SECTION 4 Groundwater Effects Assessment – Willows Farm Access Tunnel 26 The model results confirm that the long-term drawdown in groundwater levels associated with the construction of the tunnel are small and would be indiscernible within 600 m distance of the tunnel. The majority of the drawdown effect will remain within the Willows Farm property, with some effect extending into DOC land. Given the nature of the weathered tuff, only a limited amount of compressibility is likely to exist. Assessing the amount of drawdown that might occur, only a limited amount of settlement is possible and this would mostly be directly over the tunnel alignment. The primary rockmass being dewatered is the Rhyolite body and this is a hard, incompressible medium and is not expected to consolidate significantly as a result of dewatering. This has been assessed in detail in the EGL report (WAI985-000-REP-LC-0050). 4.3.9 Potential for Effects on Plant Growth Any dewatering associated with the tunnel will be in the deeper rockmass. Soil moisture conditions in the regolith soils or terrace deposits in the near surface are not expected to change as a consequence of dewatering the deeper rocks. We therefore consider the effects of tunnel dewatering on plant growth to be less than minor.
RkJQdWJsaXNoZXIy MjE2NDg3