EGL Ref: 9018 22 June 2022 Page 13 WAI-985-000-REP-LC-0006_Rev0.docx This report shall only be read in its entirety. flows in the tributary TB1, which flows from the southeast near the existing Northern Stockpile, to northwest across the proposed NRS site, are to be considered in the design of the new stream diversion. 8.0 DESIGN BASIS 8.1. Geotechnical stability The proposed design criteria for the NRS are summarised in Table 1. TABLE 1: SUMMARY OF PROPOSED GEOTECHNICAL DESIGN CRITERIA Design Parameter Design Criteria Earthquake loading • Operational Basis Earthquake (OBE) Probabilistic 150 year return period • Safety Evaluation Earthquake (SEE) Probabilistic 2,500 year return period Geotechnical stability • Static • Seismic - Temporary benches in stockpile Factor of Safety (FOS)≥1.2 - Rehabilitated benches in stockpile Factor of Safety (FOS)≥1.5 - Stockpile global stability FOS≥1.5 - Post-earthquake conditions FOS 1.2 OBE: The performance requirement for the OBE is that the NRS remain functional and that the resulting damage is minor and easily repairable. SEE: The performance requirement for the SEE is that there is no major instability when the NRS is subjected to the seismic load imposed by the SEE. Damage to the structure (liner, drains, capping) may have occurred, however, it is readily recoverable. 8.2. Uphill diversion drain sizing The uphill diversion drain will be sized for a minimum requirement of a 10 year ARI (Average Recurrence Interval) flow, equal to the existing resource consent conditions (RC971307, RC971309, Condition 4).
RkJQdWJsaXNoZXIy MjE2NDg3