Wambo - DA 305-7-2003 MOD 17 Briefing 6 December 2017 Albert - - PowerPoint PPT Presentation

Wambo - DA 305-7-2003 MOD 17 Briefing

6 December 2017 Albert Scheepers – General Manager Micheal Alexander – Dir. Projects & Portfolio Management NSW Steven Peart – Manager Environment & Community

1. Overview of MOD 17. 2. Subsidence effects and impacts. 3. Groundwater and surface water conclusions. 4. Proposed conditions. 5. Justification of Modification.

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Agenda

• Continued use of South Bates Underground coal handling

infrastructure located within the Bates South pit.

• Two additional ventilation shafts within existing approved

disturbance area.

• Gas drainage boreholes would be restricted to grassland.
• Delay in the commencement of South Wambo Underground

to allow for access to this coal.

• Extends the life of the operations by 7 years.

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Overview of MOD 17

Modification Components

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Overview of MOD 17

• 18 Mt of ROM coal from

the Whybrow Seam.

• Whybrow Seam

extensively mined at Wambo.

• Wholly Wambo-owned

land.

• Adjacent to existing open

cut and underground mining areas.

• No changes to the open

cut operations.

• No change to maximum

production rates or coal handling operations.

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Subsidence Effects and Impacts

Extent of Conventional Subsidence Wollemi Escarpment

• Extensive working knowledge of the Whybrow Seam and

high degree of confidence in prediction modelling.

• Subsidence impacts would continue to be managed in

accordance with:

• Subsidence impact performance measures in the

consent.

• Extraction Plan process – detailed management and

monitoring.

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Subsidence Effects and Impacts

Management of Subsidence Impacts

• No additional impacts on surrounding water supply.
• Incremental impacts are generally confined to the extent of the

Modification longwalls.

• Numerical model developed by Dr Noel Merrick.
• Calibrated against 11 years of continuous monitoring data

(2003 – 2014).

• Peer reviewed by Dr Frans Kalf.

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Groundwater and Surface Water Conclusions

Groundwater Assessment Conclusions

• North Wambo Creek has been diverted around the approved

Wambo open cut operations.

• North Wambo Creek is ephemeral.
• The catchment area of North Wambo Creek is approximately

2% of the catchment area of Wollombi Brook at Warkworth.

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Groundwater and Surface Water Conclusions

North Wambo Creek

Water Supply

• No water used for domestic or stock along the complete length of

North Wambo Creek.

• Classified as “less productive” by CLWD (formerly DPI Water).
• No privately-owned land along North Wambo Creek.

Ecological Values

• No permanent pools in the section of North Wambo Creek that

would be undermined by Longwalls 23 to 25.

• 1 km of the length above LW 23 and 24 has been historically

cleared for agriculture.

• Remaining vegetation is fragmented and affected by previous

grazing activities.

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Groundwater and Surface Water Conclusions

Values of North Wambo Creek

• Anticipated to be similar to impacts elsewhere on North Wambo

Creek and the Diversion where subsidence has already occurred at similar mine geometries:

• Creation of semi-permanent or permanent pools.
• Surface soil cracking and changes in grade that may require local

scour protection works or remediation.

• Direct hydraulic connection has not been observed:
• Extraction of South Bates Underground LWs 11 to 13 (2016 – 2017)

beneath North Wambo Creek Diversion.

• Extraction of North Wambo Underground LWs 1 to 8a (2008 – 2015)

beneath North Wambo Creek (downstream of the Modification area).

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Groundwater and Surface Water Conclusions

Potential Impacts on North Wambo Creek

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Groundwater and Surface Water Conclusions

• Hunter Lowland Redgum Forest.
• Not considered by Dr Colin Bower

to be groundwater dependent.

• Recent drilling in the area showed

the depth to groundwater is 4.8 to 13.8 m.

• Groundwater table is generally in

consolidated bedrock below colluvium (generally not suitable for rooting).

• Significant monitoring programs

have been undertaken at Wambo in areas of undermined

• vegetation. No observable effects

to vegetation health due to reduced access to groundwater have been recorded at Wambo.

• Conditions require Wambo to meet subsidence impact performance

measure:

• Limited to - minor cracking and ponding of the land surface or other impact.
• Negligible environmental consequences.
• Failure to meet these measures is a non-compliance and also

requires an offset of the impact.

• The Extraction Plan provides further detail and confidence about

meeting these measures and how performance will be assessed.

• Wambo will conduct further studies into the potential groundwater

dependence of the riparian vegetation along North Wambo Creek.

• 4 years of mining prior to Longwall 25.

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Proposed Conditions

Riparian Vegetation

• Underground mining and subsidence within WCPL owned land.
• Enables continued use of Wambo infrastructure and workforce.
• Economic recovery of coal resource that would otherwise not be

recovered.

• Facilitate continuity of underground operations (230 personnel).
• Additional royalties in the order of $66 M (NPV).
• Economic and social benefits in the Wambo region associated with
• ngoing employment opportunities and expenditure.

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Justification for Modification

Highlights