Groundwater

CIS Groundwater Response

The report acknowledges that groundwater levels & quality will be detrimentally affected through the construction process & then on an ongoing basis post construction.

GHD Expert report identifies & acknowledges 4 potential impacts to groundwater.

  1. Contaminated Groundwater Plumes. These result mainly from the Fitzroy Gasworks in precinct 2 but may have spread as far as precinct 1 & may be very deep. Contamination is in all 6 precincts. Asbestos also in precinct 3. There is also the problem of potential leaching from the cemetery.
  2. Contaminated and/or saline Groundwater inflow into the tunnel.
  3. Tunnel acts as a dam to regional groundwater flow.
  4. Potential “dewatering” causing subsidence.

Legislation apparently requires that groundwater must be improved or maintained.

Issues of concern that are not adequately addressed by the CIS are as follows

  1. There is no permit required for the use of groundwater. There are EPA Legislation & guidelines that provide a framework only. (Appendix M Page 2) Considering the potential impacts, a framework is inadequate. What obligation is there to follow the framework?
  2. To overcome the weakness at 1 above, the expert proposes a series of performance requirements to ensure the mitigation of risk & minimisation of impacts. There are no assurances that these performance requirements will be the final requirements or adhered to.
  3. The expert has said it will be up to contractor to determine the best approach to achieve the performance requirements. (Appendix M, page10). We do not accept that commercial interests should determine the method to ensure performance requirements. There are ample examples of self–regulation failing, especially when associated with commercial interests.
  4. According to the expert report (Appendix M page 11),  “Some innovation may be required to manage tunnel constructions and operations particularly for the Fitzroy Gasworks contaminated groundwater plume to minimise clean-up costs, protect the safety of workers and residents and enable ongoing clean-up and monitoring”. Unproven & experimental techniques are not acceptable. The project should not endanger the health of workers or residents.
  5. The expert report (Appendix M, page 11) suggests the project is unlikely to significantly impact the existing groundwater users, potential groundwater ecosystems, activate acid sulphate soils or water quality. We are concerned that this opinion is relying on the innovation & ingenuity of the contractor as outlined at 4 above. The expert also acknowledges there will be a detrimental effect on the groundwater but has not quantified the extent. What is an acceptable level of damage to the groundwater when one considers the impacts could be so vast? (Human & ecosystem health)
  6. The expert report has acknowledged that the contamination level from the Fitzroy Gasworks is high with over 50 separate contaminants identified. It has also acknowledged that the tunnel & portal works have the potential to mobilise (Appendix M, page 67) this contamination and hence spread the contamination to other areas. The potential extent of this mobilisation is not quantified. In addition, the works could alter the direction of groundwater flows due to the tunnel works and the damming effect of the tunnel. How far could this contaminated groundwater be spread in such a densely populated area and in what direction? How many people could potentially be endangered? These questions/impacts are not addressed.
  7. The expert acknowledges (Appendix M, page 67) that the project may also complicate future attempts to remediate the area from contamination. The project should not reduce the ability to clean up the groundwater contamination for future generations. This has not been addressed.
  8. The expert has acknowledged (Appendix M, page 67) the potential for subsidence caused by “de-watering” and resulting in changed groundwater level. This subsidence could manifest into unacceptable movement in buildings or damage to buried services. As it has been acknowledged that the tunnel will likely alter the groundwater flows during the construction phase and permanently due to the damming effect, what areas will be affected? There is no geographical quantification as to the extent of the damage. Who will bear the cost of monitoring the damage & repair to building & services?  The CIS fails to address these issues.
  9. The expert has acknowledged when quantifying mitigation measures (Appendix M, Page 68) “that metrics are either not available or not easily quantified for some events such as vegetation health should ground water levels change”. Because the metrics are unavailable / unknown is not an acceptable assessment of the risk. As the amount of vegetation within the inner city is minimal & hence so prized, destruction of any vegetation should be viewed as a major impact. Potential damage to vegetation within the Royal Park, its’ enclosed Zoo should be viewed as an abhorrent loss of amenity & an unacceptable risk. We do not accept the expert opinion of the acceptability of this risk.
  10. Precinct 1 will involve “cut & cover “technique to construct the portal. Like all precincts, this area has been identified as contaminated but has the additional concern of proximity to the highly contaminated precinct 2. The potential for contaminated dust, to be transferred in times of high winds has not been assessed.