EGL Ref: 9216 22 June 2022 Page 16 File: WAI-983-080-REP-GT-0013_Rev0.docx This report shall only be read in its entirety. this damage is likely in 1 in 1,000 year flood also and is only expected to be marginally worse with a breach. Flooding damage is likely to result in shortterm road closure and restrictions on traffic while repairs are undertaken. However, most of SH2 is anticipated to have low damage and minor erosion. Localised overtopping of the Ohinemuri River stopbanks near Paeroa are anticipated under the Rainy Day breach scenario with a 1 in 1,000 AEP flood. The overtopping could erode the stopbanks. Repair of the damaged section is likely to be localised and is likely to take months. There are also non-critical or minor infrastructure assets that are susceptible to damage, including several roads in Waihi and Paeroa townships. Considering the extent of damage on SH2 and the number of roads and bridges affected by the incremental effect of the dam breach flood and deposited sediments, we anticipate the restoration of major infrastructure to normal operation would take more than a year, which is primarily associated with the repair of Storage 3. The impact of Rainy Day breach on critical or major infrastructures is assessed to be catastrophic. 12.2.6. Potential Impact on Natural Environment The potential incremental impact of a Rainy Day breach scenario of Storage 3 on the natural environment would be major and restoration of the Ohinemuri River and farmland adjacent to the river and Ruahorehore Stream would be costly and time consuming. The extent of area impacted by a Rainy Day breach scenario is significantly wider than that of a Sunny Day breach scenario, as it includes the Gilmour Reserve and flood plain of the Ohinemuri River and confluences with tributaries and approximately 20 hectares land in the Paeroa township. The incremental impact of a Rainy Day breach on the natural environment is assessed to be catastrophic. 12.2.7. Potential Social, Cultural, and Economic Impact Damage on the Karangahake Gorge Historical Walkway, including the historical railway trail and several bridges, is considered. Department of Conservation (DOC) estimates that the site attracts about 80,000 visitors annually (Ref. 29). The site is one of DOC’s 50 Historic Icons, where the stories of the site are told and protected. The incremental effects over a flood are likely to be mostly related to the effect of tailings deposition clean up on tourism. Impact on water quality and the environment has significance for Maori. Water is a taonga for Maori and contamination of water would significantly impact on its mana and spiritual qualities (Mauri and Wairua). A breach would have an incremental impact for Maori over a natural flood because it would temporarily impact water quality.
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