www.valenza-engineering.com 381_R_04_Rev 0 OGNZL_WUG_Phase1_Conceptual_Mitigation 43 8. MONITORING AND TRIGGER POINTS 8.1. DEVELOPMENT OF MONITORING NETWORK 8.1.1. SURFACE WATER – GROUNDWATER INTERACTION PIEZOMETERS In agreement with OGNZL and FloSolutions, between 9 and 12 nested piezometers are planned for installation near streams to investigate groundwater levels, the interaction between surface water bodies and the vertical groundwater gradient. Because of the access restrictions in the current Access Agreement, these will be drilled with an L140 man-portable drill rig. To facilitate multiple uses for the well (VWP installation, hydraulic testing, water sampling etc.), VE proposes that VWPs are installed at multiple depths across the hole depth extent and grouted to the expected depth of the shallow hole. A PVC standpipe sits atop the grout at the required depth allowing hydraulic testing and sampling in a shallow monitoring bore. The testing proposed includes standard borehole hydraulic tests (e.g., slug tests and constant head tests), and where applicable and permissible withing the AA, groundwater pumping tests. These additional piezometers are required to address the following areas of uncertainty within the current conceptualisation: • Analysis of natural dynamic stress from seasonal rainfall responses in groundwater levels. • Assess the potential groundwater pathways that may be present within the rhyolite flow dome (Drill Site 1 piezometers). • Assessment of the presence and effectiveness of natural flow barriers identified in conceptual model. The proposed location of the piezometers is presented in Figure 8-1 (and Appendix G and H).
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