HVO 2009 Annual Environmental Management Report - Final

Coal & Allied – Hunter Valley Operations
Water Inputs
Water was supplied predominantly from three sources in 2009:
Surplus mine water stored in pit;
Intercepted runoff water; and
Groundwater percolation into the open cut.
A total of 564mm of rainfall was recorded at HVO in 2009 producing an estimated 7,485ML of runoff from
approximately 4,500ha of developed, disturbed and mining catchments. Water falling on undisturbed clean
water catchments is diverted off site into natural systems where possible. Rainfall runoff was the largest input
to the site mine water balance in 2009.
Groundwater contributed approximately 1,251ML to the site water supply.
Independent groundwater Modelling of the pits which comprise HVO indicate a portion of total groundwater is
contributed from connected Hunter River alluviums. Table 14 lists the Modelled amounts of water entering the
pit and the reference from which the number is generated.
Alluvial groundwater intercepted in North Pit was measured based on pump out rates during active mining in
this area. Since that time the pit has been back filled with spoil and the water level has risen to the base of the
barrier wall, hence seepage from the river alluvium will have reduced significantly. The seepage figure
provided is considered an overestimate. No Modelling has been undertaken to determine seepage rates with
the current conditions in North Pit.
Table 14: Modelled or Measured Groundwater Contribution from Connected Hunter River Alluvium
Pit
Alluvial Groundwater
Intercepted (ML/Day)
Source
Reference
Cheshunt 0.22 Hunter River MER 2005
Barrys 0.22 Hunter River Coffey 2008
North Pit
(Alluvial lands)
0.55 Hunter River Measured
Carrington 0.07 Hunter River MER 2010
Mackie Environmental Research (2005), Assessment of River Leakage Within the Cheshunt Pit Buffer Zone,
Amended Report, April.
Coffey Geotechnics (2008), Preliminary Groundwater Modelling Study, Cheshunt Pit, HVO South Coal
Project, July.
Mackie Environmental Research (2010), Carrington Extended- Review of Mining Related Impacts on the
Paleochannel Groundwater System.
Groundwater intercepted from connected surface alluviums is estimated to have contributed 387ML to the site
during the reporting period. HVO has a high security licence entitlement for 2,685ML of water in Zone 1B of
the Hunter River. Inflow from Hunter River alluvium is deducted from this entitlement.
No fresh water was pumped from the Hunter River during the reporting period. Freshwater usage is expected
to remain low in 2010 due to a large volume of stored mine water at the end of 2009.
All water extracted from the Hunter River is recorded against Water Access Licences issued by NOW. Refer
to Section 1.2.1 (Table 3) for details of these licences.
AEMR 2009 42