Field studies in the Namoi

A new investigation of aquitards is commencing at three sites in the Namoi (Yarramanbah/Cattle Lane and Breeza Plain/Pullaming). The work is part of the National Centre for Groundwater Research and Training (NCGRT) Program 1B "Innovative characterization of aquitards" to be completed by the research team of UNSW Connected Waters, with several research collaborators. Led by Dr Wendy Timms and Professor Ian Acworth, the team includes post-doctoral researchers, students and technical officers. 

The Breeza plain site is located at the Agricultural Field Station (Department of Industry and Investment) and will potentially provide synergies with research by the Department and CSIRO including lysimeter systems. 

NCGRT aquitard research focuses on saturated sediments, hydraulic conductivity and storativity, and source and transport of contaminants including salts. The research will also examine preferential flow through and around aquitards via leaky bores and other discontinuities. The research will not specifically examine deep drainage, vadose zone fluxes or fracture flow, although there may be implications for understanding these processes as a result of aquitard research. 

This research builds on groundwater studies that were started many years ago. The research is not related to the Namoi Water study or exploration for gas and coal mining. 

Work at the Namoi aquitard research sites is to start in March 2010. The scope of the research at these two main research sites will include:

Drilling, sediment coring and installation of nested piezometers

  • 8 x 50 mm diam. piezometers at 5 m intervals to 40 m depth (separate holes)
  • 3 x 80 mm diam. grouted casings for geophysical testing
  • 1 x 140 mm diam. cored hole to 45 m depth
  • Total of 360 m drilling at two sites plus drilling at salinity hotspot piezometer south of Carrol

Geophysical surveys including downhole electrical tomography, seismics and micro-gravity to independently measure hydraulic parameters and moisture content.
Lab testing of sediment cores for physical and chemical index properties. 

Centrifuge permeameter testing of hydraulic and consolidation behavior of saturated low permeability sediments under in-situ stresses, and over long time periods.

Sampling and analysis of water chemistry and isotopes on site, and in nearby DECCW monitoring bores and the Mooki River. 

Monitoring of pore pressures in piezometers and correlation with rainfall and barometric pressure data to determine if piezometers in thick clay can be used as large scale lysimeters (low BE, high LE).

Numerical modelling of reactive transport modeling for saturated zone, focused on fluxes through and around aquitards. Numerical models of centrifuge permeameter experiments will also be developed to aid interpretation of findings. 

Leaky bore testing procedures at old bores and nested piezometer sites that have been installed in the same hole with bentonite grout seals.