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

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

Overview of MOD 17 Modification Components • 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. 3

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. 4

Subsidence Effects and Impacts Extent of Conventional Subsidence Wollemi Escarpment 5

Subsidence Effects and Impacts Management of Subsidence Impacts • 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. 6

Groundwater and Surface Water Conclusions Groundwater Assessment Conclusions • 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. 7

Groundwater and Surface Water Conclusions North Wambo Creek • 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. 8

Groundwater and Surface Water Conclusions Values of 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. 9

Groundwater and Surface Water Conclusions Potential Impacts on 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). 10

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. 11

Proposed Conditions Riparian Vegetation • 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. 12

Justification for Modification Highlights • 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 ongoing employment opportunities and expenditure. 13