The UKHP requires the construction of approximately 22 kilometres of tunnels. The tunnels will be bored through high grade metamorphic rocks. The transmissivity of this type of rock is low so groundwater flows occur along discontinuities such as cracks and fault plains. The tunnels are therefore unlikely to draw down groundwater except where the tunnel crosses a discontinuity. At these points there is potential for groundwater flows into the tunnel to occur resulting a drop of groundwater levels at the surface.
Potential impacts from groundwater drawdown include:

• drying up of existing surface water bodies, such as wells, ponds and groundwater fed streams;
• drying up of paddy fields;
• reduction in soil moisture and fertility; and,
• changes in vegetation.

The boring of the tunnels may give rise to the following impacts:

• generation of large amounts of tunnel waste requiring disposal;
• incorrect disposal of tunnel waste impacting on local water courses from increased sedimentation;
• contamination of local water courses through disposal of tunnel waste water without treatment; and,
• incorrect storage of grouting materials, fuel and other hazardous materials causing contamination of ground and water.

Extensive studies have already been conducted to assess local groundwater conditions, these have included the drilling of test adits into cracks and fault planes along the tunnel alignment.

Results show that the cracks and faults appear to be ‘tight’ and do not allow any downward flow of groundwater.

Monitoring of groundwater levels will be conducted throughout the construction period and the results will be posted on this web site.