White was presenting at the New South Wales Minerals Council’s 2006 Environment and Community Conference in Wollongong.
The NPSS, located adjacent to New South Wales’ Blue Mountains, are listed as Threatened and Endangered Ecological Communities under the Federal Environment Protection and Biodiversity Conservation Act 1999 and the NSW Threatened Species Conservation Act 1995.
Centennial Coal operates three underground mines – one bord and pillar and two longwall – which extract coal from 160-380m beneath NPSS near Lithgow.
Together the mines produce about 7 million tonnes per annum and directly employ approximately 600 personnel. The minimum mine life is in excess of 10 years.
Approximately 12 NPSS lie over areas planned for mining in the next 10 to 15 years.
Potential impacts to the area from mining include changes in surface and groundwater hydrology through surface and overburden cracking.
For the past five years Centennial has undertaken hydrological and ecological studies to gain an understanding of the biophysical requirements for NPSS formation, health and longevity and predict and quantify the potential impacts of Centennial’s mining operations on these swamps, White said.
A NPSS Management Plan was developed by Centennial in consultation with the Biodiversity Unit and the Department of Primary Industries.
The monitoring program includes surface-to-seam aquifer monitoring, stream flow monitoring and flora and fauna monitoring simultaneously in NPSS subjected to mining and controls sites.
Surface aquifer monitoring consists of piezometers installed to a maximum of 8m in or adjacent to NPSS subjected to mining. Deeper aquifer monitoring has been undertaken in all aquifers down to the coal seam by vibrating wire piezometers. Readouts from these piezometers are collected by data loggers at hourly intervals prior to, during and after mining.
Stream flow monitoring is undertaken in streams in and away from the mining area using a pygmy stream flow meter. Flora and fauna monitoring consists of monitoring fixed quadrats for diversity and abundance prior to, during and after mining.
Data collected is used for the generation of diversity and abundance indices. Rainfall on the plateau is also recorded.
Across the Centennial mining area the monitoring program consists of continuous groundwater monitoring (21 piezometers); fortnightly surface water monitoring (flows and quality – 14 sites); seasonal flora monitoring (36 quadrats); seasonal fauna monitoring within the swamps (10 sites); photographic monitoring and visual inspections of swamps; rainfall and temperature monitoring; and subsidence monitoring.
“Aquifer study results to date indicate that the surface water tables associated with the NPSS have not been negatively affected by either bord and pillar or longwall mining techniques,” White said.
“The results do indicate, however, that the prolonged drought on the Newnes Plateau is having a significant effect on surface water table levels.”
Flora and fauna studies have also confirmed no significant impact from mining.
