Summary
Numerical groundwater modelling results are primarily presented as the difference in groundwater drawdown between two possible futures – the baseline and the coal resource development pathway (CRDP). In bioregional assessments (BA) the baseline includes all coal mines and CSG fields that are commercially producing as of December 2012. The CRDP includes all baseline plus any additional coal resource developments (ACRD) continuing into the future. The ACRD is defined as all coal mines and CSG fields, including expansions of baseline operations, that are expected to begin commercial production after December 2012. The Maranoa-Balonne-Condamine subregion coal resource development pathway (CRDP) includes five baseline open-cut coal mines, five baseline coal seam gas (CSG) projects and two open-cut coal mine project proposals.
Open-cut coal mines are represented in the revised Office of Groundwater Impact Assessment (OGIA) model using the MODFLOW Drain package. The five baseline coal mines are: Cameby Downs Mine, Commodore Mine, Kogan Creek Mine, New Acland Coal Mine Stage 2 and Wilkie Creek Mine (which ceased operations in December 2013). The two proposed coal mines are: New Acland Coal Mine Stage 3 and The Range. For each mine, OGIA and the Assessment team used publicly available information to delineate the extent of operational and proposed pits to represent coal mines in the revised OGIA model. The Drain cell elevation in the model layer representing the Walloon Coal Measures is set to either the mean coal seam depth or the bottom of the model grid cell. This approach means that groundwater levels are drawn down over the entire model grid cell where a pit is present, which may tend to overestimate groundwater drawdown associated with open-cut mine pit dewatering.
Groundwater extraction associated with CSG is simulated in the OGIA model using the MODFLOW EVT package. The five baseline CSG projects are: Australia Pacific LNG Project, Queensland Curtis LNG Project, Santos Gladstone LNG and GLNG Gas Field Development projects, Surat Gas Project and Ironbark Project. To ensure consistency with OGIA reporting, the baseline includes all CSG projects in the Maranoa-Balonne-Condamine subregion that are reported in the 2014 annual report for the Surat cumulative management area. The OGIA model includes information on historical and predicted future CSG extraction rates provided to OGIA by the tenure holders each year.
Numerical groundwater modelling results are primarily presented as the difference in groundwater drawdown between two possible futures – the baseline and the coal resource development pathway (CRDP). In bioregional assessments (BAs), the CRDP includes all baseline plus any additional coal resource development (ACRD) continuing into the future. The baseline is defined as a future that includes all coal mines and coal seam gas (CSG) fields that are commercially producing as of December 2012. The ACRD is defined as all coal mines and CSG fields, including expansions of baseline operations, that are expected to begin commercial production after December 2012. To ensure consistency with Office of Groundwater Impact Assessment (OGIA) reporting, the baseline includes all CSG projects in the Maranoa-Balonne-Condamine subregion that are reported in the 2014 annual report for the Surat cumulative management area (CMA) (OGIA, 2014).
The Maranoa-Balonne-Condamine subregion CRDP includes five baseline open-cut coal mines, five baseline CSG projects and two open-cut coal mine project proposals. The CRDP is informed by companion product 1.2 for the Maranoa-Balonne-Condamine subregion (Sander et al., 2014) and is described in more detail in companion product 2.3 for the Maranoa-Balonne-Condamine subregion (Holland et al., 2016). The CRDP is based on information available as of July 2015 and was finalised after feedback provided at the CRDP workshop that was held in December 2014 in Toowoomba. The location and development timeline of the coal resource development projects represented in the numerical groundwater model for the Maranoa-Balonne-Condamine subregion are shown in Figure 9 and Figure 10, respectively.
Figure 9 Modelled coal resource development in the Maranoa-Balonne-Condamine subregion
In this figure, results are presented for only that part of the coal resource development pathway (CRDP) that can be modelled.
ACRD = additional coal resource development, APLNG Project = Australia Pacific LNG Project , LNG = Liquefied Natural Gas, OGIA = Office of Groundwater Impact Assessment, QCLNG Project = Queensland Curtis LNG Project , QGC = Queensland Gas Company, GLNG Project = Santos Gladstone LNG Project + GLNG Gas Field Development Project
Data: Bioregional Assessment Programme (Dataset 1, Dataset 2, Dataset 3), Office of Groundwater Impact Assessment (Dataset 4).
In this figure, results are presented for only that part of the coal resource development pathway (CRDP) that can be modelled.
Construction and production are assumed to occur concurrently due to the staged development process of the coal seam gas development projects.
ACRD = additional coal resource development, APLNG Project = Australia Pacific LNG Project, GW = groundwater, LNG = Liquefied Natural Gas, QCLNG Project = Queensland Curtis LNG Project, QGC = Queensland Gas Company, Santos GLNG Project = Santos Gladstone LNG Project + GLNG Gas Field Development Project
