Oceana Gold New Zeland Limited Hydrogeology Support for WKP Underground Updated Conceptual Model 1. FloSolutions S.A. Peru (FloSolutions) was contracted by OceanaGold New Zealand Limited (OGNZL) for hydrogeology support services in relation to the Waihi North Project, including the Wharekirauponga Underground Mine development ( ). The scope of these services is detailed in the FloSolutions proposal dated 25 January 2022 (document 101-22-104-02). This report summarizes results of data analyses and evaluation and presents an updated conceptual hydrogeologic model for the project, with a focus on the EG Vein system. 1.1. The proposed project is located north of Waihi, New Zealand in the Coromandel Ranges. The orebody and proposed mine is situated beneath land administered by the Department of Conservation (DOC). Access is limited and minimizing disturbance to the surface environment is a critical consideration in obtaining landowner and regulatory approvals. Due to difficulties associated with obtaining an Access Arrangement (AA) and development on OGNZL lands, OGNZL intends to access the orebody through development of a decline. The decline would be established on lands to the south near Waihi, and advanced northwards approximately 6 kilometers to access the orebody from underground. OGNZL is concerned about the potential for the underground mine development to impact on shallow groundwater systems and surface water bodies in the development area and has been undertaking studies and evaluations to assess these interactions. 1.2. A key project development challenge identified by OGNZL will be regulatory approvals and stakeholder acceptance, given the project location in sensitive DOC lands and the potential for environmental impacts from surface water capture and baseflow loss. Key questions identified in the surface water / groundwater assessment (Golder 2021, Section 2.2) include: For the project, the potential for water losses, stream capture, and local vs. regional dewatering during mine development will be driven by the large-scale connectivity of the fracture systems at the mine to a broader hydrogeological system and/or sources of water. To obtain project approvals, it will be necessary to demonstrate that OGNZL understands (and can quantify) the relationships between the surface water and groundwater system, the potential for ingress / stream capture, and the expected improvements that will be made by implementation of the mitigation measures. The field testing program undertaken by OGNZL and Golder in 2021 was designed to generate
RkJQdWJsaXNoZXIy MjE2NDg3