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

<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