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Table 1 Generic and Auckland specific clean-up response thresholds for tephra clean-up operations (adapted from Hayes et al. 2015). See text for details on Auckland thresholds

From: A model to assess tephra clean-up requirements in urban environments

Tephra thickness Generic clean-up response (Hayes et al. 2015) Tephra thickness used in model Auckland clean-up response
<0.5 mm Minor clean-up operations on roads using street sweepers. Clean-up of airports. Property owners self-manage clean-up. <1 mm No coordinated clean-up
0.5–10 mm Coordinated clean-up of roads and airports using street sweepers. Property owners self-managed clean-up. 1–10 mm Coordinated clean-up of roads and airport using street sweepers. Property owners self-manage clean-up (0.75–7.5 m3 per property)
10–50 mm Coordinated clean-up of all roads and properties. Heavy machinery such as diggers and loaders will be required. Volunteer workforces may need to be managed. Further clean-up of roads using street sweepers may be required after the bulk of the material is removed. >10–50 mm Coordinated clean-up of all roads, airports, and private properties using labour, heavy machinery, and dump trucks. Property owners dump tephra on roadside (7.5–40 m3 per property)
>50 mm Coordinated clean-up of all impervious surfaces and recreational areas such as parks using heavy machinery. High demand for heavy machinery. >50 mm–200 mm Coordinated clean-up of all areas using labour, heavy machinery, and dump trucks. Property owners dump tephra at roadside (>38 m3 per property)
>200 mm Coordinated clean-up of all areas using labour, heavy machinery, and dump trucks. Likelihood of considerable building damaged requires a carefully managed clean-up operation for health and safety