381_M_05_Rev0 - WUG Monitoring and Testing Program 3 Stage 4: Installation of operational monitoring and implementation of ongoing mitigation measures. 8. Conduct progress grouting and drainage within tunnels and drive. If confirmed by modelling, complete localised depressurisation and grouting of the upper horizons of the mine before mining. Analyse monitoring data and adapt measures progressively. 9. Once pathways are sealed at a sufficient level and without disturbing the natural groundwater flow to the surface water systems, implement dewatering measures (deep hole dewatering, sump pumping, drainage and depressurisation), while continuously monitoring shallow and deeper water levels and potential responses to these measures. 10. Apply a progressive (P) mitigation measures design (D) and implementation (I) strategy consistent with the TARPs and the OM framework. Monitor impact and conduct secondary and tertiary grouting from UG infrastructure as required. 2.2. CONSENT CONDITIONS AND PROJECT PHASING As part of the consent process, OGNZL and their technical and environmental planning advisors have developed a series of conditions targeted at implementing a series of tasks, from the data acquisition and monitoring stage, through the modelling of impact, the development of water management plans and associated TARPS, to the ongoing reviews by the Select Panel. The consent conditions are consistent with the policy framework which applies to the waterbodies of the Waikato Regional Plan and imply that “the activities authorised must not cause any measurable changes in the natural flows or water quality in any surface water body identified as a Natural State Water Body in the Waikato Regional Plan at the date of issue of the consent, except for those changes caused by the warm spring”. The conditions, derived from the mitigation measure strategy developed for the WUG encompass the following key elements: • Establishment of baseline groundwater conditions (piezometry and water quality), groundwater and surface water interaction, and inclusion in numerical model development. • Further data acquisition and analysis (including 3D numerical modelling) during the lodgement phase. • Development of a Mine Area Groundwater Management Strategy, Rehabilitation and Closure Plan and associated TARPs (covering the exploration, pre-development, operational, closure and post-closure phases). • Implementation of exploratory and operational monitoring, testing and mitigation measures program. • Updated numerical analyses based on any resulting deviation from the established baseline and to account for dynamic effects (e.g., time-series data and the seasonal variations to recharge mechanisms), and the use of dynamic responses to refine the groundwater and surface water interaction. • Engagement of a Select Panel of Peer Reviewers and implementation of an ongoing review process. A pathway from the lodgement of the application, to the operating phase of the mine has been developed around the conditions proposed by OGNZL and the supporting measures presented in the VE Phase 1 report (summarised in Section 2.1). The project timeline shown in Attachment A, presents the sequencing and interdependency between the various steps of the Mine Area Groundwater Management Strategy, and covers the investigative and operational phase of the mine. The timeline excludes the mine closure phase at this stage.
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