some water quality guidelines for the water dependent ecosystems (i.e., aquatic ecosystems), potable water supply and agriculture and irrigation beneficial uses.

Notable surface water systems surrounding the project area include the Mitchell River, Perry River, Providence Ponds and the Gippsland Lakes.

Some streams and rivers within and immediately surrounding the project area are dependent on groundwater. Groundwater dependent ecosystems were mapped along Long Marsh Gully, Perry Gully, Simpson Gully, Lucas Creek, Moilun Creek and unnamed tributaries of the Mitchell River. The project is located within the northern margin of the Central Gippsland groundwater basin. Groundwater is also present in shallow alluvial deposits associated with the Mitchell River valley and is primarily recharged by the river during high flow and flood events.

Baseline groundwater conditions in the shallow aquifer were reported to exceed the adopted beneficial uses water quality guidelines for the water dependent ecosystems and species, potable water supply, irrigation and water-based recreation.

Above: Example of a dry drainage gully within the project area (Source: Coffey Services).

Above: Example of a farm dam within the project area (Source: Coffey Services).

Above: Mitchell River (Source: Coffey Services).




Key FindingsSite Water BalanceA site water balance was developed for the project by EMM using GoldSim version 12.0 modelling software. Historical climate data, including 117 years of daily rainfall data and evaporation, was used to assess the performance of the proposed water management system. A climate change scenario was also assessed. The model determined the annual water inputs and outputs for low, median and high rainfall conditions for three snapshot mining scenarios (Years 5, 8 and 15). The water balance results indicate that:

• Groundwater supply may be required during dry years to supplement the assumed winter-fill allocation from the Mitchell River.

• The system is capable of offsetting runoff intercepted by the water management dams.

• Catchment water on site will be retained so that the probability of discharge in any year is less than 3% to the Mitchell River and less that 1% to the tributary of the Perry River.

Sediment Generation and TransportA landscape stability and sediment transport assessment for the Fingerboards Mine was conducted by Water Technology. The primary purpose of the study was to identify the potential for sediment generation and transport that might arise during construction, operations and post-closure.

The study found that the retention of rainfall runoff from the mine area in onsite water management dams will result in less erosion, reduced sediment load and reduced advancement of existing landscape instabilities.

Site and regional surface water assessments were conducted by Water Technology and found no adverse impacts to the Mitchell and Perry River systems from project activities with the exception of moderate increases in total suspended

solids (TSS) and nutrient concentrations above background levels for short periods of time during potential dam spillway releases to the Perry River system.

Water Technology also assessed the potential effects of altered topography and flow regimes during construction, operation, and post-closure on flood response. Water Technology concluded that the water management strategy largely mitigates the risk of flooding within the mine area.

GroundwaterNumerical groundwater modelling was undertaken by EMM to provide a predictive basis for the assessment of groundwater impacts and groundwater baseflow to the Mitchell River.

The modelling demonstrated that groundwater mounding may develop beneath the mine area due to infiltrated seepage from tailings. Geochemical characterisation work by EGi was undertaken to predict the quality of tailings seepage. Metals concentrations in tailings were lower than the mean concentrations that naturally occur in the shallow groundwater in the project area and therefore do not represent a hazard to groundwater value.

Impacts on the water balance of key receptors was also investigated by the groundwater model and found to be insignificant, with the largest change expected not to exceed 1.2%, corresponding to a small increase in baseflow reporting to the Mitchell River. Insignificant effects are predicted for the Gippsland Lakes system, Providence Ponds, the Perry River, the Woodglen aquifer storage and recovery site and the Boisdale groundwater resource which is the primary water supply for the town of Sale.

Following the adoption of the recommended Environmental Performance Requirements and implementation of proposed mitigation measures, the residual risk to groundwater and surface water values was assessed as very low to low.




If you have any comments or questions about the technical studies, please contact us:Email: [email protected]: 03 5152 3130Freecall: 1800 791 396An enquiry form is available at: www.fingerboardsproject.com.au/contact

Management MeasuresTwenty-six separate mitigation and management measures were identified to reduce the predicted impacts on surface water and groundwater values. Key mitigation measures include:

• Recover and reuse water where practicable and optimise operations to maximise water use efficiency.

• Development and implementation of a Water Risk Treatment Plan to minimise discharge of stormwater from the operational mine areas.

• Rainfall runoff will be retained to less than 10% annual-exceedance-probability (i.e., less than 10% probability of discharge occurring in any year).

• Water storage dams will be engineered or constructed to reduce infiltration to groundwater.

• Water that has been in contact with disturbed areas from outside of the mine void or tailings storage facility that is retained in water management dams will be offset by water from the fresh water storage dam to maintain downstream environmental flows.

• Clean water will be diverted around the mine where possible (offset where not).

• Freeboards on the tailings storage facility, freshwater storage dam, process water dam and sedimentation ponds will be maintained to allow for storm events and high rainfall periods, in accordance with Australian and Victorian regulatory requirements.

• A groundwater monitoring network will be installed to assess the effect of extracting groundwater on Latrobe Group aquifer and the unconfined shallow aquifer.

• Stream bed instability will be identified and monitored prior to and during construction, operations, closure and post closure, and if required, erosion potential will be addressed through grade controls. Annual inspections will be made during construction and operation.

Project impacts and environmental performance will be monitored through a detailed groundwater (quality and level) and surface water monitoring program to be implemented for the life of project. Environmental monitoring data will be regularly reviewed and compared to predictions.

fingerboards mineral sands project · 2019. 10. 16. · method the water studies ... technical...

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