Apr 20 2018
The Maules Creek Water Source Management Zone is part of the larger Namoi Water Sharing Plan (WSP). The Maules Creek Tributaries Management Zone (shown above) includes the Maules Creek coal mine which has a pump in the bottom of the pit that is de-watering the mine. This pump should, in theory, be covered by the Namoi WSP – but its all in the definitions.
The Maules Creek coal mine owns the 78 ML “Green Gully” water licence 12479 which is subject to the cease to pump rules in the Namoi WSP when less than 1 ML per day is flowing across Elfin Crossing.
The mine also owns the 138 ML licence (12811) that came with “Olivedeen” in Zone 5, the 3000 ML high security Namoi River licence (13050) and the newly created 300 ML Porous Rock licence (29588) which was granted on the 21st of June, 2012, for perpetuity.
The Porous Rock licence was granted just 4 months prior to the mines state planning approval on the 23rd of October 2012 and just 18 days after the Namoi WSP commenced on Oct 4, 2012.
The “Green Gully” 78 ML per annum licence is sufficient to cover the .25 ML per day that the groundwater modelling in the EIS estimated would be lost from from Zone 11 groundwater.
However 78 ML is insufficient to cover the output of the de-watering pump so the remainder of the de-watering of the pit (based on the groundwater modelling estimates) relies on the newly created Porous Rock licence and its exemption in the newly commenced 2012 Namoi WSP.
The WSP definition of Porous Rock would include coal seams.
“Porous Rock” means consolidated sedimentary rock containing voids, pores or other openings (such as joints, cleats and/or fractures) which are interconnected, in the rock mass and which are capable of transmitting water.
However the real world situation is not so cut and dry. We know from the geology of Maules Creek that the coal seams within the Maules Creek pit could extend out to underlie, intersect or otherwise connect to the Maules Creek alluvial aquifer.
But, unfortunately the Namoi WSP Part 1, section 4 (5) (a) specifically excludes water from the Porous Rock from water sources managed under the WSP.
This means that water pumped from the coal seams that originated from the alluvial aquifer could circumvent the Namoi WSP cease to pump triggers.
If there is any suspicion that the alluvial aquifer water that was running across Elfin Crossing is now draining into the mine pit, for full transparency, the de-watering pump should be metered like other pumps in the region. Then the groundwater model can be independently verified.
The Maules Creek mine NSW planning approval provides a mechanism for independent verification of the groundwater model. It might be time to do just this.
Section 40 of the PAC approval concerning the Water Management Plan says that the proponent shall prepare a plan that is acceptable to the Secretary of the Dept of Planning including a 3 yearly independent review of the groundwater model and a plan to “respond”.
- performance criteria for the following, including trigger levels for investigating any potentially adverse impacts associated with the project:
- the water management system;
downstream surface water quality;
downstream flooding impacts, including flood impacts due to the construction and operation of the rail spur line and mine access road, and flooding along Back Creek; and
stream and riparian vegetation health, including the Namoi River;
a program to monitor:
the effectiveness of the water management system; and
surface water flows and quality in the watercourses that could be affected by the project;
downstream flooding impacts; and
reporting procedures for the results of the monitoring program;
a plan to respond to any exceedances of the performance criteria, and mitigate and/or offset any adverse surface water impacts of the project; and
- a program to validate the groundwater model for the project, including an independent review of the model every 3 years, and comparison of monitoring results with modelled predictions; and
- a plan to respond to any exceedances of the performance criteria;
This Map and the legislative detail of the Namoi WSP for the Unregulated and Alluvial Water Sources is made under section 50 of the Water Management Act 2000.
According to the Namoi WSP, the Namoi Unregulated Rivers Water Sources include all water:
(a) occurring naturally on the surface of the ground within the boundaries of the Namoi Unregulated Rivers Water Sources shown on the Plan Map, and
(b) in rivers, lakes and wetlands within the boundaries of the Namoi Unregulated Rivers Water Sources shown on the Plan Map.
These water sources do not include water:
(a) contained in any fractured rock or porous rock,
(b) contained in the water sources to which the following water sharing plans apply:
(c) taken under a floodplain harvesting access licence with a share component that specifies a water source to which this Plan does not apply,
(d) contained in the sections of the watercourses specified in Column 2 of Schedule 1.
Groundwater Dependent Ecosystems (GDE):
Despite the presence of Stygofauna in the Maules Creek Alluvial Aquifer, the Namoi WSP does not identify any high priority GDE’s.