EGL Ref: 9216 22 June 2022 Page 18 File: WAI-983-080-REP-GT-0013_Rev0.docx This report shall only be read in its entirety. 14.0 EMERGENCY PLANNING The dam breach inundation map for the Rainy Day scenario with the modelled 1 in 100 year Ohinemuri River Flood is provided in Appendix D. The 1 in 100 year flood is a more likely flood scenario than the 1 in 1,000 year flood. The 1 in 100 year map and the 1 in 1,000 year map (Appendix C) can be adapted for the EAP for Storage 3. 15.0 CONCLUSIONS The proposed Storage 3 is to be constructed with the embankment crest at RL155. A dam breach study has been undertaken, the consequences of the breach assessed and the Potential Impact Classification (PIC) of the embankment determined in accordance with the guidance in Module 2 of the New Zealand Dam Safety Guidelines. The Storage 3 embankment is assessed to be High PIC. The breach study is based on hypothetical scenarios which are not connected to the probability of occurrence. A TSF that is appropriately designed, constructed, operated, and maintained in accordance with modern standards (e.g., NZDSG and GISTM, Refs. 1 & 3) would have a low and acceptable risk of failure. The dam breach maps developed as part of this assessment are to inform the Emergency Action Plan prepared to manage the response in the unlikely event of a breach.
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